Composite electrode sheet, method for manufacturing composite electrode sheet, battery, battery pack, and electric device

Abstract

The embodiment of the present application provides a composite pole piece, a composite pole piece preparation method, a battery, a battery pack and an electrical equipment. The composite pole piece has a first direction and comprises: a current collector; an active material layer, which is arranged at intervals with the current collector along the first direction; a stress buffer layer, which is connected with the current collector on one side along the first direction and connected with the active material layer on the other side; wherein the stress buffer layer comprises a support structure, which is used to improve the elastic modulus of the stress buffer layer. The composite pole piece provided by the embodiment of the present application can effectively resist the stress generated by the volume change of the active material layer, reduce the occurrence of problems such as the collapse of the pole piece structure, and improve the performance and cycle life of the battery by setting the stress buffer layer and the support structure which can improve the elastic modulus of the stress buffer layer and the strength of the composite pole piece.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to a composite electrode, a method for preparing the composite electrode, a battery, a battery pack, and electrical equipment. Background Technology

[0002] Rechargeable batteries, such as lithium-ion batteries, are widely used in electric vehicles, aerospace, and other fields due to their high energy efficiency and environmental friendliness. Electrodes, as a crucial component of the battery, significantly impact its performance.

[0003] In related technologies, electrodes typically consist of stacked current collectors and active material layers. During charging and discharging, the active material layer expands, causing its volume to increase. This can lead to problems such as electrode structure collapse, which in turn affects battery performance and cycle life. Summary of the Invention

[0004] This application aims to provide a composite electrode, a method for preparing a composite electrode, a battery, a battery pack, and an electrical device to solve the problem that existing electrodes, during charging and discharging, will cause the active material layer to expand, resulting in an increase in their own volume, which may lead to the collapse of the electrode structure and thus affect the performance and cycle life of the battery.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows: In a first aspect, this application discloses a composite electrode having a first orientation, the composite electrode comprising: current collector; An active material layer is provided, wherein the active material layer and the current collector are spaced apart along the first direction; A stress buffer layer, wherein one side of the stress buffer layer along the first direction is connected to the current collector, and the other side is connected to the active material layer; The stress buffer layer includes a support structure, which is used to improve the elastic modulus of the stress buffer layer.

[0006] Optionally, the support structure is any one of carbon fiber, PVDF-HFP composite doped with conductive carbon nanotubes / graphene, or SEBS copolymer.

[0007] Optionally, the stress buffer layer further includes an active material and an adhesive, wherein the active material, the adhesive, and the support structure are mixed and distributed, the content of the active material is 85wt%~90wt%, the content of the support structure is 2wt%~10wt%, and the content of the adhesive is 2wt%~10wt%.

[0008] Optionally, the elastic modulus of the stress buffer layer is 5 GPa-50 GPa.

[0009] Optionally, the thickness of the stress buffer layer along the first direction is 5μm-30μm.

[0010] Optionally, the porosity of the stress buffer layer is 30%-60%.

[0011] Optionally, the active material layer includes at least a mixture of active material, conductive agent, elastic structure and adhesive, wherein the elastic structure is used to form a cavity structure within the active material layer.

[0012] Optionally, the composite electrode further includes an electrolyte layer connected to the side of the active material layer away from the stress buffer layer.

[0013] Optionally, the thickness of the electrolyte layer along the first direction is 2μm-5μm.

[0014] Secondly, this application also provides a method for preparing a composite electrode, the method being used to prepare a composite electrode as described in any of the above claims, the method comprising: Provide current collectors; A stress buffer layer slurry is prepared, wherein the stress buffer layer slurry includes supporting structural raw materials; Preparation of active substance layer slurry; The stress buffer layer slurry is applied to the current collector to form a stress buffer layer; The active material layer slurry is applied onto the stress buffer layer to form the active material layer.

[0015] Optionally, the method for preparing the composite electrode further includes: preparing an electrolyte layer slurry; The electrolyte layer slurry is coated onto the active material layer to form the electrolyte layer.

