Current collector and preparation method thereof, battery, battery pack, battery pack and electric equipment

Abstract

The invention discloses a current collector and a preparation method thereof, a battery, a battery pack, a battery pack and electric equipment. The current collector comprises a current collector body and a buffer layer. The buffer layer is arranged on the surface of the current collector body, and the buffer layer comprises a conductive substance which reacts with hydrogen sulfide. According to the current collector disclosed by the invention, the current collector body is coated with the buffer layer, and the conductive substance in the buffer layer can react with hydrogen sulfide, so that the conductivity of the current collector is ensured, and H2S gas generated in a long-term cycle process of a battery can be isolated through the buffer layer; therefore, the condition of premature failure of the battery caused by corrosion of the current collector by H2S gas is avoided, and the service life of the battery is prolonged.

Description

Current collectors and their preparation methods, batteries, battery packs, battery bags and electrical equipment Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a current collector and its preparation method, a battery, a battery pack, a battery module, and electrical equipment. Background Technology

[0002] All-solid-state batteries replace the electrolyte and separator components in liquid batteries with inorganic solid electrolytes, improving the safety performance of lithium-ion batteries. Among solid electrolytes, sulfide electrolytes possess ionic conductivity comparable to electrolytes and good processing performance, thus sulfide all-solid-state batteries are widely considered by academia and industry to be the most promising next-generation battery. However, sulfide electrolytes are highly sensitive to water, readily reacting to generate highly toxic acidic hydrogen sulfide (H2S) gas. H2S gas can react with the negative electrode current collector (e.g., copper foil) (generating Cu2S), corroding the negative electrode current collector and leading to decreased conductivity and contact failure between the current collector and the negative electrode material. Related technologies often reduce the contact between sulfide electrolytes and water in the air through process dew point control and sealing, but it is still impossible to completely prevent trace amounts of water from reacting with the electrolyte to generate H2S gas during long-term battery operation cycles. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a current collector that facilitates the isolation of H2S gas generated by the battery during long-term cycling through a buffer layer, thereby avoiding premature battery failure caused by corrosion of the current collector by H2S gas, and extending the battery's service life.

[0004] According to a first aspect of the present invention, a current collector includes: a current collector body; and a buffer layer disposed on the surface of the current collector body, the buffer layer comprising a conductive material that reacts with hydrogen sulfide.

[0005] According to an embodiment of the present invention, a buffer layer is coated on the outside of the current collector body. The conductive material in the buffer layer can react with hydrogen sulfide. While ensuring the conductivity of the current collector, the buffer layer helps to isolate the H2S gas generated by the battery during long-term cycling, thereby avoiding premature battery failure caused by corrosion of the current collector by H2S gas and extending the battery's service life.

[0006] According to some embodiments of the present invention, the pH of the buffer layer is 8 to 12.

[0007] According to some embodiments of the present invention, the pH of the buffer layer is 9 to 11.

[0008] According to some embodiments of the present invention, the conductive material is a base-containing conductive polymer.

[0009] According to some embodiments of the present invention, the conductive material is at least one selected from polyacetylene, polypyrrole, polythiophene, polyphenylene, polyphenylacetylene, and polyaniline.

[0010] According to some embodiments of the present invention, the molecular weight of the conductive polymer is 50,000 to 1,000,000; and / or the conductivity of the conductive polymer is 0.5 × 10⁻⁶. 2 S / cm~10×10 2 S / cm.

[0011] According to some embodiments of the present invention, the thickness of the buffer layer is 0.5 μm to 10 μm.

[0012] The method for preparing a current collector according to a second aspect of the present invention includes the following steps: forming a buffer layer by disposing a mixture containing a conductive substance that reacts with hydrogen sulfide on the current collector body.

[0013] According to some embodiments of the present invention, the mixture is a liquid mixture, and the solid content of the liquid mixture is 5% to 20%.

[0014] According to some embodiments of the present invention, the pH of the mixture is adjusted to 8 to 12.

[0015] According to some embodiments of the present invention, at least one conductive substance selected from polyacetylene, polypyrrole, polythiophene, polyphenylene, polyphenylacetylene, and polyaniline is dissolved to obtain the liquid mixture.

[0016] According to some embodiments of the present invention, the liquid mixture is coated onto the current collector body.

[0017] According to some embodiments of the present invention, the liquid mixture is coated by a coating method, a pouring method, a liquid immersion method, or a spin coating method.

