Composite material, pole piece and battery

Abstract

The invention relates to the technical field of batteries, in particular to a composite material, a pole piece and a battery, and aims to solve the problem of how to improve stripping force reduction of the pole piece of the battery after rolling. The invention relates to a composite material, which is used for a pole piece of a battery and comprises a coupling agent and a first binder, the first binder comprises a first functional group, and the first functional group is configured to enable the first binder to be connected with the coupling agent through at least one mode of physical winding, Van der Waals force, covalent bonds and hydrogen bonds; the composite material comprises the following components in parts by weight: 10-70 parts of a coupling agent and 10-50 parts of a first binder.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a composite material, a pole piece and a battery. Background Art

[0002] The battery pole pieces have low peeling force after rolling. Currently, one method to improve the peeling force is to increase the amount of binder, but this will reduce the proportion of active materials and thus reduce the energy density; another method is to introduce a binder with stronger adhesion to improve the adhesion, but the glass transition temperature of the binder is high and it is relatively brittle, making it difficult for the battery pole pieces to withstand the mechanical stress formed by rolling, resulting in adhesion failure and reduced peeling force after rolling. Summary of the Invention

[0003] The purpose of this application is to provide a composite material, a pole piece and a battery, aiming to solve the problem of how to improve the peeling force of the battery pole piece after rolling.

[0004] In a first aspect, a composite material is provided for use in a battery electrode. The composite material includes a coupling agent and a first binder. The first binder includes a first functional group configured to connect the first binder and the coupling agent via at least one of physical entanglement, van der Waals forces, and hydrogen bonding.

[0005] The composite material includes: 10 to 70 parts by weight of a coupling agent and 10 to 50 parts by weight of a first binder.

[0006] The composite material provided in the present application is used for the electrode of a battery. First, the first binder of the composite material can form an interfacial bond with the electrode on the electrode, thereby improving the bonding strength between the composite material and the electrode. Second, the first functional group of the first binder is connected to the coupling agent through at least one of van der Waals force, physical entanglement and hydrogen bonding, thereby forming a stable network between the first binder and the coupling agent, thereby increasing the interfacial bonding strength between the first binder and the coupling agent. Moreover, the bifunctional group or multifunctional group of the coupling agent can form a chemical connection with the electrode, thereby serving as an auxiliary agent to enhance the interfacial bonding strength between the electrode and the first binder, thereby further increasing the bonding strength between the first binder and the electrode, thereby enhancing the interfacial bonding strength between the electrode and the composite material, thereby improving the peeling strength of the electrode.

[0007] At the same time, by setting the coupling agent in the range of 10 parts by weight to 70 parts by weight and the first adhesive in the range of 10 parts by weight to 50 parts by weight, a stable network can be formed between the coupling agent and the first adhesive, thereby enhancing the interfacial bonding force between the coupling agent and the first adhesive, thereby enhancing the interfacial bonding strength between the electrode and the composite material, thereby improving the peeling force of the electrode.

[0008] Optionally, the first functional group includes: a carboxyl group.

[0009] Optionally, the coupling agent includes a second functional group configured to form a bond with the first functional group of the first binder through at least one of physical entanglement, van der Waals forces, and hydrogen bonding. The second functional group includes at least one of an amino group, an amide group, a thiol group, an alkyl group, an isopropoxy group, an acetylacetonate group, and a polyether segment.

[0010] Optionally, the coupling agent further includes a third functional group, and the third functional group is configured to bond with the metal material in the electrode.

[0011] Optionally, after hydrolysis, the third functional group may form at least one of a Si-OH bond, a Zr-OH bond, an Al-OH bond, a Ti-OH bond, a P-OH bond, and a B-OH bond.

[0012] Optionally, the first binder further includes: a dynamic covalent bond.

[0013] Optionally, the dynamic covalent bond includes at least one of a disulfide bond, an imine bond, a urea bond, a borate bond, and a carbamate bond.

[0014] Optionally, the composite material further includes: 15 to 75 parts by weight of a second binder.

[0015] Optionally, the peel strength of the second adhesive is greater than or equal to 0.2 N / 40 mm.

[0016] Optionally, the second adhesive has a glass transition temperature in the range of -40°C to 120°C.

[0017] Optionally, the second adhesive includes at least one of sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polytetrafluoroethylene and ethylene vinyl acetate copolymer hot melt adhesive.

[0018] Optionally, the coupling agent includes at least one of a silane coupling agent, a titanate coupling agent, a zirconate coupling agent, a phosphate coupling agent, an aluminate coupling agent, and a borate coupling agent.

[0019] Optionally, the first adhesive is a self-healing polyurethane adhesive.

[0020] In a second aspect, a pole piece is provided, which includes a current collector, an adhesive layer, and an active layer.

[0021] The bonding layer is provided on at least one surface of the current collector, and the material forming the bonding layer includes a composite material.

