CN115881942A - Single-crystal type anode material and preparation method and application thereof - Google Patents
Single-crystal type anode material and preparation method and application thereof Download PDFInfo
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Abstract
The invention relates to the field of new energy materials, in particular to a single-crystal type anode material and a preparation method and application thereof. The chemical formula of the single crystal type anode material is LiNi x Co y Me 1‑x‑ y O 2 (ii) a Wherein x is more than or equal to 0, y is more than or equal to 0, x + y is more than 0 and less than or equal to 1, me comprises: at least one of metal elements such as Al, ti, mg, sr, W, ca, nb, cr, mn, fe, etc. The single crystal type anode material has accurate lithium content, intact layered structure, stable structure, excellent electrochemical performance, uniform distribution of internal element components, higher charge-discharge specific capacity and stable cycle performance.
Description
Technical Field
The invention relates to the field of new energy materials, in particular to a single-crystal type anode material and a preparation method and application thereof.
Background
Lithium ion batteries have the advantages of high energy density, high power density, long service life and the like, and play an increasingly important role in the fields of portable equipment, automobiles, energy storage and the like. In the traditional positive electrode material with spherical and other morphological structures, which is composed of primary particles, a large number of crystal boundaries exist in the particles of the positive electrode material, and lattice contraction or expansion exists in the charging or discharging process of the positive electrode material, so that the situation that the stress and the direction are inconsistent between the adjacent primary particles easily occurs, and obvious cracks occur between the primary particles. Therefore, due to the inherent multi-level structural morphology characteristics of the anode material, the problems of main body morphology damage, primary particle shedding, intercrystalline electrolyte infiltration, impurity phase formation and the like can easily occur after long circulation, so that the electrochemical performance of the anode material is rapidly attenuated.
In order to develop a high-performance and high-strength anode material, researchers propose to synthesize a micron-sized single crystal particle anode material. The single crystal anode material is widely applied to batteries due to excellent high-temperature performance, high-voltage performance, long cycle performance and stable structural morphology. Although there have been studies and techniques using CoCO 3 、Ni x Co y Mn 1-x-y (OH) 2 Precursor with equal specific morphology, tap density and specific surface area is used for preparing single crystal anode material by molten salt method, but the reaction time is generally longer, and the CoCO used in the reaction is reacted 3 、Ni x Co y Mn 1-x-y (OH) 2 The requirement of the precursor is severe, so that the production cost of the current single crystal cathode material is higher than that of the spherical cathode material produced by the conventional method, and the further expansion of the market share of the single crystal cathode material in the cathode material is hindered. In addition, researchers have proposed the use of solid phasesAccording to the mixing method, raw materials consisting of different elements are subjected to molten salt reaction to prepare the single crystal ternary electrode material, but the single crystal positive electrode material prepared by the method has nonuniform internal element components and segregation, and the performance of the positive electrode material battery is seriously influenced.
Currently, the strategy of synthesizing single crystal cathode materials at high cost still has difficulty in meeting the urgent need of new energy markets for high-performance single crystal cathode materials. Therefore, the targeted development of a high-efficiency, simple and low-cost synthesis method for preparing the micron-sized single-crystal large-particle electrode material has important significance for promoting the development of the commercial single-crystal positive electrode material.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
In one aspect, the invention relates to a single crystal type anode material, the chemical formula of which is LiNi x Co y Me 1-x-y O 2 ；
Wherein x is more than or equal to 0, y is more than or equal to 0, x + y is more than 0 and less than or equal to 1, me comprises: at least one of Al, ti, mg, sr, W, ca, nb, cr, mn or Fe.
The single crystal type anode material has accurate lithium content, intact layered structure, stable structure, excellent electrochemical performance, uniform distribution of internal element components, higher charge-discharge specific capacity and stable cycle performance.
In another aspect, the invention also relates to a preparation method of the single crystal type cathode material, which comprises the following steps:
(a) Adding a precipitator into the solution A containing soluble salt, and then carrying out coprecipitation reaction to obtain a nano particle precursor;
(b) Sintering, granulating and washing the mixed system of the nanoparticle precursor and the molten salt to obtain single crystal particles;
the sintering temperature is 850-1000 ℃; the sintering time is 1-5 h;
(c) Calcining the mixture of single crystal particles and lithium source;
the calcining temperature is 650-950 ℃; the calcining time is 3-10 h.