[0018] A battery according to a third aspect of the present invention includes a negative electrode sheet, the negative electrode sheet including a negative electrode current collector, the negative electrode current collector being a current collector according to the first aspect of the present invention described above, or a current collector prepared by a method including the current collector according to the second aspect of the present invention described above; and a negative electrode layer including a negative electrode active material, the negative electrode active material including at least one selected from pure silicon, silicon-carbon, graphite and silicon oxide.

[0019] According to some embodiments of the present invention, the negative electrode layer further includes 5w% to 60w% electrolyte, based on the weight of the negative electrode layer.

[0020] According to some embodiments of the present invention, the battery further includes a positive electrode sheet, the positive electrode sheet comprising a positive electrode layer, the positive electrode layer comprising a positive electrode active material and a solid electrolyte, wherein the solid electrolyte comprises a glassy or glass-ceramic Li-PS system, a sulfur-silver-germanium Li6PS5X system, or a lithium-germanium-phosphorus-sulfur Li-PS system. 10 GeP2S 12 At least one of the systems.

[0021] According to some embodiments of the present invention, the positive electrode active material includes at least one of olivine-based materials, layered oxide-based materials, and spinel-based materials.

[0022] According to some embodiments of the present invention, the content of the positive electrode active material is 50w% to 85w, and the content of the solid electrolyte is 5w% to 50w, based on the weight of the positive electrode layer.

[0023] According to some embodiments of the present invention, the positive electrode layer further includes a binder and a conductive agent, wherein the content of the binder is 0.1w% to 10w and the content of the conductive agent is 0.1w% to 10w, based on the weight of the positive electrode layer.

[0024] A battery pack according to a fourth aspect of the present invention includes at least one battery according to the third aspect of the present invention described above.

[0025] A battery pack according to a fifth aspect of the present invention includes at least one battery according to the third aspect of the present invention, or includes at least one battery pack according to the fourth aspect of the present invention.

[0026] An electrical appliance according to a sixth aspect of the present invention includes at least one battery according to the third aspect of the present invention, or includes at least one battery pack according to the fourth aspect of the present invention, or includes at least one battery pack according to the fifth aspect of the present invention.

[0027] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Detailed Implementation

[0028] The following describes a current collector according to a first aspect embodiment of the present invention, comprising a current collector body and a buffer layer. The buffer layer is disposed on the surface of the current collector body and comprises a conductive material that reacts with hydrogen sulfide. By covering the surface of the current collector body with the buffer layer, on the one hand, the conductive material in the buffer layer is conductive, preventing the current collector from becoming an insulator due to the buffer layer, thus ensuring the normal use of the current collector; on the other hand, the buffer layer provides good protection, isolating the H2S gas generated during long-term battery cycling, thereby preventing premature battery failure due to corrosion of the current collector by H2S gas, and extending the battery's lifespan.

[0029] According to an embodiment of the present invention, a buffer layer is provided outside the current collector body. The conductive material in the buffer layer can react with hydrogen sulfide. While ensuring the conductivity of the current collector, it is beneficial to isolate the H2S gas generated by the battery during long-term cycling through the buffer layer, thereby avoiding premature battery failure caused by corrosion of the current collector by H2S gas, and extending the battery's service life.

[0030] According to some embodiments of the present invention, the pH of the buffer layer is 8–12. When the pH of the buffer layer is less than 8, the alkalinity of the buffer layer is weak, resulting in poor adsorption of acidic H2S gas generated in the battery. When the pH of the buffer layer is greater than 12, the alkalinity of the buffer layer is strong, causing the conductive material in the buffer layer to easily react with H2S to directly generate H2O. The generated H2O will then react with the sulfide electrolyte in the battery to release H2S gas, easily leading to a decline in battery performance. Therefore, by controlling the pH of the buffer layer to 8–12, the H2S gas generated during battery cycling is fully absorbed, thereby improving battery performance.

[0031] Preferably, the pH of the buffer layer is 9 to 11.

[0032] Furthermore, the conductive material is a base-containing conductive polymer. Base-containing conductive polymers are polymers containing basic functional groups (such as amine groups) in their structure. Due to the presence of these basic groups, these polymers can react with acidic gases (such as sulfur dioxide). For example, amine-containing polymers can combine with protons (H+) in acidic gases through the amine group to form salts or other types of compounds. The basicity of the conductive polymer is adjusted by the base groups, which can be one or more of amino (R-NH2) or amine (R1-NH-R2) groups. These base groups can be introduced into the conductive polymer chain segments through copolymerization or side branching to adjust the pH value. The base groups can adsorb acidic H2S gas, reducing its diffusion to the surface of the current collector and improving the battery's cycle life.