[0022] The active layer is arranged on a side of the adhesive layer away from the current collector, and the material of the active layer includes an electrode material.

[0023] It can be understood that the beneficial effects that can be achieved by the electrode provided in the above embodiments of the present application can be referred to the beneficial effects of the electrode described above, and will not be repeated here.

[0024] Optionally, the material of the current collector includes a metal material, and the coupling agent further includes a third functional group, and the third functional group is configured to bond with the metal material in the current collector.

[0025] Optionally, the material of the active layer further includes: a first adhesive.

[0026] Optionally, the composite material further includes: a second binder; the material of the active layer further includes: a second binder.

[0027] Optionally, the thickness of the adhesive layer ranges from 0.5 μm to 1.5 μm.

[0028] Optionally, the ratio of the density of the material of the active layer to the density of the material of the bonding layer is in the range of 90-110.

[0029] Optionally, the active layer material has a density in the range of 100 g / m 2 ~300g / m 2 .

[0030] Optionally, the density of the adhesive layer material is in the range of 1 g / m 2 ~3g / m 2 .

[0031] Optionally, the electrode material includes: hard carbon material.

[0032] In a third aspect, a battery is provided, which includes a pole piece.

[0033] It can be understood that the beneficial effects that can be achieved by the battery provided in the above embodiments of the present application can be referred to the beneficial effects of the electrode described above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0035] Figure 1 A mechanism diagram of a pole piece is provided for an embodiment of the present application;

[0036] Figure 2 This is a mechanism diagram of the electrode in some other embodiments of the present application;

[0037] Figure 3This is a mechanism diagram of the electrode in some other embodiments of the present application;

[0038] Figure 4 A schematic structural diagram of a pole piece is provided for an embodiment of the present application.

[0039] Reference numerals:

[0040] 100, pole piece; 10, current collector; 20, bonding layer; 30, active layer. DETAILED DESCRIPTION

[0041] In the embodiments of the present application, the terms "first," "second," "third," "fourth," "fifth," and "sixth" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, a feature specified as "first," "second," "third," "fourth," "fifth," and "sixth" may explicitly or implicitly include one or more of the features.

[0042] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0043] An embodiment of the present application provides a battery comprising a pole piece 100 .

[0044] For example, the battery can be a sodium ion battery. Batteries are used in a wide range of fields, such as vehicles, mobile phones, electronic devices, etc.

[0045] Exemplarily, the electrode 100 can be a positive electrode or a negative electrode.

[0046] As you can understand, a battery's electrochemical reaction zone is formed by separating and connecting the positive and negative electrodes through an electrolyte. The positive electrode corresponds to oxidation reactions, while the negative electrode corresponds to reduction reactions. The positive electrode is the plate in the battery where oxidation reactions occur, and the negative electrode is the plate where reduction reactions occur. During battery discharge, the oxide in the positive electrode material loses oxygen atoms and releases electrons. These electrons flow to the negative electrode, where they conduct electrons through an external circuit, generating current.

[0047] The positive electrode sheet is primarily composed of an active material, a conductive agent, and a binder. The active material, such as a metal oxide, polymer, or other compound, chemically reacts with the active material in the negative electrode, releasing electrons. The conductive agent conducts these electrons, ensuring they flow from the positive electrode to the negative electrode.

[0048] The negative electrode is the part of the battery responsible for energy storage and is typically made of carbon material. Carbon materials have a high surface area and good electrical conductivity, effectively absorbing and storing ions. When the battery is discharged, the ions undergo a chemical reaction on the negative electrode, releasing electrons and forming new compounds. During charging, electrons flow from the external power source to the negative electrode, restoring the stored ions to their original form.

[0049] An embodiment of the present application provides a composite material for use in a battery electrode 100. The composite material includes a coupling agent and a first binder. The first binder includes a first functional group configured to connect the first binder and the coupling agent via at least one of physical entanglement, van der Waals forces, covalent bonds, and hydrogen bonds.

[0050] First, the first adhesive is on the electrode 100 and can form an interfacial bond with the electrode 100, thereby improving the bonding force between the composite material and the electrode 100; secondly, the first functional group of the first adhesive is connected to the coupling agent through at least one of physical entanglement, van der Waals force, covalent bond and hydrogen bond, thereby forming a stable network between the first adhesive and the coupling agent, thereby increasing the interfacial bonding force between the first adhesive and the coupling agent; moreover, the coupling agent has the characteristics of a double functional group or a multi-functional group, which can form a chemical connection with the electrode 100, and can be used as an auxiliary agent to enhance the interfacial bonding force between the electrode 100 and the first adhesive, thereby further increasing the bonding force between the first adhesive and the electrode 100, thereby enhancing the interfacial bonding strength between the electrode 100 and the composite material, thereby improving the peeling force of the electrode 100.

