Electrode assembly, battery, and electric device

Abstract

The application discloses an electrode assembly, a battery and a power utilization device. The electrode assembly comprises a separator film, a first electrode sheet and a second electrode sheet. The first electrode sheet comprises a first current collector, a reinforcing layer and a first active material layer. The first current collector comprises a first main body part and a first tab. The first tab is arranged on one side of the first main body part along the width direction of the first electrode sheet. The first active material layer is arranged on the surface of the first main body part. The reinforcing layer covers part of the first tab and part of the first active material layer. The thickness D2 of the reinforcing layer satisfies the following condition: D1<=D2<=D1+D3. D1 is the thickness of the first main body part, and D3 is the thickness of the first active material layer. The first electrode sheet, the separator film and the second electrode sheet are arranged in a winding manner along the winding direction. The application can improve the reliability of the battery without affecting the energy density of the battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more particularly to an electrode assembly, a battery, and an electrical device. Background Technology

[0002] With the rapid development of the new energy industry, the application of secondary batteries in electric vehicles, electric bicycles, power tools and other fields has become a trend.

[0003] Improving battery reliability without affecting battery energy density has become a research focus for industry professionals. Summary of the Invention

[0004] This application provides an electrode assembly, a battery, and an electrical device that can improve battery reliability without affecting battery energy density.

[0005] In a first aspect, embodiments of this application provide an electrode assembly, which includes a separator, a first electrode, and a second electrode. The first electrode includes a first current collector, a reinforcing layer, and a first active material layer. The first current collector includes a first main body and a first tab. The first tab is disposed on one side of the first main body along the width direction of the first electrode. The first active material layer is disposed on the surface of the first main body. The reinforcing layer covers a portion of the first tab and a portion of the first active material layer. The thickness D2 of the reinforcing layer satisfies the following condition: D1≤D2≤D1+D3, where D1 is the thickness of the first main body and D3 is the thickness of the first active material layer. The first electrode, the separator, and the second electrode are wound together along the winding direction.

[0006] In the above scheme, by covering part of the first tab and part of the first active material layer with the reinforcement layer, and D1≤D2, the reinforcement layer has sufficient structural strength to protect the tab from being easily folded, reducing the risk of tab breakage, falling off or overlapping; at the same time, by D2≤D1+D3, the reinforcement layer does not occupy too much space inside the battery, thereby improving the reliability of the battery without affecting the battery energy density.

[0007] In some embodiments, the reinforcing layer is a porous ion-conducting layer, which includes a first region located on the first tab and a second region located on the first active material layer; the average porosity P1 of the first region and the average porosity P2 of the second region satisfy: 5% ≤ P1 < P2 ≤ 50%, and 10% ≤ P2 - P1 ≤ 45%.

[0008] In the above scheme, by setting the reinforcement layer as a porous ion-conducting layer and forming a porosity gradient between the tab side and the active material layer side, the mechanical protection strength of the reinforcement layer for the tab is guaranteed to a certain extent, while reducing the obstruction of the reinforcement layer to ion transport.

[0009] In some embodiments, the reinforcing layer comprises a shape memory polymer, wherein the shrinkage rate S of the shape memory polymer at a temperature of 40°C to 75°C satisfies 3% ≤ S ≤ 12%.

[0010] In the above scheme, by limiting the shrinkage rate within a suitable range, the reinforcing layer can generate sufficient shrinkage stress to resist peeling, and to a certain extent prevents the shrinkage stress from exceeding the bonding strength between the reinforcing layer and the current collector interface, or from excessively compressing the edge of the first active material layer to cause local overcharging or lithium plating.

[0011] In some embodiments, the width of the protrusion of one side edge of the first electrode in the width direction relative to the same side edge of the second electrode in the width direction is L; a plurality of micro-protrusions are constructed on the surface of the reinforcing layer away from the first current collector, and the micro-protrusions extend along the length direction of the first electrode; the height h of the micro-protrusions satisfies: 1μm ≤ h ≤ min( D2 - D1 , 0.5L ), and h ≥ 0.1×(D2 - D1).

[0012] In the above solution, by limiting the micro-protrusions to a suitable range, the risk of reinforcement layer peeling can be reduced, and short circuits can be avoided to a certain extent.

[0013] In some embodiments, in the direction from the first electrode tab to the first main body, the widths of the first electrode tab and the reinforcing layer gradually increase along the length direction.

[0014] In the above solution, by setting the width of the first electrode tab and the reinforcing layer to gradually change, not only can the connection stability between the first electrode tab and the first main body be increased, but the risk of electrode tab flipping can also be further reduced.

[0015] In some embodiments, the electrode assembly includes an inner ring region and an outer ring region. The first electrode sheet is wound with a total of N turns along the winding direction. From the inside to the outside of the winding direction, the first turn to the k1th turn of the first electrode sheet is the inner ring region, and the k2th turn to the Nth turn of the first electrode sheet is the outer ring region. Here, k1 is 30% of the total number of turns N, k2 is 70% of the total number of turns N, and N, k1, and k2 are all positive integers. There are multiple first electrode tabs, with some first electrode tabs located in the inner ring region and some first electrode tabs located in the outer ring region. At least one side of the first electrode tabs located in the inner ring region is provided with a reinforcing layer. Each of the multiple first electrodes has a reinforcing layer on one side, with the thickness of the multiple reinforcing layers gradually decreasing in the direction from the inner ring area to the outer ring area.

[0016] In the above scheme, by setting a reinforcing layer in the inner ring area where the bending stress is the greatest, the first tab, which is most prone to flipping, can be prevented from flipping to a certain extent. Moreover, the reinforcing layer decreases as the number of rings increases, which can reduce the risk of the first tab flipping and further save the internal space of the battery, thereby improving the energy density of the battery.