The preparation method of the single crystal type anode material is efficient, simple, convenient, low in cost and high in sintering granulation speed, trace doping elements can be flexibly introduced when the precursor is prepared, sintering and calcining processes are not required to be carried out under the protection of protective atmosphere, and the single crystal anode material with excellent electrochemical performance is obtained within very short reaction time.
The invention also relates to a positive pole piece which comprises the single-crystal positive pole material prepared by the preparation method of the single-crystal positive pole material.
In another aspect of the invention, the invention also relates to a lithium ion battery, which comprises the lithium ion battery.
Compared with the prior art, the invention has the following beneficial effects:
(1) The single crystal type anode material provided by the invention has the advantages of accurate lithium content, intact layered structure, stable structure, excellent electrochemical performance, uniform distribution of internal element components, higher charge-discharge specific capacity and stable cycle performance.
(2) The preparation method of the single crystal type anode material provided by the invention is efficient, simple and convenient, low in cost and high in sintering granulation speed, trace doping elements can be flexibly introduced when the precursor is prepared, the sintering and calcining processes are not required to be carried out under the protection of a protective atmosphere, and the single crystal anode material with excellent electrochemical performance can be obtained within a very short reaction time.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a FESEM view of a single-crystal type positive electrode material in example 1 of the present invention;
fig. 2 is an FESEM view of a single crystal type positive electrode material in example 2 of the present invention;
fig. 3 is an XRD pattern of a single crystal form cathode material in example 1 of the present invention;
fig. 4 is an XRD pattern of a single-crystal positive electrode material in example 2 of the present invention;
FIG. 5 is a graph of long cycle performance at 1C for a single crystal form of a positive electrode material in example 1 of the present invention;
fig. 6 is a graph of long cycle performance at 1C for a single crystal form of a positive electrode material in example 2 of the present invention.
Detailed Description
The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and the detailed description, but those skilled in the art will understand that the following described embodiments are some, not all, of the embodiments of the present invention, and are only used for illustrating the present invention, and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The examples, in which specific conditions are not specified, were carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are conventional products which are not indicated by manufacturers and are commercially available.
In one aspect, the invention relates to a single crystal type anode material, the chemical formula of which is LiNi x Co y Me 1-x-y O 2 ；
Where 0. Ltoreq. X, 0. Ltoreq. Y,0 < x + y. Ltoreq.1, me includes, but is not limited to: at least one element selected from Al, ti, mg, sr, W, ca, nb, cr, mn and Fe.
The single crystal type anode material has accurate lithium content, intact layered structure, stable structure, excellent electrochemical performance, uniform distribution of internal element components, higher charge-discharge specific capacity and stable cycle performance.
When the single crystal type positive electrode material is a nickel-based positive electrode material, the chemical formula can be, but is not limited to, liNiO 2 、LiNi 1/3 Co 1/3 Mn 1/3 O 2 、LiNi 0.4 Co 0.2 Mn 0.4 O 2 、LiNi 0.5 Co 0.2 Mn 0.3 O 2 、LiNi 0.6 Co 0.2 Mn 0.2 O 2 、LiNi 0.7 Co 0.1 Mn 0.2 O 2 、LiNi 0.8 Co 0.1 Mn 0.1 O 2 、LiNi 0.8 Mn 0.2 O 2 Or LiNi 0.9 Co 0.1 O 2 At least one of (a).
When the single crystal positive electrode material is a manganese-based positive electrode material, the chemical formula can be, but is not limited to, li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 Or LiNi 0.2 Co 0.2 Mn 0.6 O 2 At least one of (1).
When the single-crystal positive electrode material is a cobalt-based positive electrode material, the chemical formula of the single-crystal positive electrode material can be LiNi 0.1 Co 0.9 O 2 Or LiMn 0.1 Co 0.9 O 2 。
Preferably, the single crystal type positive electrode material further includes anions (BO) 3 3- 、F - 、Br - 、Cl - 、PO 4 3- Etc.) and/or cations (V) 3+ 、Ta 4+ 、Zr 4+ 、Ce 4+ 、Mo 6+ 、Y 3+ 、La 3+ Etc.) replacement, doping.
Preferably, the grain size of the single crystal type positive electrode material is 1 to 13 μm.
