WO2023174299A1 - Negative electrode plate for lithium battery, and preparation method and application of negative electrode plate - Google Patents

Abstract

Disclosed are a negative electrode plate for a lithium battery, and a preparation method and an application of the negative electrode plate. The negative electrode plate of the present invention comprises a current collector and a negative electrode material layer located on the surface of the current collector; the negative electrode material layer comprises negative electrode active material particles, a conductive agent, a binder, and oxide solid electrolyte particles; and the oxide solid electrolyte particles are dispersed among the negative electrode active material particles. In the present invention, in a preparation process of the negative electrode plate, an oxide solid electrolyte dispersion is added, and the oxide solid electrolyte dispersion is dispersed among the negative electrode active material particles. The oxide solid electrolyte particles added into the negative electrode plate of the present invention are high in chemical stability and are directly mixed in the negative electrode active materials, so that the thermal stability of the negative electrode plate is improved without affecting electrochemical performance, the safety of the battery is guaranteed, and the current mainstream preparation processes of the negative electrode plate, a separator and the battery are not changed. The method is compatible with the mainstream preparation process of existing lithium ion battery negative electrode plates, and is suitable for large-scale application.

Description

A kind of negative electrode sheet for lithium battery and its preparation method and application

Cross-references to related applications

This application claims the rights and interests of Chinese patent application 202210246916.X submitted on March 14, 2022. The content of this application is incorporated herein by reference.

Technical field

The present invention relates to the technical field of lithium batteries, and in particular to a negative electrode sheet for lithium batteries and its preparation method and application.

Background technique

Lithium-ion batteries have the advantages of high energy density, good cycle performance, long service life, low self-discharge, and no memory effect. They have gradually occupied a larger application market in energy storage, power batteries, and 3C electronics, and have broad application prospects. .

As an important component of lithium-ion batteries, negative electrode materials are one of the main shortcomings that limit battery energy density, rate and other performance. At present, the main anode materials include lithium titanate anode materials, graphite anode materials, hard carbon, soft carbon anode materials, silicon carbon, silicon oxygen, silicon oxygen carbon composite anode materials, pure silicon anode materials, tin oxide and other metal oxide anode materials. . From the perspective of energy storage cost and cycle performance, hard carbon and soft carbon with good cycle performance and low cost have obvious advantages. Considering the cycle performance, volume energy density and rate performance of 3C electrons, graphite anode materials with good cycle performance and rate performance have obvious advantages. Considering the energy density of power batteries and the cruising range of electric vehicles, high-capacity silicon-carbon anode material systems have obvious advantages. Different anode materials have good application prospects in different segments.

Although different anode materials can match different application fields, there are still safety issues when using several anode materials in batteries, among which:

The safety problems of graphite materials are: when the battery is operating at a high charging rate, the battery polarization increases, reaching the lithium ion deposition overpotential, and lithium ions precipitate in the form of lithium dendrites on the surface of the graphite particles. Highly active lithium dendrites react violently with the electrolyte, inducing thermal runaway in the battery, and the heat release increases sharply during the thermal runaway process.

The safety problems of silicon-based materials (such as silicon-oxygen, silicon-carbon, silicon-oxycarbon and pure silicon materials) are: 1) Silicon is pulverized during the circulation process, forming a large number of nanoparticles, and the reaction of silicon particles with high specific surface area Higher activity, increasing the heat release when the battery thermal runaway; 2) Li-Si alloy in the charged state has high reactivity; 3) Due to the continuous volume changes of the silicon material, it is difficult to form a stable SEI film on the surface, which inhibits the thermal runaway of the battery The effect is worse.

At the same time, the safety performance of the battery is related to the interaction between the positive and negative electrodes: the charged positive electrode material releases oxygen in a high-temperature environment and diffuses to the negative electrode side, where a violent oxidation-reduction reaction occurs, releasing a large amount of heat, and ultimately leading to thermal runaway.

The above battery problems are all related to the negative side, resulting in poor battery safety performance. How to effectively solve the safety hazards on the negative electrode side and avoid thermal runaway of batteries has become an urgent problem that domestic and foreign companies need to solve.

Currently, methods to improve the safety of lithium batteries include modification of negative electrode materials, adding PTC coatings, insulation/flame retardant coatings, etc. For example, patent CN113233451A introduces a special method of modifying artificial graphite. The modified artificial graphite has a rich microporous structure. By improving the rate performance of the graphite material, it reduces the risk of lithium precipitation in the negative electrode and improves the safety performance of the battery. However, the porous modified artificial graphite prepared by this invention has a complicated process and cannot completely solve the problem of lithium precipitation caused by high rates, and the improvement in safety performance is limited.

Patent CN112952035A introduces a method for preparing silicon-oxygen materials that can improve battery safety performance. By coating the surface of silicon-oxygen materials with graphene, the powdering caused by the volume change of silicon-oxygen materials during the cycle is suppressed to improve battery safety. performance. However, the coating layer will gradually fall off as the cycle progresses, and there are still potential safety hazards during long cycles.

CN104409681A introduces a method for preparing PTC-coated lithium-ion battery pole pieces. It discloses a method of pre-coating a temperature-sensitive pre-coating on the current collector, and then coating the positive or negative active material. The pre-coating has good electrical conductivity at room temperature. When the temperature rises, the resistance rises sharply, preventing the battery from further heating, thus improving the safety of lithium-ion batteries. However, due to the instantaneous thermal runaway of acupuncture, the coating's mechanism of action often has no time to take effect and cannot effectively improve the safety of acupuncture.

In addition, the above-mentioned methods of coating ceramic separators, using PTC coatings, and building insulation or flame-retardant coatings will reduce the electrochemical performance of the battery. After using these methods, the overall performance of the battery core needs to be optimized; On the other hand, the material preparation process is complex, or it may have a certain impact on the electrode or battery core preparation process, making it difficult to produce on a large scale.

Therefore, it is still necessary to find a method with simple steps and cost advantages that can improve safety performance while ensuring the electrical performance of the battery.