[0017] In some embodiments, the number of first tabs is m, and a reinforcing layer is provided on one side of each of the n first tabs; wherein, 1≤n≤m / 3, and m and n are both positive integers.

[0018] In the above scheme, by limiting the correspondence between the number of reinforcing layers and the number of first tabs within a suitable range, the reliability of the battery can be improved without affecting the battery manufacturing efficiency.

[0019] In some embodiments, the width of one side edge of the first electrode sheet protruding relative to the same side edge of the second electrode sheet in the width direction is L; the width of the overlapping portion of the reinforcing layer and the first main body in the width direction is less than or equal to L.

[0020] In the above scheme, by setting the width of the overlapping portion of the reinforcing layer and the first main body to be less than or equal to the width of the first electrode extending beyond the second electrode, the first active material layer of the first electrode extends beyond the second active material layer of the second electrode in the width direction, thereby reducing lithium plating.

[0021] In some embodiments, the width H2 of the reinforcing layer along the width direction satisfies: 2 / 5H1≤H2≤3 / 5H1; where H1 is the width of the first electrode tab along the width direction.

[0022] In the above solution, by limiting the ratio of the width of the reinforcing layer to the width of the first electrode tab within a suitable range, the risk of the first electrode tab flipping over can be reduced without affecting the welding of the electrode tab.

[0023] In some embodiments, the surface of the first electrode tab has a solder mark, and the solder mark and the reinforcing layer are spaced apart along the width direction; the distance H3 between the side of the solder mark facing the first main body and the first main body satisfies: H3≥1 / 2H1; where H1 is the width of the first electrode tab along the width direction.

[0024] In the above scheme, by setting the solder stamp and the reinforcing layer at intervals along the width direction, the welding of the first electrode tab will not affect or damage the reinforcing layer, thus ensuring the integrity of the reinforcing layer to a certain extent; by limiting the ratio of H3 to H1 within a suitable range, it is easy to weld between multiple layers of first electrode tabs and it is not easy to cause the first electrode tab to tear.

[0025] Secondly, embodiments of this application also provide a battery including the electrode assembly of any of the above embodiments.

[0026] Thirdly, embodiments of this application also provide an electrical device, including the aforementioned battery.

[0027] The electrical equipment provided in this application embodiment has the same technical effect as the battery provided in the above embodiment, and will not be described again here. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of the electrode assembly in a wound state according to some embodiments of this application; Figure 2 This is a schematic diagram of the first electrode sheet in an unfolded state according to some embodiments of this application; Figure 3 for Figure 2 An enlarged schematic diagram of part A in the middle; Figure 4 for Figure 3 A schematic cross-sectional view along the B-B' section. Figure 5 This is a partial structural schematic diagram of the first electrode sheet in some embodiments of this application; Figure 6 This is a schematic cross-sectional view of the first electrode sheet in some embodiments of this application; Figure 7 This is a partial structural schematic diagram of the first electrode sheet in some other embodiments of this application; Figure 8 This is a cross-sectional schematic diagram of the reinforcing layer and micro-protrusions in some embodiments of this application; Figure 9 This is a partial structural schematic diagram of the first electrode sheet in some embodiments of this application.

[0030] Explanation of reference numerals in the attached figures: 100. Electrode assembly; 10. First electrode; 11. First current collector; 111. First main body; 112. First tab; 113. First region; 114. Second region; 115. Micro-protrusion; 1151. Root; 1152. Top; 1153. Sidewall; 116. First side edge; 117. Second side edge; 118. Solder mark; 12. Reinforcing layer; 121. First side edge; 122. Second side edge; 13. First active material layer; 20. Second electrode; 30. Separating membrane; 41. Inner ring region; 42. Outer ring region; X, length direction; Y, width direction. Detailed Implementation

[0031] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0032] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0033] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0034] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application depending on the specific circumstances.

[0035] In this application, "multiple" means two or more (including two).

[0036] Figure 1 This is a schematic diagram of the structure of the electrode assembly in a wound state according to some embodiments of this application; Figure 2 This is a schematic diagram of the first electrode sheet in an unfolded state according to some embodiments of this application; Figure 3 for Figure 2 An enlarged schematic diagram of part A in the middle; Figure 4 for Figure 3 A schematic diagram of the cross section along the B-B' axis.

[0037] Please refer to the following: Figures 1-4 In a first aspect, embodiments of this application provide an electrode assembly 100, which includes a first electrode 10 and a second electrode 20. The first electrode 10 includes a first current collector 11, a reinforcing layer 12, and a first active material layer 13. The first current collector 11 includes a first main body portion 111 and a first tab 112. The first tab 112 is disposed on one side of the first main body portion 111 along the width direction Y of the first electrode 10. The first active material layer 13 is disposed on the surface of the first main body portion 111. The reinforcing layer 12 covers a portion of the first tab 112 and a portion of the first active material layer 13. The thickness D2 of the reinforcing layer 12 satisfies the following condition: D1≤D2≤D1+D3, where D1 is the thickness of the first main body portion 111 and D3 is the thickness of the first active material layer 13. The first electrode 10 and the second electrode 20 are wound together along the winding direction.

[0038] For example, the first electrode 10 can be a negative electrode, and the second electrode 20 can be a positive electrode. The first current collector 11 is a negative current collector, such as copper foil.

[0039] The first main body portion 111 is the region on the first current collector 11 that carries the active material layer, and the first tab 112 is a protrusion extending outward from the first main body portion 111 along the width direction Y, for connection with an external circuit or adapter plate. The first active material layer 13 is coated on the surface of the first main body portion 111, for example, a negative electrode active material layer containing graphite or silicon-based materials.

