Composite material and preparation method thereof, cathode-free current collector and battery

Abstract

The invention relates to the technical field of batteries, in particular to a composite material and a preparation method thereof, a cathode-free current collector and a battery. The provided composite material comprises an inner core, a first coating layer and a second coating layer, the inner core comprises metal, and the inner core is of a frame structure; the first coating layer coats at least part of the surface of the inner core, and the first coating layer comprises a conductive polymer; the second coating layer coats at least part of the surface of the first coating layer, and the second coating layer comprises a ceramic material. The preparation method of the composite material comprises the following steps: mixing a porous template agent with a metal compound solution, adding a reducing agent, and carrying out first drying to obtain an inner core with a frame structure; coating a slurry containing a conductive polymer on the surface of the core to form a first coating layer; and coating slurry containing a ceramic material on the surface of the first coating layer to form a second coating layer. According to the invention, the deposition uniformity of lithium ions can be improved, and the safety performance of the lithium battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular, to a composite material, a preparation method thereof, a current collector without a negative electrode, and a battery. Background Art

[0002] In order to improve the energy density of batteries (such as lithium batteries), more and more research efforts have been devoted to the weight reduction design of batteries. Since the structure without a negative electrode does not require negative electrode active materials, the mass of the battery can be greatly reduced, thereby improving the energy density of the lithium battery. However, the current battery with a structure without a negative electrode faces a serious problem, that is, without the intercalation of lithium into the negative electrode active material, where should the lithium ions released from the positive electrode go. Although the conventional copper foil negative electrode can deposit lithium, it faces the problems of uneven lithium deposition, formation of lithium dendrites, piercing of the separator, contact short circuit between the positive and negative electrodes, and the risk of triggering safety problems. Therefore, how to solve the problem of uneven lithium deposition in the battery with a structure without a negative electrode is one of the key points in the application of the structure without a negative electrode.

[0003] In view of this, the present application is specifically proposed. Summary of the Invention

[0004] In view of this, the present invention aims to at least partly solve one of the technical problems in the related art. For this purpose, the present invention provides a composite material, a preparation method thereof, a current collector without a negative electrode, and a battery, which are beneficial to improving the uniformity of lithium ion deposition and alleviating the problem of lithium dendrites.

[0005] In order to solve the above technical problems, the present application is implemented as follows: According to one aspect of the present application, the present application provides a composite material, which includes: A core, the core includes a metal, and the core has a framework structure; A first coating layer, the first coating layer coats at least part of the surface of the core, and the first coating layer includes a conductive polymer; and A second coating layer, the second coating layer coats at least part of the surface of the first coating layer, and the second coating layer includes a ceramic material.

[0006] In any embodiment, the metal includes at least one of transition metals or post-transition metals.

[0007] In any embodiment, the metal includes at least one of copper, tin, silver or zinc.

[0008] In any embodiment, the core further includes a first binder.

[0009] In any embodiment, the mass ratio of the metal to the first binder is (95-98):(2-5).

[0010] In any embodiment, the first binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide or polyamide.

[0011] In any embodiment, the pore diameter of the pores in the frame structure ranges from 100 nm to 500 nm. In any embodiment, the porosity of the core is 20% to 50%.

[0012] In any embodiment, the average particle size of the core ranges from 2 μm to 5 μm.

[0013] In any embodiment, the conductive polymer includes at least one of conductive polyimide, conductive polyaniline or conductive polypyrrole.

[0014] In any embodiment, the first coating layer further includes a second binder.

[0015] In any embodiment, the mass ratio of the conductive polymer to the second binder is (80 to 90):(10 to 20).

[0016] In any embodiment, the second binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide or polyamide.

[0017] In any embodiment, the average particle size of the conductive polymer ranges from 100 nm to 500 nm.

[0018] In any embodiment, the thickness of the first coating layer is 2 μm to 5 μm.

[0019] In any embodiment, the ceramic material includes at least one of alumina, zirconia, aluminum nitride, silicon nitride, magnesium oxide, tin oxide or titanium oxide.

[0020] In any embodiment, the second coating layer further includes a third binder.

[0021] In any embodiment, the mass ratio of the ceramic material to the third binder is (80 to 90):(10 to 20).

[0022] In any embodiment, the third binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide or polyamide.

[0023] In any embodiment, the second coating layer has a porous structure.

[0024] In any embodiment, the porosity of the second coating layer is 5% to 20%.

[0025] In any embodiment, the thickness of the second coating layer is 2 μm to 5 μm.

[0026] According to another aspect of the present application, the present application provides a method for preparing a composite material, the method comprising the following steps: Mix a porous templating agent with a metal compound solution, add a reducing agent, and then perform a first drying to obtain a core with a framework structure; Coat a slurry containing a conductive polymer on the surface of the core to form a first coating layer on at least a part of the surface of the core; Coat a slurry containing a ceramic material on the surface of the first coating layer to form a second coating layer on at least a part of the surface of the first coating layer.

[0027] In any embodiment, the preparation of the porous templating agent includes: grinding a templating agent and a pore-forming agent to obtain particles with an average particle size of 100 nm to 500 nm; mixing the particles with a first binder and a first solvent evenly to obtain a slurry; coating the slurry on a substrate to form a film, and after a second drying and pulverization treatment, obtaining the porous templating agent.

[0028] In any embodiment, the average particle size range of the porous templating agent is 500 nm to 1000 nm.

[0029] In any embodiment, the templating agent includes at least one of polyethylene, polyethylene glycol, polyvinylpyrrolidone or cetyltrimethylammonium bromide.

[0030] In any embodiment, the pore-forming agent includes at least one of ammonium bicarbonate, ammonium carbonate, ammonium nitrate or ammonium sulfate.

[0031] In any embodiment, the mass ratio of the first binder, the templating agent and the pore-forming agent is (60 to 80):(10 to 20):(10 to 20).

[0032] In any embodiment, the first solvent includes at least one of N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide or water.

[0033] In any embodiment, the temperature of the second drying is 60°C to 100°C.

[0034] In any embodiment, mixing the porous template agent with the metal compound solution includes: immersing the porous template agent in the metal compound solution for 2 h to 4 h.

[0035] In any embodiment, the metal ions in the metal compound solution include at least one of copper ions, tin ions, silver ions or zinc ions.

[0036] In any embodiment, the anions in the metal compound solution include at least one of nitrate, sulfate, chloride or acetate.

[0037] In any embodiment, the reducing agent includes at least one of iron, zinc or hydrazine hydrate.

[0038] In any embodiment, after the first drying, it further includes: immersing the porous template agent with metal deposition after the first drying in a benzene solvent for 4 h to 12 h, followed by washing and third drying to obtain the core with a framework structure.

[0039] In any embodiment, the temperature of the first drying is 60°C to 100°C.

[0040] In any embodiment, the temperature of the third drying is 60°C to 100°C.

[0041] In any embodiment, the slurry containing the conductive polymer contains a conductive polymer, a second binder and a second solvent.

[0042] In any embodiment, the mass ratio of the conductive polymer to the second binder is (80 - 90):(10 - 20).

[0043] In any embodiment, the second solvent includes at least one of N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide or water.

[0044] In any embodiment, the average particle size range of the conductive polymer is 100 nm to 500 nm.

[0045] In any embodiment, after coating the slurry containing the conductive polymer on the surface of the core, fourth drying is carried out, and the temperature of the fourth drying is 60°C to 100°C.

[0046] In any embodiment, the slurry containing ceramics contains a ceramic material, a third binder and a third solvent.

[0047] In any embodiment, the ceramic-containing slurry further includes a pore-forming agent.

[0048] In any embodiment, the mass ratio of the ceramic material, the pore-forming agent, and the third binder is (70-80):(10-20):(10-20).

[0049] In any embodiment, the third solvent includes at least one of N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide, or water.

[0050] In any embodiment, after the slurry containing the ceramic material is coated on the surface of the first coating layer, heat treatment is performed. The temperature of the heat treatment is 100°C to 150°C, and the time is 4h to 8h.

[0051] According to another aspect of the present application, the present application provides a current collector-free electrode, which includes a substrate and a coating provided on at least one surface of the substrate. The coating includes the composite material as described above, or includes the composite material prepared by the preparation method as described above.

[0052] In any embodiment, the coating further includes a fourth binder and a conductive agent.

[0053] In any embodiment, the fourth binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide, or polyamide.

[0054] In any embodiment, the conductive agent includes at least one of conductive carbon black, conductive graphite, carbon nanotubes, carbon fibers, or graphene.

[0055] In any embodiment, the mass ratio of the composite material, the fourth binder, and the conductive agent is (70-80):(10-20):(10-20).

[0056] In any embodiment, the substrate includes a copper-based substrate or a composite substrate, and the composite substrate includes a substrate formed by the composite of a polymer material and a metal.

[0057] In any embodiment, the thickness of the coating is 2μm to 10μm.