[0051] The composite material includes: 10 to 70 parts by weight of a coupling agent and 10 to 50 parts by weight of a first binder.

[0052] For example, the weight proportion of the coupling agent may be 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts or 70 parts, etc., which is not limited here.

[0053] For example, the weight proportion of the first binder may be 10 parts, 20 parts, 30 parts, 40 parts or 50 parts, etc., which is not limited here.

[0054] It can be understood that by setting the coupling agent in the range of 10 parts by weight to 70 parts by weight and the first adhesive in the range of 10 parts by weight to 50 parts by weight, a stable network can be formed between the coupling agent and the first adhesive, thereby enhancing the interfacial bonding force between the coupling agent and the first adhesive, and then enhancing the interfacial bonding strength between the electrode and the composite material, thereby improving the peeling force of the electrode 100.

[0055] In some embodiments, the first functional group includes: a carboxyl group.

[0056] It can be understood that the hydroxyl group (–OH) and carbonyl group (C=O) in the carboxyl group can form hydrogen bonds with the coupling agent, thereby enhancing the interfacial adhesion between the coupling agent and the first binder. Moreover, the polarity of the carboxyl group helps to improve the wettability and interfacial adaptability of the first binder, thereby enhancing the interfacial adhesion between the first binder and the electrode 100, thereby enhancing the peeling force of the electrode 100.

[0057] In some embodiments, the coupling agent includes a second functional group configured to connect to the first functional group of the first binder via at least one of physical entanglement, van der Waals forces, covalent bonding, and hydrogen bonding. The second functional group includes at least one of an amino group, an amide group, a thiol group, an alkyl group, an isopropoxy group, an acetylacetonate group, and a polyether segment.

[0058] It can be understood that the amino group, amide group, thiol group, isopropoxy group, acetylacetonate group, and the first functional group (such as carboxyl group) in the polyether segment in the second functional group are connected to the first binder through at least one of physical entanglement, van der Waals force, covalent bond and hydrogen bond. For example, the hydrogen atoms in the amino group (-NH2), amide group (-CONH-), and acetylacetonate group (ketone-bound nitrogen atom) can form hydrogen bonds with the oxygen-containing or nitrogen atoms in the first functional group to realize the connection between the coupling agent and the first binder; for example, the amino group and amide group can also form a covalent bond with the first functional group through a chemical reaction (such as amide formation, addition reaction); for example, the long chain structure of the polyether segment and the alkyl group forms a mechanical interlocking or van der Waals force through the entanglement of the segments to realize the connection between the coupling agent and the first binder, thereby forming a stable interface bridge between the coupling agent and the first binder, enhancing the interfacial bonding force between the coupling agent and the first binder, and thus enhancing the bonding strength between the electrode and the composite material.

[0059] In some embodiments, the coupling agent further includes a third functional group configured to bond with the metal material in the electrode 100 .

[0060] For example, the third functional group can bond with the metal material in the electrode 100 under drying conditions.

[0061] It can be understood that the third functional group in the coupling agent can bond with the metal material in the electrode 100 (such as copper and aluminum foil in the current collector), thereby enhancing the bonding force between the electrode 100 and the coupling agent. At the same time, hydrogen bonds can be formed between the coupling agent and the first adhesive. That is to say, the coupling agent can be used as an auxiliary agent to enhance the interfacial bonding force between the electrode 100 and the first adhesive, thereby improving the bonding force and stability of the composite material and the electrode 100, thereby improving the peeling force of the electrode 100 and enhancing the durability of the electrode 100 during rolling and cycling.

[0062] In some embodiments, the third functional group includes at least one of a Si-OH bond, a Zr-OH bond, an Al-OH bond, a Ti-OH bond, a P-OH bond, and a B-OH bond.

[0063] It can be understood that Si-OH bonds, Zr-OH bonds, Al-OH bonds, Ti-OH bonds, P-OH bonds and B-OH bonds can form stable chemical bonds with the metal material in the electrode 100 (such as forming metal-oxygen bonds), further enhancing the bonding force between the electrode 100 and the coupling agent, thereby improving the adhesion and stability of the composite material and the electrode 100, thereby improving the peeling force of the electrode 100 and enhancing the durability of the electrode 100 during rolling and cycling.

[0064] In some embodiments, the first binder further comprises: a dynamic covalent bond.

[0065] It can be understood that dynamic covalent bonds can break and reform to achieve reconfigurable self-healing. The introduction of dynamic covalent bonds in the first binder can make the first binder have reversible covalent connections, which can self-repair when stress and environment change. Therefore, under the mechanical stress of rolling or cycling process, the composite material can slow down the expansion of cracks through the breaking and repair of the covalent bonds of the first binder, so that the broken and damaged composite material can achieve self-healing, thereby maintaining the bonding force of the first binder, avoiding battery failure caused by failure of the first binder, and improving the overall performance and reliability of the battery.

