WO2024086978A1 - Positive electrode active material and preparation method therefor, positive electrode sheet, secondary battery and electric device - Google Patents

Positive electrode active material and preparation method therefor, positive electrode sheet, secondary battery and electric device Download PDF

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WO2024086978A1
WO2024086978A1 PCT/CN2022/127059 CN2022127059W WO2024086978A1 WO 2024086978 A1 WO2024086978 A1 WO 2024086978A1 CN 2022127059 W CN2022127059 W CN 2022127059W WO 2024086978 A1 WO2024086978 A1 WO 2024086978A1
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positive electrode
active material
electrode active
optionally
sintered product
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PCT/CN2022/127059
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French (fr)
Chinese (zh)
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桓书星
沈重亨
罗东升
王帮润
陈强
吴奇
柳娜
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/127059 priority Critical patent/WO2024086978A1/en
Publication of WO2024086978A1 publication Critical patent/WO2024086978A1/en

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  • the present application relates to the technical field of secondary batteries, and in particular to a positive electrode active material and a preparation method thereof, a positive electrode sheet including the positive electrode active material, a secondary battery and an electrical device.
  • Secondary batteries are widely used in various consumer electronic products and electric vehicles due to their outstanding features of light weight, no pollution and no memory effect.
  • positive electrode materials are an important component of lithium-ion batteries.
  • common positive electrode materials include layered structure materials (such as lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, etc.), spinel structure materials, polyanion materials and ternary materials. High nickel ternary materials have received more and more attention due to their high energy density, low cost and reliable safety.
  • the present application is made in view of the above-mentioned problems, and its purpose is to provide a positive electrode active material, aiming to make the secondary battery containing the positive electrode active material have improved electrode sheet compaction density, energy density and cycle performance.
  • the first aspect of the present application provides a positive electrode active material, wherein the specific surface area (BET) of the positive electrode active material is ⁇ m 2 /g, the particle size Dv50 is ⁇ m, the 4T powder compaction density (CPD(4T)) is ⁇ g/cm 3 , and they satisfy the following relationship:
  • a pole sheet compaction density of at least 3.7 g/cm 3 can be achieved, so that a secondary battery prepared from the positive electrode active material has a higher energy density and improved cycle performance.
  • the positive electrode material has the following general formula:
  • the positive electrode active material When the positive electrode active material satisfies the relationship defined in this application, it can broaden the lithium ion channel and stabilize the material structure, so that the positive electrode material has a higher discharge capacity and a greatly improved cycle life. It can also effectively prevent the dissolution of transition metals and improve storage and safety performance.
  • the positive electrode active material includes a first positive electrode active material and a second positive electrode active material, wherein the first positive electrode active material is a polycrystalline material having the following general formula:
  • M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce;
  • the second positive electrode active material is a single crystal-like material having the following general formula:
  • M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce.
  • the particle size Dv50 of the positive electrode active material is ⁇ ⁇ m, wherein ⁇ is 4.0 to 15, and optionally 4.5 to 10.
  • the Dv50 of the first positive electrode active material is 6 ⁇ m to 20 ⁇ m, and optionally 7 ⁇ m to 18 ⁇ m.
  • the Dv50 of the second positive electrode active material is 2 ⁇ m to 6 ⁇ m, and optionally 2.5 ⁇ m to 4.0 ⁇ m.
  • the cycle performance can be better ensured, and the structural and kinetic properties of the material can be ensured.
  • the specific surface area (BET) of the positive electrode active material is ⁇ m 2 /g, wherein ⁇ is 0.34 to 0.8, and optionally 0.45 to 0.7.
  • the specific surface area (BET) of the first cathode active material is 0.2 m 2 /g to 0.8 m 2 /g; and/or the specific surface area (BET) of the second cathode active material is 0.6 m 2 /g to 1.3 m 2 /g.
  • the corrosion of the positive electrode active materials by the electrolyte can be delayed, the kinetic performance thereof can be ensured, and the materials can be easily processed.
  • the 4T powder compaction density (CPD(4T)) of the positive electrode active material is ⁇ g/cm 3 , wherein ⁇ is 3.2 to 4.2, and optionally 3.3 to 4.0.
  • the 4T powder compaction density (CPD(4T)) of the first cathode active material is 3.1 g/cm 3 to 3.7 g/cm 3 ; and/or the 4T powder compaction density (CPD(4T)) of the second cathode active material is 3.1 g/cm 3 to 3.7 g/cm 3 .
  • the pole sheet compaction density required by the present application can be ensured.
  • the SPAN value of the positive electrode active material is 1.4 to 2.7, and optionally 1.5 to 2.5.
  • the SPAN value of the first cathode active material is 0.9 to 1.5; and/or the SPAN value of the second cathode active material is 1.0 to 1.7.
  • the positive electrode active material has high dispersibility, thereby preparing a high compaction density positive electrode sheet.
  • high dispersibility can ensure that the single crystal-like small particles have good gap filling ability, making the materials more closely combined, thereby preparing a high compaction density positive electrode sheet.
  • the mass ratio of the first positive electrode active material to the second positive electrode active material is (9-1):1, and can be optionally (6-1.5):1.
  • the compaction density of the electrode sheet can be improved, while at the same time being able to utilize the advantages of the high capacity of the first positive electrode active material and the high cycle life of the second positive electrode active material to achieve optimization of capacity and electrical performance.
  • the second aspect of the present application also provides a method for preparing the positive electrode active material described in the first aspect of the present application, which comprises the following steps:
  • the lithium source and the precursor of the positive electrode active material are mixed uniformly and sintered in an oxygen atmosphere to obtain a first sintered product; the sintered product is crushed, screened and graded to obtain the positive electrode active material; optionally, the first sintered product is crushed and then washed in an aqueous solution containing a lithium source or in deionized water.
  • the first sintered product is uniformly mixed with another compound containing an element M and sintered for a second time in an oxygen atmosphere to obtain a second sintered product; the second sintered product is crushed, screened and graded to obtain a positive electrode active material; wherein M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce;
  • the sintering temperature is 550-900° C.; and the sintering time is 5-20 h.
  • S1 uniformly mixing a lithium source, a precursor of a first positive electrode active material and a compound containing element M and performing a first sintering in an oxygen atmosphere to obtain a first sintered product; crushing the first sintered product, uniformly mixing it with another compound containing element M and performing a second sintering in an oxygen atmosphere to obtain a second sintered product; crushing, screening and grading the second sintered product to obtain a first positive electrode active material; optionally, the sintering temperature is 550° C. to 800° C.; the sintering time is 5 h to 20 h;
  • S2 uniformly mixing a lithium source, a precursor of a second positive electrode active material and a compound containing element M and performing a first sintering in an oxygen atmosphere to obtain a first sintered product; crushing the first sintered product, uniformly mixing it with another compound containing element M and performing a second sintering in an oxygen atmosphere to obtain a second sintered product; crushing, screening and grading the second sintered product to obtain a second positive electrode active material; optionally, the sintering temperature is 600° C. to 900° C.; the sintering time is 5 h to 20 h;
  • the lithium source is selected from at least one of lithium carbonate, lithium hydroxide and lithium oxalate.
  • the precursor of the first cathode active material and the precursor of the second cathode active material are each at least one of Ni1 -x- yCoxMny (OH) 2 and Ni1 -xyCoxMnyCO3 , wherein 0.01 ⁇ x ⁇ 0.1 , 0.01 ⁇ y ⁇ 0.1 .
  • the element M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce.
  • the concentration of oxygen in the oxygen atmosphere is 80% or more, optionally 90% or more, and further optionally 99.9% or more.
  • a positive electrode active material with a high electrode compaction density can be obtained.
  • doping and coating with transition metal elements not only the structural stability of the material can be improved, but also the capacity, cycle life and storage performance of the positive electrode active material can be improved.
  • the third aspect of the present application provides a positive electrode plate, which includes a positive electrode collector and a positive electrode film layer arranged on at least one surface of the positive electrode collector, the positive electrode film layer includes the positive electrode active material described in the first aspect of the present application or the positive electrode active material prepared by the method described in the second aspect of the present application, and the content of the positive electrode active material in the positive electrode film layer is more than 10% by weight, based on the total weight of the positive electrode film layer.
  • the fourth aspect of the present application provides a secondary battery, which includes the positive electrode active material of the first aspect of the present application or the positive electrode active material prepared by the method of the second aspect of the present application or the positive electrode plate of the third aspect of the present application.
  • a fifth aspect of the present application provides an electrical device, comprising the secondary battery of the fourth aspect of the present application.
  • the electric device of the present application includes the secondary battery provided by the present application, it has at least the same advantages as the secondary battery.
  • FIG. 1 is a scanning electron microscope image of a cross section of a positive electrode sheet prepared from the positive electrode active material of Example 1 of the present application.
  • FIG. 2 is a normal temperature cycle diagram of a secondary battery prepared from the positive electrode active materials of Example 1 (2a) and Comparative Example 1 (2b) and Comparative Example 2 (2c) of the present application.
  • FIG. 3 is a schematic diagram of a battery cell according to an embodiment of the present application.
  • FIG. 4 is an exploded view of the battery cell according to the embodiment of the present application shown in FIG. 3 .
  • FIG. 5 is a schematic diagram of a battery module according to an embodiment of the present application.
  • FIG. 6 is a schematic diagram of a battery pack according to an embodiment of the present application.
  • FIG. 7 is an exploded view of the battery pack shown in FIG. 6 according to an embodiment of the present application.
  • FIG. 8 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.
  • “Scope” disclosed in the present application is defined in the form of lower limit and upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range.
  • the scope defined in this way can be including end values or excluding end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just the abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may further include step (c), which means that step (c) may be added to the method in any order.
  • the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the “include” and “comprising” mentioned in this application represent open-ended or closed-ended expressions.
  • the “include” and “comprising” may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • the compaction density of the positive electrode plate is usually increased.
  • the greater the compaction density of the plate the greater the degree of compression between the material particles, which makes the plate's absorption performance of the electrolyte worse, and the electrolyte is difficult to infiltrate the active material, resulting in a decrease in the battery's cycle performance.
  • the compaction density of the positive electrode plate can usually reach up to 3.5g/ cm3 . Generally, it becomes very difficult to further increase the compaction density of the plate and maintain the battery's cycle performance.
  • the compaction density of the pole piece is positively correlated with the compaction density of the powder to a large extent, and many research patents have also confirmed this point (see, for example, CN113921782A), but the factor affecting the compaction density of the pole piece is not only the compaction density of the powder.
  • the median particle size Dv50 of the positive electrode material can also affect the compaction density of the pole piece and its cycle life.
  • the particle size distribution of the positive electrode material will shift to the left as a whole, and there will be more small particles, and the material filling capacity will become stronger, but Dv50 cannot be too small, otherwise it will cause too much micropowder to affect the processing performance. Therefore, there are many factors that affect the compaction density of the pole piece.
  • the inventors unexpectedly discovered that when the compaction density, median particle size and specific surface area of the positive electrode active material meet the conditions specified in the present application, a pole piece compaction density of at least 3.7 g/ cm3 can be achieved, and the electrical performance of the prepared battery can also be improved.
  • the first aspect of the present application provides a positive electrode active material, wherein the specific surface area (BET) of the positive electrode active material is ⁇ m 2 /g, the particle size Dv50 is ⁇ m, and the 4T powder compaction density (CPD(4T)) is ⁇ g/cm 3 , and they satisfy the following relationship:
  • a pole sheet compaction density of at least 3.7 g/cm 3 can be achieved, and a secondary battery prepared from the positive electrode active material has a higher energy density and improved cycle performance.
  • the cathode material has the following general formula:
  • the positive electrode active material When the positive electrode active material satisfies the relationship defined in this application, it can broaden the lithium ion channel and stabilize the material structure, so that the positive electrode material has a higher discharge capacity and a greatly improved cycle life. At the same time, it can also effectively prevent the dissolution of transition metals and improve storage and safety performance.
  • the positive electrode active material includes a first positive electrode active material and a second positive electrode active material, wherein the first positive electrode active material is a polycrystalline material having the following general formula:
  • M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce;
  • the second positive electrode active material is a single crystal-like material having the following general formula:
  • M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce.
  • the polycrystal refers to a secondary particle, which is a state in which a plurality of primary particles are aggregated together to form a spherical particle;
  • the quasi-single crystal refers to a primary particle, which is larger than 0.9 ⁇ m in size, and is a single particle or a state in which several primary particles are adhered but without obvious agglomeration.
  • the above-mentioned limitation on the numerical range of z1 is not only a limitation on the stoichiometric number of each element as M, but also a limitation on the sum of the stoichiometric numbers of each element as M. That is, when M is more than two elements M1, M2...Mn, the stoichiometric numbers z11, z12...z1n of M1, M2...Mn must each fall within the numerical range of z1 defined in the present application, and the sum of z11, z12...z1n must also fall within the numerical range.
  • first positive electrode active material polycrystalline material and polycrystalline agglomerates
  • second positive electrode active material single crystal material and single crystal-like small particles
  • the particle size Dv50 of the positive electrode active material is ⁇ ⁇ m, wherein ⁇ is 4.0 to 15, optionally 4.5 to 10, and further optionally 4.7 to 9.
  • the Dv50 of the first positive electrode active material is 6 ⁇ m to 20 ⁇ m, optionally 7 ⁇ m to 18 ⁇ m, and further optionally 8.5 ⁇ m to 17.8 ⁇ m.
  • the Dv50 of the second positive active material is 2 ⁇ m to 6 ⁇ m, optionally 2.5 ⁇ m to 4.0 ⁇ m, and further optionally 2.6 ⁇ m to 3.9 ⁇ m.
  • the cycle performance can be better ensured, and the structural and kinetic properties of the material can be ensured.
  • the specific surface area (BET) of the positive electrode active material is ⁇ m 2 /g, wherein ⁇ is 0.34 to 0.8, optionally 0.45 to 0.7, and further optionally 0.46 to 0.68.
  • the specific surface area (BET) of the first cathode active material is 0.2m2 /g to 0.8m2 /g, optionally 0.25m2 /g to 0.6m2 /g; and/or the specific surface area (BET) of the second cathode active material is 0.6m2 /g to 1.3m2 /g, optionally 0.7m2 /g to 1.2m2 /g.
  • the corrosion of the positive electrode active materials by the electrolyte can be delayed, the kinetic performance thereof can be ensured, and the materials can be easily processed.
  • the specific surface area test refers to GB/T 19587-2017, and the nitrogen adsorption specific surface area analysis test method is used for testing using the Tri-Star 3020 specific surface area pore size analyzer of Micromeritics, USA.
  • the specific surface area of the material is calculated using the BET (Brunauer Emmett Teller) method.
  • the 4T powder compaction density (CPD(4T)) of the positive electrode active material is ⁇ g/cm 3 , wherein ⁇ is 3.2 to 4.2, and optionally 3.3 to 4.0.
  • the 4T powder compaction density (CPD(4T)) of the first cathode active material is 3.1 g/cm 3 to 3.7 g/cm 3 , optionally 3.2 g/cm 3 to 3.6 g/cm 3 ; and/or the 4T powder compaction density (CPD(4T)) of the second cathode active material is 3.1 g/cm 3 to 3.7 g/cm 3 , optionally 3.2 g/cm 3 to 3.5 g/cm 3 .
  • the pole piece compaction density required by the present application can be ensured.
  • the powder compaction density can reflect the pole piece compaction density to a certain extent. When BET, particle size, etc. remain unchanged, the higher the powder compaction density, the greater the pole piece compaction density.
  • the powder compaction density can be measured according to GB/T 24533-2009.
  • the SPAN value of the positive electrode active material is 1.4 to 2.7, optionally 1.5 to 2.5, further optionally 1.8 to 2.4, further optionally 1.9 to 2.25, further optionally 2.05 to 2.24.
