Negative pole piece, preparation method thereof and lithium battery

Abstract

The invention belongs to the technical field of batteries, and discloses a negative pole piece, a preparation method thereof and a lithium battery. The negative pole piece comprises a current collector and a lithium-loving active layer, the lithium-loving active layer is arranged on at least one side of the current collector, the lithium-loving active layer comprises a lithium-loving active site, and a functional group is grafted on the lithium-loving active site. The functional group comprises at least one of a silicon-containing functional group, a nitrogen-containing functional group, a sulfur-containing functional group and a boron-containing functional group. According to the negative pole piece provided by the invention, the rate capability, the cycling stability and the safety performance of the lithium battery can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a negative electrode plate and a preparation method thereof, and a lithium battery. Background Art

[0002] Lithium-ion batteries have become the first choice for consumer electronic batteries and new energy vehicle power batteries due to their advantages such as high energy density, long cycle life and no memory effect. However, the graphite or silicon-doped negative electrodes used in existing lithium-ion batteries have low specific capacity, which limits the further improvement of their energy density.

[0003] The metal lithium negative electrode has a specific capacity of 3860mAh / g. Its use will greatly improve the energy density of lithium batteries. However, the dendrite problem, side reaction problem with the electrolyte and volume expansion effect of the metal lithium negative electrode will affect the rate performance, cycle stability and safety performance of the lithium battery, limiting the commercial application of the metal lithium negative electrode. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, one object of the present invention is to provide a negative electrode plate and a preparation method thereof, and a lithium battery. The negative electrode plate provided in the present application can improve the rate performance, cycle stability and safety performance of the battery.

[0005] In the first aspect of the present invention, the present invention proposes a negative electrode plate. According to an embodiment of the present invention, the negative electrode plate includes: a current collector and a lithium-philic active layer, the lithium-philic active layer is arranged on at least one side of the current collector, the lithium-philic active layer includes lithium-philic active sites, and functional groups are grafted on the lithium-philic active sites, and the functional groups include at least one of silicon-containing functional groups, nitrogen-containing functional groups, sulfur-containing functional groups and boron-containing functional groups.

[0006] According to the negative electrode plate of the above embodiment of the present invention, the current collector serves as a basic support, and the lithium-philic active layer is arranged on at least one side of the current collector. Through the action of chemical bonds, at least one of the silicon-containing functional group, the nitrogen-containing functional group, the sulfur-containing functional group and the boron-containing functional group can be stably grafted on the lithium-philic active site. The grafting of the functional group can effectively prevent the agglomeration of the lithium-philic active site, ensure that the lithium-philic active site can be evenly distributed on the current collector in a dispersed state, and then induce the lithium metal to be evenly dispersed on the current collector; the grafting of the functional group can also firmly anchor the lithium-philic active site on the surface of the current collector, and preferentially realize uniform lithium deposition at the active lithium-philic site on the current collector side during the battery cycle, which is beneficial to maintaining the cycle stability of the battery; the lithium-philic active site grafted with the functional group can form a lithium metal nucleation site, inducing lithium ions to be directional deposited along the (110) crystal plane, thereby inhibiting the formation of lithium dendrites. Disordered growth is beneficial to improving the safety performance and cycle stability of lithium batteries; when functional groups are grafted on the lithium-philic active sites, the electronic structure and chemical properties of the current collector surface can also be adjusted, so that the interaction between the current collector surface and lithium metal changes, which helps to promote the lattice matching of the low potential energy crystal planes between the current collector surface and lithium metal, making the deposition of lithium on the current collector surface more orderly and evenly distributed on the current collector. Uniform lithium deposition can improve the cycle stability and safety of lithium batteries; and when the lattice matching between the current collector surface and lithium metal is improved, the nucleation and growth of lithium ions on the current collector surface become easier, reducing the potential energy of lithium nucleation and growth, which is beneficial to improving the safety performance of lithium batteries; in addition, the introduction of functionalized functional groups can improve the unit effective area and electrochemical activity of the active site with the conjugated structure, and improve the rate performance of the battery. Therefore, the negative electrode plate provided by the present application can improve the rate performance, cycle stability and safety performance of lithium batteries.

[0007] In addition, the negative electrode sheet according to the above embodiment of the present invention may also have the following additional technical features:

[0008] In some embodiments of the present invention, the thickness of the lithium-philic active layer is 0.2 nm-60 μm, preferably 0.2 nm-50 μm, thereby improving the rate performance, cycle stability and safety performance of the lithium battery.

[0009] In some embodiments of the present invention, the mass of the functional group accounts for 1%-20% of the mass of the lithium-philic active site; the mass of the functional group is calculated based on the mass of the substance providing the functional group. Thus, the cycle performance and safety performance of the lithium battery can be improved.

[0010] In some embodiments of the present invention, the substance providing the functional group includes at least one of amine compounds, silicon fluoride, nitrogen-containing heterocyclic compounds, nitrile compounds, nitro compounds, thienyl-containing compounds, and furanyl thiocarboxylates. Thus, the aggregation of the lithium-philic active sites can be prevented by forming chemical bonds or hydrogen bonds with the lithium-philic active sites.

[0011] In some embodiments of the present invention, the amine compound includes at least one of dopamine, aromatic amine, sulfonylated amine, and halogenated aromatic amine.

[0012] In some embodiments of the present invention, the nitrogen-containing heterocyclic compound includes thiourea.

[0013] In some embodiments of the present invention, the Dv50 particle size of the lithium-philic active site is 0.1 nm-500 nm, preferably 0.2 nm-200 nm. Thus, the safety performance, rate performance and cycle performance of the lithium battery can be improved.

[0014] In some embodiments of the present invention, the morphology of the lithium-philic active site includes at least one of a one-dimensional point, a one-dimensional rod, a two-dimensional sheet, and a three-dimensional structure, thereby improving the safety performance, rate performance, and cycle performance of the lithium battery.

[0015] In some embodiments of the present invention, the lithium-philic active sites include at least one of magnesium, zinc, nickel, aluminum, silver, gold, molybdenum, lead, tin, bismuth, palladium, ruthenium, iridium, platinum, cerium, indium, silicon, carbon, and their respective oxides, sulfides, halides, and nitrides. Thus, the safety performance, rate performance, and cycle performance of the lithium battery can be improved.

[0016] In some embodiments of the present invention, the lithium-philic active layer further comprises a first conductive material and a binder, thereby improving the charge and discharge efficiency and rate performance of the battery, and facilitating the improvement of the cycle stability of the lithium battery.

[0017] In some embodiments of the present invention, the mass ratio of the first conductive material to the lithium-philic active site is (1-99): 1. Thus, a dense conductive network can be formed in the lithium-philic active layer, which is conducive to the rapid transmission of electrons in the negative electrode sheet, reduces the internal resistance of the battery, and improves the rate performance and charge and discharge efficiency of the lithium battery.

[0018] In some embodiments of the present invention, the first conductive material includes at least one of conductive graphite, conductive carbon black, acetylene black, ketjen black, carbon fiber, single-walled carbon nanotube, multi-walled carbon nanotube, polyethylene dioxythiophene, polystyrene sulfonic acid, lithium polystyrene sulfonate, sodium polystyrene sulfonate, graphene, fullerene, silicon carbide, calcium carbide, boron carbide, vanadium carbide, magnesium carbide, titanium carbide, zirconium carbide, tantalum carbide, tungsten carbide and niobium carbide. Thus, it can interact with the lithium-philic active sites to form a stable composite material, which can improve the conductivity of the negative electrode sheet.

[0019] In some embodiments of the present invention, the negative electrode plate further comprises a lithium metal layer, and the lithium metal layer is disposed on a side of the lithium-philic active layer away from the current collector, thereby guiding lithium ions to deposit on the lithium metal layer in an orderly manner, reducing the formation of lithium dendrites, and thus achieving a higher capacity utilization rate.

[0020] In some embodiments of the present invention, the negative electrode plate further comprises an intermediate composite layer, and the intermediate composite layer is arranged on the side of the lithium-philic active layer away from the current collector. Thus, there are sufficient positions for reversible insertion and removal of lithium metal during the charge and discharge process, thereby improving the capacity of the battery, preventing the disordered growth of lithium dendrites, promoting the uniform distribution of lithium ions, and improving the cycle performance of the battery.

[0021] In some embodiments of the present invention, the thickness of the intermediate composite layer is 10 μm-100 μm. As a result, the volume of lithium metal changes during the charge and discharge process, and the elastic structure of the intermediate composite layer can adapt to the volume change of lithium metal, reduce the expansion and contraction of the negative electrode sheet, and improve the cycle life of the battery.

[0022] In some embodiments of the present invention, the intermediate composite layer includes at least one of reticulated glassy carbon, etherified reticulated cellulose, cellulose, lignin, ether lignin, chitosan, alginate, lithium alginate, sodium alginate, graphite, graphene, hard carbon, soft carbon, fullerene, elemental silicon, silicon-oxygen material, silicon-carbon material, silicon-nitrogen material, silicon-based alloy, elemental tin, tin-based alloy, lithium metal, lithium-based alloy, lithium-titanium oxide, transition metal oxide, transition metal sulfide, second conductive material, porous carbon material, carbon molecular sieve, mesoporous material, metal organic framework compound, covalent organic framework material, zeolite imidazolate framework structure material, 6-amino-1-hexanol-polyacrylic acid, hydroxyethylethylenediamine-polyacrylic acid, diglycolamine-polyacrylic acid ion cross-linked polymer, 5-amino-1-pentanol-polyacrylic acid, 4-amino-1-butanol-polyacrylic acid, N,N-bis(2-hydroxyethyl)ethylenediamine-polyacrylic acid and solid electrolyte.

[0023] In some embodiments of the present invention, the transition metal oxide includes a tin oxide compound.

[0024] In some embodiments of the present invention, the second conductive material includes at least one of conductive graphite, conductive carbon black, acetylene black, Ketjen black, carbon fiber, single-walled carbon nanotubes, multi-walled carbon nanotubes, polyethylene dioxythiophene, polystyrene sulfonic acid, lithium polystyrene sulfonate, sodium polystyrene sulfonate, graphene, fullerene, silicon carbide, calcium carbide, boron carbide, vanadium carbide, magnesium carbide, titanium carbide, zirconium carbide, tantalum carbide, tungsten carbide and niobium carbide.

