Pole piece and preparation method and application thereof

Abstract

According to the pole piece and the preparation method and application thereof provided by the invention, a specific functional layer is designed on the end face of the pole piece, so that the stability of a current collector and the pole piece under electrolyte soaking and battery circulation conditions is effectively improved, that is, a metal layer or a conductive layer in the current collector is effectively prevented from falling off, and the service life of the pole piece is prolonged. Therefore, the structural stability of the current collector and the pole piece is greatly improved, and the cycling stability of the battery is optimized. And meanwhile, due to the design of the functional layer, the conductivity of the cut edge of the current collector or the pole piece can be effectively improved, the internal resistance of the battery is reduced, and the quality and reliability of the lithium ion battery are further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery current collectors, and in particular relates to a pole piece and a preparation method and application thereof. Background Art

[0002] The current collector plays the role of collecting current and supporting active materials in the electrode. Therefore, the current collector has an important influence on the performance of the electrode, and the electrode has an important influence on the performance of the battery. Therefore, further optimizing the performance of the current collector and the electrode is very important to meet the current demand for high-performance batteries.

[0003] Specifically, the mechanical and electrical properties of the current collector or electrode sheet significantly impact battery performance. Existing current collectors and electrode sheets often face performance degradation due to issues such as polymer deformation, metal layer shedding, conductive layer detachment, and low deposition efficiency, which in turn impact battery performance. These issues primarily stem from technical challenges in the current collector's material properties, manufacturing, and use.

[0004] Among them, the peeling of the metal layer or conductive layer is the most common problem in electrolytes and battery cycles. During the battery's charge and discharge process, the increase in temperature accelerates the diffusion reaction between the conductive layer and the binding layer, resulting in a decrease in the interlayer bonding strength between the conductive layer or metal layer and the base film such as PET, ultimately leading to the peeling of the conductive layer, affecting the safety and reliability of the battery. The lithium salt and water in the electrolyte synergistically exacerbate the peeling of the metal layer or conductive layer. Traditional methods optimize the base coating process (such as the aluminum oxide layer) or bake to remove water, but this cannot completely prevent interfacial corrosion caused by electrolyte penetration, especially corrosion of the end faces of the current collector or electrode, which in turn reduces the structural stability of the current collector and electrode, thereby reducing the battery's cycle performance and safety performance.

[0005] Furthermore, after trimming the current collector or electrode, the metal or conductive layers on both sides may suffer from poor conductivity due to burrs or oxidation. This can significantly increase the internal resistance of the battery. These trimming conductivity issues are often ignored or addressed through additional welding processes, increasing cost and complexity. Summary of the Invention

[0006] To address the problems and deficiencies in the prior art, the present invention provides a pole piece, a method for preparing the pole piece, and its application. By designing a specific functional layer on its end surface, the pole piece effectively improves the stability of the current collector and pole piece during electrolyte immersion and battery cycling. This effectively prevents the metal layer or conductive layer in the current collector from falling off, thereby significantly improving the structural stability of the current collector and pole piece, and optimizing the battery's cycling stability. Furthermore, the design of this functional layer can effectively improve the conductivity of the cut edges of the current collector or pole piece, reducing the battery's internal resistance, thereby improving the quality and reliability of the lithium-ion battery.

[0007] According to a first aspect of the present invention, a pole piece is provided, comprising a current collector, the current collector comprising a base film and a conductive layer disposed on at least one surface of the base film; the conductive layer comprising a metal layer, the metal layer comprising at least one of aluminum and copper; a functional layer is disposed on an end face of the pole piece, the functional layer comprising a conductive material, an organic resin, and a modifier; the mass ratio of the organic resin, the conductive material, and the modifier is 70-80:15-25:3-11; the conductive material comprises at least one of silver powder, copper powder, gold powder, nickel powder, graphite, graphene, carbon nanotubes, carbon black, carbon nanofibers, polyaniline, polypyrrole, polythiophene, and derivatives thereof. At least one; the modifier includes a silane coupling agent, and the silane coupling agent and the organic resin or the conductive layer or the conductive material meet at least one of the following conditions: (1) the silane coupling agent contains a functional group that reacts with the organic resin; (2) the hydrolyzate of the silane coupling agent contains a functional group that reacts with the organic resin; (3) the silane coupling agent contains a functional group that chemically adsorbs and / or physically adsorbs with the conductive layer, and / or the silane coupling agent contains a functional group that reacts with the hydroxyl group on the conductive layer; (4) the silane coupling agent contains a functional group that reacts with the conductive material; (5) the hydrolyzate of the silane coupling agent contains a functional group that reacts with the conductive material. At present, the focus of most current collectors or pole pieces on the market is often on the improvement of the large surface of the current collector or pole piece. The improvement of the large surface of the current collector or pole piece is relatively mature, and further improvement of the large surface of the current collector or pole piece is becoming increasingly difficult. However, with the increasing demand for high-performance batteries, even the improved current collectors or pole pieces cannot well meet the demand for high-performance batteries. Therefore, how to further improve the relevant performance of the current collector or electrode is of great significance for further optimizing the cycle performance and safety performance of the battery.

[0008] The electrode provided by the present invention differs from the conventional electrode designs described above in that it primarily focuses on the end face of the electrode (the end face of the electrode refers to the end face exposed during electrode trimming). A specific functional layer is designed on the end face of the electrode. This functional layer is composed of an organic resin, a conductive material, and a modifier in a specific mass ratio, with the modifier primarily being a silane coupling agent. At the specific mass ratio of the three materials, the organic resin and the conductive material, under the action of the modifier, can form a well-dispersed system, thereby forming a uniform, dense functional layer on the end face of the electrode. The silane coupling agent, in particular, can form a specific chemical or physical bond with the organic resin and / or the conductive layer and / or the material, enabling the resulting functional layer to have a good three-dimensional network, i.e., to make the resulting functional layer more resistant to electrolyte corrosion and have a higher bonding strength with the end face of the electrode, thereby further optimizing the performance of the electrode and battery.

[0009] Because the end faces of the pole pieces are usually cut, after cutting, the conductive layer (metal layer) in the current collector has poor conductivity due to cutting burrs or oxidation. This will increase the internal resistance of the battery after application, resulting in a decrease in battery cycle performance and safety performance. In addition, after slicing, due to the uneven end faces and many structural defects, the conductive layer (metal layer) is more likely to fall off from the base film during electrolyte immersion and battery cycling. Moreover, the lithium salt, water, electrolyte additives, organic solvents and other components in the electrolyte will penetrate and corrode from the end face of the pole piece over a long period of time, further exacerbating the conductive layer (metal layer) from falling off or peeling off from the base film, resulting in a decrease in the mechanical properties and conductive properties of the pole piece.