[0040] In embodiments where the first electrode is a negative electrode, the reinforcing layer 12 can be made of a glue layer, polyimide, or polyester coating, etc. The reinforcing layer 12 covers a portion of the first tab 112 and a portion of the first active material layer 13; that is, the reinforcing layer 12 spans the root region of the tab and covers a portion of the tab near the first main body 111 and the surface of the portion of the first active material layer 13 adjacent to the tab. The first tab 112 is a negative tab, which can also be copper foil. Since copper foil is easily bent, the reinforcing layer 12 is provided at the interface between the first tab 112 and the first active material layer 13 to provide support for the first tab 112, enhancing the structural strength at the connection between the tab and the first main body 111, and reducing the risk of the tab folding, breaking, or short-circuiting with adjacent electrodes during the winding process.

[0041] The thickness D2 of the reinforcing layer 12 is limited to be greater than or equal to the thickness D1 of the first main body portion 111 and less than or equal to the sum of the thickness D1 of the first main body portion 111 and the thickness D3 of the first active material layer 13. D2 ≥ D1 ensures that the reinforcing layer 12 has sufficient structural thickness to resist the bending stress generated when the tab is folded. If the thickness of the reinforcing layer 12 is less than D1, its bending strength is insufficient to effectively protect the root of the tab, and the tab is still prone to folding or breaking under winding tension and subsequent use. D2 ≤ D1 + D3 ensures that the upper limit of the thickness of the reinforcing layer 12 will not exceed the total thickness of the first main body portion 111 and the first active material layer 13, thus avoiding, to some extent, excessive protrusion of the reinforcing layer 12 into the external space and additional occupation of the thickness space inside the battery.

[0042] An isolation membrane 30 is disposed between the first electrode 10 and the second electrode 20 and is wound along the winding direction to form an electrode assembly 100.

[0043] The second electrode 20 includes a second current collector and a second active material layer. The second current collector includes a second main body and a second tab. The second tab is disposed on one side of the second main body along the width direction Y, and the second active material layer is disposed on the surface of the second main body.

[0044] The second electrode 20 can be a positive electrode, and the second current collector is a positive current collector, such as aluminum foil. The second main body is the area on the second current collector that carries the active material layer. The second tab is a protrusion extending outward from one side of the second main body along the width direction Y, used for electrical connection with an external circuit or adapter. The second active material layer is coated on the surface of the second main body, for example, containing positive active material layers such as lithium cobalt oxide, lithium iron phosphate, or ternary materials. The second tab is disposed on one side of the second main body along the width direction Y, and its position can be on the same side as the first tab 112 or on the opposite side, depending on the tab lead-out direction when the electrode assembly 100 is wound. After winding, the second tab and the first tab 112 are located at opposite ends or different positions on the same end of the electrode assembly 100. Since the material of the second tab is aluminum foil, its hardness is greater than that of copper foil and it is not easy to bend. Therefore, the reinforcing layer 12 can be omitted on the surface of the area where the second tab connects to the second active material layer to increase the energy density of the battery.

[0045] In the above scheme, by covering part of the first tab 112 and part of the first active material layer 13 with the reinforcement layer 12 respectively, and D1≤D2, the reinforcement layer 12 has sufficient structural strength to protect the tab from being easily folded and reduce the risk of tab breakage, falling off or overlapping; at the same time, by D2≤D1+D3, the reinforcement layer 12 will not occupy too much space inside the battery, thereby improving the reliability of the battery without affecting the battery energy density.

[0046] Figure 5This is a partial structural schematic diagram of the first electrode sheet in some embodiments of this application.

[0047] like Figure 5 As shown, in some embodiments, the reinforcing layer 12 is a porous ion-conducting layer, which includes a first region 113 located on the first tab 112 and a second region 114 located on the first active material layer 13; the average porosity P1 of the first region 113 and the average porosity P2 of the second region 114 satisfy: 5% ≤ P1 < P2 ≤ 50%, and 10% ≤ P2 - P1 ≤ 45%.

[0048] The reinforcing layer 12 is not a dense, non-porous structure, but rather a functional layer with a porous structure capable of conducting ions. The material of the porous ion-conducting layer can include a polymer matrix (such as polyimide, polyester, polyvinylidene fluoride, etc.) and ceramic particles dispersed therein (such as alumina, boehmite, silica, etc.). The porous structure is formed by controlling the amount of pore-forming agent or coating process parameters. The porous ion-conducting layer can be formed by coating, where a slurry containing a pore-forming agent is coated onto the surfaces of the first tab 112 and the first active material layer 13, and then dried and cured to form a porous structure; alternatively, it can be prepared by methods such as phase inversion, where phase separation occurs in a polymer solution in a non-solvent to form pores.

[0049] The porous ion-conducting layer includes a first region 113 on the first tab 112 and a second region 114 on the first active material layer 13. The first region 113 covers the surface of the root of the first tab 112, and the second region 114 covers the surface of the portion of the first active material layer 13 adjacent to the first tab 112. Since the first tab 112 is located below the first region 113, it does not participate in the electrochemical reaction itself. Lithium ions do not need to penetrate the reinforcing layer 12 in this region to insert or extract. Therefore, the porosity of this region can be set to be relatively low to prioritize the mechanical strength of the first region 113 and provide sufficient tensile strength and bending resistance to protect the root of the first tab 112.

[0050] Below the second region 114 lies the first active material layer 13, which is the main region for lithium-ion insertion and extraction. If the porosity of the reinforcing layer 12 in this region is too low, the migration path of lithium ions from the electrolyte to the surface of the active material will be severely hindered, causing this part of the active material to be unable to participate in the reaction normally, resulting in capacity loss. Therefore, the average porosity P2 of the second region 114 is set to be greater than the average porosity P1 of the first region 113.