  • the SPAN value (Dv90-Dv10)/Dv50.
  • the SPAN value of the first cathode active material is 0.9 to 1.5, optionally 1.0 to 1.4, and optionally 1.2 to 1.4; and/or the SPAN value of the second cathode active material is 1.0 to 1.7, and optionally 1.3 to 1.65.
  • the positive electrode active material has high dispersibility, thereby preparing a high compaction density positive electrode sheet.
  • high dispersibility can ensure that the single crystal-like small particles have good gap filling ability, making the materials more closely combined, thereby preparing a high compaction density positive electrode sheet.
  • the mass ratio of the first positive electrode active material to the second positive electrode active material is (9-1):1, optionally (6-1.5):1, further optionally (5.8-2):1, further optionally (5.5-2.2):1, and further optionally (4-2.5):1.
  • the mass ratio of the first positive electrode active material to the second positive electrode active material is (90-40):(60-10), optionally (85-50):(50-25), and further optionally (80-60):(40-20), and the sum of the masses of the first positive electrode active material and the second positive electrode active material is calculated as 100 parts.
  • the compaction density of the electrode sheet can be improved, while taking advantage of the high capacity of the first positive electrode active material and the high cycle life of the second positive electrode active material to achieve optimization of capacity and electrical performance.
  • the second aspect of the present application also provides a method for preparing the positive electrode active material described in the first aspect of the present application, which comprises the following steps:
  • the lithium source and the precursor of the positive electrode active material are mixed uniformly and sintered in an oxygen atmosphere to obtain a first sintered product; the sintered product is crushed, screened and graded to obtain the positive electrode active material; optionally, the first sintered product is crushed and then washed in an aqueous solution containing a lithium source or in deionized water.
  • the first sintered product is uniformly mixed with another compound containing an element M and sintered for a second time in an oxygen atmosphere to obtain a second sintered product; the second sintered product is crushed, screened and graded to obtain a positive electrode active material; wherein M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce;
  • the sintering temperature is 550-900° C.; and the sintering time is 5-20 h.
  • it comprises the following steps:
  • S1 uniformly mixing a lithium source, a precursor of a first positive electrode active material and a compound containing element M and performing a first sintering in an oxygen atmosphere to obtain a first sintered product; crushing the first sintered product, uniformly mixing it with another compound containing element M and performing a second sintering in an oxygen atmosphere to obtain a second sintered product; crushing, screening and grading the second sintered product to obtain a first positive electrode active material; optionally, the sintering temperature is 550° C. to 800° C.; the sintering time is 5 h to 20 h;
  • S2 uniformly mixing a lithium source, a precursor of a second positive electrode active material and a compound containing element M and performing a first sintering in an oxygen atmosphere to obtain a first sintered product; crushing the first sintered product, uniformly mixing it with another compound containing element M and performing a second sintering in an oxygen atmosphere to obtain a second sintered product; crushing, screening and grading the second sintered product to obtain a second positive electrode active material; optionally, the sintering temperature is 600°C to 900°C; the sintering time is 5h to 20h;
  • the lithium source is selected from at least one of lithium carbonate, lithium hydroxide and lithium oxalate.
  • the precursor of the first cathode active material and the precursor of the second cathode active material are each at least one of Ni1 -x- yCoxMny (OH) 2 and Ni1 -xyCoxMnyCO3 , wherein 0.01 ⁇ x ⁇ 0.1 , 0.01 ⁇ y ⁇ 0.1 .
  • the precursor of the first positive electrode active material and the precursor of the second positive electrode active material can be prepared by a method known in the prior art (e.g., by coprecipitation reaction). For example, by preparing an aqueous solution of nickel sulfate, cobalt sulfate and manganese sulfate, and then placing the solution in a reactor and adjusting the particle size and microscopic morphology by controlling the reaction time, reaction temperature, pH value and ammonia concentration, the first and second positive electrode active material precursors with different particle sizes can be prepared respectively.
  • the molar ratio of the lithium source to the precursor of the first positive electrode active material is (0.97-1.09):1, and can be optionally (1-1.05):1.
  • the added amount of the compound containing element M is generally 100 ppm to 9000 ppm, optionally 200 ppm to 7000 ppm, further optionally 500 ppm to 5000 ppm, and further optionally 800 ppm to 2000 ppm, based on the total mass of the lithium source and the precursor of the first positive electrode active material.
  • the addition amount of another compound containing element M is generally 100 ppm to 9000 ppm, optionally 200 ppm to 7000 ppm, further optionally 500 ppm to 5000 ppm, further optionally 800 ppm to 2000 ppm, based on the total mass of the lithium source and the precursor of the first positive electrode active material.
  • the sintering temperature of the first sintering is 550°C to 800°C, optionally 650°C to 750°C, and the sintering time is 5h to 20h, optionally 10h to 18h.
  • the sintering temperature of the second sintering is 400°C to 720°C, optionally 420°C to 500°C, and the sintering time is 5h to 20h, optionally 8h to 15h.
  • the element M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce.
  • the compound containing the element M is selected from one or more of a simple substance, an oxide, a boride, a phosphate, an oxalate, a carbonate and a sulfate of M.
  • steps S1 and S2 two compounds containing element M are used in each step, that is, the first compound containing element M is different from the other compound containing element M.
  • the concentration of oxygen in the oxygen atmosphere is greater than 80%, optionally greater than 90%, and further optionally greater than 99.9%.
  • step S2 the molar ratio of the lithium source to the precursor of the second positive electrode active material is (0.97-1.09):1, and can be optionally (1-1.05):1.
  • the added amount of the compound containing element M is generally 100 ppm to 9000 ppm, optionally 200 ppm to 7000 ppm, further optionally 300 ppm to 4000 ppm, and further optionally 400 ppm to 1000 ppm, based on the total mass of the lithium source and the precursor of the first positive electrode active material.
  • the addition amount of another compound containing element M is generally 100 ppm to 9000 ppm, optionally 200 ppm to 7000 ppm, further optionally 500 ppm to 5000 ppm, and further optionally 800 ppm to 2000 ppm, based on the total mass of the lithium source and the precursor of the first positive electrode active material.
  • the sintering temperature of the first sintering is 600°C to 900°C, and may be 700°C to 850°C, and the sintering time is 5h to 20h, and may be 10h to 18h.
  • the concentration of the lithium source in the lithium source aqueous solution is 2 g/L to 5 g/L, and can also be 3 g/L to 4 g/L; and/or, the lithium source is selected from at least one of lithium carbonate, lithium hydroxide and lithium oxalate.
  • the first sintered product is preferably crushed and washed in an aqueous solution containing a lithium source.
  • an aqueous solution containing a lithium source By using an aqueous solution containing a lithium source, the cycle performance of the prepared secondary battery can be better ensured, and the structural and dynamic properties of the material can be ensured.
  • the drying temperature is 80°C to 180°C, and may be 100°C to 150°C, and the drying time is 1 hour to 8 hours, and may be 3 hours to 4 hours.
  • the sintering temperature of the second sintering is 400°C to 820°C, optionally 420°C to 600°C, and the sintering time is 5h to 20h, and optionally 8h to 15h.
  • the mass ratio of the first positive electrode active material to the second positive electrode active material is (9-1):1, optionally (6-1.5):1, further optionally (5.8-2):1, further optionally (5.5-2.2):1, and further optionally (4-2.5):1.
  • the mixing time can be adjusted as needed, and can be selected to be 0.5 h to 2 h.
  • the third aspect of the present application provides a positive electrode plate, which includes a positive electrode collector and a positive electrode film layer arranged on at least one surface of the positive electrode collector, the positive electrode film layer includes the positive electrode active material described in the first aspect of the present application or the positive electrode active material prepared by the method described in the second aspect of the present application, and the content of the positive electrode active material in the positive electrode film layer is more than 10 weight%, based on the total weight of the positive electrode film layer.
  • the content of the positive electrode active material in the positive electrode film layer is 95-99.5% by weight, and optionally 96-99% by weight, based on the total weight of the positive electrode film layer.
  • the surface density of the positive electrode sheet is 17.5 mg/cm 2 to 22 mg/cm 2 , and can be 18.5 mg/cm 2 to 21 mg/cm 2 .
  • the surface density of the positive electrode film layer has a meaning well known in the art and can be tested by methods known in the art. For example, take a single-sided coated and cold-pressed positive electrode sheet (if it is a double-sided coated positive electrode sheet, the positive electrode active material layer on one side can be wiped off first), punch it into small discs with an area of S1, weigh it, and record it as M1. Then wipe off the positive electrode active material layer of the above-mentioned weighed positive electrode sheet, weigh the weight of the positive electrode collector, and record it as M0.
  • the surface density of the positive electrode active material layer (weight of the positive electrode sheet M1 - weight of the positive electrode collector M0) / S1.
  • multiple groups for example, 10 groups
  • the average value is calculated as the test result.
  • the compaction density of the positive electrode sheet is 3.7 g/cm 3 to 4 g/cm 3 , and can be 3.7 g/cm 3 to 3.85 g/cm 3 .
  • the elongation of the positive electrode sheet is 0.7% to 0.8%.
  • the fourth aspect of the present application provides a secondary battery, which includes the positive electrode active material of the first aspect of the present application or the positive electrode active material prepared by the method of the second aspect of the present application or the positive electrode plate of the third aspect of the present application.
  • a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator.
  • active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet.
  • the electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet.
  • the separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
  • the secondary battery of the present application is described below with reference to the accompanying drawings as appropriate.
  • the secondary battery may be in the form of a battery cell, a battery module, or a battery pack.
  • a battery cell is provided.
  • a battery cell includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator.
  • active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet.
  • the electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet.
  • the separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
  • the positive electrode plate includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes the positive electrode active material of the first aspect of the present application.
  • the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used as the metal foil.
  • the composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the positive electrode active material may also be a positive electrode active material for a battery known in the art.
  • the positive electrode active material may include at least one of the following materials: a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to , lithium cobalt oxide (such as LiCoO2 ), lithium nickel oxide (such as LiNiO2 ), lithium manganese oxide (such as LiMnO2 , LiMn2O4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi1 / 3Co1 / 3Mn1 / 3O2 (also referred to as NCM333 ), LiNi0.5Co0.2Mn0.3O2 (also referred to as NCM523 ) , LiNi0.5Co0.25Mn0.25O2 (also referred to as NCM211 ) , LiNi0.6Co0.2Mn0.2O2 (also referred to as NCM622 ), LiNi0.8Co0.1Mn0.1O2 (also referred to as NCM811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.
  • lithium iron phosphate such as LiFePO 4 (also referred to as LFP)
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate
  • LiMnPO 4 lithium manganese phosphate and carbon
  • the positive electrode film layer may further optionally include a binder.
  • the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • vinylidene fluoride-tetrafluoroethylene-propylene terpolymer vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer
  • the binder accounts for 0.1% to 4% by mass of the positive electrode film layer, and optionally 0.5% to 2% by mass.
  • the positive electrode film layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • a conductive agent which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the conductive agent accounts for 0.1% to 4% by mass of the positive electrode film layer, and can be optionally 0.5% to 2% by mass.
  • the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
  • a solvent such as N-methylpyrrolidone
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.
  • the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • the metal foil copper foil may be used.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the negative electrode active material may be a negative electrode active material for a battery known in the art.
  • the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys.
  • the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.
  • the mass percentage of the negative electrode active material in the negative electrode film layer is 75% to 99%, and optionally 80% to 98%.
  • the negative electrode film layer may further include a binder.
  • the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the binder accounts for 0.1% to 3.5% by mass of the negative electrode film layer, and optionally 0.5% to 2.5% by mass.
  • the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • a conductive agent which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
  • the conductive agent accounts for 0.04% to 5% by mass of the negative electrode film layer, and can be optionally 0.5% to 3% by mass.
  • the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).
  • a thickener eg, sodium carboxymethyl cellulose (CMC-Na)
  • the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
  • a solvent such as deionized water
  • the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
  • the present application has no specific restrictions on the type of electrolyte, which can be selected according to needs.
  • the electrolyte can be liquid, gel or all-solid.
  • the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.
  • the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.
  • the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
  • the concentration of the electrolyte salt in the non-aqueous electrolyte is, for example, 0.3 mol/L (mole/liter) or more, optionally 0.7 mol/L or more, optionally 1.7 mol/L or less, and further optionally 1.2 mol/L or less.
  • the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • additives such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • the battery cell further includes a separator.
  • the present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer can be the same or different, without particular limitation.
  • the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.
  • the battery cell may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.
  • the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • FIG3 is a battery cell 5 of a square structure as an example.
  • the outer package may include a shell 51 and a cover plate 53.
  • the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is encapsulated in the receiving cavity.
  • the electrolyte is infiltrated in the electrode assembly 52.
  • the number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • battery cells may be assembled into a battery module.
  • the number of battery cells contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.
  • FIG5 is a battery module 4 as an example.
  • a plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.
  • the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.
  • the battery cells can be assembled into a battery pack.
  • the battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.
  • FIG6 and FIG7 are battery packs 1 as an example.
  • the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box.
  • the battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 to form a closed space for accommodating the battery modules 4.
  • the plurality of battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electric device, the electric device includes the secondary battery provided in the present application.
  • the secondary battery can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device.
  • the electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.
  • a secondary battery can be selected according to its usage requirements.
  • FIG8 is an example of an electric device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.
  • a battery pack or a battery module may be used.
  • a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be light and thin, and a battery cell may be used as a power source.
  • the polycrystalline agglomerates P and the single-crystal-like small particles S are uniformly mixed in a mass ratio of 75:25 to obtain the positive electrode active material of the present application.
  • the positive electrode active material, conductive agent acetylene black (SP) and binder polyvinylidene fluoride (PVDF) were put into a 5L stirring tank at a mass ratio of 97:1.5:1.5 for premixing for 30 minutes, and finally N-methylpyrrolidone (NMP) was added as solvent and stirred rapidly under vacuum to form slurry with a solid content of 70% by weight.
  • NMP N-methylpyrrolidone
  • the slurry was evenly coated on both sides of an aluminum foil with a thickness of 12 ⁇ m.
  • the coated electrode was taken out after drying in an oven at 100°C for half an hour, with a surface density of 19.5mg/ cm2 and a compacted density of 3.70g/ cm3 .
  • the negative electrode active material artificial graphite, hard carbon, conductive agent acetylene black, binder styrene butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) were mixed uniformly in deionized water at a weight ratio of 90:5:2:2:1, coated on copper foil, dried, and cold pressed to obtain a negative electrode sheet with a coating amount of 12.5 g/ cm2 .
  • Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1, and then LiPF6 is uniformly dissolved in the above solution to obtain an electrolyte, wherein the concentration of LiPF6 is 1 mol/L.
  • a polyethylene (PE) porous polymer film is used as the isolation membrane.
  • the positive electrode sheet, separator, and negative electrode sheet are stacked in order, so that the separator is between the positive and negative electrodes to play a role of isolation, and then wound to obtain a bare cell.
  • the bare cell is placed in an outer package, injected with electrolyte and packaged to obtain a full battery.
  • the length ⁇ width ⁇ height of the full battery 90mm ⁇ 30mm ⁇ 60mm, and the battery group margin is 97%.
  • the preparation method is basically the same as that of Example 1, but only some parameters are changed. For specific variables, see Tables 1 and 2.
  • the preparation method is similar to that of Example 1, except that only the first positive electrode active material is used and the parameters of the first positive electrode active material are different, see Table 2 for details.
  • the preparation method is similar to that of Example 1, except that the mixing ratio of the first positive electrode active material and the second positive electrode active material and their parameters are different, see Tables 1 and 2 for details.
  • the preparation method is similar to that of Example 1, except that only the first positive electrode active material is used and the parameters of the first positive electrode active material are different, see Table 2 for details.
  • the length after roller cold pressing is L1.
