CN113889620A - Lithium ion secondary battery - Google Patents

Lithium ion secondary battery Download PDF

Info

Publication number
CN113889620A
CN113889620A CN202111095586.0A CN202111095586A CN113889620A CN 113889620 A CN113889620 A CN 113889620A CN 202111095586 A CN202111095586 A CN 202111095586A CN 113889620 A CN113889620 A CN 113889620A
Authority
CN
China
Prior art keywords
active material
positive
electrode active
lithium ion
secondary battery
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202111095586.0A
Other languages
Chinese (zh)
Inventor
马建军
沈睿
何立兵
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Contemporary Amperex Technology Co Ltd
Original Assignee
Contemporary Amperex Technology Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Contemporary Amperex Technology Co Ltd filed Critical Contemporary Amperex Technology Co Ltd
Priority to CN202111095586.0A priority Critical patent/CN113889620A/en
Publication of CN113889620A publication Critical patent/CN113889620A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2220/00—Batteries for particular applications
    • H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention discloses a lithium ion secondary battery. The lithium ion secondary battery comprises a positive pole piece, a negative pole piece, an isolating membrane and electrolyte; the positive pole piece comprises a positive current collector and a positive active material coating, wherein the positive active material coating contains Li with a general formulaxNiaCobMcO2Wherein M is selected from Mn and Al0.95 is less than or equal to 1.2, a is more than 0 and less than 1, b is more than 0 and less than 1, c is more than 0 and less than 1, and a + b + c is 1; the negative pole piece comprises a negative pole current collector and a negative pole active material coating, the negative pole active material coating comprises a graphitized carbon material with the graphitization degree of 92% -97% as a negative pole active material, and the compaction density of the negative pole active material coating is 1.5-1.8g/cm3. The lithium ion secondary battery has good electrical property and dynamic property.

