Lithium battery cell, its manufacturing method, battery and electrical device

Abstract

The present invention provides a lithium battery cell, a manufacturing method thereof, a battery and an electric device. The lithium battery cell includes a negative electrode plate, and the negative electrode plate includes a negative electrode current collector, a negative electrode active material layer and a conductive layer. The negative electrode active material layer is disposed on the surface of the negative electrode current collector, and the conductive layer is disposed on the surface of the negative electrode active material layer away from the negative electrode current collector. The conductive layer includes a grid-like structure body and a phosphorus-containing compound, and the grid structure body includes a conductive gel, and the phosphorus-containing compound is filled in the grids of the grid-like structure body. The SEI film in the lithium battery cell has better stability, thereby helping to improve the cycle performance and service life of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a lithium battery cell, a manufacturing method thereof, a battery, and an electrical device. Background Art

[0002] With the increasing depletion of fossil energy, the development and utilization of new energy have attracted people's attention. Among them, as one of the representatives of new energy, batteries have been widely used in fields such as electric vehicles and energy storage.

[0003] During the production process of batteries, battery formation is a key step in the battery production process, aiming to activate the positive and negative electrode materials inside the battery cell through charge and discharge cycles and form a protective film on the surfaces of the positive and negative electrode plates. This protective film helps to improve the cycle performance and service life of the battery. Among them, the protective film formed on the surface of the negative electrode plate can be called a solid electrolyte interface film (Solid Electrolyte Interface, abbreviated as SEI film). However, in the related art, the stability of the above SEI film during the use of the battery is poor, resulting in a decline in the cycle performance and life of the battery. Summary of the Invention

[0004] The present invention provides a lithium battery cell, a manufacturing method thereof, a battery, and an electrical device. The SEI film in this lithium battery cell has good stability, which helps to improve the cycle performance and service life of the battery.

[0005] In the first aspect of the present invention, a lithium battery cell is provided, including a negative electrode plate. The negative electrode plate includes a negative current collector, a negative active material layer, and a conductive layer. The negative active material layer is disposed on the surface of the negative current collector, and the conductive layer is disposed on the surface of the negative active material layer away from the negative current collector. The conductive layer includes a grid-like structure body and a phosphorus-containing compound, and the grid structure body includes a conductive gel, and the phosphorus-containing compound is filled in the grids of the grid-like structure body.

[0006] According to any of the foregoing embodiments of the first aspect of the present invention, the size of the grids in the grid-like structure body is 0.01 mm - 0.1 mm.

[0007] According to any of the foregoing embodiments of the first aspect of the present invention, the conductive gel includes a conductive filler and a gel, and the conductive filler is doped into the gel to form the conductive gel. Among them, the mass ratio of the conductive filler to the gel is 1:(10 - 20).

[0008] According to any of the foregoing embodiments of the first aspect of the present invention, the gel includes a hydrophilic porous gel.

[0009] According to any of the foregoing embodiments of the first aspect of the present invention, the conductive filler includes at least one of carbon nanotubes, conductive polymers, and graphene.

[0010] According to any of the foregoing embodiments of the first aspect of the present invention, the thickness of the conductive layer is 50 nm - 200 nm.

[0011] According to any of the foregoing embodiments of the first aspect of the present invention, the phosphorus-containing compound includes at least one of elemental phosphorus, metal phosphides, and phosphates.

[0012] The second aspect of the present invention provides a manufacturing method of a lithium battery cell as described in any of the embodiments of the first aspect of the present invention, which is characterized by including:

[0013] Mix the raw materials of the negative electrode active material layer to form a negative electrode active paste;

[0014] Coat the negative electrode active paste on the surface of the negative electrode current collector and dry it to form a negative electrode active material layer on the surface of the negative electrode current collector;

[0015] Mix part of the raw materials of the conductive layer to form a conductive paste, and place the conductive paste in a mold, and form a grid-like structure after drying;

[0016] Bond the grid-like structure to the surface of the negative electrode active material layer away from the negative electrode current collector;

[0017] Disperse the phosphorus-containing compound in a solvent to form a phosphorus-containing paste;

[0018] Fill the phosphorus-containing paste into the grids in the grid-like structure, and form a conductive layer after drying to obtain a negative electrode plate.