  • the specific surface area test was carried out according to GB/T 19587-2017, using the Tri-Star 3020 specific surface area pore size analyzer from Micromeritics, USA, to perform nitrogen adsorption specific surface area analysis test method, and the specific surface area of the material was calculated using the BET (Brunauer Emmett Teller) method.
  • BET Brunauer Emmett Teller
  • the particle size of the positive electrode active material is determined according to GB/T 19077.1-2016/ISO 13320:2009 (laser diffraction method for particle size distribution). Take a clean beaker, add an appropriate amount of the above-mentioned positive electrode active material, add an appropriate amount of pure water, and use ultrasound at 120W/5min to ensure that the material powder is completely dispersed in the water. After the solution is poured into the injection tower of the laser particle size analyzer (Malvern Company, model: Mastersizer3000), it circulates to the test optical path system with the solution.
  • the laser particle size analyzer Malvern Company, model: Mastersizer3000
  • the particles are irradiated by the laser beam, and the particle size distribution characteristics of the particles (shading degree: 8-12%) can be obtained by receiving and measuring the energy distribution of the scattered light, and the corresponding values of Dv10, Dv50, and Dv90 are read.
  • the test results are shown in Tables 1 and 2.
  • the compaction density of the positive electrode active material under 4T pressure (i.e., under 4 tons of pressure) is determined according to GB/T 24533-2009.
  • a certain amount of the powder of the positive electrode active material is placed in a special compaction mold, and then the mold is placed on the compaction density instrument.
  • the test results are shown in Tables 1 and 2.
  • the morphology of the cross section of the positive electrode sheet made of the positive electrode active material of Example 1 was characterized using a field emission scanning electron microscope (Sigma300) from ZEISS, Germany. The result is shown in FIG1 .
  • the secondary battery prepared by using the positive electrode active material of the present application not only has a better electrode compaction density and achieves a higher energy density, but also can achieve better cycle performance.

Abstract

The present application relates to a positive electrode active material. The specific surface area (BET) of the positive electrode active material is α m2/g, the particle size Dv50 is β μm, the 4T powder compaction density (CPD(4T)) is ɣ g/cm3, and these meet the following relational expression: -α2+1.24α+0.136ɣ-0.0123β=K, and 0.75≤K≤0.85. Under the condition that the positive electrode active material meets the relational expression defined in the present application, the compaction density of an electrode sheet of at least 3.7 g/cm3 can be realized, and moreover, the secondary battery prepared from the positive electrode active material has higher energy density and improved cycle performance. The present application further provides a secondary battery comprising the positive electrode active material and an electric device.

Description

正极活性材料及其制备方法、正极极片、二次电池和用电装置Positive electrode active material and preparation method thereof, positive electrode sheet, secondary battery and electric device 技术领域Technical Field
本申请涉及二次电池技术领域，尤其涉及一种正极活性材料及其制备方法、包括该正极活性材料的正极极片、二次电池和用电装置。The present application relates to the technical field of secondary batteries, and in particular to a positive electrode active material and a preparation method thereof, a positive electrode sheet including the positive electrode active material, a secondary battery and an electrical device.
背景技术Background technique
二次电池因具有重量轻、无污染、无记忆效应突出特点，被广泛应用于各类消费类电子产品和电动车辆中。在二次电池结构中，正极材料是锂离子电池的重要组成部分，目前常见的正极材料有层状结构材料(例如钴酸锂、锰酸锂、镍酸锂等)、尖晶石结构材料、聚阴离子型材料以及三元材料等。高镍三元材料因其具有较高的能量密度，较低廉的成本以及较可靠的安全性，受到了越来越多的关注。Secondary batteries are widely used in various consumer electronic products and electric vehicles due to their outstanding features of light weight, no pollution and no memory effect. In the structure of secondary batteries, positive electrode materials are an important component of lithium-ion batteries. Currently, common positive electrode materials include layered structure materials (such as lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, etc.), spinel structure materials, polyanion materials and ternary materials. High nickel ternary materials have received more and more attention due to their high energy density, low cost and reliable safety.
然而，使用现有技术正极活性材料的二次电池的能量密度和循环寿命仍有待进一步改善。However, the energy density and cycle life of secondary batteries using prior art cathode active materials still need to be further improved.
发明内容Summary of the invention
本申请是鉴于上述课题而进行的，其目的在于，提供一种正极活性材料，旨在使含有其的二次电池具有改善的极片压实密度、能量密度和循环性能。The present application is made in view of the above-mentioned problems, and its purpose is to provide a positive electrode active material, aiming to make the secondary battery containing the positive electrode active material have improved electrode sheet compaction density, energy density and cycle performance.
为达到上述目的，本申请的第一方面提供了一种正极活性材料，所述正极活性材料的比表面积(BET)为αm 2/g、粒径Dv50为βμm、4T粉末压实密度(CPD(4T))为γg/cm 3，并且它们满足以下关系式： To achieve the above object, the first aspect of the present application provides a positive electrode active material, wherein the specific surface area (BET) of the positive electrode active material is αm 2 /g, the particle size Dv50 is βμm, the 4T powder compaction density (CPD(4T)) is γg/cm 3 , and they satisfy the following relationship:
-α 2+1.24α+0.136γ-0.0123β＝K，且0.75≤K≤0.85。 -α 2 +1.24α+0.136γ-0.0123β=K, and 0.75≤K≤0.85.
正极活性材料在满足本申请限定的关系式的情况下，可以实现至少3.7g/cm 3的极片压实密度，使得由该正极活性材料制备的二次电池具有更高的能量密度并同时还能改善循环性能。 When the positive electrode active material satisfies the relationship defined in the present application, a pole sheet compaction density of at least 3.7 g/cm 3 can be achieved, so that a secondary battery prepared from the positive electrode active material has a higher energy density and improved cycle performance.
在任意实施方式中，所述正极材料具有以下通式：In any embodiment, the positive electrode material has the following general formula:
LiNi 1-x-y-zCo xMn yM zO 2， LiNi1 - xyzCoxMnyMzO2 , ​
其中，0.01≤x≤0.1，0.01≤y≤0.1，0≤z≤0.2，可选地，0≤z≤0.1；Wherein, 0.01≤x≤0.1, 0.01≤y≤0.1, 0≤z≤0.2, optionally, 0≤z≤0.1;
正极活性材料在满足本申请限定的关系式的情况下，能够拓宽锂离子通道同时稳定材料结构，使正极材料具有更高的放电容量，循环寿命也大大提升，同时也可以有效预防过渡金属溶出，改善存储及安全性能。When the positive electrode active material satisfies the relationship defined in this application, it can broaden the lithium ion channel and stabilize the material structure, so that the positive electrode material has a higher discharge capacity and a greatly improved cycle life. It can also effectively prevent the dissolution of transition metals and improve storage and safety performance.
在任意实施方式中，所述正极活性材料包括第一正极活性材料和第二正极活性材料，所述第一正极活性材料为多晶材料，其具有以下通式：In any embodiment, the positive electrode active material includes a first positive electrode active material and a second positive electrode active material, wherein the first positive electrode active material is a polycrystalline material having the following general formula:
LiNi 1-x1-y1-z1Co x1Mn y1M z1O 2， LiNi 1-x1-y1-z1 Co x1 Mn y1 M z1 O 2 ，
其中，0.01≤x 1≤0.1，0.01≤y 1≤0.1，0≤z 1≤0.2， Among them, 0.01≤x 1 ≤0.1, 0.01≤y 1 ≤0.1, 0≤z 1 ≤0.2,
M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种；M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce;
所述第二正极活性材料为类单晶材料，其具有以下通式：The second positive electrode active material is a single crystal-like material having the following general formula:
LiNi 1-x2-y2-z2Co x2Mn y2M z2O 2， LiNi 1-x2-y2-z2 Co x2 Mn y2 M z2 O 2 ,
其中，0.01≤x 2≤0.1，0.01≤y 2≤0.1，0≤z 2≤0.2， Among them, 0.01≤x 2 ≤0.1, 0.01≤y 2 ≤0.1, 0≤z 2 ≤0.2,
M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种。M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce.
在任意实施方式中，所述正极活性材料的粒径Dv50为βμm，其中β为4.0至15，可选为4.5至10。In any embodiment, the particle size Dv50 of the positive electrode active material is β μm, wherein β is 4.0 to 15, and optionally 4.5 to 10.
通过将正极活性材料的粒径控制在上述范围内，可以确保该材料拥有高容量的同时最大程度提升循环寿命。By controlling the particle size of the positive electrode active material within the above range, it is possible to ensure that the material has a high capacity while maximizing the cycle life.
在任意实施方式中，所述第一正极活性材料的Dv50为6μm至20μm，可选为7μm至18μm。In any embodiment, the Dv50 of the first positive electrode active material is 6 μm to 20 μm, and optionally 7 μm to 18 μm.
通过将第一正极活性材料的粒径控制在上述范围内，可以提供更高的容量，更好地保持循环容量。By controlling the particle size of the first positive electrode active material within the above range, a higher capacity can be provided and the cycle capacity can be better maintained.
在任意实施方式中，所述第二正极活性材料的Dv50为2μm至6 μm，可选为2.5μm至4.0μm。In any embodiment, the Dv50 of the second positive electrode active material is 2 μm to 6 μm, and optionally 2.5 μm to 4.0 μm.
通过将第二正极活性材料的粒径控制在上述范围内，可以更好地确保循环性能，确保材料的结构和动力学性能。By controlling the particle size of the second positive electrode active material within the above range, the cycle performance can be better ensured, and the structural and kinetic properties of the material can be ensured.
在任意实施方式中，所述正极活性材料的比表面积(BET)为αm 2/g，其中α为0.34至0.8，可选为0.45至0.7。 In any embodiment, the specific surface area (BET) of the positive electrode active material is αm 2 /g, wherein α is 0.34 to 0.8, and optionally 0.45 to 0.7.
在任意实施方式中，所述第一正极活性材料的比表面积(BET)为0.2m 2/g至0.8m 2/g；和/或，所述第二正极活性材料的比表面积(BET)为0.6m 2/g至1.3m 2/g。 In any embodiment, the specific surface area (BET) of the first cathode active material is 0.2 m 2 /g to 0.8 m 2 /g; and/or the specific surface area (BET) of the second cathode active material is 0.6 m 2 /g to 1.3 m 2 /g.
通过将本申请的第一和第二正极活性材料的比表面积设定在上述范围内，可以延缓电解液对正极活性材料的腐蚀，确保其动力学性能并使其易于加工。By setting the specific surface areas of the first and second positive electrode active materials of the present application within the above range, the corrosion of the positive electrode active materials by the electrolyte can be delayed, the kinetic performance thereof can be ensured, and the materials can be easily processed.
在任意实施方式中，所述正极活性材料的4T粉末压实密度(CPD(4T))为γg/cm 3，其中γ为3.2至4.2，可选3.3至4.0。 In any embodiment, the 4T powder compaction density (CPD(4T)) of the positive electrode active material is γ g/cm 3 , wherein γ is 3.2 to 4.2, and optionally 3.3 to 4.0.
在任意实施方式中，所述第一正极活性材料的4T粉末压实密度(CPD(4T))为3.1g/cm 3至3.7g/cm 3；和/或，所述第二正极活性材料的4T粉末压实密度(CPD(4T))为3.1g/cm 3至3.7g/cm 3。 In any embodiment, the 4T powder compaction density (CPD(4T)) of the first cathode active material is 3.1 g/cm 3 to 3.7 g/cm 3 ; and/or the 4T powder compaction density (CPD(4T)) of the second cathode active material is 3.1 g/cm 3 to 3.7 g/cm 3 .
通过将正极活性材料、第一和第二正极活性材料的4T粉末压实密度控制在上述范围内，可以确保实现本申请所需的极片压实密度。By controlling the 4T powder compaction density of the positive electrode active material and the first and second positive electrode active materials within the above range, the pole sheet compaction density required by the present application can be ensured.
在任意实施方式中，所述正极活性材料的SPAN值为1.4至2.7，可选1.5至2.5。In any embodiment, the SPAN value of the positive electrode active material is 1.4 to 2.7, and optionally 1.5 to 2.5.
在任意实施方式中，所述第一正极活性材料的SPAN值为0.9至1.5；和/或，所述第二正极活性材料的SPAN值为1.0至1.7。In any embodiment, the SPAN value of the first cathode active material is 0.9 to 1.5; and/or the SPAN value of the second cathode active material is 1.0 to 1.7.
通过将正极活性材料以及第一和第二正极活性材料的SPAN值控制在上述范围内，使其具有高分散性，从而制备得到高压实密度正极片。特别是高分散性可以确保类单晶小颗粒有较好的填缝能力，使材料结合更加紧密，从而制备得到高压实密度正极片。By controlling the SPAN values of the positive electrode active material and the first and second positive electrode active materials within the above range, the positive electrode active material has high dispersibility, thereby preparing a high compaction density positive electrode sheet. In particular, high dispersibility can ensure that the single crystal-like small particles have good gap filling ability, making the materials more closely combined, thereby preparing a high compaction density positive electrode sheet.
在任意实施方式中，所述第一正极活性材料与第二正极活性材料的质量比为(9-1):1，可选为(6-1.5):1。In any embodiment, the mass ratio of the first positive electrode active material to the second positive electrode active material is (9-1):1, and can be optionally (6-1.5):1.
将第一和第二正极活性材料的质量比控制在上述范围内，可以提 升极片的压实密度，同时能够利用第一正极活性材料的高容量、第二正极活性材料的高循环寿命的优点，实现容量和电性能最优化。By controlling the mass ratio of the first and second positive electrode active materials within the above range, the compaction density of the electrode sheet can be improved, while at the same time being able to utilize the advantages of the high capacity of the first positive electrode active material and the high cycle life of the second positive electrode active material to achieve optimization of capacity and electrical performance.
本申请的第二方面还提供一种制备本申请第一方面所述的正极活性材料的方法，其包括以下步骤：The second aspect of the present application also provides a method for preparing the positive electrode active material described in the first aspect of the present application, which comprises the following steps:
将锂源、正极活性材料的前驱体混合均匀并在氧气气氛中进行烧结，得到第一烧结产物；将烧结产物进行破碎、筛分和分级，得到正极活性材料；可选地，将第一烧结产物破碎后在含有锂源的水溶液中或去离子水中进行清洗。The lithium source and the precursor of the positive electrode active material are mixed uniformly and sintered in an oxygen atmosphere to obtain a first sintered product; the sintered product is crushed, screened and graded to obtain the positive electrode active material; optionally, the first sintered product is crushed and then washed in an aqueous solution containing a lithium source or in deionized water.
可选地，将第一烧结产物与另一包含元素M的化合物混合均匀并在氧气气氛中进行第二次烧结，得到第二烧结产物；将第二烧结产物进行破碎、筛分和分级，得到正极活性材料；所述M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种；Optionally, the first sintered product is uniformly mixed with another compound containing an element M and sintered for a second time in an oxygen atmosphere to obtain a second sintered product; the second sintered product is crushed, screened and graded to obtain a positive electrode active material; wherein M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce;
可选地，所述烧结温度为550-900℃；所述烧结时间为5-20h。Optionally, the sintering temperature is 550-900° C.; and the sintering time is 5-20 h.
