Electrode assembly, battery cell, battery and electric device

Abstract

The invention provides an electrode assembly, a battery monomer, a battery and a power utilization device, and belongs to the technical field of batteries. Wherein the battery monomer comprises a negative pole piece and a positive pole piece. The negative pole piece comprises a porous current collector and a first tab connected to at least one end of the porous current collector. The positive pole piece comprises a main body part and a second tab connected to at least one end of the main body part, the main body part and the porous current collector are stacked in the thickness direction of the porous current collector, the two ends of the porous current collector do not exceed the main body part in the first direction, and the first direction is perpendicular to the thickness direction of the porous current collector. The electrode assembly with the structure can apply a certain binding force to the edge of the porous current collector in the first direction to induce uniform deposition of lithium metal on the porous current collector so as to relieve the phenomenon that the lithium metal is deposited on the edge of the porous current collector to form dendritic crystals, so that the growth of the lithium metal dendritic crystals can be effectively inhibited, and the service life of the electrode assembly is prolonged. And the risk of short circuit of the electrode assembly is reduced.

Description

Electrode assembly, battery cell, battery and electrical device Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an electrode assembly, a battery cell, a battery, and an electrical device. Background Art

[0002] In recent years, new energy vehicles have developed by leaps and bounds. In the field of electric vehicles, power batteries, as the power source of electric vehicles, play an irreplaceable and important role. With the vigorous promotion of new energy vehicles, the demand for power battery products is also growing. Among them, batteries, as core components of new energy vehicles, have high requirements in terms of service life and safety. The battery cell of the battery is assembled into an electrode assembly (bare cell) by winding or laminating the positive electrode sheet, the negative electrode sheet and the isolation membrane, and then put into the shell and injected with electrolyte. However, the battery cells in the prior art are very prone to safety hazards such as short circuits during later use, which leads to a greater risk of use of the battery cells.

[0003] Summary of the Invention

[0004] The embodiments of the present application provide an electrode assembly, a battery cell, a battery, and an electrical device, which can effectively improve the safety of the battery cell.

[0005] In a first aspect, an embodiment of the present application provides a battery cell comprising a negative electrode sheet and a positive electrode sheet; the negative electrode sheet comprises a porous current collector and a first electrode tab connected to at least one end of the porous current collector; the positive electrode sheet comprises a main body and a second electrode tab connected to at least one end of the main body, and along the thickness direction of the porous current collector, the main body and the porous current collector are stacked, and along the first direction, both ends of the porous current collector do not exceed the main body, and the first direction is perpendicular to the thickness direction of the porous current collector.

[0006] In the above technical solution, the negative electrode sheet of the electrode assembly is provided with a porous current collector and a first pole ear protruding from at least one end of the porous current collector, and the positive electrode sheet of the electrode assembly is provided with a main body and a second pole ear connected to at least one end of the main body. By stacking the porous current collector of the negative electrode sheet and the main body of the positive electrode sheet, and setting the two ends of the porous current collector in the first direction so as not to exceed the main body of the positive electrode sheet, the porous current collector of the negative electrode sheet can be covered by the main body of the positive electrode sheet as a whole, thereby ensuring that the porous current collector of the negative electrode sheet can be protected by the main body. The pressure can, on the one hand, make the current density of the electrode assembly uniform during charging; on the other hand, it can also exert a certain restraining force on the edge of the porous current collector in the first direction, inducing the uniform deposition of lithium metal on the porous current collector, so as to alleviate the phenomenon of lithium metal deposition at the edge of the porous current collector to form dendrites, thereby effectively inhibiting the growth of lithium metal dendrites, which is beneficial to reducing the risk of short circuit in the electrode assembly, and can reduce the phenomenon of large amounts of "dead lithium" deposited in the porous current collector, causing active lithium loss and capacity attenuation, so as to improve the safety and performance of the electrode assembly.

[0007] In some embodiments, the main body includes a substrate and a positive electrode active material layer; the second electrode tab is connected to the substrate; the positive electrode active material layer is arranged on the side of the substrate facing the porous current collector in the thickness direction of the porous current collector, and along the first direction, both ends of the porous current collector do not exceed the positive electrode active material layer; wherein, an insulating layer is provided on the side of the positive electrode active material layer facing the porous current collector, and the insulating layer covers one end of the positive electrode active material layer.

[0008] In the above technical solution, the main body is provided with a substrate and a positive electrode active material layer arranged on one side of the substrate in the thickness direction of the porous current collector, so that the positive electrode active material layer and the porous current collector are arranged facing each other in the thickness direction of the porous current collector. By setting the two ends of the porous current collector in the first direction so as not to exceed the positive electrode active material layer, the positive electrode active material layer can cover the porous current collector, thereby achieving that the entire porous current collector can be subject to the binding force of the positive electrode active material layer. This structure is simple and easy to manufacture. In addition, by providing an insulating layer on the side of the positive active material layer facing the porous current collector, and the insulating layer covers one end of the positive active material layer, the electrode assembly using this structure can, on the one hand, play a certain blocking role for the lithium ions released from the portion of the positive active material layer that exceeds the porous current collector through the insulating layer, thereby helping to reduce the phenomenon of lithium ions being deposited at the edge of the porous current collector; on the other hand, the insulating layer can play a certain blocking role for the lithium metal dendrites formed at the edge of the porous current collector in the first direction, thereby alleviating the short circuit phenomenon between the negative electrode plate and the positive electrode plate due to lithium metal dendrites, thereby effectively reducing the safety hazards of the electrode assembly during use.

[0009] In some embodiments, the positive electrode active material layer includes a first region and a second region, and along the first direction, the first region is connected to at least one end of the second region; wherein the insulating layer covers the first region, and along the first direction, the second region does not exceed the porous current collector.

[0010] In the above technical solution, by setting the insulating layer to cover the first area of ​​the positive electrode active material layer, and setting the second area so that both ends in the first direction do not exceed the porous current collector, the size of the effective area where the positive electrode active material layer and the porous current collector are facing each other in the first direction is less than or equal to the size of the porous current collector. On the one hand, the lithium plating phenomenon of the electrode assembly during use can be alleviated, and on the other hand, the insulating layer can have a better barrier effect on the lithium metal dendrites formed at the edge of the porous current collector in the first direction.

[0011] In some embodiments, two insulating layers are provided on a side of the positive electrode active material layer facing the porous current collector, and the two insulating layers respectively cover both ends of the positive electrode active material layer.

[0012] In the above technical solution, two insulating layers are provided on the side of the positive electrode active material layer facing the porous current collector, so that the two insulating layers can respectively cover the two ends of the positive electrode active material layer in the first direction, thereby being able to block the lithium metal precipitated from the two ends of the positive electrode active material layer in the first direction, and being able to block the lithium metal dendrites formed on the two edges of the porous current collector in the first direction, thereby helping to further improve the safety of the electrode assembly.

[0013] In some embodiments, along the first direction, the insulating layer extends beyond one end of the positive electrode active material layer.

[0014] In the above technical solution, by arranging the insulating layer to have one end extending out of the positive electrode active material layer in the first direction, that is, the insulating layer has a portion exceeding one end of the positive electrode active material layer in the first direction, on the one hand, the insulating layer can better cover one end of the positive electrode active material layer, and on the other hand, the insulating layer can better protect one end of the positive electrode active material layer in the first direction, and facilitates the cutting and processing of the positive electrode sheet during the manufacturing process of the electrode assembly.

[0015] In some embodiments, along the thickness direction of the porous current collector, part of the insulating layer overlaps with the porous current collector, and the width of the overlapping part of the insulating layer and the porous current collector in the first direction is L, satisfying 1mm≤L≤3.5mm.

[0016] In the above technical solution, by setting the width of the overlapping part of the insulating layer and the porous current collector in the first direction to 1mm to 3.5mm, on the one hand, it can alleviate the phenomenon that the insulating layer is too effective in blocking lithium metal dendrites and blocking the precipitated lithium ions due to the overlapping width of the insulating layer and the porous current collector being too small, and can alleviate the problem that the manufacturing difficulty is greater due to the overlapping width of the insulating layer and the porous current collector being too small. On the other hand, it can alleviate the phenomenon that the electrode assembly loses too much capacity due to the overlapping width of the insulating layer and the porous current collector being too large, so that the insulating layer covers too large an area of ​​the positive electrode active material layer.

[0017] In some embodiments, the insulating layer is connected to the positive electrode active material layer.

[0018] In the above technical solution, the insulating layer is connected to the positive electrode active material layer so that the insulating layer can cover one end of the positive electrode active material layer in the first direction. On the one hand, the electrode assembly using this structure is beneficial to improving the covering effect of the insulating layer on the positive electrode active material layer and reducing the difficulty of assembling the electrode assembly. On the other hand, the insulating layer can also inhibit the precipitation of lithium ions in the area covered by the positive electrode active material layer, thereby reducing the risk of lithium precipitation of the electrode assembly during use and reducing the phenomenon of lithium ion deposition at the edge of the porous current collector.

[0019] In some embodiments, the positive electrode active material layer includes a first region and a second region, and along the first direction, the first region is connected to at least one end of the second region; wherein, the insulating layer covers the first region, and along the thickness direction of the porous current collector, the sum of the thickness of the first region and the insulating layer at the same position is D2, and the thickness of the second region is D3, satisfying, -80μm≤D2-D3≤10μm.

[0020] In the above technical solution, in the thickness direction of the porous current collector, the difference between the sum of the thicknesses of the first region of the positive electrode active material layer and the insulating layer at the same position and the thickness of the second region is set to -80μm to 10μm, that is, the insulating layer protrudes from the second region by 0μm to 10μm in the thickness direction of the porous current collector, or the second region protrudes from the insulating layer by 0μm to 80μm in the thickness direction of the porous current collector. The electrode assembly adopting this structure can alleviate the phenomenon of excessive gap between the positive electrode active material layer and the porous current collector. On the one hand, it can alleviate the phenomenon of excessive internal resistance of the electrode assembly caused by excessive gap between the positive electrode active material layer and the porous current collector. On the other hand, it can alleviate the risk of lithium plating in the electrode assembly caused by excessive gap between the positive electrode active material layer and the porous current collector.

[0021] In some embodiments, the positive electrode active material layer includes a first region and a second region, and along the first direction, the first region is connected to at least one end of the second region; wherein the insulating layer covers the first region, and the thickness of the first region is less than the thickness of the second region.

[0022] In the above technical solution, by setting the thickness of the first area of ​​the positive electrode active material layer where the insulating layer is provided to be smaller than the thickness of the second area of ​​the positive electrode active material layer, that is, a region with reduced thickness is formed on the positive electrode active material layer, and the insulating layer is provided in the region where the thickness of the positive electrode active material layer is reduced, the electrode assembly adopting this structure can increase the stability and reliability of the insulating layer connected to the positive electrode active material layer, so as to reduce the risk of the insulating layer falling off during use.

[0023] In some embodiments, the positive electrode active material layer includes a first region and a second region, and along the first direction, the first region is connected to at least one end of the second region; wherein, the insulating layer covers the first region, and along the thickness direction of the porous current collector, the surface of the first region facing the porous current collector is flush with the surface of the second region facing the porous current collector.

[0024] In the above technical solution, the surface of the first region of the positive electrode active material layer with an insulating layer facing the porous current collector is set to be flush with the surface of the second region of the positive electrode active material layer facing the porous current collector, that is, the surface of the positive electrode active material layer facing the porous current collector in the thickness direction of the porous current collector is flat, and the insulating layer is connected to the surface of the positive electrode active material layer facing the porous current collector to cover the first region of the positive electrode active material layer. This structure makes it easy to connect the insulating layer to the positive electrode active material layer, which is beneficial to reducing processing difficulty and improving production efficiency.