[0051] Specifically, P1 ≥ 5% ensures that a continuous distribution of pore channels exists within the first region 113, allowing the electrolyte near the base of the tab to flow through these pores to a certain extent. This reduces the risk of localized electrolyte bridging due to complete densification in this region, thus affecting ion replenishment in the active material region near the tab. In other words, the presence of continuous liquid phase channels within the reinforcing layer 12 prevents complete ion blockage and avoids a sharp decline in the utilization rate of the active material below this region.

[0052] Meanwhile, with P2≤50%, the second region 114 has a high porosity to facilitate ion passage while still retaining a sufficient solid skeleton to maintain the structural integrity of the reinforcing layer 12, reducing the risk of the reinforcing layer 12 collapsing or cracking during battery cycle expansion and contraction due to excessive porosity.

[0053] Meanwhile, the setting of 10% ≤ P2 - P1 ≤ 45% provides a sufficient porosity difference, causing lithium ions in the electrolyte to preferentially transport through the second region 114, which has higher porosity and lower transport resistance, forming an effective ion transport gradient and guiding lithium ions to the surface of the first active material layer 13 below the second region 114. Specifically, the lower limit of 10% ensures a significant porosity difference between the first region 113 and the second region 114, allowing lithium ions to preferentially choose the second region 114 for transport due to the concentration-driven effect. Because the second region has lower ion transport resistance, it reduces the obstruction of the reinforcing layer 12 to ion transport in the active material region. Lithium ions will not uniformly pass through the first region 113 and the second region 114, thus guiding lithium ions to flow to the surface of the active material layer to participate in the reaction in the area covered by the reinforcing layer 12. The upper limit of 45% can, to some extent, avoid the problem of stress concentration at the interface between the first region 113 and the second region 114 due to the difference in expansion and contraction rates caused by an excessively large porosity difference, which would affect the adhesion stability of the reinforcing layer 12.

[0054] Moreover, there is a synergistic effect between the thickness condition and the porosity condition of the reinforcing layer 12. The lower limit of thickness D2 ≥ D1 ensures that the first region 113 with low porosity still has sufficient tensile strength; the upper limit of thickness D2 ≤ D1+D3 limits the longest transport path of ions in the second region 114, which to some extent prevents the thick layer from offsetting the rate advantage of high porosity.

[0055] For example, the average porosity P1 of the first region 113 and the average porosity P2 of the second region 114 can be obtained by SEM (Scanning Electron Microscope) cross-sectional image analysis, including the following steps: The cross-section of the reinforced layer 12 was observed using FIB-SEM (Focused Ion Beam Scanning Electron Microscopy). Five cross-sectional SEM images were acquired in each of the first region 113 and the second region 114. The acquired SEM images were imported into ImageJ image processing software for binarization. The corresponding regions were selected as regions of interest (ROIs). The proportion of pore pixels in the region was calculated, and the average porosity P1 of the first region 113 and the average porosity P2 of the second region 114 were calculated.

[0056] In the above scheme, by setting the reinforcing layer 12 as a porous ion-conducting layer and forming a porosity gradient between the tab side and the active material layer side, the mechanical protection strength of the reinforcing layer 12 for the tab is guaranteed to a certain extent, while the obstruction of the reinforcing layer 12 to ion transport is reduced.

[0057] In some embodiments, the reinforcing layer 12 comprises a shape memory polymer, wherein the shrinkage rate S of the shape memory polymer at a temperature of 40°C to 75°C satisfies 3% ≤ S ≤ 12%.

[0058] Shape memory polymers are a class of smart materials that can recover their original shape from a temporarily deformed state under the action of external stimuli (such as temperature changes). In the embodiments of this application, the shape memory polymer contained in the reinforcing layer 12 can shrink when heated during battery manufacturing or use, thereby exerting a pressing effect on the root of the first tab 112 and the edge of the first active material layer 13.

[0059] The temperature range of 40℃ to 75℃ covers the temperature range of the battery during hot pressing, formation, aging, and normal charge and discharge use.

[0060] For example, the shape memory polymer can be polyurethane, and the reinforcing layer can be prepared by extrusion coating. For example, polyurethane can be dissolved with N-methylpyrrolidone or ethyl acetate to form a slurry, and an ultra-thin coating of 3~10 μm can be obtained by coating, with an activation temperature greater than or equal to 45°C.

[0061] Shape memory polymers can also be acrylates, and the reinforcing layer can also be prepared by extrusion coating, with an activation temperature of 40℃~75℃.

[0062] When the shrinkage rate is less than 3%, the shrinkage stress generated by the reinforcing layer 12 is too small to form an effective clamping force at the contact interface, and there is still a risk of peeling at the interface, so the protective effect of the reinforcing layer 12 cannot be fully realized.

[0063] When the shrinkage rate is greater than 12%, the stress generated by the shrinkage of the reinforcing layer 12 is too large. On the one hand, it may exceed the interfacial bonding strength between the reinforcing layer 12 and the first current collector 11, causing the reinforcing layer 12 to detach from the surface of the first current collector 11 or delaminate. On the other hand, the excessive shrinkage stress will generate additional compressive load in the edge region of the first active material layer 13, causing the active material layer in this region to be over-compacted, resulting in a decrease in local porosity and insufficient electrolyte wetting. Lithium ions will have difficulty inserting and extracting smoothly during charging and discharging, thereby causing local overcharging or lithium plating.

[0064] For example, the shrinkage rate of the reinforcing layer 12 can be obtained by the following test method: measure the original length L0 (mm) of the reinforcing layer before heating, and then measure the length L1 (mm) of the reinforcing layer after cooling. Then the shrinkage rate S of the reinforcing layer 12 is S = (L0-L1) / (L0)*100%. If the shrinkage rate S is positive, it indicates that the reinforcing layer has shrunk; if the shrinkage rate S is negative, it indicates that the reinforcing layer has expanded due to heat.