In some specific embodiments, the particle size of the single crystal type positive electrode material may be, for example, but not limited to, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, or 13 μm.
In another aspect, the invention also relates to a preparation method of the single crystal type cathode material, which comprises the following steps:
(a) Adding a precipitator into the solution A containing soluble salt, and then carrying out coprecipitation reaction to obtain a nano particle precursor;
(b) Sintering, granulating and washing the mixed system of the nanoparticle precursor and the molten salt to obtain single crystal particles;
the sintering temperature is 850-1000 ℃; the sintering time is 1-5 h;
(c) Calcining the mixture of single crystal particles and a lithium source;
the calcining temperature is 650-950 ℃; the calcining time is 3-10 h.
In some embodiments, the temperature of the sintering may be, for example, but not limited to, 850 ℃, 860 ℃, 870 ℃, 880 ℃, 890 ℃, 900 ℃, 910 ℃, 920 ℃, 930 ℃, 940 ℃, 950 ℃, 960 ℃, 970 ℃, 980 ℃, 990 ℃, or 1000 ℃.
In some embodiments, the sintering time may be, for example, but not limited to, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, or 5h.
In some embodiments, the temperature of the calcination may be, for example, but not limited to, 650 ℃, 660 ℃, 670 ℃, 680 ℃, 690 ℃, 700 ℃, 710 ℃, 720 ℃, 730 ℃, 740 ℃, 750 ℃, 760 ℃, 770 ℃, 780 ℃, 790 ℃, 800 ℃, 810 ℃, 820 ℃, 830 ℃, 840 ℃, 850 ℃, 860 ℃, 870 ℃, 880 ℃, 890 ℃, 900 ℃, 910 ℃, 920 ℃, 930 ℃, 940 ℃ or 950 ℃.
In some embodiments, the time of the calcination may be, for example, but not limited to, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h.
According to the preparation method of the single crystal type anode material, the micron-sized single crystal large-particle electrode material for the lithium ion battery is prepared by utilizing the rapid granulation reaction of the nano particle precursor in a molten salt environment. Although the prior art reports the use of CoCO 3 、Ni x Co y Mn 1-x-y (OH) 2 The precursor is used for preparing the single crystal cathode material by a molten salt method, but the reaction time is long, and CoCO used in the reaction is 3 、Ni x Co y Mn 1-x-y (OH) 2 The requirement of the precursor is high, so that the production cost is higher than that of the conventional spherical anode material, and the development of the single crystal anode material is hindered; and a plurality of oxides are used after being mixed in a solid phaseThe molten salt is used for preparing the single crystal anode material, and the obtained anode material has uneven internal components and serious segregation, so that the performance of the anode material battery is greatly influenced. The rapid preparation strategy provided by the invention can fully ensure the uniform distribution of the internal element components of the anode material and the rapid and simple preparation of the nanoparticle precursor, and can obtain the micron-sized large-particle single crystal anode material with excellent electrochemical performance in a very short reaction time, thereby having the effects of remarkably improving the production capacity and reducing the production cost.
The positive electrode material containing anions, cation replacement or doping conditions and the like can also be prepared by the method.
Preferably, the sintering, the granulating and the calcining are carried out in an air or oxygen atmosphere, no special protective atmosphere is needed, and the cost is low.
Preferably, the amount of the soluble salt contained in the solution a is configured according to a chemical formula of a target cathode material.
Soluble salt is weighed according to the designed stoichiometric ratio and dissolved in water to prepare the solution with the molar concentration of 0.1-10mol L -1 Solution A containing soluble salts of (1).
Adding excessive 10% molar precipitation agent into the solution A for preparing nano particle precursor with size not more than 800nm.
Preferably, the molar ratio of the molten salt to the transition metal ions in the nanoparticle precursor is > 1.2.
In some specific embodiments, the molar ratio of the molten salt to the transition metal ions in the nanoparticle precursor can be, for example, but not limited to, 1.2, 2.4, 3.6, 4.8, 5.6, 6.4, or 6.8.
Preferably, the molar ratio of the lithium salt in the molten salt to the transition metal ions in the nanoparticle precursor is > 0.7.
In some specific embodiments, the molar ratio of the lithium salt in the molten salt to the transition metal ion in the nanoparticle precursor may be, for example, but not limited to, 0.7, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, or 4.5.
Preferably, the temperature rise rate of the sintering is 2-10 ℃/min.