[0025] In some embodiments of the present invention, the negative electrode plate further comprises a solid electrolyte layer, and the solid electrolyte layer is disposed on a side of the intermediate composite layer away from the lithium-philic active layer. Thus, a specific ion transmission channel can be provided to promote the rapid migration of lithium ions between the negative electrode plate and other parts of the battery, which helps to improve the charge and discharge efficiency and rate performance of the battery, so that the battery can complete charging or release more energy in a shorter time.

[0026] In the second aspect of the present invention, the present invention proposes a method for preparing the above-mentioned negative electrode sheet. According to an embodiment of the present invention, the method comprises: preparing the lithium-philic active layer on at least one side of the current collector, the lithium-philic active layer comprises a lithium-philic active site, and a functional group is grafted on the lithium-philic active site, and the functional group comprises at least one of a silicon-containing functional group, a nitrogen-containing functional group, a sulfur-containing functional group and a boron-containing functional group. Thus, the rate performance, cycle performance and safety performance of the battery can be improved.

[0027] In some embodiments of the present invention, the step of preparing the lithium-philic active layer on at least one side of the current collector includes: mixing a lithium-philic active site precursor, a functional group precursor, a reducing agent, a conductive material, a binder, a dispersant and a solvent, and performing a reduction reaction to obtain a first precursor solution; and introducing the first precursor solution into at least one side of the current collector to form the lithium-philic active layer. Thus, the safety performance and cycle stability of the lithium battery can be improved.

[0028] In some embodiments of the present invention, the step of preparing the lithium-philic active layer on at least one side of the current collector includes: mixing a lithium-philic active site precursor, a functional group precursor, a reducing agent, a conductive material, a binder, a dispersant and a solvent, performing a first reduction reaction to obtain a second precursor solution; introducing the second precursor solution into at least one side of the current collector, performing a second reduction reaction to form the lithium-philic active layer. Thus, the safety performance and cycle stability of the lithium battery can be improved.

[0029] In some embodiments of the present invention, the mass proportion of the binder is 1%-10% based on the total mass of the first precursor solution or based on the total mass of the second precursor solution. Thus, the lithium-philic active sites, conductive materials, etc. can be firmly combined with the current collector to prevent them from falling off and being damaged during the battery charging and discharging process, which is beneficial to improving the cycle stability of the lithium battery.

[0030] In some embodiments of the present invention, the lithium-philic active site precursor includes at least one of a soluble magnesium source, a soluble zinc source, a soluble nickel source, a soluble aluminum source, a soluble silver source, a soluble gold source, a soluble molybdenum source, a soluble lead source, a soluble tin source, a soluble bismuth source, a soluble palladium source, a soluble ruthenium source, a soluble iridium source, a soluble platinum source, a soluble cerium source, a soluble indium source, a soluble silicon source, and a soluble carbon source. Thus, the metal element after reduction of the lithium-philic active site precursor can react with lithium to form an alloy or have a specific chemical adsorption effect, showing good lithium affinity.

[0031] In some embodiments of the present invention, the soluble silver source includes at least one of silver nitrate, silver sulfate, silver fluoride, silver perchlorate and silver acetate.

[0032] In some embodiments of the present invention, the reducing agent includes at least one of zinc powder, glucose, hydrazine hydrate, dodecyltetraethylene glycol ether, dimethylamine-borane, polyamide, lithium citrate and sodium citrate.

[0033] In some embodiments of the present invention, the dispersant includes at least one of polyvinyl pyrrolidone, aniline, sodium naphthalene formaldehyde sulfonate, dihexadecyl pyridinium dithiophosphate, polyacrylic acid, cysteine ​​and polyvinyl epoxy nonphenyl ether.

[0034] In some embodiments of the present invention, the introduction method includes at least one of concave roller, coating, spraying and chemical vapor deposition. Thus, the uniform distribution of lithium-philic active sites can be achieved, which can ensure the uniform transmission and storage of lithium ions in the negative electrode sheet, reduce local polarization and capacity attenuation, and help improve the charge and discharge efficiency, rate performance and cycle stability of the battery.

[0035] In some embodiments of the present invention, the temperature of the first reduction reaction is 80° C.-300° C. Thus, the battery rate performance, cycle performance and safety performance can be improved.

[0036] In some embodiments of the present invention, the time of the first reduction reaction is 3h-10h, thereby improving the battery rate performance, cycle performance and safety performance.

[0037] In some embodiments of the present invention, the second reduction reaction comprises at least one of liquid phase reduction and ultraviolet reduction.

[0038] In some embodiments of the present invention, the method further comprises: preparing the lithium metal layer on the side of the lithium-philic active layer away from the current collector. Thus, the overall capacity of the battery can be significantly increased, and when the battery is charged and discharged, the lithium metal layer can provide a large amount of lithium ions to participate in the reaction, thereby improving the energy storage capacity of the battery.

[0039] In some embodiments of the present invention, the preparation method of the lithium metal layer includes at least one of electrochemical deposition, evaporation and continuous rolling. This is conducive to the rapid transmission of lithium ions, improves the charge and discharge efficiency and rate performance of the battery, and can also reduce the situation of excessive local lithium ion concentration, reduce the risk of lithium dendrite formation, and help improve the safety performance and cycle stability of lithium batteries.

[0040] In some embodiments of the present invention, the temperature of the electrochemical deposition is -15°C-60°C, preferably 2°C-20°C. This is conducive to the uniform deposition of lithium metal on the surface of the lithium-philic active layer, helps to improve the quality and performance of the lithium metal layer, and reduces the generation of defects.

[0041] In some embodiments of the present invention, the method further comprises: preparing the intermediate composite layer on the side of the lithium-philic active layer away from the current collector. Thus, there are sufficient positions for reversible insertion and removal of lithium metal during the charge and discharge process, which increases the capacity of the battery, prevents the disordered growth of lithium dendrites, promotes the uniform distribution of lithium ions, and improves the cycle performance of the battery.

[0042] In some embodiments of the present invention, the method for preparing the intermediate composite layer includes at least one of coating and spraying.

[0043] In some embodiments of the present invention, the method further comprises: preparing a solid electrolyte layer on the side of the intermediate composite layer away from the lithium-philic active layer. Thus, the rapid migration of lithium ions between the negative electrode plate and other parts of the battery is promoted, which helps to improve the charge and discharge efficiency and rate performance of the battery, so that the battery can be charged or release more energy in a shorter time.

[0044] In the third aspect of the present invention, the present invention provides a lithium battery. According to an embodiment of the present invention, the lithium battery comprises the negative electrode sheet of the first aspect or the negative electrode sheet prepared by the method of the second aspect. The lithium battery has excellent safety performance, cycle performance and rate performance.

[0045] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0047] Figure 1 A schematic diagram of the battery structure prepared using the negative electrode sheet of the present application is shown.

[0048] Figure Number:

[0049] Negative electrode plate 10, current collector 1, lithium-philic active layer 2, intermediate composite layer 3, solid electrolyte layer 4. DETAILED DESCRIPTION

[0050] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0051] In the first aspect of the present invention, the present invention provides a negative electrode sheet 10. According to an embodiment of the present invention, referring to Figure 1 The negative electrode plate 10 includes a current collector 1 and a lithium-philic active layer 2 .

[0052] The current collector 1 plays an important role in basic support, electron transport and fixation of the lithium-philic active layer 2 in the negative electrode plate 10, and is a key component to ensure battery performance and stability. There is no special limitation on the type of the current collector 1, and those skilled in the art can select it as needed.

[0053] As an example, the current collector 1 includes but is not limited to at least one of copper foil, aluminum foil, stainless steel and a composite current collector.

[0054] As an example, the composite current collector includes an organic material substrate and an inorganic metal layer on the surface of the substrate, wherein the organic substrate material includes but is not limited to at least one of polyethylene terephthalate, polybutylene terephthalate, polystyrene and polypropylene, and the material of the inorganic metal layer on the surface includes but is not limited to at least one of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, gold and gold alloy.

[0055] According to an embodiment of the present invention, the lithium-philic active layer 2 is arranged on at least one side of the current collector 1, and the lithium-philic active layer 2 includes a lithium-philic active site, and a functional group is grafted on the lithium-philic active site, and the functional group includes at least one of a silicon-containing functional group, a nitrogen-containing functional group, a sulfur-containing functional group and a boron-containing functional group.

[0056] According to the negative electrode plate 10 of the above embodiment of the present invention, the current collector 1 serves as a basic support, and the lithium-philic active layer 2 is arranged on at least one side of the current collector 1. Through the action of chemical bonds, at least one of the silicon-containing functional group, the nitrogen-containing functional group, the sulfur-containing functional group and the boron-containing functional group can be stably grafted on the lithium-philic active site. The grafting of the functional group can effectively prevent the agglomeration of the lithium-philic active site, ensuring that the lithium-philic active site can be evenly distributed on the current collector 1 in a dispersed state; the grafting of the functional group can also firmly anchor the lithium-philic active site on the surface of the current collector 1, and preferentially realize uniform lithium deposition at the active lithium-philic site on the current collector side during the battery cycle, which is beneficial to maintaining the cycle stability of the battery; the lithium-philic active site grafted with the functional group can form a lithium metal nucleation site, inducing lithium ions to be directional deposited along the (110) crystal plane, thereby inhibiting the disordered growth of lithium dendrites, which is beneficial to improving the battery cycle stability. The safety performance and cycle stability of high lithium batteries; when the functional groups are grafted on the lithium-philic active sites, the electronic structure and chemical properties of the surface of the current collector 1 can be adjusted to change the interaction between the surface of the current collector 1 and the lithium metal, which helps to promote the lattice matching of the low potential energy crystal planes between the surface of the current collector 1 and the lithium metal, so that the deposition of lithium on the surface of the current collector 1 is more orderly and can be evenly distributed on the current collector 1. The uniform lithium deposition can improve the cycle stability and safety of the lithium battery; and when the lattice matching between the surface of the current collector 1 and the lithium metal is improved, the nucleation and growth of lithium ions on the surface of the current collector 1 become easier, reducing the potential energy of lithium nucleation and growth, which is beneficial to improving the safety performance of the lithium battery; in addition, the introduction of functionalized functional groups can improve the unit effective area and electrochemical activity of the active sites with the conjugated structure, and improve the rate performance of the battery. Therefore, the negative electrode plate 10 provided by the present application can improve the rate performance, cycle stability and safety performance of the lithium battery.