Description

Lithium ion secondary battery
The application is a divisional application of a Chinese patent application No. 201711012117.1 filed on 26.10.2017.
Technical Field
The present invention relates to a lithium ion secondary battery having high energy density, and more particularly, to a lithium ion secondary battery having high energy density.
Background
With the increasing popularity of electric vehicles, the requirements on batteries are more and more strict. It is required that the battery have both high capacity and good cycle stability. For this reason, the skilled person has made various efforts from various aspects of positive and negative electrode active materials, additives, electrolytes, and the like of batteries.
For battery positive electrode active materials, NCM ternary materials have higher gram capacities and compacted densities than lithium iron phosphate. Therefore, the cell using the ternary material has a higher energy density. As for the negative electrode material, the graphite material has the advantages of good charge-discharge voltage platform, good matching with the positive electrode material, high average output voltage of the formed battery and the like, and is an electrode material with excellent performance. The specific capacity of the graphite material can be effectively improved by improving the lattice order degree (graphitization degree) of the graphite material. However, the high-capacity graphite is soft in texture, and is easy to deform after being pressed in the processing process of the pole piece, so that the infiltration of electrolyte is influenced, and the cycle performance and the rate performance of the battery are further influenced.
In view of the above, it is necessary to provide a lithium ion secondary battery having both high capacity and good electrical properties.
Disclosure of Invention
One object of the present invention is: a lithium ion secondary battery having both a high capacity and good electrochemical performance is provided.
The inventors have unexpectedly found, through extensive experiments, that a combination of a positive active material and a negative active material for a specific type of battery can improve the cycle life of a lithium ion secondary battery while increasing the cell energy density.
Specifically, the invention provides a lithium ion secondary battery, which comprises a positive pole piece, a negative pole piece, an isolating membrane and electrolyte;
the positive pole piece comprises a positive current collector and a positive active material coating, wherein the positive active material coating contains Li with a general formulaxNiaCobMcO2Wherein M is at least one selected from Mn and Al, x is 0.95-1.2, a is more than 0 and less than 1, b is more than 0 and less than 1, c is more than 0 and less than 1, and a + b + c is 1;
the negative pole piece comprises a negative pole current collector and a negative pole active material coating, wherein the negative pole active material coating comprises a graphitized carbon material with the graphitization degree of 92% -97% as a negative pole active material, and the compaction density of the negative pole active material coating is 1.50-1.80g/cm3。
Compared with the prior art, the lithium ion secondary battery provided by the invention has the advantages of high capacity and long cycle life by adopting specific positive and negative electrode active materials.
The invention also relates to a preparation method of the lithium ion secondary battery, which comprises the following steps:
1) using a compound of the formula LixNiaCobMcO2The positive active material is used for preparing the positive plate, wherein M is selected from at least one of Mn and Al, x is more than or equal to 0.95 and less than or equal to 1.2, a is more than 0 and less than 1, b is more than 0 and less than 1, c is more than 0 and less than 1, and a + b + c is equal to 1;
2) the graphitized carbon material with the graphitization degree of 92-97% is used as the negative active material to prepare the negative active material coating with the compaction density of 1.50-1.80g/cm3The negative electrode sheet of (1);
3) assembling the positive plate prepared in the step 1) and the negative plate prepared in the step 2) into a battery.
Detailed Description
The invention provides a lithium ion secondary battery, which comprises a positive pole piece, a negative pole piece, an isolating membrane and electrolyte;
wherein the positive pole piece comprises a positive current collector and a positive electrodeA positive electrode active material coating layer containing a positive electrode active material having a general formula of LixNiaCobMcO2Wherein M is at least one selected from Mn and Al, x is 0.95-1.2, a is more than 0 and less than 1, b is more than 0 and less than 1, c is more than 0 and less than 1, and a + b + c is 1;
the negative pole piece comprises a negative pole current collector and a negative pole active material coating, wherein the negative pole active material coating comprises a graphitized carbon material with the graphitization degree of 92% -97% as a negative pole active material, and the compaction density of the negative pole active material coating is 1.50-1.80g/cm3；
The inventors believe that a carbon material having a graphitization degree of 92% to 97% is used and the compacted density of the negative active material coating is controlled to 1.50 to 1.80g/cm3More gap structures can be formed in the pole pieces, and the cycling performance of the battery cell can be improved while the energy density of the battery cell is ensured. The inventor finds that when the graphitization degree is lower than 92%, the compaction density of the negative active material coating on the pole piece reaches 1.70g/cm3The pressure of the cold pressing roller needs to be increased, so that the graphite particle structure is damaged, the side reaction of the material is increased in the circulating process, and the circulating life is influenced. In addition, when the graphitization degree is low, the rebound of the pole piece is large, so that the practical use compaction is low, and the energy density of the battery cell is influenced. When the graphitization degree is higher than 97%, the compaction density of the negative active material coating on the pole piece reaches 1.70g/cm3Because the high graphitization degree graphite is soft in texture, the high graphitization degree graphite is easy to deform after being pressed, so that the pores among the particles in the pole piece are reduced, the infiltration of electrolyte is influenced, the local polarization of the battery core is increased, and the cycle performance and the multiplying power performance of the battery are further influenced. However, the above explanation is provided only for the convenience of those skilled in the art to understand the principle of the present invention, and it is not to be construed as limiting the present invention; the invention does not exclude the possibility of other different theoretical explanations of the principles of the invention as technology develops.