[0016] Thirdly, this application also discloses a battery comprising: the composite electrode as described in any of the preceding claims.

[0017] Fourthly, this application also discloses a battery pack, the battery pack comprising the battery described above.

[0018] Fifthly, this application also discloses an electrical device, which includes: a battery as described above or a battery pack as described above.

[0019] In this embodiment, a stress buffer layer is provided between the active material layer and the current collector. The stress buffer layer includes a support structure, which can improve the elastic modulus of the stress buffer layer and increase the strength of the composite electrode. This can effectively resist the stress caused by the volume change of the active material layer, reduce the occurrence of problems such as electrode structure collapse, and improve the performance and cycle life of the battery.

[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0021] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is one of the structural schematic diagrams of a composite electrode provided in the embodiments of this application; Figure 2 This is a second schematic diagram of the structure of a composite electrode provided in the embodiments of this application.

[0022] Figure label: 11-Current collector; 12-Active material layer; 13-Stress buffer layer; 14-Electrolyte layer; Z-First direction. Detailed Implementation

[0023] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0024] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0025] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0026] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0027] Rechargeable batteries, such as lithium-ion batteries, are widely used in electric vehicles, aerospace, and other fields due to their high energy efficiency and environmental friendliness. Electrodes, as a crucial component of the battery, significantly impact its performance.

[0028] In related technologies, electrodes typically consist of stacked current collectors and active material layers. During charging and discharging, the active material layer expands, causing its volume to increase and generating stress. This stress may lead to problems such as electrode structure collapse, thereby affecting battery performance and cycle life.

[0029] This application provides a composite electrode, which will be described in detail below with reference to the accompanying drawings.

[0030] Example 1 Reference Figures 1 to 2 This application provides a composite electrode with a first direction Z. The composite electrode includes: a current collector 11; an active material layer 12, which is spaced apart from the current collector 11 along the first direction Z; and a stress buffer layer 13, which is connected to the current collector 11 on one side along the first direction Z and to the active material layer 12 on the other side. The stress buffer layer 13 includes a support structure for improving the elastic modulus of the stress buffer layer 13.

[0031] Specifically, such as Figure 1 and Figure 2As shown, the first direction Z is the Z-axis direction shown in the figure, where the first direction Z can be the thickness direction of the composite electrode.

[0032] Specifically, the current collector 11 is used to collect the current generated by the active material layer 12 to form a larger current for output. It can be a rectangular sheet structure, and the current collector 11 is made of a conductive material, such as copper foil or aluminum foil. This application does not specifically limit this. For example, the composite electrode can be a positive electrode or a negative electrode. The current collector 11 of the positive electrode can be aluminum foil, and the current collector 11 of the negative electrode can be copper foil.

[0033] The active material layer 12 is used to store and convert charges through redox reactions or ion adsorption or desorption, providing a current source that can be collected for the current collector 11.

[0034] The current collector 11 includes a first surface and a second surface disposed opposite to each other along a first direction Z, such as Figure 1 As shown, the active material layer 12 can be a single layer, which can be spaced apart from the first surface or the second surface along the first direction Z. In this case, the stress buffer layer 13 is a single layer, and the two surfaces of the stress buffer layer 13 arranged along the first direction Z are respectively connected to the first surface and the active material layer 12.

[0035] like Figure 2 As shown, the active material layer 12 can also be two layers. One active material layer 12 is spaced apart from the first surface along the first direction Z, and the other active material layer 12 is spaced apart from the second surface along the first direction Z. In this case, the stress buffer layer 13 also has two layers. One stress buffer layer 13 has two surfaces along the first direction Z that are connected to the first surface and the active material layer 12, respectively. The other stress buffer layer 13 has two surfaces along the first direction Z that are connected to the second surface and the other active material layer 12, respectively. The stress buffer layer 13 can be connected between the current collector 11 and the active material layer 12 through a coating process.