[0057] According to some embodiments of the present invention, the thickness of the lithium-philic active layer 2 is 0.2nm-60μm. For example, it can be 0.2nm, 10nm, 50nm, 100nm, 500nm, 900nm, 1μm, 5μm, 10μm, 20μm, 40μm, etc. By limiting the thickness of the lithium-philic active layer 2 to the above range, a uniform dispersion of atomic-level or nano-level active sites close to the current collector side is achieved within the preferred thickness range, and the agglomeration of active sites in the extension direction is prevented, providing space for the nucleation growth of ordered lithium deposition, improving rate performance and cycle stability, preventing the growth of lithium dendrites and the formation of dead lithium, and improving safety performance. Thus, the rate performance, cycle stability and safety performance of lithium batteries can be improved. Further, the thickness of the lithium-philic active layer 2 is preferably 0.2nm-50μm.

[0058] According to some embodiments of the present invention, the mass of the functional group accounts for 1%-20% of the mass of the lithium-philic active site, and the mass of the functional group is calculated based on the mass of the substance providing the functional group. For example, the mass of the functional group may account for 1%, 5%, 10%, 20%, etc. of the mass of the lithium-philic active site. By limiting the mass of the functional group to the mass of the lithium-philic active site within the above range, the grafting of the functional group can maintain the dispersed state of the lithium-philic active site through chemical bonds or steric hindrance, effectively prevent the agglomeration of the lithium-philic active site, improve the stability and reliability of the negative electrode sheet 10, and thus enhance the cycle performance of the lithium battery; the grafting of the functional group can induce uniform deposition of lithium ions, inhibit the growth of lithium dendrites, and help improve the safety performance of the lithium battery. Thus, the cycle performance and safety performance of the lithium battery can be improved.

[0059] According to some embodiments of the present invention, the substance providing the functional group includes at least one of amine compounds, silicon fluoride, nitrogen-containing heterocyclic compounds, nitrile compounds, nitro compounds, thiophene-containing compounds, and furanyl thiocarboxylates. The above-mentioned substance providing the functional group can prevent the agglomeration of the lithium-philic active sites by forming chemical bonds or hydrogen bonds with the lithium-philic active sites. As an example, the amine compound includes at least one of dopamine, aromatic amine, sulfonylated amine, and halogenated aromatic amine; the nitrogen-containing heterocyclic compound includes thiourea. Among them, aromatic amines can form π-π stacking effects with lithium-philic active sites, stabilize the active sites, prevent them from agglomerating during the cycle, help maintain the structural stability of the pole piece, and improve the cycle performance of the lithium battery; the above-mentioned substance providing the functional group can also provide specific functional groups, which can induce directional deposition of lithium ions, prevent disordered growth of lithium dendrites, and improve the safety performance of lithium batteries. For example, thiophene groups can form special coordination effects with lithium ions, guide lithium ions to uniformly nucleate and grow on the surface of the negative electrode current collector 1, and inhibit the disordered growth of lithium dendrites. This can improve the safety performance and cycle performance of the lithium battery.

[0060] According to some embodiments of the present invention, the Dv50 particle size of the lithium-philic active site is 0.1nm-500nm. For example, it can be 0.2nm, 0.5nm, 10nm, 50nm, 100nm, 200nm, 500nm, etc. By limiting the Dv50 particle size of the lithium-philic active site to the above range, highly dispersed active sites at the atomic or nanoscale are achieved within the preferred range, more lithium-philic active sites are provided, orderly preferential lithium deposition is achieved, rate performance and cycle stability are improved, lithium dendrite growth and the formation of dead lithium are prevented, and safety performance is improved. Thus, the safety performance, rate performance and cycle performance of lithium batteries can be improved. Furthermore, the Dv50 particle size of the lithium-philic active site is preferably 0.2nm-200nm.

[0061] It should be noted that the Dv50 particle size refers to the particle size corresponding to when the cumulative volume distribution percentage reaches 50%, which is measured with a laser particle size analyzer (such as Malvern Master Size 3000) or characterized by a high-resolution spherical aberration electron microscope with reference to the standard GB / T 19077-2016.

[0062] It should be noted that there is no particular limitation on the morphology of the lithium-philic active site, and those skilled in the art can flexibly select it as needed.

[0063] As an example, the morphology of the lithium-philic active site includes at least one of a one-dimensional point, a one-dimensional rod, a two-dimensional sheet, and a three-dimensional structure.

[0064] According to some embodiments of the present invention, the lithium-philic active sites include at least one of magnesium, zinc, nickel, aluminum, silver, gold, molybdenum, lead, tin, bismuth, palladium, ruthenium, iridium, platinum, cerium, indium, silicon, carbon and their respective oxides, sulfides, halides, and nitrides. The above-mentioned lithium-philic active sites can form alloys when reacting with lithium, have good lithium-philicity, make the adsorption and desorption of lithium ions on the surface of the negative electrode plate 10 easier, reduce the polarization degree of the battery, help improve the charge and discharge efficiency of the battery, reduce energy loss, and improve the safety performance of the lithium battery.

[0065] It should be noted that, taking "magnesium and its oxides, sulfides, halides, and nitrides" as an example, "magnesium and its oxides, sulfides, halides, and nitrides" refers to magnesium element, magnesium oxide, magnesium sulfide, magnesium halide, and magnesium nitride. The lithium-philic active sites may include at least one of magnesium element, magnesium oxide, magnesium sulfide, magnesium halide, and magnesium nitride. Of course, they may also include a combination of the above-mentioned magnesium-containing substances and at least one of the other substances listed above.

[0066] According to some embodiments of the present invention, the lithium-philic active layer 2 further includes a first conductive material and a binder. The addition of the first conductive material can form a conductive network in the lithium-philic active layer 2, which is conducive to the rapid transmission of electrons in the negative electrode plate 10, reduces the internal resistance of the battery, and improves the charge and discharge efficiency and rate performance of the battery. The binder can firmly combine the lithium-philic active sites, the first conductive material and the current collector 1 together, prevent the lithium-philic active sites from falling off or agglomerating during the charge and discharge process, help maintain the structural integrity of the negative electrode plate 10, and improve the cycle stability of the lithium battery.

[0067] According to some embodiments of the present invention, the mass ratio of the first conductive material to the lithium-philic active site is (1-99): 1. For example, it can be 1: 1, 5: 1, 10: 1, 20: 1, 40: 1, 70: 1, 99: 1, etc. By limiting the mass ratio of the first conductive material to the lithium-philic active site to the above range, a dense conductive network can be formed in the lithium-philic active layer 2, which is conducive to the rapid transmission of electrons in the negative electrode plate 10, reduces the internal resistance of the battery, and improves the rate performance and charge and discharge efficiency of the lithium battery.

[0068] According to some embodiments of the present invention, the first conductive material includes at least one of conductive graphite, conductive carbon black, acetylene black, ketjen black, carbon fiber, single-walled carbon nanotubes, multi-walled carbon nanotubes, polyethylene dioxythiophene, polystyrene sulfonic acid, lithium polystyrene sulfonate, sodium polystyrene sulfonate, graphene, fullerene, silicon carbide, calcium carbide, boron carbide, vanadium carbide, magnesium carbide, titanium carbide, zirconium carbide, tantalum carbide, tungsten carbide and niobium carbide. The above-mentioned first conductive material can form a conductive network in the lithium-philic active layer 2, promote the rapid transmission of electrons, and increase the conductivity of the negative electrode plate 10; the first conductive carbon material can be used as a carbon source to interact with the lithium-philic active site to form a stable composite material, which can further improve the conductivity of the negative electrode plate 10. For example, graphene has a high specific surface area and good adsorption performance, can adsorb silver element, and promote the formation of Ag-C composite material.

[0069] It should be noted that there is no particular limitation on the type of binder, and those skilled in the art can flexibly select the binder as needed.

[0070] As an example, the binder includes at least one of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium hydroxymethylcellulose, styrene-butadiene rubber, nitrile rubber, styrene-butadiene-styrene copolymer, polyacrylic acid, and lithium polyacrylate.

[0071] According to some embodiments of the present invention, the negative electrode plate 10 further includes a lithium metal layer, and the lithium metal layer is disposed on the side of the lithium-philic active layer 2 away from the current collector 1. The lithium metal layer is disposed on the side of the lithium-philic active layer 2 away from the current collector 1, and the lithium-philic active layer 2 can guide lithium ions to be deposited on the lithium metal layer in an orderly manner, reduce the formation of lithium dendrites, and thus achieve a higher capacity utilization rate. The lithium metal layer has good electrical conductivity and can accelerate the transmission speed of electrons in the negative electrode plate 10. During high-rate charge and discharge, electrons can quickly reach the lithium metal layer, promoting the insertion and extraction reactions of lithium ions.

[0072] It can be understood that when the negative electrode plate contains a lithium metal layer, the resulting battery is a lithium metal battery. Of course, the negative electrode plate may also not have a lithium metal layer, in which case the resulting battery is a negative electrode-free lithium metal battery.

[0073] According to some embodiments of the present invention, the negative electrode plate 10 further includes an intermediate composite layer 3, and the intermediate composite layer 3 is disposed on the side of the lithium-philic active layer 2 away from the current collector 1. The negative electrode plate 10 constructed by the current collector 1, the lithium-philic active site and the intermediate composite layer 3 provides a rich storage space or a three-dimensional network space for the embedding and deposition of lithium, so that lithium metal has enough positions for reversible embedding and extraction during the charging and discharging process, thereby improving the capacity of the battery. The three-dimensional network structure can accommodate more lithium metal, prevent lithium from growing on the interface between the lithium-philic active layer and the intermediate composite layer, prevent the disordered growth of lithium dendrites, promote the uniform distribution of lithium ions, and improve the cycle performance of the battery. In the process of rapid diffusion of ions and electrons, the intermediate composite layer 3 can provide a supporting skeleton for the lithium-philic active site, can effectively inhibit volume expansion, act as a mechanical stress buffer layer, and enhance the structural stability of the negative electrode plate 10, which is beneficial to improving the cycle performance and safety performance of the lithium battery. The metallic lithium-based alloy guided by the lithium-philic active sites can form an electron / ion three-dimensional conductive network in the composite material layer during the directional growth process, which helps to improve the electrochemical performance of the negative electrode plate 10 and promote the rapid transmission of ions and electrons.

