CN116093415A - Lithium ion battery - Google Patents

Lithium ion battery Download PDF

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Publication number
CN116093415A
CN116093415A CN202310020622.XA CN202310020622A CN116093415A CN 116093415 A CN116093415 A CN 116093415A CN 202310020622 A CN202310020622 A CN 202310020622A CN 116093415 A CN116093415 A CN 116093415A
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lithium
negative electrode
active material
ion battery
polymer
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赵玉楠
彭冲
谢朵
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Zhuhai Cosmx Battery Co Ltd
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Zhuhai Cosmx Battery Co Ltd
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    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • 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
    • H01M10/058—Construction or manufacture
    • H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
    • 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
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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

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Abstract

The invention provides a lithium ion battery. The lithium ion battery comprises an electrolyte, a positive plate, a diaphragm and a negative plate; the negative electrode plate comprises a current collector, a first negative electrode active material layer and a lithium supplementing layer, wherein the first negative electrode active material layer and the lithium supplementing layer are arranged on at least one side surface of the current collector, and the first negative electrode active material layer comprises a silicon-based material. According to the invention, the polymer is added into the electrolyte, so that the problems of uneven local interface, expansion, poor diaphragm bonding effect, uneven local lithium intercalation and rapid capacity attenuation caused by inconsistent local side reaction degree of the lithium ion battery cathode are solved.

Description

Lithium ion battery
Technical Field
The application relates to the technical field of batteries, in particular to a lithium ion battery.
Background
The polymer lithium ion battery has the advantages of high volume specific energy and mass specific energy, no memory effect, good cycle life, environmental friendliness and the like, and plays a dominant role in the market direction of electronic products. In practice, the fast charge performance and the high energy density performance have certain mutual exclusion properties, and it is difficult to achieve the compatibility.
Silicon carbon or silicon oxygen is a cathode material of great interest due to its high gram capacity, and will be a hot spot of research in the next few years. However, in a silicon-based negative electrode battery system, the initial charge consumes about 20% of the lithium source, resulting in a silicon-based negative electrode having a lower initial efficiency relative to other negative electrode materials. For example, the first efficiency of pure graphite (the graphite layer can be natural graphite or lamellar graphite) is 92-94%, the first efficiency of lithium cobaltate is 94-97%, and the first efficiency of silicon cathode is 78-82%. In order to improve the first efficiency of the silicon-based negative electrode, the energy density of the battery is further improved, and the first efficiency of the battery is improved through a pre-lithiation technology.
At present, the simplest processing performance is that a lithium foil is attached to the surface of a pole piece in a rolling way, but the process has the following problems that after liquid injection, electrolyte and a lithium belt can generate some side reactions to cover the surface of a lithium supplementing pole piece, local thickness difference is caused by inconsistent local side reaction degree, the side reactions are mostly oxides and hydroxides of lithium, the adhesiveness between the lithium foil and a battery cell diaphragm is poor, and the lithium is easy to locally take off and intercalate in the charging and discharging process; in addition, the silicon-based negative electrode is expanded circularly, and the battery cell is easy to deform further to deteriorate circularly.
Disclosure of Invention
In view of this, the present invention provides a lithium ion battery. The lithium ion battery solves the problems of uneven local interface, poor diaphragm bonding effect, uneven local lithium intercalation and rapid capacity decay of the silicon-based negative electrode after expansion.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a lithium ion battery, which comprises an electrolyte, a positive plate, a diaphragm and a negative plate;
the negative electrode plate comprises a current collector, a first negative electrode active material layer and a lithium supplementing layer, wherein the first negative electrode active material layer and the lithium supplementing layer are arranged on at least one side surface of the current collector, and the first negative electrode active material layer comprises a silicon-based material;
the electrolyte includes a polymer.
In a specific embodiment of the present invention, the electrolyte may be an electrolyte solution.
Preferably, the electrolyte is a semi-gel electrolyte.