In some specific embodiments, the temperature ramp rate for the sintering can be, for example, but not limited to, 2 deg.C/min, 3 deg.C/min, 4 deg.C/min, 5 deg.C/min, 6 deg.C/min, 7 deg.C/min, 8 deg.C/min, 9 deg.C/min, or 10 deg.C/min.
Preferably, the heating rate of the calcination is 2 to 10 ℃/min.
In some specific embodiments, the temperature ramp rate of the calcination can be, for example, but not limited to, 2 deg.C/min, 3 deg.C/min, 4 deg.C/min, 5 deg.C/min, 6 deg.C/min, 7 deg.C/min, 8 deg.C/min, 9 deg.C/min, or 10 deg.C/min.
Preferably, the size of the nanoparticle precursor in the largest direction is less than or equal to 800nm.
In some specific embodiments, the nanoparticle precursor may have a dimension in the largest direction of, for example, but not limited to, 400nm, 230nm, 110nm, 470nm, 330nm, 170nm, or 280nm.
The size of the precursor of the nano particles in the maximum direction is controlled within a certain range, and if the size exceeds 800nm, the time required for generating single crystal particles by the precursor particles is greatly increased, so that the effect of quickly preparing the nano particles into large particles cannot be achieved; and the distribution of the metal elements is easy to segregate and shows uneven distribution.
The precursor particles used in the invention are less than 1 μm, no special morphology requirement exists, the particle size is small, and the diffusion of metal ions among the particles is easily promoted during the calcination of molten salt, so that the large single crystal particles can be formed by faster melt growth.
Preferably, the shape of the nanoparticle precursor includes, but is not limited to, a shuttle, a rice grain, a sphere, a rod, a needle, a plate, or a random particle.
Preferably, the soluble salts include: at least one of soluble nickel salt, soluble cobalt salt or soluble salt of metal element Me;
preferably, the soluble salt comprises at least one of a nitrate, sulphate or chloride salt.
Preferably, the molten salt comprises: at least one of lithium oxide, lithium carbonate, lithium sulfate, lithium nitrate, lithium acetate, lithium hydroxide, lithium oxalate, or lithium chloride.
Preferably, the molten salt may also be a molten salt formed by mixing one or more of sodium/potassium carbonate, nitrate, chloride and sulfate with lithium salt.
Preferably, the precipitation agent comprises: at least one of sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, sodium oxalate, ammonium oxalate, sodium hydroxide, potassium hydroxide, ammonia, sodium citrate, potassium citrate, or citric acid;
preferably, the lithium source includes: at least one of lithium hydroxide, lithium carbonate, lithium sulfate, lithium nitrate, lithium acetate, lithium oxalate, or lithium chloride.
The invention also relates to a positive pole piece, which comprises the single-crystal positive pole material or the single-crystal positive pole material prepared by the preparation method of the single-crystal positive pole material.
In another aspect of the invention, the invention also relates to a lithium ion battery, which comprises the lithium ion battery.
The lithium ion battery has excellent electrochemical performance.
Embodiments of the present invention will be described in detail below with reference to specific examples and comparative examples.
Example 1: rapid preparation of single crystal LiNi 0.6 Co 0.2 Mn 0.2 O 2 Positive electrode material
According to the weight percentage of nickel: cobalt: manganese =60:20: respectively weighing 30mmol of nickel acetate, 10mmol of cobalt acetate and 10mmol of manganese acetate according to the metal ion molar ratio of 20, dissolving the nickel acetate, the 10mmol of cobalt acetate and the 10mmol of manganese acetate in 75mL of deionized water to prepare a solution A, adding 100mmol of oxalic acid into the solution A, stirring and reacting for 30min, filtering and drying to obtain a nanoparticle precursor.
Mixing the nanoparticle precursor powder with a molten salt (the molar ratio of lithium carbonate to sodium sulfate is 1): 2.8 mixing and grinding, heating and sintering in air atmosphere at 6 deg.C for min -1 Heating to 920 ℃ at a speed, preserving heat for 2h, and then cooling to room temperature to obtain the mixture of single crystal particles and molten saltA compound (I) is provided. And then deionized water is used for washing the soluble lithium salt in the mixture to obtain single crystal particle powder, and the single crystal particle powder is placed in an oven for drying.