[0033] Furthermore, the conductive material is at least one selected from polyacetylene, polypyrrole, polythiophene, polyphenylene, polyphenylacetylene, and polyaniline. Among these, polyacetylene... Polypyrrole Polythiophene Polyphenylene Polyphenylene acetylene Polyaniline The polymer exhibits high strength, good toughness, and stable chemical properties. Therefore, using at least one of the aforementioned polymers can improve the stability of the buffer layer on the surface of the current collector and extend its service life.

[0034] The above-mentioned polymers are synthesized using methods such as ionic liquid polymerization and electrochemical polymerization. Specifically, taking the synthesis of polyaniline as an example, firstly, aniline monomers undergo a polymerization reaction to polymerize aniline into polyaniline. During this process, an appropriate catalyst is used, and the pH of the solution is adjusted using concentrated hydrochloric acid and ammonium sulfate. The reaction is carried out at room temperature, and the molecular weight and properties of polyaniline are adjusted by controlling the reaction conditions. The resulting polyaniline polymer can be obtained by side-branch copolymerization of segments containing base groups (R-NH2, R1-NH-R2).

[0035] Furthermore, the molecular weight of the conductive polymer is between 50,000 and 1,000,000. Conductive polymers meeting these molecular weights exhibit better electrical conductivity, and their chain segments can provide more electron transport paths, thereby increasing the effective mobility of charge carriers. Simultaneously, conductive polymers meeting these molecular weights also possess better mechanical strength and toughness, with stronger interactions between chain segments, allowing them to withstand greater stress without fracture.

[0036] The conductivity of the conductive polymer is 0.5 × 10⁻⁶. 2 S / cm~10×10 2 S / cm. Conductivity refers to the ability of a conductive polymer to conduct current. Conductive polymers that meet the above conductivity requirements are beneficial for improving the charge / discharge rate, cycle stability, and overall efficiency of batteries using current collectors with conductive polymers.

[0037] The method for detecting the pH of the buffer layer is as follows: dissolve the buffer layer in acetone solvent to prepare a polymer solution with a mass fraction of 5% (the polymer comes from the buffer layer), take a drop of the polymer solution and drop it on a standard pH test paper, let it stand for 5 minutes, and compare it with the standard colorimetric card.

[0038] According to some embodiments of the present invention, the thickness of the buffer layer is 0.5 μm to 10 μm. Therefore, by setting the thickness of the buffer layer to 0.5 μm to 10 μm, it is easy to achieve a uniform distribution of the buffer layer on the surface of the current collector body while ensuring the energy density of the battery, thereby achieving better resistance to H2S corrosion.

[0039] The thickness of the buffer layer can be 0.6 μm, 1 μm, 6 μm, 8 μm, or 9.6 μm, but is not limited to these. Preferably, the thickness of the buffer layer is 1 μm to 8 μm.

[0040] A method for preparing a current collector according to a second aspect of the present invention includes the following steps: forming a buffer layer by disposing a mixture containing a conductive substance that reacts with hydrogen sulfide on the current collector body.

[0041] According to the method for preparing the current collector according to the embodiments of the present invention, the operation of setting a buffer layer on the current collector body is relatively simple, which is beneficial to improving the preparation efficiency of the current collector.

[0042] Furthermore, the mixture is a liquid mixture with a solid content of 5% to 20%. Liquid mixtures that meet the above solid content have good fluidity and stability, ensuring that the stability and quality of the buffer layer formed on the surface of the current collector meet the requirements of the current collector.

[0043] According to some embodiments of the present invention, the pH of the mixture is adjusted to 8-12. Thus, the pH of the buffer layer on the surface of the current collector body meets the requirements of the current collector.

[0044] Further, at least one conductive substance selected from polyacetylene, polypyrrole, polythiophene, polyphenylene, polyphenylacetylene, and polyaniline is dissolved to obtain a liquid mixture. The conductive substance can be dissolved in an oily solvent, such as xylene, toluene, or acetone, but is not limited thereto. This results in a liquid mixture with better homogeneity, which is beneficial for improving the quality of the formed buffer layer.