Preferably, the electrolyte includes an organic solvent, a lithium salt, a functional additive, and a polymer. The electrolyte and/or polymer are distributed on the surfaces of the negative electrode plate and the lithium supplementing layer, the gaps between the lithium supplementing layer and the diaphragm and the gaps between the positive electrode particles and the negative electrode particles.
Preferably, the polymer comprises an acrylic polymer.
Preferably, the polymer comprises a polymer monomer;
the polymer monomer comprises at least one of acrylic ester, methyl methacrylate, ethyl methacrylate, butyl methacrylate and N, N-methylene bisacrylamide; the polymer has viscosity, so that the viscosity of the electrolyte is increased, and the sliding problem of the lithium supplementing layer and the negative plate and the lithium supplementing layer and the diaphragm in the silicon-containing negative plate lithium ion battery is effectively solved.
Preferably, the monomers of the polymer comprise acrylates and/or N, N-methylenebisacrylamide.
Preferably, the degree of polymerization of the polymer is the number of repeated units continuously occurring in the polymer molecular chain, expressed as n, n=2 to 100;
the degree of polymerization refers to the number of repeating units (or mer) that occur continuously in the polymer molecular chain, and is denoted by n. Preferably, the polymerization degree n=2 to 100, for example, 2 to 5, 5 to 10, 10 to 20, 20 to 30, 30 to 40, 40 to 50, 50 to 60, 60 to 70, 70 to 80, 80 to 90, 90 to 100, 15 to 25, 25 to 35, 35 to 45, 45 to 55, 55 to 65, 65 to 75, 75 to 85, 85 to 95, etc. of the polymer. In the range, the polymer has certain viscosity, so that the sliding problem of the lithium supplementing layer and the negative electrode piece and the lithium supplementing layer and the diaphragm in the silicon-containing negative electrode piece lithium ion battery can be solved. Meanwhile, the polymerization degree of the polymer is within the range, so that ion migration is not influenced, the conductivity of the electrolyte is not influenced, and excellent electrochemical performance is obtained.
Preferably, the degree of polymerization n=10 to 100 of the polymer;
more preferably, the degree of polymerization n=50 to 100 of the polymer.
Preferably, the acrylate polymer backbone or grafted side chains contain hydrophilic groups, carboxyl groups, which are typically crimped to a bulk form, at a pH of 3 to 3.5. After the alkaline system is added, the molecules are ionized and generate negative charges along the main chain of the polymer, the repulsion between the like charges promotes the molecular chains to relax, a network structure is formed, the swelling and thickening phenomenon is generated, the viscosity of the system is increased, and the purpose of thickening is achieved.
Preferably, the polymer comprises carboxyl groups (-COOH), the number of which is greater than or equal to n.
In the invention, the polymer is semi-gel electrolyte, so that the viscosity of the electrolyte is increased, the positive plate, the diaphragm and the negative plate can be effectively bonded together, the cementing effect of a colloid product can reduce the sliding between lithium foil metal on the surface of the negative plate and the diaphragm, the integrity of the battery is improved, and the problem that a lithium supplementing layer is incompatible with the diaphragm and slides is solved; according to the technical scheme, the pores between the diaphragm coating and the lithium foil on the outer and inner sides of the negative electrode are reduced, meanwhile, lithium ions are more uniformly inserted during charge and discharge, and local deformation caused by different side reaction degrees of electrolyte and lithium metal is reduced. Therefore, the invention solves the problem of local deformation caused by poor consistency of lithium ion deintercalation in circulation, and solves the problem of lithium precipitation from black spots caused by local deformation. Further improving the cycle retention and expansion of the silicon-containing anode cell.
Preferably, the content of the polymer in the electrolyte is 1wt% to 20wt%. For example 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%. The polymer content is too small to cause gelation reaction; the polymer content is too large, the gelation reaction is too severe, and potential safety hazards exist.
Preferably, the content of the polymer in the electrolyte is 1wt% to 10wt%.
In the examples provided herein, the polymer content in the electrolyte is 1wt% to 5wt%.