[0010] The present invention forms a uniform, dense functional layer on the end face of the electrode. Firstly, the functional layer comprises a conductive material that can connect the conductive layers (metal layers) on both sides of the end face formed by the cut edge of the electrode, thereby effectively reducing the resistance of the electrode cut edge end face (the conductive layer is part of the current collector structure, and the current collector performance affects the performance of the electrode), thereby effectively reducing the internal resistance of the battery prepared using the functional layer, and optimizing the battery's cycle performance and safety performance. Secondly, the functional layer can block the electrolyte's permeation path, thereby protecting the conductive layer (metal layer) in the current collector from easily falling off the base film, enhancing the structural stability of the current collector and the electrode as a whole under electrolyte and battery cycling, thereby further improving the battery's cycle stability and safety performance, that is, improving the battery's stability and reliability.

[0011] It should be noted here that providing the functional layer only on the end face of the electrode helps reduce costs and avoids the functional layer covering the large surface of the electrode, resulting in uneven thickness of the electrode, which affects the overall performance of the electrode. More importantly, such a design avoids interference with the ion transmission channels in the active material layer on the surface (large surface) of the electrode, helping to maintain good rate performance of the battery. At the same time, it reduces the coverage of the functional layer on the active material layer on the surface (large surface) of the electrode, reduces the risk of side reactions that may be caused by long-term contact between the functional layer and the electrolyte, and improves the long-term stability of the battery.

[0012] Furthermore, because the electrode is usually prepared by covering its surface with a positive or negative active material layer, the aforementioned electrode cutting problem also occurs when trimming the electrode. However, using the current collector to first make the electrode and then trimming it simplifies the overall process and can also improve the trimming problems of both the current collector and the electrode. Furthermore, using the current collector to first make the electrode and then trimming it can further simultaneously provide a sealing and protective effect for both the active material layer and the end face of the current collector (i.e., the electrode end face), which is more conducive to improving the overall structural stability and conductivity of the electrode composed of the active material layer and the current collector, and thus is more conducive to optimizing battery performance.

[0013] Preferably, the organic resin includes at least one of epoxy resin, phenolic resin, polyester resin, polyurethane resin, and silicone resin; the silane coupling agent includes at least one of γ-aminopropyltriethoxysilane (KH-550), γ-glycidyloxypropyltrimethoxysilane (KH-560), γ-mercaptopropyltrimethoxysilane (KH-590), vinyltri(2-methoxyethoxy)silane (A-172), β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KH-580), and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792).

[0014] Preferably, when the metal layer is an aluminum layer, in the functional layer of the pole piece end face, the conductive material includes at least one of silver powder, carbon nanotubes, and graphene, the organic resin includes epoxy resin, and the modifier includes at least one of γ-aminopropyltriethoxysilane (KH-550) and γ-glycidoxypropyltrimethoxysilane (KH-560); when the metal layer is a copper layer, in the functional layer of the pole piece end face, the conductive material includes at least one of silver powder, carbon nanotubes, and graphene, the organic resin includes epoxy resin, and the modifier includes at least one of γ-mercaptopropyltrimethoxysilane (KH-590) and vinyltris(2-methoxyethoxy)silane (A-172). The aluminum layer and the copper layer have different metallic properties, and therefore have different bonding abilities with the functional layer. By further configuring functional layers of different compositions according to the different metal layers, the functional layers can be better bonded to the pole piece end faces of different metal layers (the metal layer is part of the current collector, and the current collector is part of the pole piece). At the same time, the combination of the aforementioned materials also has good bonding ability with the active material layer end faces of the pole piece end faces. Therefore, under the above conditions, it is more conducive to enhancing the conductivity and electrolyte resistance of the pole piece end faces, thereby providing better conductivity and structural stability of the pole piece as a whole, thereby optimizing the battery's cycle performance and safety performance.

[0015] Specifically, when the metal layer is an aluminum layer, KH-550 and KH-560 are selected as modifiers. The silaneoxy group can hydrolyze to form silanol, condense with the hydroxyl group on the aluminum surface and react with the hydroxyl group in the epoxy resin to form a strong chemical bond. In addition, the silver powder and carbon nanotubes have strong conductivity. Under the above-mentioned modifiers, they can form a more uniformly dispersed system with the epoxy resin. Under the above-mentioned multiple effects, it is more conducive to enhancing the bonding force between the formed functional layer and the end face of the electrode. At the same time, the formed functional layer also has a more stable three-dimensional network structure, which is more conducive to optimizing the conductivity of the end face of the electrode, as well as the structural stability and electrolyte corrosion resistance of the electrode, thereby further optimizing the stability and reliability of the battery.

[0016] When the metal layer is a copper layer, KH-590 and A-172 are selected as modifiers, which can also make the silver powder and / or carbon nanotubes and / or graphene and epoxy resin form a more uniformly dispersed system, and can make the mixed system formed by the modifier, silver powder and epoxy resin better modify the end face of the pole piece (copper + base film), enhance the bonding force between the end face of the pole piece and the formed functional layer, and at the same time, the formed functional layer also has a more stable three-dimensional network structure, which is more conducive to optimizing the conductivity of the end face of the pole piece and the structural stability and resistance to electrolyte corrosion of the pole piece, thereby further optimizing the stability and reliability of the battery.

[0017] Preferably, when the metal layer is an aluminum layer, the conductive material in the functional layer on the electrode end face includes at least one of silver powder, carbon nanotubes, and graphene, the organic resin includes epoxy resin, and the modifier includes γ-aminopropyltriethoxysilane (KH-550). When the metal layer is a copper layer, the conductive material in the functional layer on the electrode end face includes at least one of silver powder, carbon nanotubes, and graphene, the organic resin includes epoxy resin, and the modifier includes γ-mercaptopropyltrimethoxysilane (KH-590). In particular, when the metal layer is an aluminum layer, KH-550 is further selected as the modifier because the amino reactive groups in its molecular structure can react with the epoxy groups in the epoxy resin, further enhancing the three-dimensional structural stability of the formed functional layer. This further improves the conductivity of the electrode end face and the overall structural stability of the electrode, prevents the conductive layer (metal layer) from shedding, and thus optimizes the battery's cycling stability and safety. When the metal layer is a copper layer, KH-590 is further selected as a modifier because the thiol group in its molecule can undergo chemical adsorption with the copper surface to form a stable chemical bond. Therefore, it is more conducive to improving the bonding ability between the electrode end face and the functional layer, thereby further promoting the improvement of the conductivity of the electrode end face and the overall stability of the electrode, and the improvement of the electrolyte corrosion resistance, preventing the conductive layer (metal layer) from falling off, thereby optimizing the cycle stability and safety of the battery.