[0019] The third aspect of the present invention provides a battery including a lithium battery cell as described in any of the embodiments of the first aspect of the present invention.

[0020] The fourth aspect of the present invention provides an electrical device including the battery as described in any of the embodiments of the third aspect of the present invention.

[0021] The present invention provides a lithium battery cell, a manufacturing method thereof, a battery and an electrical device. The lithium battery cell includes a negative electrode plate, and the negative electrode plate includes a negative electrode current collector, a negative electrode active material layer, and a conductive layer. The negative electrode active material layer is disposed on the surface of the negative electrode current collector, and the conductive layer is disposed on the surface of the negative electrode active material layer away from the negative electrode current collector. The conductive layer includes a grid-like structure body and a phosphorus-containing compound, and the grid structure body includes a conductive gel, and the phosphorus-containing compound is filled in the grids of the grid-like structure body. The above technical solution reduces the resistance of the negative electrode plate through the conductive gel contained in the grid-like structure body of the conductive layer, thereby improving its electrical conductivity. Moreover, the conductive gel can also absorb moisture to delay the dissolution rate of the SEI film, thereby improving the stability of the SEI. In addition, the phosphorus-containing compound is filled in the grids of the grid structure body, and after dissolution, it will react with the electrolyte and lithium ions to form an insoluble substance, and the insoluble substance can be used as a component of the SEI film, so that the dissolution rate of the SEI film can be further delayed to improve its stability. Therefore, the SEI film in the lithium battery cell provided by the embodiment of the present invention has good stability, which helps to improve the cycle performance and service life of the battery.

[0022] The above description is only an overview of the technical solutions of this specification. In order to be able to understand the technical means of this specification more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features and advantages of this specification more obvious and understandable, the following specifically illustrates the specific embodiments of this specification. Specific Embodiments

[0023] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a specific range. The range defined in this way can include or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, ranges of 60-110 and 80-120 are also contemplated. In addition, if the minimum range values of 1 and 2 are listed, and if the maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present invention, unless otherwise specified, the numerical range "a-b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been fully listed herein, and "0-5" is only an abbreviated representation of these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0024] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present invention.

[0025] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present invention.

[0026] Unless otherwise specified, all steps of the present invention can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out sequentially, or can also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method further includes step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b) and (c), or can also include steps (a), (c) and (b), or can also include steps (c), (a) and (b), etc.

[0027] Unless otherwise specified, the terms "comprising" and "including" mentioned in the present invention are open-ended and can also be closed-ended. For example, the "comprising" and "including" can mean that other components not listed can also be included or comprised, or can only include or comprise the listed components.

[0028] Unless otherwise specified, the term "or" in the present invention is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) while B is true (or exists); or both A and B are true (or exist).

[0029] Unless otherwise indicated, the terms used in the present invention have the well-known meanings commonly understood by those skilled in the art.

[0030] Unless otherwise specified, the numerical values of the various parameters mentioned in the present invention can be determined by various commonly used testing methods in the art. For example, they can be determined according to the testing methods given in the embodiments of the present invention.

[0031] In an embodiment of the present invention, a lithium battery cell generally includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The separator is disposed between the positive electrode plate and the negative electrode plate to separate the positive electrode plate and the negative electrode plate, and at the same time, allows active ions to pass through. During the production process of the lithium battery cell, battery formation is a key step in the battery production process, aiming to activate the positive and negative electrode materials inside the battery cell through charge and discharge cycles, and form a protective film on the surfaces of the positive and negative electrode plates. This protective film helps to improve the cycle performance and service life of the battery. Among them, the protective film formed on the surface of the negative electrode plate can be called a solid electrolyte interface film (Solid Electrolyte Interface, abbreviated as SEI film). During the subsequent use of the battery, some components in the SEI film will react with water to produce hydrofluoric acid, resulting in damage to the SEI film, thereby reducing the stability of the SEI film.