Preferably, the lithium supplementing layer is provided on a surface of the separator on the negative electrode sheet side.
In the embodiments provided by the invention, the electrolyte and/or polymer is distributed in the gaps between the lithium supplementing layer and the diaphragm, the gaps between the active material particles of the positive plate and/or the negative plate, and the inner cavity of the battery.
Preferably, the electrolyte and/or polymer is distributed between the lithium supplementing layer and the diaphragm, and the electrolyte and/or polymer can bond the lithium supplementing layer and the diaphragm together to prevent sliding between the lithium supplementing layer and the diaphragm.
Preferably, the electrolyte and/or polymer is distributed in the gaps of the active material particles of the negative electrode sheet, and the electrolyte and/or polymer can bond the lithium supplementing layer and the negative electrode sheet main body together to prevent sliding between the lithium supplementing layer and the negative electrode sheet main body.
Preferably, the electrolyte and/or the polymer are distributed in the whole battery cavity, the polymer in the electrolyte can fully infiltrate the battery cavity, the diaphragm, the positive plate, the negative plate and the like along with the electrolyte, the positive plate, the diaphragm and the negative plate are bonded together to form a whole, and the problem that the lithium supplementing layer and the diaphragm are incompatible and slide is solved.
Preferably, the organic solvent comprises a carbonate and/or a carboxylate;
preferably, the carboxylic acid ester comprises at least one of the following solvents, either fluorinated or unsubstituted: propyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl acetate, isopentyl acetate, propyl propionate, ethyl propionate, methyl butyrate, and ethyl n-butyrate;
preferably, the carbonate comprises at least one of the following solvents, either fluorinated or unsubstituted: ethylene carbonate (ethylene carbonate), propylene carbonate, dimethyl carbonate, diethyl carbonate, and methylethyl carbonate.
Preferably, the lithium salt includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorosulfimide, lithium bistrifluoromethylsulfonyl imide, lithium difluorobisoxalato phosphate, lithium tetrafluoroborate, lithium bisoxalato borate, lithium hexafluoroantimonate, lithium hexafluoroarsonate, lithium bis (trifluoromethylsulfonyl) imide, lithium bis (pentafluoroethylsulfonyl) imide, lithium tris (trifluoromethylsulfonyl) methyllithium or lithium bis (trifluoromethylsulfonyl) imide;
preferably, the content of lithium salt in the electrolyte is 11wt% to 18wt%.
Preferably, the functional additive includes at least one of a cyclic carbonate additive, a cyclic sulfonate additive, a nitrile additive, and a lithium salt additive.
Preferably, the cyclic carbonate additive comprises at least one of fluoroethylene carbonate, vinylene carbonate, ethylene carbonate; the cyclic carbonate additive can easily form a stable SEI film on the surface of the negative electrode, has excellent high-low temperature performance and anti-flatulence performance, and can effectively improve the capacity and the cycle performance of the battery.
Preferably, the cyclic sultone additive includes at least one of 1, 3-propane sultone, 1, 3-propenesulfonic acid lactone, 2, 4-butane sultone, and 1, 4-butane sultone; the cyclic sultone additive has a functional group-SO 3 Decomposition products thereof such as RSO 3 Li and the like have higher ion conductivity and excellent high-temperature performance, meanwhile, a CEI film with low impedance can be formed on the surface of the positive electrode, the subsequent electrolyte decomposition is inhibited, and when the lithium ion battery is used for a cobalt-free positive electrode material battery, the metal ions can be inhibited from being dissolved out and adsorbed on the surface of the negative electrode, so that the high-temperature cycle performance of the battery is greatly improved.
Preferably, the nitrile additive comprises at least one of 1,3, 6-hexanetrinitrile, succinonitrile, adiponitrile and glutaronitrile; the nitrile additive is beneficial to better protecting the positive electrode, thereby improving the cycle performance.
