A core electrode and its preparation method, a battery, and an electrical device thereof.

Abstract

This application provides an electrode core, its fabrication method, a battery, and an electrical device. The electrode core includes a surface electrode assembly and an inner electrode assembly. At least a portion of the positive current collector in the surface electrode assembly has a greater elongation at break than the positive current collector in the inner electrode assembly; and / or, at least a portion of the negative current collector in the surface electrode assembly has a greater elongation at break than the negative current collector in the inner electrode assembly. This electrode core design not only maintains the interface stability of the battery but also effectively improves the structural stability of the electrode tabs.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrode core and its preparation method, a battery, and an electrical device. Background Technology

[0002] As a next-generation energy storage technology, all-solid-state batteries are leading innovation in electric vehicles, large-scale energy storage systems, and high-end consumer electronics due to their core advantages such as high safety and long cycle life. Unlike liquid electrolytes, which can freely wet electrode particles, solid electrolytes have a purely solid physical contact with active materials. If the interfacial contact is insufficient, it will lead to a sharp increase in ion transport impedance, which will seriously affect the battery's rate performance, capacity utilization, and overall lifespan.

[0003] To construct this ideal solid-solid interface, isostatic pressing becomes an indispensable core step. This process applies ultra-high pressure of hundreds of megapascals to the encapsulated electrode core, forcing microscopic deformation of the solid electrolyte and electrode materials to maximize the contact area and reduce interfacial impedance. However, while this process tightly compacts the electrode sheet in the thickness direction, it also causes tensile stress in the length and width directions of the electrode core, leading to mechanical failures such as tab breakage.

[0004] Therefore, how to reduce the risk of tab breakage while ensuring the stability of the battery interface is an urgent problem to be solved. Summary of the Invention

[0005] This application provides a electrode core that, through a special structural composition, can not only maintain the interface stability of the battery, but also effectively improve the structural stability of the electrode tabs and reduce the risk of electrode tab breakage.

[0006] This application also provides a preparation method for preparing the above-mentioned electrode core.

[0007] This application also provides a battery including the aforementioned electrode core, thus having the advantage of stable electrochemical performance.

[0008] This application also provides an electrical device including the aforementioned battery, which thus has the advantage of a long standby time.

[0009] This application provides an electrode core, including a surface electrode assembly and an inner electrode assembly; at least a portion of the positive current collector in the surface electrode assembly has a greater elongation at break than the positive current collector in the inner electrode assembly; and / or, at least a portion of the negative current collector in the surface electrode assembly has a greater elongation at break than the negative current collector in the inner electrode assembly.

[0010] As described above, in the electrode core, the thickness of at least a portion of the positive current collector in the surface electrode assembly is greater than that of the positive current collector in the inner electrode assembly; and / or, the thickness of at least a portion of the negative current collector in the surface electrode assembly is greater than that of the negative current collector in the inner electrode assembly.

[0011] As described above, in the electrode core, at least a portion of the positive current collector in the surface electrode assembly has a breaking elongation greater than or equal to 5%; and / or, at least a portion of the negative current collector in the surface electrode assembly has a breaking elongation greater than or equal to 7%.

[0012] As described above, in the electrode core, the thickness of at least a portion of the positive current collector in the surface electrode assembly is 15 μm to 20 μm; and / or, the thickness of at least a portion of the negative current collector in the surface electrode assembly is 8 μm to 10 μm.

[0013] As described above, in the electrode core, at least a portion of the positive current collector in the inner electrode assembly has a tensile strength greater than or equal to 250 MPa; and / or, at least a portion of the negative current collector in the inner electrode assembly has a tensile strength greater than or equal to 630 MPa.

[0014] As described above, in the electrode core, at least a portion of the positive current collector in the inner electrode assembly has a greater tensile strength than the positive current collector in the outer electrode assembly; and / or, at least a portion of the negative current collector in the inner electrode assembly has a greater tensile strength than the negative current collector in the outer electrode assembly.

[0015] As described above, in the electrode core, the thickness of at least a portion of the positive current collector in the inner electrode assembly is 10 μm to 13 μm; and / or, the thickness of at least a portion of the negative current collector in the inner electrode assembly is 4.5 μm to 6 μm; and / or, the thickness of at least a portion of the positive active layer in the surface electrode assembly is 100 to 300 μm; and / or, the thickness of at least a portion of the negative active layer in the surface electrode assembly is 30 to 150 μm; and / or, the thickness of at least a portion of the positive active layer in the inner electrode assembly is 98 to 298 μm; and / or, the thickness of at least a portion of the negative active layer in the inner electrode assembly is 100 to 300 μm.

[0016] As described above, in the electrode core, at least a portion of the negative electrode current collector includes a negative electrode tab, which includes a negative electrode tab substrate and a nickel plating layer disposed on at least a portion of the surface of the negative electrode tab substrate.

[0017] In the electrode core described above, the thickness of the nickel plating layer is 1~3μm.

[0018] As described above, the electrode core includes a first electrode assembly, a second electrode assembly, and a third electrode assembly stacked together. The surface electrode assembly includes the first electrode assembly and the third electrode assembly, and the inner electrode assembly includes the second electrode assembly. The ratio of the number of current collectors in the first electrode assembly, the second electrode assembly, and the third electrode assembly is 1~3:3~7:1~3. And / or, the electrode core includes a negative electrode and a positive electrode stacked together. The negative electrode includes a negative current collector, a negative active layer, and an electrolyte layer. The negative active layer is disposed on at least a portion of the surface of the negative current collector, and the electrolyte layer is disposed on at least a portion of the surface of the negative active layer away from the negative current collector.