[0036] The stress buffer layer 13 includes a support structure distributed within it. This support structure enhances the elastic modulus of the stress buffer layer 13. The elastic modulus is an indicator of how easily a material undergoes elastic deformation; a higher value indicates greater stress required for elastic deformation, meaning greater material stiffness and less elastic deformation under stress. Therefore, increasing the elastic modulus of the stress buffer layer 13 improves the strength of the composite electrode. Furthermore, the support structure enhances the conductivity of the stress buffer layer 13, facilitating electron transport between the current collector 11 and the active material layer 12, forming a conductive path, and increasing electronic conductivity.

[0037] Table 1

[0038] In Table 1 above, the stress buffer layer 13 does not include the supporting structure in the comparative example; in Example 1, the stress buffer layer 13 includes the supporting structure. As shown in Table 1 above, when the composite electrode is a positive electrode, the elastic moduli of the three samples in Example 1 are 1.92 GPa, 1.98 GPa, and 2.03 GPa, respectively, which are significantly higher than the corresponding samples in the comparative example (1.53 GPa, 1.59 GPa, and 1.46 GPa). When the composite electrode is a negative electrode, the elastic moduli of the three samples in Example 1 are 0.84 GPa, 0.87 GPa, and 0.88 GPa, which are also much higher than the comparative example (0.58 GPa, 0.61 GPa, and 0.61 GPa). This indicates that the supporting structure can improve the elastic modulus of the stress buffer layer 13, thereby enhancing the overall strength of the composite electrode.

[0039] In this embodiment, a stress buffer layer 13 is provided between the active material layer 12 and the current collector 11. The stress buffer layer 13 includes a support structure, which can improve the elastic modulus of the stress buffer layer 13 and improve the strength of the composite electrode. This can effectively resist the stress caused by the volume change of the active material layer 12, reduce the occurrence of problems such as electrode structure collapse, and improve the performance and cycle life of the battery.

[0040] Example 2 Optionally, the support structure can be any one of carbon fiber, PVDF-HFP composite doped with conductive carbon nanotubes / graphene, or SEBS copolymer.

[0041] Specifically, carbon fiber is a high-strength, high-modulus fiber material with a high carbon content. It possesses high strength and high modulus, and its elastic modulus can be significantly improved in stress buffer layer 13. The PVDF-HFP composite doped with conductive carbon nanotubes / graphene refers to a composite formed by doping conductive carbon nanotubes and graphene into polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) copolymer. Due to the excellent conductivity and mechanical properties of conductive carbon nanotubes and graphene, and the good flexibility and chemical stability of PVDF-HFP, the combination of these three materials allows stress buffer layer 13 to possess both high elastic modulus and good conductivity and stability. SEBS copolymer is a copolymer obtained by hydrogenating styrene-butadiene-styrene block copolymer (SBS). It possesses good elasticity, aging resistance, and processability, and its elastic modulus can be improved and its overall performance enhanced in stress buffer layer 13.

[0042] Example 3 Optionally, the stress buffer layer 13 further includes an active material, an adhesive, and a supporting structure, which are mixed and distributed together. The active material content is 85wt%~90wt%, the supporting structure content is 2wt%~10wt%, and the adhesive content is 2wt%~10wt%.

[0043] Specifically, the active material provides electrochemical activity during the battery's charging and discharging process, enabling energy storage and conversion. For the positive electrode, the active material may include, but is not limited to, lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. The lithium phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4, abbreviated as LFP), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. For the negative electrode, the active material may include, but is not limited to, at least one of artificial graphite, natural graphite, mesophase carbon microspheres, hard carbon, soft carbon, silicon, silicon oxide, silicon carbon, and silicon alloys. This application does not specifically limit these aspects.

[0044] The adhesive may include one or more of polyvinylidene fluoride (PVDF), acrylic-modified PVDF, polyacrylate polymers, polyacrylic acid, polypropylene salts, polyimide, styrene-butadiene rubber, and styrene-acrylic rubber, and this application does not specifically limit the specific types. The adhesive is used to ensure good bonding between the components.