[0065] In the above scheme, by limiting the shrinkage rate within a suitable range, the reinforcing layer 12 can generate sufficient shrinkage stress to resist peeling, and to a certain extent prevents the shrinkage stress from exceeding the bonding strength between the reinforcing layer 12 and the current collector interface, or from excessively compressing the edge of the first active material layer 13 to cause local overcharging or lithium plating.

[0066] Furthermore, the thickness D2' of the shrinkage reinforcement layer 12 satisfies D1 ≤ D2' ≤ 1.2×(D1+D3).

[0067] Even after shrinkage, the thickness of the reinforcing layer 12 is still not less than the thickness D1 of the first main body 111, thereby maintaining the reinforcing effect of the reinforcing layer 12 on the root of the first electrode 112 and continuing to provide sufficient bending protection for the first electrode 112. On the other hand, the upper limit of the shrinkage thickness is set to 1.2×(D1+D3), which provides sufficient safety margin for the thickness expansion that may occur during the shrinkage process due to the law of volume conservation, and reduces the risk of puncturing the isolation membrane 30 due to excessive expansion.

[0068] Figure 6 This is a cross-sectional schematic diagram of the first electrode sheet in some embodiments of this application.

[0069] In some embodiments, the width by which one edge of the first electrode 10 protrudes relative to the same edge of the second electrode 20 along the width direction Y is L. For example... Figure 6As shown, the reinforcing layer 12 has multiple micro-protrusions 115 on its surface away from the first current collector 11. The micro-protrusions 115 extend along the length direction X of the first electrode 10. The height h of the micro-protrusions 115 satisfies: 1μm≤h≤min(D2-D1,0.5L), and h≥0.1×(D2-D1).

[0070] For example, the first electrode 10 can be a negative electrode, and the second electrode 20 can be a positive electrode. In the electrode assembly 100, the width of the negative electrode is typically greater than the width of the positive electrode, that is, the edge of the negative electrode along the width direction Y protrudes outward relative to the edge of the positive electrode on the same side, with a protrusion width of L. The purpose is to ensure that the negative electrode can completely cover the positive electrode and prevent lithium deposition at the edge of the positive electrode. Optionally, the value of L ranges from 0.5 mm to 3 mm.

[0071] The reinforcing layer 12 has multiple micro-protrusions 115 on its surface away from the first current collector 11. The micro-protrusions 115 extend along the length direction X of the first electrode 10. This extension direction allows the micro-protrusions 115 to form continuous linear contact with the surface of the separator 30 during the winding process, rather than point contact, which is beneficial for uniform stress distribution.

[0072] If the height of the micro-protrusion 115 is less than 1 μm, the protrusion is too short and it is difficult to form an effective mechanical interlock with the separator 30 or adjacent layers. When the first electrode 10 is bent or vibrated, the reinforcing layer 12 is still prone to slippage and peeling.

[0073] If h ≤ D2 - D1, the root of the micro-protrusion 115 is completely supported by the body material of the reinforcing layer 12, meaning the height of the protrusion does not exceed the thickness of the reinforcing layer 12 itself. This avoids, to some extent, the additional peeling torque at the interface between the micro-protrusion 115 and the first current collector 11 caused by excessive protrusion, preventing the micro-protrusion 115 from tearing directly from the current collector interface under stress. If h ≤ 0.5L, since the width of the protrusion of the first electrode 10 relative to the edge of the second electrode 20 on the same side is L, there is no positive electrode active material layer in this protrusion area, which is a safe blank area. Limiting the height of the micro-protrusion 115 to within 0.5L ensures that the micro-protrusion 115 will not penetrate the separator 30 and contact the positive electrode active material or the positive electrode current collector when deformed under pressure or when the separator 30 is deformed, thereby reducing the risk of short circuit caused by puncturing the separator 30 due to excessive protrusion height.

[0074] Meanwhile, the setting of h≥0.1×(D2-D1) makes the height of the micro-protrusion 115 proportional to the thickness of the reinforcing layer 12. When the reinforcing layer 12 is thicker, D2-D1 is larger, and the height of the protrusion also increases accordingly. To a certain extent, this avoids the situation where the reinforcing layer 12 is very thick but the protrusion is very short, and prevents the interlocking effect with the adjacent layer from being lost due to the relatively short protrusion, thus forming a proportional coordination between structure and size.

[0075] Figure 7 This is a partial structural schematic diagram of the first electrode sheet in some other embodiments of this application.

[0076] like Figure 7 As shown, in some embodiments, the micro-protrusions 115 are strip-shaped protrusions formed on the surface of the reinforcing layer 12 facing away from the first current collector 11. The micro-protrusions 115 extend along the length direction X of the first electrode 10 and are distributed at intervals along the width direction Y of the first electrode 10. Multiple micro-protrusions 115 are arranged parallel to each other, and the spacing D4 between adjacent micro-protrusions 115 is substantially equal. "Substantially equal" means that the ratio of the difference in spacing between adjacent micro-protrusions 115 to the spacing between adjacent micro-protrusions 115 is less than or equal to 0.05. For example, if the spacing between two adjacent micro-protrusions 115 is A, and the spacing between another two adjacent micro-protrusions 115 is B, then |AB| / A is less than or equal to 0.05, meaning that the absolute value of the difference between A and B divided by A is less than or equal to 0.05.

[0077] Figure 8 This is a cross-sectional schematic diagram of the reinforcing layer and micro-protrusions in some embodiments of this application.