[0058] According to still another aspect of the present application, the present application provides a battery, which includes the composite material as described above, or includes the composite material prepared by the preparation method as described above, or includes the current collector-free electrode as described above.

[0059] Implementing the technical solution of the present invention has at least the following beneficial effects: In the embodiments of the present application, the provided composite material can be applied to an anode-free battery structure, such as an anode-free current collector of an anode-free lithium battery. By providing a core of a metal material, the metal can form a framework structure, which can increase its specific surface area, improve the affinity with active ions such as lithium ions, and promote the deposition of lithium ions. Moreover, a first coating layer containing a conductive polymer is provided on the surface of the core, and the physical adsorption of the conductive polymer can be utilized to improve the directional transport ability of lithium ions and further improve the uniformity of lithium ion deposition. At the same time, a second coating layer containing a ceramic material is provided on the surface of the first coating layer, which can stabilize the first coating layer containing the conductive polymer by using the second coating layer containing the ceramic material, and can also inhibit the excessive growth of lithium dendrites and improve the safety performance by using the second coating layer. Therefore, the composite material is not only beneficial to improving the uniformity of lithium ion deposition, but also can improve the safety performance of the lithium battery, and has good application prospects in the field of anode-free batteries.

[0060] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 The figure shows a schematic structural diagram of a composite material provided by an embodiment of the present invention.

[0062] DESCRIPTION OF THE REFERENCE NUMERALS 10 - Core; 101 - Hole (void); 20 - First coating layer; 30 - Second coating layer. DETAILED DESCRIPTION

[0063] The following will further elaborate on the present application in conjunction with specific embodiments. It should be understood that these embodiments of the present application are only used to illustrate the present application and not to limit the scope of the present application.

[0064] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values or individual point values of each range, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0065] If there is no special description, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution. If there is no special description, all technical features and optional technical features of the present application can be combined with each other to form a new technical solution.

[0066] Unless otherwise specified, all steps of this application can be carried out sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) carried out sequentially, or may also include steps (b) and (a) carried out sequentially. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may also include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0067] Unless otherwise specified, the terms "comprising" and "including" mentioned in this application mean open-ended, and can also be closed-ended. For example, the terms "comprising" and "including" can mean that other components not listed may also be included or comprised, or may only include or comprise the listed components.

[0068] Generally, a non-negative electrode battery refers to a battery "without negative electrode active material". By not using negative electrode active material, the energy density of the battery can be improved. The technical principle of the non-negative electrode battery is that during formation charging or the first charging process of the battery, lithium in the positive electrode is deposited on the negative electrode current collector. However, in related technologies, there are problems with lithium dendrites caused by uneven deposition of lithium in non-negative electrode batteries. The formed lithium dendrites are likely to pierce the separator, causing contact short circuit between the positive and negative electrodes, and further leading to safety problems or risks of affecting the cycle life of the battery. Therefore, how to solve the problem of uneven lithium deposition in the non-negative electrode battery structure is one of the key points in the application of the non-negative electrode structure. Based on this, some research and improvements have been made on the non-negative electrode battery structure in related technologies. For example, the patent with publication number CN113013417A discloses a non-negative electrode structure, which coats an electronically conductive layer and an ionically conductive layer on the outer layer of the traditional negative electrode material. Although this method can accommodate the lithium source released from the positive electrode, this solution uses the method of directly immersing the copper foil in the ionic coating glue solution. This coating has no large pores, so it hinders the deposition rate of lithium ions on the surface of the copper foil, and the efficiency of depositing lithium is low. Seriously, it may cause lithium dendrites to pierce the separator and cause short circuit due to the untimely deposition of lithium ions (high-rate charging) on the surface of its coating; moreover, the preparation of the ionically conductive layer is difficult, and the quality of the traditional negative electrode metal substrate is large, affecting the energy density of the battery. Another example is that the patent with publication number CN116581361A discloses a non-negative electrode structure, which provides a lithium intercalation space and avoids direct reaction with the electrolyte by using a method of combining a lithium titanate layer for lithium intercalation and a solid electrolyte. However, currently, the solid electrolyte has problems of low ion transport rate and interface contact, affecting the power performance of the battery, and the setting of the lithium titanate layer also brings weight gain, which is not conducive to the improvement of the energy density of the non-negative electrode battery.

[0069] In view of this, the technical solution of the embodiment of the present application provides a composite material and a preparation method of the composite material. The composite material can be applied in a lithium metal anode-free battery, such as in the current collector of a lithium metal anode-free battery (the negative current collector of a lithium metal anode-free battery), and a lithium metal anode-free current collector and a battery containing the composite material. The technical solution of the embodiment of the present application can alleviate the problem of lithium dendrites in the existing lithium metal anode-free battery, achieve the purpose of enhancing the uniformity of lithium deposition, and improving the safety performance and cycle life of the lithium metal anode-free battery. The description of the specific technical solution is as follows.

[0070] [Composite Material] Please refer to Figure 1 As shown, in some embodiments, a composite material is provided, which includes: A core 10, the core 10 includes a metal, and the core 10 has a framework structure; A first coating layer 20, the first coating layer 20 coats at least part of the surface of the core 10, and the first coating layer 20 includes a conductive polymer; and A second coating layer 30, the second coating layer 30 coats at least part of the surface of the first coating layer 20, and the second coating layer 30 includes a ceramic material.

[0071] It should be noted that in the present application, the term "coating" is not limited to direct coating, but also includes indirect coating. For example, when the first coating layer 20 coats the core 10, there may be no other structure between the first coating layer 20 and the outer surface of the core 10, or there may be one or more other structures between the first coating layer 20 and the outer surface of the core 10. Preferably, there is no other structure between the first coating layer 20 and the outer surface of the core 10; in this way, it is more beneficial to the uniformity of the deposition of active ions such as lithium ions and improves the directional transport ability of active ions such as lithium ions. Similarly, when the second coating layer 30 coats the first coating layer 20, there may be no other structure between the second coating layer 30 and the outer surface of the first coating layer 20, or there may be one or more other structures between the second coating layer 30 and the outer surface of the first coating layer 20; in this way, it is more beneficial to improve the uniformity of the deposition of active ions such as lithium ions and improve the stability of the structure.

[0072] The first coating layer 20 is formed on or coats at least part of the surface of the inner core 10, which can protect or further improve the inner core 10, can be used to improve the electrical conductivity of the composite material, and can further improve the uniformity of lithium ion deposition. The first coating layer 20 being formed on at least part of the surface of the inner core 10 means that the first coating layer 20 can completely encapsulate the inner core 10 within the first coating layer 20, or it can also be that the first coating layer 20 only coats a part of the outer surface of the inner core; that is, the first coating layer 20 can completely coat the inner core 10 or can coat a part of the surface of the inner core 10, preferably completely coat; in this way, it can better play a protective or improving role.

[0073] The second coating layer 30 is formed on or coats at least part of the surface of the first coating layer 20, which can protect and improve the inner core 10 and the first coating layer 20, can be used to improve the structural stability, enhance the electrochemical performance of the composite material, and can also inhibit the excessive growth of lithium dendrites and further improve the safety performance. The second coating layer 30 being formed on at least part of the surface of the first coating layer 20 means that the second coating layer 30 can completely encapsulate the first coating layer 20 within the second coating layer 30, or it can also be that the second coating layer 30 only coats a part of the outer surface of the first coating layer 20; that is, the second coating layer 30 can completely coat the first coating layer 20 or can coat a part of the surface of the first coating layer 20, preferably completely coat; in this way, it is more conducive to improving the structural stability and better plays a protective or improving role.

[0074] The provided composite material has a core-shell structure, which includes an inner core 10 and an outer shell. The inner core 10 is made of a metal material, and the metal can form a framework structure, such that the inner core is an inner core 10 with a porous 101 structure; the outer shell includes a first coating layer 20 and a second coating layer 30. The first coating layer 20 contains a conductive polymer, and the second coating layer 30 contains a ceramic material. Thus, by arranging an active metal in the inner core 10 and forming a framework structure, the specific surface area can be increased, the binding ability with active ions such as lithium ions can be improved, and the deposition of lithium ions can be promoted; and by arranging the first coating layer 20 containing a conductive polymer on the surface of the inner core 10, the physical adsorption of the conductive polymer can be utilized to improve the lithium ion directional transport ability and further improve the uniformity of lithium ion deposition; at the same time, by arranging the second coating layer 30 containing a ceramic material on the surface of the first coating layer 20, the first coating layer 20 containing a conductive polymer can be stabilized by the second coating layer 30 containing a ceramic material, and the second coating layer 30 can also be used to inhibit the excessive growth of lithium dendrites and improve the safety performance. In some preferred embodiments, the second coating layer 30 also has a porous structure. By utilizing the porous property of the second coating layer 30, the diffusion of lithium ions into the composite material can be improved, and the uniformity of lithium ion deposition can be improved.