[0066] In some embodiments, the dynamic covalent bond comprises at least one of a disulfide bond, an imine bond, a urea bond, a boronate bond, and a carbamate bond.

[0067] Understandably, the disulfide bond is a sulfur-sulfur bond formed by two sulfhydryl groups (-SH), which is relatively weak and easy to reversibly break and reassemble. The imine bond is formed by the reaction of an amine and an aldehyde or a ketone, is reversible, can be broken and reformed, and has excellent dynamic repair properties. The urea bond is a urea compound formed by the reaction of an amino group and a carboxylic acid chloride or an isocyanate, which is reversible, can be broken and reformed, and has dynamic repair properties. The borate bond is formed by boric acid and an alcohol or a hydroxyl compound, is reversible, can be broken and reformed, and has excellent dynamic repair properties; the carbamate bond is a dynamic covalent bond formed by a carbamate compound, which has good thermal stability and reversibility. Therefore, when the dynamic covalent bond includes at least one of a borate bond and a carbamate bond, the first adhesive can be broken and repaired under the mechanical stress of the rolling or cycling process, thereby maintaining the bonding force of the first adhesive, improving the overall bonding and stability of the electrode 100, thereby improving the peeling force of the electrode 100 and enhancing its durability during rolling and cycling.

[0068] In some embodiments, the composite material further includes: 15 parts by weight to 75 parts by weight of a second binder.

[0069] For example, the weight proportion of the second binder may be 15 parts, 25 parts, 35 parts, 45 parts, 55 parts, 65 parts or 75 parts, etc., which is not limited here.

[0070] It can be understood that a bonding force is formed between the second adhesive and the pole piece 100. Setting 15 to 75 parts by weight of the second adhesive can help strengthen the interface bonding force between the composite material and the pole piece 100, further improve the peeling force of the pole piece 100, and enhance its durability during rolling and cycling.

[0071] In some embodiments, the peel strength of the second adhesive is greater than or equal to 0.2 N / 40 mm.

[0072] For example, the peel strength of the second adhesive may be 0.2N / 40mm, 0.3N / 40mm, 0.4N / 40mm, 0.5N / 40mm, 0.6N / 40mm or 0.7N / 40mm, etc., which is not limited here.

[0073] It can be understood that setting the peel strength of the second adhesive to be greater than or equal to 0.2N / 40mm can make the second adhesive have higher bonding performance, further increase the interfacial bonding force between the composite material and the pole piece 100, improve the peel force of the pole piece 100, and enhance its durability during rolling and cycling.

[0074] In some embodiments, the second binder has a glass transition temperature ranging from -40°C to 120°C.

[0075] For example, the glass transition temperature of the second binder may be -40°C, -20°C, 0°C, 20°C, 40°C, 60°C, 80°C, 100°C or 120°C, etc., which is not limited here.

[0076] It can be understood that setting the glass transition temperature of the second adhesive within the range of -40°C to 120°C can make the second adhesive have good thermal stability and toughness within a wider temperature range, so that the composite material is not easy to be brittle during rolling and circulation, maintains good bonding performance, maintains the peeling force of the pole piece 100 after rolling, and enhances the durability of the pole piece 100 during rolling and circulation.

[0077] In some embodiments, the second adhesive includes at least one of sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polytetrafluoroethylene, and ethylene vinyl acetate copolymer hot melt adhesive.

[0078] It can be understood that sodium carboxymethyl cellulose (CMC) is an ionic cellulose gum with good water solubility and can form a transparent colloidal solution. Styrene-butadiene rubber (SBR) has good elasticity and toughness and is used to improve the elasticity and plasticity of the binder. As a second binder, SBR can provide good elasticity and wear resistance, which helps to stabilize the pole piece 100 during the charge and discharge process. Polyacrylic acid (PAA) has good adhesion and film-forming properties and can form complex bonds with metal ions or other active substances through its active groups, thereby improving the mechanical properties and electrochemical properties of the pole piece 100. Polyvinylidene fluoride (PVDF) is a highly non-reactive thermoplastic fluoropolymer with excellent chemical stability and adhesion. It can be used as a positive electrode binder, can resist the erosion of the electrolyte, while maintaining good adhesion properties, and can help maintain good contact between the active material and the conductive agent and the current collector. Polytetrafluoroethylene (PTFE) has an extremely low friction coefficient and excellent chemical stability, and can be used in combination with other materials to improve the overall performance of the pole piece 100. Ethylene vinyl acetate copolymer (EVA) hot melt adhesive has high bonding strength, toughness and heat resistance, and can also achieve rapid solidification through its hot melt properties, thereby forming a stable pole piece 100.