The inventors have further found that when the degree of graphitization of the graphite negative electrode material is more than 97%, it results in that the interlayer distance of the graphite material becomes small. In the charging and discharging processes, the volume change caused by the intercalation and deintercalation of lithium ions is large, which affects the stability of an SEI layer (when a battery is charged for the first time, a passivation layer formed on the surface of a negative electrode, namely a solid electrolyte interface film, due to the reaction of an electrolyte and a negative electrode material on a solid-liquid interphase layer), thereby causing the deterioration of the cycle performance; when the graphitization degree of the graphite cathode material is less than 92%, the crystallinity of graphite is low, the number of lattice defects is large, and side reactions are easy to occur in the circulation process to cause capacity fading. After a large number of experiments, the cathode material has been found to have a suitable degree of graphitization of 92% to 97%, preferably 93% to 95%.
The inventor further found that when the compacted density of the negative active material coating on the pole piece is less than 1.50g/cm3In the process, the contact between graphite particles is poor, the consistency of the current density of the pole piece is influenced, and the polarization of the battery cell is increased. In addition, too small a compaction density of the negative active material coating will affect the cell energy density, resulting in a lower cell energy density. When the compacted density of the negative active material coating on the pole piece is more than 1.80g/cm3In the process, the pores among the particles in the pole piece are reduced, and the particle structure is damaged by extrusion. Electrolyte infiltration is difficult, polarization is increased, and long-term cycle performance of the battery core is deteriorated. Therefore, the compacted density of the coating of the negative active material on the negative pole piece is 1.50-1.80g/cm3Preferably 1.60 to 1.70g/cm3。
In order to further improve the dynamic performance (especially the rate performance of a battery), the surface of the graphite negative electrode material can also be provided with a coating layer. The coating layer is typically amorphous carbon, for example at least one selected from carbon black, coke, soft carbon, hard carbon. The content of the amorphous carbon is generally 2 to 13%, preferably 2 to 10%, relative to the total weight of the electrode material. In some embodiments, the amorphous carbon is obtained by (high temperature) carbonizing at least one material selected from coal pitch, petroleum pitch, mesophase pitch, epoxy resin, phenol resin, furfural resin, urea resin, polyvinyl alcohol, polyvinyl chloride, polyethylene glycol, polyethylene oxide, polyvinylidene fluoride, acrylic resin, and polyacrylonitrile.
The lithium ion secondary battery of the present invention can be prepared by a method known in the art using the above-specified positive electrode material and negative electrode material. As described in detail below.
1. Preparing a positive plate:
generally, a positive electrode active material, a conductive agent, a binder and the like are mixed according to a certain weight ratio, a solvent is added, and the mixture is uniformly stirred under the action of a vacuum stirrer to obtain positive electrode slurry; uniformly coating the positive electrode slurry on a positive electrode current collector (such as an aluminum foil); and transferring the positive current collector coated with the positive slurry to an oven for drying, and then carrying out cold pressing and slitting to obtain the positive pole piece.
The positive electrode active material used in the present invention is LixNiaCobMcO2Wherein M is selected from at least one of Mn and Al, x is more than or equal to 0.95 and less than or equal to 1.2, a is more than 0 and less than 1, b is more than 0 and less than 1, c is more than 0 and less than 1, and a + b + c is equal to 1. This is a common ternary positive electrode material for lithium batteries in the art. When M is Mn, the ternary material is called NCM for short; when M is Al, the ternary material is called NCA for short. Both NCM and NCA ternary materials are known to have higher energy densities than lithium iron phosphate and are common battery materials in the art and are commercially available from a number of suppliers.
Specifically, the positive active material may be selected from LiNi0.33Co0.33Mn0.33O2、LiNi0.5Co0.2Mn0.3O2、LiNi0.5Co0.25Mn0.25O2、LiNi0.6Co0.2Mn0.2O2、LiNi0.8Co0.1Mn0.1O2、LiNi0.85Co0.1Mn0.05O2、LiNi0.8Co0.15Al0.05O2At least one of (1).
In a preferred embodiment of the present invention, the weight of the positive electrode active material accounts for 92 to 98% of the positive electrode active material coating layer.
In some embodiments of the present invention, the positive electrode active material may also be doped with at least one element selected from Al, Zr, Ti, B, Mg, V, Cr, F in order to further improve the battery performance.
In some embodiments of the present invention, the battery performance may be further improved by forming a coating layer on the surface of the positive electrode active material, and the coating layer compound may contain at least one of Al, Zr, Ti, and B elements, for example.
2. Preparing a negative plate:
1) preparation of negative electrode Material
In the present invention, the "graphitized carbon material" has a meaning generally understood by those skilled in the art, i.e., a carbon material having a graphite sheet-like structure mainly inside, which is suitable as a battery negative electrode material. The graphitized carbon material may be natural graphite, artificial graphite, or a mixture of both. The graphitized carbon material having a graphitization degree of 92% to 97% used in the present invention can be prepared, for example, by the following method:
(1) crushing the petroleum-series forged needle coke or the coal-series forged needle coke to obtain a raw material with the average particle size of 5-20 mu m;
(2) shaping the raw material in the step (1), and then carrying out classification treatment so as to adjust the particle size distribution of the raw material (preferably, removing large particles with the particle size larger than Dv90 and small particles with the particle size smaller than Dv 10);
(3) performing high-temperature graphitization treatment on the raw material subjected to shaping and screening in the step (2), for example, in an Acheson graphitization furnace at the temperature of 2800-;
(4) and (4) screening and demagnetizing the material obtained in the step (3) to obtain the required negative electrode material.
The shaping treatment in step (2) is a common treatment method in the preparation process of the artificial graphite, and is well known to those skilled in the art, and can be performed by using any shaping machine or other shaping equipment commonly used in the art. The classification treatment in the step (2) can be carried out using a classifying screen (sieving method), a gravity classifier, a centrifugal separator, or the like which is generally used in the art. Optionally, after step (3) and before step (4), a coating carbonization step may be performed, that is, the product obtained in step (3) is mixed with at least one material selected from coal tar pitch, petroleum pitch, mesophase pitch, epoxy resin, phenol resin, furfural resin, urea resin, polyvinyl alcohol, polyvinyl chloride, polyethylene glycol, polyethylene oxide, polyvinylidene fluoride, acrylic resin, and polyacrylonitrile, and subjected to a high temperature carbonization treatment. The temperature of the carbonization treatment is, for example, 900-1500 ℃, such as 1000-1400 ℃ or 1100-1300 ℃.