[0075] Thus, by sequentially providing a first coating layer 20 and a second coating layer 30 on the surface of the metal core 10 with a frame structure, the composite material adopts a multi-layer coating structure. Through reasonable structural design, not only the structural stability of the composite material is improved, the conductivity of the composite material is improved, but also the deposition uniformity of lithium ions is facilitated, the safety performance of the lithium battery can be improved, and it has good application prospects in the field of lithium-free batteries.

[0076] The inventor of the present application has found through in-depth research that when the composite material of the present application meets the above design conditions, if it also optionally meets one or more of the following conditions, the performance of the composite material can be further improved.

[0077] In the embodiments of the present invention, the provided high-performance composite material can be applied in a lithium-free battery, such as in the lithium-free current collector of a lithium-free battery, as a coating material. It includes a core, a first coating layer, and a second coating layer from the inside to the outside. The core therein can also be called a metal core, the first coating layer can also be called a conductive polymer layer, and the second coating layer can also be called a porous ceramic coating. The composite material mainly promotes the uniform deposition of lithium ions through the electron adsorption of active metals to lithium ions and the physical adsorption of conductive polymers to lithium ions, etc.; the ceramic coating is used to stabilize the structure and inhibit the growth of lithium dendrites to improve safety performance.

[0078] Among them, in some embodiments, in the core 10, the metal includes at least one of transition metals or post-transition metals.

[0079] In the present application, transition metals mainly refer to the elements in the d-block (Groups 3 to 12) of the periodic table, and the valence electrons of their atoms are filled in the d-orbitals (such as iron, copper, zinc, etc.). Transition metals have incompletely filled d-orbitals (or can form cations with unfilled d-orbitals).

[0080] Post-transition metals generally refer to the main group metals on the right side of transition metals (d-block) in the periodic table, covering some metal elements in Groups 13 to 15 (ⅢA to ⅤA). These elements have physical properties similar to metals (such as ductility, conductivity), but their chemical behavior is between typical metals and metalloids (such as arsenic, antimony). Exemplarily, common post-transition metals include: aluminum (Al), gallium (Ga), indium (In), tin (Sn), lead (Pb), bismuth (Bi), etc.

[0081] The core metal material in the composite material of the present application can be selected from transition metals, or post-transition metals, or one or more of transition metals and post-transition metals. In this way, through the electron adsorption of these active metals to lithium ions and by modifying to increase their specific surface area and provide the binding ability with lithium ions, the deposition of lithium ions can be promoted.

[0082] In some preferred embodiments, the metal includes, but is not limited to, any one or a combination of at least two of copper (Cu), tin (Sn), silver (Ag), or zinc (Zn); among them, copper (Cu), silver (Ag), and zinc (Zn) belong to transition metals, and tin (Sn) belongs to post-transition metals.

[0083] Several active metals such as the above-mentioned Cu, Sn, Ag, and Zn not only have a wide source and are easy to obtain, but also have strong lithiophilicity, which is more conducive to promoting the uniform deposition of lithium ions, is beneficial to improving the lithium dendrite problem, and further is more conducive to improving the safety of the battery.

[0084] In some embodiments, the metal core 10 is modified to have the characteristics of pores 101, that is, after being modified, the metal forms a framework structure in the form of pores 101; among them, the modification treatment can be, for example, adding pore-forming agents, templating agents and other components during the preparation process, and decomposing or volatilizing the pore-forming agents, templating agents, etc. through heat treatment to form a porous structure.

[0085] Optionally, the pore diameter of the pores 101 in the framework structure of the pores 101 ranges from 100 nm to 500 nm; exemplarily, the pore size of the framework structure of the pores 101 can be any point value among 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm or the range value between any two of them.

[0086] During the preparation of the above-mentioned metal core 10, a porous templating agent is added, and the porous templating agent will be decomposed by the solvent in the subsequent treatment, and then a framework structure in the form of pores is formed, that is, these pores (holes) are left after the porous templating agent is digested. Therefore, the size of the pore diameter is related to the added porous templating agent, and for example, the size of the pore diameter can be adapted to the particle diameter of the added porous templating agent. In the present application, by limiting the pore diameter range to 100 nm to 500 nm, certain structural strength and compaction density can be satisfied, which is beneficial to increasing the specific surface area and the binding ability with lithium ions, and further is beneficial to promoting the uniform deposition of lithium ions; if the pore diameter is too large, the structural strength of the composite material will be reduced and the compaction density will be reduced; if the pore diameter is too small, the effect of promoting the uniform deposition of lithium ions will be reduced.

[0087] Optionally, the porosity of the core 10 with the framework structure of the pores 101 is 20% to 50%; exemplarily, its porosity can be any point value among 20%, 25%, 30%, 35%, 40%, 45%, 50% or the range value between any two of them.

[0088] In the present application, by making the porosity of the core 10 within the range of 20% to 50%, on the basis of meeting a certain structural strength, the compaction density can be increased, the specific surface area can be increased, multiple particles can also be accommodated, and sufficient pores can be reserved for dip coating deposition, thereby facilitating the uniform deposition of lithium ions.

[0089] In some embodiments, the core 10 further includes a first binder; that is, the core is mainly composed of a metal and a first binder, wherein the metal has a porous framework structure, and the first binder component may exist in the pores or gaps of the porous framework structure, that is, the first binder can adhere to at least part of the pores of the porous framework structure.

[0090] Considering that the amount of the first binder itself is small and the density is low, optionally, the mass ratio of the metal to the first binder is (95 to 98):(2 to 5); exemplarily, the mass ratio of the metal to the first binder is any one of 95:5, 96:4, 97:3, 97.5:2.5, 98:2 or the range value between any two of them.

[0091] Thus, by making the ratio of the metal to the first binder within the above range, the electron adsorption property of the metal can be ensured, and the core can also have a certain adhesiveness, improving the connection strength between the core and the first coating layer.

[0092] Optionally, the first binder includes, but is not limited to, any one or a combination of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC-Na), potassium carboxymethyl cellulose (CMC-K), styrene-butadiene rubber (SBR), polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide or polyamide.

[0093] The first binder in the above core can adopt various binders known in the art, preferably selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC-Na), styrene-butadiene rubber (SBR), etc., which have a wider source, are more easily obtained, and have better application effects.

[0094] In some embodiments, the average particle size range of the core is 2 μm to 5 μm. Exemplarily, the average particle size of the core can be any one of 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm or the range value between any two of them.

[0095] By making the average particle size of the core within the above range, multiple particles can be accommodated, and sufficient pores can be reserved for dip coating deposition, which is not only beneficial to processing and preparation, but also beneficial to promoting the uniform deposition of lithium ions.

[0096] In some embodiments, in the first coating layer 20, the conductive polymer includes, but is not limited to, any one or a combination of conductive polyimide, conductive polyaniline, or conductive polypyrrole.

[0097] By coating the above-mentioned several conductive polymers on the surface of the inner core, not only can the conductivity be improved, but also the uniform deposition of lithium ions can be jointly promoted through the electron adsorption of lithium ions by active metals and the physical adsorption of lithium ions by conductive polymers. Moreover, the above-mentioned several conductive polymers have a certain physical adsorption property, which can improve the directional transport ability of lithium ions and further improve the uniformity of lithium ion deposition.

[0098] In some embodiments, the average particle size range of the conductive polymer is 100 nm to 500 nm. Exemplarily, the average particle size of the conductive polymer can be any one point value of 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm or the range value between any two of them. The particle size of the conductive polymer within this range helps to ensure good processing performance of the composite material and is also beneficial to improving the electrochemical performance of the prepared composite material.

[0099] In some embodiments, the first coating layer 20 further includes a second binder; that is, the first coating layer is mainly composed of a conductive polymer and a second binder.

[0100] Optionally, the mass ratio of the conductive polymer to the second binder is (80 - 90):(10 - 20); Exemplarily, the mass ratio of the conductive polymer to the second binder is any one point value of 80:20, 82:18, 85:15, 88:12, 90:10 or the range value between any two of them.

[0101] Thus, by making the ratio of the conductive polymer to the second binder within the above range, it is possible to avoid the excessive addition amount of the second binder from affecting the performance of the conductive polymer, and at the same time meet the bonding requirements of the first coating layer, so that the first coating layer has a certain adhesiveness and improves the connection strength between the inner core and the first coating layer and between the first coating layer and the second coating layer.

[0102] Optionally, the second binder includes, but is not limited to, any one or a combination of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC-Na), potassium carboxymethyl cellulose (CMC-K), styrene-butadiene rubber (SBR), polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide, or polyamide.

[0103] The second binder in the first coating layer 20 described above can be various binders known in the art, preferably selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC-Na), styrene-butadiene rubber (SBR), etc. These binders have a wider source, are more easily obtained, and have better application effects.

[0104] In this application, the types of the first binder and the second binder can be the same or different, and there is no limitation in this regard.

[0105] In some embodiments, the thickness of the first coating layer 20 is 2 μm to 5 μm. Exemplarily, the thickness of this first coating layer can be any point value among 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm or the range value between any two of them.