[0079] In some embodiments, the coupling agent includes at least one of a silane coupling agent, a titanate coupling agent, a zirconate coupling agent, a phosphate coupling agent, an aluminate coupling agent, and a borate coupling agent.

[0080] It is understood that the Si-OH groups after hydrolysis of the silane coupling agent can react with the metal material in the electrode 100 under drying conditions to form silicon-oxygen bonds (Si-OM), which firmly adhere to the surface of the electrode 100. The organic end groups (such as amino groups, amide groups, and polyether segments) in the silane coupling agent can react with the first binder to form hydrogen bonds.

[0081] After hydrolysis, the ester (–OR) groups of the titanate coupling agent react with the metal material in the electrode 100 under drying conditions to form a titanium-oxygen-metal surface (e.g., metal oxide) bond, forming a titanium-metal oxygen bond (Ti-OM). The organic end groups of the titanate coupling agent (e.g., isopropoxy, amino, or polyether segments) react with the first binder to form hydrogen bonds.

[0082] The Zr-OH groups in the hydrolyzed zirconate coupling agent can react with the metal material in the electrode 100 under drying conditions to form Zr-metal oxygen bonds (Zr-OM). The organic terminal functional groups in the zirconate coupling agent (e.g., acetylacetone, polyether segments) can react with the first binder to form hydrogen bonds.

[0083] The phosphate (–O–PO(OH)2) groups in the phosphate coupling agent can react with the metal material in the electrode 100 under drying conditions to form a stable phosphate-metal oxide bond, forming a P-metal oxygen bond (PO-Al). The organic terminal functional groups (such as amino groups, amide groups, and polyether segments) in the phosphate coupling agent can react with the first binder to form hydrogen bonds.

[0084] After hydrolysis, the ester groups (Al–OR) in the aluminate coupling agent can form an aluminum-oxygen-metal surface (aluminum oxide layer) chemical bond (Al–O–M) with the metal material in the electrode 100 under drying conditions. The organic terminal functional groups (such as amino groups, amide groups, and polyether segments) in the aluminate coupling agent can react with the first binder to form hydrogen bonds.

[0085] The borate ester (B-OH or B-OR) in the borate coupling agent can react with the metal material in the electrode 100 under drying conditions to form an interfacial bond. The organic terminal functional groups (such as amino groups, amide groups, and polyether segments) in the borate coupling agent can react with the first binder to form hydrogen bonds.

[0086] Therefore, the above-mentioned coupling agent includes: at least one of a silane coupling agent, a titanate coupling agent, a zirconate coupling agent, a phosphate coupling agent, an aluminate coupling agent and a borate coupling agent, all of which can react with the metal material in the pole piece 100, and can also react with the first adhesive to form a hydrogen bond, thereby improving the bonding strength and stability of the composite material and the pole piece 100, and further enhancing the overall bonding and stability of the pole piece 100, improving the peeling force of the pole piece 100, and enhancing its durability during rolling and cycling.

[0087] In some embodiments, the first adhesive is a self-healing polyurethane adhesive.

[0088] It can be understood that the polyurethane adhesive has good bonding properties and can form a strong bond with the pole piece 100 to ensure stable and good electrical connection of the pole piece 100.

[0089] In addition, the hydrogen bonds of the pole piece 100 are broken after rolling, resulting in a decrease in the peeling force after pressing. The dynamic covalent bonds, imine bonds, urea bonds and carbamate bonds contained in the self-healing polyurethane can re-form hydrogen bonds with the second adhesive (such as the carboxyl group in PAA), thereby reducing the peeling force reduction caused by rolling.

[0090] The embodiment of the present application provides a pole piece 100. Figure 4 As shown, the pole piece 100 includes: a current collector 10 , a bonding layer 20 and an active layer 30 .

[0091] The bonding layer 20 is disposed on at least one surface of the current collector 10 , and the bonding layer 20 is formed of a composite material.

[0092] The active layer 30 is disposed on a side of the adhesive layer 20 away from the current collector. The material of the active layer 30 includes an electrode material.

[0093] It is understood that the current collector 10 is a basic component of the pole piece 100, and its main function is to collect and transmit current. It is usually made of a metal with good conductive properties (such as copper, aluminum) or conductive materials to ensure efficient current transmission.

[0094] The bonding layer 20 connects the current collector 10 and the active layer 30, and its main function is to enhance the bonding force between the current collector 10 and the active layer 30, ensuring a close connection between the two. The bonding layer 20 is formed of a composite material, which is any of the composite materials in the above embodiments.

[0095] The electrochemical reaction zone at the core of the active layer 30 contains electrode materials (such as positive / negative electrode materials for lithium-ion and sodium-ion batteries) and is responsible for the energy storage and release of the battery.

[0096] In some examples, the polarity difference between the current collector 10 and the binder (such as SBR, PAA, polyurethane, etc.) is large, and the bonding force is mainly generated by mechanical riveting with the metal material. This poor bonding force leads to a low peel strength of the pole piece 100.