[0019] As described above, in the electrode core, the thickness H1 and quantity N1 of at least a portion of the negative current collector in the first electrode assembly and / or the third electrode assembly satisfy 40 / H1≤N1≤50 / H+1 with respect to the thickness H of the electrode core; and / or, the thickness H2 and quantity N2 of at least a portion of the positive current collector in the first electrode assembly and / or the third electrode assembly satisfy 75 / H2≤N2≤50 / H+1 with respect to the thickness H of the electrode core; wherein, the units of H1 and H2 are μm, the units of N1 and N2 are units, and the unit of H is mm.

[0020] This application also provides a method for preparing the electrode core according to any one of the above claims, comprising the following steps: sequentially stacking the surface electrode assembly and the inner electrode assembly and then performing isostatic pressing to obtain the electrode core.

[0021] In the preparation method described above, the pressure of the isostatic pressing treatment is 100~800 MPa.

[0022] This application also provides a battery comprising the electrode core described in any of the preceding claims, or the electrode core obtained by any of the preceding claims preparation methods.

[0023] This application also provides an electrical device, including the battery described above.

[0024] The electrode core provided in this application, through a special design, maintains a specific relationship between the fracture elongation and tensile strength of the positive and negative current collectors in the surface electrode assembly and the inner electrode assembly. This effectively reduces the risk of tab breakage while maintaining high interfacial stability, thereby enabling the battery to exhibit more stable electrochemical performance. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the electrode core according to one embodiment of this application. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] Under the high pressure environment of the isostatic pressing process, the current collector foil is prone to shrinkage, which in turn causes wrinkles, resulting in uneven density in different areas of the electrode core and ultimately affecting the electrochemical performance of the battery.

[0028] Through in-depth research, the inventors discovered that the most severe tearing and deformation of the tabs occurs at the root of the tabs in the surface layer of the electrode core, and that the shrinkage behavior of each layer of the electrode core is synchronous. Therefore, they proposed an idea to improve the overall shrinkage of the electrode core by enhancing the deformation resistance of the local current collectors. By configuring current collectors with different physicochemical parameters in different regions of the electrode core, the inventors aim to effectively balance the requirements of low shrinkage in the length and width directions of the electrode sheets and high toughness of the tabs during isostatic pressing without sacrificing energy density or increasing additional costs, thereby ensuring stable electrochemical performance of the battery.

[0029] Based on this, this application provides an electrode core, including a surface electrode assembly and an inner electrode assembly;

[0030] The elongation at break of at least a portion of the positive current collector in the surface electrode assembly is greater than that of the positive current collector in the inner electrode assembly; and / or, the elongation at break of at least a portion of the negative current collector in the surface electrode assembly is greater than that of the negative current collector in the inner electrode assembly.

[0031] Specifically, the electrode assembly includes stacked positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active layer disposed on at least a portion of the surface of the positive current collector. The negative electrode sheet includes a negative current collector and a negative active layer disposed on at least a portion of the surface of the negative current collector. The positive and negative electrode sheets in the electrode assembly are typically subjected to isostatic pressing after stacking. The direction of the isostatic pressing process distinguishes between surface electrode assemblies and inner electrode assemblies. The surface electrode assembly is on the isostatic pressing force-bearing surface, while the inner electrode assembly is relatively far from the isostatic pressing force-bearing surface compared to the surface electrode assembly. Depending on the direction of force on the electrode core under isostatic pressing, there can be one or more surface electrode assemblies. For example, when the electrode core is subjected to a single force direction, there is only one surface electrode assembly; or, when the electrode core is subjected to force from two different directions, there are two surface electrode assemblies.

[0032] The electrode core of this application may have a fracture elongation of at least a portion of the positive current collector in the surface electrode assembly that is greater than that of the positive current collector in the inner electrode assembly, or it may have a fracture elongation of at least a portion of the negative current collector in the surface electrode assembly that is greater than that of the negative current collector in the inner electrode assembly, or both of these conditions may be met, preferably both of these conditions.

[0033] It is understood that there may be multiple positive and negative electrodes in the surface electrode assembly and the inner electrode assembly, that is, there may also be multiple positive current collectors in each layer and multiple negative current collectors in each layer. Preferably, the elongation at break of the positive current collector in all surface electrode assemblies is greater than that of the positive current collector in all inner electrode assemblies, and preferably, the elongation at break of the negative current collector in all surface electrode assemblies is greater than that of the negative current collector in all inner electrode assemblies. More preferably, both satisfy the above conditions.

[0034] Through the above design, the current collector and tabs in the surface electrode assembly have relatively high toughness, allowing them to undergo certain deformations without breaking. At the same time, the structural stability of the inner electrode assembly is maintained. Without affecting the electrochemical performance of the battery, the overall core has a large elongation at break. Ultimately, the core absorbs the pressure deformation generated by isostatic pressure through the surface assembly. On the other hand, it can also reduce the overall deformation of the tabs and the stress at the root of the tabs, thereby effectively reducing the risk of tab tearing and achieving a synergistic improvement in the risk of core shrinkage and tab breakage.

[0035] The inventors discovered that when the thickness of at least a portion of the positive current collector in the surface electrode assembly is greater than that of the positive current collector in the inner electrode assembly, it is more advantageous to prepare an electrode core in which the elongation at break of at least a portion of the positive current collector in the surface electrode assembly is greater than that of the positive current collector in the inner electrode assembly.