[0106] The thickness of the first coating layer can be adjusted according to the size of the core. A suitable thickness of the first coating layer can not only ensure that the composite material has good processing performance, but also avoid excessive thickness and too much first coating material increasing the battery impedance or affecting the cycle performance of the battery cell, or can also avoid too thin thickness that is insufficient to effectively exert the modification effect of the first coating layer.

[0107] In some embodiments, in the second coating layer 30, the ceramic material includes, but is not limited to, any one or a combination of more than one of alumina, zirconia, aluminum nitride, silicon nitride, magnesium oxide, tin oxide or titanium oxide. Preferably, considering comprehensively factors such as raw material source, cost and use effect, it is more preferable to use these ceramic materials of alumina, zirconia, aluminum nitride and silicon nitride.

[0108] By coating the surface of the first coating layer with the above-mentioned several ceramic materials, the structural stability of the first coating layer can be improved, the first coating layer can be protected, the overall performance or structural stability of the composite material can be ensured, and the excessive growth of lithium dendrites can also be inhibited, thereby improving the safety performance.

[0109] In some embodiments, the second coating layer 30 further includes a third binder; that is, this second coating layer is mainly composed of a ceramic material and a third binder.

[0110] Optionally, the mass ratio of the ceramic material to the third binder is (80 - 90):(10 - 20); Exemplarily, the mass ratio of the ceramic material to the third binder is any point value among 80:20, 82:18, 85:15, 88:12, 90:10 or the range value between any two of them.

[0111] Thus, by making the ratio of the ceramic material and the third binder within the above range, it is possible to avoid the excessive addition of the third binder from affecting the performance of the ceramic material, and also meet the bonding requirements of the second coating layer, endowing the second coating layer with a certain adhesiveness, improving the connection strength between the first coating layer and the second coating layer, and ensuring the structural stability of the composite material.

[0112] Optionally, the third binder includes, but is not limited to, any one or a combination of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC-Na), potassium carboxymethyl cellulose (CMC-K), styrene-butadiene rubber (SBR), polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide, or polyamide.

[0113] The third binder in the second coating layer described above can adopt various binders known in the art, preferably selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC-Na), styrene-butadiene rubber (SBR), etc., which have a wider source, are more easily obtainable, and have better application effects.

[0114] In this application, the types of the first binder, the second binder, and the third binder can be the same or different, and no limitation is imposed thereon.

[0115] In some embodiments, the second coating layer 30 has a porous structure. The second coating layer of this application is a porous ceramic coating. By making the second coating layer have a porous structure, the porous properties can be utilized to improve the diffusion of lithium ions into the composite material and enhance the deposition uniformity of lithium ions.

[0116] In some embodiments, the porosity of the second coating layer is 5% - 20%. Exemplarily, the porosity of the second coating layer can be any one of the point values of 5%, 10%, 15%, 18%, 20% or the range values between any two of them.

[0117] By controlling the porosity of the second coating layer within the above suitable range, the diffusion of lithium ions into the composite material can be improved, and the structural strength can be ensured.

[0118] In some embodiments, the thickness of the second coating layer is 2μm - 5μm. Exemplarily, the thickness of the second coating layer can be any one of the point values of 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm or the range values between any two of them.

[0119] By controlling the thickness of the second coating layer within the above suitable range, it is possible to ensure that the composite material has good processing performance, and to avoid that the excessive thickness and excessive amount of the second coating material increase the battery impedance or affect the cycle performance of the battery core, or to avoid that the too thin thickness is not sufficient to effectively exert the modification effect of the second coating layer.

[0120] Therefore, for the composite material provided by the present application, an active metal is arranged in the inner core, and a porous framework structure is formed. By modification, its specific surface area is increased, the affinity with lithium ions is improved, and the deposition of lithium ions is promoted; a first coating layer containing a conductive polymer is arranged in the middle layer, and the physical adsorption property of the conductive polymer is utilized to improve the lithium ion directional transport ability and further improve the lithium ion deposition uniformity; a second coating layer including a porous ceramic material is arranged in the outermost layer. On the one hand, the ceramic coating layer, that is, the second coating layer, can stabilize the structure of the first coating layer. On the other hand, it can also inhibit the excessive growth of lithium dendrites and improve the safety performance. Moreover, the porous property of the second coating layer can improve the diffusion of lithium ions into the composite material. Through reasonable structural design, the present invention not only improves the lithium ion deposition uniformity, but also can improve the safety performance of the lithium battery. In addition, the preparation process of the composite material is simple, so it has good application prospects in the field of anode-free batteries.

[0121] [Preparation method of composite material] Correspondingly, in some embodiments, a preparation method of a composite material is provided, and the method includes the following steps: Mix a porous template agent with a metal compound solution, add a reducing agent, and then perform a first drying to obtain an inner core with a framework structure; Coat a slurry containing a conductive polymer on the surface of the inner core to form a first coating layer on at least part of the surface of the inner core; Coat a slurry containing a ceramic material on the surface of the first coating layer to form a second coating layer on at least part of the surface of the first coating layer.

[0122] The method provided by the present invention can first prepare a metal inner core, that is, an inner core with a porous framework structure, and then form a first coating layer containing a conductive polymer on the surface of the inner core, and then form a second coating layer containing a ceramic material on the surface of the first coating layer, thereby forming a composite material with a core-shell structure.

[0123] The preparation method provided by the embodiments of the present invention has simple process, convenient operation, strong feasibility and is easy to realize industrialization; the composite material prepared by this method is beneficial to improving the lithium ion deposition uniformity, alleviating the lithium dendrite problem, and further beneficial to improving the safety performance of the battery.

[0124] It should be understood that all the features and advantages described above for the "composite material" also apply to the "preparation method of the composite material", and will not be elaborated one by one here.

[0125] In some specific embodiments, the preparation method of the cathode lithium supplement includes the following steps (a) to (c): (a) Prepare the core.

[0126] In step (a), preparing the core includes: first preparing a porous templating agent, then mixing the porous templating agent with a metal compound solution, adding a reducing agent, and then performing a first drying to obtain a core with a framework structure.

[0127] During the preparation of the core in the present application, a porous templating agent is added, and the porous templating agent will be decomposed by a solvent in subsequent processing, thereby forming a porous framework structure, that is, holes are left after the porous templating agent is decomposed, making the core have a porous framework structure.

[0128] In some embodiments, in step (a), the preparation of the porous templating agent includes: Grind the templating agent and the pore-forming agent to obtain particles with an average particle size of 100 nm to 500 nm; Mix the particles, a first binder, and a first solvent evenly to obtain a slurry; Coat the slurry on a substrate to form a film, and after a second drying and pulverization treatment, obtain a porous templating agent.

[0129] As mentioned above, the particle size of the above-mentioned particles is adapted to the pore size of the framework structure. Particles of this size can form a pore structure of corresponding size. By limiting the average particle size range of the particles to 100 nm to 500 nm, certain structural strength and compaction density can be satisfied, which is beneficial to increasing the specific surface area and the binding ability with lithium ions, and thus is beneficial to promoting the uniform deposition of lithium ions; if the particle size is too large, the structural strength of the composite material will be reduced and the compaction density will be reduced; if the particle size is too small, the effect of promoting the uniform deposition of lithium ions will be reduced.

[0130] In any embodiment, after the above-mentioned pulverization treatment, particles with an average particle size of 500 nm to 1000 nm are obtained, that is, a porous templating agent is obtained; as an example, the average particle size of the porous templating agent can be any one of 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm or the range value between any two of them.

[0131] Optionally, the templating agent includes, but is not limited to, at least one of polyethylene, polyethylene glycol, polyvinylpyrrolidone, or cetyltrimethylammonium bromide. The templating agent can be a substance that can be dissolved by toluene solvent.

[0132] In some preferred embodiments, the template agent is selected from polyethylene. By selecting polyethylene as the template agent, it can be dissolved by toluene solvent in subsequent processing, thereby forming pores in the metal core.

[0133] Optionally, the pore-forming agent includes, but is not limited to, at least one of ammonium bicarbonate, ammonium carbonate, ammonium nitrate, or ammonium sulfate.

[0134] In some preferred embodiments, the pore-forming agent is selected from ammonium bicarbonate. By selecting ammonium bicarbonate as the pore-forming agent, it is easy to decompose and form a pore structure, thereby making the template agent form a porous template agent.

[0135] In some embodiments, in step (a), the mass ratio of the first binder, the template agent, and the pore-forming agent is (60-80):(10-20):(10-20); for example, the mass ratio of the first binder, the template agent, and the pore-forming agent is 60:20:20, 65:15:20, 65:18:17, 70:15:15, 75:12:13, 80:10:10, etc.

[0136] In some embodiments, in step (a), the first solvent includes, but is not limited to, at least one of N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), or water.

[0137] In some embodiments, in step (a), the temperature of the second drying is 60°C to 100°C; as an example, the temperature of the second drying can be any one of the point values of 60°C, 70°C, 80°C, 90°C, 100°C or the range value between any two of them; The temperature of the second drying can be selected and set according to the decomposition temperature of the pore-forming agent. For example, ammonium bicarbonate substances decompose when heated, generally above 60°C. Therefore, the temperature of the second drying is 60°C to 100°C to decompose the ammonium bicarbonate-based pore-forming agent in the mixed particles, that is, to obtain a porous template agent, such as obtaining porous polyethylene particles.