Contents of the invention

In view of the limitations of the above-mentioned prior art, the present invention provides a negative electrode sheet for lithium batteries and its preparation method and application. In the present invention, specific oxide solid electrolyte particles are added during the preparation process of the negative electrode sheet, and are dispersed among the negative electrode active material particles to cooperate with the conductive agent and the binder. On the basis of not affecting the electrochemical performance, the invention improves the The thermal stability of the negative electrode ensures the safety of the battery.

One of the objects of the present invention is to provide a negative electrode sheet for lithium batteries. The negative electrode sheet includes a current collector and a negative electrode material layer located on the surface of the current collector. The negative electrode material layer includes negative electrode active material particles, conductive agent, adhesive, A binder, the negative electrode material layer further includes oxide solid electrolyte particles capable of conducting lithium ions; the oxide solid electrolyte particles in the negative electrode material layer are dispersed between the negative electrode active material particles;

The oxide solid electrolyte particles are selected from lithium-containing materials or a mixture of lithium-containing materials and aluminum phosphate;

The lithium-containing material includes compounds composed of lithium, hydrogen, aluminum, phosphorus, halogen and oxygen elements.

Preferably, the chemical formula of the lithium-containing material is Li _1+x H _1-x Al(PO ₄ )O _1-y M _2y , where 0≤x<1, 0<y<0.1, and M is a halogen element,

The M is preferably any one of F, Cl, Br or I; preferably the mass ratio of the lithium-containing material to AlPO ₄ is (1-4):1;

More preferably, the lithium-containing material is selected from at least one of LiHAl(PO ₄ )O _1-y M _2y , most preferably from LiHAl(PO ₄ )O _0.96 F _0.08 , LiHAl(PO ₄ )O _0.95 F _0.1 , LiHAl At least one of (PO ₄ )O _0.94 Cl _0.12 or LiHAl(PO ₄ )O _0.94 Br _0.12 ;

The crystal form of the aluminum phosphate is one or more of quartz type, tridymite type or cristobalite type.

Preferably, the preparation method of the lithium-containing material is:

Step (1) Weigh the lithium salt, aluminum-containing material, phosphorus-containing material and halogen-containing material according to the composition of the lithium-containing material, and mix them evenly to obtain a mixture;

Step (2): sintering the mixture and optionally pulverizing it to obtain a lithium-containing material.

Preferably, the lithium salt is selected from at least one of lithium carbonate, lithium hydroxide, lithium nitrate or lithium acetate;

The aluminum-containing material is selected from at least one of aluminum oxide, aluminum hydroxide or aluminum sulfate;

The phosphorus-containing material is selected from at least one of phosphorus pentoxide, phosphoric acid, phosphate or phosphine;

The halogen-containing material is selected from at least one selected from the group consisting of lithium hexafluorophosphate, hydrogen fluoride, phosphorus fluoride, phosphorus bromide, and phosphorus chloride.

Preferably, the lithium salt, aluminum-containing material, phosphorus-containing material and halogen-containing material are mixed and batched according to a molar ratio of Li, Al, P and halogen of 10-20:10-20:10-20:1;

In step (1), mixing is performed by stirring, preferably the mixing time is 10s to 30min, and the stirring rate is 200rpm to 2000rpm;

In step (2), the sintering temperature is 300°C to 1000°C, the sintering time is 5h to 256h; the sintering atmosphere is air atmosphere or inert gas atmosphere;

During the crushing process, first pour the semi-finished lithium-containing material into the crushing equipment for primary crushing treatment, and then put the primary crushing material into the crushing equipment for crushing to obtain a particle size D50 of 10nm-10μm; preferably 0.01-3μm; Lithium-containing materials of 0.05-0.5 μm are more preferred.

Preferably, during X-ray diffraction of the lithium-containing material prepared in the present invention, the measured 2θ angle has a characteristic diffraction peak at 15-35°.

Preferably, when the oxide solid electrolyte particles are a mixture of lithium-containing materials and aluminum phosphate, the preparation method of the oxide solid electrolyte particles is:

After the lithium-containing material and aluminum phosphate are mixed evenly, a mixed powder is obtained. The mixed powder is heat-treated under the protection of inert gas, cooled, and pulverized to prepare the material for improving battery safety.

The inert gas includes one or more of nitrogen, helium or argon;

The heat treatment conditions are to maintain the temperature at 100°C-1000°C for 1-20 hours, and preferably to increase to 100°C-1000°C at a rate of 1-20°C/min;

The cooling condition is to drop to room temperature at a rate of 1-20°C/min.

Preferably, when the lithium-containing material and aluminum phosphate are mixed uniformly, the mixing equipment used includes: a dual-motion mixer, a three-dimensional mixer, a V-shaped mixer, a single-cone double-spiral mixer, a trough-type ribbon mixer, or a horizontal vacuum mixer. A type of gravity mixer.

Preferably, the heat treatment equipment includes one of a box furnace, a tube furnace, a roller kiln, a push plate kiln or a rotary kiln.

Preferably, crushing equipment is used to finely crush the powder or lump mixed material obtained after heat treatment and cooling; the crushing equipment includes: jaw crusher, cone crusher, impact crusher, hammer crusher and roller crusher. Crushing, flat jet pulverizer, fluidized bed jet pulverizer, circulating jet pulverizer, impact crusher, expansion crusher, ball mill, high-speed rotating projectile pulverizer or high-speed rotating impact pulverizer one or several kinds.

In the present invention, the particle size of the negative electrode active material particles has no special requirements for the particle size of the negative electrode during use, and the existing conventional particle size range can be used;

Preferably, the particle diameter D50 of the oxide solid electrolyte particles is 10 nm-10 μm; preferably 0.01-3 μm; more preferably 0.05-0.5 μm.

The negative electrode material layer also includes a dispersant and a thickener;

In the present invention, the sum of each component in the negative electrode material layer is 100%. The specific content of each component can be adjusted according to conventional means and conventional content depending on the usage requirements; preferably, the weight of the negative electrode material layer is 100%. ,

The content of the negative active material particles is 80-99.5wt%, preferably 90-99.5wt%;

The content of the conductive agent is 0.1-8wt%, preferably 0.1-3.5wt%;

The content of the binder is 0.1-10wt%, preferably 0.1-5wt%;

The content of the oxide solid electrolyte particles is 0.1-10wt%, more preferably 0.2-5wt%;

Further optionally, the content of the dispersant is 0-1wt%, preferably 0.05-1wt%;

The content of the thickener is 0-1wt%, preferably 0.05-1wt%.