在任意实施方式中，其包括以下步骤：In any embodiment, it comprises the following steps:
S1：将锂源、第一正极活性材料的前驱体和包含元素M的化合物混合均匀并在氧气气氛中进行第一次烧结，得到第一烧结产物；将第一烧结产物破碎，与另一包含元素M的化合物混合均匀并在氧气气氛中进行第二次烧结，得到第二烧结产物；将第二烧结产物进行破碎、筛分和分级，得到第一正极活性材料；可选地，所述烧结温度为550℃～800℃；所述烧结时间为5h～20h；S1: uniformly mixing a lithium source, a precursor of a first positive electrode active material and a compound containing element M and performing a first sintering in an oxygen atmosphere to obtain a first sintered product; crushing the first sintered product, uniformly mixing it with another compound containing element M and performing a second sintering in an oxygen atmosphere to obtain a second sintered product; crushing, screening and grading the second sintered product to obtain a first positive electrode active material; optionally, the sintering temperature is 550° C. to 800° C.; the sintering time is 5 h to 20 h;
S2：将锂源、第二正极活性材料的前驱体和包含元素M的化合物混合均匀并在氧气气氛中进行第一次烧结，得到第一烧结产物；将第一烧结产物破碎，与另一包含元素M的化合物混合均匀并在氧气气氛中进行第二次烧结，得到第二烧结产物；将所述第二烧产物进行破碎、筛分和分级，得到第二正极活性材料；可选地，所述烧结温度为600℃～900℃；所述烧结时间为5h～20h；S2: uniformly mixing a lithium source, a precursor of a second positive electrode active material and a compound containing element M and performing a first sintering in an oxygen atmosphere to obtain a first sintered product; crushing the first sintered product, uniformly mixing it with another compound containing element M and performing a second sintering in an oxygen atmosphere to obtain a second sintered product; crushing, screening and grading the second sintered product to obtain a second positive electrode active material; optionally, the sintering temperature is 600° C. to 900° C.; the sintering time is 5 h to 20 h;
S3：将所述第一正极活性材料与所述第二正极活性材料混合，得到所述正极活性材料。S3: mixing the first positive electrode active material and the second positive electrode active material to obtain the positive electrode active material.
在任意实施方式中，在步骤S1和S2中，所述锂源选自碳酸锂、氢氧化锂和草酸锂中的至少一种。In any embodiment, in steps S1 and S2, the lithium source is selected from at least one of lithium carbonate, lithium hydroxide and lithium oxalate.
在任意实施方式中，在步骤S1和S2中，所述第一正极活性材料的前驱体和所述第二正极活性材料的前驱体各自为Ni 1-x- yCo xMn y(OH) 2和Ni 1-x-yCo xMn yCO 3中的至少一种，其中0.01≤x≤0.1，0.01≤y≤0.1。 In any embodiment, in steps S1 and S2, the precursor of the first cathode active material and the precursor of the second cathode active material are each at least one of Ni1 -x- yCoxMny (OH) 2 and Ni1 -xyCoxMnyCO3 , wherein 0.01≤x≤0.1 , 0.01≤y≤0.1 .
在任意实施方式中，在步骤S1和S2中，所述元素M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种。In any embodiment, in steps S1 and S2, the element M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce.
在任意实施方式中，在步骤S1和S2中，氧气气氛中氧气的浓度为80％以上，可选90％以上，还可选99.9％以上。In any embodiment, in steps S1 and S2, the concentration of oxygen in the oxygen atmosphere is 80% or more, optionally 90% or more, and further optionally 99.9% or more.
采用本申请的方法，可以得到一种具有高极片压实密度的正极活性材料，通过过渡金属元素掺杂及包覆，不仅可以提高材料的结构稳定性，同时还有助于改善正极活性材料的容量发挥、循环寿命及存储性能。By adopting the method of the present application, a positive electrode active material with a high electrode compaction density can be obtained. By doping and coating with transition metal elements, not only the structural stability of the material can be improved, but also the capacity, cycle life and storage performance of the positive electrode active material can be improved.
本申请的第三方面提供一种正极极片，其包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括本申请第一方面所述的正极活性材料或通过本申请第二方面所述的方法制备的正极活性材料，并且所述正极活性材料在所述正极膜层中的含量为10％重量以上，基于所述正极膜层的总重量计。The third aspect of the present application provides a positive electrode plate, which includes a positive electrode collector and a positive electrode film layer arranged on at least one surface of the positive electrode collector, the positive electrode film layer includes the positive electrode active material described in the first aspect of the present application or the positive electrode active material prepared by the method described in the second aspect of the present application, and the content of the positive electrode active material in the positive electrode film layer is more than 10% by weight, based on the total weight of the positive electrode film layer.
本申请的第四方面提供一种二次电池，其包括本申请第一方面的正极活性材料或通过本申请第二方面的方法制备的正极活性材料或本申请第三方面的正极极片。The fourth aspect of the present application provides a secondary battery, which includes the positive electrode active material of the first aspect of the present application or the positive electrode active material prepared by the method of the second aspect of the present application or the positive electrode plate of the third aspect of the present application.
本申请的第五方面提供一种用电装置，包括本申请的第四方面的二次电池。A fifth aspect of the present application provides an electrical device, comprising the secondary battery of the fourth aspect of the present application.
由于本申请的用电装置包括本申请提供的二次电池，因而至少具有与所述二次电池相同的优势。Since the electric device of the present application includes the secondary battery provided by the present application, it has at least the same advantages as the secondary battery.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
图1是由本申请实施例1的正极活性材料所制备的正极极片的切面的扫描电子显微镜图片。FIG. 1 is a scanning electron microscope image of a cross section of a positive electrode sheet prepared from the positive electrode active material of Example 1 of the present application.
图2由本申请的实施例1(2a)与对比例1(2b)和对比例2(2c)的正极活性材料所制备的二次电池的常温循环图。FIG. 2 is a normal temperature cycle diagram of a secondary battery prepared from the positive electrode active materials of Example 1 (2a) and Comparative Example 1 (2b) and Comparative Example 2 (2c) of the present application.
图3是本申请一实施方式的电池单体的示意图。FIG. 3 is a schematic diagram of a battery cell according to an embodiment of the present application.
图4是图3所示的本申请一实施方式的电池单体的分解图。FIG. 4 is an exploded view of the battery cell according to the embodiment of the present application shown in FIG. 3 .
图5是本申请一实施方式的电池模块的示意图。FIG. 5 is a schematic diagram of a battery module according to an embodiment of the present application.
图6是本申请一实施方式的电池包的示意图。FIG. 6 is a schematic diagram of a battery pack according to an embodiment of the present application.
图7是图6所示的本申请一实施方式的电池包的分解图。FIG. 7 is an exploded view of the battery pack shown in FIG. 6 according to an embodiment of the present application.
图8是本申请一实施方式的二次电池用作电源的用电装置的示意图。FIG. 8 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.
附图标记说明：Description of reference numerals:
1电池包；2上箱体；3下箱体；4电池模块；5电池单体；51壳体；52电极组件；53顶盖组件。1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell; 51 shell; 52 electrode assembly; 53 top cover assembly.
具体实施方式Detailed ways
以下，适当地参照附图详细说明具体公开了本申请的正极活性材料及其制备方法、正极极片、二次电池和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。Hereinafter, the embodiments of the positive electrode active material and preparation method thereof, positive electrode sheet, secondary battery and electric device of the present application are specifically disclosed with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果 列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。"Scope" disclosed in the present application is defined in the form of lower limit and upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope defined in this way can be including end values or excluding end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4 and 5 are listed, the following range can be fully expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just the abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。If there is no special explanation, the "include" and "comprising" mentioned in this application represent open-ended or closed-ended expressions. For example, the "include" and "comprising" may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
在现有技术中，为了增加电池的能量密度，通常会增加正极极片的压实密度。然而，极片的压实密度越大，材料颗粒之间的挤压程度 就会越大，使得极片对电解液的吸收性能变差，电解液难以浸润活性材料，导致电池的循环性能下降。在实际生产中，正极极片的压实密度通常最高能达到3.5g/cm 3。通常，进一步增加极片的压实密度并还能保持电池的循环性能变得非常困难。 In the prior art, in order to increase the energy density of the battery, the compaction density of the positive electrode plate is usually increased. However, the greater the compaction density of the plate, the greater the degree of compression between the material particles, which makes the plate's absorption performance of the electrolyte worse, and the electrolyte is difficult to infiltrate the active material, resulting in a decrease in the battery's cycle performance. In actual production, the compaction density of the positive electrode plate can usually reach up to 3.5g/ cm3 . Generally, it becomes very difficult to further increase the compaction density of the plate and maintain the battery's cycle performance.
极片的压实密度在很大程度上与粉末压实密度呈正相关，许多研究专利也肯定了这一点(例如参见CN113921782A)，但是极片压实密度的影响因素并非只有粉末压实密度一个。正极材料的比表面积越小表明单个颗粒密实程度越高，则材料填充能力差；正极材料的比表面积过大，则正极材料的活性位点多、容量高，但这样正极材料也更容易被电解液腐蚀进而导致循环寿命下降。正极材料的中值粒径Dv50也可以影响极片压实密度及其循环寿命，Dv50小则正极材料粒径分布整体向左偏移，小颗粒变多，材料填充能力变强，但是Dv50也不能太小，否则会导致微粉过多影响加工性能。因此，影响极片压实密度的因素有很多。发明人出乎意料地发现，当正极活性材料的压实密度、中值粒径和比表面积之间在满足本申请限定的条件下，可以实现至少3.7g/cm 3的极片压实密度，并且还能改善所制备的电池的电学性能。 The compaction density of the pole piece is positively correlated with the compaction density of the powder to a large extent, and many research patents have also confirmed this point (see, for example, CN113921782A), but the factor affecting the compaction density of the pole piece is not only the compaction density of the powder. The smaller the specific surface area of the positive electrode material, the higher the density of the single particle, and the poor filling capacity of the material; if the specific surface area of the positive electrode material is too large, the positive electrode material has more active sites and higher capacity, but the positive electrode material is also more easily corroded by the electrolyte, resulting in a decrease in cycle life. The median particle size Dv50 of the positive electrode material can also affect the compaction density of the pole piece and its cycle life. If Dv50 is small, the particle size distribution of the positive electrode material will shift to the left as a whole, and there will be more small particles, and the material filling capacity will become stronger, but Dv50 cannot be too small, otherwise it will cause too much micropowder to affect the processing performance. Therefore, there are many factors that affect the compaction density of the pole piece. The inventors unexpectedly discovered that when the compaction density, median particle size and specific surface area of the positive electrode active material meet the conditions specified in the present application, a pole piece compaction density of at least 3.7 g/ cm3 can be achieved, and the electrical performance of the prepared battery can also be improved.
为此，本申请的第一方面提供了一种正极活性材料，所述正极活性材料的比表面积(BET)为αm 2/g、粒径Dv50为βμm、4T粉末压实密度(CPD(4T))为γg/cm 3，并且它们满足以下关系式： To this end, the first aspect of the present application provides a positive electrode active material, wherein the specific surface area (BET) of the positive electrode active material is αm 2 /g, the particle size Dv50 is βμm, and the 4T powder compaction density (CPD(4T)) is γg/cm 3 , and they satisfy the following relationship:
-α 2+1.24α+0.136γ-0.0123β＝K，且0.75≤K≤0.85。 -α 2 +1.24α+0.136γ-0.0123β=K, and 0.75≤K≤0.85.
正极活性材料在满足本申请限定的关系式的情况下，可以实现至少3.7g/cm 3的极片压实密度，同时使得由该正极活性材料制备的二次电池具有更高的能量密度并同时还能改善循环性能。 When the positive electrode active material satisfies the relationship defined in the present application, a pole sheet compaction density of at least 3.7 g/cm 3 can be achieved, and a secondary battery prepared from the positive electrode active material has a higher energy density and improved cycle performance.
在一些实施方式中，所述正极材料具有以下通式：In some embodiments, the cathode material has the following general formula:
LiNi 1-x-y-zCo xMn yM zO 2， LiNi1 - xyzCoxMnyMzO2 , ​
其中，0.01≤x≤0.1，0.01≤y≤0.1，0≤z≤0.2，可选地，0≤z≤0.1；Wherein, 0.01≤x≤0.1, 0.01≤y≤0.1, 0≤z≤0.2, optionally, 0≤z≤0.1;
正极活性材料在满足本申请限定的关系式的情况下，能够拓宽锂 离子通道同时稳定材料结构，使正极材料具有更高的放电容量，循环寿命也大大提升，同时也可以有效预防过渡金属溶出，改善存储及安全性能。When the positive electrode active material satisfies the relationship defined in this application, it can broaden the lithium ion channel and stabilize the material structure, so that the positive electrode material has a higher discharge capacity and a greatly improved cycle life. At the same time, it can also effectively prevent the dissolution of transition metals and improve storage and safety performance.
在一些实施方式中，所述正极活性材料包括第一正极活性材料和第二正极活性材料，所述第一正极活性材料为多晶材料，其具有以下通式：In some embodiments, the positive electrode active material includes a first positive electrode active material and a second positive electrode active material, wherein the first positive electrode active material is a polycrystalline material having the following general formula:
LiNi 1-x1-y1-z1Co x1Mn y1M z1O 2， LiNi 1-x1-y1-z1 Co x1 Mn y1 M z1 O 2 ，
其中，0.01≤x 1≤0.1，0.01≤y 1≤0.1，0≤z 1≤0.2，可选地，0≤z 1≤0.1； Wherein, 0.01≤x 1 ≤0.1, 0.01≤y 1 ≤0.1, 0≤z 1 ≤0.2, optionally, 0≤z 1 ≤0.1;
M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种；M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce;
所述第二正极活性材料为类单晶材料，其具有以下通式：The second positive electrode active material is a single crystal-like material having the following general formula:
LiNi 1-x2-y2-z2Co x2Mn y2M z2O 2， LiNi 1-x2-y2-z2 Co x2 Mn y2 M z2 O 2 ，
其中，0.01≤x 2≤0.1，0.01≤y 2≤0.1，0≤z 2≤0.2，可选地，0≤z 2≤0.1； Wherein, 0.01≤x 2 ≤0.1, 0.01≤y 2 ≤0.1, 0≤z 2 ≤0.2, optionally, 0≤z 2 ≤0.1;
M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种。M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce.
在这里，本领域的技术人员可以理解，表示第一正极活性材料和第二正极活性材料以及下文中所述的前驱体的通式满足化合价之和为零。Here, those skilled in the art may understand that the general formula representing the first positive electrode active material and the second positive electrode active material and the precursor described below satisfies that the sum of the valences is zero.
在本申请中，所述多晶是指二次颗粒，由多个一次颗粒聚集在一起形成球状颗粒的状态；所述类单晶是指一次颗粒，尺寸大于0.9μm，为单个颗粒或几个一次颗粒粘连但无明显团聚的状态。In the present application, the polycrystal refers to a secondary particle, which is a state in which a plurality of primary particles are aggregated together to form a spherical particle; the quasi-single crystal refers to a primary particle, which is larger than 0.9 μm in size, and is a single particle or a state in which several primary particles are adhered but without obvious agglomeration.
除非另有说明，否则在上述化学式中，当M为两种以上元素时，上述对于z1数值范围的限定不仅是对每种作为M的元素的化学计量数的限定，也是对各个作为M的元素的化学计量数之和的限定。也即，当M为两种以上元素M1、M2……Mn时，M1、M2……Mn各自的化学计量数z11、z12……z1n各自均需落入本申请对z1限定的数值范围内，且z11、z12……z1n之和也需落入该数值范围内。Unless otherwise specified, in the above chemical formula, when M is more than two elements, the above-mentioned limitation on the numerical range of z1 is not only a limitation on the stoichiometric number of each element as M, but also a limitation on the sum of the stoichiometric numbers of each element as M. That is, when M is more than two elements M1, M2...Mn, the stoichiometric numbers z11, z12...z1n of M1, M2...Mn must each fall within the numerical range of z1 defined in the present application, and the sum of z11, z12...z1n must also fall within the numerical range.
在本申请中，可以理解，第一正极活性材料、多晶材料和多晶型团聚体是可以互换使用的，类似地，第二正极活性材料、单晶材料和类单晶小颗粒也是可以互换使用的。In the present application, it can be understood that the first positive electrode active material, polycrystalline material and polycrystalline agglomerates can be used interchangeably, and similarly, the second positive electrode active material, single crystal material and single crystal-like small particles can also be used interchangeably.