[0138] In some embodiments, in step (a), after preparing the porous template agent, the porous template agent is mixed with the metal compound solution, specifically including: immersing the porous template agent in the metal compound solution, and the immersion time is 2h to 4h; as an example, the immersion time can be any one of the point values of 2h, 2.5, 3h, 3.5h, 4h or the range value between any two of them.

[0139] By immersing the porous template agent in the metal compound for 2h to 4h, the porous template agent can be fully mixed with the metal compound solution, improving the mixing uniformity.

[0140] Optionally, the metal ions in the metal compound solution include at least one of copper ions, tin ions, silver ions or zinc ions. The metal ions can be one or more of transition metal ions or post-transition metal ions, preferably selected from any one or more combinations of copper ions, tin ions, silver ions or zinc ions. In this way, it has better lithium affinity and is beneficial to improving the uniformity of lithium ion deposition.

[0141] Optionally, the anions in the metal compound solution include at least one of nitrate, sulfate, chloride or acetate.

[0142] As an example, the metal compound solution can be solutions such as copper nitrate, tin nitrate, silver nitrate, zinc nitrate, copper sulfate, tin sulfate, silver sulfate, zinc sulfate, copper acetate, tin acetate, silver acetate, zinc acetate, etc.

[0143] In some embodiments, in step (a), after mixing the porous template agent with the metal compound solution, a reducing agent is added to the solution to reduce the metal in the metal compound solution. Among them, the reducing agent includes, but is not limited to, at least one of iron, zinc or hydrazine hydrate.

[0144] Thus, by adding the above-mentioned reducing agents to the solution, the metal in the metal compound can be reduced to obtain porous template agent microspheres with metal deposition, such as obtaining porous polyethylene microspheres with metal deposition.

[0145] In some embodiments, in step (a), after adding the reducing agent, a first drying is performed. The temperature of the first drying can be a conventional temperature. For example, the temperature of the first drying is 60°C to 100°C. Further, after the first drying, it further includes: soaking the metal-deposited porous template agent after the first drying in a benzene solvent for 4 h to 12 h, then performing washing and a third drying. The temperature of the third drying can also be a conventional temperature. For example, the temperature of the third drying is 60°C to 100°C to obtain a core with a framework structure; Optionally, the above-mentioned benzene solvent can be toluene, but not limited thereto, as long as it can be used to dissolve template agents such as polyethylene.

[0146] Thus, after soaking the metal-deposited porous template agent in a benzene solvent such as toluene, the porous template agent can be dissolved, that is, the porous template agent can be decomposed, and then a metal core with a porous framework structure is formed.

[0147] Exemplarily, step (a) specifically includes: grinding a templating agent (such as polyethylene, etc.) and a pore-forming agent (such as ammonium bicarbonate, etc.) to obtain particles with an average particle size of 100 nm to 500 nm; then mixing the particles with a first binder uniformly in a first solvent and stirring to obtain a slurry; wherein the mass ratio of the first binder, the templating agent, and the pore-forming agent is (60 - 80):(10 - 20):(10 - 20); coating the slurry on a substrate (the substrate mainly refers to a bottom plate that can support the coating and film formation of the slurry, for example, the substrate can be a glass plate, a plastic plate, etc.) to form a thin film, after the second drying, removing the thin film from the substrate, and then performing a pulverization treatment to obtain particles with a suitable particle size, that is, a porous templating agent is obtained.

[0148] Then, soak the porous templating agent in a solution containing metal ions, that is, a metal compound solution, for 2 h to 4 h, and then add a reducing agent such as iron, zinc, or hydrazine hydrate, etc. to the solution, and a metal-deposited porous templating agent can be obtained, such as obtaining metal-deposited porous polyethylene microspheres; then dry the metal-deposited porous templating agent and soak it in a benzene solvent such as toluene solvent for 4 h to 12 h, and then perform washing (such as water washing) and the third drying to obtain a porous framework-structured metal core.

[0149] In the present application, after the porous templating agent is soaked in a solution containing metal ions, the metal compound solution will penetrate into the interior of the porous templating agent such as porous polyethylene mixed particles along the pores, and then the corresponding metal ions can be reduced to metals through a reducing agent. Repeating the above operations multiple times, a metal layer with a certain thickness of deposition can be obtained, denoted as a metal-based core. In addition, in other embodiments, a metal core can also be obtained by means of gas-phase reduction, such as mixing porous polyethylene mixed particles soaked with metal salts with a reducing gas such as hydrogen, and metal can also be reduced to obtain a porous metal-based core.

[0150] (b) Prepare the first coating layer.

[0151] In step (b), preparing the first coating layer includes: first preparing a slurry containing a conductive polymer, and then coating the slurry containing the conductive polymer on the surface of the core to form a first coating layer on at least a part of the surface of the core.

[0152] In some embodiments, in step (b), the slurry containing the conductive polymer contains a conductive polymer, a second binder, and a second solvent.

[0153] Optionally, the mass ratio of the conductive polymer to the second binder is (80 - 90):(10 - 20); Optionally, the second solvent includes, but is not limited to, at least one of N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide, or water.

[0154] Optionally, the average particle size of the conductive polymer ranges from 100 nm to 500 nm; In some embodiments, in step (b), after coating the slurry containing the conductive polymer on the surface of the core, a fourth drying is carried out, and the temperature of the fourth drying is 60 °C to 100 °C.

[0155] Exemplarily, the above step (b) specifically includes: uniformly mixing a conductive polymer such as conductive polyimide with a suitable particle size, such as an average particle size ranging from 100 nm to 500 nm, and a second binder in a mass ratio of (80 - 90):(10 - 20) in a second solvent such as NMP, and then spraying the slurry onto the surface of the metal-based core obtained in step (a) by spray coating. After the fourth drying, a first coating layer is formed on the surface of the core.

[0156] (c) Prepare a second coating layer.

[0157] In step (c), preparing the second coating layer includes: first preparing a slurry containing a ceramic material, and then coating the slurry containing the ceramic material on the surface of the first coating layer to form a second coating layer on at least a part of the surface of the first coating layer.

[0158] In some embodiments, in step (c), the slurry containing the ceramic contains a ceramic material, a third binder, and a third solvent.

[0159] Optionally, the slurry containing the ceramic further includes a pore-forming agent; that is, the slurry containing the ceramic contains a ceramic material, a third binder, a pore-forming agent, and a third solvent. Among them, the pore-forming agent can be an ammonium bicarbonate-based pore-forming agent.

[0160] In some embodiments, in step (c), the mass ratio of the ceramic material, the pore-forming agent, and the third binder is (70 - 80):(10 - 20):(10 - 20).

[0161] Optionally, the third solvent includes, but is not limited to, at least one of N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide, or water; In some embodiments, in step (c), after coating the slurry containing the ceramic material on the surface of the first coating layer, a heat treatment is carried out, and the temperature of the heat treatment is 100 °C to 150 °C, and the time is 4 h to 8 h. As an example, the temperature of the heat treatment can be any one of the point values of 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C or the range value between any two of them; the time can be any one of the point values of 4 h, 5 h, 6 h, 7 h, 8 h or the range value between any two of them.

[0162] Exemplarily, step (c) specifically includes: uniformly mixing ceramic materials such as alumina ceramic materials, pore formers, and a third binder in a mass ratio of (70-80):(10-20):(10-20) in a third solvent such as NMP, and then spraying the slurry onto the surface of the material obtained in step (b) by means of spray coating. After heat treatment at 100°C to 150°C for 4h to 8h (such as standing for 4h to 8h in an environment of 100°C to 150°C), a second coating layer is formed on the surface of the first coating layer to obtain a composite material.

[0163] The preparation method of the composite material provided in the embodiments of the present application has a simple process, strong feasibility, high efficiency and environmental protection, and is easy to realize large-scale production.

[0164] [Anode-free current collector] Correspondingly, in some embodiments, an anode-free current collector is provided. The anode-free current collector includes a substrate and a coating provided on at least one surface of the substrate. The coating includes the aforementioned composite material or the composite material prepared by the aforementioned preparation method.

[0165] The anode-free current collector of the present application includes a substrate and a coating provided on at least one surface of the substrate. The coating contains the above composite material, so it can improve the uniformity of lithium ion deposition, inhibit the growth of lithium dendrites, and is beneficial to improving the safety of the battery.

[0166] The above coating can be provided on at least one surface of the substrate means that the coating can be provided on one surface of the substrate along its own thickness direction, or can be provided on two surfaces of the substrate along its own thickness direction. Here, the "surface" can be the entire area of the substrate or a partial area of the substrate. There is no special limitation in the present application as long as the purpose of the present application can be achieved.

