A lithium-filled battery electrode assembly and its preparation method, and a lithium-filled battery.

Abstract

This invention discloses a lithium-filled battery electrode assembly, comprising a positive electrode, a negative electrode, and a separator. The battery electrode assembly is prepared by winding or stacking the positive electrode, negative electrode, and separator. The negative electrode includes a copper foil current collector, a negative electrode active material layer, lithium-filled cells, and a protective layer. A layer of negative electrode active material is coated on both the upper and lower surfaces of the copper foil current collector. Multiple lithium-filled cells are uniformly adhered to the side of each negative electrode active material layer away from the copper foil current collector. A protective layer is sprayed onto the exposed surface of each negative electrode active material layer and each lithium-filled cell. The lithium-filled cell is a lithium metal monomer of a predetermined shape. The separator has multiple bonding units on the side facing the positive electrode. This invention also discloses a method for preparing a lithium-filled battery electrode assembly and a lithium-filled battery. This invention is scientifically designed and can effectively improve the energy density of the battery while ensuring a long cycle life.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a lithium-filled battery electrode assembly and its preparation method, and a lithium-filled battery. Background Technology

[0002] Currently, lithium-ion batteries are widely used in digital products, electric vehicles, and energy storage due to their advantages such as high energy density, good cycle performance, and being environmentally friendly and pollution-free. With the widespread acceptance of lithium batteries, the demand for them continues to increase: longer range, lower price per unit mileage, longer lifespan, and safety.

[0003] From the perspective of lithium-ion battery development, energy density and long cycle life are the two most difficult indicators to achieve. On the one hand, it requires simultaneous progress in materials and processes; on the other hand, it requires a deep understanding of the entire chemical system, from electrolytes to main materials, from structure to failure mechanisms, and then technological improvements.

[0004] However, there is currently no lithium-ion battery that can effectively increase energy density and guarantee a long cycle life. Summary of the Invention

[0005] The purpose of this invention is to address the technical deficiencies of existing technologies by providing a lithium-filled battery electrode assembly and its preparation method, as well as a lithium-filled battery.

[0006] Therefore, the present invention provides a lithium-filled battery electrode assembly, comprising a positive electrode, a negative electrode, and a separator;

[0007] The separator is located between the positive and negative electrode plates;

[0008] A battery electrode assembly is an electrode assembly prepared by winding or stacking positive electrode sheets, negative electrode sheets, and a separator.

[0009] The negative electrode sheet includes a copper foil current collector, a negative electrode active material layer, a lithium replenishment unit, and a protective layer;

[0010] The upper and lower surfaces of the copper foil current collector are coated with a layer of negative electrode active material.

[0011] Each layer of negative electrode active material has multiple lithium replenishment units uniformly adhered on the side away from the copper foil current collector.

[0012] A protective layer is sprayed onto the exposed surface of each negative electrode active material layer and each lithium replenishment unit.

[0013] The lithium replenishment unit is a lithium metal monomer of a predetermined shape;

[0014] The diaphragm may be a first diaphragm or a second diaphragm;

[0015] The first separator specifically includes a base membrane, a ceramic layer, and bonding units, and a ceramic layer is disposed on the side of the base membrane facing the positive electrode; multiple bonding units are disposed on the ceramic layer;

[0016] The second separator specifically includes a base membrane and bonding units, with multiple bonding units disposed on the side of the base membrane facing the positive electrode sheet;

[0017] In the battery electrode assembly, multiple bonding units on the ceramic layer of the first separator or multiple bonding units on the base film of the second separator are arranged alternately with multiple lithium replenishment units on the negative electrode active material layer.

[0018] Preferably, the thickness of the lithium replenishment unit is 100 nm to 20 μm;

[0019] The length of the lithium replenishment unit is 1mm to 20cm;

[0020] The thickness of the protective layer ranges from 0.5 nm to 23 μm.

[0021] Preferably, when the upper and lower surfaces of the copper foil current collector are coated with a layer of negative electrode active material, the multiple lithium replenishment units on the two layers of negative electrode active material are arranged in an alternating manner.

[0022] Preferably, the protective layer is an insulating organic film.

[0023] In addition, the present invention also provides a lithium-filled battery, including the lithium-filled battery electrode assembly described above.

[0024] In addition, the present invention also provides a method for preparing a lithium-filled battery, comprising the following steps:

[0025] Step S1, preparation of the negative electrode sheet;

[0026] Step S2, preparation of the diaphragm;

[0027] Step S3, Preparation of positive electrode sheet: The positive electrode active material, conductive agent and binder are mixed evenly according to the preset mass ratio, and then dispersed in a solvent to prepare a positive electrode active material slurry. The positive electrode active material slurry is then evenly coated on the surface of the aluminum foil current collector, and then dried and rolled in sequence to obtain the positive electrode sheet.

[0028] Step S4, Preparation of battery electrode assembly: The positive electrode sheet, separator and negative electrode sheet cut according to the preset specifications are prepared into a battery electrode assembly by winding or stacking.

[0029] Specifically, step S1 includes the following sub-steps:

[0030] Step S11: Mix at least two negative electrode active materials evenly, then disperse them in a solvent, and then add a conductive agent, a dispersant, and a binder in sequence, and continue stirring to form a negative electrode active material slurry.

[0031] Step S12: The negative electrode active material slurry is uniformly attached to the copper foil current collector by spraying, and then the negative electrode sheet is obtained by drying and rolling processes.

[0032] Step S13: Multiple lithium replenishment units are uniformly disposed on the surface of the negative electrode active material layer of the unlithiated negative electrode sheet obtained in step S12. Then, a protective layer solution is uniformly sprayed onto the surface of the negative electrode active material layer and the lithium replenishment units. After drying, the finished negative electrode sheet is obtained.

[0033] Preferably, the lithium replenishment unit is a lithium metal monomer of a predetermined shape;

[0034] The thickness of the lithium replenishment unit is 100nm~20um;

[0035] The length of the lithium replenishment unit is 1mm to 20cm.

[0036] Preferably, step S2 specifically includes step S21 or step S22:

[0037] Step S21: Mix and stir the ceramic additive, binder and dispersant evenly to obtain a ceramic layer slurry. Then, coat the ceramic layer slurry onto the side of the base film facing the positive electrode and dry it to obtain a base film with a ceramic layer. Then, spray multiple bonding unit adhesive liquids onto the ceramic layer and dry it to form bonding units on the ceramic layer.

[0038] Step S22: Spray multiple bonding unit adhesives onto the side of the base film facing the positive electrode, and then dry it to form bonding units on the base film.