[0074] Furthermore, the formation of the intermediate composite layer 3 can also prevent lithium metal from being deposited at the interface between the solid electrolyte layer and the intermediate composite layer, avoiding direct contact with the intermediate solid electrolyte layer 4 in the subsequent preparation process of the lithium battery, thereby further reducing the generation of interface side reactions and dead lithium, which is beneficial to improving the cycle stability of the lithium battery. The negative electrode plate 10 constructed by the current collector 1, the lithium-philic active site and the intermediate composite layer 3 can increase the precipitation and effective contact area of ​​the lithium-rich phase. Among them, the lithium-philic active site can guide the precipitation of the lithium-rich phase, and the three-dimensional network structure of the intermediate composite layer 3 can increase the contact area between the lithium-rich phase and the electrolyte, and improve the ion transfer efficiency. As a result, the cycle performance and safety performance of the lithium battery can be improved.

[0075] It should be noted that the lithium-philic active layer may not completely cover the surface of the current collector, so that the intermediate composite layer can be in contact with the lithium-philic active layer and the current collector at the same time.

[0076] It should be noted that when there is a lithium metal layer in the negative electrode plate, the intermediate composite layer 3 can also be arranged on the side of the lithium metal layer away from the lithium-philic active layer 2, and those skilled in the art can make a flexible choice according to needs.

[0077] According to some embodiments of the present invention, the thickness of the intermediate composite layer 3 is 10 μm-100 μm. For example, it can be 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, etc. By limiting the thickness of the intermediate composite layer 3 to the above range, the volume of lithium metal will change during the charging and discharging process, and the elastic structure of the intermediate composite layer 3 can adapt to the volume change of lithium metal, reduce the expansion and contraction of the negative electrode plate 10, and improve the cycle life of the lithium battery.

[0078] It should be noted that there is no particular limitation on the type of the intermediate composite layer 3 , and those skilled in the art can flexibly select the type according to needs.

[0079] According to some embodiments of the present invention, the intermediate composite layer 3 includes at least one of reticulated glassy carbon, etherified reticulated cellulose, cellulose, lignin, ether lignin, chitosan, alginic acid, lithium alginate, sodium alginate, graphite, graphene, hard carbon, soft carbon, fullerene, elemental silicon, silicon-oxygen material, silicon-carbon material, silicon-nitrogen material, silicon-based alloy, elemental tin, tin-based alloy, lithium metal, lithium-based alloy, lithium-titanium oxide, transition metal oxide, transition metal sulfide, second conductive material, porous carbon material, carbon molecular sieve, mesoporous material, metal organic framework compound, covalent organic framework material, zeolite imidazole ester framework structure material, 6-amino-1-hexanol-polyacrylic acid, hydroxyethylethylenediamine-polyacrylic acid, diglycolamine-polyacrylic acid ion cross-linked polymer, 5-amino-1-pentanol-polyacrylic acid, 4-amino-1-butanol-polyacrylic acid, N,N-bis(2-hydroxyethyl)ethylenediamine-polyacrylic acid and solid electrolyte. The above-mentioned intermediate composite layer 3 can provide abundant storage space or three-dimensional network space for the embedding and deposition of lithium, so that lithium metal has enough position for reversible embedding and extraction during the charging and discharging process, thereby improving the capacity of the battery. The three-dimensional network structure can accommodate more lithium metal, prevent lithium from growing on the interface between the lithium-philic active layer and the intermediate composite layer, prevent the disordered growth of lithium dendrites, promote the uniform distribution of lithium ions, and improve the cycle performance of the battery. In the process of rapid diffusion of ions and electrons, the intermediate composite layer 3 can provide a supporting skeleton for the lithium-philic active sites, effectively inhibit volume expansion, act as a mechanical stress buffer layer, enhance the structural stability of the negative electrode plate 10, and help improve the cycle performance and safety performance of the lithium battery. The metal lithium-based alloy guided by the lithium-philic active sites can form an electron / ion three-dimensional conductive network in the composite material layer during the directional growth process, which helps to improve the electrochemical properties of the negative electrode plate 10 and promote the rapid transmission of ions and electrons. Moreover, the three-dimensional network carbon layer can act as a physical barrier to prevent lithium metal from depositing at the interface between the solid electrolyte layer and the intermediate composite layer, avoiding direct contact with the intermediate solid electrolyte layer 4 in the subsequent preparation process of the lithium battery, thereby further reducing interface side reactions and the generation of dead lithium, which is beneficial to improving the cycle stability of the lithium battery.

[0080] As an example, the transition metal oxide includes a tin oxide compound.

[0081] As an example, the second conductive material includes at least one of conductive graphite, conductive carbon black, acetylene black, Ketjen black, carbon fiber, single-walled carbon nanotubes, multi-walled carbon nanotubes, polyethylene dioxythiophene, polystyrene sulfonic acid, lithium polystyrene sulfonate, sodium polystyrene sulfonate, graphene, fullerene, silicon carbide, calcium carbide, boron carbide, vanadium carbide, magnesium carbide, titanium carbide, zirconium carbide, tantalum carbide, tungsten carbide and niobium carbide.

[0082] As an example, the solid electrolyte includes at least one of an oxide solid electrolyte, a sulfide solid electrolyte, a halide solid electrolyte, a hydride solid electrolyte, a borate solid electrolyte, a nitride solid electrolyte and a polymer solid electrolyte.

[0083] As an example, the oxide solid electrolyte includes at least one of a garnet-type solid electrolyte, a perovskite-type solid electrolyte, a NASICON-type solid electrolyte, and a LISICON-type solid electrolyte.

[0084] It should be noted that NASICON-type active fillers refer to active materials with a sodium superionic conductor (Na Super Ionic Conductor, NASICON) structure, which is a three-dimensional open framework structure composed of metal ions and polyhedrons; LISICON-type active fillers refer to a class of materials with a lithium superionic conductor (Lithium Super Ionic Conductor, LISICON) structure.

[0085] As an example, the garnet-type solid electrolyte includes Li x1 La 3 Zr y1 A1 z1 O 12 and Li x2 La 3-y2 B1 y2 Zr z2 O 12 At least one of the following, wherein Li x1 La 3 Zr y1 A1 z1 O 12 Satisfies: 6≤x1≤7, 1≤y1≤2, 0≤z1≤0.5, A1 includes at least one of Ta, Nb, Mg, Ti, Te, W; Li x2 La 3-y2 B1 y2 Zr z2 O 12 Satisfies: 6≤x2≤7, 0≤y2≤0.5, 1≤z2≤2, and B2 includes at least one of Ca, Rb, Al, and Ga.

[0086] As an example, the perovskite solid electrolyte includes Li 3.3 La 0.53 TiO 3 Li 3x3 La 2 / 3-x3 TiO 3 and Li x4 Sr y3 M1 z3TaO 3 At least one of the following, wherein Li 3.3 La 0.53 TiO 3 Li 3x3 La 2 / 3-x3 TiO 3 Satisfies: 0≤x3≤2 / 3; M1 includes at least one of Zr and Nb.

[0087] As an example, the NASICON-type solid electrolyte includes Li x5 Al y4 M2 z4 (PO 4 ) 3 , Li x6 Y y5 Zr z5 (PO 4 ) 3 、LiTi 2 (PO 4 ) 3 ,LiGe 2 (PO 4 ) 3 and LiGeTi(PO 4 ) 3 At least one of the following, wherein Li x5 Al y4 M2 z4 (PO 4 ) 3 Satisfying: 1.3≤x5≤1.5, 0.3≤y4≤0.5, 1.5≤z4≤1.7, M2 includes at least one of Ti, Ge, Hf, Zn, Zr and Si; Li x6 Y y5 Zr z5 (PO 4 ) 3 Satisfies: 1.3≤x6≤1.5, 0.3≤y5≤0.5, 1.5≤z5≤1.7.

[0088] As an example, the LISICON type solid electrolyte includes Li 3+x7 (P 1x7 Si x7 ) 4 and Li 3+x8 Ge x8 V 1x8 O 4 At least one of the following, wherein Li 3+x7 (P 1x7 Si x7 ) 4 Satisfies: 0≤x7≤0.5; Li 3+x8Ge x8 V 1x8 O 4 Satisfies: 0.25≤x8≤0.72.

[0089] As an example, the sulfide solid electrolyte includes Argyrodite-type LiPSM3X1, Thio-LiSICON-type Li 4-x9 A2 1-x9 B2 x9 S 4 and at least one of glassy sulfides, wherein LiPSM3X1 satisfies: M3 includes at least one of O, Cu, Zn, Bi, Sn, Al, Mn, Ce and In, and X1 includes at least one of F, Cl, Br and I; Li 4-x9 A 1-x9 B x9 S 4 Satisfying: 0≤x9≤0.5, A2 includes at least one of Si, Sn, Ge and Zr, and B2 includes at least one of O, P, Al, Zn and Ga.

[0090] As an example, the glassy sulfide includes Li 2 SP 2 S 5 , Li 2 S-GeS 2 , Li 2 S-SiS 2 , Li 2 S-SiS 2 -Li 4 SiO 4 , Li 2 SB 2 S 3 and Li 2 SB 2 S 3 -At least one of LiI.

[0091] As an example, the halide solid electrolyte includes LiX2, Li 2 M4X3 4 , Li 3 M5X4 6 , Li x M6 y Ln z Cl 3 、LiM7Cl 5 X5 and Li 3-y7 Zr y7 M8 1-y7 Cl 6At least one of them, LiX2 satisfies: X2 includes at least one of F, Cl, Br, and I; Li 2 M4X3 4 satisfies: M4 includes at least one of Mg, Mn, Fe, Zn, and Cd, and X3 includes at least one of F, Cl, Br, and I; Li 3 M5X4 6 satisfies: M5 includes at least one of O, In, Y, Yb, Sc, Ho, and Er, and X4 includes at least one of F, Cl, Br, and I; Li x10 M6 y6 Ln z6 Cl 3 satisfies: 0 ≤ x10 ≤ 0.5, 0 ≤ y6 ≤ 0.83, 0 ≤ z6 ≤ 0.83, M6 includes at least one of Ta, Zr, Ca, and Al, and Ln includes at least one of La, Ce, Pr, Nd, and Sm; LiM7Cl 5 X5 satisfies: M7 includes at least one of La, Ta, and Nb, and X5 includes at least one of O, Cl, F, and OH; Li 3-y7 Zr y7 M8 1-y7 Cl 6 satisfies: 0 < y7 < 1, and M8 includes at least one of Y, Er, Yb, Ho, and Lu.