[0167] Optionally, in this embodiment, the substrate has two surfaces opposite to each other in its own thickness direction, and the coating is provided on the two opposite surfaces of the substrate. It can be understood that in other embodiments, the coating can also be provided on any one of the two surfaces of the substrate. Preferably, when the coating is provided on one surface of the substrate, the coating is provided on the side close to the negative electrode.

[0168] In the present application, the substrate can be a copper-based substrate or a composite substrate. The composite substrate includes a substrate formed by the composite of a polymer material and a metal.

[0169] As an example, the substrate can be selected from conventional sheet-like metal foils applied in the field of anode current collectors, such as copper foils, porous copper foils, foam copper, etc. The sources are wide, the cost is low, and they are easy to obtain.

[0170] Alternatively, the substrate can also be a substrate formed by the composite of a polymer material and a metal. For example, the composite substrate can be formed by forming a metal material such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy on a substrate of a polymer material such as polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, and polystyrene.

[0171] In some embodiments, the coating further includes a fourth binder and a conductive agent, that is, the coating mainly includes a composite material, a fourth binder, and a conductive agent.

[0172] Optionally, the fourth binder includes, but is not limited to, at least one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide, or polyamide.

[0173] Optionally, the conductive agent includes, but is not limited to, at least one of conductive carbon black, conductive graphite, carbon nanotubes, carbon fibers, or graphene.

[0174] It should be noted that the fourth binder and the conductive agent are not limited to the substances listed above. Those that can be used in the coating of the battery and do not limit the purpose of the present invention, and other similar binders and conductive agents can also be used in the present invention.

[0175] Optionally, the mass ratio of the composite material, the fourth binder, and the conductive agent is (70 - 80):(10 - 20):(10 - 20). Exemplarily, the mass ratio of the composite material, the fourth binder, and the conductive agent is 70:15:15, 72:10:18, 75:10:15, 80:10:10, etc.

[0176] In some embodiments, the thickness of the coating is 2 μm to 10 μm. Exemplarily, the thickness of the coating can be any point value among 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or the range value between any two of them.

[0177] Optionally, the areal density of the coating can be 0.05 - 0.1 g / cm.

[0178] [Battery] In some embodiments, a battery is provided, which includes the above-mentioned current collector-free negative electrode; the battery further includes a positive electrode sheet, a separator, and an electrolyte; the separator is located between the positive electrode sheet and the current collector-free negative electrode.

[0179] The electrochemical cell can be a secondary battery, having high cycle performance and high safety. Specifically, the secondary battery can be specifically a lithium secondary battery.

[0180] The battery includes the above-mentioned current collector without a negative electrode provided by the embodiments of the present application. Therefore, the battery, such as a lithium-ion secondary battery, also has excellent electrochemical performance, such as long cycle life, good rate performance, etc.

[0181] The battery provided by the present application belongs to a battery without a negative electrode. Compared with conventional lithium-ion batteries using carbon materials or silicon materials as negative electrode active substances, the energy density of the battery can be greatly improved.

[0182] The battery provided by the present application uses the current collector without a negative electrode provided by the present application, which can induce uniform lithium deposition, reduce or avoid lithium dendrites, improve the safety performance of the battery, and also improve the cycle performance of the battery.

[0183] In the embodiments of the present application, in the battery, the specific materials, structures, etc. of the positive electrode sheet, separator, and electrolyte are not limited, and the components and structures known to those skilled in the art and applicable to secondary batteries can be selected, as long as the purpose of the present application can be achieved.

[0184] The battery of the present application further includes a packaging case for accommodating the positive electrode plate, separator, current collector (negative electrode current collector of the battery without a negative electrode), electrolyte, and other components known in the art in a lithium battery. The present application does not limit the above-mentioned other components. The present application has no special restrictions on the packaging case, and it can be a packaging case well-known in the art, as long as the purpose of the present application can be achieved.

[0185] The present invention has no special restrictions on the preparation method of the battery, and the technical solution of preparing the positive electrode material into a battery such as a secondary battery well-known to those skilled in the art can be adopted.

[0186] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application and should not be construed as a limitation to the present application. For those not specified in the embodiments in terms of specific technologies or conditions, they shall be carried out according to the technologies or conditions described in the literature in the art or according to the product specifications. For the reagents, materials, or instruments not specified in terms of the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0187] Example 1 1. Preparation of the composite material, including the following steps: (a) First, grind polyethylene (template agent) and ammonium bicarbonate (pore-forming agent) particles into particles with a particle size of about 200 nm. Subsequently, uniformly mix PVDF (the first binder), polyethylene particles, and ammonium bicarbonate in a ratio of 60:20:20 in the solvent NMP, stir into a slurry, coat the slurry on a substrate to form a film, remove the film after drying, and prepare particles with a particle size of about 800 nm through pulverization treatment, which are porous polyethylene particles.

[0188] Soak the above-mentioned porous polyethylene microsphere material in a stannous sulfate solution with a concentration of 0.1 mol / L for 4 h. Subsequently, add a hydrazine hydrate reducing agent to the solution to obtain porous polyethylene microspheres with tin metal deposition. After drying the porous polyethylene microspheres with metal deposition, soak them in a toluene solvent for 8 h to dissolve the polyethylene microspheres. After washing with water and drying, a porous metal-based core (tin-based core) is obtained. The porosity of this core is 40%.

[0189] (b)Prepare conductive polymer particles with a particle size of about 500 nm, such as conductive polyimide. Mix the conductive polymer and PVDF (the second binder) evenly in the solvent NMP at a mass ratio of 90:10. Subsequently, spray-coat the mixed slurry onto the surface of the porous tin metal core. After drying, a first coating layer is formed on the surface of the core, and the thickness of the first coating layer is 3 μm.

[0190] (c)Mix alumina ceramic material, ammonium bicarbonate (pore-forming agent), and PVDF (the third binder) evenly in the solvent NMP at a mass ratio of 80:10:10. Subsequently, spray-coat this slurry onto the surface of the material obtained in step (b). After heat treatment at 120 °C for 6 h, a second coating layer is formed on the surface of the first coating layer. The thickness of the second coating layer is 3 μm, and the porosity is 10%, obtaining a composite material.

[0191] 2. Preparation of the anode-free current collector, including: Mix the above composite material, PVDF (the fourth binder), and conductive carbon black (conductive agent) evenly in the solvent water at a mass ratio of 80:10:10 to prepare a coating slurry. Subsequently, coat the coating slurry onto a conventional copper foil substrate by coating. The thickness of the coating is 5 μm, obtaining an anode-free current collector.

[0192] 3. Preparation of the battery, including: Preparation of the positive electrode sheet: Mix the positive electrode active material NCM811, conductive agent conductive carbon black (SP), carbon nanotubes, and binder polyvinylidene fluoride (PVDF5130) in a mass ratio of 97:1.5:0.5:1. Subsequently, add N-methylpyrrolidone (NMP), stir and mix evenly to form a stable positive electrode slurry. Uniformly coat the positive electrode slurry on an aluminum foil with a thickness of 13 μm for the positive electrode current collector, and the coating surface density is 195 g / m 2 , and then after drying, cold pressing, and slitting, a positive electrode sheet is obtained. Select a compaction density of 3.4 g / cm 3 .

[0193] Separator: A polypropylene film with a thickness of 9 μm is selected as the base film of the separator. The separator also includes a ceramic coating with a thickness of 3 μm on one side (ceramic coatings are provided on both sides).

[0194] Electrolyte: In a glove box filled with inert gas, ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate are mixed in a mass ratio of 1:1:1 to obtain an organic solvent. Then, the lithium salt LiPF6 is dissolved in the organic solvent, and the concentration of the lithium salt is 1.2 mol / L to obtain the electrolyte.

[0195] Battery assembly: The positive electrode sheet, separator, and non-negative current collector are arranged in sequence, and the assembly method is winding. The electrolyte is injected into the dry battery cell, and after soaking for 24 h, formation is carried out at 45 °C. The formation process: Charge at 0.05C to 3.4V, and then charge at 0.2C to 3.75V; Aging at room temperature for 24 hours to complete the battery production.

[0196] Example 2 The composite material of Example 2 is prepared according to the preparation method of Example 1 above, with the only difference being that: In step (b), the thickness of the first coating layer is 5 μm.

[0197] Example 3 The composite material of Example 3 is prepared according to the preparation method of Example 1 above, with the only difference being that: In step (b), the thickness of the first coating layer is 2 μm.

[0198] Example 4 The composite material of Example 4 is prepared according to the preparation method of Example 1 above, with the only difference being that: In step (a), the particle size of the porous polyethylene particles is 1000 nm.

[0199] Example 5 The composite material of Example 5 is prepared according to the preparation method of Example 1 above, with the only difference being that: In step (a), the particle size of the porous polyethylene particles is 500 nm.

[0200] Example 6 The composite material of Example 6 is prepared according to the preparation method of Example 1 above, with the only difference being that: In step (c), the porosity of the second coating layer is adjusted to about 20% by controlling the mass ratio of alumina ceramic, ammonium bicarbonate, and binder.