[0036] Furthermore, when the thickness of at least a portion of the negative current collector in the surface electrode assembly is greater than that of the negative current collector in the inner electrode assembly, it is more advantageous to prepare an electrode core in which the elongation at break of at least a portion of the negative current collector in the surface electrode assembly is greater than that of the negative current collector in the inner electrode assembly.

[0037] In one specific implementation, at least a portion of the positive current collector in the surface electrode assembly has a fracture elongation greater than or equal to 5%.

[0038] In detail, a positive current collector with high elongation at break is beneficial to improving the overall deformation resistance of the electrode core. There may be multiple positive current collectors in the surface electrode assembly, and the elongation at break of the positive current collectors in at least some of the surface electrode assembly is within the above range. The elongation at break of these positive current collectors may be the same or different, as long as they are within the above range. The overall deformation resistance of the electrode core is further improved. Preferably, the elongation at break of the positive current collectors in all surface electrode assemblies is greater than or equal to 5%.

[0039] In one specific implementation, at least a portion of the negative current collector in the surface electrode assembly has a fracture elongation greater than or equal to 7%.

[0040] In detail, a negative electrode current collector with high elongation at break is beneficial to improving the overall deformation resistance of the electrode core. There may be multiple negative electrode current collectors in the surface electrode assembly, and the elongation at break of at least some of the negative electrode current collectors in the surface electrode assembly is within the above range. The elongation at break of these negative electrode current collectors may be the same or different, as long as they are within the above range. The overall deformation resistance of the electrode core is further improved. Preferably, the elongation at break of all negative electrode current collectors in the surface electrode assembly is greater than or equal to 7%.

[0041] In one specific embodiment, when the thickness of at least a portion of the positive current collector in the surface electrode assembly is 15μm to 20μm, it is more advantageous to prepare an electrode core with a fracture elongation greater than or equal to 5% for at least a portion of the positive current collector in the surface electrode assembly.

[0042] In one specific embodiment, when the thickness of at least a portion of the negative current collector in the surface electrode assembly is 8μm to 10μm, it is more advantageous to prepare an electrode core with a fracture elongation greater than or equal to 7% for at least a portion of the negative current collector in the surface electrode assembly.

[0043] In one specific embodiment, at least a portion of the positive current collector in the inner electrode assembly has a tensile strength greater than or equal to 250 MPa.

[0044] In detail, a positive current collector with high tensile strength is beneficial to improving the overall structural stability of the electrode core. There may be multiple positive current collectors in the inner electrode assembly, and the tensile strength of the positive current collectors in at least some of the inner electrode assemblies is within the above range. The tensile strength of these positive current collectors may be the same or different, as long as they are within the above range. The overall structural stability of the electrode core is further improved. Preferably, the tensile strength of the positive current collectors in all inner electrode assemblies is greater than or equal to 250 MPa.

[0045] In one specific embodiment, at least a portion of the negative current collector in the inner electrode assembly has a tensile strength greater than or equal to 630 MPa.

[0046] In detail, a negative electrode current collector with high tensile strength is beneficial to improving the overall structural stability of the electrode core. There may be multiple negative electrode current collectors in the inner electrode assembly, and the tensile strength of the negative electrode current collectors in at least some of the inner electrode assembly is within the above range. The tensile strength of these negative electrode current collectors may be the same or different, as long as they are within the above range. The overall structural stability of the electrode core is further improved. Preferably, the tensile strength of the negative electrode current collectors in all inner electrode assemblies is greater than or equal to 630 MPa.

[0047] Furthermore, when the tensile strength of at least a portion of the positive current collector in the inner electrode assembly is greater than that of the positive current collector in the outer electrode assembly, the outer electrode assembly and the inner electrode assembly are more well-matched, and the core's resistance to shrinkage and deformation is further improved.

[0048] Furthermore, when the tensile strength of at least a portion of the negative current collector in the inner electrode assembly is greater than that of the negative current collector in the outer electrode assembly, the outer electrode assembly and the inner electrode assembly are more well-matched, and the core's resistance to shrinkage and deformation is further improved.

[0049] The elongation at break and tensile strength of the current collector in the electrode core of this application can be tested using common testing methods in the field, and the final result is taken as an average value. For example, GB / T 228.1-2021 can be used for testing.

[0050] When testing the current collector in a battery, for example, the battery can be disassembled after discharge, and the positive and negative electrodes can be removed. The positive and negative electrodes are then immersed in anisole or butyl butyrate to deactivate the binder, thereby separating the active layer from the current collector. The elongation at break and tensile strength of the current collector can then be tested using the methods described above.

[0051] In one specific embodiment, the thickness of at least a portion of the positive current collector in the inner electrode assembly is 10 μm to 13 μm.

[0052] In detail, there may be multiple positive current collectors in the inner electrode assembly. At least some of the positive current collectors in the inner electrode assembly have a thickness within the above range. The thickness of these positive current collectors may be the same or different, as long as they are within the above range. This is beneficial to maintaining a larger energy density of the electrode core, thereby better balancing the electrode core structure and energy density. Preferably, the thickness of the positive current collectors in all the inner electrode assemblies is within the above range.

[0053] In one specific embodiment, the thickness of at least a portion of the negative current collector in the inner electrode assembly is 4.5 μm to 6 μm.

[0054] In detail, there may be multiple negative current collectors in the inner electrode assembly. At least some of the negative current collectors in the inner electrode assembly have a thickness within the above range. The thickness of these negative current collectors may be the same or different, as long as they are within the above range. This is beneficial to maintaining a larger energy density of the electrode core, thereby better balancing the electrode core structure and energy density. Preferably, the thickness of the negative current collectors in all the inner electrode assemblies is within the above range.