[0025] In some embodiments, the electrode assembly further includes an isolation membrane; the isolation membrane is disposed between the negative electrode sheet and the positive electrode sheet to separate the negative electrode sheet from the positive electrode sheet; wherein the insulating layer is connected to the surface of the isolation membrane facing the positive electrode active material layer.

[0026] In the above technical solution, the electrode assembly is also provided with a separator, which serves to separate the positive and negative electrode sheets, thereby reducing the risk of short circuits between the positive and negative electrode sheets. In addition, an insulating layer is connected to the surface of the separator facing the positive active material layer, thereby covering one end of the positive active material layer. This structure helps to reduce the difficulty of assembling the insulating layer.

[0027] In some embodiments, the main body includes a substrate and a positive electrode active material layer; the second electrode tab is connected to the substrate; the positive electrode active material layer is arranged on the side of the substrate facing the porous current collector in the thickness direction of the porous current collector, and along the first direction, both ends of the positive electrode active material layer do not extend beyond the porous current collector; wherein, along the first direction, at least one end of the positive electrode active material layer is connected to an insulating layer, and the insulating layer extends beyond one end of the porous current collector.

[0028] In the above technical solution, by setting the two ends of the positive electrode active material layer in the first direction not to exceed the porous current collector, the insulating layer is connected to at least one end of the positive electrode active material layer in the first direction, and the insulating layer exceeds one end of the porous current collector in the first direction, so that the insulating layer can provide a binding force to the edge of the porous current collector. The electrode assembly with this structure can effectively reduce the risk of lithium plating during use of the electrode assembly while ensuring that the entire porous current collector can be subjected to the pressure of the main body.

[0029] In some embodiments, along the first direction, both ends of the positive electrode active material layer are connected to the insulating layer.

[0030] In the above technical solution, by connecting insulating layers at both ends of the positive electrode active material layer along the first direction, the two insulating layers can extend out of the two ends of the porous current collector respectively along the first direction, thereby providing binding force to both edges of the porous current collector in the first direction, so as to alleviate the phenomenon of lithium metal deposition at the edge of the porous current collector to form dendrites, and thus can effectively inhibit the growth of lithium metal dendrites, which is beneficial to reduce the risk of short circuit of the electrode assembly, so as to improve the safety and performance of the electrode assembly.

[0031] In some embodiments, the elastic modulus of the insulating layer is E, satisfying E≥1 GPa.

[0032] In the above technical solution, an insulating layer with an elastic modulus greater than or equal to 1 GPa is used, so that the insulating layer has good strength and toughness. On the one hand, it can effectively reduce the damage of the insulating layer during use, so as to improve the service life of the electrode assembly. On the other hand, it can play a good blocking role on lithium metal dendrites, which is beneficial to reduce the phenomenon of the insulating layer being punctured by lithium metal dendrites, thereby effectively reducing the risk of use of battery cells.

[0033] In some embodiments, the insulating layer is an insulating tape or an insulating coating.

[0034] In the above technical solution, an insulating tape or an insulating coating is used as an insulating layer to cover one end of the positive electrode active material layer in the first direction. The insulating layer of this structure only needs to be bonded or coated on the side of the positive electrode active material layer facing the porous current collector, which facilitates the assembly of the electrode assembly and is beneficial to improving the production efficiency of the electrode assembly.

[0035] In some embodiments, along the first direction, at least one end of the main body extends beyond the porous current collector.

[0036] In the above technical solution, by setting at least one end of the main body in the first direction to extend beyond the porous current collector, it is ensured that the porous current collector can be subjected to the pressure of the main body, so that the porous current collector can be subjected to better expansion restraint force, thereby effectively alleviating the phenomenon of unlimited growth of lithium metal dendrites in the porous current collector.

[0037] In some embodiments, along the first direction, two ends of the main body are flush with two ends of the porous current collector.

[0038] In the above technical solution, by setting the two ends of the main body in the first direction to be flush with the porous current collector, the electrode assembly adopting this structure can effectively reduce the waste of the positive electrode active material layer while ensuring that the entire porous current collector can be subjected to the pressure of the main body, which is beneficial to reducing the manufacturing cost of the electrode assembly and saving the space occupied by the electrode assembly.

[0039] In some embodiments, along the thickness direction of the porous current collector, the maximum thickness of the first electrode tab is less than the thickness of the porous current collector.

[0040] In the above technical solution, by setting the maximum thickness of the first electrode tab in the thickness direction of the porous current collector to be smaller than the thickness of the porous current collector, on the one hand, it is convenient to subsequently assemble and connect the first electrode tab with other components. On the other hand, during the production process of the electrode assembly, when the two ends of the porous current collector of the negative electrode sheet in the first direction are set so as not to exceed the main body of the positive electrode sheet, it is convenient to effectively distinguish the porous current collector and the first electrode tab, thereby improving the manufacturing accuracy of the electrode assembly.

[0041] In some embodiments, the porous current collector and the first electrode tab are an integrated structure, and the first electrode tab is connected to one end of the porous current collector in the first direction; wherein, the first electrode tab includes a main body section and a transition section, along the first direction, the transition section is connected between the main body section and the porous current collector, and the thickness of the transition section in the thickness direction of the porous current collector gradually increases from one end close to the main body section to one end close to the porous current collector.

[0042] In the above technical solution, the porous current collector and the first pole ear are arranged as an integrally formed structure, so that the first pole ear is formed with a main section and a transition section connected between the porous current collector and the main section, and the thickness of the transition section in the thickness direction of the porous current collector gradually increases from one end close to the main section to the end close to the porous current collector, thereby realizing that the first pole ear protrudes from one end of the porous current collector. The negative electrode sheet with such a structure can effectively improve the structural strength of the first pole ear, and can effectively improve the connection strength between the first pole ear and the porous current collector.

[0043] In some embodiments, the porous current collector and the first electrode tab are split structures, the first electrode tab is connected to one side of the porous current collector in the thickness direction of the porous current collector, and the first electrode tab protrudes from one end of the porous current collector along the first direction.

[0044] In the above technical solution, the porous current collector and the first pole ear are arranged as a split structure, and the first pole ear is connected to one side of the porous current collector in the thickness direction of the porous current collector and then protrudes from one end of the porous current collector along the first direction, so as to realize that the first pole ear protrudes from one end of the porous current collector. The manufacturing difficulty of the negative electrode plate of this structure is relatively low, which is conducive to improving the production efficiency of the electrode assembly.

[0045] In some embodiments, along the thickness direction of the porous current collector, the thickness of the second tab is less than the thickness of the main body.

[0046] In the above technical solution, by setting the thickness of the second pole ear in the thickness direction of the porous current collector to be smaller than the thickness of the main body, on the one hand, it is convenient to subsequently assemble and connect the second pole ear with other components. On the other hand, during the production process of the electrode assembly, when the two ends of the porous current collector of the negative electrode sheet in the first direction are set so as not to exceed the main body of the positive electrode sheet, it is convenient to effectively distinguish the main body from the second pole ear, thereby improving the manufacturing accuracy of the electrode assembly.

[0047] In some embodiments, the electrode assembly is a wound electrode assembly, and the first direction is consistent with the winding axis direction of the electrode assembly.

[0048] In the above technical solution, by setting the electrode assembly as a winding structure, and the first direction is consistent with the winding axis direction of the electrode assembly, the electrode assembly with this structure is easy to manufacture and produce, which is beneficial to reduce the misalignment of the positive electrode sheet and the negative electrode sheet. On the other hand, it is only necessary to set the two ends of the porous current collector of the negative electrode sheet in the first direction so as not to exceed the positive electrode active material layer of the positive electrode sheet to ensure that the entire porous current collector is subjected to the pressure of the main body, thereby effectively suppressing the growth of lithium metal dendrites of the porous current collector.

[0049] In some embodiments, the porous current collector is made of foam metal.

[0050] In the above technical solution, the porous current collector made of foam metal enables the porous current collector to have the function of directly reacting with lithium ions to realize the input or output of electrical energy of the negative electrode plate, and the porous current collector with this structure can realize the deposition of lithium ions inside the porous current collector, which is beneficial to reduce the risk of lithium metal deposition on the surface of the porous current collector.

[0051] In some embodiments, the electrode assembly is a cylindrical structure.

[0052] In the above technical solution, by setting the electrode assembly as a cylindrical structure, the expansion force generated by the cylindrical electrode assembly during use is smaller, so that it is suitable for a porous current collector made of foam metal.

[0053] In a second aspect, an embodiment of the present application further provides a battery cell comprising a housing and the above-mentioned electrode assembly; the electrode assembly is accommodated in the housing.

[0054] In a third aspect, an embodiment of the present application further provides a battery comprising the above-mentioned battery cell.

[0055] In a fourth aspect, an embodiment of the present application further provides an electrical device comprising the above-mentioned battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0057] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0058] FIG2 is an exploded view of the structure of a battery provided in some embodiments of the present application;

[0059] FIG3 is an exploded view of the structure of a battery cell provided in some embodiments of the present application;

[0060] FIG4 is a cross-sectional view of an electrode assembly provided in some embodiments of the present application;

[0061] FIG5 is a partial cross-sectional view of an electrode assembly provided in some embodiments of the present application;

[0062] FIG6 is a partial cross-sectional view of an electrode assembly provided in some other embodiments of the present application;

[0063] FIG7 is a partial cross-sectional view of an electrode assembly provided in some further embodiments of the present application;

[0064] FIG8 is a cross-sectional view of a positive electrode sheet of an electrode assembly provided in some embodiments of the present application;

[0065] FIG9 is a partial enlarged view of the positive electrode sheet at point A shown in FIG8 ;

[0066] FIG10 is a cross-sectional view of a positive electrode sheet of an electrode assembly provided in some embodiments of the present application in another embodiment;

[0067] FIG11 is a partial enlarged view of the B portion of the positive electrode sheet shown;

[0068] FIG12 is a cross-sectional view of a positive electrode sheet of an electrode assembly provided in some embodiments of the present application in other embodiments;

[0069] FIG13 is a cross-sectional view of a positive electrode sheet of an electrode assembly provided in some embodiments of the present application in still other embodiments;

[0070] FIG14 is a partial enlarged view of the positive electrode piece at position C shown in FIG13;

[0071] FIG15 is a partial cross-sectional view of an electrode assembly provided in some other embodiments of the present application;

[0072] FIG16 is a partial enlarged view of a portion D of the electrode assembly shown in FIG15 ;

[0073] FIG17 is a partial cross-sectional view of an electrode assembly provided in yet other embodiments of the present application;

[0074] FIG18 is a partial cross-sectional view of an electrode assembly provided in yet other embodiments of the present application;

[0075] FIG19 is a partial enlarged view of point E of the electrode assembly shown in FIG18 .

[0076] Icon: 1000-vehicle; 100-battery; 10-box; 11-first box body; 12-second box body; 20-battery cell; 21-housing; 211-shell; 2111-opening; 212-end cap; 22-electrode assembly; 221-negative electrode sheet; 2211-porous current collector; 2212-first electrode tab; 2212a-main section; 2212b-transition section; 2213-weld stamp; 2214-protection Glue; 222-separating film; 223-positive electrode plate; 2231-main body; 22311-substrate; 22311a-first part; 22311b-second part; 22312-positive electrode active material layer; 22312a-first region; 22312b-second region; 2232-second electrode tab; 224-insulating layer; 200-controller; 300-motor; X-first direction; Y-thickness direction of the porous current collector. DETAILED DESCRIPTION

[0077] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0078] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0079] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0080] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0081] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0082] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0083] The term "plurality" used in this application refers to two or more (including two).