Preferably, the negative active material particles are selected from at least one of carbon materials, lithium-containing oxides, transition metal oxides, sulfides, metal alloys or silicon-containing materials; the carbon material is preferably selected from graphite, hard carbon, and soft carbon. , the lithium-containing material is preferably selected from Li ₄ Ti ₅ O ₁₂ and LiVO ₂ , the transition metal oxide is preferably selected from SnO, CoO, the sulfide is preferably selected from MoS ₂ , the metal alloy is preferably selected from tin alloy, and the silicon-containing material is preferably selected from silicon, SiOx, silicon At least one of carbon or silicon-oxycarbon; more preferably at least one of Li ₄ Ti ₅ O ₁₂ , graphite, hard carbon, soft carbon, SiOx, silicon-carbon, silicon-oxycarbon or silicon.

Preferably,

The dispersant is selected from at least one of sodium polyacrylate, ammonium polyacrylate copolymer, and polyvinyl alcohol;

The thickener is selected from at least one selected from sodium carboxymethyl cellulose, carboxyethyl cellulose, sodium alginate, polyacrylamide and polyvinyl alcohol;

In the present invention, the current collector can be any existing conventional current collector material, preferably copper foil or porous copper current collector;

The conductive agent can be any existing conventional conductive agent, preferably from Super-P, KS-6, carbon black, nano carbon fiber, carbon nano At least one of tube, acetylene black or graphene;

The binder is selected from the group consisting of sodium carboxymethyl cellulose, polyether modified silicone polymer (such as MS resin), styrene-butadiene rubber, nitrile rubber, butadiene rubber, modified styrene-butadiene rubber (such as sulfhydryl graft At least one of styrene-butadiene rubber), polyacrylic acid, polyacrylate (lithium polyacrylate, sodium polyacrylate, and their copolymers with acrylic acid), polyacrylate, polyacrylonitrile and acrylonitrile copolymer.

Among them, the conductive agent, binder, dispersant and thickener are not specifically limited in the present invention. The conductive agent, binder, dispersant and thickener mentioned in the present invention are all commonly used components in this field. , can be a commercially available product, or can be prepared according to known methods.

The second object of the present invention is to provide a method for preparing a negative electrode sheet for a lithium battery, which is one of the purposes of the present invention. During the preparation process of the negative electrode sheet, an oxide solid electrolyte dispersion is added and dispersed among the negative active material particles. ;

Preferably, the preparation method includes the following steps:

S1: Add the oxide solid electrolyte particles to water and grind them, optionally adding a dispersant and a thickener to prepare the first slurry;

S2: Mix the first slurry, negative active material particles, conductive agent, and binder evenly to prepare the second slurry;

S3: Apply the second slurry to the current collector, bake, roll, die-cut, and dry to obtain the negative electrode sheet;

In the present invention, the process conditions of baking, rolling, die-cutting and drying can adopt the existing conventional process conditions or the range adjusted by conventional processes. The preferred baking temperature is 75-110°C and the time is 1 minute. -1 hour, the rolling pressure is 5-100t, the vacuum drying temperature is 80-180°C, and the time is 3-100 hours.

Preferably, the mass ratio of water to oxide solid electrolyte particles in the first slurry is (2000-10): 100;

In step S2, the mass ratio of the oxide solid electrolyte particles and the negative active material particles in the first slurry is (0.1-10): (80-99.5).

The third object of the present invention is to provide the application of the negative electrode sheet for lithium batteries described in one of the objects of the present invention in lithium batteries, preferably in liquid lithium batteries or semi-solid lithium batteries.

The present invention improves the thermal stability of the negative electrode sheet without affecting the electrochemical performance by adding oxide solid electrolyte particles with a particle size D50 of 10 nm to 10 μm in the negative electrode sheet and cooperating with the conductive agent and binder. Ensure battery safety.

The technical principle is: first, the oxide solid electrolyte particles have a certain ion transmission capability, and can also effectively block the contact between the negative active material particles and improve the thermal stability while ensuring ion transmission; secondly , the oxide solid electrolyte itself has an endothermic effect, which can absorb part of the heat, alleviate the overheating of the negative electrode, and reduce the side reactions of the negative active material at high temperatures; thirdly, the halogen element in the material can participate in the formation of the electrode SEI to form Li-X (X=F, Cl, Br, I) such as LiF, improves the stability of the SEI on the surface of the pole piece, inhibits the reaction between the negative electrode and the electrolyte, and the reaction between the negative electrode and oxygen during thermal runaway, thus preventing the battery from being damaged before and after the thermal runaway process. can prevent the battery from further exothermic and improve the safety performance of the battery; finally, the doping of hydrogen changes the polarization properties and surface energy of the solid electrolyte material, making it compatible with the SEI produced by the decomposition of the existing electrolyte, and helps To generate a more stable SEI, thereby improving the interfacial stability of the solid electrolyte material.

Compared with the existing technology, the present invention has the following advantages and outstanding effects:

The oxide solid electrolyte particles added to the lithium battery negative electrode sheet of the present invention have low halogen content, the material synthesis is less difficult, and the segregation and uneven distribution of halogen elements are not prone to occur; and the material has a phosphate structure, which is better than existing materials. There are perovskite structure and garnet structure solid electrolytes, and phosphate structure solid electrolyte materials have better stability.

The oxide solid electrolyte particles added to the lithium battery negative electrode sheet of the present invention have high chemical stability and have a pH range of 6 to 9 after being dispersed in water. Adding them to the negative electrode slurry does not affect the mixing effect and does not change the current negative electrode sheet and separator. It is compatible with the mainstream preparation process of existing lithium-ion battery negative electrode sheets and does not affect the preparation process of positive electrodes and batteries. It has the advantages of high stability and low cost, and is suitable for large-scale applications.