[0097] In some embodiments, the material of the current collector 10 includes a metal material, and the coupling agent further includes a third functional group, where the third functional group is configured to bond with the metal material in the current collector 10 .

[0098] It can be understood that the third functional group of the coupling agent can bond with the metal material in the current collector 10. As described above, the third functional group such as Si-OH bond, Al-OH bond, Zr-OH bond, Ti-OH bond, P-OH bond and B-OH bond can form a stable chemical bond (such as forming a metal-oxygen bond) with the metal material in the electrode 100 (for example, under drying conditions), further enhancing the bonding force between the electrode 100 and the coupling agent, thereby improving the adhesion and stability of the composite material and the electrode 100, thereby improving the peeling force of the electrode 100, and enhancing the durability of the electrode 100 during rolling and cycling.

[0099] In some embodiments, the material of the active layer 30 further includes: a first binder.

[0100] Exemplarily, the first adhesive may be a self-healing polyurethane adhesive.

[0101] It can be understood that, as described above, the first adhesive can form an interfacial bond with the electrode 100, which can enhance the bonding force between the composite material and the electrode 100; moreover, the first functional group in the first adhesive can be connected with the coupling agent through physical entanglement to form at least one of mechanical interlocking, van der Waals force, covalent bond and hydrogen bond, and a stable network can be formed between the first adhesive and the coupling agent, thereby increasing the interfacial bonding force between the first adhesive and the coupling agent, and further increasing the bonding force between the active layer 30 and the electrode 100, thereby enhancing the interfacial bonding strength between the active layer 30 and the electrode 100, thereby enhancing the peeling force of the electrode 100.

[0102] In some embodiments, the composite material further includes: a second binder. The material of the active layer 30 further includes: a second binder.

[0103] It can be understood that the second adhesive forms an adhesive force with the pole piece 100. Introducing the second adhesive into the active layer 30 can make the interface adhesive force between the active layer 30 and the pole piece 100 stronger, further improve the peeling force of the pole piece 100, and enhance its durability during rolling and cycling.

[0104] For example, the second binder may be at least one of CMC, SBR, PAA, PVDF, PTFE and EVA hot melt adhesive.

[0105] For example, combined Figures 1 to 3 An electrode material is provided on the current collector 10, and a coupling agent, a first binder and a second binder (such as PAA, SBR) are provided between the electrode material and the current collector 10, which can enhance the interfacial bonding force between the electrode material and the current collector 10; at the same time, a second binder (such as PAA, SBR) is also provided between the electrode materials, which can make the bonding force between the electrode material and the current collector 10 stronger, further improve the peeling force of the electrode sheet 100, and enhance its durability during rolling and cycling.

[0106] In some embodiments, the thickness of the adhesive layer 20 is in the range of 0.5 μm to 1.5 μm.

[0107] Illustratively, the thickness of the adhesive layer 20 may be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or 1.5 μm, etc., which is not limited here.

[0108] It can be understood that by setting the thickness of the bonding layer 20 within the range of 0.5 μm to 1.5 μm, the bonding layer 20 may have sufficient adhesion to ensure close bonding between the current collector 10 and the active layer 30, avoiding the situation where a thinner bonding layer 20 (such as <0.5 μm) may result in insufficient strength and poor adhesion, while a thicker bonding layer 20 (such as >1.5 μm) may increase brittleness and reduce the overall toughness of the electrode 100.

[0109] In some embodiments, the ratio of the density of the material of the active layer 30 to the density of the material of the bonding layer 20 is in the range of 90-110.

[0110] For example, the ratio of the density of the material of the active layer to the density of the material of the bonding layer may be 90, 95, 100, 105 or 110, etc., which is not limited here.

[0111] It can be understood that setting the ratio of the density of the material of the active layer 30 to the density of the material of the bonding layer 20 within the range of 90 to 110 can ensure that the current collector 10 and the active layer 30 maintain a good balance in mechanical properties and structural compatibility, avoid interfacial stress or low bonding efficiency caused by excessive density difference, and thereby improve the peeling force of the electrode 100 during rolling and cycling.

[0112] In some embodiments, the density of the material of the active layer 30 is in the range of 100 g / m 2 ~300g / m 2 .

[0113] For example, the density of the material of the active layer 30 may be 100 g / m 2 , 150g / m 2 , 200g / m 2 , 250g / m 2 or 300g / m 2 There is no limit here.

[0114] It is understandable that the density of the material of the active layer 30 is set to be 100 g / m 2 ~300g / m 2 Within this range, the amount of electrode active material can be guaranteed, the energy storage and release of the battery can be guaranteed, the active layer 30 can be ensured to maintain a good balance in mechanical properties and structural compatibility, and the peeling force of the pole piece 100 during rolling and cycling can be improved.