[0032] In order to improve the stability of the SEI film, in the related art, the composition of the electrolyte is usually improved to adjust the composition of the SEI film formed by it, so as to reduce the degree of damage caused by moisture. However, this is still insufficient to improve the stability of the SEI film during the use of the battery.

[0033] In view of this, an embodiment of the present invention provides a lithium battery cell, which absorbs moisture through the conductive gel contained in the grid-like structure in the conductive layer to delay the dissolution rate of the SEI film, thereby achieving the improvement of the stability of the SEI.

[0034] Next, the technical solutions of the embodiments of the present invention will be described in detail.

[0035] Lithium battery cell

[0036] In a first aspect, an embodiment of the present invention provides a lithium battery cell.

[0037] The lithium battery cell includes a negative electrode plate. The negative electrode plate includes a negative current collector, a negative active material layer, and a conductive layer. The negative active material layer is disposed on the surface of the negative current collector, and the conductive layer is disposed on the surface of the negative active material layer away from the negative current collector. The conductive layer includes a grid-like structure and a phosphorus-containing compound, and the grid structure includes a conductive gel, and the phosphorus-containing compound is filled in the grids of the grid-like structure.

[0038] In an embodiment of the present invention, the negative current collector has two surfaces opposite to each other in its own thickness direction, and the negative active material layer is disposed on any one or both of the two opposite surfaces of the negative current collector.

[0039] The lithium battery cell provided by the embodiment of the present invention reduces the resistance of the negative electrode sheet through the conductive gel contained in the grid-like structure in the conductive layer, thereby improving its conductivity. Moreover, the conductive gel can also absorb moisture to delay the dissolution rate of the SEI film, thereby improving the stability of the SEI. In addition, the phosphorus-containing compound is filled in the grid of the grid structure, and after dissolution, it reacts with the electrolyte and lithium ions to form an insoluble substance, which can be used as a component of the SEI film, thereby further delaying the dissolution rate of the SEI film to improve its stability. Therefore, the SEI film in the lithium battery cell provided by the embodiment of the present invention has good stability, which helps to improve the cycle performance and service life of the battery.

[0040] The embodiment of the present invention further regulates the conductive layer, which can further improve the stability of the SEI film.

[0041] In some embodiments, the size of the grid in the grid-like structure is 0.01 mm - 0.1 mm, which can further form ion channels with appropriate sizes and further reduce the damage degree of water to the SEI film.

[0042] In the above embodiments, the size of the grid refers to the distance between the two opposite sides of the grid.

[0043] Exemplarily, the size of the grid in the grid-like structure can be 0.01 mm, 0.015 mm, 0.02 mm, 0.025 mm, 0.03 mm, 0.035 mm, 0.04 mm, 0.045 mm, 0.05 mm, 0.055 mm, 0.06 mm, 0.065 mm, 0.07 mm, 0.075 mm, 0.08 mm, 0.085 mm, 0.09 mm, 0.095 mm, 0.1 mm or the range composed of any two of the above values.

[0044] In some embodiments, the conductive gel includes a conductive filler and a gel, and the conductive filler is doped into the gel to form a conductive gel. Among them, the mass ratio of the conductive filler to the gel is 1:(10 - 20), which can further reduce the resistance of the negative electrode sheet and enhance the water absorption of the conductive layer, thereby further reducing the damage degree of the SEI film by water.

[0045] Exemplarily, the mass ratio of the conductive filler to the gel can be 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20 or the range composed of any two of the above values.

[0046] In some embodiments, the conductive filler includes at least one of carbon nanotubes, conductive polymers, and graphene.

[0047] In some embodiments, the gel includes a hydrophilic porous gel. Optionally, the hydrophilic porous gel can be a polyacrylamide gel, a polyacrylic acid gel, a sodium polyacrylate gel, a polyvinyl alcohol gel, or a chitosan gel.

[0048] In some embodiments, the thickness of the conductive layer is 50 nm - 200 nm, which can help improve the energy density of a single lithium battery cell.

