Electrode film, electrode sheet, and battery

Abstract

An electrode film, an electrode sheet, and a battery. The electrode film comprises a fiber, the ratio of the length to the diameter of the fiber being L1, wherein L1 is 10-1,000, and preferably, L1 is 20-500. By limiting the composition of the electrode film and the length-diameter ratio of the fiber, the structural strength and bonding property of the electrode film can be remarkably improved, thereby ensuring that all components in the electrode film are kept in a good bonding state; and by applying the electrode film to a battery, the cycle performance and rate performance of the battery can be remarkably improved.

Description

Electrode film, electrode sheet and battery

[0001] This disclosure claims priority to the Chinese patent application filed with the China Patent Office on December 26, 2023, with application number 202311805038.1 and application name “An electrode membrane, electrode sheet and battery”, the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0002] The present disclosure relates to the technical field of lithium-ion batteries, and in particular to an electrode film, an electrode sheet, and a battery. Background Art

[0003] Lithium-ion batteries are widely used in portable electronic products, new energy vehicles and other fields due to their advantages such as high energy utilization efficiency and environmental friendliness. Electrodes, as important components of lithium-ion batteries, have a crucial impact on the performance of lithium-ion batteries. Currently, in the manufacturing process of electrodes, a series of steps such as mixing, homogenization, coating, drying and rolling are performed to finally obtain electrodes of suitable thickness. However, a large amount of solvent is required in the homogenization process, and the solvent needs to be dried and removed later, resulting in a huge waste of energy and an increase in production costs. In addition, the solvent components are easily left in the electrodes, thereby affecting the battery's cycle performance, rate performance and other parameters.

[0004] Summary of the Invention

[0005] The electrode membrane provided by the present disclosure can significantly improve the structural strength and adhesion of the electrode membrane by limiting the composition of the electrode membrane and the aspect ratio of the fiber, ensuring that the components in the electrode membrane maintain a good bonding state. The electrode membrane can be directly applied to electrode sheets and can also ensure effective electron transmission. Applying the electrode membrane to batteries can significantly improve the cycle performance and rate performance of the batteries.

[0006] The present disclosure also provides an electrode sheet. Since it includes the above-mentioned electrode film, the electrode sheet has excellent conductivity and stability during the charge and discharge process. Applying the electrode sheet to a battery can improve the cycle performance and rate performance of the battery.

[0007] The present disclosure also provides a battery, which has excellent cycle performance and rate performance due to the inclusion of the above-mentioned electrode sheet.

[0008] In a first aspect of the present disclosure, an electrode membrane is provided, wherein the electrode membrane comprises fibers, wherein the ratio of the length to the diameter of the fibers is L1; wherein L1 is 10 to 1000, preferably, L1 is 20 to 500.

[0009] The electrode film as described above, wherein the cohesive force of the electrode film is N1, with a unit of N / m;

[0010] The L1 and N1 satisfy the following relationship: S = L1 / N1, and S is 0.5 to 40. Preferably, S is 1 to 36. More preferably, S is 2 to 10.

[0011] The electrode film as described above, wherein the porosity of the electrode film is ε%, and the cohesion of the electrode film is N1, with the unit of N / m;

[0012] X = N1 / ε, and X is 1 to 10. Preferably, X is 3 to 6.

[0013] The electrode film as described above, wherein N1 is 10 to 300 N / m. Preferably, N1 is 15 to 200 N / m;

[0014] ε is 20 to 45. Preferably, ε is 23 to 42.

[0015] The electrode film as described above, wherein the electrode film further includes an active material;

[0016] T = L1 / D1, T is 0.1 to 400. Preferably, T is 1 to 200. More preferably, T is 10 to 50, where D1 is the Dv50 of the active material, with the unit of μm.

[0017] The electrode film as described above, wherein D1 is 3 to 30 μm. Preferably, D1 is 5 to 15 μm.

[0018] The electrode film as described above, wherein the electrode film further includes an active material and carbon nanotubes;

[0019] The fibers and the carbon nanotubes are intertwined to form a composite network, and the active material is dispersed in the composite network.

[0020] The electrode film as described above, wherein the average diameter of the carbon nanotubes is D2, with the unit of nm, satisfying: 7 < L1 / D2 < 500. Preferably, 10 < L1 / D2 < 300.

[0021] The electrode film as described above, wherein D2 is 2 to 20 nm. Preferably, D2 is 3 to 6 nm.

[0022] In the second aspect of the present disclosure, there is provided an electrode sheet including the electrode film described in the first aspect; the electrode sheet further includes a current collector; the electrode film is disposed on at least one surface of the current collector.

[0023] The electrode sheet as described above, wherein the peeling force between the electrode film and the current collector is F1, with the unit of N; the thickness of the electrode film is H1, with the unit of μm; satisfying H1 / F1 ≥ 50%. Preferably, H1 / F1 ≥ 100%.

[0024] The electrode sheet as described above, wherein the thickness of the electrode film is H1, in μm; the porosity of the electrode film is ε%;

[0025] Satisfy 0.5

[0026] The electrode sheet as described above, wherein the electrode film includes an active material body,

[0027] The active material body includes LiCoO2, LiMn2O4, LiMnO2, LiNiO2, LiFePO4, LiMnPO4, LiCo x Ni 1-x O2、LiCo x Ni 1-x-y Al y At least one of O2, where 0≤x≤1, 0≤y≤1, or

[0028] The active material body includes artificial graphite, natural graphite, soft carbon, hard carbon, mesophase carbon microspheres, Si, SiO x 、Si-C、SiO x -At least one of C.

[0029] The electrode sheet as described above, wherein the electrode membrane includes fibers, and the fibers include at least one of fibrous polytetrafluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene propylene copolymer, polyvinyl pyrrolidone, polyethylene oxide, carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, hot melt adhesive, and polyethylene.

[0030] The electrode sheet as described above, wherein the electrode sheet further comprises a glue layer, and the glue layer is located between the current collector and the electrode film.

[0031] The electrode sheet as described above, wherein the glue layer comprises a binder and a conductive agent;

[0032] The adhesive includes at least one of polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), EVA hot melt adhesive, TPR hot melt adhesive, polyolefin hot melt adhesive, polyamide hot melt adhesive, polyester hot melt adhesive, polyethylene hot melt adhesive, polyesteramide hot melt adhesive, and / or

[0033] The conductive agent includes at least one of conductive carbon black, carbon nanotubes, and graphene.