[0078] like Figure 8 As shown, in a cross-section perpendicular to the length direction X, the cross-section of the micro-protrusion 115 can be an isosceles trapezoid with a rounded top transition. The micro-protrusion 115 includes a root 1151 connected to the reinforcing layer 12, a top 1152 located on the side away from the first current collector 11, and two sidewalls 1153 connecting the root and the top. The two connection positions of the root 1151 are respectively provided with rounded corners to reduce stress concentration at the connection between the micro-protrusion 115 and the reinforcing layer 12.

[0079] In some embodiments, the micro-protrusion 115 may also be a semi-circular, elliptical arc, or trapezoidal structure with a rounded top.

[0080] In some embodiments, the root 1151 of the micro-protrusion 115 is rounded, and the radius of the rounded corner is r. The radius r is measured along a cross section perpendicular to the length direction X, satisfying the following: 0.2h≤r≤0.5h.

[0081] By providing a rounded corner at the root 1151 of the micro-protrusion 115, the local stress generated at the root when the micro-protrusion 115 is squeezed by the isolation membrane 30 can be reduced, thereby reducing the risk of the micro-protrusion 115 peeling off or tearing from the surface of the reinforcing layer 12.

[0082] In some embodiments, the number of micro-protrusions 115 is q, where q is a positive integer greater than or equal to 2, preferably 2 to 20. The plurality of micro-protrusions 115 are uniformly distributed along the width direction Y, and the center lines of the micro-protrusions 115 are parallel to each other and extend along the length direction X.

[0083] Multiple micro-protrusions 115 are preferably disposed in the middle region of the reinforcing layer 12 along the width direction Y, so that an edge gap is maintained between the outermost micro-protrusion 115 and the side edge of the reinforcing layer 12, avoiding the micro-protrusion 115 from directly forming a suspended end. The micro-protrusion 115 extends continuously along the length direction X, and the two ends of the micro-protrusion 115 do not exceed the boundary of the reinforcing layer 12 along the length direction X.

[0084] In the embodiment where the first electrode 10 is a negative electrode and the second electrode 20 is a positive electrode, the micro-protrusion 115 is preferably located in the blank area where the first electrode 10 protrudes relative to the second electrode 20, and the distribution range of the micro-protrusion 115 along the width direction Y does not exceed the blank area.

[0085] In some embodiments, the micro-protrusions 115 are integrally formed from the same material as the reinforcing layer 12. The micro-protrusions 115 can be formed by microstructure embossing, microgravure coating, screen coating, or die forming. After the micro-protrusions 115 are formed, they are dried or cured to form a continuous connection between the micro-protrusions 115 and the reinforcing layer 12, rather than being formed by the attachment of individual particles.

[0086] The height h of the micro-protrusion 115 is measured using the following method: An adjacent surface region without micro-protrusions 115 is selected on the reinforcing layer 12, and a reference surface of the reinforcing layer 12 is obtained by fitting this region. The maximum distance from the reference surface along the thickness direction of the reinforcing layer 12 to the highest point of the micro-protrusion 115 is taken as the height of the corresponding micro-protrusion 115. For multiple micro-protrusions 115, the maximum value among all measured heights of the micro-protrusions 115 is taken as the height h of the micro-protrusion 115. The fillet radius r of the micro-protrusion 115 is measured in the same cross-section.

[0087] Specifically, at least five cross-sections can be selected along the length direction X at both ends and the middle of the micro-protrusion 115. The cross-sectional profiles can be obtained using an optical profilometer, laser confocal microscope, or scanning electron microscope. The height, width, spacing, and root fillet radius of the micro-protrusion 115 can then be calculated based on the cross-sectional profiles. During measurement, the sample should be in a dry, cured, and unpressurized state, and the ends of the micro-protrusion 115, the edges of the reinforcing layer 12, and areas with obvious defects should be avoided.

[0088] In the above solution, by limiting the micro-protrusions 115 to a suitable range, the risk of peeling off the reinforcing layer 12 can be reduced, and short circuits can be avoided to a certain extent.

[0089] Figure 9 This is a partial structural schematic diagram of the first electrode sheet in some other embodiments of this application.

[0090] like Figure 9As shown, in some embodiments, the reinforcing layer 12 includes a first side 121 and a second side 122 disposed opposite to each other along the length direction X of the first electrode 10; the first electrode tab 112 includes a first side edge 116 and a second side edge 117 disposed opposite to each other along the length direction X, the first side edge 121 being aligned with the first side edge 116, and the second side edge 122 being aligned with the second side edge 117.

[0091] For example, the length direction X of the first electrode 10 is the longitudinal direction after the electrode is unfolded, that is, the winding direction. The reinforcing layer 12 covers a portion of the first tab 112 and a portion of the first active material layer 13, and its boundary along the length direction X is defined by a first side 121 and a second side 122. The first tab 112, as a protrusion extending outward from the first body portion 111, also has a first side edge 116 and a second side edge 117 along the length direction X. The first side edge 121 of the reinforcing layer 12 is aligned with the first side edge 116 of the tab, and the second side edge 122 is aligned with the second side edge 117 of the tab, that is, the coverage area of ​​the reinforcing layer 12 in the length direction X is completely consistent with the width of the tab in the length direction X.

[0092] In the above solution, by aligning the two sides of the reinforcing layer 12 in the length direction X with the two sides of the first electrode tab 112 in the length direction X, the reinforcing layer 12 can completely cover the root area of ​​the first electrode tab 112, reducing the risk of the edge of the first electrode tab 112 folding or cracking during winding due to not being covered by the reinforcing layer 12. At the same time, it also prevents the reinforcing layer 12 from extending excessively beyond the edge of the first electrode tab 112, reducing the risk of the suspended end lifting or peeling off during winding or cycling, and further improving the adhesion reliability of the reinforcing layer 12 and the protection effect on the first electrode tab 112.

[0093] In some embodiments, in the direction from the first tab 112 to the first main body portion 111, the widths of the first tab 112 and the reinforcing layer 12 gradually increase along the length direction X.