[0018] Preferably, when the metal layer is aluminum, the functional layer on the electrode end face comprises a conductive material comprising at least one of silver powder, carbon nanotubes, and graphene, an organic resin comprising epoxy resin, and a modifier comprising γ-aminopropyltriethoxysilane (KH-550); the mass ratio of epoxy resin, conductive material, and γ-aminopropyltriethoxysilane being 75:20:5. Further limiting the mass ratio of conductive material, epoxy resin, and modifier is beneficial for enhancing the compatibility of the conductive material with the epoxy resin, improving the dispersion uniformity of the resulting mixed system, and enhancing the adhesion (binding strength) between the cured functional layer and the electrode end face (aluminum + base film). This also improves the conductivity of the electrode end face, thereby enhancing the overall structural stability, electrolyte corrosion resistance, and conductivity of the electrode, reducing the internal resistance of a battery fabricated using the electrode, and thereby optimizing the battery's cycling performance and safety.

[0019] Preferably, when the metal layer is a copper layer, the conductive material in the functional layer on the electrode end face includes at least one of silver powder, carbon nanotubes, and graphene, the organic resin includes epoxy resin, and the modifier includes γ-mercaptopropyltrimethoxysilane (KH-590); the mass ratio of epoxy resin, conductive material, and γ-mercaptopropyltrimethoxysilane (KH-590) is 75:15:10. Similarly, the combination of the conductive material, epoxy resin, and KH-590 not only ensures a uniform dispersion of the resulting mixed system, but also enhances the adhesion (binding strength) between the cured functional layer and the electrode end face (copper + base film), thereby further improving the overall structural stability, electrolyte corrosion resistance, and conductivity of the electrode, reducing the internal resistance of a battery fabricated using the electrode, and ultimately optimizing the battery's cycling performance and safety.

[0020] Preferably, the functional layer is composited with the end face of the electrode piece by at least one of the following methods: brushing, spraying, doctor blade coating, dispensing, screen printing, inkjet printing, dipping, physical vapor deposition, or chemical vapor deposition. In other words, it can be understood that the conductive paste is coated on the end face of the electrode piece by at least one of the following methods: brushing, spraying, doctor blade coating, dispensing, screen printing, inkjet printing, dipping, physical vapor deposition, or chemical vapor deposition, and then thermally cured to form the functional layer on the end face of the electrode piece; the conductive paste includes a conductive material, an organic resin, and a modifier.

[0021] Preferably, the functional layer is sprayed onto the end face of the electrode. The specific operation is as follows: a conductive paste is prepared using a conductive material, an organic resin, and a modifier, and the conductive paste is sprayed onto the end face of the electrode. After thermal curing, the functional layer is formed on the end face of the electrode. Preferably, the spraying conditions are as follows: the air pressure is controlled at 0.2-0.4 MPa, the movement speed of the spray gun or electrode is 5-20 mm / s, and the spraying distance is controlled at 10-20 cm.

[0022] Preferably, the thermal curing is performed at a temperature of 80-120° C. and a time of 10-30 minutes.

[0023] Preferably, the thickness of the functional layer on the end face of the pole piece is 0.05-0.2 mm. Controlling the thickness of the functional layer on the end face of the pole piece within the above range can ensure that the functional layer of a certain thickness effectively seals and protects the end face of the pole piece and effectively improves the conductivity of the end face of the pole piece, while preventing the functional layer from being too thick and affecting the overall performance of the pole piece, such as conductivity.

[0024] Preferably, in the current collector, the thickness of the base film is 4-10 μm.

[0025] Preferably, in the current collector, the thickness of the conductive layer is 0.5-2 μm.

[0026] Preferably, in the current collector, conductive layers are provided on both sides of the base film.

[0027] Preferably, the current collector also includes a transition layer, disposed between the base film and the conductive layer. Preferably, in the current collector, transition layers are provided on both sides of the base film. Preferably, the thickness of the transition layer is 5-20 nm. Preferably, the transition layer comprises at least one of a metal oxide and a metal compound; preferably, the metal oxide comprises at least one of aluminum oxide, titanium oxide, and zirconium oxide; and the metal compound comprises at least one of a nickel-chromium alloy, a nickel-phosphorus compound, a copper-nickel alloy, and a copper-nickel-chromium alloy. Adding a transition layer further improves the overall structural strength of the electrode sheet and the bonding strength of the various layers, optimizing various aspects of the electrode sheet's performance, including conductivity and structural stability.

[0028] Preferably, in the current collector, when the conductive layer is an aluminum layer, the transition layer is an aluminum oxide layer.

[0029] Preferably, in the current collector, when the conductive layer is a copper layer, the transition layer is a copper-nickel-chromium alloy layer.

[0030] Preferably, the current collector also includes a passivation layer. Adding a passivation layer helps improve the electrode's overall resistance to electrolyte corrosion, further improves the problem of the conductive layer (metal layer) easily peeling off from the base film, further improves the overall structural stability of the electrode, and further optimizes the cycling stability of the battery manufactured using the passivation layer.

[0031] Preferably, the thickness of the passivation layer is 3-8 nm.

[0032] Preferably, in the current collector, when the conductive layer is an aluminum layer, the passivation layer is obtained by aging the conductive layer in air for 18 to 30 hours.

[0033] Preferably, in the current collector, when the conductive layer is a copper layer, the passivation layer is formed by immersing the current collector in an anti-oxidation solution.

[0034] Preferably, the end face of the electrode is pretreated before the end face of the electrode is composited with the functional layer. The specific pretreatment steps are as follows: After protectively covering the non-end face portion of the electrode, the electrode is placed in a vacuum chamber and evacuated to a pressure of 5-50 Pa. Oxygen is then introduced as the working gas, with a gas flow rate controlled at 20-30 sccm. The RF power is set at 100-300 W, and the treatment time is 30-360 s. During the treatment process, high-energy particles in the plasma interact with the surface of the cut end face of the electrode, impacting surface atoms, causing sputtering and rearrangement, thereby increasing surface roughness. Simultaneously, active groups in the plasma bind to surface atoms, introducing polar groups and enhancing surface polarity. This specific pretreatment effectively improves the surface roughness of the electrode end face, providing more mechanical anchoring sites for the functional layer, enabling better adhesion of the functional layer to the end face and improving adhesion. At the same time, after the above-mentioned specific pretreatment, polar groups such as hydroxyl groups (—OH) can be introduced. The enhancement of surface polarity improves the interfacial wettability between the functional layer and the electrode, so that the conductive slurry can be spread more evenly during coating, spraying or deposition, further enhancing the bonding force between the two, ensuring that the functional layer is not easy to fall off during subsequent battery use, and maintains good sealing and conductive properties.