[0034] A third aspect of the present disclosure provides a battery comprising the electrode sheet described in the second aspect.

[0035] The implementation of this disclosure has at least the following beneficial effects:

[0036] ​The electrode membrane provided by the present disclosure limits the composition of the electrode membrane and the aspect ratio L1 of the fiber, wherein the aspect ratio L1 of the fiber determines the degree of fiberization and affects the bonding force between the internal sublayers of the electrode membrane. By controlling L1 to 10 to 1000, it is possible to ensure that the network structure formed by the fibers has high strength and high stability, while ensuring that the electrode membrane has a good bonding state. The electrode membrane can be directly applied to electrode sheets without the need for additional solvents. In addition, it can ensure the effective transmission of electrons. Applying the electrode membrane to a battery can improve the powdering of the electrode membrane during the charge and discharge process, thereby improving the cycle performance and rate performance of the battery.

[0037] The electrode sheet provided by the present disclosure, because it includes the above-mentioned electrode film, has excellent electrochemical properties, and when applied to a battery, it helps to improve the electrochemical performance of the battery.

[0038] The battery provided by the present disclosure has excellent electrochemical performance, such as excellent cycle performance and rate performance, because it includes the above-mentioned electrode sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG1 is a cross-sectional SEM image of the second electrode film in Example 1 of the present disclosure;

[0040] FIG2 is a top view SEM image of the second electrode film in Example 1 of the present disclosure. DETAILED DESCRIPTION

[0041] To make the objectives, technical solutions, and advantages of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present disclosure.

[0042] According to a first aspect of the present disclosure, an electrode membrane is provided. The electrode membrane includes fibers, wherein the ratio of the length to the diameter of the fibers is L1, wherein L1 is 10 to 1000, and preferably, L1 is 20 to 500.

[0043] Electrode membranes are used to generate electrochemical reactions, thereby converting chemical energy into electrical energy.

[0044] The electrode membrane components disclosed herein include at least active material, conductive agent and binder, wherein the active material is used to generate electrochemical reaction, the conductive agent is used to improve the conductivity of the electrode membrane, and the binder is used to bond the active material and the conductive agent to form a complete electrode membrane.

[0045] Here, fiber refers to continuous or discontinuous filaments. In some embodiments, the fiber is a filamentous structure formed by fibrillating a binder. This disclosure does not limit the specific material of the fiber; specifically, the fiber can be a fibrillating binder commonly used in the art. For example, the binder can be at least one of polyvinylidene fluoride, acrylic resin, polytetrafluoroethylene, and styrene-butadiene rubber.

[0046] The fiber aspect ratio L1 is the fiber length divided by the fiber diameter in the electrode film. The fiber length refers to the fiber's dimension along its own extension direction, and the fiber diameter refers to the fiber's maximum dimension perpendicular to the extension direction.

[0047] Because fibers are formed by fibrillation of a binder, the fiber aspect ratio (L1) determines the degree of fibrillation of the binder. Since the binder acts as a bond between the active materials, the fiber aspect ratio (L1) also affects the adhesion between the components. The inventors believe that when L1 is between 10 and 1000, it can ensure good adhesion between the component particles in the electrode film, while also allowing the fibers in the electrode film to form a highly stable and mechanically strong network. This effectively improves the mechanical strength, electrical conductivity, structural uniformity, and thermal stability of the electrode film, thereby enhancing the cycling and rate performance of lithium-ion batteries.

[0048] In addition, the present disclosure regulates the degree of fiberization of the fibers by controlling the aspect ratio of the fibers, and can also take into account the uniformity, structural strength and stability of the bonding network formed by the fibers. If L1 is less than 10, the degree of fiberization of the binder is insufficient, and the molecular chains in the binder are not fully expanded, which easily leads to insufficient bonding strength of the bonding network formed by the fibers, making it difficult to bond other substances in the electrode membrane (such as active substances, conductive agents), and unable to form a film, resulting in a large internal resistance, which is not conducive to the construction of a conductive channel in the electrode membrane; if L1 is greater than 1000, the degree of fiberization of the binder is too high, and the stability of the bonding interface formed by the fibers is poor, which easily leads to uneven distribution of the components in the electrode membrane, which is not conducive to film formation, and holes are prone to appear on the obtained electrode membrane, the internal resistance increases, and the electrochemical reaction is uneven. By controlling L1 within the range of 10 to 1000, it is beneficial to take into account the enhancement of the structural strength and stability of the electrode membrane, and it can withstand greater stress and deformation.

[0049] Preferably, L1 is 20 to 500. By limiting L1 to the range of 20 to 500, it is beneficial to form more conductive channels and improve the transmission rate of lithium ions and electrons. At the same time, it helps to make the bonding network formed by the fibers in the electrode membrane evenly distributed, thereby filling the pores of the electrode membrane, reducing internal resistance, and reducing the unevenness of the electrochemical reaction.

[0050] In some embodiments, the cohesive force of the electrode film is N1, with units of N / m; L1 and N1 satisfy the following relationship: S=L1 / N1, and S is 0.5-40, wherein the cohesive force N1 of the electrode film refers to the cohesive force between the particles of each component in the electrode film, which directly affects the adhesion between the components. After research, the inventor believes that the value of S affects the bonding state between the particles, and the value of S affects the insertion and removal of lithium ions during the charging and discharging process of the battery. By limiting S to 0.5-40, it is possible to ensure that the particles in the electrode film have a good bonding state, which helps to improve the electrochemical performance. At the same time, it can also ensure the insertion and removal of lithium ions and avoid powdering of the electrode film. Preferably, S is 1-36, which can improve the mechanical strength of the electrode film while ensuring the bonding state of the electrode film.

[0051] More preferably, S is 2 to 10. By limiting S to the range of 2 to 10, a fiber network with high stability can be formed, which helps to improve the mechanical strength, conductivity, structural uniformity and thermal stability of the electrode sheet, thereby improving the electrochemical performance, mechanical performance and reliability of the battery.