[0039] In steps S21 and S22, the bonding unit is a coagulated colloid of a preset shape;

[0040] In step S4, when preparing the battery electrode assembly, the multiple bonding units on the ceramic layer or the multiple bonding units on the base film are arranged alternately with the multiple lithium replenishment units on the negative electrode active material layer.

[0041] Preferably, in step S21, the ceramic layer slurry includes ceramic additives, binders, and dispersants;

[0042] The solid content of the ceramic layer slurry is 20-35%;

[0043] The solutes in the ceramic layer slurry include ceramic additives and binders;

[0044] Ceramic additives, specifically bauxite or alumina;

[0045] The adhesive is polyvinylidene fluoride (PVDF).

[0046] The dispersant is NMP (N-methylpyrrolidone);

[0047] The proportions of ceramic additives and binders in the total mass of solute in the ceramic layer slurry are 83%-97% and 3%-17%, respectively.

[0048] Preferably, the adhesive unit solution is a PVDF solution, the solvent of which is N-methylpyrrolidone or dimethyl carbonate, the solute is polyvinylidene fluoride (PVDF), and the solid content of the PVDF solution is 45-80%.

[0049] As can be seen from the technical solutions provided by the present invention above, compared with the prior art, the present invention provides a lithium-filled battery electrode assembly and preparation method, and a lithium-filled battery. Its design is scientific, which can effectively improve the energy density of the battery and ensure a long cycle life, which has great practical significance.

[0050] Compared with the prior art, the negative electrode plate designed in the lithium-replenishing battery of the present invention has better in-plane potential uniformity. Through the design of multiple lithium-replenishing units, lithium replenishment can be performed more quickly, and the SEI film formed on the electrode plane is more uniform, effectively avoiding local electrode failure.

[0051] Compared with the prior art, the multi-element negative electrode active layer designed in the lithium-replenishing battery electrode assembly of the present invention, combined with the lithium-replenishing unit, can achieve a significant improvement in cycle life;

[0052] Compared with the prior art, the separator designed in the lithium-filled battery electrode assembly of the present invention can effectively reduce the problem of high in-cell ratio caused by the presence of lithium-filled units by cooperating with the bonding unit and the lithium-filled unit, thereby improving the energy density of the battery. Attached Figure Description

[0053] Figure 1 A schematic diagram showing the split structure of the negative electrode and the separator in a lithium-filled battery electrode assembly provided by the present invention;

[0054] Figure 2 This invention provides a basic flowchart of a method for preparing a lithium-filled battery electrode assembly. Detailed Implementation

[0055] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0056] This invention provides a lithium-filled battery electrode assembly, comprising a positive electrode, a negative electrode, and a separator;

[0057] The separator is located between the positive and negative electrode plates;

[0058] A battery electrode assembly is an assembly prepared by winding or stacking positive electrode plates, negative electrode plates, and a separator.

[0059] In this invention, specifically, the negative electrode sheet includes a copper foil current collector, a negative electrode active material layer, a lithium replenishment unit, and a protective layer.

[0060] The upper and lower surfaces of the copper foil current collector are coated with a layer of negative electrode active material.

[0061] Each layer of negative electrode active material has multiple lithium replenishment units uniformly adhered on the side away from the copper foil current collector.

[0062] A protective layer is sprayed onto the exposed surface (i.e., outer surface) of each negative electrode active material layer and each lithium replenishment unit. This protective layer is sprayed onto the entire surface of the negative electrode sheet.

[0063] It should be noted that the protective layer is sprayed on the surface of the negative electrode to reduce the reactivity of the lithium replenishment unit, and it will not introduce too many impurities into the lithium battery.

[0064] In practice, the negative electrode active material layer includes the negative electrode active material, conductive agent, dispersant and binder;

[0065] The proportions of the negative electrode active material, conductive agent, dispersant, and binder in the total mass of the negative electrode active material layer are 90%-98%, 0.1-2%, 0.3-3%, and 1-5%, respectively.

[0066] In specific implementation, the negative electrode active material includes at least two of the following: natural graphite, artificial graphite, soft carbon, hard carbon, and silicon.

[0067] It should be noted that materials such as natural graphite, artificial graphite, soft carbon, hard carbon, and silicon are the main materials for lithium storage and are negative electrode materials used in lithium batteries.

[0068] In specific implementation, for the negative electrode active material layer, the binder includes at least one of styrene-butadiene rubber, polyacrylate, polyacrylonitrile, and polyvinylidene fluoride.

[0069] In specific implementation, for the negative electrode active material layer, the conductive agent may include at least one of spherical graphite, carbon nanotubes and graphene.

[0070] For the negative electrode active material layer, the dispersant can specifically be a cellulose derivative, such as a carboxymethylated derivative.

[0071] In specific implementation, the lithium replenishment unit is a lithium metal monomer of a preset shape, such as a regular polygon, a circle or an irregular polygon.

[0072] In practice, the thickness of the lithium replenishment unit is 100nm to 20um.

[0073] In practice, the length of the lithium replenishment unit is 1mm to 20cm.

[0074] In practice, the lithium replenishment unit is attached to the surface of the negative electrode active material layer through physical adsorption.

[0075] It should be noted that the multiple lithium replenishment units are arranged in a certain array pattern, but not continuously. This arrangement pattern encompasses all array arrangements.

[0076] It should be noted that lithium metal is malleable, and the adhesion of lithium metal to the negative electrode surface can be adjusted by rolling. From a microscopic perspective, the surface of the negative electrode active material layer has a certain degree of unevenness. After rolling, lithium metal will use this interlocking force to bond with the negative electrode active material layer, thereby achieving physical adsorption.

[0077] In practice, when the upper and lower surfaces of the copper foil current collector are coated with a layer of negative electrode active material, the multiple lithium replenishment units on the two layers of negative electrode active material are arranged in an alternating manner, that is, they are relatively staggered and do not overlap.

[0078] It should be noted that multiple lithium replenishment units are staggered and do not overlap on the two outer surfaces of the two negative electrode active material layers. This design can effectively improve the uniformity of the potential distribution of the negative electrode sheet.

[0079] It should be noted that, for the present invention, the composite of multiple lithium replenishment units and negative electrode active material layers needs to be coated with a protective layer.

[0080] In practice, the protective layer is an insulating organic film, including but not limited to this.

[0081] In practice, the organic protective layer is sprayed onto the surface of the lithium replenishment unit in the form of liquid spray;

[0082] In practice, the solvent of the protective layer liquid includes at least one of EC, DMC and DEC, and the solute is polyalkylene microparticles; for example, the solute is polyvinylidene fluoride.

[0083] In practice, the solute of the protective layer liquid can be particles such as polyvinylidene fluoride, polytetrafluoroethylene, or polypropylene, with a particle size range of 50 nm to 10 μm.