Alternatively, natural graphite or commercially available graphitized carbon materials having a graphitization degree of 92% to 97% may be used as they are.
The degree of graphitization of the graphitized carbon material can be measured by a method known in the art, for example, by an X-ray diffractometer (see, for example, chong liang et al, "XRD measurement of degree of graphitization of carbon material", volume 32, 3 rd of university of south and central industries, 6 months 2001).
2) Assembling of negative electrode sheet
Mixing a negative electrode active material, a thickening agent, a binder and the like according to a certain weight, adding a solvent (such as deionized water), and obtaining stable negative electrode slurry under the action of a vacuum stirrer; uniformly coating the negative electrode slurry on a negative electrode current collector (such as copper foil); and transferring the negative current collector coated with the negative slurry to an oven for drying, and then carrying out cold pressing and slitting to obtain a negative pole piece.
In the preparation method, the compaction density of the negative active material coating obtained in the pole piece rolling process can be controlled by adjusting the rolling pressure or the roll gap clearance of cold pressing equipment in the cold pressing process.
In a preferred embodiment of the present invention, the weight of the negative active material accounts for 92% to 98% of the negative active material coating layer.
3. Preparing electrolyte:
as the nonaqueous electrolytic solution, a lithium salt solution dissolved in an organic solvent is generally used. The lithium salt is, for example, LiClO4、LiPF6、LiBF4、LiAsF6、LiSbF6Etc. inorganic lithium salt, or LiCF3SO3、LiCF3CO2、Li2C2F4(SO3)2、LiN(CF3SO2)2、LiC(CF3SO2)3、LiCnF2n+1SO3(n is more than or equal to 2) and the like. Used in nonaqueous electrolyte solution areExamples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate, chain carbonates such as dimethyl carbonate, diethyl carbonate, and methylethyl carbonate, chain esters such as methyl propionate, chain esters such as γ -butyrolactone, chain ethers such as dimethoxyethane, diethyl ether, diglyme, and triglyme, cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, nitriles such as acetonitrile and propionitrile, and mixtures of these solvents.
For example, Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC), diethyl carbonate (DEC) are mixed at a certain volume ratio, and then a well-dried lithium salt LiPF is added6Dissolving in mixed organic solvent to obtain electrolyte.
4. And (3) isolation film:
the isolating film has no special requirement and can be selected according to actual requirements, and specifically, the isolating film can be selected from polyethylene films, polypropylene films, polyvinylidene fluoride films and multilayer composite films thereof.
5. Preparing a full battery:
stacking the positive pole piece, the isolating film and the negative pole piece in sequence to enable the isolating film to be positioned between the positive pole piece and the negative pole piece to play an isolating role, and then winding to obtain a bare cell; placing the bare cell in an outer packaging shell, injecting the prepared electrolyte into the dried bare cell, and performing vacuum packaging, standing, formation, shaping and other processes to obtain the lithium ion battery.
In order to make the objects, technical solutions and advantageous technical effects of the present invention more clear, the present invention is further described in detail below with reference to examples. However, it should be understood that the embodiments of the present invention are only for explaining the present invention and are not for limiting the present invention, and the embodiments of the present invention are not limited to the embodiments given in the specification. The examples were prepared under the conventional conditions, or under the conditions recommended by the material supplier, without specifying the experimental conditions.
Examples
Example 1
The battery of example 1 was prepared as follows.
1. Preparing a positive pole piece: reacting LiNi0.6Co0.2Mn0.2O2SuperP (conductive agent), PVDF (binder) according to a mass ratio of 97: 1: 2, mixing, adding a solvent, and uniformly stirring under the action of a vacuum stirrer to obtain anode slurry; uniformly coating the positive electrode slurry on a positive electrode current collector aluminum foil; and transferring the positive electrode plate to an oven for drying, and then carrying out cold pressing to obtain the positive electrode plate.
2. Preparing a negative pole piece: a sample of an artificial graphite negative electrode active material having a graphitization degree of 94% was taken (measured by an X-ray diffractometer). Mixing an artificial graphite negative electrode active material, sodium carboxymethylcellulose (a thickening agent) and SBR (styrene butadiene rubber binder) according to a mass ratio of 97: 1.2: 1.8, mixing, adding deionized water, and obtaining uniform cathode slurry under the action of a vacuum stirrer; uniformly coating the negative electrode slurry on a copper foil of a negative electrode current collector; transferring the mixture to an oven for drying, and then performing cold pressing to obtain the cathode active material coating with the compacted density of 1.5g/cm3The negative electrode plate of (1).
The compacted density here is determined by the following method: and (3) tabletting the coated pole piece on a roller press, adjusting the rolling pressure or the gap between rollers, and testing the thickness of the rolled pole piece.
The compaction density (weight of pole piece per unit area-weight of current collector per unit area)/(thickness of single face of pole piece-thickness of current collector)
3. Preparing electrolyte: ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC), diethyl carbonate (DEC) were mixed in a volume ratio of 3:6:1, and then a well-dried lithium salt LiPF6Dissolving the electrolyte into a mixed organic solvent according to the proportion of 1mol/L to prepare the electrolyte.
4. And (3) isolation film: 12-micron PP/PE composite isolating membrane
5. Preparing a full battery: stacking the positive plate, the isolating film and the negative plate in sequence to enable the isolating film to be positioned between the positive plate and the negative plate to play an isolating role, and then winding to obtain a bare cell; placing the bare cell in an outer packaging shell, injecting the prepared electrolyte into the dried bare cell, and performing vacuum packaging, standing, formation, shaping and other processes to obtain the lithium ion battery.
Example 2
The cell preparation procedure is the same as that of example 1, except that: the compacted density of the negative active material coating on the negative pole piece obtained in the step 2 is 1.6g/cm3。
Example 3