Mixing the dried single crystal particle powder with lithium hydroxide in a tube furnace (oxygen atmosphere) for calcining, carrying out heat preservation treatment again for 5 hours at 750 ℃, and then cooling to room temperature along with the furnace to obtain the single crystal LiNi with accurate lithium content and good laminated structure 0.6 Co 0.2 Mn 0.2 O 2 And (3) a positive electrode material.
Example 2: rapid preparation of single crystal Li 1.2 Ni 0.19 Mn 0.6 Sr 0.01 O 2 Positive electrode material
According to the proportion of nickel: manganese: strontium =19:60:1, respectively weighing 9.5mmol of nickel sulfate, 30mmol of manganese acetate and 0.5mmol of strontium nitrate according to the molar ratio of metal ions, dissolving the nickel sulfate, the manganese acetate and the strontium nitrate in 75mL of deionized water to prepare a solution A, adding 80mmol of sodium oxalate into the solution A, stirring for reaction for 30min, filtering and drying to obtain a nanoparticle precursor.
Mixing the nanoparticle precursor powder with a molten salt (the molar ratio of lithium carbonate to sodium sulfate is 1): 2.9 mixing and grinding, heating and sintering in air atmosphere at 6 deg.C for min -1 The temperature is increased to 950 ℃ at a speed and is kept for 2h, and then the mixture is cooled to room temperature to obtain the mixture of the single crystal particles and the molten salt. And then deionized water is used for washing the soluble lithium salt in the mixture to obtain single crystal particle powder, and the single crystal particle powder is placed in an oven for drying.
Mixing the dried single crystal particle powder with lithium hydroxide, calcining in a tubular furnace (oxygen atmosphere), preserving heat for 5 hours at 850 ℃, and then cooling to room temperature along with the furnace to obtain the single crystal Li with accurate lithium content and good laminated structure 1.2 Ni 0.19 Mn 0.6 Sr 0.01 O 2 And (3) a positive electrode material.
Example 3: rapid preparation of single crystal LiNi 0.75 Co 0.24 Al 0.01 O 2 Positive electrode material
According to the proportion of nickel: manganese: aluminum =75:24:1, respectively weighing 32.5mmol of nickel sulfate, 12mmol of cobalt acetate and 0.5mmol of aluminum acetylacetonate, dissolving the nickel sulfate, the cobalt acetate and the aluminum acetylacetonate in 60mL of deionized water to prepare a solution A, adding 80mmol of sodium carbonate into the solution A, stirring for reaction for 30min, filtering and drying to obtain a nanoparticle precursor.
Mixing the nanoparticle precursor powder with a molten salt (the molar ratio of lithium nitrate to sodium chloride is 1:2.7 mixing and grinding, heating and sintering in air atmosphere at 5 deg.C for min -1 The temperature is raised to 910 ℃ at a speed and is preserved for 2h, and then the mixture of the single crystal particles and the molten salt is obtained after the mixture is cooled to room temperature. And then deionized water is used for washing the soluble lithium salt in the mixture to obtain single crystal particle powder, and the single crystal particle powder is placed in an oven for drying.
Mixing the dried single crystal particle powder with lithium hydroxide, calcining in a tube furnace (oxygen atmosphere), preserving heat for 5 hours at 740 ℃, and then cooling to room temperature along with the furnace to obtain the single crystal LiNi with accurate lithium content and good laminated structure 0.75 Co 0.24 Al 0.01 O 2 And (3) a positive electrode material.
Example 4: rapid preparation of single crystal LiNi 0.90 Mn 0.0.09 Mg 0.01 O 2 Positive electrode material
According to the proportion of nickel: manganese: magnesium =90:9:1, respectively weighing 45mmol of nickel nitrate, 4.5mmol of manganese nitrate and 0.5mmol of magnesium nitrate, dissolving the nickel nitrate, the manganese nitrate and the magnesium nitrate in 70mL of deionized water to prepare a solution A, adding 140mmol of sodium hydroxide into the solution A, stirring for reaction for 30min, filtering and drying to obtain a nanoparticle precursor.
Mixing the nanoparticle precursor powder and a molten salt (the molar ratio of lithium acetate to sodium nitrate is 1:2.8 mixing and grinding, heating and sintering in air atmosphere at 5 deg.C for min -1 The temperature is increased to 890 ℃ at a speed and is kept for 2h, and then the mixture is cooled to room temperature to obtain the mixture of the single crystal particles and the molten salt. And then deionized water is used for washing the soluble lithium salt in the mixture to obtain single crystal particle powder, and the single crystal particle powder is placed in an oven for drying.