[0084] In this application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-ion batteries, or magnesium-ion batteries, etc., and the embodiments of this application do not limit this. Battery cells may be cylindrical, flat, rectangular, or other shapes, etc., and the embodiments of this application do not limit this. Battery cells are generally divided into three types based on the packaging method: cylindrical battery cells, prismatic battery cells, and soft-pack battery cells, and the embodiments of this application do not limit this.

[0085] The battery referred to in the embodiments of this application refers to a single physical module that includes one or more battery cells to provide higher voltage and capacity. For example, the battery referred to in this application may include a battery module or a battery pack. A battery generally includes a casing that encloses one or more battery cells or multiple battery modules. The casing prevents liquids or other foreign matter from affecting the charging or discharging of the battery cells.

[0086] A battery cell includes a housing, an electrode assembly, and an electrolyte. The housing is used to hold the electrode assembly and electrolyte. The electrode assembly consists of a positive electrode sheet, a negative electrode sheet, and a separator. A battery cell primarily operates by the movement of metal ions between the positive and negative electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive electrode collector. The portion of the positive electrode collector not coated with the positive active material layer serves as the positive tab, allowing power to be input or output from the positive electrode sheet through the positive tab. For lithium-ion batteries, for example, the positive electrode current collector can be made of aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide. The negative electrode sheet includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative electrode collector. The portion of the negative electrode collector not coated with the negative active material layer serves as the negative tab, allowing power to be input or output from the negative electrode sheet through the negative tab. The negative electrode current collector can be made of copper, and the negative electrode active material can be carbon or silicon. Alternatively, the negative electrode tab can be made directly from metal foam, with the foam rolled to form the negative electrode tab or welded to the metal foam. To ensure high current flow without melting, multiple positive electrode tabs are used, and multiple negative electrode tabs are used, stacked together.

[0087] The material of the isolation film may be polypropylene (PP) or polyethylene (PE), etc. In addition, the electrode assembly may be a wound structure or a laminated structure, but the present invention is not limited thereto.

[0088] Batteries offer outstanding advantages, including high energy density, low environmental pollution, high power density, long service life, wide adaptability, and low self-discharge coefficient, making them a crucial component of today's new energy development. A battery cell is composed of a positive electrode sheet, a negative electrode sheet, and a separator, assembled into an electrode assembly (bare cell) through winding or lamination. This assembly is then enclosed in a housing and finally filled with electrolyte. However, with the continuous development of battery technology, higher requirements have been placed on battery performance and safety. Therefore, the safety performance of the battery cell determines the safety of the battery during use.

[0089] The inventors discovered that during the later stages of battery life, the electrode assembly of a battery cell is prone to lithium metal deposition, primarily manifesting as lithium metal deposition on the negative electrode sheet of the electrode assembly. This often leads to surface deposition dendrites on the negative electrode sheet, which can easily damage the separator and create the risk of short-circuiting the electrode assembly. To address the safety issues caused by lithium metal deposition on the negative electrode sheet, a metal foam was used as the negative electrode sheet of the electrode assembly, and the width of the negative electrode sheet was set to be greater than that of the positive electrode sheet. This reduced the risk of lithium deposition in the electrode assembly while enabling lithium metal deposition within the negative electrode sheet. However, in a battery cell of this structure, since the part of the negative electrode plate of the foam metal that extends beyond the positive electrode plate is not restrained by the expansion force, and the pressure on the entire negative electrode plate is uneven, a large amount of "dead lithium" will be deposited in the part where the negative electrode plate extends beyond the positive electrode plate, resulting in loss of active lithium and rapid capacity decay. It is also very easy for lithium metal dendrites to grow infinitely, causing the isolation membrane of the electrode assembly to be punctured by lithium metal dendrites, resulting in a short circuit between the positive and negative electrode plates, which in turn causes a major safety hazard in the later use of the battery cell, which is not conducive to consumer safety.

[0090] Based on the above considerations, and in order to address the significant safety hazards posed by battery cells during later use, the inventors, after in-depth research, have designed an electrode assembly comprising a negative electrode sheet and a positive electrode sheet. The negative electrode sheet comprises a porous current collector and a first tab connected to at least one end of the porous current collector. The positive electrode sheet comprises a main body and a second tab connected to at least one end of the main body. The main body and the porous current collector are stacked along the thickness direction of the porous current collector. Along a first direction, neither end of the porous current collector extends beyond the main body. The first direction is perpendicular to the thickness direction of the porous current collector.

[0091] In the electrode assembly of this structure, the negative electrode sheet of the electrode assembly is provided with a porous current collector and a first pole ear protruding from at least one end of the porous current collector, and the positive electrode sheet of the electrode assembly is provided with a main body and a second pole ear connected to at least one end of the main body. By stacking the porous current collector of the negative electrode sheet and the main body of the positive electrode sheet, and setting the two ends of the porous current collector in the first direction not to exceed the main body of the positive electrode sheet, the porous current collector of the negative electrode sheet can be covered by the main body of the positive electrode sheet as a whole, thereby ensuring that the porous current collector of the negative electrode sheet can be protected by the main body. The pressure on the inside can, on the one hand, make the current density of the electrode assembly uniform during charging; on the other hand, it can also exert a certain restraining force on the edge of the porous current collector in the first direction, inducing the uniform deposition of lithium metal on the porous current collector, so as to alleviate the phenomenon of lithium metal deposition at the edge of the porous current collector to form dendrites, thereby effectively inhibiting the growth of lithium metal dendrites, which is beneficial to reducing the risk of short circuit in the electrode assembly, and can reduce the phenomenon of large amounts of "dead lithium" deposited in the porous current collector, causing active lithium loss and capacity attenuation, so as to improve the safety and performance of the electrode assembly.

[0092] The electrode assembly disclosed in the embodiments of this application can be used, but is not limited to, in electrical devices such as vehicles, ships, or aircraft. A power supply system comprising the battery cells and batteries disclosed in this application can be used to construct such electrical devices. This effectively reduces the risk of short circuits in the battery cells during subsequent use, thereby improving battery safety.

[0093] The present invention provides an electric device that uses a battery as a power source. The electric device may be, but is not limited to, a mobile phone, a tablet, a laptop computer, an electric toy, an electric tool, a battery-powered vehicle, an electric car, a ship, a spacecraft, etc. The electric toy may include a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy, and an electric airplane toy, etc. The spacecraft may include an airplane, a rocket, a space shuttle, and a spacecraft, etc.

[0094] For the convenience of description, the following embodiments are described by taking a vehicle 1000 as an example of an electrical device according to an embodiment of the present application.

[0095] Please refer to Figure 1, which is a schematic structural diagram of a vehicle 1000 provided in some embodiments of the present application. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000, and the battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0096] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0097] Please refer to Figure 2, which is an exploded view of the structure of a battery 100 provided in some embodiments of the present application. The battery 100 includes a housing 10 and a battery cell 20, which is used to be accommodated in the housing 10. The housing 10 is used to provide an assembly space for the battery cell 20, and the housing 10 can adopt various structures. In some embodiments, the housing 10 can include a first housing body 11 and a second housing body 12, which cover each other and together define an assembly space for accommodating the battery cell 20. The second housing body 12 can be a hollow structure with one end open, and the first housing body 11 can be a plate-like structure, with the first housing body 11 covering the open side of the second housing body 12, so that the first housing body 11 and the second housing body 12 jointly define an assembly space; the first housing body 11 and the second housing body 12 can also be hollow structures with one end open, with the open side of the first housing body 11 covering the open side of the second housing body 12. Of course, the box body 10 formed by the first box body 11 and the second box body 12 can be in various shapes, such as a cylinder, a cuboid, etc.

[0098] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0099] Each battery cell 20 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 can be cylindrical, flat, rectangular, or in other shapes. For example, in FIG2 , the battery cell 20 is cylindrical.

[0100] 3 and 4 , FIG3 is an exploded view of a battery cell 20 according to some embodiments of the present invention, and FIG4 is a cross-sectional view of an electrode assembly 22 according to some embodiments of the present invention. The battery cell 20 includes a housing 21 and an electrode assembly 22. The housing 21 is used to accommodate the electrode assembly 22.

[0101] The housing 21 can also be used to contain an electrolyte, such as an electrolyte solution. The housing 21 can have various structural forms. The housing 21 can also be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc.

[0102] In some embodiments, the housing 21 may include a shell 211 and an end cover 212, wherein the shell 211 is a hollow structure with an opening 2111 on one side, and the end cover 212 covers the opening 2111 of the shell 211 and forms a sealed connection to form a sealed space for accommodating the electrode assembly 22 and the electrolyte.

[0103] When assembling the battery cell 20 , the electrode assembly 22 may be placed in the housing 211 first, and the housing 211 may be filled with electrolyte. The end cap 212 may then be placed over the opening 2111 of the housing 211 .

[0104] The shell 211 can be of various shapes, such as a cylinder, a cuboid, etc. The shape of the shell 211 can be determined according to the specific shape of the electrode assembly 22. For example, if the electrode assembly 22 is a cylindrical structure, a cylindrical shell can be selected; if the electrode assembly 22 is a cuboid structure, a cuboid shell can be selected. Of course, the end cap 212 can also be of various structures, such as the end cap 212 being a plate-like structure, a hollow structure with an opening 2111 at one end, etc. For example, in Figure 3, the electrode assembly 22 is a cylindrical structure, and correspondingly, the shell 211 is a cylindrical structure, the end cap 212 is a cylindrical plate-like structure, and the end cap 212 covers the opening 2111 of the shell 211.

[0105] In some embodiments, the battery cell 20 may further include a positive electrode terminal and a negative electrode terminal. The positive electrode terminal is mounted on the end cap 212, and the negative electrode terminal is mounted on the end of the housing 211 opposite to the end cap 212. Of course, the positive electrode terminal may also be mounted on the end of the housing 211 opposite to the end cap 212, and the negative electrode terminal may be mounted on the end cap 212. Both the positive electrode terminal and the negative electrode terminal are used to electrically connect to the electrode assembly 22 to enable the input or output of electrical energy from the battery cell 20. The positive electrode terminal and the negative electrode terminal may be directly connected to the electrode assembly 22, for example, by welding or abutting, or the positive electrode terminal and the negative electrode terminal may be indirectly connected to the electrode assembly 22, for example, by abutting or welding the positive electrode terminal and the negative electrode terminal to the electrode assembly 22 through a current collecting member.

[0106] It is understandable that the shell 21 is not limited to the above structure. The shell 21 can also be other structures. For example, the shell 21 includes a shell body 211 and two end covers 212. The shell body 211 is a hollow structure with openings 2111 on opposite sides. One end cover 212 corresponds to an opening 2111 of the shell body 211 and forms a sealed connection to form a sealed space for accommodating the electrode assembly 22 and the electrolyte.

[0107] In some embodiments, the battery cell 20 may further include a pressure relief mechanism, which may be mounted on the end cap 212 or the housing 211. The pressure relief mechanism is used to release the pressure inside the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches a predetermined value.

[0108] Illustratively, the pressure relief mechanism may be a component such as an explosion-proof valve, an explosion-proof disk, an air valve, a pressure relief valve, or a safety valve.