[0084] The solid content of the protective layer liquid is 20-40%;

[0085] In practice, the thickness of the protective layer ranges from 0.5 nm to 23 μm.

[0086] In this invention, specifically, the positive electrode sheet includes an aluminum foil current collector and a positive electrode active material layer;

[0087] The upper and lower surfaces of the aluminum foil current collector are coated with a layer of positive electrode active material.

[0088] Alternatively, a layer of positive electrode active material may be coated on the upper or lower surface of the aluminum foil current collector.

[0089] In practice, the positive electrode active material layer includes the positive electrode active material, a conductive agent, and a binder;

[0090] Positive electrode active materials include lithium iron phosphate materials or ternary nickel-cobalt-manganese materials;

[0091] Conductive agents, including one or both of conductive carbon black and carbon nanotubes;

[0092] Adhesives, including at least one of PVDF, PTFE, PAN and PMMA;

[0093] The proportions of the positive electrode active material, conductive agent, and binder in the total mass of the positive electrode active material layer are 91%-99%, 0.1-4.5%, and 0.1-5%, respectively.

[0094] In this invention, specifically, the diaphragm is either a first diaphragm or a second diaphragm;

[0095] The first separator specifically includes a base membrane, a ceramic layer, and bonding units, and a ceramic layer is disposed on the side of the base membrane facing the positive electrode; multiple bonding units are disposed on the ceramic layer;

[0096] The second separator specifically includes a base membrane and bonding units, with multiple bonding units disposed on the side of the base membrane facing the positive electrode.

[0097] It should be noted that the bonding unit is a monomer with a special shape, and the bonding monomer is regularly distributed on the surface of the base film.

[0098] It should be noted that the ceramic layer is optional for the diaphragm of this invention.

[0099] In specific implementation, the base film can be a PP film or a PE film, or a double-layer composite membrane including one PP film and one PE film, or a three-layer composite membrane including two PP films and one PE film, or a three-layer composite membrane including one PP film and two PE films.

[0100] In practice, the ceramic layer (i.e., the solid ceramic layer) includes ceramic additives and binders;

[0101] The proportions of ceramic additives and binders in the total mass of the ceramic layer (i.e., the solid ceramic layer) are 83%-97% and 3-17%, respectively.

[0102] It should be noted that for ceramic layer slurry, the dispersant in it only plays a dispersing role. When the ceramic layer is dried to form a solid ceramic layer, the dispersant (NMP) is volatilized.

[0103] Among them, ceramic additives are specifically borosilicate or alumina;

[0104] For the ceramic layer, the binder is polyvinylidene fluoride (PVDF).

[0105] In specific implementation, the bonding unit is a coagulated colloid of a preset shape, such as a regular polygon, a circle, or an irregular polygon.

[0106] In the battery electrode assembly, multiple bonding units on the ceramic layer of the first separator or multiple bonding units on the base film of the second separator are arranged in an alternating manner with multiple lithium replenishment units on the negative electrode active material layer (i.e., forming a spatial staggered arrangement).

[0107] In practice, the bonding unit and the lithium replenishment unit have the same shape, size and thickness.

[0108] It should be noted that multiple bonding units are scattered on the surface of the base film in an array, and these bonding units and the lithium replenishment units in the negative electrode are spatially staggered. That is, when the battery electrode assembly is made, the bonding units and the lithium replenishment units have no thickness overlap, and these bonding units can be coated on one or both sides of the base film surface.

[0109] In practice, the adhesive component of the bonding unit is polyvinylidene fluoride (PVDF).

[0110] In practice, the thickness of the bonding unit ranges from 100 nm to 12 μm.

[0111] It should be noted that, in specific implementation, the bonding unit is formed as follows: after dispersing the solute polyvinylidene fluoride (PVDF) with a solvent, a bonding unit adhesive (i.e., PVDF adhesive) is formed, which is then sprayed onto the surface of the ceramic layer or base film, and bonded by the adhesive force of the adhesive itself; wherein, the solvent of the PVDF adhesive is N-methylpyrrolidone or dimethyl carbonate; the solute is polyvinylidene fluoride (PVDF), and the solid content of the PVDF adhesive is 45-80%; the shape of the bonding unit is ensured by the nozzle of the existing spraying equipment.

[0112] See Figure 1 As shown, for the lithium-filled battery electrode assembly provided by the present invention, a plurality of lithium-filled units 2 are provided on the negative electrode active material layer on the upper side of the negative electrode sheet 1.

[0113] A positive electrode 5 is disposed above the base membrane 3 of the separator;

[0114] The base film 3 of the separator adjacent to the negative electrode 1 has multiple bonding units 4 on the side opposite to the positive electrode 5;

[0115] In the battery electrode assembly, multiple bonding units 4 on the base film 3 of the separator and multiple lithium replenishment units on the negative electrode active material layer on the upper side of the negative electrode sheet 1 are arranged in an alternating manner (i.e., forming a spatial staggered arrangement).

[0116] It should be noted that, in this invention, the positive electrode, negative electrode, and separator are formed into a battery electrode assembly by winding or stacking. The special structure of this battery electrode assembly is that the thickness of the bonding unit of the separator and the lithium replenishment unit of the negative electrode are not superimposed. The advantage of this design is that it does not increase the thickness of the electrode assembly, and to a certain extent avoids the problem of low energy density caused by excessively high in-shell ratio.

[0117] It should be noted that, based on the above technical solutions, this invention obtains a lithium-supplemented battery through the design of the negative electrode formulation and structure, and the design of the separator. The negative electrode includes various main materials, a lithium-supplementation unit, and a protective layer. The separator includes a base film, a ceramic layer, and a bonding unit. The bonding unit and the lithium-supplementation unit have an intercalated structure. The battery assembled with the above structure features high energy density and long cycle life. This design provides a solution to a key issue of concern in the industry.

[0118] Based on the lithium-filled battery electrode assembly provided by the present invention, the present invention also provides a lithium-filled battery, including the aforementioned lithium-filled battery electrode assembly.

[0119] In this invention, specifically, the lithium-filled battery electrode assembly is located inside the battery casing;

[0120] The battery casing can be either a hard casing or a soft packaging casing;

[0121] The battery casing is filled with existing non-aqueous electrolyte.

[0122] See Figure 2 This invention provides a method for preparing a lithium-filled battery, comprising the following steps:

[0123] Step S1, preparation of the negative electrode sheet;

[0124] Step S2, preparation of the diaphragm;

[0125] Step S3, Preparation of positive electrode sheet: The positive electrode active material, conductive agent and binder are mixed evenly according to the preset mass ratio, and then dispersed in a solvent to prepare a positive electrode active material slurry. The positive electrode active material slurry is then evenly coated on the surface of the aluminum foil current collector, and then dried and rolled in sequence to obtain the positive electrode sheet.