在一些实施方式中，所述正极活性材料的粒径Dv50为βμm，其中β为4.0至15，可选为4.5至10，还可选为4.7至9。In some embodiments, the particle size Dv50 of the positive electrode active material is β μm, wherein β is 4.0 to 15, optionally 4.5 to 10, and further optionally 4.7 to 9.
通过将正极活性材料的粒径控制在上述范围内，可以确保该材料拥有高容量的同时最大程度提升循环寿命。By controlling the particle size of the positive electrode active material within the above range, it is possible to ensure that the material has a high capacity while maximizing the cycle life.
在一些实施方式中，所述第一正极活性材料的Dv50为6μm至20μm，可选为7μm至18μm，还可选为8.5μm至17.8μm。In some embodiments, the Dv50 of the first positive electrode active material is 6 μm to 20 μm, optionally 7 μm to 18 μm, and further optionally 8.5 μm to 17.8 μm.
通过将第一正极活性材料的粒径控制在上述范围内，可以提供更高的容量，更好地保持循环容量。By controlling the particle size of the first positive electrode active material within the above range, a higher capacity can be provided and the cycle capacity can be better maintained.
在一些实施方式中，所述第二正极活性材料的Dv50为2μm至6μm，可选为2.5μm至4.0μm，还可选为2.6μm至3.9μm。In some embodiments, the Dv50 of the second positive active material is 2 μm to 6 μm, optionally 2.5 μm to 4.0 μm, and further optionally 2.6 μm to 3.9 μm.
通过将第二正极活性材料的粒径控制在上述范围内，可以更好地确保循环性能，确保材料的结构和动力学性能。By controlling the particle size of the second positive electrode active material within the above range, the cycle performance can be better ensured, and the structural and kinetic properties of the material can be ensured.
在一些实施方式中，所述正极活性材料的比表面积(BET)为αm 2/g，其中α为0.34至0.8，可选为0.45至0.7，还可选为0.46至0.68。 In some embodiments, the specific surface area (BET) of the positive electrode active material is αm 2 /g, wherein α is 0.34 to 0.8, optionally 0.45 to 0.7, and further optionally 0.46 to 0.68.
在一些实施方式中，所述第一正极活性材料的比表面积(BET)为0.2m 2/g至0.8m 2/g，可选为0.25m 2/g至0.6m 2/g；和/或，所述第二正极活性材料的比表面积(BET)为0.6m 2/g至1.3m 2/g，可选为0.7m 2/g至1.2m 2/g。 In some embodiments, the specific surface area (BET) of the first cathode active material is 0.2m2 /g to 0.8m2 /g, optionally 0.25m2 /g to 0.6m2 /g; and/or the specific surface area (BET) of the second cathode active material is 0.6m2 /g to 1.3m2 /g, optionally 0.7m2 /g to 1.2m2 /g.
通过将本申请的第一和第二正极活性材料的比表面积设定在上述范围内，可以延缓电解液对正极活性材料的腐蚀，确保其动力学性能并使其易于加工。By setting the specific surface areas of the first and second positive electrode active materials of the present application within the above range, the corrosion of the positive electrode active materials by the electrolyte can be delayed, the kinetic performance thereof can be ensured, and the materials can be easily processed.
在本申请中，比表面积的测试参照GB/T 19587-2017，通过美国Micromeritics公司的Tri-Star 3020型比表面积孔径分析测试仪进行氮气吸附比表面积分析测试方法测试，并用BET(Brunauer Emmett Teller)法计算得出材料的比表面积。In this application, the specific surface area test refers to GB/T 19587-2017, and the nitrogen adsorption specific surface area analysis test method is used for testing using the Tri-Star 3020 specific surface area pore size analyzer of Micromeritics, USA. The specific surface area of the material is calculated using the BET (Brunauer Emmett Teller) method.
在一些实施方式中，所述正极活性材料的4T粉末压实密度 (CPD(4T))为γg/cm 3，其中γ为3.2至4.2，可选3.3至4.0。 In some embodiments, the 4T powder compaction density (CPD(4T)) of the positive electrode active material is γ g/cm 3 , wherein γ is 3.2 to 4.2, and optionally 3.3 to 4.0.
在一些实施方式中，所述第一正极活性材料的4T粉末压实密度(CPD(4T))为3.1g/cm 3至3.7g/cm 3，可选为3.2g/cm 3至3.6g/cm 3；和/或，所述第二正极活性材料的4T粉末压实密度(CPD(4T))为3.1g/cm 3至3.7g/cm 3，可选为3.2g/cm 3至3.5g/cm 3。 In some embodiments, the 4T powder compaction density (CPD(4T)) of the first cathode active material is 3.1 g/cm 3 to 3.7 g/cm 3 , optionally 3.2 g/cm 3 to 3.6 g/cm 3 ; and/or the 4T powder compaction density (CPD(4T)) of the second cathode active material is 3.1 g/cm 3 to 3.7 g/cm 3 , optionally 3.2 g/cm 3 to 3.5 g/cm 3 .
通过将正极活性材料、第一和第二正极活性材料的4T粉末压实密度控制在上述范围内，可以确保实现本申请所需的极片压实密度。粉末压实密度一定程度上可以反映极片压实密度，在BET、粒径等不变的情况下粉末压实密度越高则极片压实密度越大。粉末压实密度可依据GB/T 24533-2009测量。By controlling the 4T powder compaction density of the positive electrode active material, the first and second positive electrode active materials within the above range, the pole piece compaction density required by the present application can be ensured. The powder compaction density can reflect the pole piece compaction density to a certain extent. When BET, particle size, etc. remain unchanged, the higher the powder compaction density, the greater the pole piece compaction density. The powder compaction density can be measured according to GB/T 24533-2009.
在一些实施方式中，所述正极活性材料的SPAN值为1.4至2.7，可选1.5至2.5，还可选为1.8至2.4，进一步可选为1.9至2.25，还可选为2.05至2.24。在本申请中，其中所述SPAN值＝(Dv90-Dv10)/Dv50。In some embodiments, the SPAN value of the positive electrode active material is 1.4 to 2.7, optionally 1.5 to 2.5, further optionally 1.8 to 2.4, further optionally 1.9 to 2.25, further optionally 2.05 to 2.24. In the present application, the SPAN value = (Dv90-Dv10)/Dv50.
在一些实施方式中，所述第一正极活性材料的SPAN值为0.9至1.5，可选为1.0至1.4，还可选为1.2至1.4；和/或，所述第二正极活性材料的SPAN值为1.0至1.7，还可选为1.3至1.65。In some embodiments, the SPAN value of the first cathode active material is 0.9 to 1.5, optionally 1.0 to 1.4, and optionally 1.2 to 1.4; and/or the SPAN value of the second cathode active material is 1.0 to 1.7, and optionally 1.3 to 1.65.
通过将正极活性材料以及第一和第二正极活性材料的SPAN值控制在上述范围内，使其具有高分散性，从而制备得到高压实密度正极片。特别是高分散性可以确保类单晶小颗粒有较好的填缝能力，使材料结合更加紧密，从而制备得到高压实密度正极片。By controlling the SPAN values of the positive electrode active material and the first and second positive electrode active materials within the above range, the positive electrode active material has high dispersibility, thereby preparing a high compaction density positive electrode sheet. In particular, high dispersibility can ensure that the single crystal-like small particles have good gap filling ability, making the materials more closely combined, thereby preparing a high compaction density positive electrode sheet.
在本申请中，按照公式SPAN＝(Dv90-Dv10)/Dv50计算得出的颗粒分散性，其中所述Dv10为样品的体积累计百分数达到10％时对应的粒径，所述Dv50为样品的体积累计百分数达到50％时对应的粒径，所述Dv90为样品的体积累计百分数达到90％时对应的粒径。In the present application, the particle dispersibility is calculated according to the formula SPAN = (Dv90-Dv10)/Dv50, wherein Dv10 is the particle size corresponding to when the cumulative volume percentage of the sample reaches 10%, Dv50 is the particle size corresponding to when the cumulative volume percentage of the sample reaches 50%, and Dv90 is the particle size corresponding to when the cumulative volume percentage of the sample reaches 90%.
在一些实施方式中，所述第一正极活性材料与第二正极活性材料的质量比为(9-1):1，可选为(6-1.5):1，还可选为(5.8-2):1，进一步可选为(5.5-2.2):1，还进一步可选为(4-2.5):1。In some embodiments, the mass ratio of the first positive electrode active material to the second positive electrode active material is (9-1):1, optionally (6-1.5):1, further optionally (5.8-2):1, further optionally (5.5-2.2):1, and further optionally (4-2.5):1.
在一些实施方式中，所述第一正极活性材料与第二正极活性材料 的质量比为(90-40):(60-10)，可选为(85-50):(50-25)，还可选为(80-60):(40-20)，所述第一正极活性材料与第二正极活性材料的质量之和按100份计。In some embodiments, the mass ratio of the first positive electrode active material to the second positive electrode active material is (90-40):(60-10), optionally (85-50):(50-25), and further optionally (80-60):(40-20), and the sum of the masses of the first positive electrode active material and the second positive electrode active material is calculated as 100 parts.
将第一和第二正极活性材料的质量比控制在上述范围内，可以提升极片的压实密度，同时能够利用第一正极活性材料的高容量、第二正极活性材料的高循环寿命的优点，实现容量和电性能最优化。By controlling the mass ratio of the first and second positive electrode active materials within the above range, the compaction density of the electrode sheet can be improved, while taking advantage of the high capacity of the first positive electrode active material and the high cycle life of the second positive electrode active material to achieve optimization of capacity and electrical performance.
本申请的第二方面还提供一种制备本申请第一方面所述的正极活性材料的方法，其包括以下步骤：The second aspect of the present application also provides a method for preparing the positive electrode active material described in the first aspect of the present application, which comprises the following steps:
将锂源、正极活性材料的前驱体混合均匀并在氧气气氛中进行烧结，得到第一烧结产物；将烧结产物进行破碎、筛分和分级，得到正极活性材料；可选地，将第一烧结产物破碎后在含有锂源的水溶液中或去离子水中进行清洗。The lithium source and the precursor of the positive electrode active material are mixed uniformly and sintered in an oxygen atmosphere to obtain a first sintered product; the sintered product is crushed, screened and graded to obtain the positive electrode active material; optionally, the first sintered product is crushed and then washed in an aqueous solution containing a lithium source or in deionized water.
可选地，将第一烧结产物与另一包含元素M的化合物混合均匀并在氧气气氛中进行第二次烧结，得到第二烧结产物；将第二烧结产物进行破碎、筛分和分级，得到正极活性材料；所述M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种；Optionally, the first sintered product is uniformly mixed with another compound containing an element M and sintered for a second time in an oxygen atmosphere to obtain a second sintered product; the second sintered product is crushed, screened and graded to obtain a positive electrode active material; wherein M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce;
可选地，所述烧结温度为550-900℃；所述烧结时间为5-20h。Optionally, the sintering temperature is 550-900° C.; and the sintering time is 5-20 h.
在一些实施方式中，其包括以下步骤：In some embodiments, it comprises the following steps:
S1：将锂源、第一正极活性材料的前驱体和包含元素M的化合物混合均匀并在氧气气氛中进行第一次烧结，得到第一烧结产物；将第一烧结产物破碎，与另一包含元素M的化合物混合均匀并在氧气气氛中进行第二次烧结，得到第二烧结产物；将第二烧结产物进行破碎、筛分和分级，得到第一正极活性材料；可选地，所述烧结温度为550℃～800℃；所述烧结时间为5h～20h；S1: uniformly mixing a lithium source, a precursor of a first positive electrode active material and a compound containing element M and performing a first sintering in an oxygen atmosphere to obtain a first sintered product; crushing the first sintered product, uniformly mixing it with another compound containing element M and performing a second sintering in an oxygen atmosphere to obtain a second sintered product; crushing, screening and grading the second sintered product to obtain a first positive electrode active material; optionally, the sintering temperature is 550° C. to 800° C.; the sintering time is 5 h to 20 h;
S2：将锂源、第二正极活性材料的前驱体和包含元素M的化合物混合均匀并在氧气气氛中进行第一次烧结，得到第一烧结产物；将第一烧结产物破碎，与另一包含元素M的化合物混合均匀并在氧气气氛中进行第二次烧结，得到第二烧结产物；将所述第二烧产物进行 破碎、筛分和分级，得到第二正极活性材料；可选地，所述烧结温度为600℃～900℃；所述烧结时间为5h～20h；S2: uniformly mixing a lithium source, a precursor of a second positive electrode active material and a compound containing element M and performing a first sintering in an oxygen atmosphere to obtain a first sintered product; crushing the first sintered product, uniformly mixing it with another compound containing element M and performing a second sintering in an oxygen atmosphere to obtain a second sintered product; crushing, screening and grading the second sintered product to obtain a second positive electrode active material; optionally, the sintering temperature is 600°C to 900°C; the sintering time is 5h to 20h;
S3：将所述第一正极活性材料与所述第二正极活性材料混合，得到所述正极活性材料。S3: mixing the first positive electrode active material and the second positive electrode active material to obtain the positive electrode active material.
在一些实施方式中，在步骤S1和S2中，所述锂源选自碳酸锂、氢氧化锂和草酸锂中的至少一种。In some embodiments, in steps S1 and S2, the lithium source is selected from at least one of lithium carbonate, lithium hydroxide and lithium oxalate.
在一些实施方式中，在步骤S1和S2中，所述第一正极活性材料的前驱体和所述第二正极活性材料的前驱体各自为Ni 1-x- yCo xMn y(OH) 2和Ni 1-x-yCo xMn yCO 3中的至少一种，其中0.01≤x≤0.1，0.01≤y≤0.1。 In some embodiments, in steps S1 and S2, the precursor of the first cathode active material and the precursor of the second cathode active material are each at least one of Ni1 -x- yCoxMny (OH) 2 and Ni1 -xyCoxMnyCO3 , wherein 0.01≤x≤0.1 , 0.01≤y≤0.1 .
在本申请中，所述第一正极活性材料的前驱体和所述第二正极活性材料的前驱体的制备可以通过现有技术中已知的方法(例如通过共沉淀反应)制得。例如，通过将硫酸镍、硫酸钴和硫酸锰配制水溶液，然后将溶液置于反应釜中并通过控制反应时间、反应温度、pH值及氨水浓度调节粒径大小及微观形貌，可以分别制备出粒径不同的第一和第二正极活性材料前驱体。In the present application, the precursor of the first positive electrode active material and the precursor of the second positive electrode active material can be prepared by a method known in the prior art (e.g., by coprecipitation reaction). For example, by preparing an aqueous solution of nickel sulfate, cobalt sulfate and manganese sulfate, and then placing the solution in a reactor and adjusting the particle size and microscopic morphology by controlling the reaction time, reaction temperature, pH value and ammonia concentration, the first and second positive electrode active material precursors with different particle sizes can be prepared respectively.
在一些实施方式中，在步骤S1中，所述锂源和第一正极活性材料的前驱体的摩尔比为(0.97–1.09):1，可选为(1–1.05):1。In some embodiments, in step S1 , the molar ratio of the lithium source to the precursor of the first positive electrode active material is (0.97-1.09):1, and can be optionally (1-1.05):1.
在一些实施方式中，在步骤S1中，包含元素M的化合物的添加量通常为100ppm至9000ppm，可选为200ppm至7000ppm，还可选为500ppm至5000ppm，进一步可选为800ppm至2000ppm，基于锂源和第一正极活性材料的前驱体的总质量计。In some embodiments, in step S1, the added amount of the compound containing element M is generally 100 ppm to 9000 ppm, optionally 200 ppm to 7000 ppm, further optionally 500 ppm to 5000 ppm, and further optionally 800 ppm to 2000 ppm, based on the total mass of the lithium source and the precursor of the first positive electrode active material.