[0035] Preferably, when the metal layer in the electrode is aluminum, the RF power during pretreatment is 100-200 W, and the treatment time is 30-120 s. When the metal layer is aluminum, due to its relatively soft texture, to avoid excessive etching, selecting the above treatment conditions is more conducive to ensuring that the electrode is not damaged, and to avoid excessive etching that affects the overall structural stability, conductivity, and other properties of the electrode.

[0036] Preferably, when the metal layer in the electrode is a copper layer, the RF power during pretreatment is 200-300 W, and the treatment time is 180-300 s. When the metal layer is a copper layer, it has a higher hardness. Properly increasing the RF power can achieve a better effect of increasing surface roughness and polarity, that is, achieving a better pretreatment effect, which is more conducive to enhancing the bonding strength between the functional layer and the electrode end face, improving conductivity and electrolyte corrosion resistance, and optimizing the overall conductivity and cycle stability of the battery prepared using the copper layer.

[0037] Preferably, the formation of the functional layer on the end face of the electrode includes the following steps: S1. uniformly mixing an organic resin, a conductive material, and a modifier in an organic solvent to obtain a conductive paste; S2. coating the end face of the electrode with the conductive paste, and then forming a functional layer on the end face of the electrode after thermal curing. In the above step S2, it can be understood that the conductive paste is coated on the end face of the electrode by at least one of the following methods: brushing, spraying, scraping, dispensing, screen printing, inkjet printing, dipping, physical vapor deposition, chemical vapor deposition, and then forming a functional layer on the end face of the electrode after thermal curing.

[0038] Preferably, in S1, the conductive paste further includes a crosslinking agent, including hexamethoxymethyl melamine, in an amount of 2-5 wt% based on the total mass of the organic resin, conductive material, crosslinking agent, and modifier. The crosslinking agent reacts with active groups in organic resins, such as epoxy resins, during the curing process to form a three-dimensional crosslinked structure, thereby improving the curing degree and mechanical properties of the functional layer, and enhancing its tolerance to electrolytes and long-term stability.

[0039] Preferably, in S1, the organic solvent includes propylene glycol methyl ether acetate (PMA). An appropriate amount of the organic solvent can adjust the viscosity of the conductive paste, allowing it to have good fluidity during coating or deposition, facilitating uniform coating or deposition, and volatilize smoothly during the curing process without affecting the final performance of the functional layer.

[0040] Preferably, in S2, the thermal curing is performed at a temperature of 80-120°C and a time of 10-30 minutes.

[0041] According to a second aspect of the present invention, a battery is provided, comprising the aforementioned electrode sheet. The battery fabricated from the aforementioned electrode sheet exhibits low internal resistance and excellent cycle performance. In other words, the electrode sheet provided by the present invention is more conducive to obtaining a high-performance battery and is more adaptable to current demands for high-performance batteries. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0043] Example 1 1. Preparation of current collector The current collector of this embodiment (the metal layer is an aluminum layer) was prepared according to the following steps: In step A, a 6 μm thick PET film was placed in an evaporation machine, and a 10 nm thick aluminum oxide transition layer was deposited on both sides of the film. The specific process was as follows: high-purity aluminum wire (purity 99.93%) was used, the evaporation boat was heated to 1500°C, the gas source was oxygen at a flow rate of 80 mL / min, and the vacuum degree of the vacuum chamber was 0.1 Pa. Step B: Then, a 1 μm thick aluminum layer is deposited on the surface of the transition layer by using an evaporation coating process. The specific process is as follows: using high-purity aluminum wire (purity is 99.93%), heating the evaporation boat at 1500 °C, and the vacuum degree of the vacuum chamber at At this vacuum level, the impact of impurities in the air on the evaporation process can be effectively reduced, ensuring the purity and quality of the aluminum layer. Step C: The prepared product is aged in the air for 24 hours; the purpose of this step is to form a 5 nm aluminum oxide passivation layer on its surface.

[0044] The structure of the current collector prepared above is sequentially passivation layer, metal aluminum layer, transition layer, PET film, transition layer, metal aluminum layer, and passivation layer.

[0045] 2. Preparation of electrode (1) A positive electrode slurry is applied to both sides of the current collector prepared above to form a positive electrode active material layer, thereby finally preparing a positive electrode sheet. Specifically, the steps for preparing the positive electrode sheet are as follows: NCM811, a conductive agent (carbon nanotubes: Super P = 1:1), and PVDF are uniformly dispersed in polyvinyl pyrrolidone copper (NMP) at a mass ratio of 96:2:2 to obtain a positive electrode slurry, the positive electrode slurry is applied to both sides of the current collector prepared in this embodiment, and after drying, the positive electrode sheet is roll-formed to obtain a positive electrode sheet.

[0046] (2) Trim the positive electrode sheet obtained above according to the required size, and perform the following processing on the end surface of the positive electrode sheet (corresponding to the electrode sheet in the following steps): S0. After protectively covering the non-end surface portion of the electrode, the electrode is placed in a vacuum chamber and evacuated to a pressure of 30 Pa. Oxygen is then introduced as the working gas, with the gas flow rate controlled at 25 sccm. The RF power is set to 150 W, and the treatment time is 120 s. Prior to this step S0, the end surface of the electrode is usually treated to remove surface oil, impurities, etc. to ensure a clean surface. That is, regardless of whether the plasma pretreatment in S0 is performed, the functional layer covering the end surface of the electrode is subjected to the above cleaning treatment. S1. Evenly mix epoxy resin, silver powder, hexamethoxymethyl melamine, and γ-aminopropyl triethoxysilane (KH-550) in propylene glycol methyl ether acetate (PMA) to obtain a conductive paste. The mass ratio of epoxy resin, silver powder, and γ-aminopropyl triethoxysilane is 75:20:5. The amount of hexamethoxymethyl melamine is 2-5 wt% of the total mass of the epoxy resin, silver powder, hexamethoxymethyl melamine, and γ-aminopropyl triethoxysilane (KH-550). The amount of propylene glycol methyl ether acetate (PMA) is 10-20 wt% of the total mass of the epoxy resin, silver powder, hexamethoxymethyl melamine, and γ-aminopropyl triethoxysilane (KH-550). S2. Spray the conductive paste onto the end face of the electrode, and then heat-cure it (the heat-curing temperature is 80-120°C and the time is 10-30 minutes) to form a functional layer on the end face of the electrode; the thickness of the functional layer is 0.05 mm.