Mixing the dried single crystal particle powder with lithium hydroxide, calcining in a tubular furnace (oxygen atmosphere), preserving heat for 4 hours again at 650 ℃, and then cooling to room temperature along with the furnace to obtain the single crystal particle powder with accurate lithium content and complete laminated structureGood single crystal LiNi 0.90 Mn 0.0.09 Mg 0.01 O 2 And (3) a positive electrode material.
Example 5: rapid preparation of single crystal LiNi 0.16 Co 0.10 Mn 0.54 O 2 Positive electrode material
According to the proportion of nickel: cobalt: manganese =16:10: respectively weighing 8mmol of nickel chloride, 5mmol of cobalt nitrate and 27mmol of manganese chloride according to the molar ratio of the metal ions of 54, dissolving the nickel chloride, the 5mmol of cobalt nitrate and the 27mmol of manganese chloride in 60mL of deionized water to prepare a solution A, adding 140mmol of sodium citrate into the solution A, stirring and reacting for 30min, filtering and drying to obtain the nanoparticle precursor.
Mixing the nanoparticle precursor powder and molten salt (the molar ratio of lithium acetate to sodium chloride is 1:2.9 mixing and grinding, heating and sintering in air atmosphere at 8 deg.C for min -1 The temperature is increased to 960 ℃ at a speed and is kept for 3h, and then the mixture is cooled to room temperature to obtain the mixture of the single crystal particles and the molten salt. And then deionized water is used for washing the soluble lithium salt in the mixture to obtain single crystal particle powder, and the single crystal particle powder is placed in an oven for drying.
Mixing the dried single crystal particle powder with lithium carbonate, calcining in air atmosphere, preserving heat for 5 hours again at 850 ℃, and then cooling to room temperature along with the furnace to obtain the single crystal LiNi with accurate lithium content and good laminated structure 0.16 Co 0.1 Mn 0.54 O 2 And (3) a positive electrode material.
Example 6: rapid preparation of single crystal LiNi 0.33 Co 0.33 Mn 0.33 O 2 Positive electrode material
According to the proportion of nickel: cobalt: manganese =16.5:16.5: respectively weighing 16.5mmol of nickel chloride, 16.5mmol of cobalt chloride and 16.5mmol of manganese nitrate according to the molar ratio of metal ions of 16.5, dissolving the nickel chloride, the cobalt chloride and the manganese nitrate in 60mL of deionized water to prepare a solution A, adding 140mmol of sodium citrate into the solution A, stirring for reaction for 30min, filtering and drying to obtain the nanoparticle precursor.
Mixing the nanoparticle precursor powder with a molten salt (the molar ratio of lithium nitrate to potassium sulfate is 1:3.0 mixing and grinding, heating and sintering in air atmosphere at 8 deg.C for min -1 The temperature is increased to 970 ℃ at a speed and is preserved for 3 hoursAnd then cooling to room temperature to obtain a mixture of single crystal particles and molten salt. And then deionized water is used for washing the soluble lithium salt in the mixture to obtain single crystal particle powder, and the single crystal particle powder is placed in an oven for drying.
Mixing the dried single crystal particle powder with lithium carbonate, calcining in air atmosphere, preserving heat for 5 hours at 960 ℃, and then cooling to room temperature along with the furnace to obtain the single crystal LiNi with accurate lithium content and good laminated structure 0.33 Co 0.33 Mn 0.33 O 2 And (3) a positive electrode material.
Example 7: rapid preparation of single crystal LiNi 0.02 Co 0.96 Mn 0.02 O 2 Positive electrode material
According to the proportion of nickel: cobalt: manganese =0.2:96: respectively weighing 0.1mmol of nickel chloride, 43mmol of cobalt chloride and 0.1mmol of manganese nitrate according to the metal ion molar ratio of 0.2, dissolving the nickel chloride, the cobalt chloride and the manganese nitrate in 60mL of deionized water to prepare a solution A, adding 140mmol of citric acid into the solution A, stirring for reaction for 30min, filtering and drying to obtain the nanoparticle precursor.