[0126] Step S4, Preparation of battery electrode assembly: The positive electrode sheet, separator and negative electrode sheet cut according to the preset specifications are prepared into a battery electrode assembly by winding or stacking.

[0127] For this invention, step S1, the preparation of the negative electrode sheet, specifically includes the following sub-steps:

[0128] Step S11: Mix at least two negative electrode active materials evenly, then disperse them in a solvent, and then add a conductive agent, a dispersant, and a binder in sequence, and continue stirring to form a negative electrode active material slurry (i.e., a negative electrode conductive slurry).

[0129] Step S12: The negative electrode active material slurry is uniformly attached to the copper foil current collector by spraying, and then the negative electrode sheet is obtained by drying and rolling processes.

[0130] Step S13: Multiple lithium replenishment units are uniformly disposed on the surface of the negative electrode active material layer of the unlithiated negative electrode sheet obtained in step S12. Then, a protective layer solution is uniformly sprayed on the surface of the negative electrode active material layer and the lithium replenishment units. After drying, the finished negative electrode sheet is obtained.

[0131] In step S11, specifically, the solvent in the negative electrode active material slurry is water;

[0132] The solid content of the negative electrode active material slurry is 40-60%, and the viscosity is 2500-4500 cp;

[0133] In step S11, specifically, the solute of the negative electrode active material slurry includes the negative electrode active material, conductive agent, dispersant and binder;

[0134] The proportions of the negative electrode active material, conductive agent, dispersant, and binder in the total mass of the solute in the negative electrode active material slurry are 90%-98%, 0.1-2%, 0.3-3%, and 1-5%, respectively.

[0135] In step S1, specifically, a planetary mixer is used for mixing.

[0136] In step S1, specifically, the total stirring time is controlled within 6 hours, and the maximum speed is <2500 rpm.

[0137] In step S11, specifically, the first composition ratio scheme of the negative electrode active material slurry is as follows: when the three negative electrode active materials A, B and C are stirred and mixed evenly, the three negative electrode active materials A, B and C are artificial graphite, hard carbon and soft carbon, respectively.

[0138] The mass ratio of the three negative electrode active materials A, B and C is 4:1:1;

[0139] The three negative electrode active materials, A, B, and C, are added to the stirrer in the specified mass ratio, i.e., the addition order is ABC, the stirring time is 60 minutes, and the stirring speed is 15 rpm.

[0140] In step S11, specifically, the second composition ratio scheme of the negative electrode active material slurry is as follows: when the two negative electrode active materials A and B are stirred and mixed evenly, the two negative electrode active materials A and B are artificial graphite and hard carbon, respectively.

[0141] The mass ratio of the two negative electrode active materials, A and B, is 6:1.

[0142] The two negative electrode active materials, A and B, are added to the stirrer in the specified mass ratio, i.e., the addition order is AB, the stirring time is 60 minutes, and the stirring speed is 15 rpm.

[0143] In step S13, specifically, the lithium replenishment unit is attached to the surface of the negative electrode active material layer by physical adsorption.

[0144] It should be noted that lithium metal is malleable, and the adhesion of lithium metal to the negative electrode surface can be adjusted by rolling. From a microscopic perspective, the surface of the negative electrode active material layer has a certain degree of unevenness. After rolling, lithium metal will use this interlocking force to bond with the negative electrode active material layer, thereby achieving physical adsorption.

[0145] In step S13, specifically, the lithium replenishment unit is a lithium metal monomer of a preset shape, such as a regular polygon, a circle, or an irregular polygon.

[0146] The thickness of the lithium replenishment unit is 100nm to 20um.

[0147] The length of the lithium replenishment unit is 1mm to 20cm.

[0148] In step S13, specifically, the spacing between any two adjacent lithium replenishment units is 8 mm.

[0149] It should be noted that the multiple lithium replenishment units are staggered and do not overlap on the negative electrode active material layers on the upper and lower sides of the copper foil current collector: the lower lithium replenishment unit is centrally located directly below the gap formed between the upper lithium replenishment units.

[0150] In practice, when the upper and lower surfaces of the copper foil current collector are coated with a layer of negative electrode active material, the multiple lithium replenishment units on the two layers of negative electrode active material are arranged in an alternating manner, that is, they are relatively staggered and do not overlap. It should be noted that the multiple lithium replenishment units are relatively staggered and do not overlap on the two outer surfaces of the two layers of negative electrode active material. This design can effectively improve the uniformity of the potential distribution of the negative electrode sheet.

[0151] In step S13, specifically, the solute of the protective layer solution is polyvinylidene fluoride, the solvent is DMC, the solid content of the protective layer liquid is 20-40%, the mixture of polyvinylidene fluoride and DMC (i.e., the mixed solution, also known as the protective layer solution) is sprayed onto the surface of the lithium replenishment unit and dried at 60°C for 10 minutes. After drying, the thickness of the protective layer is 100 nm.

[0152] In practice, the solute of the protective layer liquid can be particles such as polyvinylidene fluoride, polytetrafluoroethylene, or polypropylene, with a particle size range of 50 nm to 10 μm.

[0153] The solid content of the protective layer liquid is 20-40%;

[0154] In practice, the thickness of the protective layer ranges from 0.5 nm to 23 μm.

[0155] For this invention, step S2, the preparation of the diaphragm, specifically includes step S21 or step S22:

[0156] Step S21: Mix and stir the ceramic additive, binder and dispersant evenly to obtain a ceramic layer slurry. Then, coat the ceramic layer slurry onto the side of the base film facing the positive electrode and dry it to obtain a base film with a ceramic layer. Then, spray multiple bonding unit adhesive liquids onto the ceramic layer and dry it to form bonding units on the ceramic layer.

[0157] Step S22: Spray multiple bonding unit adhesives onto the side of the base film facing the positive electrode, and then dry it to form bonding units on the base film.

[0158] In step S21, the ceramic layer slurry includes ceramic additives, binders, and dispersants (the dispersant acts as a solvent);

[0159] The solid content of the ceramic layer slurry is 20-35%;

[0160] The solutes in the ceramic layer slurry include ceramic additives and binders;

[0161] The proportions of ceramic additives and binders in the total mass of solute in the ceramic layer slurry are 83%-97% and 3-17%, respectively.

[0162] It should be noted that for ceramic layer slurry, the dispersant in it only plays a dispersing role. When the ceramic layer is dried to form a solid ceramic layer, the dispersant (NMP) is volatilized.