[0045] For example, the content of the active material can be 85wt%, 86wt%, 87wt%, 88wt%, 89wt%, 90wt%, etc.; the content of the supporting structure can be 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, etc.; and the content of the adhesive can be 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, etc. This application does not specifically limit these aspects. In some embodiments, the stress buffer layer 13 may also include conductive agents, additives, and other components to improve the conductivity, stability, and other properties of the stress buffer layer 13.

[0046] In this embodiment, if the active material content is too low, the energy density of the battery will decrease; if the content is too high, it may affect the performance of other properties of the stress buffer layer 13. When the active material content is between 85wt% and 90wt%, the battery can have sufficient electrochemical activity to achieve energy storage and conversion. If the supporting structure content is too low, the improvement effect on elastic modulus and conductivity is not significant; while if the content is too high, it may affect the uniform distribution of the components in the stress buffer layer 13. When the supporting structure content is between 2wt% and 10wt%, it can effectively improve the elastic modulus and conductivity of the stress buffer layer 13, while also ensuring the uniform distribution of other components. If the binder content is too low, the bonding force between the components will be insufficient, which may lead to instability in the structure of the stress buffer layer 13; if the content is too high, it may reduce the conductivity and other properties of the stress buffer layer 13. When the binder content is between 2wt% and 10wt%, it can ensure good bonding force between the components without having a significant negative impact on other properties.

[0047] Example 4 Optionally, the elastic modulus of the stress buffer layer 13 is 5 GPa-50 GPa.

[0048] Specifically, if the elastic modulus of the stress buffer layer 13 is less than 5 GPa, the strength of the stress buffer layer 13 will be too small. In this case, when the active material layer 12 undergoes a large volume change during charging and discharging, the stress buffer layer 13 may be excessively deformed and unable to effectively resist the stress generated by the volume change, which may lead to problems such as the collapse of the composite electrode. If the elastic modulus of the stress buffer layer 13 is greater than 50 GPa, the strength of the stress buffer layer 13 will be too large, which may cause the stress to be directly transmitted to the current collector 11 or the interior of the active material layer 12, which may also lead to problems such as the collapse of the composite electrode.

[0049] In this embodiment, by making the elastic modulus of the stress buffer layer 13 5GPa-50GPa, the stress buffer layer 13 has good stress absorption and dispersion capabilities. In this way, during the charging and discharging process, the stress buffer layer 13 can have appropriate strength, thereby effectively improving the overall strength of the composite electrode, effectively resisting the stress generated by the volume change of the active material layer 12, reducing the occurrence of problems such as electrode structure collapse, and thus improving the battery performance and cycle life.

[0050] Example 5 Optionally, the thickness of the stress buffer layer 13 along the first direction Z is 5μm-30μm.

[0051] Specifically, if the thickness of the stress buffer layer 13 along the first direction Z is less than 5 μm, the stress buffer layer 13 will be too thin and have insufficient strength. When the active material layer 12 undergoes volume changes during charging and discharging, the stress buffer layer 13 may be excessively deformed, making it difficult to effectively resist the stress generated by the volume changes, which may lead to problems such as collapse of the composite electrode. If the thickness of the stress buffer layer 13 along the first direction Z is greater than 30 μm, the overall thickness of the composite electrode will increase. Within the limited space of the battery, this will compress the volume that the active material layer 12 can accommodate, thereby reducing the energy density of the battery.

[0052] In this embodiment, by making the thickness of the stress buffer layer 13 along the first direction Z between 5μm and 30μm, the stress buffer layer 13 has sufficient strength so that it can effectively resist stress when the volume of the active material layer 12 changes. At the same time, the overall thickness of the composite electrode can be effectively controlled, thereby increasing the effective volume ratio of the active material layer 12 and thus improving the energy density of the battery.

[0053] Example 6 Optionally, the porosity of the stress buffer layer 13 is 30%-60%.