[0094] For example, the direction in which the first tab 112 points towards the first main body portion 111 is the direction from the free end of the first tab 112 towards the root of the first tab 112. Along this direction, the width of the first tab 112 gradually increases along its length direction X, that is, the width of the first tab 112 is larger in the region near the root and gradually narrows as it extends towards the free end. The width of the reinforcing layer 12 is also correspondingly larger in the region near the root and gradually narrows towards the free end of the first tab 112.

[0095] In the above solution, by setting the width of the first electrode tab 112 and the reinforcing layer 12 to gradually change, not only can the connection stability between the first electrode tab 112 and the first main body 111 be increased, but the risk of electrode tab flipping can also be further reduced.

[0096] In some embodiments, the electrode assembly 100 includes an inner ring region 41 and an outer ring region 42. The first electrode 10 is wound with a total number of turns N along the winding direction. From the inside to the outside of the winding direction, the first turn to the k1th turn of the first electrode 10 is the inner ring region 41, and the k2th turn to the Nth turn of the first electrode 10 is the outer ring region 42. Here, k1 is 30% of the total number of turns N, k2 is 70% of the total number of turns N, and N, k1, and k2 are all positive integers. There are multiple first electrode tabs 112, some of which are located in the inner ring region 41 and some of which are located in the outer ring region 42. A reinforcing layer 12 is provided on one side of at least some of the first electrode tabs 112 located in the inner ring region 41. A reinforcing layer 12 is provided on one side of each of the multiple first electrode tabs 112. The thickness of the multiple reinforcing layers 12 gradually decreases in the direction from the inner ring region 41 to the outer ring region 42.

[0097] For example, after winding, the electrode assembly 100 is arranged radially outward from the winding center (i.e., the core) as the 1st, 2nd, ..., Nth turns, where the 1st turn is the innermost turn and the Nth turn is the outermost turn. The inner turn region 41 is defined as turns 1 to k1, and the outer turn region 42 is defined as turns k2 to N, where k1 is 30% of the total number of turns N and k2 is 70% of the total number of turns N. When k1 is calculated as a decimal, it is rounded to the nearest integer. For example, when the total number of turns N is 8, the inner turn region 41 is turns 1 to 2, and the outer turn region 42 is turns 6 to 8. When the total number of turns N is 10, the inner turn region 41 is turns 1 to 3, and the outer turn region 42 is turns 7 to 10. When the total number of laps N is 15, the inner zone 41 consists of laps 1 to 5, and the outer zone 42 consists of laps 11 to 15. When the total number of laps N is 20, the inner zone 41 consists of laps 1 to 6, and the outer zone 42 consists of laps 14 to 20.

[0098] The winding direction of the first tab 112 is the same as the direction of travel when the electrode sheet is wound. There are multiple first tabs 112, spaced apart along the winding direction and distributed at different radial positions on the electrode assembly 100. The first tab 112 located in the inner ring region 41 has the smallest radius of curvature at its winding position, and experiences the greatest bending stress on the first electrode sheet 10 during bending. The root of the first tab 112 also experiences the most intense tensile and shear stress during the bending process of the first electrode sheet 10, thus posing the highest risk of buckling. A reinforcing layer 12 is provided on one side of these first tabs 112 to effectively strengthen the connection between the root of the first tab 112 and the main body of the first electrode sheet 10, resisting bending stress and reducing the risk of buckling or breaking of the first tab 112 during winding.

[0099] Meanwhile, in the direction from the inner ring region 41 to the outer ring region 42 (i.e., radially outward from the core), the thickness of the multiple reinforcing layers 12 gradually decreases. This is because the radius of curvature of the first electrode 10 is larger the closer to the outer ring, the bending stress gradually decreases, and the risk of the first electrode tab 112 flipping is also reduced. Therefore, the need for reinforcement of the outer ring first electrode tab 112 is relatively low. By setting a thicker reinforcing layer 12 in the inner ring to cope with the maximum bending stress, and setting a thinner reinforcing layer 12 in the outer ring to save space while ensuring basic protection, a differentiated distribution of the thickness of the reinforcing layer 12 is achieved. In addition, the space in the inner ring region 41 is more confined, and the electrolyte wetting is relatively more difficult. Appropriately controlling the thickness of the inner ring reinforcing layer 12 also helps to avoid excessive occupation of the gap between the inner ring electrodes, and to a certain extent prevents the electrolyte storage space from being squeezed due to excessive thickness of the reinforcing layer 12.

[0100] In the above scheme, by setting a reinforcing layer 12 in the inner ring region 41 where the bending stress is the greatest, the first tab 112, which is most prone to flipping, can be prevented from flipping to a certain extent. Moreover, the reinforcing layer 12 decreases as the number of rings increases, which can reduce the risk of the first tab 112 flipping and further save the internal space of the battery, thereby improving the energy density of the battery.

[0101] In some embodiments, the number of first tabs 112 is m, and a reinforcing layer 12 is provided on one side of each of the n first tabs 112; wherein, 1≤n≤m / 3, and m and n are both positive integers.

[0102] For example, the first electrode 10 has m first tabs 112 along the winding direction, where m is the total number of first tabs 112 along the winding direction. The specific value of m is determined according to the battery capacity and design requirements; for example, m can be 4, 6, 9, or 12. The multiple first tabs 112 are spaced apart along the winding direction and are located at different radial positions after the electrode assembly 100 is wound, for example, some are located in the inner ring region 41 and some in the outer ring region 42. A reinforcing layer 12 is provided on n of the first tabs 112, where n does not exceed one-third of m. n is the number of first tabs 112 with the reinforcing layer 12. n represents the number of tabs actually coated or attached with the reinforcing layer 12 among the m first tabs 112.