[0055] In one specific embodiment, the thickness of at least a portion of the positive electrode active layer in the surface electrode assembly is 100~300μm.

[0056] In detail, the thickness of the positive electrode active layer in this application refers to the total thickness of the positive electrode active layer in the positive electrode sheet. For example, when the positive electrode active layer in the positive electrode sheet is located on both surfaces of the positive electrode current collector, the thickness of the positive electrode active layer is the sum of the thicknesses of the two positive electrode active layers. There may be multiple positive electrode active layers in the surface electrode assembly. At least some of the positive electrode active layers in the surface electrode assembly have a thickness within the above range. The thicknesses of these positive electrode active layers may be consistent or inconsistent, as long as they are within the above range. This can effectively balance the energy density and rate performance of the electrode core. Preferably, the thickness of the positive electrode active layer in all surface electrode assemblies is within the above range.

[0057] In one specific embodiment, the thickness of at least a portion of the negative electrode active layer in the surface electrode assembly is 30~150 μm.

[0058] In detail, the thickness of the negative electrode active layer in this application refers to the total thickness of the negative electrode active layer in the negative electrode sheet. For example, when the negative electrode active layer in the positive electrode sheet is located on both surfaces of the positive electrode current collector, the thickness of the negative electrode active layer is the sum of the thicknesses of the two negative electrode active layers. There may be multiple negative electrode active layers in the surface electrode assembly. At least some of the negative electrode active layers in the surface electrode assembly have a thickness within the above range. The thicknesses of these negative electrode active layers may be consistent or inconsistent, as long as they are within the above range. This can effectively balance the energy density and rate performance of the electrode core. Preferably, the thickness of the negative electrode active layer in all surface electrode assemblies is within the above range.

[0059] In one specific embodiment, the thickness of at least a portion of the positive electrode active layer in the inner electrode assembly is 98~298 μm.

[0060] In detail, the thickness of the positive electrode active layer in this application refers to the total thickness of the positive electrode active layer in the positive electrode sheet. For example, when the positive electrode active layer in the positive electrode sheet is located on both surfaces of the positive electrode current collector, the thickness of the positive electrode active layer is the sum of the thicknesses of the two positive electrode active layers. There may be multiple positive electrode active layers in the inner electrode assembly. At least some of the inner electrode assembly have positive electrode active layers whose thicknesses are kept within the above range. The thicknesses of these positive electrode active layers may be consistent or inconsistent, as long as they are within the above range. This can effectively balance the energy density and rate performance of the electrode core. Preferably, the thickness of the positive electrode active layer in all inner electrode assembly is within the above range.

[0061] In one specific embodiment, the thickness of at least a portion of the negative electrode active layer in the inner electrode assembly is 100~300μm.

[0062] In detail, the thickness of the negative electrode active layer in this application refers to the total thickness of the negative electrode active layer in the negative electrode sheet. For example, when the negative electrode active layer in the positive electrode sheet is located on both surfaces of the positive electrode current collector, the thickness of the negative electrode active layer is the sum of the thicknesses of the two negative electrode active layers. There may be multiple negative electrode active layers in the inner electrode assembly. At least some of the negative electrode active layers in the inner electrode assembly have a thickness within the above range. The thicknesses of these negative electrode active layers may be consistent or inconsistent, as long as they are within the above range. This can effectively balance the energy density and rate performance of the electrode core. Preferably, the thickness of the negative electrode active layer in all the inner electrode assemblies is within the above range.

[0063] In one specific embodiment, at least a portion of the negative current collector in the electrode core includes a negative electrode tab, which includes a negative electrode tab substrate and a nickel plating layer disposed on at least a portion of the surface of the negative electrode tab substrate.

[0064] In detail, during the electrode assembly process, the electrolyte may absorb water and generate H2S. This gas corrodes the current collector, leading to a decrease in its tensile strength and an increase in its brittleness. Applying nickel plating to the negative electrode tab can effectively reduce this risk, improve its mechanical strength and elongation at break, and further reduce the risk of tab breakage. It is worth mentioning that maintaining a foil design at the non-tab areas also preserves the peel strength of the active layer, effectively preventing the active material from detaching and short-circuiting due to decreased adhesion between the two.

[0065] Furthermore, when the thickness of the nickel plating layer is 1~3μm, not only can the original structural performance of the tab be maintained, but the risk of tab breakage can also be further reduced.

[0066] In one specific embodiment, the electrode core includes a first electrode assembly, a second electrode assembly, and a third electrode assembly stacked together. The surface electrode assembly includes the first electrode assembly and the third electrode assembly, and the inner electrode assembly includes the second electrode assembly. The ratio of the number of current collectors in the first electrode assembly, the second electrode assembly, and the third electrode assembly is 1~3:3~7:1~3.

[0067] As mentioned above, multiple surface electrode assemblies can exist, and the electrode core of this application is divided into a specific three-layer structure according to a specific ratio of current collectors. Figure 1 This is a schematic diagram of the structure of the electrode core according to one embodiment of this application, as shown below. Figure 1 As shown, the positive electrode in the first electrode assembly is denoted as the first positive electrode, the negative electrode in the first electrode assembly is denoted as the first negative electrode, the positive electrode in the second electrode assembly is denoted as the second positive electrode, the negative electrode in the second electrode assembly is denoted as the second negative electrode, the positive electrode in the third electrode assembly is denoted as the third positive electrode, and the negative electrode in the third electrode assembly is denoted as the third negative electrode. This stacked design ensures that the first and third electrode assemblies are located on the two outer layers of the electrode core, while the second electrode assembly is located in the middle layer of the electrode core.