[0054] Specifically, if the porosity of the stress buffer layer 13 is less than 30%, the number of pores inside the stress buffer layer 13 will be small, the pore size will be small, and the connectivity will be poor. Like a dense solid film, the sparse pores will make it difficult to provide channels for ions to pass through. The migration path of ions between the active material layer 12 and the current collector 11 will be blocked, resulting in a significant increase in ion transport resistance and affecting the rate performance of the battery. If the porosity of the stress buffer layer 13 is higher than 60%, the pores inside will be too dense, which will make the support strength of the stress buffer layer 13 seriously insufficient. It will be difficult to resist the stress generated by the volume change of the active material layer 12. The stress buffer layer 13 itself is prone to collapse and breakage, which will lead to problems such as collapse of the composite electrode.

[0055] In this embodiment, when the porosity of the stress buffer layer 13 is between 30% and 60%, the pore network at this porosity has excellent connectivity, providing unobstructed migration channels for ions, reducing ion transport resistance, and improving the rate performance of the battery. At the same time, a reasonable porosity can improve the supporting strength of the stress buffer layer 13, so that while the stress buffer layer 13 undertakes the stress buffering function, it will not lose its supporting role due to excessive brittleness or softness, further reducing the occurrence of problems such as collapse of the composite electrode.

[0056] Example 7 Optionally, the active material layer 12 includes at least a mixed distribution of active material, an elastic structure, and an adhesive, wherein the elastic structure is used to form a cavity structure within the active material layer 12.

[0057] Specifically, for the positive electrode, the active material may include, but is not limited to, lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. Among these, lithium phosphates with an olivine structure may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4, abbreviated as LFP), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. For the negative electrode, the active material may include, but is not limited to, at least one of artificial graphite, natural graphite, mesophase carbon microspheres, hard carbon, soft carbon, silicon, silicon oxide, silicon carbon, and silicon alloys. This application does not specifically limit these aspects.

[0058] The adhesive may include one or more of polyvinylidene fluoride (PVDF), acrylic-modified PVDF, polyacrylate polymers, polyacrylic acid, polypropylene salts, polyimide, styrene-butadiene rubber, and styrene-acrylic rubber, and this application does not specifically limit the specific types. The adhesive is used to ensure good bonding between the components.

[0059] Furthermore, the active material layer 12 also includes a conductive agent, which can be one or more of carbon black, graphite, Ketjen black, carbon nanotubes, graphene and carbon fiber. This embodiment does not specifically limit this.

[0060] The elastic structure can be elastic polymer microspheres, such as polyimide microspheres. When the elastic structure is mixed with the active material and binder to form the active material layer 12, since the microspheres are spherical, there are gaps between the surface of the elastic structure and the active material; these gaps constitute a cavity structure. Thus, during charging and discharging, this cavity structure provides a buffer space when the active material layer undergoes volume changes, thereby alleviating stress concentration and further improving battery performance and cycle life. Furthermore, by incorporating a binder, good bonding between the components can be achieved, improving rate discharge performance.

[0061] Example 8 Optionally, the composite electrode also includes an electrolyte layer 14, which is connected to the side of the active material layer 12 away from the stress buffer layer 13.

[0062] Specifically, such as Figure 1 and Figure 2 As shown, a slurry containing a polymer electrolyte is coated on the side of the active material layer 12 away from the stress buffer layer 13, and then the polymer electrolyte is cross-linked in situ to form a stable gel structure through a UV curing process. This gel structure is the electrolyte layer 14.

[0063] In this embodiment, by providing an electrolyte layer 14, which is located on the outermost layer of the composite electrode, the ion conduction efficiency can be improved. Furthermore, the surface of the composite electrode can be protected, the stability of the interface between the composite electrode and the electrolyte can be enhanced, the interfacial impedance can be reduced, interfacial side reactions can be minimized, and the charge / discharge efficiency and cycle life of the battery can be improved.

[0064] Example 9 Optionally, the thickness of the electrolyte layer 14 along the first direction Z is 2μm-5μm.