在一些实施方式中，在步骤S1中，另一包含元素M的化合物的添加量通常为100ppm至9000ppm，可选为200ppm至7000ppm，还可选为500ppm至5000ppm，进一步可选为800ppm至2000ppm，基于锂源和第一正极活性材料的前驱体的总质量计。In some embodiments, in step S1, the addition amount of another compound containing element M is generally 100 ppm to 9000 ppm, optionally 200 ppm to 7000 ppm, further optionally 500 ppm to 5000 ppm, further optionally 800 ppm to 2000 ppm, based on the total mass of the lithium source and the precursor of the first positive electrode active material.
在一些实施方式中，在步骤S1中，第一次烧结的烧结温度为550℃至800℃，可选为650℃至750℃，烧结时间为5h至20h，可选为10h至18h。In some embodiments, in step S1, the sintering temperature of the first sintering is 550°C to 800°C, optionally 650°C to 750°C, and the sintering time is 5h to 20h, optionally 10h to 18h.
在一些实施方式中，在步骤S1中，第二次烧结的烧结温度为400℃至720℃，可选为420℃至500℃，烧结时间为5h至20h，可选为8h至15h。In some embodiments, in step S1, the sintering temperature of the second sintering is 400°C to 720°C, optionally 420°C to 500°C, and the sintering time is 5h to 20h, optionally 8h to 15h.
在一些实施方式中，在步骤S1和S2中，所述元素M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种。In some embodiments, in steps S1 and S2, the element M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce.
在一些实施方式中，所述包含元素M的化合物选自M的单质、氧化物、硼化物、磷酸盐、草酸盐、碳酸盐和硫酸盐中的一种或多种。In some embodiments, the compound containing the element M is selected from one or more of a simple substance, an oxide, a boride, a phosphate, an oxalate, a carbonate and a sulfate of M.
在一些实施方式中，在步骤S1和S2中，各步骤使用两种包含元素M的化合物，即第一种包含元素M的化合物与另一包含元素M的化合物是不同的。In some embodiments, in steps S1 and S2, two compounds containing element M are used in each step, that is, the first compound containing element M is different from the other compound containing element M.
在一些实施方式中，在步骤S1和S2中，氧气气氛中氧气的浓度为80％以上，可选90％以上，还可选99.9％以上。In some embodiments, in steps S1 and S2, the concentration of oxygen in the oxygen atmosphere is greater than 80%, optionally greater than 90%, and further optionally greater than 99.9%.
在一些实施方式中，在步骤S2中，所述锂源和第二正极活性材料的前驱体的摩尔比为(0.97–1.09):1，可选为(1–1.05):1。In some embodiments, in step S2, the molar ratio of the lithium source to the precursor of the second positive electrode active material is (0.97-1.09):1, and can be optionally (1-1.05):1.
在一些实施方式中，在步骤S2中，包含元素M的化合物的添加量通常为100ppm至9000ppm，可选为200ppm至7000ppm，还可选为300ppm至4000ppm，进一步可选为400ppm至1000ppm，基于锂源和第一正极活性材料的前驱体的总质量计。In some embodiments, in step S2, the added amount of the compound containing element M is generally 100 ppm to 9000 ppm, optionally 200 ppm to 7000 ppm, further optionally 300 ppm to 4000 ppm, and further optionally 400 ppm to 1000 ppm, based on the total mass of the lithium source and the precursor of the first positive electrode active material.
在一些实施方式中，在步骤S2中，另一包含元素M的化合物的添加量通常为100ppm至9000ppm，可选为200ppm至7000ppm，还可选为500ppm至5000ppm，进一步可选为800ppm至2000ppm，基于锂源和第一正极活性材料的前驱体的总质量计。In some embodiments, in step S2, the addition amount of another compound containing element M is generally 100 ppm to 9000 ppm, optionally 200 ppm to 7000 ppm, further optionally 500 ppm to 5000 ppm, and further optionally 800 ppm to 2000 ppm, based on the total mass of the lithium source and the precursor of the first positive electrode active material.
在一些实施方式中，在步骤S2中，第一次烧结的烧结温度为600℃至900℃，还可选为700℃至850℃，烧结时间为5h至20h，还可选为10h至18h。In some embodiments, in step S2, the sintering temperature of the first sintering is 600°C to 900°C, and may be 700°C to 850°C, and the sintering time is 5h to 20h, and may be 10h to 18h.
在一些实施方式中，在步骤S2中，锂源水溶液中锂源的浓度为2g/L至5g/L，还可选为3g/L至4g/L；和/或，所述锂源选自碳酸锂、氢氧化锂和草酸锂中的至少一种。In some embodiments, in step S2, the concentration of the lithium source in the lithium source aqueous solution is 2 g/L to 5 g/L, and can also be 3 g/L to 4 g/L; and/or, the lithium source is selected from at least one of lithium carbonate, lithium hydroxide and lithium oxalate.
在一些实施方式中，在步骤S2中，优选将第一烧结产物破碎并在含有锂源的水溶液中进行清洗，通过使用含有锂源的水溶液，可以更好地确保所制备的二次电池的循环性能，确保材料的结构和动力学性能。In some embodiments, in step S2, the first sintered product is preferably crushed and washed in an aqueous solution containing a lithium source. By using an aqueous solution containing a lithium source, the cycle performance of the prepared secondary battery can be better ensured, and the structural and dynamic properties of the material can be ensured.
在一些实施方式中，在步骤S2中，烘干温度为80℃至180℃，可选为100℃至150℃，烘干时间1小时至8小时，可选为3小时至4小时。In some embodiments, in step S2, the drying temperature is 80°C to 180°C, and may be 100°C to 150°C, and the drying time is 1 hour to 8 hours, and may be 3 hours to 4 hours.
在一些实施方式中，在步骤S2中，第二次烧结的烧结温度为400℃至820℃，可选为420℃至600℃，烧结时间为5h至20h，还可选为8h至15h。In some embodiments, in step S2, the sintering temperature of the second sintering is 400°C to 820°C, optionally 420°C to 600°C, and the sintering time is 5h to 20h, and optionally 8h to 15h.
在一些实施方式中，在步骤S3中，所述第一正极活性材料与第二正极活性材料的质量比为(9-1):1，可选为(6-1.5):1，还可选为(5.8-2):1，进一步可选为(5.5-2.2):1，还进一步可选为(4-2.5):1。In some embodiments, in step S3, the mass ratio of the first positive electrode active material to the second positive electrode active material is (9-1):1, optionally (6-1.5):1, further optionally (5.8-2):1, further optionally (5.5-2.2):1, and further optionally (4-2.5):1.
在一些实施方式中，在步骤S1、S2和S3中，其中的混合时间可根据需要进行调整，可选为0.5h至2h。In some embodiments, in steps S1, S2 and S3, the mixing time can be adjusted as needed, and can be selected to be 0.5 h to 2 h.
本申请的第三方面提供一种正极极片，其包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括本申请第一方面所述的正极活性材料或通过本申请第二方面所述的方法制备的正极活性材料，并且所述正极活性材料在所述正极膜层中的含量为10重量％以上，基于所述正极膜层的总重量计。The third aspect of the present application provides a positive electrode plate, which includes a positive electrode collector and a positive electrode film layer arranged on at least one surface of the positive electrode collector, the positive electrode film layer includes the positive electrode active material described in the first aspect of the present application or the positive electrode active material prepared by the method described in the second aspect of the present application, and the content of the positive electrode active material in the positive electrode film layer is more than 10 weight%, based on the total weight of the positive electrode film layer.
在一些实施方式中，所述正极活性材料在所述正极膜层中的含量为95-99.5重量％，可选为96-99重量％，基于所述正极膜层的总重量计。In some embodiments, the content of the positive electrode active material in the positive electrode film layer is 95-99.5% by weight, and optionally 96-99% by weight, based on the total weight of the positive electrode film layer.
在一些实施方式中，所述正极极片的面密度为17.5mg/cm 2至22mg/cm 2，可选为18.5mg/cm 2至21mg/cm 2。 In some embodiments, the surface density of the positive electrode sheet is 17.5 mg/cm 2 to 22 mg/cm 2 , and can be 18.5 mg/cm 2 to 21 mg/cm 2 .
在本申请中，所述正极膜层的面密度具有本领域公知的含义，可采用本领域已知的方法测试。例如取单面涂布且经冷压后的正极极片(若是双面涂布的正极极片，可先擦拭掉其中一面的正极活性材料层)，冲切成面积为S1的小圆片，称其重量，记录为M1。然后将 上述称重后的正极极片的正极活性材料层擦拭掉，称量正极集流体的重量，记录为M0，正极活性材料层的面密度＝(正极极片的重量M1－正极集流体的重量M0)/S1。为了确保测试结果的准确性，可以测试多组(例如10组)待测样品，计算平均值作为测试结果。In the present application, the surface density of the positive electrode film layer has a meaning well known in the art and can be tested by methods known in the art. For example, take a single-sided coated and cold-pressed positive electrode sheet (if it is a double-sided coated positive electrode sheet, the positive electrode active material layer on one side can be wiped off first), punch it into small discs with an area of S1, weigh it, and record it as M1. Then wipe off the positive electrode active material layer of the above-mentioned weighed positive electrode sheet, weigh the weight of the positive electrode collector, and record it as M0. The surface density of the positive electrode active material layer = (weight of the positive electrode sheet M1 - weight of the positive electrode collector M0) / S1. In order to ensure the accuracy of the test results, multiple groups (for example, 10 groups) of samples to be tested can be tested, and the average value is calculated as the test result.
在一些实施方式中，所述正极极片的压实密度为3.7g/cm 3至4g/cm 3，可选为3.7g/cm 3至3.85g/cm 3。 In some embodiments, the compaction density of the positive electrode sheet is 3.7 g/cm 3 to 4 g/cm 3 , and can be 3.7 g/cm 3 to 3.85 g/cm 3 .
在一些实施方式中，所述正极极片的延展率为0.7％至0.8％。In some embodiments, the elongation of the positive electrode sheet is 0.7% to 0.8%.
本申请的第四方面提供一种二次电池，其包括本申请第一方面的正极活性材料或通过本申请第二方面的方法制备的正极活性材料或本申请第三方面的正极极片。The fourth aspect of the present application provides a secondary battery, which includes the positive electrode active material of the first aspect of the present application or the positive electrode active material prepared by the method of the second aspect of the present application or the positive electrode plate of the third aspect of the present application.
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
以下适当参照附图对本申请的二次电池进行说明。二次电池可以包括电池单体的形式，可以包括电池模块的形式，可以包括电池包的形式。The secondary battery of the present application is described below with reference to the accompanying drawings as appropriate. The secondary battery may be in the form of a battery cell, a battery module, or a battery pack.
本申请的一个实施方式中，提供一种电池单体。In one embodiment of the present application, a battery cell is provided.
通常情况下，电池单体包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。Generally, a battery cell includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
[正极极片][Positive electrode]
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述正极膜层包括本申请第一方面的正极活性材料。The positive electrode plate includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes the positive electrode active material of the first aspect of the present application.
作为示例，正极集流体具有在其自身厚度方向相对的两个表面， 正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料(铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
在一些实施方式中，除了本申请第一方面的正极活性材料之外，正极活性材料还可采用本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。 In some embodiments, in addition to the positive electrode active material of the first aspect of the present application, the positive electrode active material may also be a positive electrode active material for a battery known in the art. As an example, the positive electrode active material may include at least one of the following materials: a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to , lithium cobalt oxide (such as LiCoO2 ), lithium nickel oxide (such as LiNiO2 ), lithium manganese oxide (such as LiMnO2 , LiMn2O4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi1 / 3Co1 / 3Mn1 / 3O2 (also referred to as NCM333 ), LiNi0.5Co0.2Mn0.3O2 (also referred to as NCM523 ) , LiNi0.5Co0.25Mn0.25O2 (also referred to as NCM211 ) , LiNi0.6Co0.2Mn0.2O2 (also referred to as NCM622 ), LiNi0.8Co0.1Mn0.1O2 (also referred to as NCM811 ), lithium nickel cobalt aluminum oxide ( such as LiNi 0.85 Co 0.15 Al 0.05 O 2 ) and at least one of modified compounds thereof. Examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏 氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。In some embodiments, the positive electrode film layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.
在一些实施方式中，所述粘结剂占所述正极膜层的质量百分比为0.1％至4％，可选0.5％至2％。In some embodiments, the binder accounts for 0.1% to 4% by mass of the positive electrode film layer, and optionally 0.5% to 2% by mass.
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。In some embodiments, the positive electrode film layer may further include a conductive agent, which may include, for example, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
在一些实施方式中，所述导电剂占所述正极膜层的质量百分比为0.1％至4％，可选为0.5％至2％。In some embodiments, the conductive agent accounts for 0.1% to 4% by mass of the positive electrode film layer, and can be optionally 0.5% to 2% by mass.
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料；将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，即可得到正极极片。In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.
[负极极片][Negative electrode]
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括负极活性材料。The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料(铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等)形成在高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)上而形成。In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).
在一些实施方式中，负极活性材料可采用本领域公知的用于电池 的负极活性材料。作为示例，负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些负极活性材料可以仅单独使用一种，也可以将两种以上组合使用。In some embodiments, the negative electrode active material may be a negative electrode active material for a battery known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.
在一些实施方式中，所述负极活性材料占所述负极膜层的质量百分比为75％至99％，可选80％至98％。In some embodiments, the mass percentage of the negative electrode active material in the negative electrode film layer is 75% to 99%, and optionally 80% to 98%.
在一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。In some embodiments, the negative electrode film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
在一些实施方式中，所述粘结剂占所述负极膜层的质量百分比为0.1％至3.5％，可选0.5％至2.5％。In some embodiments, the binder accounts for 0.1% to 3.5% by mass of the negative electrode film layer, and optionally 0.5% to 2.5% by mass.
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。In some embodiments, the negative electrode film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers.
在一些实施方式中，所述导电剂占所述负极膜层的质量百分比为0.04％至5％，可选为0.5％至3％。In some embodiments, the conductive agent accounts for 0.04% to 5% by mass of the negative electrode film layer, and can be optionally 0.5% to 3% by mass.
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料；将负极浆料涂覆在负极集流体上，经烘干、冷压等工序后，即可得到负极极片。In some embodiments, the negative electrode sheet can be prepared in the following manner: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.
[电解质][Electrolytes]
电解质在正极极片和负极极片之间起到传导离子的作用。本申请 对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.
在一些实施方式中，电解质盐可选自六氟磷酸锂、四氟硼酸锂、高氯酸锂、六氟砷酸锂、双氟磺酰亚胺锂、双三氟甲磺酰亚胺锂、三氟甲磺酸锂、二氟磷酸锂、二氟草酸硼酸锂、二草酸硼酸锂、二氟二草酸磷酸锂及四氟草酸磷酸锂中的至少一种。In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.
在一些实施方式中，溶剂可选自碳酸亚乙酯、碳酸亚丙酯、碳酸甲乙酯、碳酸二乙酯、碳酸二甲酯、碳酸二丙酯、碳酸甲丙酯、碳酸乙丙酯、碳酸亚丁酯、氟代碳酸亚乙酯、甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸丙酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、丁酸甲酯、丁酸乙酯、1,4-丁内酯、环丁砜、二甲砜、甲乙砜及二乙砜中的至少一种。In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.
在一些实施方式中，电解质盐在非水电解液中的浓度为例如0.3mol/L(摩尔/升)以上，可选为0.7mol/L以上，可选为1.7mol/L以下，还可选为1.2mol/L以下。In some embodiments, the concentration of the electrolyte salt in the non-aqueous electrolyte is, for example, 0.3 mol/L (mole/liter) or more, optionally 0.7 mol/L or more, optionally 1.7 mol/L or less, and further optionally 1.2 mol/L or less.