[0068] By designing the ratio of current collectors in different layers to the range mentioned above, the compatibility between layers can be further improved, the overall stability of the electrode core structure can be enhanced, and the risk of electrode tab breakage can be reduced.

[0069] In one specific embodiment, the electrode core includes a negative electrode sheet and a positive electrode sheet stacked together. The negative electrode sheet includes a negative electrode current collector, a negative electrode active layer, and an electrolyte layer. The negative electrode active layer is disposed on at least a portion of the surface of the negative electrode current collector, and the electrolyte layer is disposed on at least a portion of the surface of the negative electrode active layer away from the negative electrode current collector.

[0070] In detail, the negative electrode sheet obtained through the above design can further improve the interfacial contact between the negative electrode and the solid electrolyte in the battery, improve the electron and ion conduction efficiency in the battery, and reduce the internal resistance of the battery. In one specific embodiment, the thickness of the electrolyte layer is 28~148μm.

[0071] In one specific embodiment, the thickness H1 and quantity N1 of at least a portion of the negative current collector in the first electrode assembly and / or the third electrode assembly satisfy 40 / H1≤N1≤50 / H+1 with the thickness H of the electrode core.

[0072] Specifically, either the negative current collector in the first electrode assembly or the negative current collector in the third electrode assembly can satisfy the above conditions, preferably both. More specifically, there may be multiple negative current collectors in the first or third electrode assembly. Thickness H1 refers to the average thickness of the negative current collectors in the first or third electrode assembly. When the negative current collector in the surface electrode assembly satisfies the above inequality, the compatibility between the surface electrode assembly and the inner electrode assembly can be improved, further enhancing the structural stability of the electrode core.

[0073] In one specific implementation, the thickness H2 and quantity N2 of at least a portion of the positive current collector in the first electrode assembly and / or the third electrode assembly satisfy 75 / H2≤N2≤50 / H+1 with the thickness H of the electrode core.

[0074] Specifically, either the positive current collector in the first electrode assembly or the negative current collector in the third electrode assembly can satisfy the above conditions, preferably both. More specifically, there may be multiple positive current collectors in the first or third electrode assembly. Thickness H2 refers to the average thickness of the positive current collectors in the first or third electrode assembly. When the positive current collectors in the first or third electrode assembly satisfy the above inequality, the fit between the surface electrode assembly and the inner electrode assembly can be improved, further enhancing the structural stability of the electrode core.

[0075] The units for H1 and H2 are μm, the units for N1 and N2 are units, and the unit for H is mm.

[0076] This application also provides a method for preparing an electrode core, comprising the following steps: sequentially stacking the surface electrode assembly and the inner electrode assembly, followed by isostatic pressing to obtain the electrode core.

[0077] This application does not strictly limit the positive electrode active material in the positive electrode sheet. Taking lithium-ion solid-state cells as an example, it can be a commonly used positive electrode active material, such as a composite oxide of lithium with at least one of cobalt, manganese, nickel, or combinations thereof. More specifically, it can be at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate (LFP), lithium nickel manganese oxide, lithium-rich manganese-based materials, etc.

[0078] This application does not strictly limit the negative electrode active material in the negative electrode sheet. Taking lithium-ion solid-state battery cells as an example, it can be at least one of the commonly used negative electrode active materials, such as graphite, hard carbon, soft carbon, mesophase carbon microspheres, silicon-based negative electrode materials (mainly including silicon suboxide and silicon-carbon negative electrode), and tin-based negative electrode materials (mainly including tin and tin alloy).

[0079] When preparing solid-state batteries, for example, when the surface electrode assembly includes a first electrode assembly and a third electrode assembly, and the inner electrode assembly includes a second electrode assembly, the first electrode assembly, the second electrode assembly, and the third electrode assembly can be obtained by stacking. Then, the three stacked assemblies are stacked and assembled separately, and the battery is obtained after isostatic pressing.

[0080] In one specific implementation, the isostatic pressure treatment pressure is 100~800 MPa.

[0081] In detail, isostatic pressing is related to the microstructure of the electrode core, which in turn affects the macroscopic performance of the battery. Specifically, when the isostatic pressing pressure is maintained within the above-mentioned range, it is beneficial to increase the compaction density of the electrode sheets while maintaining the integrity of the electrode core structure, thereby improving the interfacial bonding force of the battery and promoting electron and ion transport.

[0082] This application also provides a battery, including the aforementioned electrode core, or the electrode core obtained by the aforementioned preparation method, which has advantages corresponding to the aforementioned electrode core, and will not be elaborated here.

[0083] It is worth noting that the battery in this application can be at least one of the following: a battery cell, a battery pack, a battery module, or a chassis.

[0084] The battery cell includes a casing and an electrode core encapsulated within the casing. The casing is provided with a positive electrode post and a negative electrode post that are electrically connected to the electrode core.

[0085] The battery pack is composed of multiple aforementioned battery cells. In one embodiment, the battery pack includes a common housing with multiple chambers inside, each chamber housing one battery cell. Optionally, the multiple battery cells may also adopt an integrated configuration sharing a solid electrolyte separator. The battery pack may also include a busbar for electrically connecting the cells and may integrate a sensing module for monitoring interface impedance or temperature.