[0049] Exemplarily, the thickness of the conductive layer can be 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, 150 nm, 155 nm, 160 nm, 165 nm, 170 nm, 175 nm, 180 nm, 185 nm, 190 nm, 195 nm, 200 nm, or a range composed of any two of the above values.

[0050] In some embodiments, the phosphorus-containing compound includes at least one of elemental phosphorus, metal phosphides, and phosphates.

[0051] Optionally, the metal phosphide can be at least one of iron phosphide, manganese phosphide, or zinc phosphide.

[0052] In the embodiments of the present invention, the negative electrode current collector generally uses a metal foil or a composite current collector. Exemplarily, the negative electrode current collector uses a metal foil, and the metal foil can be a copper foil or an aluminum foil.

[0053] In the embodiments of the present invention, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material can be the negative electrode active material well-known in the art for a single lithium battery cell. Exemplarily, the negative electrode active material can include at least one of natural graphite, soft carbon, artificial graphite, hard carbon, and silicon-based materials. Optionally, the silicon-based material can include at least one of a silicon-carbon composite, a silicon alloy material, a silicon oxide, and a silicon nitride composite.

[0054] In some embodiments, the negative electrode active material can include at least one of artificial graphite and natural graphite. Based on the total mass of the negative electrode active material layer, the total mass content of artificial graphite and / or natural graphite is 80% - 95%.

[0055] Exemplarily, the negative electrode active material is artificial graphite, and the mass content of the artificial graphite can be 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, or a range composed of any two of the above values.

[0056] In some embodiments, the negative electrode active material layer may further include a conductive agent and / or a binder, wherein there are no special restrictions on the types of the conductive agent and the binder in the embodiments of the present invention.

[0057] Exemplarily, the above-mentioned conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, and Ketjen black. In some embodiments, based on the total mass of the negative electrode active material layer, the mass percentage content of the conductive agent is less than or equal to 6%.

[0058] Exemplarily, the binder may include at least one of polyacrylic acid (PAA), polymethacrylic acid (PMAA), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, based on the total mass of the negative electrode active material layer, the mass percentage content of the binder is less than or equal to 4%.

[0059] In some embodiments, the negative electrode active material layer may further include other additives, such as thickeners, etc.

[0060] In some embodiments, based on the total mass of the negative electrode active material layer, the mass percentage content of other additives is less than or equal to 3%.

[0061] In some embodiments, the lithium battery monomer further includes a positive electrode plate, which includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector and including a positive electrode active material.

[0062] In the above embodiments, the positive electrode current collector has two surfaces opposite to each other in its own thickness direction, and the positive electrode active material layer is provided on any one or both of the two opposite surfaces of the positive electrode current collector.

[0063] The positive electrode active material layer includes a positive electrode active material, which generally uses a positive electrode active material well-known in the art for lithium battery monomers.

[0064] Exemplarily, the positive electrode active material may include lithium nickel cobalt manganese oxide, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese phosphate, etc.

[0065] In some embodiments, based on the total mass of the positive electrode active material layer, the mass content of lithium iron phosphate is 85%-95%.

[0066] Exemplarily, the mass content of lithium iron phosphate may be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95% or a range composed of any two of the above values.

[0067] In some embodiments, the positive electrode active material layer may include a conductive agent and / or a binder. There are no particular limitations on the types of the conductive agent and the binder in the embodiments of the present invention.

[0068] Exemplarily, the conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, and Ketjen black. In some embodiments, based on the total mass of the positive electrode active material layer, the mass percentage content of the conductive agent is less than or equal to 6%.

[0069] Exemplarily, the binder may include at least one of polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE). In some embodiments, based on the total mass of the positive electrode active material layer, the mass percentage content of the binder is less than or equal to 4%.

[0070] In some embodiments, the positive electrode current collector generally uses a metal foil or a composite current collector. Exemplarily, the positive electrode current collector uses a metal foil, and the metal foil may be a copper foil or an aluminum foil.

[0071] The positive electrode active material layer is generally formed by coating a positive electrode active paste on the positive electrode current collector and drying and cold pressing it. Among them, the positive electrode active paste is formed by dispersing the positive electrode active material, the conductive agent, the binder, and optionally other additives in a solvent and stirring evenly.