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。In some embodiments, the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
[隔离膜][Isolation film]
在一些实施方式中，电池单体中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。In some embodiments, the battery cell further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。In some embodiments, the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.
在一些实施方式中，电池单体可包括外包装。该外包装可用于封装上述电极组件及电解质。In some embodiments, the battery cell may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.
在一些实施方式中，电池单体的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
本申请对电池单体的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图3是作为一个示例的方形结构的电池单体5。The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square or any other shape. For example, FIG3 is a battery cell 5 of a square structure as an example.
在一些实施方式中，参照图4，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。电池单体5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。In some embodiments, referring to FIG. 4 , the outer package may include a shell 51 and a cover plate 53. Among them, the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to specific actual needs.
在一些实施方式中，电池单体可以组装成电池模块，电池模块所含电池单体的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。In some embodiments, battery cells may be assembled into a battery module. The number of battery cells contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.
图5是作为一个示例的电池模块4。参照图5，在电池模块4中，多个电池单体5可以是沿电池模块4的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个电池单体5进行固定。FIG5 is a battery module 4 as an example. Referring to FIG5 , in the battery module 4, a plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.
可选地，电池模块4还可以包括具有容纳空间的外壳，多个电池单体5容纳于该容纳空间。Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.
在一些实施方式中，上述电池单体可以组装成电池包。在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块 的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。In some embodiments, the battery cells can be assembled into a battery pack. In some embodiments, the battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.
图6和图7是作为一个示例的电池包1。参照图6和图7，在电池包1中可以包括电池箱和设置于电池箱中的多个电池模块4。电池箱包括上箱体2和下箱体3，上箱体2能够盖设于下箱体3，并形成用于容纳电池模块4的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。FIG6 and FIG7 are battery packs 1 as an example. Referring to FIG6 and FIG7 , the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be covered on the lower box body 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池。所述二次电池可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能***等，但不限于此。In addition, the present application also provides an electric device, the electric device includes the secondary battery provided in the present application. The secondary battery can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto.
作为所述用电装置，可以根据其使用需求来选择二次电池。As the electrical device, a secondary battery can be selected according to its usage requirements.
图8是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。FIG8 is an example of an electric device. The electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the electric device's requirements for high power and high energy density of secondary batteries, a battery pack or a battery module may be used.
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求轻薄化，可以采用电池单体作为电源。Another example of a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be light and thin, and a battery cell may be used as a power source.
实施例Example
以下，说明本申请的实施例。下面描述的实施例是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used that do not indicate the manufacturer are all conventional products that can be obtained commercially.
一、二次电池的制备1. Preparation of secondary batteries
实施例1Example 1
1.正极活性材料的制备1. Preparation of positive electrode active materials
将摩尔比为1.03:1的碳酸锂和第一正极活性材料的前驱体P0(Ni 0.92Co 0.04Mn 0.04(OH) 2，Dv50＝20.5μm)的混合物和1000ppm的氧化锆置于高混机中混合均匀并在氧气气氛中730℃烧结15h，得到第一烧结产物P1；将P1破碎并与1000ppm的氧化铝混合均匀，在氧气气氛中450℃烧结10h，得到第二烧结产物P2；将P2进行机械破碎、筛分、分级，即可得到第一正极活性材料，多晶型团聚体P，粒径Dv50＝19.6μm，SPAN＝1.23。 A mixture of lithium carbonate and a precursor of the first positive electrode active material P0 (Ni 0.92 Co 0.04 Mn 0.04 (OH) 2 , Dv50=20.5 μm) in a molar ratio of 1.03:1 and 1000 ppm of zirconium oxide are placed in a high mixer, mixed evenly, and sintered at 730° C. for 15 h in an oxygen atmosphere to obtain a first sintered product P1; P1 is crushed and mixed evenly with 1000 ppm of aluminum oxide, and sintered at 450° C. for 10 h in an oxygen atmosphere to obtain a second sintered product P2; P2 is mechanically crushed, sieved, and graded to obtain a first positive electrode active material, a polycrystalline agglomerate P, with a particle size of Dv50=19.6 μm and SPAN=1.23.
将摩尔比为1.03:1的碳酸锂、第二正极活性材料的前驱体S0(Ni 0.92Co 0.04Mn 0.04(OH) 2，Dv50＝4.5μm)和500ppm的氧化锶置于高混机中混合均匀并在氧气气氛中820℃烧结15h，得到第一烧结产物S1；将S1破碎并在含有氢氧化锂的水溶液(浓度3.5g/L)中进行清洗，烘干后与1000ppm的氧化铝混合均匀，然后在氧气气氛中480℃烧结10h，得到第二烧结产物S2；将S2进行破碎、筛分、分级，即可得到第二正极活性材料，类单晶小颗粒S，粒径Dv50＝5.7μm，SPAN＝1.44。 Lithium carbonate with a molar ratio of 1.03:1, the precursor S0 (Ni 0.92 Co 0.04 Mn 0.04 (OH) 2 , Dv50 = 4.5 μm) of the second positive electrode active material and 500 ppm of strontium oxide are placed in a high-speed mixer and mixed evenly, and sintered at 820° C. for 15 h in an oxygen atmosphere to obtain a first sintered product S1; S1 is crushed and washed in an aqueous solution containing lithium hydroxide (concentration 3.5 g/L), dried and mixed evenly with 1000 ppm of aluminum oxide, and then sintered at 480° C. for 10 h in an oxygen atmosphere to obtain a second sintered product S2; S2 is crushed, sieved and graded to obtain a second positive electrode active material, single-crystal-like small particles S with a particle size of Dv50 = 5.7 μm and SPAN = 1.44.
将上述多晶型团聚体P与类单晶小颗粒S按照质量比75:25混合均匀,得到本申请的正极活性材料。The polycrystalline agglomerates P and the single-crystal-like small particles S are uniformly mixed in a mass ratio of 75:25 to obtain the positive electrode active material of the present application.
2.正极极片2. Positive electrode
将上述正极活性材料、导电剂乙炔黑(SP)与粘结剂聚偏氟乙烯(PVDF)按照97：1.5：1.5的质量比投入5L搅拌罐中进行30min的预混合，最后加入溶剂N-甲基吡咯烷酮(NMP)在抽真空环境下进行快速搅拌形成浆料，浆料的固含量为70重量％。将浆料均匀、双面涂覆于厚度为12μm的铝箔上，涂覆后的极片经过100℃烘箱干燥半小时后取出，面密度为19.5mg/cm 2，压实密度为3.70g/cm 3。 The positive electrode active material, conductive agent acetylene black (SP) and binder polyvinylidene fluoride (PVDF) were put into a 5L stirring tank at a mass ratio of 97:1.5:1.5 for premixing for 30 minutes, and finally N-methylpyrrolidone (NMP) was added as solvent and stirred rapidly under vacuum to form slurry with a solid content of 70% by weight. The slurry was evenly coated on both sides of an aluminum foil with a thickness of 12μm. The coated electrode was taken out after drying in an oven at 100℃ for half an hour, with a surface density of 19.5mg/ cm2 and a compacted density of 3.70g/ cm3 .
3.负极极片3. Negative electrode
将负极活性材料人造石墨、硬碳、导电剂乙炔黑、粘结剂丁苯橡胶(SBR)、增稠剂羧甲基纤维素钠(CMC-Na)按照重量比90:5:2:2:1在去离子水中混合均匀后，涂覆于铜箔上烘干、冷压，得到负极极片，涂覆量为12.5g/cm 2。 The negative electrode active material artificial graphite, hard carbon, conductive agent acetylene black, binder styrene butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) were mixed uniformly in deionized water at a weight ratio of 90:5:2:2:1, coated on copper foil, dried, and cold pressed to obtain a negative electrode sheet with a coating amount of 12.5 g/ cm2 .
4.电解液4. Electrolyte
将碳酸亚乙酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)以体积比1:1:1混合，然后将LiPF 6均匀溶解在上述溶液中得到电解液，其中LiPF 6的浓度为1mol/L。 Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1, and then LiPF6 is uniformly dissolved in the above solution to obtain an electrolyte, wherein the concentration of LiPF6 is 1 mol/L.
5.隔离膜5. Isolation film
以聚乙烯(PE)多孔聚合薄膜作为隔离膜。A polyethylene (PE) porous polymer film is used as the isolation membrane.
将上述正极极片、隔离膜、负极极片按顺序叠好，使隔离膜处于正负极中间起到隔离的作用，并卷绕得到裸电芯。将裸电芯置于外包装中，注入电解液并封装，得到全电池。全电池的长×宽×高＝90mm×30mm×60mm，电池的群裕度为97％。The positive electrode sheet, separator, and negative electrode sheet are stacked in order, so that the separator is between the positive and negative electrodes to play a role of isolation, and then wound to obtain a bare cell. The bare cell is placed in an outer package, injected with electrolyte and packaged to obtain a full battery. The length × width × height of the full battery = 90mm × 30mm × 60mm, and the battery group margin is 97%.
实施例2-7Embodiment 2-7
其制备方法与实施例1基本上相同，但仅改变其中的部分参数，具体变量参见表1和2。The preparation method is basically the same as that of Example 1, but only some parameters are changed. For specific variables, see Tables 1 and 2.
实施例8Example 8
其制备方法与实施例1类似，不同之处在于，其中仅使用第一正极活性材料且所述第一正极活性材料的参数不同，具体参见表2。The preparation method is similar to that of Example 1, except that only the first positive electrode active material is used and the parameters of the first positive electrode active material are different, see Table 2 for details.
对比例1Comparative Example 1
其制备方法与实施例1类似，不同之处在于，其中第一正极活性 材料与第二正极活性材料的混合比以及它们的参数不同，具体参见表1和2。The preparation method is similar to that of Example 1, except that the mixing ratio of the first positive electrode active material and the second positive electrode active material and their parameters are different, see Tables 1 and 2 for details.
对比例2Comparative Example 2
其制备方法与实施例1类似，不同之处在于，其中仅使用第一正极活性材料且所述第一正极活性材料的参数不同，具体参见表2。The preparation method is similar to that of Example 1, except that only the first positive electrode active material is used and the parameters of the first positive electrode active material are different, see Table 2 for details.
二、相关参数的测试2. Testing of related parameters
正极极片的压实密度和延展率的测试方法Test method for compaction density and elongation of positive electrode sheets
在极片长度方向平行标记三条长度为100cm的线段记为L0，过辊冷压后测试长度为L1；取过辊冷压后直径D为50mm的小圆片，测量其厚度记为H，其重量记为G。压实密度计算公式PD＝G/(A×H)，A为小圆片面积；长度方向延展率计算公式ΔEL％＝(L1-L0)/L0×100％。Three 100cm long lines are marked in parallel in the length direction of the pole piece, and are marked as L0. The length after roller cold pressing is L1. Take a small disc with a diameter D of 50mm after roller cold pressing, measure its thickness and mark it as H, and its weight as G. The compaction density calculation formula is PD = G/(A×H), where A is the area of the small disc; the elongation in the length direction is calculated by ΔEL% = (L1-L0)/L0×100%.
比表面积测试Specific surface area test
比表面积的测试参照GB/T 19587-2017，通过美国Micromeritics公司的Tri-Star 3020型比表面积孔径分析测试仪进行氮气吸附比表面积分析测试方法测试，并用BET(Brunauer Emmett Teller)法计算得出材料的比表面积。测试结果参见表1和2。The specific surface area test was carried out according to GB/T 19587-2017, using the Tri-Star 3020 specific surface area pore size analyzer from Micromeritics, USA, to perform nitrogen adsorption specific surface area analysis test method, and the specific surface area of the material was calculated using the BET (Brunauer Emmett Teller) method. The test results are shown in Tables 1 and 2.
颗粒分散度测试——粒径测试Particle dispersion test - particle size test
根据GB/T 19077.1-2016/ISO 13320:2009(粒度分布激光衍射法)测定正极活性材料的粒径。取一洁净烧杯，加入适量的上述正极活性材料，加入适量纯水，超声120W/5min确保材料粉末在水中完全分散。溶液倒入激光粒度分析仪(马尔文公司，型号：Mastersizer3000)的进样塔后随溶液循环到测试光路***，颗粒在激光束的照射下，通过接受和测量散向光的能量分布可得到颗粒的粒度分布特征(遮光度：8-12％)，读取Dv10、Dv50、Dv90的相应数值。The particle size of the positive electrode active material is determined according to GB/T 19077.1-2016/ISO 13320:2009 (laser diffraction method for particle size distribution). Take a clean beaker, add an appropriate amount of the above-mentioned positive electrode active material, add an appropriate amount of pure water, and use ultrasound at 120W/5min to ensure that the material powder is completely dispersed in the water. After the solution is poured into the injection tower of the laser particle size analyzer (Malvern Company, model: Mastersizer3000), it circulates to the test optical path system with the solution. The particles are irradiated by the laser beam, and the particle size distribution characteristics of the particles (shading degree: 8-12%) can be obtained by receiving and measuring the energy distribution of the scattered light, and the corresponding values of Dv10, Dv50, and Dv90 are read.
按照公式SPAN＝(Dv90-Dv10)/Dv50计算得出的颗粒分散度，测试结果参见表1和2。The particle dispersion was calculated according to the formula SPAN = (Dv90 - Dv10) / Dv50. The test results are shown in Tables 1 and 2.
4T粉末压实密度测试4T powder compaction density test
根据GB/T 24533-2009测定正极活性材料4T压力下(即在4吨压力下)的压实密度。取一定量的正极活性材料的粉末放于压实专用模具中,然后将模具放在压实密度仪器上。施加4T的压力，在设备上读出4T压力下粉末的厚度(卸压后的厚度)，通过ρ＝m/v，计算出压实密度。测试结果参见表1和2。The compaction density of the positive electrode active material under 4T pressure (i.e., under 4 tons of pressure) is determined according to GB/T 24533-2009. A certain amount of the powder of the positive electrode active material is placed in a special compaction mold, and then the mold is placed on the compaction density instrument. A pressure of 4T is applied, and the thickness of the powder under 4T pressure (thickness after pressure relief) is read on the device, and the compaction density is calculated by ρ=m/v. The test results are shown in Tables 1 and 2.
K值的计算Calculation of K value
通过测定正极活性材料的比表面积(BET)α(单位m 2/g)、粒径Dv50(单位μm)β、4T粉末压实密度(CPD(4T))γ(单位g/cm 3)，按照以下公式计算K值：K＝-α 2+1.24α+0.136γ-0.0123β，计算结果参见表2。 By measuring the specific surface area (BET) α (unit: m 2 /g), particle size Dv50 (unit: μm) β, and 4T powder compaction density (CPD(4T)) γ (unit: g/cm 3 ) of the positive electrode active material, the K value was calculated according to the following formula: K=-α 2 +1.24α+0.136γ-0.0123β. The calculation results are shown in Table 2.
三、样品形貌表征3. Sample morphology characterization
采用德国ZEISS公司的场发射扫描电子显微镜(Sigma300)表征由实施例1的正极活性材料所制成的正极极片的切面的形貌，结果如图1所示。The morphology of the cross section of the positive electrode sheet made of the positive electrode active material of Example 1 was characterized using a field emission scanning electron microscope (Sigma300) from ZEISS, Germany. The result is shown in FIG1 .
四、电池的性能测试4. Battery performance test
常温循环保持率(25℃)，标称容量215mAh/g，(1)将所制备的全电池放进恒温箱静置30min，0.33C恒流放电至2.8V，(2)静置5min，0.33C恒流充电至4.25V而后0.05C恒压至4.25V，静置5min，(3)0.33C恒流放电至2.8V，此时读取容量值记为初始容量C0。重复(2)-(3)得到第二圈容量数据C1，C1/C0即可得到循环保持率。测试结果参见表3。Normal temperature cycle retention rate (25°C), nominal capacity 215mAh/g, (1) put the prepared full battery into a thermostat and let it stand for 30 minutes, discharge at 0.33C constant current to 2.8V, (2) let it stand for 5 minutes, charge at 0.33C constant current to 4.25V and then at 0.05C constant voltage to 4.25V, let it stand for 5 minutes, (3) discharge at 0.33C constant current to 2.8V, at this time read the capacity value and record it as the initial capacity C0. Repeat (2)-(3) to obtain the second cycle capacity data C1, C1/C0 can get the cycle retention rate. The test results are shown in Table 3.