[0065] Specifically, if the thickness of the electrolyte layer 14 along the first direction Z is less than 2 μm, the excessively thin electrolyte layer 14 is difficult to form a uniform and complete surface layer on the surface of the active material layer 12. The electrolyte is prone to direct side reactions with the active material of the composite electrode, thereby reducing the ion conduction efficiency and causing the battery charge and discharge efficiency to decrease. If the thickness of the electrolyte layer 14 along the first direction Z is greater than 5 μm, the excessively thick electrolyte layer 14 will prolong the transport path of ions from the electrolyte into the active material layer 12. The excessively long path will lead to an increase in ion transport resistance, resulting in a deterioration of the battery rate performance. In addition, the excessively thick electrolyte layer 14 will increase the overall thickness of the composite electrode. Within the limited assembly space of the battery, it may compress the volume of the active material layer 12, affecting the battery energy density.

[0066] In this embodiment, by setting the thickness of the electrolyte layer 14 along the first direction Z to 2μm-5μm, this thickness allows the electrolyte layer 14 to form a uniform and complete surface layer on the surface of the active material layer 12. This effectively reduces the direct erosion of the composite electrode surface layer by the electrolyte, reduces surface damage and loss of active material, improves the stability of the interface between the composite electrode and the electrolyte, and provides sufficient transport channels for ions, allowing ions to quickly pass through the electrolyte layer 14 of the composite electrode into the active material layer 12, improving ion conduction efficiency, reducing the increase in transport resistance due to excessively long paths, and improving the charge and discharge performance of the battery. Simultaneously, this thickness reduces the overall volume of the composite electrode, increasing the energy density of the battery.

[0067] In summary, the composite electrode provided in this application has at least the following advantages: In this embodiment, a stress buffer layer 13 is provided between the active material layer 12 and the current collector 11. The stress buffer layer 13 includes a support structure, which can improve the elastic modulus of the stress buffer layer 13 and improve the strength of the composite electrode. This can effectively resist the stress caused by the volume change of the active material layer 12, reduce the occurrence of problems such as electrode structure collapse, and improve the performance and cycle life of the battery.

[0068] Example 10 This application also provides a method for preparing a composite electrode, the method being used to prepare a composite electrode as described in any of the above embodiments, the method comprising: Step S01: Provide current collector 11; Step S02: Prepare stress buffer layer slurry, wherein the stress buffer layer slurry includes supporting structure raw materials; Step S03: Prepare the active substance layer slurry; Step S04: Apply the stress buffer layer slurry onto the current collector 11 to form a stress buffer layer 13; Step S05: The active material layer slurry is coated onto the stress buffer layer 13 to form the active material layer 12.

[0069] Specifically, steps S02 and S03 can be interchanged, or steps S02 and S03 can be performed simultaneously.

[0070] In step S02, the raw materials for the stress buffer layer include supporting structural materials, conductive agents, adhesives, and active substances. When preparing the stress buffer layer slurry, the above-mentioned raw materials are added to a suitable solvent in proportion, and thoroughly mixed and stirred at a certain temperature and stirring speed to form a uniform stress buffer layer slurry.

[0071] In step S03, the raw materials for the active material layer include active materials, elastic structures, binders, conductive agents, etc. When preparing the active material layer slurry, the above raw materials are added to a suitable solvent in a specific ratio, and thoroughly mixed and stirred at a certain temperature and stirring speed to form a uniform active material layer slurry.

[0072] In step S04, the prepared stress buffer layer slurry is uniformly coated onto the surface of the current collector using a suitable coating process, such as blade coating or roller coating. After coating, the slurry is dried and solvents are removed to allow it to solidify and form the stress buffer layer 13.

[0073] In step S05, the prepared active material layer slurry is uniformly coated onto the surface of the already formed stress buffer layer 13 using a suitable coating process, such as blade coating or roller coating. After coating, the slurry is dried and the solvent is removed, allowing it to solidify and form the active material layer 12.

[0074] Example 11 Optionally, the method for preparing the composite electrode further includes: Step S06: Prepare electrolyte layer slurry; Step S07: The electrolyte layer slurry is coated onto the active material layer to form the electrolyte layer 14.