[0163] Among them, ceramic additives are specifically borosilicate or alumina;

[0164] The adhesive is polyvinylidene fluoride (PVDF).

[0165] The dispersant is NMP (N-methylpyrrolidone).

[0166] In specific implementation, in steps S21 and S22, the bonding unit is a coagulated colloid of a preset shape; for example, a coagulated colloid of a regular polygon, a circle, or an irregular polygon.

[0167] In step S4, when preparing the battery electrode assembly, the multiple bonding units on the ceramic layer or the multiple bonding units on the base film are arranged alternately with the multiple lithium replenishment units on the negative electrode active material layer (i.e., forming a spatial staggered arrangement).

[0168] In practice, the bonding unit and the lithium replenishment unit have the same shape, size and thickness.

[0169] It should be noted that multiple bonding units are scattered on the surface of the base film in an array, and these bonding units and the lithium replenishment units in the negative electrode are spatially staggered. That is, when the battery electrode assembly is made, the bonding units and the lithium replenishment units have no thickness overlap, and these bonding units can be coated on one or both sides of the base film surface.

[0170] In specific implementation, in step S2, the colloidal component of the bonding unit is polyvinylidene fluoride (PVDF).

[0171] In specific implementation, in step S2, the thickness of the bonding unit ranges from 100 nm to 12 μm.

[0172] It should be noted that, in specific implementation, the bonding unit is formed as follows: after dispersing the solute polyvinylidene fluoride (PVDF) in a solvent, a bonding unit adhesive (i.e., PVDF adhesive) is formed, which is then sprayed onto the surface of the ceramic layer or base film, and bonded by the adhesive force of the adhesive itself; wherein, the solvent of the bonding unit adhesive (i.e., PVDF adhesive) is N-methylpyrrolidone or dimethyl carbonate; the solute is polyvinylidene fluoride (PVDF), and the solid content of the PVDF adhesive is 45-80%; the shape of the bonding unit is ensured by the nozzle of the existing spraying equipment.

[0173] In a specific implementation of the present invention, the positive electrode sheet includes an aluminum foil current collector and a positive electrode active material layer;

[0174] The upper and lower surfaces of the aluminum foil current collector are coated with a layer of positive electrode active material.

[0175] Alternatively, a layer of positive electrode active material may be coated on the upper or lower surface of the aluminum foil current collector.

[0176] In practice, the solutes in the positive electrode active material slurry include the positive electrode active material, conductive agent, and binder;

[0177] Positive electrode active materials include lithium iron phosphate materials or ternary nickel-cobalt-manganese materials;

[0178] Conductive agents, including one or both of conductive carbon black and carbon nanotubes;

[0179] Adhesives, including at least one of PVDF, PTFE, PAN and PMMA;

[0180] The proportions of the positive electrode active material, conductive agent, and binder in the total mass of the solute in the positive electrode active material slurry are 96%, 2%, and 2%, respectively.

[0181] In specific implementation, in step S3, the solvent of the positive electrode active material slurry is NMP, and the solid content of the positive electrode active material slurry is 40-60%.

[0182] To better understand the technical solution of the present invention, the following specific embodiments will be used to illustrate the technical solution of the present invention.

[0183] Example 1.

[0184] In Example 1, a lithium-filled battery is prepared, comprising the following steps:

[0185] Step S1, preparation of the negative electrode sheet;

[0186] Step S2, preparation of the diaphragm;

[0187] Step S3, Preparation of positive electrode sheet: The positive electrode active material, conductive agent and binder are mixed evenly according to the preset mass ratio, and then dispersed in a solvent to prepare a positive electrode active material slurry. The positive electrode active material slurry is then evenly coated on the surface of the aluminum foil current collector, and then dried and rolled in sequence to obtain the positive electrode sheet.

[0188] Step S4, Preparation of battery electrode assembly: The positive electrode sheet, separator and negative electrode sheet cut according to the preset specifications are stacked to prepare a stacked battery electrode assembly.

[0189] In Example 1, the preparation of the negative electrode sheet in step S1 includes the following steps:

[0190] Step S11: Mix the three negative electrode active materials A, B and C evenly, then disperse them in a solvent, and then add the conductive agent, dispersant and binder in sequence, and continue stirring to form a negative electrode active material slurry (i.e. negative electrode conductive slurry).

[0191] Step S12: The negative electrode active material slurry is uniformly attached to the copper foil current collector by spraying, and then the negative electrode sheet is obtained by drying and rolling processes.

[0192] Step S13: Multiple lithium replenishment units are uniformly disposed on the surface of the negative electrode active material layer of the unlithiated negative electrode sheet obtained in step S12. Then, a protective layer solution is uniformly sprayed on the surface of the negative electrode active material layer and the lithium replenishment units. After drying, the finished negative electrode sheet is obtained.

[0193] In Example 1, in step S11, the solvent in the negative electrode active material slurry is water;

[0194] The solid content of the negative electrode active material slurry is 40-60%, and the viscosity is 2500-4500 cp;

[0195] In Example 1, in step S1, a negative stirring operation is performed by a planetary stirrer.

[0196] In Example 1, the total stirring time was controlled within 6 hours and the maximum speed was <2500 rpm.

[0197] In step S11, specifically, the solute of the negative electrode active material slurry includes the negative electrode active material, conductive agent, dispersant and binder;

[0198] The proportions of the negative electrode active material, conductive agent, dispersant, and binder in the total mass of the solute in the negative electrode active material slurry are 96.5%, 0.5%, 1%, and 2%, respectively.

[0199] In step S11, specifically, when the three negative electrode active materials A, B and C are stirred and mixed evenly, the three negative electrode active materials A, B and C are artificial graphite, hard carbon and soft carbon, respectively.

[0200] The mass ratio of the three negative electrode active materials A, B and C is 4:1:1;

[0201] The three negative electrode active materials, A, B, and C, are added to the stirrer in the specified mass ratio, i.e., the addition order is ABC, the stirring time is 60 minutes, and the stirring speed is 15 rpm.

[0202] In Example 1, in step S13, specifically, the lithium replenishment unit is attached to the surface of the negative electrode active material layer by physical adsorption.

[0203] In Example 1, in step S13, specifically, the lithium replenishment unit is a square lithium metal monomer; the thickness of the lithium replenishment unit is 3µm. The side length of the square lithium replenishment unit is 5mm. The spacing between any two adjacent lithium replenishment units is 8mm.

[0204] In Example 1, multiple lithium replenishment units are staggered and do not overlap on the negative electrode active material layers on the upper and lower sides of the copper foil current collector: the lower lithium replenishment unit is centrally located directly below the gap formed between the upper lithium replenishment units.