Oxide solid electrolyte particles have a certain ion transmission capability, and can also effectively block the contact between negative active material particles and improve thermal stability while ensuring ion transmission; in contrast, if a barrier is used If the anode active particles are coated with burning substances and modified, the coating layer will hinder the ion and electron transmission of the anode active particles and affect the overall performance of the battery;

The oxide solid electrolyte particles added to the lithium battery negative electrode sheet of the present invention mainly contain elements such as lithium, aluminum, phosphorus, oxygen, halogen, etc., and do not contain Ti or Ge elements that are easily reduced in the negative electrode, and are more stable in the negative electrode. Existing common solid electrolytes such as LAGP (Li _1.5 Al _0.5 Ge _1.5 P ₃ O ₁₂ ), LLZO, LATP and other materials are prone to reduction reactions of metal ions at the negative electrode potential. In the present invention, the metal elements in the particles in the solid electrolyte are It is not easily reduced under low voltage, which improves the stability of the negative electrode.

The halogen element in the oxide solid electrolyte particles added to the lithium battery negative electrode sheet of the present invention can participate in the formation of the SEI of the negative electrode, such as forming LiF, which improves the stability of the SEI on the surface of the negative electrode particles and inhibits the reaction between the negative electrode and the electrolyte during thermal runaway. Thereby improving the safety performance of the battery.

Different from general solid electrolyte materials, the present invention innovatively uses hydrogen doping to change the polarization properties and surface energy of the solid electrolyte material, making it compatible with SEI generated by the decomposition of existing electrolytes, and helps To generate a more stable SEI, thereby improving the interfacial stability of the solid electrolyte material.

The lithium battery assembled based on the negative electrode sheet of the present invention can improve the safety characteristics of the battery without affecting the electrochemical performance. The battery can successfully pass the acupuncture test, and other safety performance test results are improved.

Description of the drawings

Figure 1 is an XRD pattern of the lithium-containing material prepared in Example 1 of the present invention;

Figure 2 is the micromorphology and F element distribution diagram of the lithium-containing material prepared in Example 1 of the present invention;

Figure 3 is an XRD pattern of the lithium-containing material prepared in Example 2 of the present invention;

Figure 4 is an XRD pattern of the lithium-containing material prepared in Example 4 of the present invention;

Figure 5 is an XRD pattern of the lithium-containing material prepared in Example 5 of the present invention;

Figure 6 is a schematic structural diagram of the negative electrode sheet for lithium batteries of the present invention.

Explanation of reference symbols:

1-negative active material particles, 2-oxide solid electrolyte particles, 3-current collector.

Detailed ways

The present invention will be described in detail below with reference to specific examples. It is necessary to point out here that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the protection scope of the present invention. Those skilled in the art will make reference to the present invention based on the content of the present invention. Some non-essential improvements and adjustments made by the invention still fall within the protection scope of the invention.

Lithium battery electrochemical performance testing method:

1. Capacity and energy density testing

a) Weigh the battery weight and record it;

b) At 23±2°C, the battery is discharged at a constant current of 0.33C until it reaches the discharge termination voltage and left to stand for 1 hour;

c) Charge at a constant current of 0.33C until the charging end voltage is reached, then switch to constant voltage charging until the charging current rate drops to 0.05C, stop charging, and let it sit for 1 hour;

d) The battery is discharged at a constant current of 0.33C until it reaches the discharge termination voltage and stops discharging;

e) Record the discharge capacity (Ah) and discharge energy, divide the discharge energy by the mass, and obtain the energy density (Wh/Kg);

f) Repeat steps c)-e) 5 times. When the range of the three consecutive test results is less than 3%, the test can be terminated early and the average of the last three test results will be taken.

Note: Range refers to the difference between the maximum value and the minimum value of the test result;

2.Cycle performance test

a) At 23℃±2℃, charge with 1C constant current until the charging end voltage is reached, then switch to constant voltage charging until the charging current rate drops to 0.05C, stop charging, and let it stand for 1 hour;

b) The battery is discharged at a constant current of 1C until it reaches the discharge termination voltage, stops discharging, and records the discharge capacity; thus completing a cycle;

c) Repeat steps a and b until the discharge capacity is lower than 80% of the discharge capacity in the first week, and record the total number of battery cycles at this time.

3. Magnification test

a) At 23°C ± 2°C, the battery is charged at 0.1C, 0.2C, 0.33C, 1C, 2C, and 3C rates to the charge end voltage and then discharged to the discharge end voltage at the same rate. The same rate is cycled 4 times. ;

b) Record the discharge capacity at different rates;

c) Calculate the ratio of 3C discharge capacity to 0.33C discharge capacity, recorded as 3C/0.33C, and evaluate the rate performance.

4. High temperature cycle

a) Charge at 45°C with a constant current of 1C until the charging termination voltage is reached, then switch to constant voltage charging until the charging current rate drops to 0.05C, then stop charging;

b) The battery is left standing at 45°C for 5 hours;

c) Under high temperature conditions of 45°C, the battery is discharged at a constant current of 1C until it reaches the discharge end voltage, stops discharging, and records the discharge Capacity; this completes a cycle;

d) Repeat steps a to c until the discharge capacity is lower than 80% of the discharge capacity in the first week. Record the discharge capacity of the battery and the total number of cycles at this time.

Lithium battery safety performance testing method:

1. Overcharging

a) At 23℃±2℃, charge with 1C constant current until the charging end voltage is reached, then switch to constant voltage charging until the charging current rate drops to 0.05C, stop charging, and let it stand for 1 hour;

b) Continue charging at a constant current of 1C until the battery undergoes thermal runaway, and record the voltage value of the battery when thermal runaway begins.

2.Hot box

a) At 23℃±2℃, charge at 1C constant current until the charging end voltage is reached, then switch to constant voltage charging until the charging current rate drops to 0.05C, stop charging, and let it stand for 1 hour;

b) Put the battery into the test box. The test box heats up at a temperature rise rate of 5°C/min. When the temperature inside the box reaches 160°C ± 2°C, it is kept at a constant temperature for 1 hour;

The battery passes if it does not smoke, catch fire or explode, otherwise it fails.

3. fall

a) At 23℃±2℃, charge at 1C constant current until the charging end voltage is reached, then switch to constant voltage charging until the charging current rate drops to 0.05C, stop charging, and let it stand for 1 hour;

b) Drop the body freely onto the concrete slab from a drop height of 1m; drop each side of the soft-packed battery once, and conduct a total of six tests; after six tests, the battery will pass if it does not smoke, catch fire, or explode. Otherwise it will not pass.