The cell preparation procedure is the same as that of example 1, except that: the compacted density of the negative active material coating on the negative pole piece obtained in the step 2 is 1.7g/cm3。
Example 4
The cell preparation procedure is the same as that of example 1, except that: the compacted density of the negative active material coating on the negative pole piece obtained in the step 2 is 1.8g/cm3。
Example 5
The cell preparation procedure is the same as that of example 3, except that: the graphitization degree of the negative electrode active material selected in the step 2 is 92%.
Example 6
The cell preparation procedure is the same as that of example 3, except that: the graphitization degree of the negative electrode active material selected in the step 2 is 95%.
Example 7
The cell preparation procedure is the same as that of example 3, except that: the graphitization degree of the negative electrode active material selected in the step 2 is 97%.
Example 8
The cell preparation procedure is the same as that of example 3, except that: the positive active material selected in the step 1 is LiNi0.5Co0.25Mn0.25O2。
Example 9
The cell preparation procedure is the same as that of example 3, except that: the positive active material selected in the step 1 is LiNi1/3Co1/3Mn1/3O2。
Example 10
The cell preparation procedure is the same as that of example 3, except that: the positive active material selected in the step 1 is LiNi0.8Co0.1Mn0.1O2。
Example 11
The cell preparation procedure is the same as that of example 3, except that: the positive active material selected in the step 1 contains a coating layer and a coating element Ti.
Example 12
The cell preparation procedure is the same as that of example 3, except that: the anode active material selected in the step 1 contains a coating layer, the coating element is Ti, and the doping element is Al.
Comparative example 1
The preparation method is the same as that of example 1, except that: the compacted density of the negative active material coating on the negative pole piece obtained in the step 2 is 1.4g/cm3。
Comparative example 2
The preparation method is the same as that of example 1, except that: the compacted density of the negative active material coating on the negative pole piece obtained in the step 2 is 1.9g/cm3。
Comparative example 3
The preparation method is the same as that of example 3, except that: the graphitization degree of the negative electrode active material selected in the step 2 is 88%.
Comparative example 4
The preparation method is the same as that of example 3, except that: the graphitization degree of the negative electrode active material selected in the step 2 is 99%.
And (3) testing the cycle performance of the full battery:
the full cell cycle performance test of each example and comparative example was performed as follows:
carrying out first charging and discharging in an environment of 25 ℃, carrying out constant-current and constant-voltage charging under a charging current of 1.0C (namely a current value which completely discharges theoretical capacity within 1 h) until the upper limit voltage is 4.2V, then carrying out constant-current discharging under a discharging current of 1.0C until the final voltage is 2.8V, and recording the discharging capacity of the first circulation; and then performing a continuous charge-discharge cycle.
Cycle capacity retention rate ═ (discharge capacity at n-th cycle/discharge capacity at first cycle) × 100
Test of lithium deposition Rate
And (3) testing the lithium precipitation rate performance of the full battery:
in an environment of 25 ℃, a charge and discharge test was performed, and constant current discharge was performed at a discharge current of 1.0C (i.e., a current value at which the theoretical capacity was completely discharged within 1 hour) until the voltage was 2.8V. Then the battery is charged to 4.2V by constant current under the charging current of 1.0C, and the constant voltage charging is continued until the current is 0.05C, and the battery is in a full charge state. And (3) after the fully charged battery cell is kept stand for 5min, constant-current discharge is carried out to 2.8V under the discharge current of 1.0C, and the discharge capacity at the moment is the actual capacity of the battery cell under 1.0C and is marked as C0.
And then charging the battery cell to 4.2V at a constant current of xC0, then charging the battery cell to a constant voltage until the current is 0.05C0, standing for 5min, disassembling the battery cell, observing the condition of lithium precipitation on an interface, adjusting the charging rate until lithium precipitation occurs, and determining the lithium precipitation rate.
Testing of cell energy density
In an environment of 25 ℃, a charge and discharge test was performed, and constant current discharge was performed at a discharge current of 1.0C (i.e., a current value at which the theoretical capacity was completely discharged within 1 hour) until the voltage was 2.8V. Then the battery is charged to 4.2V by constant current under the charging current of 1.0C, and the constant voltage charging is continued until the current is 0.05C, and the battery is in a full charge state. And (3) after the fully charged battery cell is kept stand for 5min, constant-current discharge is carried out to 2.8V under the discharge current of 1.0C, and the discharge capacity at the moment is the actual capacity of the battery cell under 1.0C and is marked as C0.
Cell energy density (C0 × platform potential/cell weight)
The processing parameters, material performance parameters, and cell performance data for each example and comparative example are summarized in tables 1 and 2.
TABLE 1
Figure BDA0003269007320000111
Figure BDA0003269007320000121
TABLE 2
Figure BDA0003269007320000122
Analysis of test data:
1. when examples 1 to 4 and comparative examples 1 to 2 were analyzed, it was found that:
when the compacted density of the negative active material coating is not within the range specified in the present invention, the lithium deposition rate and 500-cycle capacity retention rate of the battery are significantly reduced. As can be seen from the analysis of examples 1 to 4, when the degree of graphitization of the negative electrode material was constant, the capacity retention rate at 500 cycles of the battery tended to be better as the compaction density of the negative electrode active material coating layer increased.
2. When examples 3, 5 to 7 and comparative examples 3 to 4 were analyzed, it was found that:
when the degree of graphitization of the negative electrode material is out of the range specified in the present invention, the battery cycle performance and lithium deposition are significantly deteriorated. As can be seen from analysis of examples 3 and 5 to 7, when the compaction density of the negative electrode active material coating layer is constant, the higher the graphitization degree is, the higher the energy density of the cell is.
3. Analysis of examples 3, 11 to 12 revealed that:
when the cathode material is doped and/or coated, the lithium deposition rate and the 500-cycle capacity retention rate of the battery can be further improved.
Appropriate changes and modifications to the embodiments described above will become apparent to those skilled in the art from the disclosure and teachings of the foregoing description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (9)