[0052] The active material is the main material in the electrode membrane and is used for electrochemical reactions. In some embodiments, the electrode membrane also includes an active material; T = L1 / D1, T is 0.1 to 400, wherein D1 is the Dv50 of the active material, in μm. By limiting the ratio of the aspect ratio of the fiber to the Dv50 of the active material to within the range of 0.1 to 400, it is possible to ensure that the bonding network formed by the fiber has good coverage on the surface of the active material. During the battery cycle, the fiber can fill the cracks on the surface of the component particles in the electrode membrane, inhibiting the volume expansion of the active material, thereby enhancing the cycle stability of the battery. Preferably, T is 1 to 200, which can ensure that the bonding network formed by the fiber has good coverage on the surface of the active material while making the distribution of the bonding network formed by the fiber more uniform, thereby improving the overall mechanical strength of the electrode membrane.

[0053] More preferably, T is 10 to 50. By limiting T to the range of 10 to 50, a more uniform and stable fiber network can be formed, which helps to improve the structural uniformity and stability of the electrode membrane, thereby improving the cycle stability of the battery.

[0054] In the present disclosure, the electrode film also includes carbon nanotubes; fibers and carbon nanotubes are interwoven to form a composite network, and active materials are dispersed within the composite network. The carbon nanotubes and fibers interweave to form the composite network of the electrode film, which acts as a bond due to the presence of the fibers. The introduction of the carbon nanotubes increases both the density of the electrode film and the speed of free electrons, thereby improving the specific power and life of the battery.

[0055] In some embodiments, the average diameter of the carbon nanotubes is D2, in nanometers (nm), and satisfies: 7 < L1 / D2 < 500. By controlling the ratio of the fiber aspect ratio to the average diameter of the carbon nanotubes, it is beneficial to regulate the adhesiveness and conductivity of the composite network, thereby further improving the performance of the electrode film.

[0056] Preferably, 10 < L1 / D2 < 300. By further optimizing the value range of L1 / D2, both the active material and the conductive agent can be in the composite network formed by the fibers and the carbon nanotubes. While ensuring the density of the electrode film, it further improves the electronic conductivity of the electrode film, thereby contributing to improving the electrochemical performance of the battery.

[0057] Applying the electrode film of the present disclosure to a battery, the electrolyte is filled in the pores of the electrode film, and lithium ions are conducted through the electrolyte in the pores. The conduction characteristics of lithium ions are closely related to the porosity of the electrode film. In some embodiments, the porosity of the electrode film is ε%, X = N1 / ε, and X is 1 to 10. By controlling the ratio of the cohesive force of the electrode film to the porosity within the range of 1 to 10, it is beneficial to balance the improvement of the cycle performance and rate performance of the battery. If the ratio is less than 1, the conductive network of the electrode film is poor, the electronic conductivity decreases, the internal resistance of the battery increases, and it is more likely to cause gas generation and accumulation; if the ratio is greater than 10, the connection of each component in the electrode film is too tight, resulting in a decrease in the permeability of the electrolyte and deterioration of the ionic conductivity, affecting the rate performance and cycle performance of the battery.

[0058] Preferably, X is 3 to 6. By limiting X within the range of 3 to 6, it is possible to simultaneously shorten the migration paths of lithium ions and electrons, improve the transfer rates of lithium ions and electrons, thereby contributing to further improving the electrochemical performance of the battery.

[0059] The greater the cohesive force of the electrode film, the better the bonding state between the particles of each component in the electrode film. During the charge and discharge process, it is not easy to occur powder falling off as lithium ions are inserted and removed; however, as the cohesive force increases to a certain extent, it is difficult to disperse each component in the electrode film evenly, which is not conducive to improving the performance of the electrode film. In some embodiments, the cohesive force N1 of the electrode film is 10 to 300 N / m. By limiting N1 within the range of 10 to 300 N / m, it is possible to balance the bonding state and distribution uniformity between each component in the electrode film.

[0060] Preferably, N1 is 15 to 200 N / m. The cohesive force of the electrode film is related to the film-forming time of the electrode film. By limiting N1 within the range of 15 to 200 N / m, it helps to shorten the film-forming time of the electrode film and improve production efficiency.

[0061] Dv50 refers to the particle size corresponding to a cumulative volume fraction of 50%. The Dv50 of the active material is equal to D1, which is 3-30 μm. If the Dv50 of the active material is too large or too small, it will not form a good bond with the fiber. Limiting D1 to 3-30 μm helps maximize the capacity of the active material.

[0062] Preferably, D1 is 5 to 15 μm. The particle size of the active material is an important factor in the slurry process. By limiting D1 to the range of 5 to 15 μm, while ensuring the adhesion between the active material and the fiber, the stability of the slurry system formed by the active material can also be improved, thereby improving the uniformity of the components of the electrode film and maximizing the performance of each component in the electrode film. The average diameter of the carbon nanotubes will affect the structural stability of the electrode film. In some embodiments, the average diameter D2 of the carbon nanotubes is 2 to 20 nm. If the average diameter of the carbon nanotubes is less than 2 nm, problems such as cracks are likely to occur in the structure of the electrode film, and it is difficult to maintain sufficient strength. If the average diameter of the carbon nanotubes is greater than 20 nm, it is difficult to fully intertwine with the fibers, and the conductivity deteriorates. By limiting D2 to 2 to 20 nm, it is beneficial to maximize the reinforcing effect of the carbon nanotubes.

[0063] Preferably, D2 is 3 to 6 nm. By limiting D2 to the range of 3 to 6 nm, the carbon nanotubes can be embedded in the network formed by the fibers, promoting the distribution of the fibers and making the fiberization more uniform, thereby obtaining a highly stable composite network and helping to improve the structural uniformity of the electrode membrane.

[0064] A higher porosity in the electrode membrane corresponds to a higher volume fraction of the electrolyte phase, which in turn leads to more complete electrolyte infiltration and greater effective lithium ion conductivity. However, as the porosity of the electrode membrane increases beyond a certain point, the structural strength and stability of the electrode membrane deteriorate. In some embodiments, ε is between 20 and 45, meaning the electrode membrane porosity is between 20 and 45%. Limiting ε to this range helps balance lithium ion conductivity with the structural strength and stability of the electrode membrane.