4. Impact of heavy objects

a) At 23℃±2℃, charge at 1C constant current until the charging end voltage is reached, then switch to constant voltage charging until the charging current rate drops to 0.05C, stop charging, and let it stand for 1 hour;

b) Place the battery on the surface of the platform, place a metal rod with a diameter of 15.8mm±0.2mm horizontally on the upper surface of the geometric center of the battery, and use a weight with a mass of 9.1kg±0.1kg to fall freely from a height of 610mm±25mm. Impact the battery surface with a metal rod and observe for 6 hours. If the battery does not smoke, fire or explode, it will pass, otherwise it will not pass.

5.Acupuncture

a) At 23℃±2℃, charge at 1C constant current until the charging end voltage is reached, then switch to constant voltage charging until the charging current rate drops to 0.05C, stop charging, and let it stand for 1 hour;

b) use A high-temperature resistant steel needle (the cone angle of the needle tip is 45°, the surface of the needle is smooth, free of rust, oxide layer and oil stain), penetrates from the direction perpendicular to the battery plate at a speed of 25mm/s, and the penetration position is the pierced position. At the geometric center of the surface, the steel needle stays in the battery;

c) Observe for 1 hour; if the battery does not smoke, fire or explode, it will pass, otherwise it will not pass.

Example 1

A method for preparing a negative electrode sheet for a lithium battery. Based on the weight of the negative electrode material layer being 100wt%, the content of the negative active material particles is 95.8wt%; the content of the conductive agent is 1wt%; and the content of the binder is 100wt%. 1wt%; the content of the oxide solid electrolyte particles is 2wt%, the content of the dispersant is 0.1wt%; the content of the thickening agent is 0.1wt%. Calculate and add the above substances accordingly (in the invention, the negative active material particles , conductive agents, binders, oxide solid electrolyte particles, dispersants and thickeners are relatively stable during the preparation process and there is basically no loss), the details are as follows:

S1: Grind the oxide solid electrolyte particles LiHAl(PO ₄ )O _0.95 F _0.1 with deionized water until the particle size D50 is 300 nm, add the dispersant sodium polyacrylate and the thickener sodium carboxymethylcellulose to prepare Uniform first slurry; the mass ratio of water and oxide solid electrolyte particles is 1000:100;

S2: Mix the first slurry, negative active material particle graphite, conductive agent Super P, binder styrene-butadiene rubber SBR and carboxymethyl cellulose CMC evenly to prepare the second slurry;

S3: Apply the second slurry to the current collector copper foil, bake, roll, and die-cut to obtain a negative electrode sheet with a negative electrode material layer thickness of 100um. The negative electrode sheet is vacuum dried at 120°C for 24 hours to obtain the final Negative plate.

The negative electrode sheet for lithium batteries prepared by the above method includes a current collector 3 and a negative electrode material layer located on the surface of the current collector; the negative electrode material layer includes negative electrode active material particles 1, a conductive agent, a binder and an oxide solid capable of conducting lithium ions. Electrolyte particles 2, dispersant and thickener; the oxide solid electrolyte particles 2 in the negative electrode material layer are dispersed between the negative electrode active material particles 1, as shown in Figure 6.

Preparation of positive electrode sheet:

Mix the positive active material particles lithium iron phosphate, conductive agent Super P, conductive agent CNT, and binder PVDF evenly to obtain a slurry;

The above slurry is applied to the current collector aluminum foil, and after baking, rolling and die-cutting, a positive electrode sheet is obtained. The positive electrode sheet is vacuum dried at 120°C for 24 hours to obtain a positive electrode sheet for lithium batteries.

Among them, when preparing the above-mentioned positive electrode sheet for lithium batteries, the weight of the positive electrode material layer is 100wt%, the content of the positive electrode active material particles is 95.8wt%; the content of the conductive agent SP is 1wt%; the content of the conductive agent CNT is 0.2wt %; the content of the binder is calculated as 3wt% and the above substances are added accordingly.

The negative electrode sheet for lithium batteries prepared by the above method is matched with the prepared lithium iron phosphate positive electrode sheet and separator. The positive and negative electrode sheets are stacked, the tabs are welded, the aluminum plastic film is packaged, and the electrolyte (EC, EMC) is injected. and DMC as the solvent and lithium hexafluorophosphate as the lithium salt), top side sealing, forming two seals and dividing the volume, and then assembled into a soft-packed lithium battery. The soft-packed lithium battery prepared above was subjected to electrochemical and safety tests. The specific electrochemical The performance test results are shown in Table 1, and the safety performance test results are shown in Table 2.

The preparation method of lithium-containing material LiHAl(PO ₄ )O _0.95 F _0.1 is as follows:

Step (1) Stir and mix lithium salt lithium hydroxide, aluminum-containing material aluminum hydroxide, phosphorus-containing material phosphoric acid and halogen-containing material hydrogen fluoride. The mixture is uniform, the molar ratio of Li, Al, P, and halogen is 10:10:10:1, the mixing time is 10min, and the stirring rate is 500rpm; a mixture is obtained;

Step (2) Sintering the mixture, the sintering temperature is 1000°C, the sintering time is 5 hours; the sintering atmosphere is air atmosphere, to obtain a semi-finished lithium-containing material, and then first pour the semi-finished lithium-containing material into the crushing equipment. Primary crushing treatment, and then the materials after primary crushing treatment are put into the crushing equipment for crushing. After the crushing process, lithium-containing materials with a particle size of 3 μm are obtained.

The lithium-containing material prepared by the above method includes hydrogen, aluminum, phosphorus, halogen and oxygen elements, and the chemical formula is LiHAl(PO ₄ )O _0.95 F _0.1 ; during X-ray diffraction of the lithium-containing material, the measured 2θ angle is at 15 There is a characteristic diffraction peak at -35°, and the corresponding XRD is shown in Figure 1; the F element of the lithium-containing material is evenly distributed on the particles without segregation, and the corresponding morphology and F element distribution test results are shown in Figure 2 .