[0045] According to some embodiments of the present invention, the liquid mixture is coated onto the current collector body. This coating method helps to increase the uniformity of the liquid mixture on the current collector body, thereby improving the quality of the formed buffer layer.

[0046] Furthermore, the liquid mixture can be coated using methods such as coating, casting, immersion, or spin coating. Coating involves applying the liquid mixture onto the current collector body, then curing the coating through solvent evaporation, cooling, or chemical cross-linking to form a buffer layer. The thickness of the buffer layer formed by the liquid mixture coating can be controlled by adjusting the viscosity of the liquid mixture, the coating speed, or the gap of the coating tool. Casting involves extruding the liquid mixture through a die using an extruder, casting it in sheet form onto a smoothly rotating roller. The sheet is shaped on the roller, then pulled, trimmed, and wound up. Immersion involves immersing the current collector body into the liquid mixture to promote the formation of the buffer layer on the current collector body. Spin coating involves rotating the current collector body at high speed, causing the liquid mixture to be evenly distributed on the surface of the current collector body under centrifugal force and ultimately cured into a buffer layer.

[0047] A battery according to a third aspect embodiment of the present invention includes a negative electrode sheet, which includes a negative electrode current collector and a negative electrode layer. The negative electrode current collector is a current collector according to the first aspect embodiment of the present invention described above, or a current collector prepared by a method according to the second aspect embodiment of the present invention described above. The negative electrode layer includes a negative electrode active material, which includes at least one of pure silicon, silicon-carbon, graphite, and silicon oxide. The negative electrode layer can be coated onto the current collector body by wet coating or dry extrusion to simplify the process of setting the negative electrode layer on the negative electrode current collector and improve the preparation efficiency of the negative electrode sheet. Pure silicon, silicon-carbon, graphite, and silicon oxide all have high specific capacity and good conductivity, which are beneficial to improving the charge-discharge performance of the battery and enhancing the overall performance of the battery.

[0048] The battery according to the embodiments of the present invention has good charge and discharge performance and a long service life, which is conducive to improving the market competitiveness of the battery.

[0049] Furthermore, based on the weight of the negative electrode layer, the negative electrode layer also includes 5w% to 60w% of electrolyte. When the electrolyte content is less than 5w%, there are fewer freely moving ions provided by electrolyte ionization, which easily reduces the conductivity of the negative electrode sheet; when the electrolyte content is greater than 60w%, the electrolyte content is too high, which easily increases the cost of the battery. Therefore, by using 5w% to 60w% of electrolyte, it is beneficial to improve the battery's conductivity and cycle performance, while also helping to control the battery's cost.

[0050] According to some embodiments of the present invention, the battery further includes a positive electrode sheet, which includes a positive electrode layer. The positive electrode layer includes a positive electrode active material and a solid electrolyte, wherein the solid electrolyte includes a Li-PS (lithium-phosphorus-sulfur) system, a sulfur-silver-germanium Li6PS5X system, or a lithium-germanium-phosphorus-sulfur Li... 10 GeP2S 12 At least one of the following in the system. The positive electrode active material is capable of storing electrical energy through a chemical reaction and releasing it through the opposite chemical reaction when needed. During charging, the positive electrode active material absorbs electrical energy and undergoes a redox reaction, while during discharging, it releases electrical energy and undergoes the opposite redox reaction. Solid electrolytes are advantageous in providing ion conductors, thereby facilitating charge transfer.

[0051] Li-PS systems can exist in either a glassy or glass-ceramic state. Glass-ceramic Li-PS systems are solid electrolytes composed of lithium, phosphorus, and sulfur, exhibiting high ionic conductivity (approaching that of liquid electrolytes), good chemical stability, and low cost. The silver-sulfur germanium (Li6PS5X, X = Cl, Br, I) system is a solid electrolyte containing lithium, phosphorus, sulfur, and halogen elements (such as chlorine, bromine, or iodine). The silver-sulfur germanium Li6PS5X system exhibits high ionic conductivity, especially when X is chlorine, displaying a conductivity as high as 10⁻⁶. -3 The room-temperature ionic conductivity is S / cm. Simultaneously, the sulfur-silver-germanium Li6PS5X system also exhibits good mechanical properties and chemical stability. Lithium-germanium-phosphorus-sulfur (Li... 10 GeP2S 12 The system is a solid electrolyte with lithium, germanium, phosphorus, and sulfur as its main components. It has extremely high lithium-ion conductivity (approximately 10⁻⁶) at room temperature. -3 With a strength of S / cm and high mechanical strength, it can effectively prevent the formation of lithium dendrites. Furthermore, glassy or glass-ceramic Li-PS systems, silver-sulfur-germanium Li6PS5X systems, and lithium-germanium-phosphorus-sulfur Li... 10 GeP2S 12 The systems all have unique crystal structures that can promote rapid ion transport, and at the same time have good interfacial stability with the positive electrode active material, which helps to improve the overall performance and cycle life of the battery.