[0075] Specifically, step S06 can be performed in parallel with steps S02 and S03, or after step S03, step S02, or step S01.

[0076] In step S06, the raw materials for the electrolyte layer 14 include polymer electrolytes, conductive agents, etc. These raw materials are added to a suitable solvent in a specific ratio and thoroughly mixed under appropriate temperature and stirring conditions to form a uniform electrolyte layer slurry.

[0077] In step S07, the prepared electrolyte layer slurry is uniformly coated onto the surface of the active material layer away from the stress buffer layer using a suitable coating method, such as spraying or spin coating. After coating, an ultraviolet curing process is used to allow the polymer electrolyte to crosslink in situ and form a stable gel structure, thus forming electrolyte layer 14.

[0078] In this embodiment, the composite electrode prepared by the composite electrode preparation methods in Examples 10 and 11 can effectively cope with the volume change of the active material layer, improve the stability of the electrode / electrolyte interface, significantly improve the cycle life of the composite electrode of the battery, and meet the application requirements of high cycle requirements such as power batteries and energy storage batteries.

[0079] Example 11 This application also provides a battery, which includes the composite electrode as described in any of the above embodiments.

[0080] A battery may include, but is not limited to, a casing, a cell, and terminals. The cell comprises two composite electrodes and a separator, wherein the two composite electrodes are a positive electrode and a negative electrode, respectively. The positive electrode, the separator, the negative electrode, and the separator are sequentially stacked. The cell is housed within the casing. The terminals include a positive terminal and a negative terminal, which are mounted opposite each other on the casing. The positive tab of the positive electrode is electrically connected to the positive terminal, and the negative tab of the negative electrode is electrically connected to the negative terminal.

[0081] Batteries can be lithium-ion batteries, lithium metal batteries, lithium-polymer batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-manganese-cobalt batteries, lithium-sulfur batteries, lithium-air batteries, nickel-metal hydride batteries, lithium-ion batteries, iron batteries, nano batteries, etc.

[0082] This application does not impose specific limitations on the shape of the battery. The battery may be in the form of a cylindrical, pouch-shaped, arc-shaped, pouch-shaped, square, cylindrical, rhomboid, or irregular shape.

[0083] It should be noted that in the embodiments of this application, the structure of the composite electrode is the same as that of the composite electrode described in any of the above embodiments, and its beneficial effects are also similar, so it will not be described in detail here.

[0084] Example 12 This application embodiment also provides a battery pack, the battery pack including the battery described above.

[0085] A battery pack can serve as a power source for electrical equipment, providing electrical energy to the equipment. A battery pack may include, but is not limited to, a housing, multiple battery groups, and a battery management system. Multiple battery groups are connected in series and / or parallel to form at least one battery module. The battery module is installed inside the housing. The battery management system is electrically connected to the battery and is used to monitor and manage parameters such as voltage and temperature of each battery.

[0086] It should be noted that in this embodiment, the structure of the battery is the same as that of the battery described in any of the above embodiments, and its beneficial effects are similar, so they will not be described in detail here.

[0087] Example 13 This application also provides an electrical device, which includes: a battery pack as described above or a battery as described in the above embodiments.

[0088] Electrical equipment can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical equipment.

[0089] It should be noted that in this embodiment, the structure of the battery pack is the same as that of the battery pack described in any of the above embodiments, and its beneficial effects are similar, so it will not be described in detail here.