Preferably, the lithium salt type additive comprises at least one of lithium difluorooxalato borate, lithium difluorophosphate, lithium difluorodioxaato phosphate and lithium dioxaato borate; the lithium salt type additive can improve the cycle performance, high temperature performance, safety performance and the like of the battery, thereby improving the comprehensive performance of the battery.
Preferably, the content of the functional additive in the electrolyte is 15wt% or less.
Preferably, the silicon-based material comprises silicon, siO x (0 < x < 2), and silicon-carbon composite.
Preferably, in the silicon-carbon composite, the mass ratio of the carbon-based negative electrode material to the silicon-based negative electrode material is 10:0-1:19.
Preferably, the negative electrode sheet further includes a second negative electrode active material layer disposed between the current collector and the first negative electrode active material layer;
preferably, the active material of the second anode active material layer includes a carbon material.
Preferably, the carbon material includes at least one of artificial graphite, natural graphite, mesophase carbon microspheres, hard carbon, and soft carbon.
Preferably, the first negative electrode active material layer or the second negative electrode active material layer further includes at least one of a conductive agent, a binder, and a dispersant.
Preferably, the conductive agent comprises at least one of conductive carbon black, acetylene black, ketjen black, conductive graphite, conductive carbon fiber, carbon nanotube, metal powder and carbon fiber;
preferably, the binder comprises at least one of ethylene, styrene-butadiene latex, polytetrafluoroethylene, polyethylene oxide;
preferably, the dispersing agent comprises at least one of carboxymethyl cellulose and sodium carboxymethyl cellulose.
Preferably, the first negative electrode active material layer or the second negative electrode active material layer comprises the following components in percentage by mass: 70 to 99.7 weight percent of active substance, 0.1 to 10 weight percent of conductive agent, 0.1 to 10 weight percent of binder and 0.1 to 10 weight percent of dispersing agent.
Preferably, the thickness of the lithium supplementing layer is 1 to 5. Mu.m.
Preferably, the lithium supplementing layer is a lithium foil and/or a lithium alloy foil.
In an embodiment provided by the present invention, a positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer coated on one or both side surfaces of the positive electrode current collector, the positive electrode active material layer including a positive electrode active material, a conductive agent, a binder, and a dispersing agent.
Preferably, the positive electrode active material layer comprises the following components in percentage by mass: 70 to 99.7 weight percent of positive electrode active material, 0.1 to 10 weight percent of conductive agent, 0.1 to 10 weight percent of binder and 0.1 to 10 weight percent of dispersing agent.
Preferably, the positive electrode active material comprises one or more of transition metal lithium oxide, lithium iron phosphate, lithium manganese iron phosphate and lithium-rich manganese-based material; the chemical formula of the transition metal lithium oxide is Li 1+x Ni y Co z M (1-y-z) O 2 Wherein, -0.1 is less than or equal to x is less than or equal to 1; y is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 1, and y+z is more than or equal to 0 and less than or equal to 1; wherein M is one or more of Mg, zn, ga, ba, al, fe, cr, sn, V, mn, sc, ti, nb, mo, zr.
The invention also provides a preparation method of the lithium ion battery, which comprises the following steps: and stacking the positive plate, the diaphragm and the negative plate to obtain a stacked core, or winding the stacked positive plate, the diaphragm and the negative plate to obtain a rolled core, placing the stacked core or the rolled core in an outer package, injecting electrolyte into the outer package, and performing thermocompression formation to obtain the lithium ion battery.
Preferably, the temperature of the thermocompression is 45-90 ℃ and the pressure is 0.5-1 MPa.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the technical scheme, the sliding problem of the lithium supplementing layer and the negative plate and the sliding problem of the lithium supplementing layer and the diaphragm in the silicon-doped lithium foil lithium supplementing battery can be effectively solved, and the problem of poor adhesion of the lithium supplementing negative plate and the diaphragm can be solved;
(2) According to the technical scheme, the problem of local unevenness of the battery caused by expansion of the silicon-based negative electrode can be effectively solved, and the uniformity of lithium intercalation during charging is improved;
(3) The electrolyte is filled among the anode particles, so that the influence of particle pore electric contact deactivation caused by irreversible expansion of the silicon anode is improved, the circulation and expansion performance of a silicon anode system are improved, and the cycle life of a lithium ion battery is further improved;
(4) The SEI film uniformity and compactness on the surface of the negative electrode are improved, and the cycle life and the battery cycle deformation problem of the lithium-supplementing silicon-containing negative electrode are well improved.