1. A lithium ion secondary battery comprises a positive pole piece, a negative pole piece, a separation film and electrolyte;
wherein the positive pole piece comprises a positive current collector and a positive active materialA coating layer containing a positive electrode active material having a general formula of LixNiaCobMcO2Wherein M is at least one selected from Mn and Al, x is 0.95-1.2, a is more than 0 and less than 1, b is more than 0 and less than 1, c is more than 0 and less than 1, and a + b + c is 1;
a coating layer is arranged on the surface of the positive electrode active material, and the coating layer contains Ti element; and is
The negative pole piece comprises a negative pole current collector and a negative pole active material coating, wherein the negative pole active material coating contains artificial graphite with the graphitization degree of 93-95% as a negative pole active material, and the compaction density of the negative pole active material coating is 1.6-1.7g/cm3。
2. The lithium ion secondary battery of claim 1, the positive electrode active material being selected from LiNi0.33Co0.33Mn0.33O2、LiNi0.5Co0.2Mn0.3O2、LiNi0.5Co0.25Mn0.25O2、LiNi0.6Co0.2Mn0.2O2、LiNi0.8Co0.1Mn0.1O2、LiNi0.85Co0.1Mn0.05O2、LiNi0.8Co0.15Al0.05O2At least one of (1).
3. The lithium ion secondary battery according to any one of claims 1 to 2, the positive electrode active material is present with a doping element that is at least one selected from Al, Zr, Ti, B, Mg, V, Cr, F.
4. The lithium ion secondary battery according to claim 1, wherein the surface of the negative electrode active material has a coating layer, and the coating layer is amorphous carbon.
5. The lithium ion secondary battery according to claim 4, wherein the amorphous carbon is obtained by carbonizing at least one material selected from coal pitch, petroleum pitch, mesophase pitch, epoxy resin, phenol resin, furfural resin, urea resin, polyvinyl alcohol, polyvinyl chloride, polyethylene glycol, polyethylene oxide, polyvinylidene fluoride, acrylic resin, and polyacrylonitrile.
6. The lithium ion secondary battery according to claim 4, wherein the content of the amorphous carbon is 2 to 13%, preferably 2 to 10%, with respect to the total weight of the anode active material.
7. The lithium ion secondary battery of any of claims 1-2, 4-6, wherein the weight of the positive electrode active material is 92% -98% of the positive electrode active material coating and the weight of the negative electrode active material is 92% -98% of the negative electrode active material coating.
8. The lithium ion secondary battery of claim 3, wherein the positive electrode active material comprises 92-98% of the positive electrode active material coating by weight, and the negative electrode active material comprises 92-98% of the negative electrode active material coating by weight.
9. The lithium ion secondary battery of claim 1, the positive active material comprising 92-98% by weight of the positive active material coating and the negative active material comprising 92-98% by weight of the negative active material coating.
CN202111095586.0A 2017-10-26 2017-10-26 Lithium ion secondary battery Pending CN113889620A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202111095586.0A CN113889620A (en) 2017-10-26 2017-10-26 Lithium ion secondary battery