[0201] Example 7 The composite material of Example 7 is prepared according to the preparation method of Example 1 above, with the only difference being that: In step (c), the porosity of the second coating layer is adjusted to be about 5% by controlling the mass ratio of alumina ceramic, ammonium bicarbonate, and binder.

[0202] Example 8 The composite material of Example 8 was prepared according to the preparation method of Example 1 above, with the only difference being that: In step (c), the thickness of the second coating layer is 5 μm.

[0203] Example 9 The composite material of Example 9 was prepared according to the preparation method of Example 1 above, with the only difference being that: In step (c), the thickness of the second coating layer is 2 μm.

[0204] Example 10 The composite material of Example 10 was prepared according to the preparation method of Example 1 above, with the only difference being that: In step (a), the metal material is copper.

[0205] In step (b), the conductive polymer is conductive polyaniline.

[0206] In step (c), the ceramic material is zirconia.

[0207] Example 11 The composite material of Example 11 was prepared according to the preparation method of Example 1 above, with the only difference being that: In step (a), the metal material is zinc.

[0208] In step (b), the conductive polymer is conductive polypyrrole.

[0209] In step (c), the ceramic material is aluminum nitride.

[0210] Example 12 The composite material of Example 12 was prepared according to the preparation method of Example 1 above, with the only difference being that: In step (b), the thickness of the first coating layer is 1 μm.

[0211] Example 13 The composite material of Example 13 was prepared according to the preparation method of Example 1 above, with the only difference being that: In step (c), the thickness of the second coating layer is 8 μm.

[0212] Example 14 The composite material of Example 14 was prepared according to the preparation method of Example 1 above, with the only difference being that: In step (c), the porosity of the second coating layer is 40%.

[0213] Example 15 The composite material of Example 15 was prepared according to the preparation method of Example 1 above, with the only difference being that: In step (a), the particle sizes of polyethylene (template agent) and ammonium bicarbonate (pore-forming agent) were too large, being 1000 nm here; The porosity of the obtained inner core was 68%.

[0214] Comparative Example 1 The composite material of Comparative Example 1 was prepared according to the preparation method of Example 1 above, with the only difference being that: In step (a), the modification treatment of the metal was omitted, that is, the porous feature was not set, and tin metal was directly used as the inner core, and a tin-based inner core without porous characteristics, that is, without a framework structure, was prepared.

[0215] Comparative Example 2 The composite material of Comparative Example 2 was prepared according to the preparation method of Example 1 above, with the only difference being that: Step (b) was omitted, that is, the first coating layer was not set.

[0216] Comparative Example 3 The composite material of Comparative Example 3 was prepared according to the preparation method of Example 1 above, with the only difference being that: Step (c) was omitted, that is, the second coating layer was not set.

[0217] Performance test 1. Performance tests were carried out on the composite materials and non-negative electrode current collectors prepared in the above examples and comparative examples, including: (1) Specific surface area: The specific surface area was measured by the N2 adsorption method, and the specific surface area contained in the composite material was characterized by the adsorption amount of gas.

[0218] (2) Maximum compaction density: The above non-negative electrode current collector was successively passed through a roller press under different pressure conditions. Under the compaction densities of 3.2 T, 3.3 T, 3.4 T, 3.5 T, and 3.6 T, SEM and CP of the cross-section were used to judge whether the composite material in the coating was broken, and the maximum compaction density was recorded.

[0219] (3) Conductivity: The measurement of conductivity was the resistivity test at the powder level. A certain amount of the composite material was loaded into the test container, and the same mass of the composite material was pressed into a dense block under a certain pressure condition such as 3 - 10 tons of pressure, and its resistivity was measured in this state.

[0220] The test results are shown in Table 1 below.

[0221] Table 1 It can be seen from the above relevant physical and chemical property tests of Table 1 that generally speaking, compared with Comparative Examples 1-3, the composite materials and the anode-free current collectors provided by Examples 1-15 of the present invention have a larger specific surface area, a more suitable maximum compaction density, and higher conductivity. The anode-free current collector of the present invention can provide more lithium deposition sites, which is beneficial to improving the uniformity of lithium ion deposition and solving the lithium dendrite problem.

[0222] By comparing Comparative Example 1 with Examples 1-11, it can be seen that the core of Comparative Example 1 was not modified and did not have a porous structure, while the composite materials of Examples 1-11 had a significantly increased specific surface area after being modified by the metal core substrate, and thus could provide more lithium deposition sites. By comparing Example 1 with Examples 12-15, it can be seen that if the second coating layer, that is, the ceramic coating, is too thick, it will significantly reduce the conductivity of the electrode sheet, which hinders the improvement of the power performance. Although the increase in the pores of the ceramic coating can increase the lithium ion transport channels, too many pores will reduce its structural stability, resulting in a low compaction density and hindering the improvement of the energy density of the lithium battery. When the thickness of the first coating layer, that is, the conductive polymer layer, is reduced, although there is no obvious change in the physical and chemical properties, due to the reduction of the conductive polymer, the particles available for physically adsorbing lithium ions are reduced, so it will cause uneven lithium ion adsorption, ultimately affecting the capacity life of the battery. The particle size of the pore former and the template agent is related to the structural strength of the composite material. If it is too large, it will cause larger holes in the composite material and is prone to breakage under pressure, thus affecting the safety performance.

[0223] In addition, it can be seen from Examples 10-11 that changing the type of the metal base and the types of substances of the coating layer has little impact on the final physical and chemical properties, and they all have relatively similar properties. By comparing the examples with Comparative Example 2, it can be seen that Comparative Example 2 did not set the first coating layer, that is, Comparative Example 2 cancelled the conductive polymer layer, which directly reduced the conductivity of the overall composite particles, affecting the power performance of the battery, and the cancellation of the conductive polymer would also affect the deposition stability of lithium ions. By comparing the examples with Comparative Example 3, it can be seen that Comparative Example 3 did not set the second coating layer, that is, Comparative Example 3 cancelled the outer alumina ceramic coating. Although there is no obvious difference in the physical and chemical properties at the material end, this coating plays a role in protecting the lithium ion deposition and avoiding the risk of lithium ion dendrite overflow, so it may affect the safety performance of the battery.

[0224] 2. Perform performance tests on the batteries prepared from the above-mentioned various examples and comparative examples, including: (1)Internal resistance test (DC internal resistance ACR test): Charge and discharge the battery according to the standard charge-discharge regime of 0.5C / 1C. Charge the battery cell at a constant current of 0.5C with constant voltage until 4.25V, let it stand for 30 minutes, then discharge it at a constant current of 1C for 30 minutes, and let it stand for 60 minutes. Use a DC internal resistance tester to measure the DC internal resistance of the battery.

[0225] (2)Capacity retention rate test (capacity retention rate after 500 cycles at 1C): Conduct charge-discharge tests according to the standard test process with a regime of 0.5C / 1C. Charge the battery cell at a constant current of 0.5C with constant voltage until 4.25V, let it stand for 30 minutes, then discharge it at a constant current of 1C until 2.5V, and let it stand for 30 minutes. Conduct cycle tests in sequence until the discharge capacity of the battery is lower than 80% of the initial capacity, then stop the test.

[0226] (3)1C energy density test: 1C energy density = 1C discharge capacity * average 1C discharge voltage / total weight of the battery.

[0227] (4)5C rate capacity retention rate test: Charge the battery cell at a constant current of 0.5C with constant voltage until 4.25V, let it stand for 30 minutes, then discharge it at a constant current of 1C until 2.5V, and let it stand for 30 minutes; charge it again at a constant current of 0.5C with constant voltage until 4.25V, let it stand for 30 minutes, then discharge it at a constant current of 5C until 2.5V. Then the 5C capacity retention rate = 5C discharge capacity / 1C discharge capacity.

[0228] (5)Maximum charge rate test: Repeatedly conduct charge-discharge tests on the battery at rates of 1C, 2C, 3C... according to the standard test process with a regime of 0.5C / XC. Charge the battery cell at a constant current of 0.5C with constant voltage until 4.25V, let it stand for 30 minutes, then discharge it at a constant current of XC until 2.5V, and let it stand for 30 minutes until the battery undergoes thermal runaway. At this time, the rate is the maximum safe rate of the battery without a negative electrode current collector, indirectly reflecting the safety performance of the structure without a negative electrode current collector.

[0229] The test results are shown in Table 2 below.