Drawings
Fig. 1 is a schematic structural diagram of a negative plate in embodiment 1 of the present invention;
FIG. 2 is a 3D profile of two cells prepared in example 1;
fig. 3 is a 3D profile of two cells prepared in comparative example 1;
FIG. 4 is a cyclic expansion diagram of a battery;
fig. 5 is a graph showing the capacity retention ratio of the battery;
fig. 6 is a schematic structural diagram of a negative plate in embodiment 2 of the present invention;
FIG. 7 is a cyclic expansion diagram of a battery;
fig. 8 is a graph showing the capacity retention ratio of the battery.
The reference numerals are as follows:
100 lithium supplementing layers, 110 first negative electrode active material layers, 120 second negative electrode active material layers, 130 current collectors.
Detailed Description
The invention discloses a lithium ion battery, and a person skilled in the art can properly improve the technological parameters by referring to the content of the invention. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and are deemed to be included in the present invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that variations and modifications can be made in the methods and applications described herein, and in the practice and application of the techniques of this invention, without departing from the spirit or scope of the invention.
The reagents, instruments, materials, etc. used in the present invention are commercially available.
The invention is further illustrated by the following examples:
example 1
1. Structure of battery
The battery comprises a semi-gel electrolyte, a positive plate, a diaphragm and a negative plate which are sequentially arranged;
as shown in fig. 1, the negative electrode sheet includes a lithium supplementing layer, a first negative electrode active material layer, a second negative electrode active material layer, and a current collector, which are sequentially disposed.
The active material in the first anode active material layer is a silicon-carbon composite;
the active material in the second anode active material layer is natural graphite.
2. Method for producing battery
Firstly, preparing a positive pole piece:
adding a main material of a lithium cobalt oxide anode, conductive carbon black of a conductive agent and polyvinylidene fluoride into a stirring tank according to the mass ratio of 97:1.5:1.5, adding an NMP solvent to prepare anode slurry, coating the slurry on an aluminum foil by using a coating machine, drying at 120 ℃ for 8 hours, firstly cutting into small strips after drying, cleaning by using a scraper, washing out the welding position of the anode lug, compacting by using a roller press, and welding the aluminum lug to obtain the anode pole piece.
Secondly, preparing active material slurry:
preparing a first active material slurry: adding graphite and silicon carbon (the mass ratio is 9:1) serving as a first anode active substance, conductive carbon black serving as a conductive agent, styrene-butadiene latex serving as a binder and sodium carboxymethyl cellulose serving as a dispersing agent into a stirring tank according to the mass ratio of 94.5:2.0:2.0:1.5, adding deionized water to prepare anode slurry, and stirring by a well-known batching process to obtain slurry with the solid content of 40% -45%;
preparing a second active material slurry: adding second negative active material artificial graphite, conductive carbon black serving as a conductive agent, styrene-butadiene latex serving as a binder and sodium carboxymethyl cellulose serving as a dispersing agent into a stirring tank according to a mass ratio of 96:0.5:1.5:2.0, adding deionized water to prepare negative electrode slurry, and stirring by a well-known batching process to obtain slurry with a solid content of 42% -48%;
thirdly, preparing a negative plate:
the two active material slurries were coated on the negative current collector copper foil by coating twice with a skip coater. And drying the prepared negative plate at the temperature of 100 ℃, rolling, slitting into strips, cleaning tab grooves by laser, and welding nickel tabs to obtain the negative plate.