[0072] In some embodiments, the lithium battery cell further includes a separator. There are no special limitations on the type of the separator in the embodiments of the present invention, and a separator well-known in the art for lithium battery cells can be used.

[0073] Exemplarily, the material of the separator may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0074] In some embodiments, the lithium battery cell further includes an electrolyte. Exemplarily, the electrolyte may include a lithium salt, and the lithium salt may further include at least one of lithium hexafluorophosphate LiPF6 and lithium bis(fluorosulfonyl)imide LiFSI.

[0075] In some embodiments, the solvent may include one or more of ethyl methyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, methyl formate, ethylene carbonate, propyl propionate, propylene carbonate, diethyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, and ethyl propionate.

[0076] In some embodiments, the lithium battery cell further includes an outer package for encapsulating the above electrode assembly and the electrolyte.

[0077] In the above embodiments, the outer package can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0078] The embodiments of the present invention do not particularly limit the shape of the lithium battery monomer, which can be cylindrical, square, or any other shape.

[0079] Manufacturing method of lithium battery monomer

[0080] In a second aspect, the embodiments of the present invention provide a manufacturing method of the above lithium battery monomer, including:

[0081] Mix the raw materials of the negative electrode active material layer to form a negative electrode active paste;

[0082] Coat the negative electrode active paste on the surface of the negative electrode current collector and dry it to form a negative electrode active material layer on the surface of the negative electrode current collector;

[0083] Mix part of the raw materials of the conductive layer to form a conductive paste, place the conductive paste in a mold, and form a grid-like structure after drying;

[0084] Bond the grid-like structure to the surface of the negative electrode active material layer away from the negative electrode current collector;

[0085] Disperse the phosphorus-containing compound in a solvent to form a phosphorus-containing paste;

[0086] Fill the phosphorus-containing paste into the grids in the grid-like structure, and form a conductive layer after drying to obtain a negative electrode plate;

[0087] Assemble the positive electrode plate, the separator, the negative electrode plate and the electrolyte to form a lithium battery monomer.

[0088] During the assembly process, the positive electrode plate, the separator, and the negative electrode plate can be formed into an electrode assembly through a winding process and / or a stacking process, place the electrode assembly in an outer package, inject the electrolyte after drying, and obtain the lithium battery monomer through processes such as vacuum packaging, standing, formation, and shaping.

[0089] Battery

[0090] In a third aspect, the embodiments of the present invention provide a battery, including the lithium battery monomer according to any one of the embodiments in the first aspect of the present invention.

[0091] In the present invention, a battery refers to a physical module including one or more lithium battery cells to provide electrical energy. For example, the battery mentioned in the present invention may include a battery module or a battery pack, etc. A battery generally includes a box for encapsulating one or more lithium battery cells. The box can prevent liquids or other foreign objects from affecting the charging or discharging of the lithium battery cells.

[0092] Exemplarily, the lithium battery cells of any embodiment in the first aspect of the present invention can be assembled into a battery module. The number of lithium battery cells contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0093] In addition, the above battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0094] Electric device

[0095] In a fourth aspect, an embodiment of the present invention provides an electric device, which includes the battery of any embodiment in the third aspect of the present invention. This battery can be used as the power source of the electric device or as the energy storage unit of the electric device. The electric device can be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship, a satellite, an energy storage system, etc.

[0096] The following embodiments more specifically describe the content disclosed in the present invention. These embodiments are only for illustrative purposes, because various modifications and changes within the scope of the present invention are obvious to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized according to conventional methods and can be used directly without further treatment, and all instruments used in the embodiments are commercially available.

[0097] Example 1

[0098] (1) Preparation of the positive electrode sheet

[0099] Mix lithium iron phosphate particle positive electrode active material, carbon black, and PVDF in a mass ratio of 95:3:2 in an appropriate amount of N-methylpyrrolidone (NMP) and stir well to form a uniform positive electrode active material slurry; coat the positive electrode active material slurry on the surface of the positive electrode current collector aluminum foil, and after drying, cold pressing, and die cutting, obtain the positive electrode sheet.