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202111095586.0A CN113889620A (en) 2017-10-26 2017-10-26 Lithium ion secondary battery
CN201711012117.1A CN109713225A (en) 2017-10-26 2017-10-26 Lithium ion secondary battery

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
CN201711012117.1A Division CN109713225A (en) 2017-10-26 2017-10-26 Lithium ion secondary battery

Publications (1)

Publication Number Publication Date
CN113889620A true CN113889620A (en) 2022-01-04

Family

ID=66253395

Family Applications (2)

Application Number Title Priority Date Filing Date
CN202111095586.0A Pending CN113889620A (en) 2017-10-26 2017-10-26 Lithium ion secondary battery
CN201711012117.1A Pending CN109713225A (en) 2017-10-26 2017-10-26 Lithium ion secondary battery

Family Applications After (1)

Application Number Title Priority Date Filing Date
CN201711012117.1A Pending CN109713225A (en) 2017-10-26 2017-10-26 Lithium ion secondary battery

Country Status (1)

Country Link
CN (2) CN113889620A (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113130971A (en) * 2019-12-31 2021-07-16 深圳新宙邦科技股份有限公司 Lithium ion battery
JP7263627B2 (en) * 2020-04-30 2023-04-24 寧徳時代新能源科技股▲分▼有限公司 NEGATIVE ACTIVE MATERIAL AND MANUFACTURING METHOD THEREFOR, SECONDARY BATTERY AND APPARATUS CONTAINING SECONDARY BATTERY
CN115911757B (en) * 2023-03-08 2023-07-11 宁德时代新能源科技股份有限公司 Secondary battery and electricity utilization device

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103441305A (en) * 2013-08-27 2013-12-11 深圳市贝特瑞新能源材料股份有限公司 Power and energy storage lithium-ion battery and preparation method thereof
CN104085883A (en) * 2014-07-09 2014-10-08 深圳市贝特瑞新能源材料股份有限公司 Artificial graphite negative electrode material for lithium ion battery and preparation method thereof
US20150099180A1 (en) * 2012-05-21 2015-04-09 Imerys Graphite & Carbon Switzerland Ltd. Surface-modified carbon hybrid particles, methods of making, and applications of the same
CN105655542A (en) * 2014-11-14 2016-06-08 青岛灵科新能源有限公司 A lithium ion battery anode and a preparing method thereof
CN105789627A (en) * 2016-03-22 2016-07-20 福建翔丰华新能源材料有限公司 Preparation method of high-performance graphite negative electrode material for lithium ion battery
CN106252613A (en) * 2015-06-10 2016-12-21 旭硝子株式会社 Lithium-contained composite oxide, positive active material, lithium ion secondary battery anode and lithium rechargeable battery
CN107240684A (en) * 2017-06-08 2017-10-10 华中科技大学 The preparation method and product for the nickelic positive electrode of lithium battery that a kind of surface is modified