Rolling a lithium foil belt with the thickness of 100 mu m into an ultrathin lithium belt with the required thickness by two rolling rollers, wherein the thickness of the lithium belt is 2-20 mu m, and then rolling and adhering the ultrathin lithium belt on the surface of a negative plate, wherein the thickness of a lithium supplementing layer is 1-5 mu m;
fourth, electrolyte preparation:
in a dry argon atmosphere glove box, ethylene Carbonate (EC), propylene Carbonate (PC), ethylmethyl carbonate (EMC) and diethyl carbonate (DEC) were mixed according to the mass ratio EC: PC: EMC: dec=10:30:30:30, then 12% fluoroethylene carbonate is added, and lithium salt LiPF is added after dissolution and sufficient stirring 6 (LiPF 6 The concentration of (2) was 1 mol/L) and the acrylic acid ester (2.8%) and N, N-methylenebisacrylamide (0.5%) were uniformly mixed to obtain an electrolyte.
Fifthly, assembling the battery cell:
and (3) winding the positive and negative electrode plates obtained in the two steps and the diaphragm together to form a winding core, packaging by using an aluminum plastic film, baking to remove water, injecting electrolyte, and performing thermocompression forming process to obtain the semi-gel electrolyte battery core.
Comparative example 1:
the difference from example 1 is that: the electrolyte of this comparative example was not added with acrylate and N, N-methylenebisacrylamide.
Cell performance test 1:
the batteries of example 1 and comparative example 1 were subjected to performance test.
1. Thickness of cell
The specific test method comprises the following steps:
and (3) charging the battery cell to 3.87V at constant current and constant voltage, and recording the thickness of the battery cell by using a thickness gauge.
The experimental results are as follows:
table 1 thickness of comparative cell
Figure BDA0004041791910000091
As can be seen from the above table, the average value of the cell thickness of example 1 is 4.705mm, the average value of the cell thickness of comparative example 1 is 4.76mm, the overall average value of the cell thickness of example 1 is smaller than that of comparative example 1, and it can be seen that the adhesion of the separator and the pole piece improves the cell flatness.
2. Flatness of cell after circulation
The specific test method comprises the following steps:
and comparing the flatness of the battery cells after the circulation, and comparing the flatness test of the battery cells by a 3D profiler, wherein the flatness test is shown in fig. 2 and 3.
From fig. 2 and 3, it can be seen that the cell of example 1 has good flatness after cycling and no significant deformation occurs.
3. Expansion properties
The specific test method comprises the following steps:
charging the battery cell with 0.7C constant current and constant voltage to full power every 100 times, and recording the thickness data of the battery cell; cell expansion = (full cell thickness after cycling-cell thickness before cycling)/cell thickness before cycling
The cell swelling performance was compared.
As can be seen from fig. 4, the cyclic expansion of example 1 after the cycle can be improved by about 1%, and a remarkable effect is obtained.
4. Battery capacity retention rate
The specific test method comprises the following steps:
600 times of 3C constant-current constant-voltage charge/1C discharge cycles.
The experimental results are shown in FIG. 5. As can be seen from fig. 5, the capacity retention rate of the cell of example 1 is significantly higher than that of the cell of comparative example 1, showing that the cell of the present invention has a better cycle life.
Example 2
1. Structure of battery
The battery comprises a semi-gel electrolyte, a positive plate, a diaphragm and a negative plate which are sequentially arranged;
as shown in fig. 6, the negative electrode sheet includes a lithium supplementing layer, a first negative electrode active material layer, and a current collector, which are sequentially disposed.
The active material in the first anode active material layer is a silicon-carbon composite.
2. Method for producing battery
Firstly, preparing a positive pole piece:
adding a main material of a lithium cobalt oxide anode, conductive carbon black of a conductive agent and polyvinylidene fluoride into a stirring tank according to the mass ratio of 97:1.5:1.5, adding an NMP solvent to prepare anode slurry, coating the slurry on an aluminum foil by using a coating machine, drying at 120 ℃ for 8 hours, firstly cutting into small strips after drying, cleaning by using a scraper, washing out the welding position of the anode lug, compacting by using a roller press, and welding the aluminum lug to obtain the anode pole piece.