[0065] Preferably, ε is 23 to 42, that is, the porosity of the electrode membrane is 23 to 42%. By preferably setting ε to 23 to 42, while taking into account the improvement of the structural strength and stability of the electrode membrane, it is also possible to achieve rapid transfer of lithium ions even in thicker electrode sheets, thereby improving the lithium ion conductivity of the thick electrode sheets.

[0066] The present disclosure does not limit the specific type of fiber. For example, the fiber includes at least one of fibrous polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene-tetrafluoroethylene copolymer (ETEF), fluorinated ethylene propylene copolymer (FEP), polyvinyl pyrrolidone (PVP), polyethylene oxide (PEO), carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyacrylic acid (PAA), hot melt adhesive, and polyethylene (PE).

[0067] In the present disclosure, the electrode film also includes a conductive agent. In this case, the fibers and carbon nanotubes are interwoven to form a composite network, and the active material and conductive agent are uniformly dispersed within the composite network. The conductive agent can be any commonly used conductive agent in the art. The conductive agent can be at least one of a zero-dimensional conductive agent, a two-dimensional conductive agent, and a three-dimensional conductive agent. Specifically, the conductive agent can be selected from, but not limited to, at least one of Super-P, conductive carbon black, and acetylene black.

[0068] The present disclosure does not limit the active material in the electrode film, and active materials commonly used in the art can be selected, for example, positive electrode active materials, negative electrode active materials. Specifically, the active material can be carbon material, metal platinum, silicon carbon material, silicon nitride, lithium iron phosphate material, positive electrode ternary material, silicon oxide material, lithium cobalt oxide, lithium manganese oxide, lithium titanate, etc. For example, the active material includes LiCoO2, LiMn2O4, LiMnO2, LiNiO2, LiFePO4, LiMnPO4, LiCo x Ni 1-x O2、LiCo x Ni 1-x-y Al y O2, wherein 0≤x≤1, 0≤y≤1, or the active material includes artificial graphite, natural graphite, soft carbon, hard carbon, mesophase carbon microspheres, Si, SiO x 、Si-C、SiO x -At least one of C

[0069] The present disclosure does not limit the preparation method of the above-mentioned electrode membrane, and it can be prepared by conventional methods in the field. For example, the active material, the conductive agent and the binder are mixed, and then an external high shear force is applied to fibrillate the binder to form a fiber network, which bonds the active material and the conductive agent, and forms an electrode membrane after extrusion. In one embodiment, the preparation method of the electrode membrane specifically includes the following steps: the conductive agent and the active material are subjected to a first premixing treatment, and then the raw material system of the binder is added and sequentially subjected to a second premixing treatment, a shearing treatment and a hot pressing treatment to obtain an electrode membrane. In the first premixing treatment, the rotation speed is 10 to 50 r / min, the temperature is 19 to 25°C, and the time is 5 to 20 min.

[0070] In the second premixing process, the rotation speed is 5 to 30 r / min, the temperature is 10 to 25° C., and the time is 3 to 20 min.

[0071] During the shearing process, the rotation speed is 3000-10000 r / min, the temperature is 30-60° C., and the time is 15-80 min.

[0072] The temperature of the hot pressing treatment is 80 to 150°C.

[0073] Specifically, during the shearing process, the molecular chains of the binder are fully expanded to form fibers, and the formed fibers can fully bond the active material and the conductive agent; finally, a hot pressing process is performed to obtain an electrode film.

[0074] The present disclosure does not impose any specific restrictions on the first premixing process and the second premixing process, as long as the above-mentioned rotation speed, temperature and time are met. In some embodiments, the first premixing process and the second premixing process can be performed in a blender.

[0075] The present disclosure does not impose any specific restrictions on the shearing process, as long as the above-mentioned rotation speed, temperature and time are met. In some embodiments, the shearing process can be performed in a shearing machine.

[0076] The present disclosure does not specifically limit the roller pressing process, and it can be a roller pressing process commonly used in the art, such as a hot pressing film forming process in an open mill.

[0077] In the preparation method of the electrode membrane disclosed in the present invention, the raw material system including the conductive agent, the binder and the active material is subjected to the first premixing treatment and the second premixing treatment through a specific process, which can achieve sufficient mixing of the conductive agent, the binder and the active material, and facilitate the subsequent shearing treatment; then the raw material system after the premixing treatment is sheared by a specific process, which can make the raw material system after the premixing treatment fully fibrillated, thereby obtaining the electrode membrane disclosed in the present invention.

[0078] A second aspect of the present disclosure provides an electrode sheet, comprising the electrode film provided in the first aspect.

[0079] The present disclosure does not limit the specific type of the electrode sheet. The electrode sheet may be an electrode of various electrochemical devices. For example, the electrode sheet may be a positive electrode sheet or a negative electrode sheet of a lithium-ion battery.

[0080] The electrode sheet further includes a current collector; the electrode film is disposed on at least one surface of the current collector.

[0081] In one embodiment, the positive electrode sheet includes a positive electrode current collector and an electrode film disposed on at least one surface of the positive electrode current collector. Specifically, the electrode film and at least one surface of the positive electrode current collector are subjected to a hot-pressing composite process to form the positive electrode sheet. In this case, the active material in the electrode film can be selected from, but not limited to, at least one of lithium cobalt oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium iron phosphate. The positive electrode current collector is aluminum foil.

[0082] In another embodiment, the negative electrode sheet includes a negative electrode current collector and an electrode film disposed on at least one surface of the negative electrode current collector. Specifically, the electrode film and at least one surface of the negative electrode current collector are hot-pressed to form the negative electrode sheet. The active material in the electrode film can be selected from at least one of graphite, silicon, and hard carbon, and the negative electrode current collector is copper foil.

[0083] Since the electrode sheet of the present disclosure includes the electrode film provided in the first aspect, the electrode sheet has excellent conductivity and stability during the charge and discharge process. Applying the electrode sheet to a battery can improve the cycle performance and rate performance of the battery.