[0115] In some embodiments, the density of the material of the bonding layer 20 is in the range of 1 g / m 2 ~3g / m 2 .

[0116] For example, the density of the material of the adhesive layer 20 may be 1 g / m 2, 1.5g / m 2 , 2.0g / m 2 , 2.5g / m 2 or 3.0g / m 2 There is no limit here.

[0117] It is understandable that the density of the material of the adhesive layer 20 is set to be 1g / m 2 ~3g / m 2 Within this range, the bonding force between the current collector 10 and the active layer 30 can be ensured, the mechanical properties, bonding strength and stability of the bonding layer 20 as well as the overall structural stability can be ensured, and the peeling force of the pole piece 100 during rolling and cycling can be improved.

[0118] In some embodiments, the electrode material includes: a hard carbon material.

[0119] It can be understood that when the electrode material includes a hard carbon material, the electrode 100 can be used as a negative electrode. Due to the large specific surface area and porous characteristics of the hard carbon material, the negative electrode of the hard carbon material has a lower peeling force after rolling under the same formula. The present application introduces a coupling agent and a first adhesive into the adhesive layer 20, which can increase the bonding force between the first adhesive and the electrode 100, that is, the negative electrode, and thus enhance the interface bonding strength between the negative electrode and the composite material, thereby improving the peeling force of the negative electrode.

[0120] The present invention will be further described in detail below by taking several specific experiments as examples and in conjunction with the accompanying drawings.

[0121] Example 1

[0122] Embodiment 1 provides a pole piece 100. The method for preparing the pole piece 100 includes steps (1A) to (3A).

[0123] Step (1A): Coat a layer of a mixture containing a first binder, a second binder and a coupling agent on the surface of the current collector 10, and dry it to obtain a bonding layer 20 with a thickness of 0.5 μm; wherein the first binder is self-healing polyurethane, the amount of which is 15 parts by weight; the second binder is SBR, the amount of which is 75 parts by weight; and the coupling agent is a silane coupling agent, the amount of which is 10 parts by weight.

[0124] Step (2A): hard carbon, CMC, SBR, PAA, and self-healing polyurethane are prepared into a slurry at a mass ratio of 100:1:1:1:1, the slurry is coated on the bonding layer 20, and the active layer 30 is obtained by drying to form an initial electrode.

[0125] Step (3A): According to 0.98g / cm 3 The initial pole piece is rolled to obtain the pole piece 100 .

[0126] Example 2

[0127] Example 2 provides a pole piece 100. The preparation method of the pole piece 100 is the same as that of Example 1, except that the amount of the silane coupling agent used in step (1A) is 40 parts by weight.

[0128] Example 3

[0129] Example 3 provides a pole piece 100. The preparation method of the pole piece 100 is the same as that of Example 1, except that the amount of the silane coupling agent used in step (1A) is 70 parts by weight.

[0130] Example 4

[0131] Example 4 provides a pole piece 100. The preparation method of the pole piece 100 is the same as that of Example 1, except that the second binder in step (1A) is PAA in an amount of 75 parts by weight.

[0132] Example 5

[0133] Example 5 provides a pole piece 100. The preparation method of the pole piece 100 is the same as that of Example 4, except that the amount of the second binder PAA used in step (1A) is 40 parts by weight.

[0134] Example 6

[0135] Example 6 provides a pole piece 100. The preparation method of the pole piece 100 is the same as that of Example 4, except that the amount of the second binder PAA used in step (1A) is 70 parts by weight.

[0136] Example 7

[0137] Example 7 provides a pole piece 100. The preparation method of the pole piece 100 is the same as that of Example 1, except that the second adhesive in step (1A) is EVA hot melt adhesive in an amount of 75 parts by weight.

[0138] Example 8

[0139] Example 8 provides a pole piece 100. The preparation method of the pole piece 100 is the same as that of Example 7, except that the amount of the second adhesive EVA hot melt adhesive used in step (1A) is 40 parts by weight.

[0140] Example 9

[0141] Example 9 provides a pole piece 100. The preparation method of the pole piece 100 is the same as that of Example 7, except that the amount of the second adhesive EVA hot melt adhesive used in step (1A) is 70 parts by weight.

[0142] Example 10

[0143] Example 10 provides a pole piece 100. The method for preparing the pole piece 100 is the same as that of Example 1, except that the thickness of the adhesive layer 20 in step (1A) is 1 μm.

[0144] Example 11

[0145] Example 11 provides a pole piece 100. The preparation method of the pole piece 100 is the same as that of Example 1, except that the thickness of the adhesive layer 20 in step (1) is 1.5 μm.

[0146] Comparative Example 1

[0147] Comparative Example 1 provides a pole piece 100. The method for preparing the pole piece 100 includes steps (1B) to (2B).