[0052] Furthermore, the positive electrode active material includes at least one of olivine-based materials, layered oxide-based materials, and spinel-based materials. Olivine-based materials exhibit high thermal stability, are not prone to decomposition and gas generation, and demonstrate good safety under overcharge or high-temperature conditions. They also exhibit good cycle stability, maintaining their structural stability even after multiple charge-discharge cycles. Layered oxide-based materials provide high energy density and relatively stable electrochemical performance. Spinel-based materials facilitate rapid ion migration, thereby improving the battery's charge-discharge rate.

[0053] According to some embodiments of the present invention, the positive electrode active material includes LiFePO4; NCM, NCA, LiCoO2; LiMn2O4, Li4Ti5O 12At least one of the following. NCM refers to a mixed oxide of nickel (Ni), manganese (Mn), and cobalt (Co), with common combinations including but not limited to NCM111 (1:1:1 ratio), NCM523 (5:2:3 ratio), and NCM811 (8:1:1 ratio). NCM can provide higher energy density because the higher the nickel content, the higher the voltage plateau of the material, thus improving the energy density of the battery. NCA is mainly composed of nickel (Ni), cobalt (Co), and aluminum (Al). The addition of aluminum helps to improve the structural stability of the material and improve cycle life. The above-mentioned olivine-based materials (LiFePO4), layered oxide materials (NCM, NCA, LiCoO2), and spinel-based materials (LiMn2O4, Li4Ti5O4) are used. 12 At least one of the following can help improve the electrochemical performance of the battery, enhance the safety of battery use, and reduce the cost of battery.

[0054] According to some specific embodiments of the present invention, the positive electrode sheet further includes a binder, a conductive agent, and a solvent. The binder, by bonding the positive electrode active material, solid electrolyte, and conductive agent together, helps maintain the structural integrity of the positive electrode sheet, enhances its mechanical strength, enables it to withstand stress during battery manufacturing and use, avoids cracking or breakage, and extends its service life. The conductive agent, by forming a continuous conductive network in the positive electrode sheet, greatly improves electron transport efficiency, allowing the battery to operate at higher currents, thereby improving the battery's power density. The addition of the solvent helps increase the mixing uniformity of the positive electrode active material, solid electrolyte, binder, and conductive agent in the positive electrode sheet, thereby improving the consistency of the positive electrode sheet.

[0055] The binder is at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), nitrile rubber (NBR), polyacrylate, polyacrylic acid (PAA), alkyl cellulose, and polyethylene oxide (PEO). All of these binders possess good chemical stability, thermal stability, and mechanical properties. Therefore, using at least one of these binders is beneficial for improving the stability of the positive electrode and extending its service life.

[0056] The conductive agent is at least one of acetylene black, carbon nanotubes, carbon fibers, and carbon black. These conductive agents are low in cost and readily accelerate electron transport efficiency, enabling the battery to maintain stable performance through multiple charge-discharge cycles.

[0057] The solvent is at least one selected from xylene, toluene, trimethylbenzene, anisole, diethyl carbonate, butyl carbonate, methyl ethyl carbonate, butyl acetate, butyl butyrate, and methyl benzoate. The above solvents have good dispersion effects on positive electrode active materials, solid electrolytes, binders, and conductive agents, and are relatively inexpensive, which helps to improve the quality of the positive electrode sheet while controlling its production cost.

[0058] Furthermore, based on the weight of the positive electrode layer, the content of the positive electrode active material is 50w%–85w, and the content of the solid electrolyte is 5w%–50w. This configuration results in a reasonable balance of positive electrode active material and solid electrolyte content in the positive electrode layer, which is beneficial for fully utilizing the functions of these materials, improving the quality of the positive electrode sheet, and thus enhancing its performance. This, in turn, improves the charge-discharge cycle stability of the battery and enhances its overall applicability.