[0109] It should be noted that the electrode assembly 22 is the component in the battery cell 20 where the electrochemical reaction occurs. The electrode assembly 22 may include a negative electrode sheet 221, a separator 222, and a positive electrode sheet 223. The electrode assembly 22 may be a wound structure formed by winding the negative electrode sheet 221, the separator 222, and the positive electrode sheet 223, or a laminated structure formed by stacking the negative electrode sheet 221, the separator 222, and the positive electrode sheet 223. For example. In Figure 4, the electrode assembly 22 is a wound structure formed by winding the negative electrode sheet 221, the separator 222, and the positive electrode sheet 223.

[0110] According to some embodiments of the present application, with reference to FIG3 and FIG4 , and further with reference to FIG5 , FIG5 is a partial cross-sectional view of an electrode assembly 22 provided in some embodiments of the present application. The present application provides an electrode assembly 22, which includes a negative electrode sheet 221 and a positive electrode sheet 223. The negative electrode sheet 221 includes a porous current collector 2211 and a first electrode tab 2212 connected to at least one end of the porous current collector 2211. The positive electrode sheet 223 includes a main body 2231 and a second electrode tab 2232 connected to at least one end of the main body 2231. Along the thickness direction Y of the porous current collector, the main body 2231 and the porous current collector 2211 are stacked. Along the first direction X, both ends of the porous current collector 2211 do not extend beyond the main body 2231. The first direction X is perpendicular to the thickness direction Y of the porous current collector.

[0111] The porous current collector 2211 of the negative electrode plate 221 has a structure with multiple pores, and can be a foam metal or a mesh structure woven from metal wires.

[0112] The first electrode tab 2212 is connected to at least one end of the porous current collector 2211, that is, the first electrode tab 2212 is connected to at least one end of the porous current collector 2211 in the thickness direction Y perpendicular to the porous current collector. The first electrode tab 2212 can be connected to one end of the porous current collector 2211, or both ends of the porous current collector 2211 can be connected to the first electrode tab 2212. The first electrode tab 2212 serves as the negative output electrode of the electrode assembly 22. The first electrode tab 2212 is used to connect to the negative electrode terminal to realize the input or output of electrical energy of the electrode assembly 22.

[0113] For example, in FIG5 , the first electrode tab 2212 is connected to one end of the porous current collector 2211 in the first direction X. Of course, in other embodiments, the first electrode tab 2212 may also be connected to one end of the porous current collector 2211 in a direction perpendicular to the first direction X and the thickness direction Y of the porous current collector. It should be noted that the first electrode tab 2212 is connected to one end of the porous current collector 2211 in the first direction X. The first electrode tab 2212 may be connected to one end of the porous current collector 2211 in the first direction X, or may be connected to the side of the porous current collector 2211 facing the main body 2231 in the thickness direction Y of the porous current collector. It is sufficient that the first electrode tab 2212 extends along the first direction X and protrudes from one end of the porous current collector 2211 in the first direction X.

[0114] It should be noted that in Figures 3, 4, and 5, the electrode assembly 22 is a wound structure, the thickness direction Y of the porous current collector is the radial direction of the electrode assembly 22, and the first direction X is the width direction of the negative electrode sheet 221, which is also the extension direction of the winding center axis of the electrode assembly 22. Of course, the first direction X can also be the winding direction of the electrode assembly 22, that is, the first direction X is the extension direction of the negative electrode sheet 221. When the first direction X is the extension direction of the negative electrode sheet 221, the first direction X and the thickness direction Y of the porous current collector are mutually perpendicular, which means that the tangent line of the point where the first direction X intersects the thickness direction Y of the porous current collector in the first direction X is perpendicular to the thickness direction Y of the porous current collector. In some embodiments, if the electrode assembly 22 is a laminated structure, that is, the negative electrode sheet 221 and the positive electrode sheet 223 are alternately stacked along the thickness direction Y of the porous current collector, in such embodiments, the first direction X can be the width direction of the negative electrode sheet 221 or the length direction of the negative electrode sheet 221. Of course, if the negative electrode sheets 221 are continuously arranged and folded into a “Z”-shaped structure, and the positive electrode sheets 223 are alternately stacked between the negative electrode sheets 221 in the laminated electrode assembly 22 , the first direction X is the width direction of the negative electrode sheets 221 .

[0115] The second electrode tab 2232 is connected to at least one end of the main body 2231, that is, the second electrode tab 2232 is connected to at least one end of the main body 2231 in the thickness direction Y perpendicular to the porous current collector. The second electrode tab 2232 can be connected to one end of the main body 2231, or both ends of the main body 2231 can be connected to the second electrode tab 2232. The second electrode tab 2232 serves as the positive output electrode of the electrode assembly 22. The second electrode tab 2232 is used to connect to the positive electrode terminal to realize the input or output of electrical energy of the electrode assembly 22.

[0116] For example, in FIG5 , the second electrode tab 2232 is connected to one end of the main body 2231 in the first direction X. Of course, in other embodiments, the second electrode tab 2232 may also be connected to one end of the main body 2231 in the thickness direction Y perpendicular to the first direction X and the porous current collector.

[0117] It should be noted that the second pole tab 2232 is a portion protruding from one end of the main body 2231 in the first direction X, and the thickness of the second pole tab 2232 in the thickness direction Y of the porous current collector is less than the thickness of the main body 2231. That is to say, the main body 2231 of the positive electrode sheet 223 is the portion of the positive electrode sheet 223 used to be stacked with the porous current collector 2211 of the negative electrode sheet 221, and the main body 2231 of the positive electrode sheet 223 can provide extrusion force for the porous current collector 2211 of the negative electrode sheet 221 in the thickness direction Y of the porous current collector.

[0118] Along the first direction X, both ends of the porous current collector 2211 do not extend beyond the main body 2231. That is, in the first direction X, both ends of the main body 2231 may extend beyond the porous current collector 2211, or one end of the main body 2231 may extend beyond the porous current collector 2211 and the other end may be flush with one end of the porous current collector 2211. Alternatively, both ends of the main body 2231 may be flush with both ends of the porous current collector 2211. For example, in FIG. 5 , both ends of the main body 2231 extend beyond the porous current collector 2211.

[0119] The negative electrode sheet 221 of the electrode assembly 22 is provided with a porous current collector 2211 and a first pole ear 2212 protruding from at least one end of the porous current collector 2211. The positive electrode sheet 223 of the electrode assembly 22 is provided with a main body 2231 and a second pole ear 2232 connected to at least one end of the main body 2231. By stacking the porous current collector 2211 of the negative electrode sheet 221 and the main body 2231 of the positive electrode sheet 223, and setting the two ends of the porous current collector 2211 in the first direction X so that neither of them exceeds the main body 2231 of the positive electrode sheet 223, the porous current collector 2211 of the negative electrode sheet 221 can be covered by the main body 2231 of the positive electrode sheet 223 as a whole, thereby ensuring that the negative electrode The porous current collector 2211 of the sheet 221 can be subjected to the pressure of the main body 2231. On the one hand, it can make the current density of the electrode assembly 22 uniform during charging. On the other hand, it can also exert a certain restraining force on the edge of the porous current collector 2211 in the first direction X, inducing the uniform deposition of lithium metal on the porous current collector 2211, so as to alleviate the phenomenon of lithium metal deposition at the edge of the porous current collector 2211 to form dendrites, and thus can effectively inhibit the growth of lithium metal dendrites, which is beneficial to reducing the risk of short circuit in the electrode assembly 22, and can reduce the phenomenon of a large amount of "dead lithium" deposited in the porous current collector 2211, resulting in active lithium loss and capacity attenuation, so as to improve the safety and performance of the electrode assembly 22.

[0120] According to some embodiments of the present application, refer to Figures 4 and 5. The main body 2231 includes a substrate 22311 and a positive electrode active material layer 22312. The second tab 2232 is connected to the substrate 22311. The positive electrode active material layer 22312 is provided on a side of the substrate 22311 facing the porous current collector 2211 in the thickness direction Y of the porous current collector. Along the first direction X, both ends of the porous current collector 2211 do not extend beyond the positive electrode active material layer 22312. The side of the positive electrode active material layer 22312 facing the porous current collector 2211 is provided with an insulating layer 224, and the insulating layer 224 covers one end of the positive electrode active material layer 22312.

[0121] Among them, along the thickness direction Y of the porous current collector, negative electrode sheets 221 are arranged on both sides of the positive electrode sheet 223. Correspondingly, both sides of the substrate 22311 of the main body 2231 of the positive electrode sheet 223 are coated with positive electrode active material layers 22312. The positive electrode active material layer 22312 and the porous current collector 2211 of the negative electrode sheet 221 are the areas where chemical reactions occur in the battery cell 20, and they mainly rely on the movement of metal ions between the positive electrode active material layer 22312 and the porous current collector 2211 to work.

[0122] Illustratively, the material of the positive electrode active material layer 22312 can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide, etc.

[0123] In Figure 5, the second pole tab 2232 and the substrate 22311 are an integrated structure, that is, the second pole tab 2232 is a region of the substrate 22311 extending out of the positive electrode active material layer 22312 and the insulating layer 224 in the first direction X. Of course, in other embodiments, the second pole tab 2232 and the substrate 22311 can also be a split structure, and the second pole tab 2232 is connected to one end of the substrate 22311 in the first direction X by welding or the like, so that the second pole tab 2232 protrudes from one end of the main body 2231 in the first direction X.

[0124] Exemplarily, the material of the substrate 22311 can be copper, iron, aluminum, steel, aluminum alloy, etc.

[0125] An insulating layer 224 is provided on the side of the positive electrode active material layer 22312 facing the porous current collector 2211. The insulating layer 224 covers one end of the positive electrode active material layer 22312. That is, the insulating layer 224 is provided on the side of the positive electrode active material layer 22312 facing the porous current collector 2211 in the thickness direction Y of the porous current collector, and the projection of the insulating layer 224 in the thickness direction Y of the porous current collector covers one end of the positive electrode active material layer 22312 in the first direction X. In other words, the insulating layer 224 extends along the first direction X to the edge of the positive electrode active material layer 22312 in the first direction X. In this embodiment, the insulating layer 224 can be connected to the positive electrode active material layer 22312 or to the separator 222 provided between the positive electrode sheet 223 and the negative electrode sheet 221.

[0126] In Figure 5, both ends of the porous current collector 2211 in the first direction X are configured to have a structure that does not exceed the positive electrode active material layer 22312, and an insulating layer 224 is provided on the side of the positive electrode active material layer 22312 facing the porous current collector 2211 to achieve a structure in which both ends of the porous current collector 2211 in the first direction X do not exceed the main body 2231, thereby achieving the two edges of the porous current collector 2211 in the first direction X being able to be subject to the expansion restraint force of the main body 2231 of the positive electrode sheet 223. Of course, in some embodiments, referring to FIG6 , which is a partial cross-sectional view of an electrode assembly 22 provided in yet other embodiments of the present application, the electrode assembly 22 may also have other structures. The main body 2231 includes a positive electrode active material layer 22312 and an insulating layer 224 connected to both ends of the positive electrode active material layer 22312 in the first direction X. The positive electrode active material layer 22312 is configured to have both ends in the first direction X not extending beyond the porous current collector 2211. The insulating layer 224 extends beyond one end of the porous current collector 2211 along the first direction X, thereby achieving a structure in which both ends of the porous current collector 2211 in the first direction X do not extend beyond the main body 2231. This ensures that both edges of the porous current collector 2211 in the first direction X are subject to the expansion restraint force of the main body 2231 of the positive electrode sheet 223. In this embodiment, the second tab 2232 is the region of the substrate 22311 extending beyond the insulating layer 224 in the first direction X.