[0230] Table 2 As can be seen from the data in Table 2 above, Examples 1-11 are within the appropriate range of the present invention, and the comprehensive electrochemical performance shows good performance. Compared with Example 1, in Comparative Example 1, the metal substrate is not porous. Although the compaction density of the composite material can be improved, due to the lack of porous setting, the specific surface area of the composite material is reduced, and the effective lithium-ion deposition area is reduced. Therefore, the uneven deposition of lithium ions and the growth of lithium dendrites will occur, resulting in poor high-rate performance and safety performance. In addition, compared with Example 1, in Examples 12-15, due to the reduction of the thickness of the conductive polymer layer, the polymer addition amount is small, and the ability to physically adsorb lithium ions is reduced. Therefore, the uneven deposition of lithium ions will also occur, affecting performance such as safety. The increase in the thickness of the second coating layer, that is, the ceramic coating, significantly deteriorates the internal resistance of the battery, resulting in poor cycle stability. In addition, due to the increase in thickness, the quality is improved, resulting in a decrease in energy density. And due to the deterioration of the polarization phenomenon, the high-rate performance and safety of the battery are also deteriorated. Compared with Example 1, Examples 14 and 15 are equivalent to more pores and larger holes, and the final result will cause the compressive strength of the composite material to decrease, resulting in particle breakage, affecting the uniform deposition of lithium ions, deteriorating the high-rate and safety performance of the battery, and due to the particle breakage, it will also affect the battery capacity, resulting in a decrease in energy density and deterioration of cycle performance.

[0231] In addition, for Examples 10 and 11, the fine-tuning of the metal matrix has basically the same effect on the battery performance, with little difference. In Comparative Example 2, since the first coating layer, that is, the conductive polymer layer, is removed, on the one hand, due to the reduction of conductivity, the polarization of the battery is increased, so the cycle performance and rate retention rate are both affected. And the conductive polymer layer also has the function of promoting lithium-ion deposition. Therefore, the maximum charging rate of this group is reduced, that is, the safety performance is decreased. In Comparative Example 3, since the second coating layer, that is, the ceramic coating, is removed, the function of the protective layer is lost. Therefore, the cycle performance and charging ability of the battery are reduced due to easy lithium deposition, and the comprehensive performance of the battery is decreased.

[0232] The parts not described in detail in the present invention are well-known technologies to those skilled in the art.

[0233] The basic principles of the present invention have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, advantages, effects, etc. mentioned in the present invention are only examples and not limitations. It cannot be considered that these advantages, advantages, effects, etc. are essential for each embodiment of the present invention. In addition, the above-disclosed specific details are only for the purpose of illustration and easy understanding, and are not limitations. The above details do not limit the present invention to necessarily adopt the above specific details to implement.

[0234] It should be noted that the term "and / or" or " / " used in this text is merely a description of the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The singular forms "a", "the", and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0235] In the specific embodiments and the claims, a list of items connected by the terms "at least one of", "at least one in", "at least one kind in", or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A, B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0236] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite material, characterized in that, The composite material includes: a core, the core includes a metal, and the core has a framework structure; a first coating layer, the first coating layer coats at least part of the surface of the core, and the first coating layer includes a conductive polymer; and a second coating layer, the second coating layer coats at least part of the surface of the first coating layer, and the second coating layer includes a ceramic material.

2. The composite material according to claim 1, characterized in that, The core, the first coating layer, and the second coating layer satisfy at least one of the following features (1) to (13): (1) The metal includes at least one of transition metals or post-transition metals; (2) The core further includes a first binder; (3) The pore diameter of the pores in the framework structure ranges from 100 nm to 500 nm; (4) The porosity of the core is 20% to 50%; (5) The average particle size of the core ranges from 2 μm to 5 μm; (6) The conductive polymer includes at least one of conductive polyimide, conductive polyaniline, or conductive polypyrrole; (7) The first coating layer further includes a second binder; (8) The average particle size of the conductive polymer ranges from 100 nm to 500 nm; (9) The thickness of the first coating layer is 2 μm to 5 μm; (10) The ceramic material includes at least one of alumina, zirconia, aluminum nitride, silicon nitride, magnesium oxide, tin oxide, or titanium oxide; (11) The second coating layer further includes a third binder; (12) The second coating layer has a porous structure; (13) The thickness of the second coating layer is 2 μm to 5 μm.

3. The composite material according to claim 2, wherein The core satisfies at least one of the following features (1) to (3): (1) The metal includes at least one of copper, tin, silver, or zinc; (2) The mass ratio of the metal to the first binder is (95 to 98):(2 to 5); (3) The first binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide, or polyamide.

4. The composite material according to claim 2, characterized in that, The first coating layer and the second coating layer satisfy at least one of the following features (1) to (5): (1) The mass ratio of the conductive polymer to the second binder is (80 to 90):(10 to 20); (2) The second binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide, or polyamide; (3) The mass ratio of the ceramic material to the third binder is (80 to 90):(10 to 20); (4) The third binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide, or polyamide; (5) The porosity of the second coating layer is 5% to 20%.

5. A method for preparing a composite material, characterized in that, Including the following steps: Mix a porous template agent with a metal compound solution, add a reducing agent, and then perform a first drying to obtain a core with a framework structure; Coat a slurry containing a conductive polymer on the surface of the core to form a first coating layer on at least part of the surface of the core; Coat a slurry containing a ceramic material on the surface of the first coating layer to form a second coating layer on at least part of the surface of the first coating layer.

6. The preparation method of the composite material according to claim 5, characterized in that, The preparation method satisfies at least one of the following features (1) to (8): (1) The preparation of the porous template agent includes: Grind a template agent and a pore-forming agent to obtain particles with an average particle size of 100 nm to 500 nm; Mix the particles evenly with a first binder and a first solvent to obtain a slurry; Coat the slurry on a substrate to form a thin film, and after a second drying and a pulverization treatment, obtain the porous template agent; (2) The mixing of the porous template agent with the metal compound solution includes: Immerse the porous template agent in the metal compound solution for 2 h to 4 h; (3) The reducing agent includes at least one of iron, zinc, or hydrazine hydrate; (4) After the first drying, it further includes: Immerse the metal-deposited porous template agent after the first drying in a benzene solvent for 4 h to 12 h, then perform washing and a third drying to obtain the core with a framework structure; (5) The slurry containing a conductive polymer contains a conductive polymer, a second binder, and a second solvent; (6) After coating the slurry containing a conductive polymer on the surface of the core, perform a fourth drying, and the temperature of the fourth drying is 60°C to 100°C; (7) The slurry containing a ceramic contains a ceramic material, a third binder, and a third solvent; (8) After coating the slurry containing a ceramic material on the surface of the first coating layer, perform a heat treatment, and the temperature of the heat treatment is 100°C to 150°C and the time is 4 h to 8 h.

7. The method for preparing the composite material according to claim 6, characterized in that, The preparation method satisfies at least one of the following features (1) to (16): (1) The average particle size range of the porous template agent is 500 nm to 1000 nm; (2) The template agent includes at least one of polyethylene, polyethylene glycol, polyvinylpyrrolidone, or cetyltrimethylammonium bromide; (3) The pore-forming agent includes at least one of ammonium bicarbonate, ammonium carbonate, ammonium nitrate, or ammonium sulfate; (4) The mass ratio of the first binder, the template agent, and the pore-forming agent is (60 - 80):(10 - 20):(10 - 20); (5) The first solvent includes at least one of N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide, or water; (6) The temperature of the second drying is 60°C to 100°C; (7) The metal ions in the metal compound solution include at least one of copper ions, tin ions, silver ions, or zinc ions; (8) The anions in the metal compound solution include at least one of nitrate, sulfate, chloride, or acetate; (9) The temperature of the first drying is 60°C to 100°C; The temperature of the third drying is 60°C to 100°C; The mass ratio of the conductive polymer to the second binder is (80 to 90):(10 to 20); The second solvent includes at least one of N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide, or water; The average particle size range of the conductive polymer is 100 nm to 500 nm; The slurry containing ceramics further includes a pore-forming agent; The mass ratio of the ceramic material, the pore-forming agent, and the third binder is (70 to 80):(10 to 20):(10 to 20); The third solvent includes at least one of N-methylpyrrolidone, dimethyl sulfoxide, dimethylformamide, or water.

8. A current collector without a negative electrode, characterized in that, The non-anode current collector includes a substrate and a coating provided on at least one surface of the substrate, and the coating includes the composite material according to any one of claims 1 to 4, and / or includes the composite material prepared by the preparation method according to any one of claims 5 to 7.

9. The current collector without a negative electrode according to claim 8, characterized in that, The coating further includes a fourth binder and a conductive agent; The fourth binder includes at least one of polyvinylidene fluoride, polytetrafluoroethylene, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylonitrile, polyvinyl alcohol, polyacrylate, polyacrylic acid, polyacrylamide, polyimide, or polyamide; the conductive agent includes at least one of conductive carbon black, conductive graphite, carbon nanotubes, carbon fibers, or graphene; The mass ratio of the composite material, the fourth binder, and the conductive agent is (70 to 80):(10 to 20):(10 to 20); and / or, the substrate includes a copper-based substrate or a composite substrate, and the composite substrate includes a substrate formed by the composite of a polymer material and a metal; and / or, the thickness of the coating is 2 μm to 10 μm.

10. A battery, characterized in that, The battery includes the composite material according to any one of claims 1 to 4, or includes the composite material prepared by the preparation method according to any one of claims 5 to 7, or includes the non-anode current collector according to claim 8 or 9.

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