[0205] In Example 1, in step S13, specifically, the solute of the protective layer solution is polyvinylidene fluoride and the solvent is DMC. The mixture of the two (i.e., the mixed solution) is sprayed onto the surface of the lithium replenishment unit and dried at 60°C for 10 minutes. After drying, the thickness of the protective layer is 100 nm.

[0206] In Example 1, step S2, the preparation of the diaphragm, specifically includes step S21 or step S22:

[0207] Step S21: Mix and stir the ceramic additive, binder and dispersant evenly to obtain a ceramic layer slurry. Then, coat the ceramic layer slurry onto the side of the base film facing the positive electrode and dry it to obtain a base film with a ceramic layer. Then, spray multiple bonding units onto the ceramic layer.

[0208] Step S22: Spray multiple bonding units onto the side of the base film facing the positive electrode sheet;

[0209] In step S21, the ceramic layer slurry includes ceramic additives, binders, and dispersants (the dispersants are used as solvents);

[0210] The solid content of the ceramic layer slurry is 20-35%;

[0211] The solutes in the ceramic layer slurry include ceramic additives and binders;

[0212] The proportions of ceramic additives and binders in the total mass of solute in the ceramic layer slurry are 85% and 15%, respectively.

[0213] It should be noted that for ceramic layer slurry, the dispersant in it only plays a dispersing role. When the ceramic layer is dried to form a solid ceramic layer, the dispersant (NMP) is volatilized.

[0214] Among them, ceramic additives are specifically borosilicate or alumina;

[0215] The adhesive is polyvinylidene fluoride (PVDF).

[0216] The dispersant is NMP (N-methylpyrrolidone).

[0217] In Example 1, specifically, the base film is a single-layer PE matrix.

[0218] In Example 1, specifically, the bonding unit is a square solidified colloid;

[0219] In the battery electrode assembly, multiple bonding units on the ceramic layer and multiple lithium replenishment units on the negative electrode active material layer are arranged in an alternating manner (i.e., forming a spatial staggered arrangement).

[0220] In Example 1, the bonding unit and the lithium replenishment unit have the same shape, size and thickness.

[0221] It should be noted that multiple bonding units are scattered on the surface of the base film in an array, and these bonding units and the lithium replenishment units in the negative electrode are spatially staggered. That is, when the battery electrode assembly is made, the bonding units and the lithium replenishment units have no thickness overlap, and these bonding units can be coated on one or both sides of the base film surface.

[0222] In Example 1, specifically, the adhesive component of the bonding unit is polyvinylidene fluoride (PVDF).

[0223] In Example 1, in step S3, a layer of positive electrode active material is coated on the upper and lower surfaces of the aluminum foil current collector.

[0224] In Example 1, in step S3, the positive electrode active material layer includes a positive electrode active material, a conductive agent, and a binder;

[0225] In Example 1, in step S3, the positive electrode active material is lithium iron phosphate.

[0226] In Example 1, in step S3, the conductive agent includes one or both of conductive carbon black and carbon nanotubes;

[0227] In Example 1, the adhesive includes at least one of PVDF, PTFE, PAN and PMMA;

[0228] In Example 1, in step S3, the solute of the positive electrode active material slurry includes the positive electrode active material, the conductive agent, and the binder;

[0229] The solvent for the positive electrode active material slurry is NMP, and the solid content of the positive electrode active material slurry is 40-60%.

[0230] The proportions of the total mass of solutes in the positive electrode active material slurry, conductive agent, and binder are 97%, 1%, and 2%, respectively.

[0231] In Example 1, the stacked battery electrode assembly obtained in step S4 is then subjected to the existing processes of casing, drying, liquid injection, venting, formation, aging and capacity testing to obtain the finished square stacked lithium-ion battery.

[0232] After testing, the battery obtained based on the above embodiments, with the above innovations, compared with ordinary batteries that do not have the above-mentioned negative electrode lithium replenishment design, negative electrode sheet design, and related structural design, has a 15% higher energy density and a 5% higher cycle life.

[0233] Example 2.

[0234] In Example 2, a lithium-filled battery is prepared, comprising the following steps:

[0235] Step S1, preparation of the negative electrode sheet;

[0236] Step S2, preparation of the diaphragm;

[0237] Step S3, Preparation of positive electrode sheet: The positive electrode active material, conductive agent and binder are mixed evenly according to the preset mass ratio, and then dispersed in a solvent to prepare a positive electrode active material slurry. The positive electrode active material slurry is then evenly coated on the surface of the aluminum foil current collector, and then dried and rolled in sequence to obtain the positive electrode sheet.

[0238] Step S4, Preparation of battery electrode assembly: The positive electrode sheet, separator and negative electrode sheet cut according to the preset specifications are stacked to prepare a stacked battery electrode assembly.

[0239] In Example 2, the preparation of the negative electrode sheet in step S1 includes the following steps:

[0240] Step S11: Mix the two negative electrode active materials A and B evenly, then disperse them in a solvent, and then add the conductive agent, dispersant, and binder in sequence, and continue stirring to form a negative electrode active material slurry (i.e., negative electrode conductive slurry).

[0241] Step S12: The negative electrode active material slurry is uniformly attached to the copper foil current collector by spraying, and then the negative electrode sheet is obtained by drying and rolling processes.

[0242] Step S13: Multiple lithium replenishment units are uniformly disposed on the surface of the negative electrode active material layer of the unlithiated negative electrode sheet obtained in step S12. Then, a protective layer solution is uniformly sprayed on the surface of the negative electrode active material layer and the lithium replenishment units. After drying, the finished negative electrode sheet is obtained.

[0243] In Example 2, in step S11, the solvent in the negative electrode active material slurry is water;

[0244] The solid content of the negative electrode active material slurry is 40-60%, and the viscosity is 2500-4500 cp;

[0245] In Example 2, in step S1, a negative stirring operation is performed by a planetary stirrer.

[0246] In Example 2, the total stirring time was controlled within 6 hours, and the maximum speed was <2500 rpm.

[0247] In step S11, specifically, the solute of the negative electrode active material slurry includes the negative electrode active material, conductive agent, dispersant and binder;

[0248] The proportions of the negative electrode active material, conductive agent, dispersant, and binder in the total mass of the solute in the negative electrode active material slurry are 97%, 0.5%, 1%, and 1.5%, respectively.

[0249] In step S11, specifically, when the two negative electrode active materials A and B are stirred and mixed evenly, the two negative electrode active materials A and B are artificial graphite and hard carbon, respectively.

[0250] The mass ratio of the two negative electrode active materials, A and B, is 6:1.

[0251] The two negative electrode active materials, A and B, are added to the stirrer in the specified mass ratio, i.e., the addition order is AB, the stirring time is 60 minutes, and the stirring speed is 15 rpm.