[0092] As an example, the hydride solid electrolyte includes Li 3 AlH 6 , LiBH 4 , LiNH 2 , Li 2 NH, LiBH 4 -LiNH 2 , LiBH 4 -LiX6, where LiBH 4 -LiX6 satisfies: X includes at least one of Cl, Br, and I.

[0093] As an example, the borate solid electrolyte can be selected from Li 2 B 4 O 7 and Li 2 O-B 2 O 3 -P 2 O 5 at least one of them.

[0094] As an example, the nitride solid electrolyte can be selected from LiPON, Li 3 N, Li 7 PN 4and LiSi 2 N 3 At least one of .

[0095] As an example, the polymer solid electrolyte includes a lithium salt and a polymer.

[0096] As an example, the polymer includes, but is not limited to, one or more of polyethylene oxide, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-chlorotrifluoroethylene, polyacrylonitrile, polymethyl methacrylate, polypropylene carbonate, polyphenylene sulfide, polyethyl cyanoacrylate, polypentylene succinate, polyvinyl chloride, polyvinylene carbonate, chitosan, polyimide, polyacrylate, polyurethane, aramid, polyetherimide, polyamide, polysulfone, aromatic sulfone, polyaromatic sulfone, polyethersulfone, epoxy resin and polyphenylene sulfone resin.

[0097] As an example, the lithium salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, and lithium difluorooxalatoborate.

[0098] According to some embodiments of the present invention, the negative electrode plate 10 further includes a solid electrolyte layer 4, and the solid electrolyte layer 4 is disposed on a side of the intermediate composite layer 3 away from the lithium-philic active layer 2. The solid electrolyte layer 4 can provide a specific ion transmission channel, promote the rapid migration of lithium ions between the negative electrode plate 10 and other parts of the battery, help improve the battery's charge and discharge efficiency and rate performance, enable the lithium battery to charge and discharge quickly, and combine with the active site to achieve uniform lithium deposition. The solid electrolyte layer 4 is located between the intermediate composite layer 3 and the lithium-philic active layer 2 and the external environment, plays a role of isolation and protection, generates a stable SEI layer, can prevent external impurities, moisture or other impurities from entering the negative electrode plate 10, and can also reduce the negative electrode plate 10 and the side reactions in the system, which is beneficial to improve the cycle stability and safety performance of the lithium battery.

[0099] It should be noted that there is no special limitation on the solid electrolyte in the solid electrolyte layer 4. The selection of solid electrolytes has been listed and explained above, and will not be described in detail here. Those skilled in the art can flexibly select according to needs.

[0100] In a second aspect, the present invention provides a method for preparing the negative electrode plate 10 of the first aspect. According to an embodiment of the present application, the method comprises: preparing the lithium-philic active layer 2 on at least one side of the current collector 1, the lithium-philic active layer 2 comprising lithium-philic active sites, and functional groups are grafted onto the lithium-philic active sites, and the functional groups comprise at least one of silicon-containing functional groups, nitrogen-containing functional groups, sulfur-containing functional groups and boron-containing functional groups.

[0101] According to the method of the embodiment of the present application, the current collector 1 serves as a basic support, and a lithium-philic active layer 2 is formed on at least one side of the current collector 1. Through the action of chemical bonds, at least one of the silicon-containing functional groups, nitrogen-containing functional groups, sulfur-containing functional groups and boron-containing functional groups can be stably grafted on the lithium-philic active sites. The grafting of functional groups can effectively prevent the agglomeration of the lithium-philic active sites, ensuring that the lithium-philic active sites can be evenly distributed on the current collector 1 in a dispersed state; the grafting of functional groups can also firmly anchor the lithium-philic active sites on the surface of the current collector 1, preventing the lithium-philic active sites from falling off or moving during the battery cycle, which is beneficial to maintaining the cycle stability of the battery; the lithium-philic active sites grafted with functional groups can form lithium metal nucleation sites, inducing lithium ions to be directional deposited along the (110) crystal plane. , thereby inhibiting the disordered growth of lithium dendrites, which is beneficial to improving the safety performance and cycle stability of lithium batteries; when the functional group is grafted on the lithium-philic active site, the electronic structure and chemical properties of the surface of the current collector 1 can be adjusted to change the interaction between the surface of the current collector 1 and lithium metal, which helps to promote the lattice matching of the low potential energy crystal planes between the surface of the current collector 1 and lithium metal, making the deposition of lithium on the surface of the current collector 1 more orderly and evenly distributed on the current collector 1. Uniform lithium deposition can improve the cycle stability and safety of lithium batteries; and when the lattice matching between the surface of the current collector 1 and lithium metal is improved, the nucleation and growth of lithium ions on the surface of the current collector 1 become easier, reducing the potential energy of lithium nucleation and growth, which is beneficial to improving the safety performance of lithium batteries. Therefore, the negative electrode sheet 10 provided by the present application can improve the rate performance, cycle stability and safety performance of lithium batteries.

[0102] According to some embodiments of the present invention, the step of preparing the lithium-philic active layer 2 on at least one side of the current collector 1 includes:

[0103] The lithium-philic active site precursor, the functional group precursor, the reducing agent, the conductive material, the binder, the dispersant and the solvent are mixed and subjected to a reduction reaction to obtain a first precursor solution;

[0104] The first precursor solution is introduced into at least one side of the current collector 1 to form the lithium-philic active layer 2 .

[0105] By mixing the lithium-philic active site precursor, the functional group precursor, the reducing agent, the conductive material, the binder, the dispersant and the solvent, it is possible to ensure that the various components are fully mixed in the solvent, so that a uniform distribution is achieved when the lithium-philic active layer 2 is formed, which can ensure the uniform transmission and storage of lithium ions in the negative electrode sheet 10, and reduce local polarization and capacity decay. At the same time, the uniform distribution of the conductive material and the binder can improve the conductivity and mechanical strength of the negative electrode sheet 10, and the conductive material can provide an electron transmission channel, promote charge transfer, and improve the charge and discharge efficiency of the battery. The binder can firmly combine the lithium-philic active site, the conductive material and the current collector 1 together to prevent the negative electrode sheet 10 from falling off and being damaged during the charge and discharge process, which is beneficial to improving the cycle stability of the battery. The reducing agent can promote the reduction of the lithium-philic active site precursor, converting it into a lithium-philic active site with lithium-philicity, and the functional group precursor can provide a specific functional group to be grafted on the lithium-philic active site, which can effectively prevent the agglomeration of the lithium-philic active site, and the obtained first precursor solution can be conveniently introduced into at least one side of the current collector 1, and the fluidity of the first precursor solution allows it to be evenly spread on the surface of the current collector 1 to form a uniform lithium-philic active layer 2. Thus, the safety performance and cycle stability of the lithium battery can be improved.

[0106] According to some embodiments of the present invention, based on the total mass of the first precursor solution, the mass proportion of the binder is 1%-10%. For example, it can be 1%, 2%, 4%, 8%, 10%, etc. By limiting the mass proportion of the binder to the above range, it is possible to play a moderate bonding role in the lithium-philic active layer 2, and the lithium-philic active sites, conductive materials, etc. can be firmly combined with the current collector 1 to prevent falling off and damage during the battery charging and discharging process, which is beneficial to improving the cycle stability of the lithium battery.

[0107] According to some embodiments of the present invention, the lithium-philic active site precursor includes at least one of a soluble magnesium source, a soluble zinc source, a soluble nickel source, a soluble aluminum source, a soluble silver source, a soluble gold source, a soluble molybdenum source, a soluble lead source, a soluble tin source, a soluble bismuth source, a soluble palladium source, a soluble ruthenium source, a soluble iridium source, a soluble platinum source, a soluble cerium source, a soluble indium source, a soluble silicon source, and a soluble carbon source. The metal element after reduction of the lithium-philic active site precursor can react with lithium to form an alloy or have a specific chemical adsorption effect, showing good lithium affinity.

[0108] As an example, the soluble silver source includes at least one of silver nitrate, silver sulfate, silver fluoride, silver perchlorate, and silver acetate.

[0109] As an example, the reducing agent includes at least one of zinc powder, glucose, hydrazine hydrate, dodecyltetraethylene glycol ether, dimethylamine-borane, polyamide, lithium citrate and sodium citrate.

[0110] As an example, the dispersant includes at least one of polyvinyl pyrrolidone, aniline, sodium naphthalene formaldehyde sulfonate, dihexadecyl pyridinium dithiophosphate, polyacrylic acid, cysteine ​​and polyvinyl epoxy nonphenyl ether.

[0111] According to some embodiments of the present invention, the introduction method includes at least one of concave roller, coating, spraying and chemical vapor deposition (CVD). The use of concave roller, coating, spraying, chemical vapor deposition and other process methods to introduce functional group-grafted lithium-philic active sites on the surface of the current collector 1 can achieve a uniform distribution of lithium-philic active sites, ensure uniform transmission and storage of lithium ions in the negative electrode sheet 10, reduce local polarization and capacity attenuation, and help improve the charge and discharge efficiency, rate performance and cycle stability of the battery.

[0112] As an example, the solvent includes, but is not limited to, one or more of methylpyrrolidone, dimethylformamide, dimethylacetamide, butyrate, toluene, xylene, anisole, hexane, heptane, dibromomethane, dichloroethane, ethanol, and glycol ether.

[0113] According to some embodiments of the present invention, the step of preparing the lithium-philic active layer 2 on at least one side of the current collector 1 includes:

[0114] The lithium-philic active site precursor, the functional group precursor, the reducing agent, the conductive material, the binder and the solvent are mixed to perform a first reduction reaction to obtain a second precursor solution;

[0115] The second precursor solution is introduced into at least one side of the current collector 1 to perform a second reduction reaction to form the lithium-philic active layer 2 .

[0116] The efficiency and controllability of the reaction can be improved by performing two reduction reactions. The first reduction reaction can cause a preliminary reaction between multiple components such as lithium-philic active site precursors and functional group precursors to form intermediate products with certain activity. The second reduction reaction can further convert these intermediate products into a stable lithium-philic active layer 2. This staged reduction reaction can better control the progress of the reaction and the properties of the products, improve the quality and performance of the lithium-philic active layer 2, significantly enhance the lithium-philicity of the negative electrode plate 10, promote the adsorption and uniform nucleation growth of lithium ions, help to improve the capacity and energy density of the battery, and also improve the charge and discharge efficiency and rate performance of the battery.