Secondly, preparing active material slurry:
preparing a first active material slurry: adding graphite and silicon carbon (the mass ratio is 9:1) serving as a first anode active substance, conductive carbon black serving as a conductive agent, styrene-butadiene latex serving as a binder and sodium carboxymethyl cellulose serving as a dispersing agent into a stirring tank according to the mass ratio of 94.5:2.0:2.0:1.5, adding deionized water to prepare anode slurry, and stirring by a well-known batching process to obtain slurry with the solid content of 40% -45%;
thirdly, preparing a negative plate:
the active material slurry was coated on a negative current collector copper foil by a skip coater. And drying the prepared negative plate at the temperature of 100 ℃, rolling, slitting into strips, cleaning tab grooves by laser, and welding nickel tabs to obtain the negative plate.
Rolling a lithium foil belt with the thickness of 100 mu m into an ultrathin lithium belt with the required thickness by two rolling rollers, wherein the thickness of the lithium belt is 2-20 mu m, and then rolling and adhering the ultrathin lithium belt on the surface of a negative plate, wherein the thickness of a lithium supplementing layer is 1-5 mu m;
fourth, electrolyte preparation:
ethylene Carbonate (EC), propylene carbonate were reacted in a dry argon atmosphere glove box(PC), methyl ethyl carbonate (EMC) and diethyl carbonate (DEC) are mixed according to the mass ratio of EC: PC: EMC: dec=10:30:30:30, then 12% fluoroethylene carbonate is added, and lithium salt LiPF is added after dissolution and sufficient stirring 6 (LiPF 6 The concentration of (2) was 1 mol/L) and the acrylic acid ester (2.8%) and N, N-methylenebisacrylamide (0.5%) were uniformly mixed to obtain an electrolyte.
Fifthly, assembling the battery cell:
and (3) winding the positive and negative electrode plates obtained in the two steps and the diaphragm together to form a winding core, packaging by using an aluminum plastic film, baking to remove water, injecting electrolyte, and performing thermocompression forming process to obtain the semi-gel electrolyte battery core.
Comparative example 2:
the difference from example 2 is that: the electrolyte of this comparative example was not added with acrylate and N, N-methylenebisacrylamide.
Cell performance test 2:
the batteries of example 2 and comparative example 2 were subjected to performance test.
1. Thickness of cell
The specific test method comprises the following steps:
and (3) charging the battery cell to 3.87V at constant current and constant voltage, and recording the thickness of the battery cell by using a thickness gauge.
The experimental results are as follows:
table 2 comparative cell thickness
Figure BDA0004041791910000121
As can be seen from the above table, the average value of the cell thickness of example 2 is 4.708mm, the average value of the cell thickness of comparative example 2 is 4.76mm, the overall average value of the cell thickness of example 2 is smaller than that of comparative example 2, and it can be seen that the adhesion of the separator and the pole piece improves the cell flatness.
2. Expansion properties
The specific test method comprises the following steps:
charging the battery cell with 0.7C constant current and constant voltage to full power every 100 times, and recording the thickness data of the battery cell; cell expansion = (full cell thickness after cycling-cell thickness before cycling)/cell thickness before cycling
The cell swelling performance was compared.
As can be seen from fig. 7, the cyclic expansion of example 2 after the cycle can be improved by about 2%, and a remarkable effect is obtained.
3. Battery capacity retention rate
The specific test method comprises the following steps:
600 times of 3C constant-current constant-voltage charge/1C discharge cycles.
The experimental results are shown in FIG. 8. As can be seen from fig. 8, the capacity retention rate of the cell of example 2 is significantly higher than that of the cell of comparative example 2, showing that the cell of the present invention has a better cycle life.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.