[0084] By controlling the thickness of the electrode film and the peeling force relationship between the electrode film and the current collector, the electrode film can be prevented from falling off during cycling. In some embodiments, the peeling force between the electrode film and the current collector is F1; the thickness of the electrode film is H1, in μm; and H1 / F1 ≥ 50%. By setting H1 / F1 ≥ 50%, good adhesion between the current collector and the electrode film is ensured, facilitating electron transfer and preventing electrode film shedding during cycling. Preferably, H1 / F1 ≥ 100%.

[0085] In some embodiments, the thickness of the electrode film is H1, in μm; the porosity of the electrode film is ε%; and the 0.5

[0086] In some embodiments, the thickness H1 of the electrode film is 30-1000 μm.

[0087] ​In order to improve the adhesion between the electrode film and the current collector, in some embodiments, the electrode sheet further includes a glue layer, which is located between the current collector and the electrode film; the glue layer includes a binder and a conductive agent. The binder is used to improve the adhesion between the glue layer and the current collector and the adhesion between the glue layer and the electrode film, and the conductive agent is used to improve the conductivity of the glue layer. At the same time, the conductive agent can also increase the roughness of the glue layer and increase the specific surface area of ​​the glue layer, thereby further improving the adhesion and peeling force between the glue layer and the current collector and between the glue layer and the electrode film. The binder includes at least one of PVDF, SBR, EVA hot melt adhesive, TPR hot melt adhesive, polyolefin hot melt adhesive, polyamide hot melt adhesive, polyester hot melt adhesive, polyethylene hot melt adhesive, and polyesteramide hot melt adhesive, and / or the conductive agent includes at least one of conductive carbon black, carbon nanotubes, and graphene.

[0088] A third aspect of the present disclosure provides a battery, comprising the electrode sheet provided in the second aspect.

[0089] The battery can be prepared by a method comprising the following steps: stacking the positive electrode sheet obtained in the second aspect and the negative electrode sheet obtained in the second aspect to form an electrode assembly, with a separator disposed between the positive electrode sheet and the negative electrode sheet; placing the electrode assembly in an outer packaging, injecting an electrolyte into the outer packaging, and sealing the outer packaging to obtain a lithium-ion battery. The outer packaging can be an aluminum-plastic film.

[0090] The separator may be a separator commonly used in the art, for example, the separator may be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride; the electrolyte may be an electrolyte commonly used in the art, for example, the electrolyte includes at least an organic solvent and a lithium salt. The organic solvent may be selected from at least one of ethylene carbonate, butylene carbonate, propylene carbonate, ethyl methyl carbonate, vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, difluoroethylene carbonate, fluorodimethyl carbonate, dimethyl carbonate, diethyl carbonate, and dipropyl carbonate; the lithium salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), and lithium bis(fluorosulfonyl)imide (LiFSI).

[0091] The battery disclosed herein uses the aforementioned electrode film or electrode sheet, and therefore has excellent cycle performance and rate performance.

[0092] The present disclosure is further illustrated below by specific examples and comparative examples. Unless otherwise specified, the reagents, materials, and instruments used below are all conventional reagents, materials, and instruments, which are all commercially available, and the reagents and materials involved can also be synthesized by conventional synthesis methods.

[0093] Example 1

[0094] 1. Preparation of electrode membrane

[0095] Preparation of the first electrode film: The positive electrode active material and the conductive agent are mixed, and stirred at 25°C and 50 r / min for 20 minutes using a low-speed stirrer. Then, a binder is added, and stirred at 25°C and 30 r / min for 3 minutes. Then, the mixture is stirred at 55°C and 4000 r / min for 40 minutes to obtain a mixture. The mixture is hot-pressed into a film at 100°C using an open mill, and the first electrode film is obtained after being cut. The mass ratio of the positive electrode active material, the conductive agent, and the binder is 94.5:2.5:3.

[0096] Preparation of the second electrode film: 97 wt% graphite material and 1 wt% conductive carbon black were mixed and stirred in a low-speed mixer at 50 rpm at 25°C for 20 minutes. 2 wt% binder was then added and stirred at 30 rpm at 25°C for 3 minutes. The mixture was then stirred at 4000 rpm at 30°C for 40 minutes. The mixture was then hot-pressed at 100°C on an open mill to form a film with a thickness of 100 μm. SEM images of the second electrode film are shown in Figures 1 and 2.

[0097] 2. Preparation of electrode sheets

[0098] Preparation of positive electrode sheet: The first electrode film and aluminum foil are hot-pressed and laminated at 80°C and 15t, and then cut into pieces to obtain the positive electrode sheet.

[0099] Preparation of negative electrode sheet: The second electrode film and copper foil are hot-pressed and laminated at 80°C and 15t, and then cut into pieces to obtain the negative electrode sheet.

[0100] 3. Preparation of batteries

[0101] The positive electrode sheet, separator and negative electrode sheet are stacked in sequence and wound to obtain a bare cell, which is then placed in an outer packaging aluminum-plastic film. The electrolyte is injected into the bare cell, and after vacuum packaging, standing, formation, secondary sealing, sorting, shaping and testing processes, a soft-pack lithium-ion battery is obtained. The electrolyte is purchased from Xinzhoubang LBC450A23 and the separator is purchased from Asahi Kasei ND522.

[0102] Example 2

[0103] The preparation process was basically the same as that of Example 1, except that in the preparation process of the second electrode membrane, "stirring at a fiberizing speed of 4000 r / min for 40 min" was replaced with "stirring at a fiberizing speed of 8000 r / min for 40 min". Other conditions remained unchanged, and the second electrode membrane of this embodiment was obtained.