[0059] Furthermore, the positive electrode layer also includes a binder and a conductive agent. Based on the weight of the positive electrode layer, the binder content is 0.1 wt%–10 wt%, and the conductive agent content is 0.1 wt%–10 wt%. The binder helps to firmly bond the positive electrode active material and the conductive agent together, forming a stable electrode structure. It also improves the mechanical strength of the positive electrode layer, preventing cracking or detachment due to volume changes during charging and discharging. The conductive agent improves the electronic conductivity of the positive electrode layer, ensuring uniform current distribution and reducing internal resistance loss. The aforementioned content of binder and conductive agent is reasonable, maximizing their effectiveness and avoiding waste.

[0060] A battery pack according to a fourth aspect of the present invention includes at least one battery according to the third aspect of the present invention described above.

[0061] According to the battery pack of the present invention, the battery pack has stable charging and discharging performance and a long service life, which helps to enhance the market competitiveness of the battery pack.

[0062] A battery pack according to a fifth aspect of the present invention includes at least one battery according to the third aspect of the present invention, or includes at least one battery pack according to the fourth aspect of the present invention.

[0063] The battery pack according to embodiments of the present invention helps to extend the service life of the battery pack, improve the user experience of the battery pack, and thus enhance the market competitiveness of the battery pack.

[0064] An electrical appliance according to a sixth aspect of the present invention includes at least one battery according to the third aspect of the present invention, or includes at least one battery pack according to the fourth aspect of the present invention, or includes at least one battery pack according to the fifth aspect of the present invention.

[0065] According to the embodiments of the present invention, the power supply of the electrical equipment is relatively stable, which is conducive to improving the stability of the use of the electrical equipment and thus improving the user experience.

[0066] The embodiments of the present invention are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known to others. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0067] In Example 1, all the following steps were completed in a drying room with a dew point below -50°C.

[0068] Step 1: Add 75g of NCM811 cathode material, 20g of solid electrolyte Li6PS5Cl, 3g of binder, and 2g of acetylene black to 100g of xylene solvent, and then stir in a vacuum mixer to form a stable and uniform cathode slurry. Intermittently coat this cathode slurry evenly onto both sides of a carbon-coated aluminum foil (160mm width, 16μm thickness), then dry at 373K. After pressing with a roller press, a composite cathode layer is obtained.

[0069] Step 2: Add 58.2g of Li6PS5Cl and 1.8g of binder to 60g of xylene solution and stir thoroughly until a stable and homogeneous positive electrode slurry is formed. Continuously coat the positive electrode slurry onto the composite positive electrode layer, then dry at 373K, controlling the coating thickness to 50μm to obtain the positive electrode sheet.

[0070] Step 3: Cut the electrolyte layer-composite positive electrode layer into a 21mm×41mm membrane.

[0071] Step 4: Place 48g of pure silicon and 2g of binder into 50g of aqueous solution and stir thoroughly until a stable and uniform negative electrode slurry is formed.

[0072] The negative electrode slurry was uniformly and intermittently coated onto the above-mentioned 1 μm thick polyaniline (pH=10, molecular weight 500,000, conductivity 5×10⁻⁶). 2 The negative electrode current collector (S / cm) is applied to both sides of the copper foil current collector, then dried at 373K and then dried in a vacuum oven at 353K for 12 hours. It is then cut into 20mm×40mm films.

[0073] Step 5: Align the positive electrode sheet obtained in Step 3 and the negative electrode sheet obtained in Step 4 and place them in a hot press. Hot press at 453K for 1 hour at a pressure of 200MPa. After vacuum sealing with an aluminum-plastic film, remove the sample. Finally, press the pressed sample in an isostatic press at 200MPa for 300 seconds to obtain the battery of this embodiment.

[0074] Example 2 The difference between Example 2 and Example 1 is that the negative electrode current collector used is a copper foil coated with polyaniline, wherein the pH of the polyaniline is 9, and the rest of the battery assembly steps are consistent with those of Example 1.

[0075] Example 3 differs from Example 1 in that the negative electrode current collector used is a copper foil coated with polyaniline, wherein the pH of the polyaniline is 11, and the rest of the battery assembly steps are consistent with those of Example 1.