Claims (10)

1. The lithium ion battery is characterized by comprising an electrolyte, a positive plate, a diaphragm and a negative plate;
the negative electrode plate comprises a current collector, a first negative electrode active material layer and a lithium supplementing layer, wherein the first negative electrode active material layer and the lithium supplementing layer are arranged on at least one side surface of the current collector, and the first negative electrode active material layer comprises a silicon-based material;
the electrolyte includes a polymer.
2. The lithium ion battery of claim 1, wherein the electrolyte is a semi-gel state electrolyte;
preferably, the electrolyte includes an organic solvent, a lithium salt, a functional additive, and a polymer.
3. The lithium ion battery of any of claims 1-2, wherein the polymer comprises an acrylic polymer;
and/or the degree of polymerization of the polymer is the number of times of repeated units continuously appearing in the polymer molecular chain, expressed as n, n=2 to 100;
and/or the polymer comprises carboxyl groups, wherein the number of the carboxyl groups is greater than or equal to n;
and/or the content of the polymer in the electrolyte is 1-20wt%.
4. The lithium ion battery of claim 1, wherein the lithium supplementing layer is disposed on a side surface of the negative electrode sheet that is attached to the separator.
5. The lithium ion battery according to any of claims 1-2, wherein the electrolyte and/or polymer is distributed in the cell cavity in the gap between the lithium-compensating layer and the separator, the active material particle gap of the positive and/or negative electrode sheet.
6. The lithium ion battery of claim 2, wherein the organic solvent comprises a carbonate and/or a carboxylate;
and/or the lithium salt comprises at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorooxalato borate, lithium difluorosulfimide, lithium bistrifluoromethylsulfonyl imide, lithium difluorobisoxalato phosphate, lithium tetrafluoroborate, lithium bisoxalato borate, lithium hexafluoroantimonate, lithium hexafluoroarsenate, lithium bis (trifluoromethylsulfonyl) imide, lithium bis (pentafluoroethylsulfonyl) imide, lithium tris (trifluoromethylsulfonyl) methyllithium or lithium bis (trifluoromethylsulfonyl) imide;
and/or the functional additive comprises at least one of a cyclic carbonate additive, a cyclic sulfonate additive, a nitrile additive and a lithium salt additive.
7. The lithium ion battery of claim 1, wherein the silicon-based material comprises silicon, siO x (0 < x < 2), at least one of silicon carbon composite;
preferably, in the silicon-carbon composite, the mass ratio of the carbon-based negative electrode material to the silicon-based negative electrode material is 10:0-1:19.
8. The lithium ion battery of claim 1, wherein the negative electrode sheet further comprises a second negative electrode active material layer disposed between the current collector and the first negative electrode active material layer.
9. The lithium ion battery of claim 8, wherein the active material of the second anode active material layer comprises a carbon material;
preferably, the carbon material comprises at least one of artificial graphite, natural graphite, mesophase carbon microspheres, hard carbon, soft carbon.
10. The lithium ion battery of any of claims 1-9, wherein the thickness of the lithium-compensating layer is 1-5 μιη; and/or the lithium supplementing layer is a lithium foil and/or a lithium alloy foil.
CN202310020622.XA 2023-01-06 2023-01-06 Lithium ion battery Pending CN116093415A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116705981A (en) * 2023-07-27 2023-09-05 宁德时代新能源科技股份有限公司 Negative electrode plate, preparation method thereof, battery and electric equipment
CN117747746A (en) * 2023-12-29 2024-03-22 蜂巢能源科技股份有限公司 Lithium supplementing dry electrode, preparation method thereof, electrode preparation equipment and application

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116705981A (en) * 2023-07-27 2023-09-05 宁德时代新能源科技股份有限公司 Negative electrode plate, preparation method thereof, battery and electric equipment
CN116705981B (en) * 2023-07-27 2024-05-03 宁德时代新能源科技股份有限公司 Negative electrode plate, preparation method thereof, battery and electric equipment
CN117747746A (en) * 2023-12-29 2024-03-22 蜂巢能源科技股份有限公司 Lithium supplementing dry electrode, preparation method thereof, electrode preparation equipment and application

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