[0086] The battery pack includes the aforementioned individual battery cells or battery packs. The battery pack can be installed as a whole module onto electrical equipment through its mechanical interface and high-voltage connector.

[0087] The chassis includes the chassis base and battery cells, battery packs or battery stacks mounted on the chassis base. For example, in the CTC scheme, the battery cells or battery packs are directly mounted and fixed in the space formed by the load-bearing structure of the chassis frame.

[0088] The battery described in this application can be a solid-state lithium-ion battery or a solid-state sodium-ion battery. This application does not impose any particular limitation on the battery preparation method, which can be obtained by referring to conventional methods in the art.

[0089] For example, in one specific implementation, a battery can be obtained by encapsulating the electrode core.

[0090] This application also provides an electrical device, including the aforementioned battery.

[0091] The electrical equipment used in this application can be conventional electrical equipment in the field, such as power equipment (e.g., electric vehicles, electric cars), electronic equipment (e.g., mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (e.g., watches, bracelets, VR glasses, etc.), energy storage power stations, etc., without any particular limitation.

[0092] The electrode core provided in this application will be described in detail below through specific embodiments.

[0093] The positive electrode in the first electrode assembly is designated as the first positive electrode, and the current collector in the first positive electrode is designated as the first positive current collector. The negative electrode in the first electrode assembly is designated as the first negative electrode, and the current collector in the first negative electrode is designated as the first negative current collector. The positive electrode in the second electrode assembly is designated as the second positive electrode, and the current collector in the second positive electrode is designated as the second positive current collector. The negative electrode in the second electrode assembly is designated as the second negative electrode, and the current collector in the second negative electrode is designated as the second negative current collector. The positive electrode in the third electrode assembly is designated as the third positive electrode, and the current collector in the third positive electrode is designated as the third positive current collector. The negative electrode in the third electrode assembly is designated as the third negative electrode, and the current collector in the third negative electrode is designated as the third negative current collector.

[0094] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially. The reagents involved can also be synthesized by conventional methods in the art.

[0095] Example 1

[0096] The preparation method of the electrode core in this embodiment includes the following steps:

[0097] 1) Nickel plating was performed on the tabs of the first, second, and third negative electrode current collectors, respectively, with a nickel plating layer thickness of 1 μm, to obtain first, second, and third negative electrode current collectors with nickel-plated tabs; wherein, the negative electrode current collectors were all copper foils, the thickness of the first and third negative electrode current collectors was 8 μm, the elongation at break was 7%, the tensile strength was 410 MPa, the thickness of the second negative electrode current collector was 4.5 μm, the tensile strength was 630 MPa, and the elongation at break was 4%;

[0098] 2) The negative electrode active material (pure silicon), conductive agent (carbon black), binder (styrene-butadiene rubber), and solvent (anisole) are mixed evenly at a mass ratio of 97.5:1:1.5:50 to obtain a negative electrode slurry. The negative electrode slurry is then coated onto both sides of each negative electrode current collector. After rolling and drying, the surface density is obtained to be 40 g / m². 2 The surface-coated negative electrode active layer consists of a first negative electrode current collector, a second negative electrode current collector, and a third negative electrode current collector;

[0099] 3) Solid electrolyte material (lithium, phosphorus, sulfur, and chlorine) and binder (polyvinylidene fluoride) in a mass ratio of 98:2 are mixed and stirred in a solvent (aniline ether) to obtain an electrolyte slurry. The electrolyte slurry is then coated onto both surfaces of the negative electrode current collector, which are coated with the negative electrode active layer, using an extrusion coating machine. After baking in an oven, the electrolyte layer density is 40 g / m³. 2 The first negative electrode, the second negative electrode, and the third negative electrode have a single-sided electrolyte layer thickness of 30 μm.

[0100] 3) The positive electrode current collectors are all aluminum foils. The thickness of the first and third positive electrode current collectors is 15 μm, the elongation at break is 5%, and the tensile strength is 215 MPa. The thickness of the second positive electrode current collector is 12 μm, the tensile strength is 250 MPa, and the elongation at break is 3%.

[0101] 4) The positive electrode active material (NCM811), conductive agent (carbon black), binder (polyvinylidene fluoride), and solvent (anisole) are mixed evenly at a mass ratio of 98.5:0.5:1:40 to obtain a positive electrode slurry. The positive electrode slurry is then coated onto both sides of each positive electrode current collector. After rolling and drying, the first, second, and third positive electrode active layers are formed, resulting in a final surface density of 476 g / m³. 2 The first positive electrode, the second positive electrode, and the third positive electrode;

[0102] 5) Stack the first negative electrode and the first positive electrode in sequence to obtain the first electrode assembly. Stack the second negative electrode and the second positive electrode in sequence to obtain the second electrode assembly. Stack the third negative electrode and the third positive electrode in sequence to obtain the third electrode assembly. Then stack the first, second and third electrode assemblies in sequence with the positive and negative electrodes close to each other. Under 600 MPa pressure, pressurize the electrode isostatically to obtain the battery cell.

[0103] The ratio of current collectors in the first, second, and third electrode assemblies is 20:49:20. The number of current collectors in the first and third negative electrodes is 5 each. The number of current collectors in the second negative electrode is 25, and the number of current collectors in the second positive electrode is 24. The thickness of the negative electrode active layer is 38 μm in all assemblies. The thickness of the positive electrode active layer is 191 μm in all assemblies. The total thickness of the electrode core is 10.55 mm.