Example 2

The same preparation method and material addition amount were used as in Example 1, except that the oxide solid electrolyte material used was LiHAl(PO ₄ )O _0.96 F _0.08 , the dispersant material was polyvinyl alcohol, and the thickener material was alginic acid. Sodium; the positive active material particles in the battery system used are lithium cobalt oxide, and the negative active material particles in the negative electrode sheet are graphite. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2 .

The preparation method of lithium-containing material LiHAl(PO ₄ )O _0.96 F _0.08 is as follows:

Step (1) Stir and mix the lithium salt lithium carbonate, the aluminum-containing material alumina, the phosphorus-containing material phosphorus pentoxide, and the halogen-containing material hydrogen fluoride, where the molar ratio of Li, Al, P, and halogen is 12.5:12.5:12.5: 1. The mixing time is 30 minutes and the stirring rate is 200 rpm; the mixture is obtained;

Step (2) Sintering the mixture, the sintering temperature is 300°C, the sintering time is 200h; the sintering atmosphere is a nitrogen atmosphere, to obtain a semi-finished lithium-containing material, and then first pour the semi-finished lithium-containing material into the crushing equipment. Primary crushing treatment, and then the materials after the primary crushing treatment are put into the crushing equipment for crushing. After the crushing process, lithium-containing materials with a particle size of 5 μm are obtained.

The lithium-containing material prepared by the above method includes hydrogen, aluminum, phosphorus, halogen and oxygen elements, and the chemical formula is LiHAl(PO ₄ )O _0.96 F _0.08 ; during X-ray diffraction of the lithium-containing material, the measured 2θ angle is 15 There is a characteristic diffraction peak at -35°, and the corresponding XRD is shown in Figure 3.

Example 3

The same preparation method and material addition amount are used as in Example 1. The difference is: the oxide solid electrolyte material used is LiHAl(PO ₄ )O _0.95 F _0.1 and AlPO ₄ mixed with a mass ratio of 2:1, and the rest is the same as in Example 1 Similarly, the specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2.

The solid electrolyte material is a mixture of LiHAl(PO ₄ )O _0.95 F _0.1 and AlPO _4. The preparation method is as follows:

Aluminum phosphate (quartz type) with a particle size of 30 μm and the lithium-containing material prepared in Example 1, (LiHAl(PO ₄ )O _0.95 F _0.1 ) Mix evenly in a V-type mixer at a mass ratio of 2:1, then put the mixed materials in a tube furnace under the protection of nitrogen atmosphere, raise the temperature to 600°C at 2°C/min and keep it for 10 hours, and then heat it at 10°C /min to cool down to room temperature. Then, the heat-treated material is first crushed into small pieces by a cone crusher, and then crushed into 3 μm-sized powder by a flat jet pulverizer to obtain a mixture of LiHAl(PO ₄ )O _0.95 F _0.1 and AlPO ₄ .

Example 4

The same preparation method and material addition amount were used as in Example 1, except that the positive active material in the battery system used was NCM811, and the negative active material particles in the negative electrode sheet were graphite. The specific electrochemical performance test of the prepared lithium battery The results are shown in Table 1, and the safety performance test results are shown in Table 2.

Example 5

The same preparation method and material addition amount were used as in Example 1, except that the oxide solid electrolyte material used was LiHAl(PO ₄ )O _0.94 Cl _0.12 and AlPO ₄ mixed with a mass ratio of 2:1, and the dispersant material was poly Sodium acrylate, the thickener material is polyacrylamide, the positive active material particles in the battery system used are NCM811, and the negative active material particles in the negative electrode sheet are SiOC450. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1 , the safety performance test results are shown in Table 2.

The preparation of lithium-containing materials includes the following steps:

Step (1) Stir and mix the lithium salt lithium acetate, the aluminum-containing material aluminum hydroxide, the phosphorus-containing material phosphine and the halogen-containing material phosphorus chloride. The molar ratio of Li, Al, P, and halogen is 16.6:16.6: 16.6:1, the mixing time is 1min, the stirring rate is 1800rpm; a mixture is obtained;

Step (2) Sintering the mixture, the sintering temperature is 500°C, the sintering time is 100h; the sintering atmosphere is a nitrogen atmosphere, to obtain a semi-finished lithium-containing material, and then first pour the semi-finished lithium-containing material into the crushing equipment. Primary crushing treatment, and then the materials after primary crushing treatment are put into the crushing equipment for crushing. After the crushing process, lithium-containing materials with a particle size of 10 μm are obtained.

The lithium-containing material prepared by the above method includes hydrogen, aluminum, phosphorus, halogen and oxygen elements, and the chemical formula is LiHAl(PO ₄ )O _0.94 Cl _0.12 ; during X-ray diffraction of the lithium-containing material, the measured 2θ angle is at 15 There is a characteristic diffraction peak at -35°, and the corresponding XRD is shown in Figure 4.

Mix aluminum phosphate (cristobalite type) with a particle size of 3 μm and lithium-containing material (LiHAl(PO ₄ )O _0.94 Cl _0.12 ) with a particle size of 10 μm in a trough ribbon mixer at a mass ratio of 2:1. The mixed materials were then heated to 500°C in a rotary kiln under nitrogen atmosphere protection at a rate of 6°C/min and kept for 15 hours, and then cooled to room temperature at a rate of 8°C/min. The heat-treated material is then crushed into small pieces by a roller crusher, and then crushed into 4.5 μm-sized powder by a fluidized bed jet pulverizer to obtain oxide solid electrolyte particles.

Example 6

The same preparation method and material addition amount are used as in Example 1. The difference is: the oxide solid electrolyte material used is LiHAl(PO ₄ )O _0.94 Br _0.12 and AlPO _4. The mass ratio is 1.5:1, and the dispersant material used It is polyvinyl alcohol and the thickener is seaweed. sodium phosphate, the battery system used is: the positive active material particles are lithium iron phosphate, and the negative active material particles in the negative electrode sheet are pure silicon. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 1. Table 2.