[0104] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0105] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0106] Example 3

[0107] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the second electrode membrane, "stirring at a fiberizing speed of 4000 r / min for 40 min" is replaced by "stirring at a fiberizing speed of 10000 r / min for 40 min", and other conditions remain unchanged, to obtain the second electrode membrane of this embodiment;

[0108] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0109] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0110] Example 4

[0111] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the second electrode film, "97wt% graphite material, 1wt% conductive agent carbon black, 2wt% binder" is replaced by "95.5wt% graphite material, 1.5wt% conductive agent carbon black, 3wt% binder"; "stirring at a fiberizing speed of 4000 r / min for 40 min" is replaced by "stirring at a fiberizing speed of 10000 r / min for 40 min", and other conditions remain unchanged to obtain the second electrode film of this embodiment;

[0112] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0113] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0114] Example 5

[0115] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the second electrode film, "97wt% graphite material, 1wt% conductive agent carbon black, 2wt% binder" is replaced by "95.5wt% graphite material, 1.5wt% conductive agent carbon black, 3wt% binder"; "stirring at a fiberizing speed of 4000 r / min for 40 min" is replaced by "stirring at a fiberizing speed of 12000 r / min for 40 min", and other conditions remain unchanged to obtain the second electrode film of this embodiment;

[0116] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0117] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0118] Example 6

[0119] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the second electrode film, "97wt% graphite material, 1wt% carbon black, 2wt% binder" is replaced by "95.5wt% graphite material, 0.75wt% carbon black, 0.75wt% carbon nanotubes, 3wt% binder"; "stirring at a fiberizing speed of 4000 r / min for 40 min" is replaced by "stirring at a fiberizing speed of 12000 r / min for 40 min", and other conditions remain unchanged to obtain the second electrode film of this embodiment;

[0120] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0121] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0122] Example 7

[0123] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the second electrode film, "97wt% graphite material, 1wt% conductive agent carbon black, 2wt% binder" is replaced by "93.5wt% graphite material, 1.5wt% conductive agent carbon black, 5wt% binder"; "stirring at a fiberizing speed of 4000 r / min for 40 min" is replaced by "stirring at a fiberizing speed of 12000 r / min for 40 min", and other conditions remain unchanged to obtain the second electrode film of this embodiment;

[0124] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0125] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0126] Example 8

[0127] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the second electrode film, "97wt% graphite material, 1wt% conductive agent carbon black, 2wt% binder" is replaced by "44wt% graphite material, 50wt% silicon material, 1.5wt% carbon black, 1.5wt% carbon nanotubes, 3wt% binder"; "stirring at a fiberizing speed of 4000r / min for 40min" is replaced by "stirring at a fiberizing speed of 12000r / min for 40min", and other conditions remain unchanged to obtain the second electrode film of this embodiment;

[0128] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0129] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0130] Example 9

[0131] The preparation process is basically the same as that of Example 1, except that: in the preparation process of the second electrode film, "97wt% graphite material, 1wt% conductive agent carbon black, 2wt% binder" is replaced with "92wt% silicon material, 2.5wt% carbon black, 2.5wt% carbon nanotubes, 3wt% binder"; "stirring at a fiberizing speed of 4000 r / min for 40 min" is replaced with "stirring at a fiberizing speed of 12000 r / min for 40 min", and other conditions remain unchanged to obtain the second electrode film of this embodiment;

[0132] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0133] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0134] Example 10

[0135] The preparation process is basically the same as that of Example 1, except that: the preparation process of the second electrode film of this embodiment is as follows: 95.5wt% of graphite material, 0.75wt% of carbon black, and 0.75wt% of carbon nanotubes are mixed, and stirred at 20°C and 50r / min for 20 minutes using a low-speed stirrer, and then 3wt% of a binder is added, and stirred at 20°C and 30r / min for 3 minutes, and then stirred at 30°C and 12000r / min for 40 minutes to obtain a mixture; the mixture is hot-pressed at 100°C using an open mill to form a film to obtain a second electrode film with a thickness of 90μm;

[0136] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0137] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0138] Example 11

[0139] The preparation process was basically the same as that of Example 10, except that in the preparation process of the second electrode membrane, "stirring at 30°C and a fiberizing speed of 12000 r / min for 40 min" was replaced with "stirring at 40°C and a fiberizing speed of 12000 r / min for 40 min". Other conditions remained unchanged, and the second electrode membrane of this embodiment was obtained.

[0140] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0141] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0142] Example 12

[0143] The preparation process was basically the same as that of Example 10, except that in the preparation process of the second electrode membrane, "stirring at 30° C. and a fiberizing speed of 12,000 r / min for 40 min" was replaced with "stirring at 50° C. and a fiberizing speed of 12,000 r / min for 40 min". Other conditions remained unchanged, thereby obtaining the second electrode membrane of this embodiment.

[0144] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0145] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0146] Example 13

[0147] The preparation process was basically the same as that of Example 10, except that in the preparation process of the second electrode membrane, "stirring at 30°C and a fiberizing speed of 12000 r / min for 40 min" was replaced with "stirring at 60°C and a fiberizing speed of 12000 r / min for 40 min". Other conditions remained unchanged, thereby obtaining the second electrode membrane of this embodiment.

[0148] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0149] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0150] Example 14

[0151] The preparation process was basically the same as that of Example 10, except that in the preparation process of the second electrode membrane, "stirring at 30°C and a fiberizing speed of 12,000 r / min for 40 min" was replaced with "stirring at 50°C and a fiberizing speed of 12,000 r / min for 40 min". Other conditions remained unchanged, and a second electrode membrane with a thickness of 30 μm in this example was prepared.

[0152] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0153] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0154] Example 15

[0155] The preparation process was basically the same as that of Example 10, except that in the preparation process of the second electrode membrane, "stirring at 30°C and a fiberizing speed of 12,000 r / min for 40 min" was replaced with "stirring at 50°C and a fiberizing speed of 12,000 r / min for 40 min". Other conditions remained unchanged, and a second electrode membrane with a thickness of 60 μm was prepared in this example.

[0156] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0157] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0158] Example 16

[0159] The preparation process was basically the same as that of Example 10, except that in the preparation process of the second electrode membrane, "stirring at 30°C and a fiberizing speed of 12,000 r / min for 40 min" was replaced with "stirring at 50°C and a fiberizing speed of 12,000 r / min for 40 min". Other conditions remained unchanged, and a second electrode membrane with a thickness of 150 μm in this example was prepared.

[0160] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0161] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0162] Example 17

[0163] The preparation process was basically the same as that of Example 10, except that in the preparation process of the second electrode membrane, "stirring at 30°C and a fiberizing speed of 12,000 r / min for 40 min" was replaced with "stirring at 50°C and a fiberizing speed of 12,000 r / min for 40 min". Other conditions remained unchanged, and a second electrode membrane with a thickness of 200 μm in this example was prepared.