[0127] It should be noted that, in some embodiments, the main body 2231 of the positive electrode sheet 223 of the electrode assembly 22 may also not be provided with an insulating layer 224. Referring to FIG7, FIG7 is a partial cross-sectional view of the electrode assembly 22 provided in some embodiments of the present application. The main body 2231 includes a substrate 22311 and a positive electrode active material layer 22312. The substrate 22311 includes a first portion 22311a and a second portion 22311b connected to both ends of the first portion 22311a in a first direction X. The thickness of the first portion 22311a in the thickness direction Y of the porous current collector is less than that of the second portion 22311b. The thickness of the second part 22311b is adjusted, and the positive electrode active material layer 22312 is arranged on the side of the first part 22311a facing the porous current collector 2211. The positive electrode active material layer 22312 is located between the two second parts 22311b in the first direction X. In the thickness direction Y of the porous current collector, the surface of the positive electrode active material layer 22312 facing the porous current collector 2211 is flush with the surface of the second part 22311b facing the porous current collector 2211. That is to say, the substrate 22311 is a structure thickened at both ends of the positive electrode active material layer 22312 along the first direction X. In this embodiment, both ends of the positive electrode active material layer 22312 in the first direction X do not extend beyond the porous current collector 2211, and the second portion 22311b extends beyond one end of the porous current collector 2211 in the first direction X, thereby achieving a structure in which both ends of the porous current collector 2211 in the first direction X do not extend beyond the main body 2231. This ensures that both edges of the porous current collector 2211 in the first direction X can be subjected to the expansion restraint force of the main body 2231 of the positive electrode sheet 223. In this embodiment, the second electrode tab 2232 is connected to the end of the second portion 22311b facing away from the first portion 22311a in the first direction X.

[0128] The main body 2231 is provided with a substrate 22311 and a positive electrode active material layer 22312 arranged on one side of the substrate 22311 in the thickness direction Y of the porous current collector, so that the positive electrode active material layer 22312 and the porous current collector 2211 are arranged facing each other in the thickness direction Y of the porous current collector. By setting the two ends of the porous current collector 2211 in the first direction X so as not to exceed the positive electrode active material layer 22312, the positive electrode active material layer 22312 can cover the porous current collector 2211, thereby achieving that the entire porous current collector 2211 can be subject to the binding force of the positive electrode active material layer 22312. This structure is simple and easy to manufacture. In addition, by providing an insulating layer 224 on the side of the positive electrode active material layer 22312 facing the porous current collector 2211, and the insulating layer 224 covers one end of the positive electrode active material layer 22312, the electrode assembly 22 using this structure can, on the one hand, play a certain blocking role through the insulating layer 224 on the lithium ions released from the portion of the positive electrode active material layer 22312 that exceeds the porous current collector 2211, thereby helping to reduce the phenomenon of lithium ions being deposited at the edge of the porous current collector 2211. On the other hand, the insulating layer 224 can play a certain blocking role on the lithium metal dendrites formed at the edge of the porous current collector 2211 in the first direction X, thereby alleviating the short circuit phenomenon between the negative electrode plate 221 and the positive electrode plate 223 due to lithium metal dendrites, thereby effectively reducing the safety hazards of the electrode assembly 22 during use.

[0129] According to some embodiments of the present application, referring to FIG5 and further referring to FIG8 and FIG9, FIG8 is a cross-sectional view of the positive electrode sheet 223 of the electrode assembly 22 provided in some embodiments of the present application, and FIG9 is a partial enlarged view of the positive electrode sheet 223 shown in FIG8 at point A. The positive electrode active material layer 22312 includes a first region 22312a and a second region 22312b. Along the first direction X, the first region 22312a is connected to at least one end of the second region 22312b. The insulating layer 224 covers the first region 22312a. Along the first direction X, the second region 22312b does not extend beyond the porous current collector 2211.

[0130] Among them, the first region 22312a is the region where the positive electrode active material layer 22312 is covered by the insulating layer 224 in the thickness direction Y of the porous current collector, and the second region 22312b is the region where the positive electrode active material layer 22312 is not covered by the insulating layer 224 in the thickness direction Y of the porous current collector.

[0131] For example, in FIG8 , two insulating layers 224 are provided on the side of the positive electrode active material layer 22312 facing the porous current collector 2211 , and the two insulating layers 224 respectively cover both ends of the positive electrode active material layer 22312 in the first direction X. Accordingly, the positive electrode active material layer 22312 is formed with two first regions 22312 a, and the two regions are respectively connected to both ends of the second region 22312 b along the first direction X. Of course, in some embodiments, only one insulating layer 224 may be provided on the side of the positive electrode active material layer 22312 facing the porous current collector 2211 , and accordingly, the positive electrode active material layer 22312 is formed with only one first region 22312 a.

[0132] Along the first direction X, the second region 22312 b does not extend beyond the porous current collector 2211 , that is, both ends of the region of the positive electrode active material layer 22312 not covered by the insulating layer 224 in the first direction X do not extend beyond the porous current collector 2211 .

[0133] By setting the insulating layer 224 to cover the first area 22312a of the positive electrode active material layer 22312, and setting the second area 22312b to not exceed the porous current collector 2211 at both ends in the first direction X, the size of the effective area facing the positive electrode active material layer 22312 and the porous current collector 2211 in the first direction X is less than or equal to the size of the porous current collector 2211. On the one hand, the lithium plating phenomenon of the electrode assembly 22 during use can be alleviated. On the other hand, the insulating layer 224 can have a better blocking effect on the lithium metal dendrites formed at the edge of the porous current collector 2211 in the first direction X.

[0134] According to some embodiments of the present application, as shown in FIG5 and FIG8 , two insulating layers 224 are provided on the side of the positive electrode active material layer 22312 facing the porous current collector 2211 , and the two insulating layers 224 respectively cover both ends of the positive electrode active material layer 22312 .

[0135] The two insulating layers 224 respectively cover both ends of the positive electrode active material layer 22312 , that is, two insulating layers 224 are provided on the side of the positive electrode active material layer 22312 facing the porous current collector 2211 , and the two insulating layers 224 extend along the first direction X to both ends of the positive electrode active material layer 22312 .

[0136] By providing two insulating layers 224 on the side of the positive electrode active material layer 22312 facing the porous current collector 2211, the two insulating layers 224 can respectively cover the two ends of the positive electrode active material layer 22312 in the first direction X, thereby being able to block the lithium metal precipitated from the two ends of the positive electrode active material layer 22312 in the first direction X, and being able to block the lithium metal dendrites formed at the two edges of the porous current collector 2211 in the first direction X, thereby further improving the safety of the electrode assembly 22.

[0137] According to some embodiments of the present application, referring to Figures 10 and 11, Figure 10 is a cross-sectional view of the positive electrode sheet 223 of the electrode assembly 22 provided in some embodiments of the present application in other embodiments, and Figure 11 is a partial enlarged view of the positive electrode sheet 223 at point B shown in Figure 10. Along the first direction X, the insulating layer 224 extends beyond one end of the positive electrode active material layer 22312.

[0138] In which, along the first direction X, the insulating layer 224 extends out of one end of the positive electrode active material layer 22312, that is, part of the insulating layer 224 is arranged on one end of the positive electrode active material layer 22312 in the first direction X, that is, part of the insulating layer 224 in the first direction X is arranged on the positive electrode active material layer 22312, and the other part is arranged on the substrate 22311. In this embodiment, the second pole ear 2232 is the area where the substrate 22311 extends out of the insulating layer 224.

[0139] For example, in FIG10 , of the two insulating layers 224 provided on the side of the positive electrode active material layer 22312 facing the porous current collector 2211 , one insulating layer 224 extends beyond one end of the positive electrode active material layer 22312 along the first direction X, and the other insulating layer 224 is flush with one end of the positive electrode active material layer 22312 along the first direction X. Of course, the structure of the positive electrode sheet 223 is not limited to this. In other embodiments, the two insulating layers 224 may extend beyond both ends of the positive electrode active material layer 22312 along the first direction X.

[0140] By arranging the insulating layer 224 with one end extending out of the positive electrode active material layer 22312 in the first direction X, that is, the insulating layer 224 has a portion exceeding one end of the positive electrode active material layer 22312 in the first direction X, on the one hand, the insulating layer 224 can better cover one end of the positive electrode active material layer 22312, and on the other hand, the insulating layer 224 can better protect one end of the positive electrode active material layer 22312 in the first direction X, and facilitates the cutting and processing of the positive electrode sheet 223 during the manufacturing process of the electrode assembly 22.

[0141] According to some embodiments of the present application, as shown in Figure 5, along the thickness direction Y of the porous current collector, part of the insulating layer 224 overlaps with the porous current collector 2211, and the width of the overlapping part of the insulating layer 224 and the porous current collector 2211 in the first direction X is L, satisfying 1mm≤L≤3.5mm.

[0142] The width of the overlapping portion of the insulating layer 224 and the porous current collector 2211 in the first direction X is L, that is, the size of the portion of the insulating layer 224 that does not extend beyond one end of the porous current collector 2211 in the first direction X is L.

[0143] By setting the width of the overlapping portion of the insulating layer 224 and the porous current collector 2211 in the first direction X to 1 mm to 3.5 mm, on the one hand, the phenomenon that the insulating layer 224 is too ineffective in blocking lithium metal dendrites and preventing the precipitated lithium ions due to the small overlapping width between the insulating layer 224 and the porous current collector 2211 can be alleviated, and the problem of greater manufacturing difficulty due to the small overlapping width between the insulating layer 224 and the porous current collector 2211 can be alleviated. On the other hand, the phenomenon that the insulating layer 224 covers too large an area of ​​the positive electrode active material layer 22312 due to the large overlapping width between the insulating layer 224 and the porous current collector 2211 can be alleviated.

[0144] In some embodiments, as shown in FIG. 9 , along the thickness direction Y of the porous current collector, the thickness of the insulating layer 224 is D1 , satisfying D1 ≥ 10 μm.

[0145] The thickness of the insulating layer 224 is D1, and the maximum thickness of the insulating layer 224 in the thickness direction Y of the porous current collector is D1.

[0146] For example, the thickness D1 of the insulating layer 224 may be 10 μm, 11 μm, 15 μm, 20 μm, 30 μm, etc.

[0147] According to some embodiments of the present application, referring to FIG. 8 , FIG. 9 , FIG. 10 and FIG. 11 , the insulating layer 224 is connected to the positive electrode active material layer 22312 .

[0148] The insulating layer 224 can be connected to the positive electrode active material layer 22312 in various ways, such as bonding, adsorption, etc.

[0149] By connecting the insulating layer 224 to the positive electrode active material layer 22312, the insulating layer 224 can cover one end of the positive electrode active material layer 22312 in the first direction X. The electrode assembly 22 adopting this structure is beneficial to improving the covering effect of the insulating layer 224 on the positive electrode active material layer 22312 and reducing the difficulty of assembling the electrode assembly 22. On the other hand, the insulating layer 224 can also inhibit the precipitation of lithium ions in the area covered by the positive electrode active material layer 22312, thereby reducing the risk of lithium precipitation of the electrode assembly 22 during use and reducing the phenomenon of lithium ion deposition at the edge of the porous current collector 2211.