The preparation method of the mixture of LiHAl(PO ₄ )O _0.94 Br _0.12 and AlPO ₄ is as follows:

The preparation of lithium-containing materials includes the following steps:

Step (1) Stir and mix the lithium salt lithium acetate, aluminum-containing material aluminum hydroxide, phosphorus-containing material phosphine and halogen-containing material phosphorus bromide evenly, where the molar ratio of Li, Al, P and halogen is 16.6:16.6: 16.6:1, the mixing time is 10min, the stirring rate is 1000rpm; a mixture is obtained;

Step (2) Sintering the mixture, the sintering temperature is 800°C, the sintering time is 50 hours; the sintering atmosphere is a nitrogen atmosphere, to obtain a semi-finished lithium-containing material, and then first pour the semi-finished lithium-containing material into the crushing equipment. Primary crushing treatment, and then the materials after primary crushing treatment are put into the crushing equipment for crushing. After the crushing process, lithium-containing materials with a particle size of 20 μm are obtained.

The lithium-containing material prepared by the above method includes hydrogen, aluminum, phosphorus, halogen and oxygen elements, and the chemical formula is LiHAl(PO ₄ )O _0.94 Br _0.12 ; during X-ray diffraction of the lithium-containing material, the measured 2θ angle is 15 There is a characteristic diffraction peak at -35°, and the corresponding XRD is shown in Figure 5.

Mix aluminum phosphate (cristobalite type) with a particle size of 5 μm and lithium-containing material (LiHAl(PO ₄ )O _0.94 Br _0.12 ) with a particle size of 20 μm in a trough ribbon mixer at a mass ratio of 1.5:1. Then, the mixed materials were heated to 1000°C in a rotary kiln under the protection of nitrogen atmosphere at 15°C/min and kept for 1 hour, and then cooled to room temperature at 1°C/min. The heat-treated material is then crushed into small pieces by a roller crusher, and then crushed into 900nm-sized powder by a fluidized bed jet pulverizer to obtain oxide solid electrolyte particles.

Example 7

The same preparation method and material addition amount are used as in Example 1. The difference is: the D50 of the sand-ground oxide solid electrolyte material used is 50nm. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1. Safety performance test The results are shown in Table 2.

Example 8

The same preparation method and material addition amount are used as in Example 1. The difference is: the D50 of the sand-ground oxide solid electrolyte material used is 500nm. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1. Safety performance test The results are shown in Table 2.

Example 9

The same preparation method as in Example 1 is used, except that the added amounts of each material are different, specifically:

Based on the weight of the negative electrode material layer being 100%, the content of the negative active material particles is 93.8wt%; the content of the conductive agent is 2wt%; the content of the binder is 2wt%; and the content of the oxide solid electrolyte particles The content of dispersant is 1wt%; the content of thickener is 1wt%; the specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2.

Example 10

The same preparation method as in Example 1 is used, except that the added amounts of each material are different, specifically:

Based on the weight of the negative electrode material layer being 100%, the content of the negative active material particles is 93wt%; the content of the conductive agent is 0.5wt%; the content of the binder is 0.5wt%; the oxide solid electrolyte particles are The content is 5wt%; the dispersant content is 0.5wt%; the thickener content is 0.5wt%; the specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2.

Comparative example 1

The same preparation method as in Example 1 is used, except that no oxide solid electrolyte material is added. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2.

Comparative example 2

The same preparation method as in Example 2 is used, except that no oxide solid electrolyte material is added. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2.

Comparative example 3

The same preparation method as in Example 4 is used, except that no oxide solid electrolyte material is added. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2.

Comparative example 4

The same preparation method as in Example 5 is used, except that no oxide solid electrolyte material is added. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2.

Comparative example 5

The same preparation method as in Example 6 is used, except that no oxide solid electrolyte material is added. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2.

Comparative example 6

The same preparation method as in Example 1 is adopted, except that aluminum oxide is used instead of the oxide solid electrolyte material. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2.

Comparative example 7

The same preparation method as in Example 2 is used, with the difference that LATP (Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ ) is used instead of the oxide solid electrolyte material. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1. The safety performance test results are shown in Table 2.

Comparative example 8

The same preparation method as in Example 4 is used, with the difference that LLTO (La _0.57 Li _0.29 TiO ₃ ) is used instead of the oxide solid electrolyte material. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 1. Table 2.

Comparative example 9

The same preparation method as in Example 5 is used, with the difference that LLZO (Li ₇ La ₃ Zr ₂ O ₁₂ ) is used instead of the oxide solid electrolyte material. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1. Safety performance test The results are shown in Table 2.

Comparative example 10

The same preparation method as in Example 6 is used, except that 15 wt% F-doped LLZO is used instead of the oxide solid electrolyte material. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2. .

Comparative example 11

The same preparation method as in Example 1 is used, with the difference that LiOF ₃ is used instead of the oxide solid electrolyte material. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2.

Comparative example 12

The same preparation method as in Example 1 is used, with the difference that AlPO ₄ is used instead of the oxide solid electrolyte material. The specific electrochemical performance test results of the prepared lithium battery are shown in Table 1, and the safety performance test results are shown in Table 2.

Table 1 shows the electrochemical performance data of lithium batteries prepared in the embodiments or comparative examples of the present invention, as follows:

Table 1

It can be seen from the results in Table 1 that when the battery system and battery capacity are the same, such as Example 1 and Example 3, Example 7, Example 8, Example 9, Example 10, Comparative Example 1, Comparative Example 6, Comparative Examples 11 and 12; Example 2 and Comparative Examples 2 and 7; Example 4 and Comparative Examples 3 and 8; Example 5 and Comparative Examples 4 and 9; Example 6 and Comparative Examples 5. Comparative Example 10; wherein: after adding the oxide solid electrolyte materials with different contents and different particle sizes in the present invention, there is no obvious impact on the battery performance.