[0047] In the above S2, the specific operation of spraying is: (1) Equipment preparation: Select a precision sprayer, inspect and debug it to ensure that the nozzle is not blocked and the spray is uniform. Adjust the parameters of the spray gun such as air pressure, flow rate and spray distance. The air pressure is controlled at 0.2~0.4 MPa, the flow rate is adjusted according to the viscosity of the conductive paste and the required coating thickness (moving speed 5-20 mm / s), and the spray distance is controlled at 10~20 cm; (2) Fix the electrode that has been pre-treated in S0 on the fixture and spray it with the conductive paste prepared in S1. During the spraying process, keep the spray gun moving at a constant speed. Reciprocating spraying can be used to ensure that all parts of the cut edge are evenly sprayed with the conductive paste. At the same time, control the number of spraying times according to the required functional layer thickness. After each spraying, wait for the functional layer surface to dry slightly (about 5-10 minutes) before spraying again to avoid sagging.

[0048] (3) After spraying is completed, the functional layer is inspected for quality to see if the coating surface is uniform and whether there are any defects such as spray leaks, bubbles, or sagging. If any defects are found, they should be repaired or re-sprayed in a timely manner.

[0049] 3. Preparation of batteries (1) Positive electrode sheet: The positive electrode sheet prepared in this embodiment is used.

[0050] (2) Negative electrode sheet: Graphite, conductive agent, and binder are evenly dispersed in deionized water at a mass ratio of 95:2:3 to obtain a negative electrode slurry. The negative electrode slurry is coated on both sides of the copper foil, dried, and then roll-formed to obtain a negative electrode sheet.

[0051] (3) Electrolyte: lithium hexafluorophosphate As lithium salts, ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 1:1:1 as a solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0052] (4) Battery assembly: In a glove box filled with argon, the positive electrode sheet, separator (such as polyethylene separator), and negative electrode sheet are stacked in sequence, and then the electrolyte is injected to assemble a lithium-ion battery. After assembly, the battery is packaged to complete the battery preparation process.

[0053] Example 2 1. Preparation of current collector The preparation of the current collector in this embodiment is consistent with that in Example 1.

[0054] 2. Preparation of electrode The preparation of the electrode in this embodiment differs from that in Example 1 in that, during the processing of the electrode end face, in S1, the conductive material in the conductive paste is adjusted to carbon nanotubes, and the mass ratio of epoxy resin, carbon nanotubes, and γ-aminopropyltriethoxysilane is 75:20:5. The remaining steps are the same as in Example 1.

[0055] 3. Preparation of batteries The preparation of the battery in this example is the same as that in Example 1.

[0056] Example 3 1. Preparation of current collector The preparation of the current collector in this embodiment is consistent with that in Example 1.

[0057] 2. Preparation of electrode When processing the end face of the electrode, in S1, the modifier in the conductive paste was adjusted to γ-glycidyloxypropyltrimethoxysilane (KH-560), and the mass ratio of epoxy resin, silver powder, and γ-glycidyloxypropyltrimethoxysilane (KH-560) was 75:20:5. The remaining steps were the same as in Example 1.

[0058] 3. Preparation of batteries The preparation of the battery in this example is the same as that in Example 1.

[0059] Example 4 1. Preparation of current collector The preparation of the current collector in this embodiment is consistent with that in Example 1.

[0060] 2. Preparation of electrode When processing the end face of the electrode, in S1, the modifier in the conductive paste was adjusted to β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KH-580), and the mass ratio of epoxy resin, silver powder, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KH-580) was 75:20:5. Other conditions were the same as in Example 1.

[0061] 3. Preparation of batteries The preparation of the battery in this example is the same as that in Example 1.

[0062] Example 5 1. Preparation of current collector The preparation of the current collector in this embodiment is consistent with that in Example 1.

[0063] 2. Preparation of electrode When the end face of the electrode is processed, the pre-processing in S0 is not performed. The rest is the same as in Example 1.

[0064] 3. Preparation of batteries The preparation of the battery in this example is the same as that in Example 1.

[0065] Example 6 1. Preparation of current collector The current collector of this embodiment (the metal layer is a copper layer) is prepared according to the following steps: Step A: Place a 6 μm thick PET film in a magnetron sputtering chamber and evacuate to a vacuum level of Argon gas (flow rate 50 sccm) was introduced, and copper target and nickel-chromium alloy target (target quantity ratio 14-13:1-2) were sputtered on both sides of the PET film with a power of 200 W and a deposition time of 5 min to form a 5-10 nm transition layer.

[0066] Step B: With the plated workpiece (magnetron film) as cathode and the pure copper plate as anode, a copper layer is deposited on both sides of the plated workpiece (magnetron film) in an electroplating solution consisting of 200 g / L copper sulfate, 50 g / L sulfuric acid, 50 ppm chloride ions, a leveler, and a brightener. The current density is , electroplating time 10-20 min; Step C: After plating, rinse with deionized water and blow dry, then immerse in antioxidant solution for 30 seconds to form a 5 nm passivation layer.

[0067] The structure of the current collector prepared above is sequentially passivation layer, metal copper layer, transition layer, PET film, transition layer, metal copper layer, and passivation layer.

[0068] 2. Preparation of electrode (1) A negative electrode slurry is applied to both sides of the current collector prepared above to form a negative electrode active material layer, thereby finally preparing a negative electrode sheet. Specifically, the steps for preparing the negative electrode sheet are as follows: graphite, a conductive agent, and a binder are uniformly dispersed in deionized water at a mass ratio of 95:2:3 to obtain a negative electrode slurry; the negative electrode slurry is applied to both sides of the current collector prepared in this embodiment; and after drying, the negative electrode slurry is roll-formed to obtain a negative electrode sheet.