Mixing the nanoparticle precursor powder with a molten salt (the molar ratio of lithium sulfate to lithium hydroxide is 1:2.4 mixing and grinding, heating and sintering in air atmosphere at 8 deg.C for min -1 The temperature is raised to 1000 ℃ at a speed and kept for 2h, and then the mixture of the single crystal particles and the molten salt is obtained after cooling to room temperature. And then deionized water is used for washing the soluble lithium salt in the mixture to obtain single crystal particle powder, and the single crystal particle powder is placed in an oven for drying.
Mixing the dried single crystal particle powder with lithium carbonate, calcining in air atmosphere, preserving heat for 5 hours at 1000 ℃, and then cooling to room temperature along with the furnace to obtain the single crystal LiNi with accurate lithium content and good laminated structure 0.05 Co 0.9 Mn 0.05 O 2 And (3) a positive electrode material.
Examples of the experiments
FIG. 1 is a single crystal form LiNi in example 1 of the present invention 0.6 Co 0.2 Mn 0.2 O 2 FESEM image of positive electrode material. LiNi is evident from the figure 0.6 Co 0.2 Mn 0.2 O 2 The particles of the positive electrode material are in micron-scale sizeThe surface of the particle is smooth, belonging to single crystal particles.
FIG. 2 shows a single crystal form Li in example 2 of the present invention 1.2 Ni 0.19 Mn 0.6 Sr 0.01 O 2 FESEM image of positive electrode material. It can be seen that Li 1.2 Ni 0.19 Mn 0.6 Sr 0.01 O 2 The particles of the anode material are micron-sized single crystal large particles, and the surfaces of the particles are smooth.
FIG. 3 is a single crystal form LiNi in example 1 of the present invention 0.6 Co 0.2 Mn 0.2 O 2 XRD pattern of the positive electrode material. alpha-NaFeO with diffraction peak and layered structure 2 The two pairs of diffraction peaks of (006)/(012) and (018)/(110) are matched and are obvious in splitting, which shows that the lithium-doped calcined single-crystal LiNi 0.6 Co 0.2 Mn 0.2 O 2 The positive electrode material has a good layered structure.
FIG. 4 shows a single crystal form Li in example 2 of the present invention 1.2 Ni 0.19 Mn 0.6 Sr 0.01 O 2 XRD pattern of the positive electrode material. alpha-NaFeO with diffraction peak and laminated structure 2 Match, observed in the range of 20-25 ℃ attributable to Li 2 MnO 3 The diffraction peaks of (006)/(012) and (018)/(110) are clearly separated, indicating that the calcination with additional lithium ion addition resulted in single crystalline form Li with good layered structure 1.2 Ni 0.19 Mn 0.6 Sr 0.01 O 2 And (3) a positive electrode material.
The single crystal type positive electrode materials of examples 1 and 2 were mixed with conductive carbon black and a polyvinylidene fluoride binder at a ratio of 90:5:5 in an organic solvent for mixing, then coating the slurry on an aluminum foil substrate, drying and rolling the aluminum foil substrate, and cutting the aluminum foil substrate into an electrode wafer with the diameter of 1.0cm to be used as a positive plate. And assembling the positive plate, the diaphragm and the lithium plate into a button cell in a closed glove box, and testing the cell performance on an electrochemical tester.
FIG. 5 shows LiNi, a single crystal, in example 1 of the present invention 0.6 Co 0.2 Mn 0.2 O 2 Cycle performance diagram of the cathode material at 1C current density. As can be seen from the figure, single-crystal LiNi 0.6 Co 0.2 Mn 0.2 O 2 The anode material has excellent long-cycle stability in the voltage range of 2.8-4.3V and the current density of 1C, and the first discharge capacity of the anode material reaches 160.9mAh g -1 The capacity is kept at 137.7mAh g after 200 cycles -1 And the capacity retention rate of 85.6 percent is achieved.
FIG. 6 Single Crystal Li in example 2 of the present invention 1.2 Ni 0.19 Mn 0.6 Sr 0.01 O 2 Cycle performance of the positive electrode material at 1C current density. The first discharge capacity of the single crystal anode material is 220.4mAh g in the voltage range of 2.8-4.8V and under the current density of 1C -1 The capacity after 200 cycles of circulation reaches 207.5mAh g -1 The corresponding capacity retention was as high as 94.1%, showing excellent long cycle performance.