[0150] According to some embodiments of the present application, as shown in Figures 10 and 11, the positive electrode active material layer 22312 includes a first region 22312a and a second region 22312b. The first region 22312a is connected to at least one end of the second region 22312b along a first direction X. The insulating layer 224 covers the first region 22312a. Along the thickness direction Y of the porous current collector, the sum of the thicknesses of the first region 22312a and the insulating layer 224 at the same position is D2, and the thickness of the second region 22312b is D3, satisfying the condition -80 μm ≤ D2 - D3 ≤ 10 μm.

[0151] Among them, along the thickness direction Y of the porous current collector, the sum of the thickness of the first region 22312a and the insulating layer 224 at the same position is D2, that is, in the thickness direction Y of the porous current collector, the thickness of the first region 22312a and the insulating layer 224 after superposition is D2.

[0152] -80μm≤D2-D3≤10μm, that is, the dimension of the insulating layer 224 protruding from the second region 22312b in the thickness direction Y of the porous current collector is 0μm to 10μm, or the dimension of the second region 22312b protruding from the insulating layer 224 in the thickness direction Y of the porous current collector is 0μm to 80μm.

[0153] In the thickness direction Y of the porous current collector, by setting the difference between the sum of the thicknesses of the first region 22312a of the positive electrode active material layer 22312 and the insulating layer 224 at the same position and the thickness of the second region 22312b to -80μm to 10μm, the electrode assembly 22 adopting this structure can alleviate the phenomenon of excessive gap between the positive electrode active material layer 22312 and the porous current collector 2211. On the one hand, it can alleviate the phenomenon of excessive internal resistance of the electrode assembly 22 due to the excessive gap between the positive electrode active material layer 22312 and the porous current collector 2211. On the other hand, it can alleviate the risk of lithium plating in the electrode assembly 22 due to the excessive gap between the positive electrode active material layer 22312 and the porous current collector 2211.

[0154] According to some embodiments of the present application, as shown in FIG8 and FIG9 , the positive electrode active material layer 22312 includes a first region 22312a and a second region 22312b , wherein the first region 22312a is connected to at least one end of the second region 22312b along the first direction X. The insulating layer 224 covers the first region 22312a , and the thickness of the first region 22312a is less than that of the second region 22312b .

[0155] The thickness of the first region 22312a is smaller than that of the second region 22312b, that is, a region with reduced thickness is formed on the positive electrode active material layer 22312, and the insulating layer 224 is arranged in the region with reduced thickness of the positive electrode active material layer 22312.

[0156] The structure of the positive electrode sheet 223 can be various. For example, in FIG9 , in the thickness direction Y of the porous current collector, the thickness of the first region 22312a is less than that of the second region 22312b, and the surface of the first region 22312a facing away from the substrate 22311 and the surface of the second region 22312b facing away from the substrate 22311 are parallel to each other. In other words, a groove for accommodating the insulating layer 224 is formed on the surface of the positive electrode active material layer 22312 facing away from the substrate 22311, and the region where the groove is formed in the positive electrode active material layer 22312 is the first region 22312a. Of course, in some embodiments, the structure of the positive electrode sheet 223 is not limited to this. See FIG12 , which is a cross-sectional view of the positive electrode sheet 223 of the electrode assembly 22 provided in some embodiments of the present application in other embodiments. In the thickness direction Y of the porous current collector, the maximum thickness of the first region 22312a is smaller than that of the second region 22312b, and the surface of the first region 22312a facing away from the substrate 22311 and the surface of the second region 22312b facing away from the substrate 22311 are connected to each other, that is, the surface of the first region 22312a facing away from the substrate 22311 is a slope, and the surface of the first region 22312a facing away from the substrate 22311 and the surface of the second region 22312b facing away from the substrate 22311 are arranged at an acute angle, so that the surface of the positive electrode active material layer 22312 facing away from the substrate 22311 is formed with a notch for accommodating the insulating layer 224, and the area where the positive electrode active material layer 22312 forms a groove is the first region 22312a.

[0157] It should be noted that the second region 22312b of the positive electrode active material layer 22312 is connected to the first region 22312a at both ends in the first direction X. The structures of the two first regions 22312a may be the same or different. For example, in Figure 10, the surface of the first region 22312a formed at one end of the positive electrode active material layer 22312 in the first direction X away from the substrate 22311 is a plane, and the surface of the first region 22312a formed at the other end away from the substrate 22311 is an inclined surface.

[0158] By setting the thickness of the first region 22312a of the positive electrode active material layer 22312 with the insulating layer 224 to be smaller than the thickness of the second region 22312b of the positive electrode active material layer 22312, the electrode assembly 22 adopting this structure can increase the stability and reliability of the insulating layer 224 connected to the positive electrode active material layer 22312, so as to reduce the risk of the insulating layer 224 falling off during use.

[0159] According to some embodiments of the present application, referring to Figures 13 and 14, Figure 13 is a cross-sectional view of the positive electrode sheet 223 of the electrode assembly 22 provided in some embodiments of the present application in further embodiments, and Figure 14 is a partial enlarged view of the C portion of the positive electrode sheet 223 shown in Figure 13. The positive electrode active material layer 22312 includes a first region 22312a and a second region 22312b. Along the first direction X, the first region 22312a is connected to at least one end of the second region 22312b. The insulating layer 224 covers the first region 22312a. Along the thickness direction Y of the porous current collector, the surface of the first region 22312a facing the porous current collector 2211 is flush with the surface of the second region 22312b facing the porous current collector 2211.

[0160] The surface of the first region 22312a facing the porous current collector 2211 is flush with the surface of the second region 22312b facing the porous current collector 2211. That is, in the thickness direction Y of the porous current collector, the first region 22312a and the second region 22312b disposed on one side of the substrate 22311 have the same thickness. In other words, the surface of the positive electrode active material layer 22312 facing the porous current collector 2211 in the thickness direction Y of the porous current collector is a plane. In this embodiment, the region of the positive electrode active material layer 22312 covered by the insulating layer 224 is the first region 22312a.

[0161] By setting the surface of the first region 22312a of the positive electrode active material layer 22312 with the insulating layer 224 facing the porous current collector 2211 to be flush with the surface of the second region 22312b of the positive electrode active material layer 22312 facing the porous current collector 2211, that is, the surface of the positive electrode active material layer 22312 facing the porous current collector 2211 in the thickness direction Y of the porous current collector is flat, and the insulating layer 224 is connected to the surface of the positive electrode active material layer 22312 facing the porous current collector 2211 to cover the first region 22312a of the positive electrode active material layer 22312. This structure makes it easy to connect the insulating layer 224 to the positive electrode active material layer 22312, which is beneficial to reducing processing difficulty and improving production efficiency.

[0162] According to some embodiments of the present application, please refer to Figures 15 and 16. Figure 15 is a partial cross-sectional view of an electrode assembly 22 provided in other embodiments of the present application, and Figure 16 is a partial enlarged view of a portion D of the electrode assembly 22 shown in Figure 15. The electrode assembly 22 may further include a separator 222, which is disposed between the negative electrode sheet 221 and the positive electrode sheet 223 to separate the negative electrode sheet 221 from the positive electrode sheet 223. An insulating layer 224 is connected to the surface of the separator 222 facing the positive electrode active material layer 22312.

[0163] The insulating layer 224 is connected to the surface of the separator 222 facing the positive electrode active material layer 22312. That is, the insulating layer 224 is located between the separator 222 and the active material layer of the positive electrode tab 223 in the thickness direction Y of the porous current collector, and is connected to the separator 222 so that the insulating layer 224 covers one end of the positive electrode active material layer 22312. In this embodiment, the second tab 2232 is the region where the substrate 22311 extends beyond the positive electrode active material layer 22312 in the first direction X.

[0164] For example, the insulating layer 224 may be connected to the isolation film 222 by bonding, adsorption, or other connection methods.

[0165] For example, the material of the isolation film may be polypropylene (PP) or polyethylene (PE).

[0166] The electrode assembly 22 is also provided with a separator 222, which can separate the positive electrode sheet 223 from the negative electrode sheet 221, thereby reducing the risk of short circuit between the positive electrode sheet 223 and the negative electrode sheet 221. In addition, an insulating layer 224 is connected to the surface of the separator 222 facing the positive electrode active material layer 22312, so that the insulating layer 224 covers one end of the positive electrode active material layer 22312. This structure helps to reduce the difficulty of assembling the insulating layer 224.

[0167] According to some embodiments of the present application, as shown in FIG6 , the main body 2231 includes a substrate 22311 and a positive electrode active material layer 22312. The second tab 2232 is connected to the substrate 22311. The positive electrode active material layer 22312 is disposed on a side of the substrate 22311 facing the porous current collector 2211 in the thickness direction Y of the porous current collector. Along the first direction X, both ends of the positive electrode active material layer 22312 do not extend beyond the porous current collector 2211. Along the first direction X, at least one end of the positive electrode active material layer 22312 is connected to the insulating layer 224, and the insulating layer 224 extends beyond one end of the porous current collector 2211.

[0168] The main body 2231 includes a substrate 22311, a positive electrode active material layer 22312, and an insulating layer 224. Specifically, the main body 2231 is composed of the substrate 22311, the positive electrode active material layer 22312, and the insulating layer 224 disposed on one side of the substrate 22311. The insulating layer 224 is connected to one end of the positive electrode active material layer 22312 in the first direction X, so that the positive electrode active material layer 22312 and the insulating layer 224 can cooperate to cover and compress the porous current collector 2211 of the negative electrode plate 221. Specifically, the substrate 22311 is provided with the positive electrode active material layer 22312 on the side facing the porous current collector 2211, and the insulating layer 224 is arranged along the first direction X. In this embodiment, the second tab 2232 is the region where the substrate 22311 extends beyond the insulating layer 224.

[0169] Along the first direction X, both ends of the positive electrode active material layer 22312 do not extend beyond the porous current collector 2211. That is, in the first direction X, both ends of the porous current collector 2211 may extend beyond the positive electrode active material layer 22312, or one end of the porous current collector 2211 may extend beyond the positive electrode active material layer 22312 and the other end may be flush with one end of the positive electrode active material layer 22312. Alternatively, both ends of the porous current collector 2211 may be flush with both ends of the positive electrode active material layer 22312. For example, in FIG6 , both ends of the porous current collector 2211 in the first direction X extend beyond the positive electrode active material layer 22312.

[0170] Along the first direction X, the insulating layer 224 extends beyond one end of the porous current collector 2211, that is, in the first direction X, the insulating layer 224 extends from one end close to the positive electrode active material layer 22312 toward a direction away from the positive electrode active material layer 22312, and extends beyond one end of the porous current collector 2211, so that the projection of the edge of the porous current collector 2211 in the thickness direction Y of the porous current collector is located within the insulating layer 224.

[0171] For example, in Figure 6, along the thickness direction Y of the porous current collector, the thickness of the insulating layer 224 is the same as the thickness of the positive electrode active material layer 22312, so that the surface of the insulating layer 224 facing the porous current collector 2211 is flush with the surface of the positive electrode active material layer 22312 facing the porous current collector 2211.

[0172] By setting the two ends of the positive electrode active material layer 22312 in the first direction X so as not to extend beyond the porous current collector 2211, connecting the insulating layer 224 to at least one end of the positive electrode active material layer 22312 in the first direction X, and the insulating layer 224 extends beyond one end of the porous current collector 2211 in the first direction X, so that the insulating layer 224 can provide a binding force to the edge of the porous current collector 2211, the electrode assembly 22 with this structure can effectively reduce the risk of lithium plating of the electrode assembly 22 during use while ensuring that the entire porous current collector 2211 is subjected to the pressure of the main body 2231.