[0069] (2) The negative electrode sheet obtained above was trimmed according to the required size, and the end surface of the negative electrode sheet was treated similarly to steps S0 to S2 in Example 1. The difference from Example 1 was that in S0, the RF power was set to 300 W and the treatment time was 240 s. In S1, the conductive paste was replaced with γ-aminopropyltriethoxysilane (KH-550) and the mass ratio of epoxy resin, silver powder, and γ-mercaptopropyltrimethoxysilane (KH-590) was 75:15:10. The rest of the process was the same as in Example 1.

[0070] The thickness of the functional layer finally formed on the end surface of the negative electrode sheet was 0.05 mm.

[0071] 3. Preparation of batteries (1) Positive electrode sheet: NCM811, conductive agent (carbon nanotubes: Super P = 1:1), and PVDF are evenly dispersed in polyvinyl pyrrolidone copper (NMP) at a mass ratio of 96:2:2 to obtain a positive electrode slurry. The positive electrode slurry is coated on both sides of the aluminum foil, dried, and then roll-formed to obtain a positive electrode sheet.

[0072] (2) Negative electrode sheet: The negative electrode sheet prepared in this embodiment is used.

[0073] (3) Electrolyte: the same as in Example 1.

[0074] (4) Battery assembly: the same as in Example 1.

[0075] Example 7 1. Preparation of current collector The preparation of the current collector in this embodiment is consistent with that in Example 6.

[0076] 2. Preparation of electrode The preparation of the electrode in this embodiment differs from that in Example 6 in that, during the processing of the electrode end face, in S1, the mass ratio of epoxy resin, silver powder, and γ-mercaptopropyltrimethoxysilane (KH-590) in the conductive paste is adjusted to 75:20:5. The remaining steps are the same as in Example 6.

[0077] 3. Preparation of batteries The preparation of the battery in this example is consistent with that in Example 6.

[0078] Example 8 1. Preparation of current collector The preparation of the current collector in this embodiment is consistent with that in Example 6.

[0079] 2. Preparation of electrode The preparation of the electrode in this example differs from that in Example 6 in that, during the treatment of the end face of the current collector, in step S1, the conductive material in the conductive paste is adjusted to graphene, and the mass ratio of epoxy resin, graphene, and γ-mercaptopropyltrimethoxysilane (KH-590) is 75:15:10. The remaining steps are the same as in Example 6.

[0080] 3. Preparation of batteries The preparation of the battery in this example is consistent with that in Example 5.

[0081] Example 9 1. Preparation of current collector The preparation of the current collector in this embodiment is consistent with that in Example 6.

[0082] 2. Preparation of electrode The preparation of the electrode in this example differs from that in Example 6 in that, during the treatment of the end face of the current collector, in step S1, the epoxy resin in the conductive paste is replaced with a silicone resin, and the mass ratio of the silicone resin, silver powder, and γ-mercaptopropyltrimethoxysilane (KH-590) is 70:15:10. The remaining steps are the same as in Example 6.

[0083] 3. Preparation of batteries The preparation of the battery in this example is consistent with that in Example 6.

[0084] Example 10 1. Preparation of current collector The preparation of the current collector in this embodiment is consistent with that in Example 6.

[0085] 2. Preparation of electrode The preparation of the electrode in this example differs from that in Example 6 in that, during the treatment of the electrode end face, in S1, the modifier in the conductive paste is adjusted to N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792), and the mass ratio of epoxy resin, silver powder, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792) is 75:15:10. The remaining steps are the same as in Example 6.

[0086] 3. Preparation of batteries The preparation of the battery in this example is consistent with that in Example 6.

[0087] Example 11 1. Preparation of current collector The preparation of the current collector in this embodiment is consistent with that in Example 1.

[0088] 2. Preparation of electrode The difference between the preparation of the electrode in this embodiment and that in embodiment 1 is that when the end face of the electrode is processed, the thickness of the functional layer on the end face of the electrode is adjusted by controlling the spraying thickness of the conductive paste. m The rest is consistent with Example 1.

[0089] 3. Preparation of batteries The preparation of the battery in this example is the same as that in Example 1.

[0090] Example 12 1. Preparation of current collector The preparation of the current collector in this embodiment is consistent with that in Example 1.

[0091] 2. Preparation of electrode The preparation of the electrode in this embodiment differs from that in Example 1 in that, when processing the end face of the electrode, the thickness of the conductive paste sprayed is adjusted so that the thickness of the functional layer on the end face of the electrode is 0.03 mm. The rest of the steps are the same as in Example 1.

[0092] 3. Preparation of batteries The preparation of the battery in this example is the same as that in Example 1.

[0093] Comparative Example 1 1. Preparation of current collector The preparation of the current collector in this comparative example is consistent with that in Example 1.

[0094] 2. Preparation of electrode The preparation of the electrode in this comparative example is different from that in Example 1 in that the end surface of the electrode is not processed. The rest is the same as in Example 1.

[0095] 3. Preparation of batteries The preparation of the battery in this comparative example is consistent with that in Example 1.

[0096] Comparative Example 2 1. Preparation of current collector The preparation of the current collector in this comparative example is consistent with that in Example 1.

[0097] 2. Preparation of electrode The preparation of the electrode in this comparative example differs from that in Example 1 in that, when processing the end surface of the electrode, the conductive paste in S1 does not contain silver powder.

[0098] 3. Preparation of batteries The preparation of the battery in this comparative example is consistent with that in Example 1.

[0099] Comparative Example 3 1. Preparation of current collector The preparation of the current collector in this comparative example is consistent with that in Example 1.

[0100] 2. Preparation of electrode The preparation of the electrode in this comparative example differs from that in Example 1 in that, when processing the end face of the electrode, the conductive paste in S1 does not contain γ-aminopropyltriethoxysilane (KH-550). The rest is the same as in Example 1.

[0101] 3. Preparation of batteries The preparation of the battery in this comparative example is consistent with that in Example 1.

[0102] Comparative Example 4 1. Preparation of current collector The preparation of the current collector in this comparative example is consistent with that in Example 1.

[0103] 2. Preparation of electrode The preparation of the electrode in this comparative example differs from that in Example 1 in that, when treating the end face of the electrode, the mass ratio of epoxy resin, silver powder, epoxy resin, and γ-aminopropyltriethoxysilane in the conductive paste in S1 is 60:35:5. The remaining steps are the same as in Example 1.

[0104] 3. Preparation of batteries The preparation of the battery in this comparative example is consistent with that in Example 1.