[0100] (2) Preparation of the negative electrode sheet

[0101] Artificial graphite, acetylene black, and carboxymethyl chitosan (CMCS) were fully stirred in an appropriate amount of deionized water according to a mass ratio of 93:5:2 to form a uniform negative electrode active material slurry; the negative electrode active material slurry was coated on the surface of the negative electrode current collector copper foil, and after drying, cold pressing, and die-cutting, a negative electrode active material layer was formed on the surface of the copper foil;

[0102] Single-walled carbon nanotubes and chitosan powder were added to a dilute formic acid solution (volume ratio, formic acid:water = 1:100) according to a mass ratio of 1:10 to prepare a gel containing 30 mg / mL of chitosan, which was placed on a magnetic stirrer and stirred for 25 min to dissolve the chitosan, obtaining a conductive slurry. The conductive slurry was placed in a grid mold, and after drying, a grid-like structure with an average grid size of about 0.015 mm was formed;

[0103] The grid-like structure was bonded to the surface of the negative electrode active material layer away from the negative electrode current collector;

[0104] 2 g of manganese phosphide, 100 mL of polyvinyl alcohol (model PVA124, purchased from Guangzhou Songbai Chemical Co., Ltd.), and 200 mL of water were mixed to form a phosphorus-containing slurry;

[0105] The phosphorus-containing slurry was filled into the grids of the grid-like structure, and after drying, a conductive layer was formed to obtain a negative electrode plate, where the thickness of the conductive layer was 50 nm;

[0106] (3) Preparation of the electrolyte

[0107] In an inert atmosphere glove box with water and oxygen both less than 0.3 ppm, methyl propionate, ethyl methyl carbonate, and diethyl carbonate were mixed according to a ratio of 2:5:1 to form a basic electrolyte, and then fully dried lithium hexafluorophosphate (LiPF6) was added and stirred at room temperature for 40 min to completely dissolve lithium hexafluorophosphate and the basic electrolyte in a mass ratio of 1:3, obtaining the electrolyte.

[0108] (4) Separator

[0109] A polyethylene film was used as the separator.

[0110] (5) Preparation of the lithium battery cell

[0111] The above positive electrode plate, separator, and negative electrode plate were stacked in sequence and formed into an electrode assembly through a winding process. Then, the electrode assembly was placed in an aluminum shell, baked at 75 °C to remove moisture, and then the above electrolyte was injected and sealed; finally, through processes such as standing, formation, and shaping, the lithium battery cell of this embodiment was obtained.

[0112] Example 2

[0113] The difference from Example 1 is that carbon nanotubes and sodium polyacrylate are mixed to form a conductive paste.

[0114] Example 3

[0115] The difference from Example 1 is that the mass ratio of carbon nanotubes to chitosan powder is 1:15.

[0116] Example 4

[0117] The difference from Example 1 is that the mass ratio of carbon nanotubes to chitosan powder is 1:20.

[0118] Example 5

[0119] The difference from Example 1 is that manganese phosphide is used instead of zinc phosphide.

[0120] Comparative Example 1

[0121] The difference from Example 1 is that the conductive layer does not contain gel.

[0122] Comparative Example 2

[0123] The difference from Example 1 is that the conductive layer does not contain phosphorus-containing compounds.

[0124] Test section

[0125] Cycling performance test:

[0126] The lithium battery monomers prepared in Examples 1-5 and Comparative Examples 1-2 were respectively placed in an environment at 25 °C, charged at a constant current of 0.2C to 3.6V, and then discharged at 0.2C to 2.0V, and repeated 3 times. The third discharge capacity Q1 was extracted as the initial state capacity calibration value, and then the cycling performance was tested by cycling 1000 times at 1C / 1C. After the end of the 1000th cycle, the 1000-cycle discharge capacity Q2 was measured. The capacity retention rate a = Q2 / Q1 was calculated based on the initial state capacity calibration value Q1 discharge capacity and the 1000-cycle discharge capacity. The test results are shown in Table 1.