[0173] In some embodiments, referring to FIG. 6 , along the first direction X, both ends of the positive electrode active material layer 22312 are connected to the insulating layer 224 .

[0174] Both ends of the positive electrode active material layer 22312 are connected to the insulating layer 224 , and the two insulating layers 224 extend beyond both ends of the porous current collector 2211 .

[0175] By connecting the insulating layer 224 at both ends of the positive electrode active material layer 22312 along the first direction X, the two insulating layers 224 can extend out of the two ends of the porous current collector 2211 along the first direction X, thereby providing binding force to both edges of the porous current collector 2211 in the first direction X, so as to alleviate the phenomenon of lithium metal deposition at the edge of the porous current collector 2211 to form dendrites, and thus effectively inhibit the growth of lithium metal dendrites, which is beneficial to reducing the risk of short circuit of the electrode assembly 22, so as to improve the safety and performance of the electrode assembly 22.

[0176] According to some embodiments of the present application, the elastic modulus of the insulating layer 224 is E, which satisfies E≥1 GPa. The value of the elastic modulus of the insulating layer 224 can be found in national standards and will not be repeated here.

[0177] An insulating layer 224 with an elastic modulus greater than or equal to 1 GPa is used, so that the insulating layer 224 has good strength and toughness. On the one hand, it can effectively reduce the phenomenon of damage to the insulating layer 224 during use, thereby improving the service life of the electrode assembly 22. On the other hand, it can play a good blocking role on lithium metal dendrites, which is beneficial to reduce the phenomenon of the insulating layer 224 being punctured by lithium metal dendrites, thereby effectively reducing the risk of use of the battery cell 20.

[0178] In some embodiments, the insulating layer 224 is an insulating tape or an insulating coating.

[0179] Among them, if the insulating layer 224 is an insulating tape, the insulating layer 224 can be a blue tape or a green tape, etc., and the insulating layer 224 is connected to the positive electrode active material layer 22312 or the isolation membrane 222 by bonding; if the insulating layer 224 is an insulating coating, the insulating layer 224 can be an epoxy resin insulating paint or an alumina ceramic coating, etc., and the insulating layer 224 is connected to the positive electrode active material layer 22312 or the isolation membrane 222 by coating. Its elastic modulus can be shown in the table below.

[0180] Material: blue glue, green glue, epoxy resin, insulating paint, alumina ceramic coating, elastic modulus / GPa≥1≥1≥2≥1

[0181] An insulating tape or insulating coating is used as the insulating layer 224 to cover one end of the positive electrode active material layer 22312 in the first direction X. The insulating layer 224 of this structure only needs to be bonded or coated on the side of the positive electrode active material layer 22312 facing the porous current collector 2211, which facilitates the assembly of the electrode assembly 22 and is beneficial to improving the production efficiency of the electrode assembly 22.

[0182] According to some embodiments of the present application, referring to FIG. 5 , FIG. 6 and FIG. 7 , along the first direction X, at least one end of the main body 2231 extends beyond the porous current collector 2211 .

[0183] In which, at least one end of the main body 2231 extends beyond the porous collector 2211, that is, one end of the main body 2231 in the first direction X can extend beyond the porous collector 2211, and the other end can be flush with one end of the porous collector 2211, or both ends of the main body 2231 in the first direction X can extend beyond the porous collector 2211.

[0184] For example, in FIG. 5 , FIG. 6 and FIG. 7 , both ends of the main body 2231 are structures extending beyond the porous current collector 2211 .

[0185] By setting at least one end of the main body 2231 in the first direction X to extend beyond the porous current collector 2211, it is ensured that the porous current collector 2211 can be subjected to the pressure of the main body 2231, so that the porous current collector 2211 can be subjected to better expansion restraint force, thereby effectively alleviating the phenomenon of unlimited growth of lithium metal dendrites in the porous current collector 2211.

[0186] According to some embodiments of the present application, please refer to FIG17 , which is a partial cross-sectional view of an electrode assembly 22 provided in yet other embodiments of the present application. Along the first direction X, both ends of the main body 2231 are flush with both ends of the porous current collector 2211 .

[0187] By setting the two ends of the main body 2231 in the first direction X to be flush with the porous current collector 2211, the electrode assembly 22 with this structure can effectively reduce the waste of the positive electrode active material layer 22312 while ensuring that the entire porous current collector 2211 is subjected to the pressure of the main body 2231, which is beneficial to reducing the manufacturing cost of the electrode assembly 22 and saving the space occupied by the electrode assembly 22.

[0188] According to some embodiments of the present application, as shown in FIG. 5 , along the thickness direction Y of the porous current collector, the maximum thickness of the first electrode tab 2212 is less than the thickness of the porous current collector 2211 .

[0189] The maximum thickness of the first electrode tab 2212 is smaller than the thickness of the porous current collector 2211 , that is, the thickness of the first electrode tab 2212 at any position in the thickness direction Y of the porous current collector is smaller than the thickness of the porous current collector 2211 .

[0190] By setting the maximum thickness of the first pole tab 2212 in the thickness direction Y of the porous current collector to be smaller than the thickness of the porous current collector 2211, on the one hand, it is convenient to subsequently assemble and connect the first pole tab 2212 with other components. On the other hand, during the production process of the electrode assembly 22, when the two ends of the porous current collector 2211 of the negative electrode plate 221 in the first direction X are set so as not to exceed the main body 2231 of the positive electrode plate 223, it is convenient to effectively distinguish the porous current collector 2211 and the first pole tab 2212, so as to improve the manufacturing accuracy of the electrode assembly 22.

[0191] According to some embodiments of the present application, please continue to refer to FIG5 , the porous current collector 2211 and the first electrode tab 2212 are an integrated structure, and the first electrode tab 2212 is connected to one end of the porous current collector 2211 in the first direction X. The first electrode tab 2212 includes a main body section 2212a and a transition section 2212b. Along the first direction X, the transition section 2212b is connected between the main body section 2212a and the porous current collector 2211, and the thickness of the transition section 2212b in the thickness direction Y of the porous current collector gradually increases from the end close to the main body section 2212a to the end close to the porous current collector 2211.

[0192] The first electrode tab 2212 is formed by rolling or other processes at one end of the negative electrode sheet 221 in the first direction X. This allows the negative electrode sheet 221 to be formed with a porous current collector 2211 and a first electrode tab 2212 of relatively small thickness that protrudes from one end of the porous current collector 2211 in the first direction X. This means that the first electrode tab 2212 is formed with a main section 2212a and a transition section 2212b connecting the main section 2212a and the porous current collector 2211. The main section 2212a is used to connect to the negative electrode terminal. In this embodiment, it is sufficient to set the portion of the negative electrode sheet 221 that is not compressed by rolling (i.e., the porous current collector 2211) so as not to extend beyond the main section 2231 of the positive electrode sheet 223.

[0193] By setting the porous current collector 2211 and the first pole ear 2212 as an integrally formed structure, the first pole ear 2212 is formed with a main section 2212a and a transition section 2212b connected between the porous current collector 2211 and the main section 2212a, and the thickness of the transition section 2212b in the thickness direction Y of the porous current collector gradually increases from the end close to the main section 2212a to the end close to the porous current collector 2211, thereby achieving the first pole ear 2212 protruding from one end of the porous current collector 2211. The negative electrode sheet 221 with this structure can effectively improve the structural strength of the first pole ear 2212 and can effectively improve the connection strength between the first pole ear 2212 and the porous current collector 2211.

[0194] According to some embodiments of the present application, please refer to Figures 18 and 19. Figure 18 is a partial cross-sectional view of an electrode assembly 22 provided in still further embodiments of the present application, and Figure 19 is a partial enlarged view of a portion E of the electrode assembly 22 shown in Figure 18. The porous current collector 2211 and the first electrode tab 2212 are separate structures. The first electrode tab 2212 is connected to one side of the porous current collector 2211 in the thickness direction Y of the porous current collector, and the first electrode tab 2212 protrudes from one end of the porous current collector 2211 along the first direction X.

[0195] The first electrode tab 2212 and the porous current collector 2211 are separate components, that is, the first electrode tab 2212 and the porous current collector 2211 are independent components. The first electrode tab 2212 is connected to one side of the porous current collector 2211 in the thickness direction Y of the porous current collector and extends out of one end of the porous current collector 2211 along the first direction X. In this embodiment, the first electrode tab 2212 and the porous current collector 2211 have an overlapping area in the thickness direction Y of the porous current collector, so that the porous current collector 2211 only needs to be arranged in the first direction X so as not to exceed the main body 2231 of the positive electrode sheet 223.

[0196] Illustratively, the first electrode tab 2212 is welded to the porous current collector 2211 to form a weld mark 2213 .

[0197] Of course, in some embodiments, as shown in FIG19 , in an embodiment where the first electrode tab 2212 is welded to the porous current collector 2211, the negative electrode sheet 221 may further be provided with a protective adhesive 2214. The protective adhesive 2214 is provided on the side of the weld mark 2213 facing the separator 222 in the thickness direction Y of the porous current collector and covers the weld mark 2213. It should be noted that in other embodiments, the protective adhesive 2214 may not be provided on the weld mark 2213 of the negative electrode sheet 221.

[0198] For example, the material of the protective glue 2214 can be rubber, plastic, or silicone.

[0199] By setting the porous current collector 2211 and the first pole ear 2212 as a split structure, and connecting the first pole ear 2212 to one side of the porous current collector 2211 in the thickness direction Y of the porous current collector and then protruding from one end of the porous current collector 2211 along the first direction X, so as to achieve the first pole ear 2212 protruding from one end of the porous current collector 2211, the manufacturing difficulty of the negative electrode plate 221 of this structure is relatively low, which is conducive to improving the production efficiency of the electrode assembly 22.

[0200] According to some embodiments of the present application, as shown in FIG. 5 , along the thickness direction Y of the porous current collector, the thickness of the second electrode tab 2232 is less than the thickness of the main body 2231 .

[0201] The second electrode tab 2232 and the substrate 22311 can be an integral structure or a separate structure. If the second electrode tab 2232 and the substrate 22311 are an integral structure, that is, the second electrode tab 2232 is the region of the substrate 22311 extending beyond the positive electrode active material layer 22312 and the insulating layer 224 in the first direction X. If the second electrode tab 2232 and the substrate 22311 are a separate structure, the second electrode tab 2232 can be connected to one end of the substrate 22311 in the first direction X by welding or other means, so that the second electrode tab 2232 protrudes from the end of the main body 2231 in the first direction X. For example, in FIG. 5 , the second electrode tab 2232 and the substrate 22311 are an integral structure.

[0202] By setting the thickness of the second pole tab 2232 in the thickness direction Y of the porous current collector to be smaller than the thickness of the main body 2231, on the one hand, it is convenient to subsequently assemble and connect the second pole tab 2232 with other components. On the other hand, during the production process of the electrode assembly 22, when the two ends of the porous current collector 2211 of the negative electrode sheet 221 in the first direction X are set so as not to exceed the main body 2231 of the positive electrode sheet 223, it is convenient to effectively distinguish the main body 2231 and the second pole tab 2232, so as to improve the manufacturing accuracy of the electrode assembly 22.

[0203] According to some embodiments of the present application, as shown in FIG. 4 and FIG. 5 , the electrode assembly 22 is a wound electrode assembly 22 , and the first direction X is consistent with the winding axis direction of the electrode assembly 22 .

[0204] Among them, the electrode assembly 22 is a winding structure, so that the first direction X is the extension direction of the winding axis of the electrode assembly 22, that is, the plane where the winding direction of the electrode assembly 22 is located is perpendicular to the first direction X, and the thickness direction Y of the porous current collector is the radial direction of the electrode assembly 22.