[0105] Test Case 1. Experimental Construction Method (1) The electrode pieces in Examples 1 to 12 and Comparative Examples 1 to 4 (the electrode pieces in Examples 1 to 12 and Comparative Examples 2 to 4 were covered with the end surface functional layer, and the electrode piece in Comparative Example 1 was not covered with the end surface functional layer) were tested for electrolyte immersion shedding time, cut edge end surface contact resistance, and adhesion strength. The specific test methods are as follows: Electrolyte immersion and shedding time: The electrode is immersed in the electrolyte. When the transition layer between the metal layer (conductive layer) of the current collector and the PET in the electrode falls off, causing the aluminum layer to peel off from the surface of the PET base film along with the transition layer, it is recorded as the electrolyte immersion and shedding time. The electrolyte contains the following components: solvent: ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), etc. (usually in a volume ratio of 1:1:1); lithium salt: lithium hexafluorophosphate ( , concentration 1 mol / L); additives: such as vinylene carbonate (VC), and / or fluoroethylene carbonate (FEC), etc. (content ≤5%).

[0106] Cut edge end surface contact resistance: Two-probe method (DC four-terminal method). Fix the electrode end surface to the fixture to ensure that the cut surface is vertical; use two microprobes (tip diameter <100μm) to contact the metal layers (conductive layers, such as aluminum or copper) on both sides of the end surface, apply a constant current (such as 1mA), and measure the voltage drop; calculate the resistance (R=V / I) according to Ohm's law, the unit is .

[0107] Adhesion: Attach the electrode sample to the fixture, ensuring a secure and smooth adhesion. Start the electronic universal tester and peel the electrode at a set speed at a 90° angle. During the peeling process, observe and record the change in adhesion over time. A tension sensor located on the dynamic chuck and a built-in displacement sensor are used to measure changes in tension and displacement during the test, allowing calculation of the electrode adhesion. Adhesion = maximum sample tension (N) / sample width (m).

[0108] (2) The internal resistance and cycle capacity retention rate of the batteries in Examples 1 to 12 and Comparative Examples 1 to 4 were tested. The specific testing methods are as follows: Battery internal resistance: Equipment: Battery testing system (such as Xinwei CT-4008).

[0109] Testing process: 1. Let the battery sit for 30 minutes until the voltage stabilizes; 2. Apply a constant current pulse (such as a 1C discharge pulse) lasting 1-10 seconds; 3. Record the voltage change within 10-100ms after the pulse starts (avoid polarization effects).

[0110] Data calculation: Take the voltage change at the initial stage of the pulse (e.g. 50ms) to calculate the ohmic internal resistance. The formula is: .

[0111] Battery internal resistance increase rate = .

[0112] Cycle capacity retention rate: The battery is charged and discharged 1000 times at a charge and discharge rate of 1C, and the initial capacity of the battery is recorded. The battery capacity after 1000 cycles of charge and discharge is estimated, that is, capacity retention rate = battery capacity after 1000 cycles of charge and discharge / initial capacity of the battery × 100%.

[0113] 2. Experimental Results The test results of the electrolyte immersion shedding time, cut edge end surface contact resistance and bonding strength of the electrode sheets in Examples 1 to 12 and Comparative Examples 1 to 4 are shown in Table 1. The internal resistance and cycle capacity retention rate of the batteries in Examples 1 to 12 and Comparative Examples 1 to 4 are also shown in Table 1.

[0114] Table 1 Test results of relevant performance of electrodes and batteries in the examples and comparative examples

[0115] As can be seen from Table 1, the present invention can effectively improve the structural stability and conductivity of the electrode piece by designing a specific functional layer on the end face of the electrode piece, which is manifested in improved electrolyte resistance of the electrode piece, reduced resistance of the cut edge end face, and improved bonding strength, thereby effectively reducing the increase rate of the battery internal resistance and improving the cycle capacity retention rate of the battery. For details, please refer to the performance data of Examples 1 to 12.

[0116] In Comparative Example 1, the electrode sheet's rear end surface was left untreated after trimming, significantly reducing its electrolyte immersion time (to 3 days). Simultaneously, the end surface resistance increased significantly, while adhesion decreased significantly. This significantly increased the rate of increase in battery internal resistance and decreased the battery's cycle capacity retention. This demonstrates that the functional layer can block electrolyte penetration by sealing the end surface. Furthermore, the functional layer directly connects the metal layers on both sides of the trimmed edge, forming a low-resistance path. Therefore, the functional layer effectively improves the electrode sheet's electrolyte resistance, reduces end surface resistance, and enhances adhesion, thereby optimizing the battery's cycling performance.

[0117] In Comparative Example 2, the functional layer applied to the rear end face of the electrode after trimming did not contain any conductive material; in Comparative Example 3, the functional layer applied to the rear end face of the electrode after trimming did not contain any modifier (silane coupling agent); and in Comparative Example 4, the mass ratio of epoxy resin, silver powder, and γ-aminopropyltriethoxysilane was outside the range of 70-80:15-25:3-11. These factors all resulted in reduced electrode electrolyte resistance, increased trim end face resistance, reduced adhesion, an increased rate of increase in battery internal resistance, and a decrease in battery cycle capacity retention. This demonstrates that the presence and mass ratio of materials such as organic resin, conductive material, and modifier significantly impact the electrode structural stability and conductivity, and thus, battery performance.

[0118] Further comparisons between Examples 1 and 2-5 reveal that, compared to Example 1, the conductive material in the functional layer of Example 2, carbon nanotubes, resulted in better electrode and battery performance. Compared to Example 1, the functional layer of Example 3, in which the modifier was γ-glycidoxypropyltrimethoxysilane (KH-560), exhibited slightly worse electrode and battery performance. Compared to Example 1, the functional layer of Example 4, in which the modifier was β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KH-580), exhibited slightly worse electrode and battery performance compared to Examples 1 and 3. These results suggest a certain interaction between the organic resin, conductive material, and modifier. Choosing the right combination of these three materials and a specific mass ratio can improve the structural stability and conductivity of the electrode, thereby further optimizing battery performance.

[0119] Comparing Example 1 and Example 5, compared with Example 1, in Example 5, when the end face of the electrode was processed in the functional layer, the pretreatment in S0 was not performed, resulting in a decrease in the performance of the electrode and the battery in Example 5. This shows that performing specific pretreatment on the end face of the electrode before covering with the functional layer is more conducive to improving the bonding ability between the end face of the electrode and the functional layer, further improving the structural stability and conductivity of the electrode, and achieving the purpose of further optimizing battery performance.