[0117] According to some embodiments of the present invention, the temperature of the first reduction reaction is 80°C-300°C. For example, it can be 80°C, 100°C, 150°C, 200°C, 250°C, 300°C, etc. The time of the first reduction reaction is 3h-10h. For example, it can be 3h, 5h, 7h, 9h, 10h, etc. Controlling the temperature and time of the first reaction can improve the conversion rate of some reduction products, improve the stability of active sites during the cycle, remove excess solvation structures in the system, and reduce the generation of side reactions; secondly, controlling the reaction temperature and time can reduce the size, nucleation density and crystallinity of the lithium-philic active sites, which is conducive to the formation of lithium-philic active sites with consistent size and uniform distribution.

[0118] According to some embodiments of the present invention, based on the total mass of the second precursor solution, the mass proportion of the binder is 1%-10%. For example, it can be 1%, 2%, 4%, 8%, 10%, etc. By limiting the mass proportion of the binder to the above range, a moderate bonding effect can be exerted in the lithium-philic active layer 2, and the lithium-philic active sites, conductive materials, etc. can be firmly combined with the current collector 1 to prevent falling off or failure during the battery charging and discharging process, which is beneficial to improving the cycle stability of the lithium battery.

[0119] According to some embodiments of the present invention, the second reduction reaction comprises at least one of liquid phase reduction and ultraviolet reduction. By adopting the above reduction method, a lithium-philic active layer 2 with high lithium-philic activity, good conductivity and uniformity can be formed on the surface of the current collector 1, thereby improving the electrochemical performance and cycle stability of the battery.

[0120] It should be noted that liquid phase reduction refers to the process of heating the second precursor solution after it is introduced into at least one side of the current collector 1, so that the solvent evaporates on the one hand and the lithium-philic active site precursor in the second precursor solution continues to undergo a reduction reaction on the other hand, and finally forms a lithium-philic active layer 2 on the current collector 1. Ultraviolet reduction refers to the process of irradiating and heating the second precursor solution with an ultraviolet lamp after it is introduced into at least one side of the current collector 1, so that the lithium-philic active site precursor in the second precursor solution continues to undergo a reduction reaction, and finally forms a lithium-philic active layer 2 on the current collector 1.

[0121] According to a specific embodiment of the present invention, the method further includes:

[0122] The lithium metal layer is prepared on the side of the lithium-philic active layer 2 away from the current collector 1 .

[0123] Preparing a lithium metal layer on the side of the lithium-philic active layer 2 away from the current collector 1 can significantly increase the overall capacity of the battery. When the battery is charged and discharged, the lithium metal layer can provide a large amount of lithium ions to participate in the reaction, thereby improving the energy storage capacity of the battery.

[0124] According to some embodiments of the present invention, the method for preparing the lithium metal layer includes at least one of electrochemical deposition, evaporation and continuous rolling. The lithium metal layer is prepared on the side of the lithium-philic active layer 2 away from the current collector 1 by electrochemical deposition or evaporation, and the lithium metal is induced to be directional deposited along the low potential energy (110) crystal plane on the lithium-philic active site grafted with the functional group, so that vertical structure lithium conduction can be achieved, which is conducive to the rapid transmission of lithium ions, prevents the disordered nucleation and growth of lithium dendrites, and improves the charge and discharge efficiency and rate performance of the battery. The (110) crystal plane has a lower surface energy and better lithium ion diffusion performance, which can promote the uniform distribution and stable storage of lithium ions in the negative electrode sheet 10. By directional deposition on this crystal plane, its advantages can be fully utilized to improve the lithium conduction performance of the negative electrode sheet 10. At the same time, the vertical structure can also increase the contact area between the negative electrode sheet 10 and the electrolyte, further improving the ion transmission efficiency. Alternatively, lithium metal is repeatedly rolled on the lithium-philic active layer 2 through a continuous rolling directional bonding process, so that the lithium metal is directional bonded with the lithium-philic active sites on the lithium-philic active layer 2, thereby forming a lithium-based alloy with a (110) orientation. The (110)-oriented lithium-based alloy can guide lithium ions to deposit uniformly on the surface of the negative electrode plate 10, grow directional along the low potential energy surface, inhibit the disordered growth of lithium dendrites in the nucleation growth stage, and help improve the safety performance and cycle stability of the lithium battery.

[0125] According to some embodiments of the present invention, the temperature of the electrochemical deposition is -15°C-60°C. For example, it can be -15°C, -10°C, -5°C, 0°C, 5°C, 10°C, 20°C, 40°C, 60°C, etc. By limiting the temperature of the electrochemical deposition within the above range, lithium ions can diffuse at a more appropriate speed, which is conducive to the uniform deposition of lithium metal on the surface of the lithium-philic active layer 2, and helps to control the reduction reaction rate and surface diffusion changes during the preparation of the lithium-philic layer by electrodeposition, so as to achieve uniform deposition and reduce the generation of defects. Further, the temperature of the electrochemical deposition is preferably 2°C-20°C.

[0126] According to some embodiments of the present invention, the method further comprises:

[0127] The intermediate composite layer 3 is prepared on the side of the lithium-philic active layer 2 away from the current collector 1 .

[0128] By preparing the intermediate composite layer 3 on the side of the lithium-philic active layer 2 away from the current collector 1, the negative electrode plate 10 constructed by the current collector 1, the lithium-philic active site and the intermediate composite layer 3 provides a rich storage space or a three-dimensional network space for the embedding and deposition of lithium, so that lithium metal has enough positions for reversible embedding and extraction during the charging and discharging process, thereby improving the capacity of the battery. The three-dimensional network structure can accommodate more lithium metal, prevent the disordered growth of lithium dendrites, promote the uniform distribution of lithium ions, and improve the cycle performance of the battery. In the process of rapid diffusion of ions and electrons, the intermediate composite layer 3 can provide a supporting skeleton for the lithium-philic active site, effectively inhibit volume expansion, act as a mechanical stress buffer layer, and enhance the structural stability of the negative electrode plate 10, which is beneficial to improving the cycle performance and safety performance of the lithium battery. The metallic lithium guided by the lithium-philic active site can form an electron / ion three-dimensional conductive network in the composite material layer during the directional growth process, which helps to improve the electrochemical performance of the negative electrode plate 10 and promote the rapid transmission of ions and electrons.

[0129] Furthermore, the formation of the intermediate composite layer 3 can also prevent lithium metal from being deposited at the interface between the intermediate composite layer and the solid electrolyte layer, avoiding direct contact with the intermediate solid electrolyte layer 4 in the subsequent preparation process of the lithium battery, thereby further reducing the generation of interface side reactions and dead lithium, which is beneficial to improving the cycle stability of the lithium battery. The negative electrode plate 10 constructed by the current collector 1, the lithium-philic active site and the intermediate composite layer 3 can increase the precipitation and effective contact area of ​​the lithium-rich phase. Among them, the lithium-philic active site can guide the precipitation of the lithium-rich phase, and the three-dimensional network structure of the intermediate composite layer 3 can increase the contact area between the lithium-rich phase and the electrolyte, and improve the ion transfer efficiency. As a result, the cycle performance and safety performance of the lithium battery can be improved.

[0130] It should be noted that the intermediate composite layer 3 may also be prepared on the side of the lithium metal layer away from the lithium-philic active layer 2 , and those skilled in the art may flexibly select the layer according to their needs.

[0131] As an example, the preparation method of the intermediate composite layer 3 includes but is not limited to at least one of coating and spraying.

[0132] According to some embodiments of the present invention, the method further comprises: preparing a solid electrolyte layer 4 on a side of the intermediate composite layer 3 away from the lithium-philic active layer 2 .

[0133] The solid electrolyte layer 4 can provide a specific ion transmission channel, promote the rapid migration of lithium ions between the negative electrode plate 10 and other parts of the battery, and help improve the charge and discharge efficiency and rate performance of the battery, so that the battery can complete charging or release more energy in a shorter time. The solid electrolyte layer 4 is located between the intermediate composite layer 3 and the lithium-philic active layer 2 and the external environment, and plays an isolation and protection role, which can prevent external impurities, moisture or other harmful substances from entering the negative electrode plate 10, and can also reduce the side reactions between the negative electrode plate 10 and the external environment, which is conducive to improving the cycle stability and safety performance of the battery.

[0134] According to the preparation method of an embodiment of the present invention, at least one of the silicon-containing functional group, the nitrogen-containing functional group, the sulfur-containing functional group and the boron-containing functional group can be stably grafted on the lithium-philic active site through the action of chemical bonds, which can prevent the agglomeration of the lithium-philic active site and ensure that the lithium-philic active site exists in a dispersed state on the surface of the current collector 1. On the other hand, the grafting of the functional group can also firmly anchor the lithium-philic active site on the surface of the current collector 1, which can improve the stability of the lithium-philic active site, avoid the shedding of the lithium-philic active site during the use of the battery, and ensure the cycle stability of the battery performance. The grafted lithium-philic active site can induce the directional deposition of lithium ions, so that the lithium ions are deposited in an orderly manner on the surface of the negative electrode plate 10, rather than growing disorderly, thereby effectively preventing the formation of lithium dendrites, which is beneficial to improving the safety and cycle stability of the battery. The grafted lithium-philic active site can also achieve a uniform distribution of the lithium-philic active site, ensuring the uniform transmission and storage of lithium ions in the negative electrode plate 10, and reducing local polarization and capacity attenuation.

[0135] Furthermore, the lithium-philic active sites grafted with functional groups are introduced on the surface of the current collector 1 by using processes such as concave roller, coating, spraying, and chemical vapor deposition, which can achieve uniform distribution of the lithium-philic active sites on the surface of the current collector 1 and improve the performance of the negative electrode sheet 10. The metal active sites are then reduced by methods such as liquid phase reduction and ultraviolet light reduction, which can achieve the reduction of the active sites under relatively mild conditions, avoid damage to the active sites and the current collector 1 by harsh conditions such as high temperature and high pressure, and prevent agglomeration. At the same time, these reduction methods can accurately control the reduction process and improve the activity and performance of the active sites.