[0252] In Example 2, in step S13, specifically, the lithium replenishment unit is attached to the surface of the negative electrode active material layer by physical adsorption.

[0253] In Example 2, in step S13, specifically, the lithium replenishment unit is a square lithium metal monomer; the thickness of the lithium replenishment unit is 3µm. The side length of the square lithium replenishment unit is 5mm. The spacing between any two adjacent lithium replenishment units is 8mm.

[0254] In Example 2, multiple lithium replenishment units are staggered and do not overlap on the negative electrode active material layers on both sides of the copper foil current collector: the lower lithium replenishment unit is centrally located directly below the gap formed between the upper lithium replenishment units.

[0255] In Example 2, in step S13, specifically, the solute of the protective layer solution is polyvinylidene fluoride and the solvent is DMC. The mixture of the two (i.e., the mixed solution) is sprayed onto the surface of the lithium replenishment unit and dried at 60°C for 10 minutes. After drying, the thickness of the protective layer is 100 nm.

[0256] In Example 2, step S2, the preparation of the diaphragm, specifically includes step S21 or step S22:

[0257] Step S21: Mix and stir the ceramic additive, binder and dispersant evenly to obtain a ceramic layer slurry. Then, coat the ceramic layer slurry onto the side of the base film facing the positive electrode and dry it to obtain a base film with a ceramic layer. Then, spray multiple adhesive unit liquids onto the ceramic layer and dry it.

[0258] Step S22: Spray multiple bonding unit adhesives onto the side of the base film facing the positive electrode, and then dry it;

[0259] In Example 2, in step S21, the ceramic layer slurry includes ceramic additives, binders, and dispersants (the dispersants are used as solvents);

[0260] The solid content of the ceramic layer slurry is 20-35%;

[0261] The solutes in the ceramic layer slurry include ceramic additives and binders;

[0262] The proportions of ceramic additives and binders in the total mass of solute in the ceramic layer slurry are 89% and 11%, respectively.

[0263] It should be noted that for ceramic layer slurry, the dispersant in it only plays a dispersing role. When the ceramic layer is dried to form a solid ceramic layer, the dispersant (NMP) is volatilized.

[0264] Among them, ceramic additives are specifically borosilicate or alumina;

[0265] The adhesive is polyvinylidene fluoride (PVDF).

[0266] The dispersant is NMP (N-methylpyrrolidone);

[0267] In Example 2, specifically, the base film is a single-layer PP matrix.

[0268] In Example 2, specifically, the bonding unit is a square-shaped solidified colloid;

[0269] In the battery electrode assembly, multiple bonding units on the ceramic layer and multiple lithium replenishment units on the negative electrode active material layer are arranged in an alternating manner (i.e., forming a spatial staggered arrangement).

[0270] In Example 2, specifically, the bonding unit and the lithium replenishment unit have the same shape, size, and thickness.

[0271] It should be noted that multiple bonding units are scattered on the surface of the base film in an array, and these bonding units and the lithium replenishment units in the negative electrode are spatially staggered. That is, when the battery electrode assembly is made, the bonding units and the lithium replenishment units have no thickness overlap, and these bonding units can be coated on one or both sides of the base film surface.

[0272] In Example 2, specifically, the adhesive component of the bonding unit is polyvinylidene fluoride (PVDF).

[0273] In Example 2, in step S3, a layer of positive electrode active material is coated on the upper and lower surfaces of the aluminum foil current collector.

[0274] In practice, the thickness of the bonding unit ranges from 100 nm to 12 μm.

[0275] It should be noted that, in specific implementation, the bonding unit is formed as follows: after dispersing the solute polyvinylidene fluoride (PVDF) with a solvent, a bonding unit adhesive (i.e., PVDF adhesive) is formed, which is then sprayed onto the surface of the ceramic layer or base film, and bonded by the adhesive force of the adhesive itself; wherein, the solvent of the PVDF adhesive is N-methylpyrrolidone or dimethyl carbonate; the solute is polyvinylidene fluoride (PVDF), and the solid content of the PVDF adhesive is 45-80%; the shape of the bonding unit is ensured by the nozzle of the existing spraying equipment.

[0276] In Example 2, in step S3, the positive electrode active material layer includes a positive electrode active material, a conductive agent, and a binder;

[0277] In Example 2, in step S3, the positive electrode active material is a ternary nickel-cobalt-manganese material;

[0278] In Example 2, in step S3, the conductive agent includes one or both of conductive carbon black and carbon nanotubes;

[0279] In Example 2, the adhesive includes at least one of PVDF, PTFE, PAN and PMMA;

[0280] The solutes in the positive electrode active material slurry include the positive electrode active material, conductive agent, and binder;

[0281] The proportions of the positive electrode active material, conductive agent, and binder in the total mass of the solute in the positive electrode active material slurry are 97%, 1%, and 2%, respectively.

[0282] In specific implementation, in step S3, the solvent of the positive electrode active material slurry is NMP, and the solid content of the positive electrode active material slurry is 40-60%.

[0283] In Example 2, the stacked battery electrode assembly obtained in step S4 is then subjected to the existing processes of casing, drying, liquid injection, venting, formation, aging and capacity testing to obtain the finished square stacked lithium-ion battery.

[0284] After testing, the battery obtained based on the above embodiments, with the above innovations, compared with ordinary batteries that do not have the above-mentioned negative electrode lithium replenishment design, negative electrode sheet design, and related structural design, has an energy density that is increased by 13.5% and a cycle life that is increased by 6.1%.

[0285] In summary, compared with the prior art, the lithium-filled battery electrode assembly and preparation method and the lithium-filled battery provided by this invention are scientifically designed, can effectively improve the energy density of the battery, and ensure a long cycle life, which has significant practical significance.

[0286] Compared with the prior art, the negative electrode plate designed in the lithium-replenishing battery of the present invention has better in-plane potential uniformity. Through the design of multiple lithium-replenishing units, lithium replenishment can be performed more quickly, and the SEI film formed on the electrode plane is more uniform, effectively avoiding local electrode failure.

[0287] Compared with the prior art, the multi-element negative electrode active layer designed in the lithium-replenishing battery electrode assembly of the present invention, combined with the lithium-replenishing unit, can achieve a significant improvement in cycle life;

[0288] Compared with the prior art, the separator designed in the lithium-filled battery electrode assembly of the present invention can effectively reduce the problem of high in-cell ratio caused by the presence of lithium-filled units by cooperating with the bonding unit and the lithium-filled unit, thereby improving the energy density of the battery.