Tests show that the positive electrode materials prepared in other embodiments are micron-sized single crystal large particles in morphology, and have high charge-discharge specific capacity and cycling stability.
While particular embodiments of the present invention have been illustrated and described, it will be appreciated that the above embodiments are merely illustrative of the technical solution of the present invention and are not restrictive; those of ordinary skill in the art will understand that: modifications may be made to the teachings of the foregoing embodiments without departing from the spirit or scope of the present invention, or equivalents may be substituted for some or all of the features thereof; the modifications or the substitutions do not cause the essence of the corresponding technical solutions to depart from the scope of the technical solutions of the embodiments of the present invention; it is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
Claims (10)
1. A single crystal type anode material is characterized in that the chemical formula of the single crystal type anode material is LiNi x Co y Me 1-x- y O 2 ；
Wherein x is more than or equal to 0, y is more than or equal to 0, x + y is more than 0 and less than or equal to 1, me comprises: at least one of Al, ti, mg, sr, W, ca, nb, cr, mn or Fe.
2. The single crystal-type positive electrode material according to claim 1, wherein the particle diameter of the single crystal-type positive electrode material is 1 to 13 μm.
3. The method for producing a single-crystal type positive electrode material according to claim 1 or 2, comprising the steps of:
(a) Adding a precipitator into the solution A containing soluble salt, and then carrying out coprecipitation reaction to obtain a nano particle precursor;
(b) Sintering, granulating and washing the mixed system of the nanoparticle precursor and the molten salt to obtain single crystal particles;
the sintering temperature is 850-1000 ℃; the sintering time is 1-5 h;
(c) Calcining the mixture of single crystal particles and lithium source;
the calcining temperature is 650-950 ℃; the calcining time is 3-10 h.
4. The method for producing a single-crystal positive electrode material according to claim 3, wherein the molar ratio of the molten salt to the transition metal ions in the nanoparticle precursor is > 1.2;
preferably, the molar ratio of lithium salt in the molten salt to transition metal ions in the nanoparticle precursor is > 0.7.
5. The method for producing a single-crystal positive electrode material according to claim 3, wherein the temperature increase rate of the sintering is 2 to 10 ℃/min;
preferably, the heating rate of the calcination is 2 to 10 ℃/min.
6. The method of claim 3, wherein the nanoparticle precursor has a size of 800nm or less in the maximum direction.
7. The method of preparing a single crystal-type positive electrode material according to claim 3, wherein the soluble salt comprises: at least one of soluble nickel salt, soluble cobalt salt or soluble salt of metal element Me;
preferably, the soluble salt comprises at least one of a nitrate, sulfate or chloride salt.
8. The method for producing a single-crystal positive electrode material according to claim 3, wherein the molten salt comprises: at least one of lithium oxide, lithium carbonate, lithium sulfate, lithium nitrate, lithium acetate, lithium hydroxide, lithium oxalate, or lithium chloride;
preferably, the precipitation agent comprises: at least one of sodium carbonate, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, sodium oxalate, ammonium oxalate, sodium hydroxide, potassium hydroxide, ammonia, sodium citrate, potassium citrate, or citric acid;
preferably, the lithium source includes: at least one of lithium hydroxide, lithium carbonate, lithium sulfate, lithium nitrate, lithium acetate, lithium oxalate or lithium chloride.
9. A positive electrode plate, characterized by comprising the single crystal type positive electrode material of claim 1 or 2 or the single crystal type positive electrode material prepared by the method for preparing the single crystal type positive electrode material of any one of claims 3 to 8.
10. A lithium ion battery comprising the lithium ion battery of claim 9.
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| CN117525333A (en) * | 2023-11-16 | 2024-02-06 | 南开大学 | Titanium molten salt-assisted cladding doped monocrystal cobalt-free lithium nickel oxide positive electrode material, and preparation method and application thereof |
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| CN117525333A (en) * | 2023-11-16 | 2024-02-06 | 南开大学 | Titanium molten salt-assisted cladding doped monocrystal cobalt-free lithium nickel oxide positive electrode material, and preparation method and application thereof |
| CN117525333B (en) * | 2023-11-16 | 2024-05-28 | 南开大学 | Titanium molten salt-assisted cladding doped monocrystal cobalt-free lithium nickel oxide positive electrode material, and preparation method and application thereof |
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