[0136] Furthermore, by constructing the lattice matching degree of the (110) crystal plane between the current collector 1 and lithium through the lithium-philic active sites, the uniform deposition of lithium on the surface of the current collector 1 can be promoted. The improvement of the lattice matching degree can reduce the potential energy of lithium nucleation and growth, making it easier for lithium ions to nucleate and grow on the surface of the current collector 1, thereby achieving more uniform lithium deposition, helping to reduce the risk of lithium dendrite formation and improve the safety performance of the battery.

[0137] Furthermore, lithium metal is introduced onto the lithium-philic active layer 2 by electrochemical deposition or evaporation, and lithium metal is induced to be directional deposited along the low potential energy (110) crystal plane at the grafted lithium-philic active sites, so that vertical structure lithium conduction can be achieved, which is beneficial to the rapid transmission of lithium ions and improves the charge and discharge efficiency and rate performance of the battery. At the same time, the vertical structure can also increase the contact area between the negative electrode plate 10 and the electrolyte, further improving the ion transmission efficiency. By repeatedly rolling lithium metal on the surface of the lithium-philic active layer 2 through a continuous rolling directional bonding process, a (110) oriented lithium-based alloy is prepared, which can induce uniform deposition of lithium ions, effectively prevent the disordered growth of lithium dendrites, and improve the safety and cycle stability of the battery. At the same time, the (110) oriented lithium-based alloy can provide a more stable lithium ion storage environment, further inhibiting the growth of lithium dendrites.

[0138] Furthermore, an intermediate composite layer 3 is introduced on the lithium-philic active layer 2, and a three-dimensional network carbon layer is preferably composited with the lithium-philic active site, which can prevent lithium metal from being deposited at the interface between the intermediate composite layer and the solid electrolyte layer, avoiding direct contact with the solid electrolyte, helping to reduce the occurrence of side reactions and improve the performance and safety of the battery. At the same time, the intermediate composite layer 3 can also act as a mechanical stress buffer layer, effectively inhibiting volume expansion and alleviating internal stress changes during lithium deposition. The intermediate composite layer 3 can prevent lithium dendrites from piercing the solid electrolyte layer 4 between the lithium-philic active layer 2 and the subsequent solid electrolyte layer 4, protecting the internal structure of the battery. At the same time, constructing a three-dimensional network structure can reduce the occurrence of side reactions, prevent lithium from nucleating and growing in the solid electrolyte, and help improve the cycle stability and safety performance of the battery.

[0139] Furthermore, the lithium-philic active sites can provide storage and transmission sites for lithium ions, while the intermediate composite layer 3 can provide transmission channels for electrons. The synergistic effect of the lithium-philic active sites and the intermediate composite layer 3 can promote the transmission of lithium ions and electrons. The synergistic effect of the lithium-philic active sites and the intermediate composite layer 3 can also improve the interface stability, wherein the lithium-philic active sites can interact with lithium ions to regulate the transmission and storage behavior of lithium ions, while the intermediate composite layer 3 can isolate the negative electrode plate 10 from the electrolyte and reduce the occurrence of side reactions. Thus, the electrochemical performance and cycle stability of the lithium battery can be effectively improved.

[0140] In the third aspect of the present invention, the present invention provides a lithium battery. According to an embodiment of the present invention, the lithium battery comprises the negative electrode sheet 10 of the first aspect or the negative electrode sheet 10 prepared by the method of the second aspect. The battery has excellent safety performance, cycle performance and rate performance.

[0141] It should be noted that the lithium battery also includes a positive electrode plate, which includes a current collector and a positive active material layer, which is arranged on at least one side of the current collector. The positive active material layer includes but is not limited to a positive active material, a conductive agent and a binder. The positive active material includes but is not limited to lithium cobalt oxide, lithium nickel oxide, nickel cobalt manganese ternary material, nickel cobalt aluminum ternary material, lithium-rich manganese base, lithium manganese oxide, lithium nickel manganese oxide, ferroferric oxide and lithium vanadate, lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium nickel phosphate, lithium iron silicate, lithium ferrous sulfate, lithium iron borate and lithium iron titanate. The conductive agent includes but is not limited to at least one of carbon black and graphite, and the binder includes but is not limited to polyvinylidene fluoride (PVDF) and the like.

[0142] The scheme of the present disclosure will be explained below in conjunction with the examples. Those skilled in the art will appreciate that the following examples are only used to illustrate the present disclosure and should not be considered to limit the scope of the present disclosure. Where specific techniques or conditions are not indicated in the examples, the techniques or conditions described in the literature in this area or the product instructions are used. Where the manufacturers of reagents or instruments are not indicated, they are all conventional products that can be obtained commercially.

[0143] Example 1

[0144] 1. Preparation of negative electrode sheet:

[0145] 1) mixing a lithium-philic active site precursor, a functional group precursor, a reducing agent, a first conductive material, a binder, a dispersant and a solvent, maintaining the mixture at a temperature of 150° C. for 6 hours, and performing a first reaction to obtain a second precursor solution, wherein the lithium-philic active site precursor is silver nitrate, the functional group precursor is dopamine, the dispersant is polyvinyl pyrrolidone, the reducing agent is lithium citrate, the first conductive material is conductive graphite, the binder is carboxymethyl cellulose, the solvent is deionized water, and the mass proportion of the binder is 5%;

[0146] 2) introducing the second precursor solution obtained in step 1) into at least one side of the copper foil current collector by coating, irradiating the surface coated with the second precursor solution with ultraviolet light, performing a second reduction reaction, and forming a lithium-philic active layer with a thickness of 30 μm on at least one side of the current collector, wherein the lithium-philic active site is silver, the lithium-philic active site is grafted with a nitrogen-containing functional group, the mass of the nitrogen-containing functional group accounts for 10% of the mass of the lithium-philic active site, the Dv50 particle size of the lithium-philic active site is 100 nm, and the mass ratio of the first conductive material to the lithium-philic active site is 50:1;

[0147] 3) depositing lithium metal on the lithium-philic active layer by electrochemical deposition to form a lithium metal layer on the side of the lithium-philic active layer away from the current collector, wherein the temperature of the electrochemical deposition is 10° C.;

[0148] 4) introducing an intermediate composite layer on the lithium metal layer by coating, forming an intermediate composite layer with a thickness of 50 μm on the side of the lithium metal layer away from the lithium-philic active layer, wherein the material of the intermediate composite layer is meshed glassy carbon;

[0149] 5) preparing a solid electrolyte layer on the side of the intermediate composite layer away from the lithium metal layer to obtain a negative electrode plate: applying a solid electrolyte solution on the side of the intermediate composite layer of the negative electrode plate away from the lithium metal layer and drying it to form a solid electrolyte layer, thereby obtaining a negative electrode plate assembly including a stacked negative electrode plate and a solid electrolyte layer, wherein the thickness of the solid electrolyte layer is 10 μm.

[0150] 2. Prepare the positive electrode sheet: dissolve the positive electrode active material NCM811, the conductive agent conductive carbon black, and the binder polyvinylidene fluoride in N-methylpyrrolidone, with the mass ratio of positive electrode active material: conductive agent: binder being 96:2:2, and then apply it on the surface of the current collector, dry it, and roll it to obtain the positive electrode sheet.

[0151] 3. Prepare lithium battery: Assemble the negative electrode sheet and the positive electrode sheet obtained above into a battery, and hot press them into one to obtain a diaphragm-free lithium battery.

[0152] The negative electrode sheets of Examples 2-15 are the same as those of Example 1 except for different experimental parameters (see Table 1).

[0153] Some experimental parameters of the negative electrode sheets of Examples 1-15 are shown in Table 1.

[0154] Table 1

[0155]

[0156] Comparative Example 1

[0157] The difference between Comparative Example 1 and Example 1 is that: the electrode obtained in Comparative Example 1 does not have a lithium-philic active layer, and the rest is consistent with Example 1.

[0158] Comparative Example 2

[0159] The difference between Comparative Example 2 and Example 1 is that:

[0160] 1) A lithium-philic active site precursor, a reducing agent, a first conductive material, a binder, a dispersant and a solvent are mixed and subjected to a reduction reaction to obtain a second precursor solution.

[0161] Testing and analysis

[0162] Under the same conditions, the lithium batteries prepared in the above Examples 1-15 and Comparative Examples 1-2 were subjected to rate performance, cycle performance and safety performance tests. The specific test methods are as follows:

[0163] First coulombic efficiency test: Use button cells at 25°C, charge and discharge at 0.1C rate, record the first charge and discharge capacity, and calculate the first coulombic efficiency.

[0164] Cycling performance test: In a glove box containing argon, the positive and negative battery shells, stainless steel gaskets, spring sheets, positive electrode sheets, and negative electrode sheets are assembled into button batteries. After the button battery is assembled, it is left to stand at 25°C for 6 hours, and then a constant current charge and discharge mode test is performed using a CT2001A charge and discharge instrument - the battery is first charged, and the battery charge cutoff voltage is 4.2V, and then discharged, and the discharge cutoff voltage is 2.75V, and the test temperature is 25°C. The battery charge and discharge test first performs 2 cycles of cycle activation at a rate of 0.1C, and then performs a long cycle at a rate of 0.5C. Record the first charge and discharge capacity, calculate the first coulomb efficiency, and record the capacity retention rate after the battery is cycled 500 times.

[0165] Safety performance test: Assemble the positive electrode, solid electrolyte, and negative electrode into a 10Ah soft-pack battery, soak at 45°C for 12 hours after injection, and perform a needle puncture test after hot pressing. Before the test, the battery is charged to a cut-off voltage of 4.2V at a constant current and constant voltage rate of 0.33C and left to stand for 1 hour. The test is carried out in an explosion-proof box. The needle parameters are 3mm steel needles, the needle tip cone angle is 45 (the needle surface is smooth, free of rust, oxide layer and oil), and the needle puncture speed is 0.1mm / s. The battery cell is penetrated until it is penetrated. After penetration, let it stand for 1 hour. If the battery does not catch fire or explode, it passes, otherwise it fails.

[0166] The test results are shown in Table 2.