表1.实施例1-7和对比例1的第一正极活性材料(P)和第二正极活性材料(S)的相关参数。Table 1. Relevant parameters of the first positive electrode active material (P) and the second positive electrode active material (S) of Examples 1-7 and Comparative Example 1.
Figure PCTCN2022127059-appb-000001
Figure PCTCN2022127059-appb-000001
表2.实施例1-8和对比例1-2所制备的正极活性材料以及所得正极极片的相关参数Table 2. Related parameters of the positive electrode active materials prepared in Examples 1-8 and Comparative Examples 1-2 and the obtained positive electrode sheets
Figure PCTCN2022127059-appb-000002
Figure PCTCN2022127059-appb-000002
由表2可以看出，当K值在本申请的范围内时，可以实现至少3.7g/cm 3的极片压实密度，这是出乎意料的。 It can be seen from Table 2 that when the K value is within the range of the present application, a pole piece compaction density of at least 3.7 g/cm 3 can be achieved, which is unexpected.
表3实施例1-8和对比例1-2的二次电池的性能测试结果Table 3 Performance test results of secondary batteries of Examples 1-8 and Comparative Examples 1-2
 The 常温循环保持率，50圈Normal temperature cycle retention rate, 50 cycles
实施例1Example 1 0.98780.9878
实施例2Example 2 0.98740.9874
实施例3Example 3 0.98760.9876
实施例4Example 4 0.98850.9885
实施例5Example 5 0.98560.9856
实施例6Example 6 0.98440.9844
实施例7Example 7 0.98680.9868
实施例8Example 8 0.98330.9833
对比例1Comparative Example 1 0.96940.9694
对比例2Comparative Example 2 0.98210.9821
由表3可以看出，通过使用本申请的正极活性材料制备的二次电池不仅具有较好的极片压实密度，实现了更高的能量密度，而且其也可以实现较好的循环性能。It can be seen from Table 3 that the secondary battery prepared by using the positive electrode active material of the present application not only has a better electrode compaction density and achieves a higher energy density, but also can achieve better cycle performance.
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims (21)

  1. 正极活性材料，所述正极活性材料的比表面积为αm 2/g、粒径Dv50为βμm、4T粉末压实密度为γg/cm 3，并且它们满足以下关系式： A positive electrode active material, wherein the specific surface area of the positive electrode active material is αm 2 /g, the particle size Dv50 is βμm, the 4T powder compaction density is γg/cm 3 , and they satisfy the following relationship:
    -α 2+1.24α+0.136γ-0.0123β＝K，且0.75≤K≤0.85。 -α 2 +1.24α+0.136γ-0.0123β=K, and 0.75≤K≤0.85.
  2. 根据权利要求1所述的正极活性材料，其中，所述正极材料具有以下通式：The positive electrode active material according to claim 1, wherein the positive electrode material has the following general formula:
    LiNi 1-x-y-zCo xMn yM zO 2， LiNi1 - xyzCoxMnyMzO2 , ​
    其中，0.01≤x≤0.1，0.01≤y≤0.1，0≤z≤0.2，可选地，0≤z≤0.1；Wherein, 0.01≤x≤0.1, 0.01≤y≤0.1, 0≤z≤0.2, optionally, 0≤z≤0.1;
  3. 根据权利要求1或2所述的正极活性材料，其中，所述正极活性材料包括第一正极活性材料和第二正极活性材料，所述第一正极活性材料为多晶材料，其具有以下通式：The positive electrode active material according to claim 1 or 2, wherein the positive electrode active material comprises a first positive electrode active material and a second positive electrode active material, and the first positive electrode active material is a polycrystalline material having the following general formula:
    LiNi 1-x1-y1-z1Co x1Mn y1M z1O 2， LiNi 1-x1-y1-z1 Co x1 Mn y1 M z1 O 2 ，
    其中，0.01≤x 1≤0.1，0.01≤y 1≤0.1，0≤z 1≤0.2， Among them, 0.01≤x 1 ≤0.1, 0.01≤y 1 ≤0.1, 0≤z 1 ≤0.2,
    M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种；M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce;
    所述第二正极活性材料为类单晶材料，其具有以下通式：The second positive electrode active material is a single crystal-like material having the following general formula:
    LiNi 1-x2-y2-z2Co x2Mn y2M z2O 2， LiNi 1-x2-y2-z2 Co x2 Mn y2 M z2 O 2 ,
    其中，0.01≤x 2≤0.1，0.01≤y 2≤0.1，0≤z 2≤0.2， Among them, 0.01≤x 2 ≤0.1, 0.01≤y 2 ≤0.1, 0≤z 2 ≤0.2,
    M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种。M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce.
  4. 根据权利要求1至3中任一项所述的正极活性材料，其中所述正极活性材料的粒径Dv50为βμm，其中β为4.0至15，可选为4.5至10。The positive electrode active material according to any one of claims 1 to 3, wherein the particle size Dv50 of the positive electrode active material is β μm, wherein β is 4.0 to 15, and optionally 4.5 to 10.
  5. 根据权利要求1至4中任一项所述的正极活性材料，其中所述第一正极活性材料的Dv50为6μm至20μm，可选为7μm至18μm。The positive electrode active material according to any one of claims 1 to 4, wherein the Dv50 of the first positive electrode active material is 6 μm to 20 μm, and optionally 7 μm to 18 μm.
  6. 根据权利要求1至5中任一项所述的正极活性材料，其中所述第二正极活性材料的Dv50为2μm至6μm，可选为2.5μm至4.0 μm。The positive electrode active material according to any one of claims 1 to 5, wherein the Dv50 of the second positive electrode active material is 2 μm to 6 μm, and optionally 2.5 μm to 4.0 μm.
  7. 根据权利要求1至6中任一项所述的正极活性材料，其中所述正极活性材料的比表面积为αm 2/g，其中α为0.34至0.8，可选为0.45至0.7。 The positive electrode active material according to any one of claims 1 to 6, wherein the specific surface area of the positive electrode active material is αm 2 /g, wherein α is 0.34 to 0.8, and optionally 0.45 to 0.7.
  8. 根据权利要求1至7中任一项所述的正极活性材料，其中所述第一正极活性材料的比表面积为0.2m 2/g至0.8m 2/g；和/或，所述第二正极活性材料的比表面积为0.6m 2/g至1.3m 2/g。 The cathode active material according to any one of claims 1 to 7, wherein the specific surface area of the first cathode active material is 0.2 m 2 /g to 0.8 m 2 /g; and/or the specific surface area of the second cathode active material is 0.6 m 2 /g to 1.3 m 2 /g.
  9. 根据权利要求1至8中任一项所述的正极活性材料，其中所述正极活性材料的4T粉末压实密度为γg/cm 3，其中γ为3.2至4.2，可选3.3至4.0。 The positive electrode active material according to any one of claims 1 to 8, wherein the 4T powder compaction density of the positive electrode active material is γ g/cm 3 , wherein γ is 3.2 to 4.2, and optionally 3.3 to 4.0.
  10. 根据权利要求1至9中任一项所述的正极活性材料，其中所述第一正极活性材料的4T粉末压实密度为3.1g/cm 3至3.7g/cm 3；和/或，所述第二正极活性材料的4T粉末压实密度为3.1g/cm 3至3.7g/cm 3。 The cathode active material according to any one of claims 1 to 9, wherein the 4T powder compaction density of the first cathode active material is 3.1 g/cm 3 to 3.7 g/cm 3 ; and/or the 4T powder compaction density of the second cathode active material is 3.1 g/cm 3 to 3.7 g/cm 3 .
  11. 根据权利要求1至10中任一项所述的正极活性材料，其中所述正极活性材料的SPAN值为1.4至2.7，可选1.5至2.5。The positive electrode active material according to any one of claims 1 to 10, wherein the SPAN value of the positive electrode active material is 1.4 to 2.7, and optionally 1.5 to 2.5.
  12. 根据权利要求1至11中任一项所述的正极活性材料，其中所述第一正极活性材料的SPAN值为0.9至1.5；和/或，所述第二正极活性材料的SPAN值为1.0至1.7。The positive electrode active material according to any one of claims 1 to 11, wherein the SPAN value of the first positive electrode active material is 0.9 to 1.5; and/or the SPAN value of the second positive electrode active material is 1.0 to 1.7.
  13. 根据权利要求1至12中任一项所述的正极活性材料，其中所述第一正极活性材料与第二正极活性材料的质量比为(9-1):1，可选为(6-1.5):1。The positive electrode active material according to any one of claims 1 to 12, wherein the mass ratio of the first positive electrode active material to the second positive electrode active material is (9-1):1, and can be optionally (6-1.5):1.
  14. 一种正极活性材料的制备方法，其包括以下步骤：A method for preparing a positive electrode active material comprises the following steps:
    将锂源、正极活性材料的前驱体混合均匀并在氧气气氛中进行烧结，得到第一烧结产物；将烧结产物进行破碎、筛分和分级，得到正极活性材料；可选地，将第一烧结产物破碎后在含有锂源的水溶液中或去离子水中进行清洗。The lithium source and the precursor of the positive electrode active material are mixed uniformly and sintered in an oxygen atmosphere to obtain a first sintered product; the sintered product is crushed, screened and graded to obtain the positive electrode active material; optionally, the first sintered product is crushed and then washed in an aqueous solution containing a lithium source or in deionized water.
    可选地，将第一烧结产物与另一包含元素M的化合物混合均匀并在氧气气氛中进行第二次烧结，得到第二烧结产物；将第二烧结产 物进行破碎、筛分和分级，得到正极活性材料；所述M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种；Optionally, the first sintered product is uniformly mixed with another compound containing an element M and sintered for a second time in an oxygen atmosphere to obtain a second sintered product; the second sintered product is crushed, screened and graded to obtain a positive electrode active material; the M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce;
    可选地，所述烧结温度为550-900℃；所述烧结时间为5-20h。Optionally, the sintering temperature is 550-900° C.; and the sintering time is 5-20 h.
  15. 根据权利要求14的制备方法，其包括以下步骤：The preparation method according to claim 14, comprising the following steps:
    S1：将锂源、第一正极活性材料的前驱体和包含元素M的化合物混合均匀并在氧气气氛中进行第一次烧结，得到第一烧结产物；将第一烧结产物破碎，与另一包含元素M的化合物混合均匀并在氧气气氛中进行第二次烧结，得到第二烧结产物；将第二烧结产物进行破碎、筛分和分级，得到第一正极活性材料；可选地，所述烧结温度为550℃～800℃；所述烧结时间为5h～20h；S1: uniformly mixing a lithium source, a precursor of a first positive electrode active material and a compound containing element M and performing a first sintering in an oxygen atmosphere to obtain a first sintered product; crushing the first sintered product, uniformly mixing it with another compound containing element M and performing a second sintering in an oxygen atmosphere to obtain a second sintered product; crushing, screening and grading the second sintered product to obtain a first positive electrode active material; optionally, the sintering temperature is 550° C. to 800° C.; the sintering time is 5 h to 20 h;
    S2：将锂源、第二正极活性材料的前驱体和包含元素M的化合物混合均匀并在氧气气氛中进行第一次烧结，得到第一烧结产物；将第一烧结产物破碎，与另一包含元素M的化合物混合均匀并在氧气气氛中进行第二次烧结，得到第二烧结产物；将所述第二烧产物进行破碎、筛分和分级，得到第二正极活性材料；可选地，所述烧结温度为600℃～900℃；所述烧结时间为5h～20h；S2: uniformly mixing a lithium source, a precursor of a second positive electrode active material and a compound containing element M and performing a first sintering in an oxygen atmosphere to obtain a first sintered product; crushing the first sintered product, uniformly mixing it with another compound containing element M and performing a second sintering in an oxygen atmosphere to obtain a second sintered product; crushing, screening and grading the second sintered product to obtain a second positive electrode active material; optionally, the sintering temperature is 600° C. to 900° C.; the sintering time is 5 h to 20 h;
    S3：将所述第一正极活性材料与所述第二正极活性材料混合，得到所述正极活性材料。S3: mixing the first positive electrode active material and the second positive electrode active material to obtain the positive electrode active material.
  16. 根据权利要求15所述的方法，其中在步骤S1和S2中，所述锂源选自碳酸锂、氢氧化锂和草酸锂中的至少一种。The method according to claim 15, wherein in steps S1 and S2, the lithium source is selected from at least one of lithium carbonate, lithium hydroxide and lithium oxalate.
  17. 根据权利要求15或16所述的方法，其中在步骤S1和S2中，所述第一正极活性材料的前驱体和所述第二正极活性材料的前驱体各自为Ni 1-x-yCo xMn y(OH) 2和Ni 1-x-yCo xMn yCO 3中的至少一种，其中0.01≤x≤0.1，0.01≤y≤0.1。 The method according to claim 15 or 16, wherein in steps S1 and S2, the precursor of the first cathode active material and the precursor of the second cathode active material are each at least one of Ni1 - xyCoxMny ( OH ) 2 and Ni1 - xyCoxMnyCO3 , wherein 0.01≤x≤0.1 , 0.01≤y≤0.1.
  18. 根据权利要求15至17中任一项所述的方法，其中在步骤S1和S2中，所述M选自Zr、Sr、Y、Sb、W、Ti、Mg、Nb、Hf、Mo、La、Na、B、Al、F和Ce中的一种或多种。The method according to any one of claims 15 to 17, wherein in steps S1 and S2, M is selected from one or more of Zr, Sr, Y, Sb, W, Ti, Mg, Nb, Hf, Mo, La, Na, B, Al, F and Ce.
  19. 根据权利要求15至18中任一项所述的方法，其中在步骤S1 和S2中，氧气气氛中氧气的浓度为80％以上，可选90％以上，还可选99.9％以上。The method according to any one of claims 15 to 18, wherein in steps S1 and S2, the concentration of oxygen in the oxygen atmosphere is above 80%, optionally above 90%, and further optionally above 99.9%.
  20. 一种二次电池，包括权利要求1-13中任一项所述的正极活性材料或通过权利要求14-19中任一项所述的方法制备的正极活性材料。A secondary battery comprising the positive electrode active material according to any one of claims 1 to 13 or the positive electrode active material prepared by the method according to any one of claims 14 to 19.
  21. 一种用电装置，包括权利要求20所述的二次电池。An electrical device comprising the secondary battery according to claim 20.
PCT/CN2022/127059 2022-10-24 2022-10-24 Positive electrode active material and preparation method therefor, positive electrode sheet, secondary battery and electric device WO2024086978A1 (en)

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CN112447968A (en) * 2019-09-02 2021-03-05 宁德时代新能源科技股份有限公司 Positive electrode active material, positive electrode plate and lithium ion secondary battery
CN112447964A (en) * 2019-09-02 2021-03-05 宁德时代新能源科技股份有限公司 Positive electrode active material, positive electrode plate and lithium ion secondary battery
CN115084508A (en) * 2022-08-23 2022-09-20 欣旺达电动汽车电池有限公司 Positive active material, battery and preparation method thereof

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CN111384372A (en) * 2018-12-29 2020-07-07 宁德时代新能源科技股份有限公司 High-compaction-density positive electrode material and electrochemical energy storage device
CN112447968A (en) * 2019-09-02 2021-03-05 宁德时代新能源科技股份有限公司 Positive electrode active material, positive electrode plate and lithium ion secondary battery
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