[0090] It should be noted that the battery, battery pack, and electrical device involved in the above embodiments may include at least one of Embodiments 1 to 9. For example, Embodiment 1 can be implemented as an independent embodiment, Embodiments 1+2 can be implemented as independent embodiments, Embodiments 1+2+3 can be implemented as independent embodiments, Embodiments 1+2+4 can be implemented as independent embodiments, Embodiments 1+2+3+4 can be implemented as independent embodiments, Embodiments 1+2+4+5 can be implemented as independent embodiments, Embodiments 1+2+3+4+5 can be implemented as independent embodiments, Embodiments 1+2+4+6 can be implemented as independent embodiments, Embodiments 1+2+3+4+6 can be implemented as independent embodiments, Embodiments 1+2+4+5+6 can be implemented as independent embodiments, Embodiments 1+2+4+6+7 can be implemented as independent embodiments, and Embodiments 1+2+3+4+6+7 can be implemented as independent embodiments. Examples 1+2+4+5+6+7 can be implemented as independent examples, examples 1+2+3+4+5+6+7 can be implemented as independent examples, examples 1+2+4+6+8 can be implemented as independent examples, examples 1+2+3+4+6+8 can be implemented as independent examples, examples 1+2+4+5+6+8 can be implemented as independent examples, examples 1+2+3+4+5+6+8+9 can be implemented as independent examples, examples 1+2+4+6+7+8+8 can be implemented as independent examples, examples 1+2+4+5+6+7+8+9 can be implemented as independent examples, examples 1+2+3+4+5+6+7+8+9 can be implemented as independent examples, and so on, but are not limited to these, and will not be listed one by one here.

[0091] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

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

Claims

1. A composite electrode having a first orientation, characterized in that, The composite electrode comprises: current collector; An active material layer is provided, wherein the active material layer and the current collector are spaced apart along the first direction; A stress buffer layer, wherein one side of the stress buffer layer along the first direction is connected to the current collector, and the other side is connected to the active material layer; The stress buffer layer includes a support structure, which is used to improve the elastic modulus of the stress buffer layer.

2. The composite electrode according to claim 1, characterized in that, The supporting structure is any one of carbon fiber, PVDF-HFP composite doped with conductive carbon nanotubes / graphene, or SEBS copolymer.

3. The composite electrode according to claim 1 or 2, characterized in that, The stress buffer layer further includes an active material and an adhesive, wherein the active material, the adhesive, and the support structure are mixed and distributed, the content of the active material is 85wt%~90wt%, the content of the support structure is 2wt%~10wt%, and the content of the adhesive is 2wt%~10wt%.

4. The composite electrode according to any one of claims 1-3, characterized in that, The elastic modulus of the stress buffer layer is 5 GPa-50 GPa.

5. The composite electrode according to any one of claims 1-4, characterized in that, The thickness of the stress buffer layer along the first direction is 5μm-30μm.

6. The composite electrode according to any one of claims 1-5, characterized in that, The porosity of the stress buffer layer is 30%-60%.

7. The composite electrode according to any one of claims 1-6, characterized in that, The active material layer includes at least a mixed distribution of active material, conductive agent, elastic structure and adhesive, wherein the elastic structure is used to form a cavity structure within the active material layer.

8. The composite electrode according to any one of claims 1-7, characterized in that, The composite electrode also includes an electrolyte layer, which is connected to the side of the active material layer away from the stress buffer layer.

9. The composite electrode according to claim 8, characterized in that, The thickness of the electrolyte layer along the first direction is 2μm-5μm.

10. A method for preparing a composite electrode, characterized in that, The composite electrode preparation method is used to prepare the composite electrode as described in any one of claims 1-9, and the composite electrode preparation method includes: Provide current collectors; A stress buffer layer slurry is prepared, wherein the stress buffer layer slurry includes supporting structural raw materials; Preparation of active substance layer slurry; The stress buffer layer slurry is applied to the current collector to form a stress buffer layer; The active material layer slurry is applied onto the stress buffer layer to form the active material layer.

11. The method for preparing composite electrodes according to claim 10, characterized in that, The method for preparing the composite electrode also includes: Preparation of electrolyte layer slurry; The electrolyte layer slurry is coated onto the active material layer to form an electrolyte layer.

12. A battery, characterized in that, The battery includes: a composite electrode as described in any one of claims 1-9.

13. A battery pack, characterized in that, The battery pack includes the battery as described in claim 12.

14. An electrical appliance, characterized in that, The electrical equipment includes: the battery as described in claim 12 or the battery pack as described in claim 13.

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