[0167] Table 2

[0168] First coulombic efficiency / % 500 cycles capacity retention rate / % Acupuncture test Example 1 88.13％ 93.6 pass Example 2 88.07％ 82.8 pass Example 3 87.58％ 92.4 pass Example 4 77.65％ 72.1 pass Example 5 78.32％ 76.3 pass Example 6 86.94％ 93.5 pass Example 7 86.59％ 92.7 pass Example 8 86.13％ 92.3 pass Example 9 86.72％ 91.8 pass Example 10 85.86％ 91.5 pass Embodiment 11 85.98％ 92.3 pass Example 12 85.41％ 91.3 pass Embodiment 13 75.90％ 62.7 Not passed Embodiment 14 83.12％ 85.9 pass Embodiment 15 81.76％ 84.3 pass Comparative Example 1 72.64％ / Not passed Comparative Example 2 74.39％ / Not passed

[0169] “ / ” means none.

[0170] Combining Table 1 and Table 2, it can be obtained that compared with the lithium batteries of Comparative Examples 1-2, the first coulombic efficiency and 500-cycle capacity retention rate of the lithium batteries of Examples 1-15 are significantly improved, and the lithium batteries of Examples 1-12 and Examples 14-15 can successfully pass the puncture test, effectively improving the safety performance of the batteries. Among them, the temperature of the first reduction reaction of the negative electrode plate in the lithium battery of Example 13 is too high during the preparation process, which will cause the active components to fail and reduce thermal stability. During the puncture process, the short circuit in the system is aggravated, which will further affect the safety performance of the battery. It cannot pass the puncture test, which will further affect the safety performance of the battery.

[0171] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", "some implementation schemes" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0172] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A negative electrode plate, characterized in that: include: current collector; A lithium-philic active layer is disposed on at least one side of the current collector, wherein the lithium-philic active layer comprises a lithium-philic active site, and a functional group is grafted onto the lithium-philic active site, wherein the functional group comprises at least one of a silicon-containing functional group, a nitrogen-containing functional group, a sulfur-containing functional group and a boron-containing functional group.

2. The negative electrode sheet according to claim 1, characterized in that: The thickness of the lithium-philic active layer is 0.2 nm-60 μm, preferably 0.2 nm-50 μm; Preferably, the mass of the functional group accounts for 1%-20% of the mass of the lithium-philic active site, and the mass of the functional group is calculated based on the mass of the substance providing the functional group; Preferably, the substance providing the functional group includes at least one of amine compounds, silicon fluoride, nitrogen-containing heterocyclic compounds, nitrile compounds, nitro compounds, thienyl-containing compounds, and furanyl thiocarboxylates; Preferably, the amine compound includes at least one of dopamine, aromatic amine, sulfonylated amine, and halogenated aromatic amine; Preferably, the nitrogen-containing heterocyclic compound comprises thiourea.

3. The negative electrode sheet according to claim 1 or 2, characterized in that: The Dv50 particle size of the lithium-philic active site is 0.1nm-500nm, preferably 0.2nm-200nm; Preferably, the morphology of the lithium-philic active site includes at least one of a one-dimensional point, a one-dimensional rod, a two-dimensional sheet, and a three-dimensional structure; Preferably, the lithium-philic active sites include at least one of magnesium, zinc, nickel, aluminum, silver, gold, molybdenum, lead, tin, bismuth, palladium, ruthenium, iridium, platinum, cerium, indium, silicon, carbon and their respective oxides, sulfides, halides and nitrides.

4. The negative electrode sheet according to claim 1 or 2, characterized in that: The lithium-philic active layer also includes a first conductive material and a binder; Preferably, the mass ratio of the first conductive material to the lithium-philic active site is (1-99):1; Preferably, the first conductive material includes at least one of conductive graphite, conductive carbon black, acetylene black, Ketjen black, carbon fiber, single-walled carbon nanotubes, multi-walled carbon nanotubes, polyethylene dioxythiophene, polystyrene sulfonic acid, lithium polystyrene sulfonate, sodium polystyrene sulfonate, graphene, fullerene, silicon carbide, calcium carbide, boron carbide, vanadium carbide, magnesium carbide, titanium carbide, zirconium carbide, tantalum carbide, tungsten carbide and niobium carbide; Preferably, the binder includes at least one of polyvinylidene fluoride, polyvinyl alcohol, polytetrafluoroethylene, sodium hydroxymethyl cellulose, styrene-butadiene rubber, nitrile rubber, styrene-butadiene-styrene copolymer, polyacrylic acid and lithium polyacrylate.

5. The negative electrode sheet according to claim 1 or 2, characterized in that: The negative electrode plate further includes a lithium metal layer, and the lithium metal layer is arranged on a side of the lithium-philic active layer away from the current collector.

6. The negative electrode sheet according to claim 1 or 2, characterized in that: The negative electrode plate further comprises an intermediate composite layer, and the intermediate composite layer is arranged on a side of the lithium-philic active layer away from the current collector.

7. The negative electrode sheet according to claim 6, characterized in that: The thickness of the intermediate composite layer is 10 μm-100 μm; Preferably, the intermediate composite layer includes at least one of reticulated glassy carbon, etherified reticulated cellulose, cellulose, lignin, ether lignin, chitosan, alginic acid, lithium alginate, sodium alginate, graphite, graphene, hard carbon, soft carbon, fullerene, elemental silicon, silicon-oxygen material, silicon-carbon material, silicon-nitrogen material, silicon-based alloy, elemental tin, tin-based alloy, lithium metal, lithium-based alloy, lithium-titanium oxide, transition metal oxide, transition metal sulfide, second conductive material, porous carbon material, carbon molecular sieve, mesoporous material, metal organic framework compound, covalent organic framework material, zeolite imidazolate framework structure material, 6-amino-1-hexanol-polyacrylic acid, hydroxyethylethylenediamine-polyacrylic acid, diglycolamine-polyacrylic acid ion cross-linked polymer, 5-amino-1-pentanol-polyacrylic acid, 4-amino-1-butanol-polyacrylic acid, N,N-bis(2-hydroxyethyl)ethylenediamine-polyacrylic acid and solid electrolyte; Preferably, the transition metal oxide comprises a tin oxide compound; Preferably, the second conductive material includes at least one of conductive graphite, conductive carbon black, acetylene black, Ketjen black, carbon fiber, single-walled carbon nanotubes, multi-walled carbon nanotubes, polyethylene dioxythiophene, polystyrene sulfonic acid, lithium polystyrene sulfonate, sodium polystyrene sulfonate, graphene, fullerene, silicon carbide, calcium carbide, boron carbide, vanadium carbide, magnesium carbide, titanium carbide, zirconium carbide, tantalum carbide, tungsten carbide and niobium carbide.

8. The negative electrode sheet according to claim 6, characterized in that: The negative electrode plate further comprises a solid electrolyte layer, and the solid electrolyte layer is arranged on a side of the intermediate composite layer away from the lithium-philic active layer.

9. A method for preparing the negative electrode sheet according to any one of claims 1 to 8, characterized in that: The method comprises: A lithium-philic active layer is prepared on at least one side of the current collector, wherein the lithium-philic active layer includes a lithium-philic active site, and a functional group is grafted on the lithium-philic active site, wherein the functional group includes at least one of a silicon-containing functional group, a nitrogen-containing functional group, a sulfur-containing functional group and a boron-containing functional group.

10. The method according to claim 9, characterized in that The step of preparing a lithium-philic active layer on at least one side of the current collector comprises: The lithium-philic active site precursor, the functional group precursor, the reducing agent, the conductive material, the binder, the dispersant and the solvent are mixed and subjected to a reduction reaction to obtain a first precursor solution; The first precursor solution is introduced into at least one side of the current collector to form the lithium-philic active layer.

11. The method according to claim 9, characterized in that The step of preparing a lithium-philic active layer on at least one side of the current collector comprises: The lithium-philic active site precursor, the functional group precursor, the reducing agent, the conductive material, the binder, the dispersant and the solvent are mixed to perform a first reduction reaction to obtain a second precursor solution; The second precursor solution is introduced into at least one side of the current collector to perform a second reduction reaction to form the lithium-philic active layer.

12. The method according to claim 10 or 11, characterized in that: Based on the total mass of the first precursor liquid, the mass proportion of the binder is 1%-10%; Preferably, based on the total mass of the second precursor liquid, the mass proportion of the binder is 1%-10%; Preferably, the lithium-philic active site precursor includes at least one of a soluble magnesium source, a soluble zinc source, a soluble nickel source, a soluble aluminum source, a soluble silver source, a soluble gold source, a soluble molybdenum source, a soluble lead source, a soluble tin source, a soluble bismuth source, a soluble palladium source, a soluble ruthenium source, a soluble iridium source, a soluble platinum source, a soluble cerium source, a soluble indium source, a soluble silicon source and a soluble carbon source; Preferably, the soluble silver source comprises at least one of silver nitrate, silver sulfate, silver fluoride, silver perchlorate and silver acetate; Preferably, the reducing agent comprises at least one of zinc powder, glucose, hydrazine hydrate, dodecyltetraethylene glycol ether, dimethylamine-borane, polyamide, lithium citrate and sodium citrate; Preferably, the dispersant comprises at least one of polyvinyl pyrrolidone, aniline, sodium naphthalene formaldehyde sulfonate, dihexadecyl pyridinium dithiophosphate, polyacrylic acid, cysteine ​​and polyvinyl epoxy nonphenyl ether; Preferably, the introducing method includes at least one of gravure roller, coating, spraying and chemical vapor deposition.

13. The method according to claim 11, characterized in that The temperature of the first reduction reaction is 80°C-300°C; Preferably, the first reduction reaction time is 3h-10h; Preferably, the second reduction reaction comprises at least one of liquid phase reduction and ultraviolet reduction.

14. The method according to claim 9, characterized in that The method further comprises: preparing the lithium metal layer on a side of the lithium-philic active layer away from the current collector; Preferably, the preparation method of the lithium metal layer comprises at least one of electrochemical deposition, evaporation and continuous rolling; Preferably, the temperature of the electrochemical deposition is -15°C-60°C, preferably 2°C-20°C.

15. The method according to claim 9, characterized in that The method further comprises: preparing the intermediate composite layer on a side of the lithium-philic active layer away from the current collector; Preferably, the preparation method of the intermediate composite layer includes at least one of coating and spraying; Preferably, the method further comprises: preparing a solid electrolyte layer on a side of the intermediate composite layer away from the lithium-philic active layer.

16. A lithium battery, characterized in that: The lithium battery comprises the negative electrode sheet according to any one of claims 1 to 8 or the negative electrode sheet prepared by the method according to any one of claims 9 to 15.

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