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103618084A (en) * 2013-11-21 2014-03-05 刘铁建 Mixed positive material of lithium-ion power battery
CN104810508B (en) * 2015-03-30 2018-05-22 深圳市金润能源材料有限公司 Cell negative electrode material and preparation method thereof

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150099180A1 (en) * 2012-05-21 2015-04-09 Imerys Graphite & Carbon Switzerland Ltd. Surface-modified carbon hybrid particles, methods of making, and applications of the same
CN103441305A (en) * 2013-08-27 2013-12-11 深圳市贝特瑞新能源材料股份有限公司 Power and energy storage lithium-ion battery and preparation method thereof
CN104085883A (en) * 2014-07-09 2014-10-08 深圳市贝特瑞新能源材料股份有限公司 Artificial graphite negative electrode material for lithium ion battery and preparation method thereof
CN105655542A (en) * 2014-11-14 2016-06-08 青岛灵科新能源有限公司 A lithium ion battery anode and a preparing method thereof
CN106252613A (en) * 2015-06-10 2016-12-21 旭硝子株式会社 Lithium-contained composite oxide, positive active material, lithium ion secondary battery anode and lithium rechargeable battery
CN105789627A (en) * 2016-03-22 2016-07-20 福建翔丰华新能源材料有限公司 Preparation method of high-performance graphite negative electrode material for lithium ion battery
CN107240684A (en) * 2017-06-08 2017-10-10 华中科技大学 The preparation method and product for the nickelic positive electrode of lithium battery that a kind of surface is modified

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
LEI ZHANG等: "Graphitized porous carbon microspheres assembled with carbon black nanoparticles as improved anode materials in Li-ion batteries", 《JOURNAL OF MATERIALS CHEMISTRY A》 *

Also Published As

Publication number Publication date
CN109713225A (en) 2019-05-03

Similar Documents

Publication Publication Date Title
JP7280942B2 (en) Negative electrode materials and negative electrodes containing said negative electrode materials, and electrochemical devices
US11417869B2 (en) Lithium ion secondary battery
CN108807974B (en) Lithium ion battery
CN110010903B (en) Positive pole piece and battery
JP7406625B2 (en) Artificial graphite, secondary batteries, manufacturing methods and equipment
JP6429172B2 (en) Positive electrode active material having excellent electrochemical performance and lithium secondary battery including the same
KR102542649B1 (en) Negative electrode for rechargeable lithium battery and rechargeable lithium battery including the same
KR101211327B1 (en) Anode active material for secondary battery and method for preparing the same
CN109119592B (en) Lithium titanate negative electrode piece, preparation method and lithium titanate battery
KR20200036424A (en) Positive active material for rechargeable lithium battery, method of preparing the same, and rechargeable lithium battery including the same
CN110828774B (en) Negative electrode of lithium battery, preparation method of negative electrode and lithium battery
KR20200090727A (en) Positive active material for rechargeable lithium battery, method of preparing the same, and rechargeable lithium battery including the same
CN110265626B (en) Positive pole piece, preparation method thereof and lithium ion secondary battery
KR20190001191A (en) Positive Electrode Material for Lithium-Ion Batteries and Lithium-Ion Battery Having the Same
CN114223073A (en) Negative active material, method of preparing the same, secondary battery, and device including the secondary battery
CN113889620A (en) Lithium ion secondary battery
US11710822B2 (en) Composite graphite material, secondary battery, apparatus and preparation method thereof
KR101592773B1 (en) Anode active material and secondary battery comprising the same
KR20200091055A (en) Negative electrode active material for secondary battery, negative electrode including same and manufacturing method thereof
CN115275166A (en) Long-life graphite composite material and preparation method thereof
EP3955348A1 (en) Negative electrode active material and preparation method therefor, secondary battery, and device including secondary battery
KR20220064385A (en) Composite graphite material and manufacturing method thereof, secondary battery and device
JP2000353545A (en) Nonaqueous electrolyte secondary battery
CN116565135A (en) Electrode plate, preparation method thereof and energy storage device
CN117293400A (en) Lithium ion battery, preparation method thereof and electric equipment

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
RJ01 Rejection of invention patent application after publication

Application publication date: 20220104

RJ01 Rejection of invention patent application after publication