[0104] Example 2

[0105] The preparation method of the electrode core in this embodiment is basically the same as that in Example 1. The difference is that the thickness of the first positive current collector and the third positive current collector is 20 μm, the elongation at break is 5.5%, and the tensile strength is 220 MPa. The thickness of the first negative current collector and the third negative current collector is 10 μm, the elongation at break is 7.5%, and the tensile strength is 415 MPa. The total thickness of the electrode core is 10.62 mm.

[0106] Example 3

[0107] The preparation method of the electrode core in this embodiment is basically the same as that in Example 1. The difference is that the thickness of the first positive current collector and the third positive current collector are both 20 μm, the elongation at break is 5.5%, the tensile strength is 220 MPa, and the total thickness of the electrode core is 10.6 mm.

[0108] Example 4

[0109] The preparation method of the electrode core in this embodiment is basically the same as that in Example 1. The difference is that the thickness of the first negative electrode current collector and the third negative electrode current collector is 10 μm, the elongation at break is 7.5%, the tensile strength is 415 MPa, and the total thickness of the electrode core is 10.57 mm.

[0110] Example 5

[0111] The preparation method of the electrode core in this embodiment is basically the same as that in Example 1. The difference is that the thickness of the third positive current collector is 12 μm, the elongation at break is 3%, the tensile strength is 250 MPa, and the total thickness of the electrode core is 10.535 mm.

[0112] Example 6

[0113] The preparation method of the electrode core in this embodiment is basically the same as that in Example 1. The difference is that the thickness of the third negative electrode current collector is 4.5 μm, the elongation at break is 4%, the tensile strength is 630 MPa, and the total thickness of the electrode core is 10.5325 mm.

[0114] Example 7

[0115] The preparation method of the electrode core in this embodiment is basically the same as that in Embodiment 1. The difference is that the thickness of the three layers of positive current collectors in the first positive current collector that are far away from the second electrode assembly and the three layers of positive current collectors in the third positive current collector that are far away from the second electrode assembly are both 15 μm, with a breaking elongation of 5% and a tensile strength of 215 MPa. The thickness of the remaining positive current collectors is 12 μm, with a breaking elongation of 3% and a tensile strength of 250 MPa. The total thickness of the electrode core is 1.538 mm.

[0116] Example 8

[0117] The preparation method of the electrode core in this embodiment is basically the same as that in Embodiment 1. The difference is that the thickness of the three negative electrode current collectors in the first negative electrode current collector that are far away from the second electrode assembly and the three negative electrode current collectors in the third negative electrode current collector that are far away from the second electrode assembly are both 8 μm, with a breaking elongation of 7% and a tensile strength of 410 MPa. The thickness of the remaining negative electrode current collectors is 4.5 μm, with a breaking elongation of 4% and a tensile strength of 630 MPa. The total thickness of the electrode core is 10.536 mm.

[0118] Example 9

[0119] The preparation method of the electrode core in this comparative example is basically the same as that in Example 1. The difference is that all positive electrode sheets use a 12μm positive current collector, with a breaking elongation of 3% and a tensile strength of 250MPa, resulting in a total electrode thickness of 10.52mm.

[0120] Example 10

[0121] The preparation method of the electrode core in this comparative example is basically the same as that in Example 1. The difference is that all negative electrode sheets use a negative electrode current collector with a thickness of 4.5 μm, a breaking elongation of 4%, and a tensile strength of 630 MPa, resulting in a total electrode sheet thickness of 10.515 mm.

[0122] Comparative Example 1

[0123] The preparation method of the electrode core in this comparative example is basically the same as that in Example 1. The difference is that all negative electrode sheets use a negative electrode current collector with a thickness of 4.5 μm, and the negative electrode current collector is not nickel plated. The elongation at break is 4% and the tensile strength is 630 MPa. All positive electrode sheets use a positive electrode current collector with a thickness of 12 μm, the elongation at break is 3%, and the tensile strength is 250 MPa. The total thickness of the electrode sheets is 10.485 mm.

[0124] Comparative Example 2

[0125] The preparation method of the electrode core in this comparative example is basically the same as that in Example 1. The difference is that all negative electrode sheets use a negative electrode current collector with a thickness of 4.5 μm, a breaking elongation of 4%, and a tensile strength of 630 MPa. All positive electrode sheets use a positive electrode current collector with a thickness of 12 μm, a breaking elongation of 3%, and a tensile strength of 250 MPa. The total thickness of the electrode sheets is 10.485 mm.

[0126] Experimental Example 1

[0127] After encapsulating the electrode core, a battery was obtained. The tensile strength and elongation at break of the electrode cores, the electrode tear ratio, vibration test results, and the energy density of the battery were measured for all embodiments and comparative examples. The results are shown in Table 1.

[0128] Vibration Test: First, a CT scan was performed on the battery to obtain an initial three-dimensional image of its internal structure. Then, it was charged at room temperature using a standard method (0.1C constant current charging to 4.2V, followed by constant voltage charging at 4.2V to a cutoff current of 0.05C, and resting for 30 minutes), and the voltage and AC internal resistance values ​​were recorded. The battery's AC internal resistance ACIR1 was also recorded as an initial benchmark for electrical performance. Next, the battery sample was fixed on a vibration table, and vibration was performed according to the national standard GB / T 2423.56, random vibration tests were conducted sequentially along the Z, Y, and X axes. On each test surface, the battery was subjected to random vibration for up to 15 hours based on a specific power spectral density and frequency. After the vibration ended, the battery was left to stand for 2 hours for observation, and the AC internal resistance ACIR2 of the battery was recorded again to capture any immediate changes in electrical performance. To rule out potential delayed damage, the battery was observed for two more days. After confirming that there were no abnormalities during this period, a final CT scan was performed. Through detailed comparison with the initial image, it was finally determined whether the vibration caused tearing damage to the positive / negative terminals of the battery, and the tab tearing ratio was recorded. The electrode core was placed under a two-dimensional imaging measuring instrument, and the appearance of the tab was inspected. The tab tearing condition was recorded. The tab tearing ratio = number of samples with tab tearing ÷ total number of samples.