Table 2 shows the safety performance data of lithium batteries prepared in the embodiments or comparative examples of the present invention, as follows:

Table 2

It can be seen from the results in Table 2 that there are several groups of Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, Example 4 and Comparative Example 3, Example 5 and Comparative Example 4, and Example 6 and Comparative Example 5. Data comparison shows that the use of the inorganic oxide solid electrolyte of the present invention can improve the battery's safety performance in hot box, heavy impact, drop, needle puncture and overcharge. Comparison between Example 1 and Comparative Example 6 shows that the use of the inorganic oxide solid electrolyte of the present invention has better safety performance than conventional alumina ceramic addition. The comparison between Example 2 and Comparative Example 7, Example 4 and Comparative Example 8, and Example 5 and Comparative Example 9 illustrates that the use of the inorganic oxide solid electrolyte of the present invention has better safety than conventional inorganic oxide solid electrolyte addition. Performance improvements. A comparison between Example 6 and Comparative Example 10 shows that the inorganic oxide solid electrolyte containing a small amount of halogen in the present invention has better safety performance than the conventional inorganic oxide solid electrolyte doped with halogen. A comparison between Example 1 and Comparative Example 11 shows that the inorganic oxide solid electrolyte of the present invention has better safety performance compared with the inorganic oxide solid electrolyte with high F content. The comparison between Example 1 and Example 3, and the greater improvement in safety performance between Example 5 and Example 6 compared to Comparative Example 4 and Comparative Example 5 respectively shows that when the inorganic oxide solid electrolyte of the present invention is used and contains aluminum phosphate, The improvement effect on safety performance is more obvious. Comparing Example 1, Comparative Example 1 and Comparative Example 12 shows that only adding lithium phosphate to the negative electrode sheet cannot achieve the effect of improving battery safety performance. implement Example 7, Example 8, Example 9 and Example 10 illustrate that the effect of improving safety performance can also be achieved when the particle size and addition amount are within the other ranges of the claims.

It can be understood that the above embodiments are only exemplary embodiments adopted to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims (10)

1. A negative electrode sheet for lithium batteries. The negative electrode sheet includes a current collector and a negative electrode material layer located on the surface of the current collector. The negative electrode material layer includes negative electrode active material particles, a conductive agent, and a binder, and is characterized by:

   The negative electrode material layer also includes oxide solid electrolyte particles;

   The oxide solid electrolyte particles in the negative electrode material layer are dispersed between the negative electrode active material particles;

   The oxide solid electrolyte particles are selected from lithium-containing materials or a mixture of lithium-containing materials and aluminum phosphate;

   The lithium-containing material includes compounds composed of lithium, hydrogen, aluminum, phosphorus, halogen and oxygen elements.
2. The negative electrode sheet for lithium batteries according to claim 1, characterized in that:

   The chemical formula of the lithium-containing material is Li _1+x H _1-x Al(PO ₄ )O _1-y M _2y , where 0≤x<1, 0<y<0.1, M is a halogen element,

   The M is preferably any one of F, Cl, Br or I;

   Preferably, the mass ratio of the lithium-containing material and AlPO ₄ is (1-4):1;

   More preferably, the lithium-containing material is selected from at least one of LiHAl(PO ₄ )O _1-y M _2y , most preferably from LiHAl(PO ₄ )O _0.96 F _0.08 , LiHAl(PO ₄ )O _0.95 F _0.1 , LiHAl At least one of (PO ₄ )O _0.94 Cl _0.12 or LiHAl(PO ₄ )O _0.94 Br _0.12 ;

   The crystal form of the aluminum phosphate is one or more of quartz type, tridymite type or cristobalite type.
3. The negative electrode sheet for lithium batteries according to claim 1, characterized in that:

   The particle diameter D50 of the oxide solid electrolyte particles is 10 nm-10 μm; preferably 0.01-3 μm; more preferably 0.05-0.5 μm.
4. The negative electrode sheet for lithium batteries according to claim 1, characterized in that:

   The mass percentage of the oxide solid electrolyte particles in the negative electrode material layer is 0.1-10wt%, preferably 0.2-5wt%.
5. The negative electrode sheet for lithium batteries according to claim 1, characterized in that:

   The negative electrode material layer also includes a dispersant and a thickener;

   Based on 100% of the weight of the negative electrode material layer,

   The content of the negative active material particles is 80-99.5wt%;

   The content of the conductive agent is 0.1-8wt%;

   The content of the binder is 0.1-10wt%;

   The content of the oxide solid electrolyte particles is 0.1-10wt%, more preferably 0.2-5wt%;

   Preferably,

   The content of the dispersant is 0-1wt%;

   The content of the thickener is 0-1wt%.
6. The negative electrode sheet for lithium batteries according to claim 1, characterized in that:

   The negative active material particles are selected from at least one of carbon materials, lithium-containing oxides, transition metal oxides, sulfides, metal alloys or silicon-containing materials; the carbon material is preferably selected from graphite, hard carbon, soft carbon, lithium-containing The oxide is preferably selected from Li ₄ Ti ₅ O ₁₂ and LiVO ₂ , the transition metal oxide is preferably selected from SnO and CoO, the sulfide is preferably selected from MoS ₂ , the metal alloy is preferably selected from tin alloy, and the silicon-containing material is preferably selected from silicon, At least one of SiOx, silicon carbon or silicon oxycarbon; more preferably at least one of Li ₄ Ti ₅ O ₁₂ , graphite, hard carbon, soft carbon, SiOx, silicon carbon, silicon oxycarbon or silicon.
7. The negative electrode sheet for lithium batteries according to claim 1, characterized in that:

   The dispersant is selected from at least one of sodium polyacrylate, ammonium polyacrylate copolymer or polyvinyl alcohol;

   The thickening agent is selected from at least one selected from sodium carboxymethyl cellulose, carboxyethyl cellulose, sodium alginate, polyacrylamide and polyvinyl alcohol.
8. The preparation method of the negative electrode sheet for lithium batteries according to any one of claims 1 to 7, characterized in that the preparation method includes the following steps:

   S1: Add the oxide solid electrolyte particles to water and grind them, optionally adding a dispersant and a thickener to prepare the first slurry;

   S2: Mix the first slurry, negative active material particles, conductive agent, and binder evenly to prepare the second slurry;

   S3: Apply the second slurry to the current collector, bake, roll, die-cut, and dry to obtain the negative electrode sheet.
9. The method for preparing negative electrode sheets for lithium batteries according to claim 8, characterized in that:

   In step S2,

   The mass ratio of the oxide solid electrolyte particles and the negative active material particles in the first slurry is (0.1-10): (99.5:80).
10. The application of the negative electrode sheet for lithium batteries according to any one of claims 1 to 7 in lithium batteries is preferably used in liquid lithium batteries or semi-solid lithium batteries.