[0120] Observing Example 1 and Example 6, the metal layer in the current collector in Example 6 is a copper layer, and the material used in the functional layer also changes with the change of the metal layer material. This shows that materials such as silane coupling agents have directional adaptability. Regulating the material adaptability of the functional layer according to the different metal layers is more conducive to obtaining highly stable and highly conductive electrodes, thereby further optimizing the performance of the battery.

[0121] Comparing Examples 6 and 7-10, the mass ratio of epoxy resin, silver powder, and γ-mercaptopropyltrimethoxysilane (KH-590) in the functional layer of Example 7 is 75:20:5 compared to Example 6. Compared to Example 6, the conductive material in the functional layer of Example 8 is graphene. Compared to Example 6, the organic resin in the functional layer of Example 8 is silicone resin. Compared to Example 6, the modifier in the functional layer of Example 10 is N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792). These changes demonstrate that changing the current collector metal layer material also requires adaptively changing the functional layer material to improve compatibility between the functional layer and the electrode end face, further enhancing the electrode's structural stability and conductivity, and optimizing battery performance. Similarly, it can be seen that there is a certain interaction between the organic resin, conductive material, and modifier. Choosing the right combination of these three materials and a specific mass ratio is more conducive to achieving an electrode with enhanced structural stability and conductivity, thereby further optimizing battery performance.

[0122] Comparing Example 1 with Examples 11 and 12, the functional layers on the electrode end faces in Examples 11 and 12 were respectively too thick and too thin, which led to a decrease in electrode and battery performance. This indicates that the thickness of the functional layer also has a certain impact on the electrode structural stability and conductivity. An appropriate thickness is more conducive to balancing electrode structural stability, conductivity, and other aspects of performance, and is more conducive to improving overall battery performance.

[0123] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents, but these modifications or replacements are all within the scope of protection of the present invention.

Claims

1. A pole piece, characterized in that: The pole piece includes a current collector, and the current collector includes a base film and a conductive layer provided on at least one side surface of the base film; The conductive layer includes a metal layer, and the metal layer includes at least one of aluminum and copper; The end surface of the pole piece is provided with a functional layer, and the functional layer comprises a conductive material, an organic resin, and a modifier; The mass ratio of the organic resin, the conductive material, and the modifier is 70-80:15-25:3-11; The conductive material includes at least one of silver powder, copper powder, gold powder, nickel powder, graphite, graphene, carbon nanotubes, carbon black, carbon nanofibers, polyaniline, polypyrrole, polythiophene and derivatives thereof; The modifier includes a silane coupling agent, and the silane coupling agent and the organic resin, the conductive layer, or the conductive material meet at least one of the following conditions: (1) The silane coupling agent contains a functional group that reacts with the organic resin; (2) The hydrolyzate of the silane coupling agent contains a functional group that reacts with the organic resin; (3) The silane coupling agent contains a functional group that chemically absorbs and / or physically absorbs the conductive layer, and / or the silane coupling agent contains a functional group that reacts with the hydroxyl group on the conductive layer; (4) The silane coupling agent contains a functional group that reacts with the conductive material; (5) The hydrolyzate of the silane coupling agent contains a functional group that reacts with the conductive material.

2. The pole piece according to claim 1, characterized in that: The organic resin includes at least one of epoxy resin, phenolic resin, polyester resin, polyurethane resin, and silicone resin; The silane coupling agent includes at least one of γ-aminopropyltriethoxysilane (KH-550), γ-glycidoxypropyltrimethoxysilane (KH-560), γ-mercaptopropyltrimethoxysilane (KH-590), vinyltri(2-methoxyethoxy)silane (A-172), β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KH-580), and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (KH-792).

3. The pole piece according to claim 1, wherein: When the metal layer is an aluminum layer, in the functional layer on the end surface of the electrode, the conductive material includes at least one of the silver powder, the carbon nanotubes, and the graphene, the organic resin includes the epoxy resin, and the modifier includes at least one of γ-aminopropyltriethoxysilane (KH-550) and γ-glycidoxypropyltrimethoxysilane (KH-560); When the metal layer is a copper layer, in the functional layer on the end face of the pole piece, the conductive material includes at least one of the silver powder, the carbon nanotubes, and the graphene, the organic resin includes the epoxy resin, and the modifier includes at least one of the γ-mercaptopropyltrimethoxysilane (KH-590) and the vinyl tris(2-methoxyethoxy)silane (A-172).

4. The pole piece according to claim 3, characterized in that: When the metal layer is an aluminum layer, in the functional layer on the end surface of the electrode, the conductive material includes at least one of the silver powder, the carbon nanotubes, and the graphene, the organic resin includes the epoxy resin, and the modifier includes γ-aminopropyltriethoxysilane (KH-550); When the metal layer is a copper layer, in the functional layer on the end face of the pole piece, the conductive material includes at least one of the silver powder, the carbon nanotubes, and the graphene, the organic resin includes the epoxy resin, and the modifier includes γ-mercaptopropyltrimethoxysilane (KH-590).

5. The pole piece according to claim 1, characterized in that: The thickness of the functional layer on the end face of the pole piece is 0.05-0.2 mm.

6. The pole piece according to claim 1, characterized in that: The functional layer is compounded with the end face of the pole piece by at least one of the following methods: brushing, spraying, scraping, dispensing, screen printing, inkjet printing, dipping, physical vapor deposition, and chemical vapor deposition.

7. The pole piece according to claim 1, characterized in that: The formation of the functional layer on the end surface of the pole piece includes the following steps: S1. The organic resin, the conductive material, and the modifier are uniformly mixed in an organic solvent to obtain a conductive paste; S2. Covering the end surface of the electrode with the conductive paste, and then forming the functional layer on the end surface of the electrode after thermal curing.

8. The pole piece according to claim 7, characterized in that: The end surface of the pole piece is pre-processed, and then the end surface of the pole piece and the functional layer are composited; The specific operation of the pretreatment is as follows: after protectively covering the non-end surface part of the electrode, the electrode is placed in a vacuum chamber and evacuated to a pressure of 5~50 Pa, and then oxygen is introduced as the working gas, the gas flow rate is controlled at 20~30 sccm, the RF power is set to 100~300 W, and the processing time is 30~360 s.

9. The pole piece according to claim 7, characterized in that: In S1, the conductive paste further includes a crosslinking agent, the crosslinking agent includes hexamethoxymethyl melamine, and the amount of the crosslinking agent is 2-5 wt % of the total mass of the organic resin, the conductive material, the crosslinking agent, and the modifier.

10. A battery, characterized in that: Comprising the pole piece as claimed in any one of claims 1 to 9.

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