[0205] By setting the electrode assembly 22 as a winding structure, and the first direction X is consistent with the winding axis direction of the electrode assembly 22, the electrode assembly 22 with this structure is easy to manufacture and produce, which is beneficial to reduce the misalignment of the positive electrode plate 223 and the negative electrode plate 221. On the other hand, it is only necessary to set the two ends of the porous current collector 2211 of the negative electrode plate 221 in the first direction X to the positive electrode active material layer 22312 that does not exceed the positive electrode plate 223 to ensure that the entire porous current collector 2211 is subjected to the pressure of the main body 2231, thereby effectively suppressing the growth of lithium metal dendrites of the porous current collector 2211.

[0206] According to some embodiments of the present application, the porous current collector 2211 is made of foam metal.

[0207] Exemplarily, the porous current collector 2211 is made of copper foam. Of course, in other embodiments, the porous current collector 2211 can also be made of nickel foam, etc. Using copper foam as the material for the porous current collector 2211 allows the porous current collector 2211 to have better electrical conductivity, thereby helping to reduce the internal resistance of the electrode assembly 22 having such a negative electrode plate 221, thereby improving the performance of the battery cell 20.

[0208] The porous current collector 2211 made of foam metal enables the porous current collector 2211 to have the function of directly reacting with lithium ions to realize the input or output of electrical energy of the negative electrode plate 221, and the porous current collector 2211 with this structure can realize the deposition of lithium ions inside the porous current collector 2211, which is beneficial to reduce the risk of lithium metal deposition on the surface of the porous current collector 2211.

[0209] In some embodiments, as shown in FIG. 3 and FIG. 4 , the electrode assembly 22 is a cylindrical structure.

[0210] The central axis of the cylindrical electrode assembly 22 extends along the first direction X.

[0211] By configuring the electrode assembly 22 as a cylindrical structure, the expansion force generated by the cylindrical electrode assembly 22 during use is smaller, so that the electrode assembly 22 is suitable for the porous current collector 2211 made of foam metal.

[0212] According to some embodiments of the present application, a battery cell 20 is further provided. The battery cell 20 includes a housing 21 and an electrode assembly 22 according to any of the above solutions. The electrode assembly 22 is accommodated in the housing 21 .

[0213] According to some embodiments of the present application, a battery 100 is further provided. The battery 100 includes a battery cell 20 according to any of the above solutions.

[0214] According to some embodiments of the present application, an electric device is further provided. The electric device includes a battery cell 20 according to any of the above solutions, and the battery cell 20 is used to provide electric energy to the electric device.

[0215] The power-consuming device may be any of the aforementioned devices or systems using the battery cell 20 .

[0216] According to some embodiments of the present application, referring to Figures 3 to 5 and Figures 8 to 9, the present application provides an electrode assembly 22, which includes a negative electrode sheet 221, a positive electrode sheet 223, and a separator 222. The separator 222 is disposed between the negative electrode sheet 221 and the positive electrode sheet 223 to separate the negative electrode sheet 221 and the positive electrode sheet 223. The negative electrode plate 221 includes a porous current collector 2211 and a first electrode tab 2212 connected to one end of the porous current collector 2211 along a first direction X. The first electrode tab 2212 and the porous current collector 2211 are an integrated structure. The first electrode tab 2212 includes a main section 2212a and a transition section 2212b. Along the first direction X, the transition section 2212b is connected between the main section 2212a and the porous current collector 2211, and the thickness of the transition section 2212b in the thickness direction Y of the porous current collector gradually increases from one end close to the main section 2212a to the end close to the porous current collector 2211. The positive electrode sheet 223 includes a main body 2231 and a second tab 2232 connected to one end of the main body 2231 along a first direction X. The main body 2231 and the porous current collector 2211 are stacked along the thickness direction Y of the porous current collector. Both ends of the main body 2231 extend beyond the porous current collector 2211 along the first direction X. The first direction X is perpendicular to the thickness direction Y of the porous current collector. The main body 2231 includes a substrate 22311 and a positive active material layer 22312 coated on both sides of the substrate 22311 along the thickness direction Y of the porous current collector. Two insulating layers 224 are provided on the side of the positive active material layer 22312 facing the porous current collector 2211. The two insulating layers 224 respectively cover the two ends of the positive active material layer 22312 in the first direction X. The second electrode tab 2232 and the substrate 22311 are integrally formed. The second electrode tab 2232 is the region of the substrate 22311 extending in the first direction X beyond the positive electrode active material layer 22312 and the insulating layer 224. The positive electrode active material layer 22312 includes a first region 22312a and a second region 22312b. Along the first direction X, both ends of the second region 22312b are connected to the first region 22312a. The two insulating layers 224 respectively cover the two first regions 22312a. Along the first direction X, the second region 22312b does not extend beyond the porous current collector 2211. The insulating layer 224 is connected to the first region 22312a of the positive electrode active material layer 22312. The thickness of the first region 22312a is less than that of the second region 22312b. Along the thickness direction Y of the porous current collector, the insulating layer 224 partially overlaps with the porous current collector 2211 . The width of the overlapping portion of the insulating layer 224 and the porous current collector 2211 in the first direction X is L, satisfying 1 mm ≤ L ≤ 3.5 mm.Along the thickness direction Y of the porous current collector, the sum of the thicknesses of the first region 22312a and the insulating layer 224 at the same position is D2, and the thickness of the second region 22312b is D3, satisfying -80 μm ≤ D2 - D3 ≤ 10 μm.

[0217] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0218] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Persons skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. An electrode assembly comprising: A negative electrode plate, comprising a porous current collector and a first electrode tab connected to at least one end of the porous current collector; as well as The positive electrode sheet includes a main body and a second electrode tab connected to at least one end of the main body. The main body and the porous current collector are stacked along the thickness direction of the porous current collector. Along the first direction, both ends of the porous current collector do not exceed the main body. The first direction is perpendicular to the thickness direction of the porous current collector.

2. The electrode assembly according to claim 1, wherein The main body comprises: a substrate, wherein the second tab is connected to the substrate; a positive electrode active material layer, disposed on a side of the substrate facing the porous current collector in the thickness direction of the porous current collector, wherein both ends of the porous current collector do not extend beyond the positive electrode active material layer along the first direction; Wherein, an insulating layer is provided on the side of the positive electrode active material layer facing the porous current collector, and the insulating layer covers one end of the positive electrode active material layer.

3. The electrode assembly according to claim 2, wherein: The positive electrode active material layer includes a first region and a second region, and along the first direction, the first region is connected to at least one end of the second region; The insulating layer covers the first region, and along the first direction, the second region does not exceed the porous current collector.

4. The electrode assembly according to claim 2 or 3, wherein: Two insulating layers are provided on the side of the positive electrode active material layer facing the porous current collector, and the two insulating layers respectively cover both ends of the positive electrode active material layer.

5. The electrode assembly according to any one of claims 2 to 4, wherein: Along the first direction, the insulating layer extends beyond one end of the positive electrode active material layer.

6. The electrode assembly according to any one of claims 2 to 5, wherein: Along the thickness direction of the porous current collector, part of the insulating layer overlaps with the porous current collector, and a width L of the overlapping part of the insulating layer and the porous current collector in the first direction satisfies 1 mm ≤ L ≤ 3.5 mm.

7. The electrode assembly according to any one of claims 2 to 6, wherein: The insulating layer is connected to the positive electrode active material layer.

8. The electrode assembly according to claim 7, wherein: The positive electrode active material layer includes a first region and a second region, and along the first direction, the first region is connected to at least one end of the second region; The insulating layer covers the first region, and along the thickness direction of the porous current collector, the sum of the thickness of the first region and the insulating layer at the same position is D2, and the thickness of the second region is D3, satisfying -80μm≤D2-D3≤10μm.

9. The electrode assembly according to claim 7 or 8, wherein: The positive electrode active material layer includes a first region and a second region, and along the first direction, the first region is connected to at least one end of the second region; The insulating layer covers the first region, and the thickness of the first region is smaller than the thickness of the second region.

10. The electrode assembly according to claim 7 or 8, wherein: The positive electrode active material layer includes a first region and a second region, and along the first direction, the first region is connected to at least one end of the second region; The insulating layer covers the first region, and along the thickness direction of the porous current collector, the surface of the first region facing the porous current collector is flush with the surface of the second region facing the porous current collector.

11. The electrode assembly according to any one of claims 2 to 6, wherein: The electrode assembly further comprises: A separator, disposed between the negative electrode sheet and the positive electrode sheet to separate the negative electrode sheet from the positive electrode sheet; The insulating layer is connected to the surface of the separator facing the positive electrode active material layer.

12. The electrode assembly according to claim 1, wherein The main body comprises: a substrate, wherein the second tab is connected to the substrate; a positive electrode active material layer disposed on a side of the substrate facing the porous current collector in the thickness direction of the porous current collector, wherein both ends of the positive electrode active material layer do not extend beyond the porous current collector along the first direction; Wherein, along the first direction, at least one end of the positive electrode active material layer is connected to an insulating layer, and the insulating layer extends beyond one end of the porous current collector.

13. The electrode assembly according to claim 12, wherein: Along the first direction, both ends of the positive electrode active material layer are connected to the insulating layer.

14. The electrode assembly according to any one of claims 2 to 13, wherein: The elastic modulus of the insulating layer is E, which satisfies E≥1 GPa.

15. The electrode assembly according to any one of claims 2 to 14, wherein: The insulating layer is an insulating tape or an insulating coating.

16. The electrode assembly according to any one of claims 1 to 15, wherein: Along the first direction, at least one end of the main body extends beyond the porous current collector.

17. The electrode assembly according to any one of claims 1 to 15, wherein: Along the first direction, two ends of the main body are flush with two ends of the porous current collector.

18. The electrode assembly according to any one of claims 1 to 17, wherein: Along the thickness direction of the porous current collector, the maximum thickness of the first electrode tab is smaller than the thickness of the porous current collector.

19. The electrode assembly according to claim 18, wherein The porous current collector and the first electrode tab are an integrated structure, and the first electrode tab is connected to one end of the porous current collector in the first direction; Among them, the first electrode tab includes a main section and a transition section. Along the first direction, the transition section is connected between the main section and the porous current collector, and the thickness of the transition section in the thickness direction of the porous current collector gradually increases from one end close to the main section to the other end close to the porous current collector.

20. The electrode assembly according to claim 18, wherein The porous current collector and the first electrode tab are split structures. The first electrode tab is connected to one side of the porous current collector in the thickness direction of the porous current collector, and the first electrode tab protrudes from one end of the porous current collector along the first direction.

21. The electrode assembly according to any one of claims 1 to 20, wherein: Along the thickness direction of the porous current collector, the thickness of the second electrode tab is smaller than the thickness of the main body.

22. The electrode assembly according to any one of claims 1 to 21, wherein: The electrode assembly is a wound electrode assembly, and the first direction is consistent with the winding axis direction of the electrode assembly.

23. The electrode assembly according to any one of claims 1 to 22, wherein: The porous current collector is made of foam metal.

24. The electrode assembly according to claim 23, wherein The electrode assembly is a cylindrical structure.

25. A battery cell comprising: shell; as well as The electrode assembly according to any one of claims 1 to 24, wherein the electrode assembly is housed in the housing.

26. A battery comprising the battery cell according to claim 25.

27. An electrical device comprising the battery cell according to claim 25.

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