[0289] It should be noted that in this invention, the lithium replenishment unit in the battery electrode assembly can replenish active lithium, provide a lithium source for lithium battery cycling, and improve the energy density and cycle performance of the battery.

[0290] In this invention, the bonding unit (i.e., the binder unit) serves two purposes: firstly, it secures the electrode assembly, ensuring minimal expansion of the electrode assembly during cycling and improving cycle performance; secondly, the bonding unit can reduce the thickness of the electrode assembly through cross-cooperation with the lithium replenishment unit, thereby indirectly improving the energy density of the battery.

[0291] In this invention, specifically, the bonding unit 4 can be disposed on one or both sides of the separator, but it must be disposed on the positive electrode side of the separator (i.e., the side facing the positive electrode 5); the ceramic layer of the separator can be disposed only on the positive electrode side (i.e., the side facing the positive electrode 5).

[0292] In this invention, the lithium replenishment unit 2 is located on both sides of the negative electrode 1, and the upper and lower sides of the negative electrode 1 have negative electrode active material layers.

[0293] It should be noted that the lithium replenishment unit 2 is definitely present on both sides of the negative electrode 1. Figure 1 In the image, the lithium replenishment unit 2 on the bottom surface of the negative electrode is obscured and cannot be displayed.

[0294] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A lithium-filled battery electrode assembly, characterized in that, Includes positive electrode, negative electrode, and separator; The separator is located between the positive and negative electrode plates; A battery electrode assembly is an electrode assembly prepared by winding or stacking positive electrode sheets, negative electrode sheets, and a separator. The negative electrode sheet includes a copper foil current collector, a negative electrode active material layer, a lithium replenishment unit, and a protective layer; The upper and lower surfaces of the copper foil current collector are coated with a layer of negative electrode active material. On the side away from the copper foil current collector, each layer of negative electrode active material has multiple lithium replenishment units uniformly adhered; the multiple lithium replenishment units on the two layers of negative electrode active material are arranged in an alternating manner. A protective layer is sprayed onto the exposed surface of each negative electrode active material layer and each lithium replenishment unit. The lithium replenishment unit is a lithium metal monomer of a predetermined shape; The diaphragm may be a first diaphragm or a second diaphragm; The first separator specifically includes a base membrane, a ceramic layer, and bonding units, and a ceramic layer is disposed on the side of the base membrane facing the positive electrode; multiple bonding units are disposed on the ceramic layer; The second separator specifically includes a base membrane and bonding units, with multiple bonding units disposed on the side of the base membrane facing the positive electrode sheet; The base film is a PP film or a PE film, or a double-layer composite membrane consisting of one PP film and one PE film, or a triple-layer composite membrane consisting of two PP films and one PE film, or a triple-layer composite membrane consisting of one PP film and two PE films. In the battery electrode assembly, multiple bonding units on the ceramic layer of the first separator or multiple bonding units on the base film of the second separator are arranged alternately with multiple lithium replenishment units on the negative electrode active material layer.

2. The lithium-filled battery electrode assembly as described in claim 1, characterized in that, The thickness of the lithium replenishment unit is 100 nm to 20 μm; The length of the lithium replenishment unit is 1mm to 20cm; The thickness of the protective layer ranges from 0.5 nm to 23 μm.

3. The lithium-filled battery electrode assembly as described in claim 1, characterized in that, The protective layer is an insulating organic film.

4. A lithium-ion battery, characterized in that, Includes the lithium-filled battery electrode assembly as described in any one of claims 1 to 3.

5. A method for preparing a lithium-filled battery as described in claim 4, characterized in that, Includes the following steps: Step S1, preparation of the negative electrode sheet; Step S2, preparation of the diaphragm; specifically including step S21 or step S22: Step S21: Mix and stir the ceramic additive, binder and dispersant evenly to obtain a ceramic layer slurry. Then, coat the ceramic layer slurry onto the side of the base film facing the positive electrode and dry it to obtain a base film with a ceramic layer. Then, spray multiple bonding unit adhesive liquids onto the ceramic layer and dry it to form bonding units on the ceramic layer. Step S22: Spray multiple bonding unit adhesives onto the side of the base film facing the positive electrode, and then dry it to form bonding units on the base film. In steps S21 and S22, the bonding unit is a coagulated colloid of a preset shape; In step S4, when preparing the battery electrode assembly, the multiple bonding units on the ceramic layer or the multiple bonding units on the base film are arranged alternately with the multiple lithium replenishment units on the negative electrode active material layer. Step S3, Preparation of positive electrode sheet: The positive electrode active material, conductive agent and binder are mixed evenly according to the preset mass ratio, and then dispersed in a solvent to prepare a positive electrode active material slurry. The positive electrode active material slurry is then evenly coated on the surface of the aluminum foil current collector, and then dried and rolled in sequence to obtain the positive electrode sheet. Step S4, Preparation of battery electrode assembly: The positive electrode sheet, separator and negative electrode sheet cut according to the preset specifications are prepared into a battery electrode assembly by winding or stacking. Specifically, step S1 includes the following sub-steps: Step S11: Mix at least two negative electrode active materials evenly, then disperse them in a solvent, and then add a conductive agent, a dispersant, and a binder in sequence, and continue stirring to form a negative electrode active material slurry. Step S12: The negative electrode active material slurry is uniformly attached to the copper foil current collector by spraying, and then the negative electrode sheet is obtained by drying and rolling processes. Step S13: Multiple lithium replenishment units are uniformly disposed on the surface of the negative electrode active material layer of the unlithiated negative electrode sheet obtained in step S12. Then, a protective layer solution is uniformly sprayed onto the surface of the negative electrode active material layer and the lithium replenishment units. After drying, the finished negative electrode sheet is obtained.

6. The method for preparing a lithium-ion battery as described in claim 5, characterized in that, The thickness of the lithium replenishment unit is 100 nm to 20 μm; The length of the lithium replenishment unit is 1mm to 20cm.

7. The method for preparing a lithium-ion battery as described in claim 5, characterized in that, In step S21, the ceramic layer slurry includes ceramic additives, binders, and dispersants; The solid content of the ceramic layer slurry is 20-35%; The solutes in the ceramic layer slurry include ceramic additives and binders; Ceramic additives, specifically bauxite or alumina; The adhesive is PVDF; The dispersant is NMP; The proportions of ceramic additives and binders in the total mass of solute in the ceramic layer slurry are 83%-97% and 3%-17%, respectively.

8. The method for preparing a lithium-ion battery as described in claim 5, characterized in that, The adhesive unit is a PVDF adhesive, with N-methylpyrrolidone or dimethyl carbonate as the solvent and PVDF as the solute; the solid content of the PVDF adhesive is 45-80%.

Images