[0129] Table 1

[0130]

[0131] As shown in Table 1, the electrode core of this application can effectively improve the breakage of the electrode tab, indicating that the electrode core has high structural stability.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A pole core, characterized by, Including surface electrode assembly and inner electrode assembly; The elongation at break of at least a portion of the positive current collector in the surface electrode assembly is greater than that of the positive current collector in the inner electrode assembly; and / or, the elongation at break of at least a portion of the negative current collector in the surface electrode assembly is greater than that of the negative current collector in the inner electrode assembly.

2. The pole core according to claim 1, characterized in that At least a portion of the positive current collector in the surface electrode assembly has a thickness greater than the positive current collector in the inner electrode assembly; and / or, The thickness of at least a portion of the negative current collector in the surface electrode assembly is greater than that of the negative current collector in the inner electrode assembly.

3. The pole core according to claim 1 or 2, characterized in that, At least a portion of the positive current collector in the surface electrode assembly has a breaking elongation greater than or equal to 5%; and / or, The elongation at break of at least a portion of the negative current collector in the surface electrode assembly is greater than or equal to 7%.

4. The pole core according to any one of claims 1 to 3, characterized in that The thickness of at least a portion of the positive current collector in the surface electrode assembly is 15 μm to 20 μm; and / or, The thickness of at least a portion of the negative electrode current collector in the surface electrode assembly is 8 μm to 10 μm.

5. The pole core according to any one of claims 1 to 4, characterized in that At least a portion of the positive current collector in the inner electrode assembly has a tensile strength greater than or equal to 250 MPa; and / or, The tensile strength of at least a portion of the negative current collector in the inner electrode assembly is greater than or equal to 630 MPa.

6. The pole core according to any one of claims 1 to 5, characterized in that At least a portion of the positive current collector in the inner electrode assembly has a greater tensile strength than the positive current collector in the outer electrode assembly; and / or, The tensile strength of at least a portion of the negative current collector in the inner electrode assembly is greater than that of the negative current collector in the outer electrode assembly.

7. The pole core according to any one of claims 1 to 6, characterized in that The thickness of at least a portion of the positive current collector in the inner electrode assembly is 10 μm to 13 μm; and / or, The thickness of at least a portion of the negative electrode current collector in the inner electrode assembly is 4.5 μm to 6 μm; and / or, The thickness of at least a portion of the positive active layer in the surface electrode assembly is 100~300 μm; and / or, The thickness of at least a portion of the negative electrode active layer in the surface electrode assembly is 30~150 μm; and / or, The thickness of at least a portion of the positive active layer in the inner electrode assembly is 98~298 μm; and / or, The thickness of at least a portion of the negative electrode active layer in the inner electrode assembly is 100~300μm.

8. The electrode core according to any one of claims 1-7, characterized in that, At least a portion of the negative current collector in the electrode core includes a negative electrode tab, the negative electrode tab including a negative electrode tab substrate and a nickel plating layer disposed on at least a portion of the surface of the negative electrode tab substrate.

9. The electrode core according to claim 8, characterized in that, The thickness of the nickel plating layer is 1~3μm.

10. The electrode core according to any one of claims 1-9, characterized in that, The electrode core includes a first electrode assembly, a second electrode assembly, and a third electrode assembly stacked together. The surface electrode assembly includes the first electrode assembly and the third electrode assembly, and the inner electrode assembly includes the second electrode assembly. The ratio of the number of current collectors in the first electrode assembly, the second electrode assembly, and the third electrode assembly is 1~3:3~7:1~3; and / or, The electrode core includes a negative electrode sheet and a positive electrode sheet stacked together. The negative electrode sheet includes a negative electrode current collector, a negative electrode active layer and an electrolyte layer. The negative electrode active layer is disposed on at least a portion of the surface of the negative electrode current collector, and the electrolyte layer is disposed on at least a portion of the surface of the negative electrode active layer away from the negative electrode current collector.

11. The pole core of claim 10, wherein, The thickness H1 and quantity N1 of at least a portion of the negative electrode current collector in the first electrode assembly and / or the third electrode assembly satisfy 40 / H1≤N1≤50 / H+1 with respect to the thickness H of the electrode core; and / or, The thickness H2 and quantity N2 of at least a portion of the positive current collector in the first electrode assembly and / or the third electrode assembly satisfy 75 / H2≤N2≤50 / H+1 with the thickness H of the electrode core; In this context, H1 and H2 are in μm, N1 and N2 are in units of individuals, and H is in mm.

12. A method of producing the electrode of any one of claims 1 to 11, characterized by, The process includes the following steps: stacking the surface electrode assembly and the inner electrode assembly in sequence, followed by isostatic pressing to obtain the electrode core.

13. The method of claim 12, wherein, The pressure for the isostatic pressing process is 100~800 MPa.

14. A battery, characterized by The electrode core includes the electrode core according to any one of claims 1-11, or the electrode core obtained by the preparation method according to claim 12 or 13.

15. An electrical device, characterized by Includes the battery as described in claim 14.

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