[0164] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0165] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0166] Example 18

[0167] The preparation process was basically the same as that of Example 10, except that in the preparation process of the second electrode membrane, "stirring at 30°C and a fiberizing speed of 12,000 r / min for 40 min" was replaced with "stirring at 50°C and a fiberizing speed of 12,000 r / min for 40 min". Other conditions remained unchanged, and a second electrode membrane with a thickness of 250 μm in this example was prepared.

[0168] In the preparation of the negative electrode sheet, the second electrode film is replaced with the second electrode film of this embodiment to obtain the negative electrode sheet of this embodiment;

[0169] During the preparation of the battery, the negative electrode sheet is replaced with the negative electrode sheet of this embodiment.

[0170] Comparative Example 1

[0171] 1. Preparation of electrode sheets

[0172] 1. Preparation of positive electrode

[0173] Lithium cobalt oxide (LiCoO2), conductive agent SP, PVDF and solvent NMP are evenly mixed to obtain a positive electrode slurry with a solid content of 76%. The obtained positive electrode slurry is evenly coated on the surface of the positive electrode collector, and the positive electrode sheet is obtained after drying, rolling and cutting.

[0174] 2. Preparation of negative electrode sheet

[0175] 97% graphite, 1% carbon black and 2% binder are uniformly mixed, stirred at 25°C and 30 r / min for 30 minutes using a low-speed stirrer, and then stirred at 30°C and 8000 r / min for 40 minutes to obtain a mixture; the mixture is hot-pressed into a film at 100°C using an open mill to obtain a negative electrode film with a thickness of 100 μm, the negative electrode film is hot-pressed with copper foil at 80°C and 15t, and cut into pieces to obtain a negative electrode sheet.

[0176] 2. Preparation of batteries

[0177] The positive electrode sheet, separator and negative electrode sheet are stacked in sequence and wound to obtain a bare cell, which is then placed in an outer packaging aluminum-plastic film. The electrolyte is injected into the bare cell, and after vacuum packaging, standing, formation, secondary sealing, sorting, shaping and testing processes, a soft-pack lithium-ion battery is obtained. The electrolyte is purchased from Xinzhoubang LBC450A23 and the separator is purchased from Asahi Kasei ND522.

[0178] Test example

[0179] (1) SEM test

[0180] The positive and negative electrode sheets were cut into 0.5 cm × 0.5 cm test samples. The microscopic morphology of the first electrode film on the positive electrode sheet and the second electrode film on the negative electrode sheet were obtained by scanning electron microscopy, and the aspect ratio of the fibers in the electrode films was obtained.

[0181] (2) Particle size test

[0182] A laser particle size analyzer is used for testing. Using the principle of laser diffraction, the particle size distribution is calculated by measuring the scattering angle of laser light from the particles. During testing, at least 0.2g of active material sample is scraped from the electrode sheet and evenly dispersed in the solution. The sample is then measured using the laser particle size analyzer to obtain the particle size distribution data (Dv50).

[0183] (3) Scanning probe microscope test

[0184] The average diameter D2 of carbon nanotubes was measured using a scanning probe microscope according to the national standard GB / T 26826-2011.

[0185] (4) Micrometer test

[0186] The thickness of the pole piece at different positions is tested with a micrometer, and the average value of multiple points is taken to obtain the actual thickness H1 of the pole piece.

[0187] (2) Porosity test

[0188] The positive and negative electrodes were cut into rectangular blocks of the same size. Twenty samples were tested in each embodiment, and the volume of each sample was about 2 cm. 3 .

[0189] The porosity of the first electrode membrane and the second electrode membrane was tested according to the standard "GB / T24586-2009 Determination of apparent density, true density and porosity of iron ore", and the test gas was helium.

[0190] (3) Peel force test

[0191] The positive electrode sheet and the negative electrode sheet were cut into test samples with a length of 100 mm and a width of 25 mm respectively.

[0192] Take a stainless steel plate with a length of 200 mm and a width of 50 mm, and fit one side of the stainless steel to one side of a double-sided tape (with a length of 100 mm and a width of 26 mm), and fit one side of the test sample to the other side of the double-sided tape, and use a pressure roller to roll back and forth on the surface of the other side of the test sample three times; bend one end of the test sample 180 degrees, and peel off the electrode film and the current collector of the test sample by 25 mm along the length direction. Fix the test sample on the testing machine so that the peeling surface is consistent with the force line of the testing machine (keep the pulling direction of the testing machine parallel to the length direction of the electrode sheet). The testing machine continuously peels at a speed of 200 mm / min to obtain a peeling force curve; take the force F corresponding to the plateau on the peeling force curve, according to the peeling force F1 = F / width of the test sample (the unit of measurement of F: N / m).

[0193] (4) Cohesion test

[0194] The positive electrode sheet and the negative electrode sheet were cut into test samples with a length of 100 mm and a width of 15 mm respectively. Take a stainless steel plate with a length of 200 mm and a width of 50 mm, and adhere one side of the stainless steel to a double-sided tape (one side with a length of 100 mm and a width of 16 mm), adhere one side of the test sample to the other side of the double-sided tape, and use a pressure roller to roll back and forth on the surface of the other side of the test sample three times; then, apply low-viscosity green glue (the bonding strength of the low-viscosity green glue is 350±20g / 25mm) to the surface of the electrode membrane of the test sample. Bend one end of the test sample 180 degrees, peel the electrode membrane and the green glue 25mm apart along the length direction, and fix the test sample on the testing machine so that the peeling surface is consistent with the force line of the testing machine (keep the pulling direction of the testing machine parallel to the length direction of the electrode sheet). The testing machine continuously peels at a speed of 200 mm / min to obtain a peel force curve. Take the peel force M corresponding to the plateau on the peel force curve, and the cohesive force N1 of the electrode membrane in the test sample = M / width of the test sample (N1 is measured in N / m).

[0195] (5) Resistance test of electrode film

[0196] The electrode membrane was cut into a rectangular size of 5cm×10cm and placed between the two electrodes of the membrane resistance meter. The test pressure was set to 0.2~0.4MPa and the holding time was 1~2s on the membrane resistance meter. The test was started to obtain the resistance, pressure and other data of the electrode membrane. Ten positions were selected for testing on each electrode membrane.