[0148] Step (1B): hard carbon, CMC, and SBR are prepared into a slurry in a mass ratio of 100:1.5:2.5, the slurry is coated on the current collector 10, and the initial electrode is obtained by drying.

[0149] Step (2B): According to 0.98g / cm 3 The initial pole piece is rolled to obtain the pole piece 100 .

[0150] Performance testing

[0151] The electrode sheets 100 of the embodiment and the comparative example were subjected to peeling force tests, and the results are shown in Table 1.

[0152] Table 1 Peel strength of the electrode sheets 100 of the embodiment and the comparative example

[0153] Peel strength (N / 40mm) Example 1 0.25 Example 2 0.28 Example 3 0.30 Example 4 0.28 Example 5 0.31 Example 6 0.34 Example 7 0.27 Example 8 0.30 Example 9 0.32 Example 10 0.35 Example 11 0.45 Comparative Example 1 0.10

[0154] In the description of the embodiments of the present application, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0155] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A composite material for a battery pole piece, characterized in that: include: A coupling agent and a first binder; the first binder includes a first functional group, and the first functional group is configured to connect the first binder and the coupling agent by at least one of physical entanglement, van der Waals force, covalent bond and hydrogen bond; The composite material comprises: 10 to 70 parts by weight of a coupling agent and 10 to 50 parts by weight of a first binder.

2. The composite material according to claim 1, characterized in that The first functional group includes: a carboxyl group.

3. The composite material according to claim 1, characterized in that The coupling agent includes a second functional group, and the second functional group is configured to connect with the first functional group of the first binder through at least one of physical entanglement, van der Waals force, covalent bond and hydrogen bond; The second functional group includes at least one of an amino group, an amide group, a mercapto group, an alkyl group, an isopropoxy group, an acetylacetonate group, and a polyether segment.

4. The composite material according to claim 1, characterized in that The coupling agent further includes a third functional group, and the third functional group is configured to bond with the metal material in the pole piece.

5. The composite material according to claim 1, characterized in that After hydrolysis, the third functional group may form at least one of a Si-OH bond, a Zr-OH bond, an Al-OH bond, a Ti-OH bond, a P-OH bond, and a B-OH bond.

6. The composite material according to claim 1, characterized in that The first binder further comprises: a dynamic covalent bond.

7. The composite material according to claim 4, characterized in that The dynamic covalent bond includes at least one of a disulfide bond, an imine bond, a urea bond, a borate bond, and a carbamate bond.

8. The composite material according to any one of claims 1 to 7, characterized in that The composite material further includes: 15 to 75 parts by weight of a second binder.

9. The composite material according to claim 8, characterized in that The peel strength of the second adhesive is greater than or equal to 0.2N / 40mm; and / or, The glass transition temperature of the second binder is in the range of -40°C to 120°C.

10. The composite material according to claim 6, characterized in that The second adhesive includes at least one of sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polytetrafluoroethylene and ethylene vinyl acetate copolymer hot melt adhesive.

11. The composite material according to any one of claims 1 to 7, characterized in that The coupling agent includes at least one of a silane coupling agent, a titanate coupling agent, a phosphate coupling agent, a zirconate coupling agent, an aluminate coupling agent and a borate coupling agent.

12. The composite material according to any one of claims 1 to 7, characterized in that The first adhesive is a self-healing polyurethane adhesive.

13. A pole piece, characterized in that: include: current collector; a bonding layer provided on at least one surface of the current collector, wherein the bonding layer is formed of a material comprising the composite material according to any one of claims 1 to 12; The active layer is provided on a side of the adhesive layer away from the current collector, and the material of the active layer includes an electrode material.

14. The pole piece according to claim 13, characterized in that: The material of the current collector includes a metal material, and the coupling agent further includes a third functional group, and the third functional group is configured to bond with the metal material in the current collector.

15. The pole piece according to claim 13, characterized in that: The material of the active layer further includes: the first binder.

16. The pole piece according to claim 13, characterized in that: The composite material further includes a second binder; and the material of the active layer further includes the second binder.

17. The pole piece according to any one of claims 13 to 16, characterized in that: The thickness of the adhesive layer ranges from 0.5 μm to 1.5 μm.

18. The pole piece according to any one of claims 13 to 16, characterized in that: The ratio of the density of the material of the active layer to the density of the material of the bonding layer is in the range of 90 to 110.

19. The pole piece according to any one of claims 13 to 16, characterized in that: The density of the active layer material is in the range of 100 g / m 2 ~300g / m 2 and / or, The density of the material of the bonding layer is in the range of 1 g / m 2 ~3g / m 2 .

20. The pole piece according to any one of claims 13 to 16, characterized in that: The electrode material includes: hard carbon material.

21. A battery, characterized in that: include: The pole piece according to any one of claims 13 to 20.

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