[0127] Serial number Capacity retention rate (%) after 1000 cycles at 25℃ and 1C Example 1 96.1％ Example 2 97.3％ Example 3 97.5％ Example 4 95.2％ Example 5 98.4％ Comparative example 1 90.2％ Comparative example 2 91.0％

[0128] As can be seen from comparing the test results of Examples 1-5 and Comparative Examples 1-2 in Table 1, in the lithium battery monomer provided by the present invention, the resistance of the negative electrode sheet is reduced by the conductive gel contained in the grid-like structure in the conductive layer, thereby improving its conductivity. Moreover, the conductive gel can also absorb moisture to delay the dissolution rate of the SEI film, thereby improving the stability of the SEI. In addition, the phosphorus-containing compound is filled in the grid of the grid structure, and after dissolution, it will react with the electrolyte and lithium ions to form an insoluble substance, which can be used as a constituent of the SEI film, so as to further delay the dissolution rate of the SEI film to improve its stability. Therefore, the SEI film in the lithium battery monomer provided by the embodiment of the present invention has good stability, which helps to improve the cycle performance and service life of the battery. Comparative Example 1 does not contain gel, and its capacity retention rate after 1000 cycles at 25°C and 1C is significantly lower than that of Examples 1-5; Comparative Example 2 does not contain phosphorus-containing compound, and its capacity retention rate after 1000 cycles at 25°C and 1C is also significantly lower than that of Examples 1-5.

[0129] Finally, it should be noted that the above experimental examples are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing experimental examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing experimental examples, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the experimental examples of the present invention.

Claims

1. A lithium battery cell, characterized in that, Comprising: A negative electrode plate, which includes a negative electrode current collector, a negative electrode active material layer, and a conductive layer. The negative electrode active material layer is disposed on the surface of the negative electrode current collector, and the conductive layer is disposed on the surface of the negative electrode active material layer away from the negative electrode current collector. The conductive layer includes a grid-like structure body and a phosphorus-containing compound, and the grid structure body includes a conductive gel, and the phosphorus-containing compound is filled in the grids of the grid-like structure body; The size of the grids in the grid-like structure body is 0.01 mm - 0.1 mm; The conductive gel includes a conductive filler and a gel, and the conductive filler is doped into the gel to form a conductive gel. Among them, the mass ratio of the conductive filler to the gel is 1:(10 - 20); The gel includes a hydrophilic porous gel, and the porous gel is a chitosan gel or a sodium polyacrylate gel; The conductive filler is a carbon nanotube; The phosphorus-containing compound is manganese phosphide or zinc phosphide; The thickness of the conductive layer is 50 nm - 200 nm; The method for disposing the conductive layer on the surface of the negative electrode active material layer away from the negative electrode current collector includes: mixing some raw materials of the conductive layer to form a conductive paste, placing the conductive paste in a mold, and drying to form a grid-like structure body; bonding the grid-like structure body to the surface of the negative electrode active material layer away from the negative electrode current collector; dispersing the phosphorus-containing compound in a solvent to form a phosphorus-containing paste; filling the phosphorus-containing paste into the grids of the grid-like structure body, and drying to form a conductive layer.

2. A manufacturing method of a single lithium battery cell as claimed in claim 1, characterized in that, Comprising: Mixing the raw materials of the negative electrode active material layer to form a negative electrode active paste; Coating the negative electrode active paste on the surface of the negative electrode current collector and drying to form a negative electrode active material layer on the surface of the negative electrode current collector; Mixing some raw materials of the conductive layer to form a conductive paste, placing the conductive paste in a mold, and drying to form a grid-like structure body; Bonding the grid-like structure body to the surface of the negative electrode active material layer away from the negative electrode current collector; Dispersing the phosphorus-containing compound in a solvent to form a phosphorus-containing paste; Filling the phosphorus-containing paste into the grids of the grid-like structure body, and drying to form a conductive layer to obtain a negative electrode plate.

3. A battery, characterized in that, Including the lithium battery monomer of claim 1.

4. An electrical device, characterized in that, Including the battery of claim 3.