[0076] Example 4 differs from Example 1 in that the negative electrode current collector used is a copper foil coated with polyaniline, wherein the pH of the polyaniline is 8, and the rest of the battery assembly steps are consistent with those of Example 1.

[0077] Example 5 differs from Example 1 in that the negative electrode current collector used is a copper foil coated with polyaniline, wherein the pH of the polyaniline is 12, and the rest of the battery assembly steps are consistent with those of Example 1.

[0078] Example 6 differs from Example 1 in that the negative electrode current collector used is a copper foil current collector with a coating thickness of 0.5 μm and a polyaniline (pH=10) coating. The rest of the steps are consistent with the battery assembly steps in Example 1.

[0079] Example 7 differs from Example 1 in that the negative electrode current collector used is a copper foil current collector with a coating thickness of 10 μm and a polyaniline (pH=10) coating. The rest of the steps are consistent with the battery assembly steps in Example 1.

[0080] Example 8 differs from Example 1 in that the negative electrode current collector used is a copper foil coated with polyaniline, but the pH value of the polyaniline is adjusted to 14. The rest of the steps are the same as the battery assembly steps in Example 1.

[0081] Example 9 differs from Example 1 in that the negative electrode current collector used is a copper foil coated with polyaniline, but the pH value of the polyaniline is adjusted to 6. The rest of the steps are the same as the battery assembly steps in Example 1.

[0082] Example 10 differs from Example 1 in that the negative electrode current collector used is a copper foil current collector with a coating thickness of 15 μm and a polyaniline (pH=10) coating. The rest of the steps are consistent with the battery assembly steps in Example 1.

[0083] Example 11 differs from Example 1 in that the negative electrode current collector used is a copper foil current collector with a coating thickness of 0.3 μm and a polyaniline (pH=10) coating. The rest of the steps are consistent with the battery assembly steps in Example 1.

[0084] Example 12 differs from Example 1 in that the molecular weight of the polyaniline used is 50,000, while the rest of the battery assembly steps are consistent with those in Example 1.

[0085] Example 13 differs from Example 1 in that the molecular weight of the polyaniline used is 1 million, while the rest of the battery assembly steps are consistent with those in Example 1.

[0086] Example 14 differs from Example 1 in that the molecular weight of the polyaniline used is 40,000, while the rest of the battery assembly steps are consistent with those in Example 1.

[0087] Example 15 differs from Example 1 in that the molecular weight of the polyaniline used is 1.5 million, while the rest of the battery assembly steps are consistent with those in Example 1.

[0088] The difference between Comparative Example 1 and Example 1 is that the negative electrode current collector used is copper foil coated with SBR (Styrene-Butadiene Rubber). The polymer SBR is not conductive. The rest of the assembly steps are the same as those in Example 1.

[0089] The difference between Comparative Example 2 and Example 1 is that the negative electrode current collector used is a light copper foil, while the rest of the battery assembly steps are the same as those in Example 1.

[0090] For performance testing, five batteries from each of the examples and comparative examples were taken and tested at 0.1C using a LANDCT2001C secondary battery performance testing device at 298±1K. The steps were as follows: rest for 10 minutes; constant current charging to 4.2V cutoff; rest for 10 minutes, then constant current discharging to 2.6V. The capacity of the first discharge cycle is the battery's full capacity. This step was repeated, cycling once more at 0.1C. Cycling performance tests were then conducted on the battery at different rates (0.2C, 0.33C, 0.5C, 1C), and the number of cycles in which the battery capacity decayed to 80% was taken as its cycle life.

[0091] Table 1. Component data for Examples 1-15 and Comparative Examples 1-2: Capacity Performance (mAh / g) First-Cell Performance (0.5C) Specific Capacity (mAh / g) 0.2C Cycle Life (cycles) 0.33C Cycle Life (cycles) 0.5C Cycle Life (cycles) 1C Cycle Life (cycles) Example 1: 205.78 5.80% 190.18 407 807 105 30 Example 2: 203.58 5.10% 184.37 906 605 904 30 Example 3: 203.885.20% 183.2780690610470 Example 4: 203.185.00% 180.2730590550410 Example 5: 205.385.30% 181.2710570530400 Example 6: 205.886.00% 191.1610550490410 Example 7: 204.184.8188.2720610530450 Example 8: 204.885.20% 182.55 30440 370 210 Example 9: 205.485.30% 184.56 605 704 90 310 Example 10: 199.783.40% 173.25 604 703 30 260 Example 11: 204.585.40% 187.35 30410 310 260 Example 12: 205.185.20% 188.27 356 72 Example 13: 205.385.20% 186.2758685596526; Example 14: 204.285.10% 184.1700650520491; Example 15: 204.585.20% 182.1722663543482; Comparative Example 1: 20.950% 7.12001708936; Comparative Example 2: 205.585% 185.223019015080 In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0092] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A current collector, characterized in that, include: Current collector body; A buffer layer is disposed on the surface of the current collector body, the buffer layer comprising a conductive material that reacts with hydrogen sulfide.