[0197] (6) EIS test

[0198] The three-electrode battery with copper wire plated was connected to the electrochemical workstation for testing. The test frequency range was 70mHz to 20kHz and the amplitude was 5mV. After collecting the data, the data was analyzed through the impedance complex plane diagram to obtain the electron transfer resistance (Rct) on the electrode surface.

[0199] (7) Cycle performance and rate performance test

[0200] Rate performance test: At 20±5°C, the battery is charged at 3C and then discharged at 3C. The 3C discharge capacity retention rate (%) is calculated as 3C discharge capacity / charge capacity × 100%.

[0201] Cycling performance test: At 20±5°C, the battery is charged at a constant current and constant voltage of 3C, then discharged at 3C for 500 cycles. The capacity after 500 cycles is calculated as a percentage of the initial capacity, i.e., the capacity retention rate (%) after 3C cycles 500T.

[0202] The test results are shown in Tables 1 to 3.

[0203] Table 1

[0204] Table 2

[0205] Table 3

[0206] According to Tables 1 to 3, the electrode membrane provided by the present invention can ensure that the network structure formed by the fibers has high strength and high stability by controlling L1 within the range of 10 to 1000, while ensuring that the inside of the electrode membrane has a good bonding state, which helps to reduce the resistance of the electrode membrane. When the electrode membrane is applied to an electrode sheet, it can significantly reduce the electron transfer resistance on the surface of the electrode sheet, which is helpful for electron transmission. When applied to a battery, it can improve the powder loss of the electrode membrane during the charge and discharge process, thereby improving the cycle performance and rate performance of the battery, especially achieving a 3C discharge capacity retention rate of ≥66% and a capacity retention rate of 73.5% or more after 500 cycles of 3C charge and discharge cycles.

[0207] The above describes in detail the preferred embodiments and experimental verifications of the present disclosure. It should be understood that ordinary technicians in this field can make many modifications and variations based on the concepts of this disclosure without creative effort. Therefore, any technical solutions that can be obtained by those skilled in the art based on the concepts of this disclosure through logical analysis, reasoning, or limited experimentation on the basis of existing technologies should be within the scope of protection of this disclosure.

Claims

1. An electrode film, characterized in that, The electrode film includes fibers, and the ratio of the length to the diameter of the fibers is L1; wherein, L1 is from 10 to 1000, preferably, L1 is from 20 to 500.

2. The electrode film according to claim 1, characterized in that, The cohesive force of the electrode film is N1, with the unit of N / m; The L1 and N1 satisfy the following relationship: S = L1 / N1, and S is from 0.5 to 40, preferably, S is from 1 to 36, more preferably, S is from 2 to 10.

3. The electrode film according to claim 1, wherein The porosity of the electrode film is ε%, and the cohesive force of the electrode film is N1, with the unit of N / m; X = N1 / ε, and X is from 1 to 10, preferably, X is from 3 to 6.

4. The electrode film according to claim 3, wherein N1 is from 10 to 300 N / m, preferably, N1 is from 15 to 200 N / m; ε is from 20 to 45, preferably, ε is from 23 to 42.

5. The electrode film according to claim 1, characterized in that, The electrode film further includes an active material; T = L1 / D1, T is from 0.1 to 400, preferably, T is from 1 to 200, more preferably, T is from 10 to 50, wherein, D1 is the Dv50 of the active material, with the unit of μm.

6. The electrode film according to claim 5, characterized in that, D1 is from 3 to 30 μm, preferably, D1 is from 5 to 15 μm.

7. The electrode film according to claim 1, wherein The electrode film further includes an active material and carbon nanotubes; The fibers and the carbon nanotubes are intertwined to form a composite network, and the active material is dispersed in the composite network.

8. The electrode film according to claim 7, characterized in that, The average diameter of the carbon nanotubes is D2, with the unit of nm, satisfying: 7 < L1 / D2 < 500, preferably, 10 < L1 / D2 < 300.

9. The electrode film according to claim 8, wherein D2 is from 2 to 20 nm, preferably, D2 is from 3 to 6 nm.

10. An electrode sheet, characterized in that, Including the electrode film according to any one of claims 1-9; the electrode sheet further includes a current collector; the electrode film is disposed on at least one surface of the current collector.

11. The electrode sheet according to claim 10, characterized in that, The peeling force between the electrode film and the current collector is F1, with the unit of N; the thickness of the electrode film is H1, with the unit of μm; satisfying H1 / F1 ≥ 50%, preferably, H1 / F1 ≥ 100%.

12. The electrode sheet according to claim 10 or 11, characterized in that, The thickness of the electrode film is H1, with the unit of μm; the porosity of the electrode film is ε%; Satisfying 0.5 < H1 / ε < 10, preferably, 1 < H1 / ε < 7.

13. The electrode sheet according to claim 10, wherein The electrode film includes an active material, The active material includes at least one of LiCoO2, LiMn2O4, LiMnO2, LiNiO2, LiFePO4, LiMnPO4, LiCo x Ni 1-x O2, LiCo x Ni 1-x-y Al y O2, where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, or, The active material includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon, mesocarbon microbeads, Si, SiO x , Si-C, SiO x -C.

14. The electrode sheet according to claim 10, wherein The electrode film includes fibers, and the fibers include at least one of fibrous polytetrafluoroethylene, polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene propylene copolymer, polyvinylpyrrolidone, polyethylene oxide, carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, hot melt adhesive, polyethylene.

15. The electrode sheet according to claim 10, wherein, The electrode sheet further includes an adhesive layer, and the adhesive layer is located between the current collector and the electrode film.

16. The electrode sheet according to claim 15, characterized in that, The adhesive layer includes a binder and a conductive agent; The binder includes at least one of polyvinylidene fluoride, styrene-butadiene rubber, EVA-based hot melt adhesive, TPR-based hot melt adhesive, polyolefin-based hot melt adhesive, polyamide-based hot melt adhesive, polyester-based hot melt adhesive, polyethylene-based hot melt adhesive, polyester amide-based hot melt adhesive, and / or The conductive agent includes at least one of conductive carbon black, carbon nanotubes, graphene.

17. A battery, characterized in that, Including the electrode sheet according to any one of claims 10-16.

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