2. The current collector according to claim 1, characterized in that, The pH of the buffer layer is 8 to 12.

3. The current collector according to claim 2, characterized in that, The pH of the buffer layer is 9 to 11.

4. The current collector according to claim 1, characterized in that, The conductive material is a base-containing conductive polymer.

5. The current collector according to claim 4, characterized in that, The conductive material is at least one of polyacetylene, polypyrrole, polythiophene, polyphenylene, polyphenylacetylene, and polyaniline.

6. The current collector according to claim 5, characterized in that, The conductive polymer has a molecular weight of 50,000 to 1,000,000; and / or the conductive polymer has a conductivity of 0.5 × 10⁻⁶. 2 S / cm~10×10 2 S / cm.

7. The current collector according to any one of claims 1-6, characterized in that, The thickness of the buffer layer is 0.5μm to 10μm.

8. A method for preparing the current collector according to any one of claims 1-7, characterized in that, The process includes the following steps: forming a buffer layer by placing a mixture containing a conductive material that reacts with hydrogen sulfide on the current collector body.

9. The method for preparing a current collector according to claim 8, characterized in that, The mixture is a liquid mixture, and the solid content of the liquid mixture is 5% to 20%.

10. The method for preparing a current collector according to claim 8 or 9, characterized in that, Adjust the pH of the mixture to 8-12.

11. The method for preparing a current collector according to claim 9, characterized in that, The liquid mixture is obtained by dissolving at least one conductive substance selected from polyacetylene, polypyrrole, polythiophene, polyphenylene, polyphenylacetylene, and polyaniline.

12. The method for preparing a current collector according to claim 11, characterized in that, The liquid mixture is coated onto the current collector body.

13. The method for preparing a current collector according to claim 12, characterized in that, The liquid mixture is coated by coating, pouring, immersion or spin coating.

14. A battery, characterized in that, The device includes a negative electrode sheet, the negative electrode sheet including a negative electrode current collector, the negative electrode current collector being a current collector according to any one of claims 1-7, or a current collector prepared by a method including a current collector according to any one of claims 8-13; and a negative electrode layer, the negative electrode layer including a negative electrode active material, the negative electrode active material including at least one of pure silicon, silicon carbide, graphite and silicon oxide.

15. The battery according to claim 14, characterized in that, Based on the weight of the negative electrode layer, the negative electrode layer also includes 5w% to 60w% electrolyte.

16. The battery according to claim 14, characterized in that, It also includes a positive electrode sheet, which comprises a positive electrode layer, the positive electrode layer comprising a positive electrode active material and a solid electrolyte, wherein the solid electrolyte comprises a Li-PS system, a sulfur-silver-germanium Li6PS5X system, or a lithium-germanium-phosphorus-sulfur Li... 10 GeP2S 12 At least one of the systems.

17. The battery according to claim 16, characterized in that, The positive electrode active material includes at least one of olivine-based materials, layered oxide materials, and spinel-based materials.

18. The battery according to claim 17, characterized in that, Based on the weight of the positive electrode layer, the content of the positive electrode active material is 50w% to 85w, and the content of the solid electrolyte is 5w% to 50w.

19. The battery according to claim 18, characterized in that, The positive electrode layer also includes a binder and a conductive agent. Based on the weight of the positive electrode layer, the content of the binder is 0.1w% to 10w, and the content of the conductive agent is 0.1w% to 10w.

20. A battery pack, characterized in that, It includes at least one battery according to any one of claims 14-19.

21. A battery pack, characterized in that, It includes at least one battery according to any one of claims 14-19, or includes at least one battery pack according to claim 20.

22. An electrical appliance, characterized in that, It includes at least one battery according to any one of claims 14-19, or at least one battery pack according to claim 20, or at least one battery pack according to claim 21.