[0103] Since the risk of buckling of the first electrode tab 112 is not evenly distributed across all first electrode tabs 112, the first electrode tabs 112 in the inner ring region 41 are most prone to buckling due to their small radius of curvature and high bending stress, while the first electrode tabs 112 in the outer ring region 42 have a lower risk of buckling due to their large radius of curvature and relatively mild bending stress. Therefore, it is not necessary to provide a reinforcing layer 12 on all first electrode tabs 112; only the first electrode tabs 112 with the highest risk of buckling should be selected.

[0104] The risk of the first tab 112 folding is mainly concentrated in the inner ring region 41, which accounts for approximately 30% of the total number of winding turns. Correspondingly, the number of tabs located in the inner ring region 41 accounts for approximately 30% of the total number of tabs m, i.e., approximately m / 3. Therefore, the specific value of n can be determined sequentially from the inside out based on the degree of danger of the ring where the first tab 112 is located: starting from the first turn (the innermost turn), the first tabs 112 are selected radially outward turn by turn to install the reinforcement layer 12. If the number of first tabs 112 in the inner ring region 41 is ≤ m / 3, then the reinforcement layer 12 is installed on all the first tabs 112 located in the inner ring region 41; if the number of first tabs 112 in the inner ring region 41 is > m / 3, then starting from the first turn, the m / 3 first tabs 112 closest to the center of the core are selected sequentially from the inside out to install the reinforcement layer 12.

[0105] For example, when m=4, m / 3≈1.33, rounded down to 1, n=1, meaning that starting from the first ring, the first tab 112 closest to the center of the core is selected for reinforcement layer 12. When m=6, m / 3=2, n=2, meaning that starting from the first ring, two first tabs 112 located in the inner ring region 41 are selected for reinforcement layer 12. When m=9, m / 3=3, n=3, meaning that starting from the first ring, three first tabs 112 located in the innermost ring region 41 are selected for reinforcement layer 12. When m=12, m / 3=4, then reinforcement layer 12 is applied to the four inner ring tabs starting from the first ring.

[0106] If n exceeds m / 3, that is, if more than one-third of the first electrode tabs 112 are provided with reinforcing layers 12, on the one hand, it will increase the material cost and the time for coating or adhesive application, reducing the manufacturing efficiency; on the other hand, too many reinforcing layers 12 will increase the overall rigidity of the first electrode 10, which may affect the flexibility of winding, or form too many protruding areas on the surface of the first electrode 10, squeezing the separator 30 and electrolyte storage space, which is not conducive to battery performance.

[0107] In the above scheme, by controlling n to within m / 3, it is possible to perform targeted reinforcement on the first tab 112, which has the highest risk of folding, effectively reducing the probability of tab folding, breakage, or short circuit. It can also avoid the problem of reduced preparation efficiency and space occupation caused by too many reinforcement layers 12 to a certain extent.

[0108] In some embodiments, the width of one side edge of the first electrode 10 protruding relative to the same side edge of the second electrode 20 along the width direction Y is L; the width of the overlapping portion of the reinforcing layer 12 and the first main body 111 along the width direction Y is less than or equal to L.

[0109] For example, the first electrode 10 can be a negative electrode and the second electrode 20 can be a positive electrode. In battery design, in order to ensure that the negative electrode can completely cover the positive electrode and prevent lithium plating from occurring at the edge of the positive electrode due to the inability to properly insert lithium ions, the width of the negative electrode is usually greater than the width of the positive electrode. That is, at least one edge of the negative electrode along the width direction Y protrudes outward relative to the same edge of the positive electrode, and the protrusion width is L.

[0110] The reinforcing layer 12 covers a portion of the first active material layer 13, meaning that the reinforcing layer 12 extends from the region of the first tab 112 toward the first main body 111, overlapping with the first active material layer 13 on the first main body 111. The width of this overlapping portion along the width direction Y is limited to less than or equal to L. Since the width L of the first electrode 10 protruding relative to the second electrode 20 is a safe blank area, limiting the overlap width between the reinforcing layer 12 and the first main body 111 to within L means that the reinforcing layer 12 does not exceed the protruding boundary of the first electrode 10 relative to the second electrode 20 in the width direction Y.

[0111] In the above scheme, by setting the width of the overlapping portion of the reinforcing layer 12 and the first main body 111 along the width direction Y to be less than or equal to the width of the first electrode 10 exceeding the second electrode 20, the first active material layer 13 of the first electrode 10 can exceed the second active material layer of the second electrode 20 in the width direction Y, thereby reducing the lithium plating phenomenon.

[0112] In some embodiments, the width H2 of the reinforcing layer 12 along the width direction Y satisfies: 2 / 5H1≤H2≤3 / 5H1; where H1 is the width of the first tab 112 along the width direction Y.

[0113] H2≥2 / 5H1 ensures that the reinforcing layer 12 has sufficient coverage area in the width direction Y of the first tab 112, which can effectively wrap and support the root area of ​​the first tab 112, dispersing the bending stress generated when the tab is folded to a wider area, and to a certain extent avoiding stress concentration in a local area of ​​the tab width, which could lead to cracking at the root of the tab, thereby reducing the risk of tab folding or breaking.

[0114] H2≤3 / 5H1 ensures that the reinforcing layer 12 does not extend excessively to the free end direction of the electrode, thus avoiding, to some extent, the reinforcing layer 12 covering the electrode welding area and affecting the welding reliability between the electrode and the adapter or busbar.

[0115] In the above solution, by limiting the ratio of the width of the reinforcing layer 12 to the width of the first electrode tab 112 to a suitable range, the risk of the first electrode tab 112 folding over can be reduced without affecting the welding of the electrode tab.

[0116] In some embodiments, the surface of the first tab 112 has a solder mark 118, and the solder mark 118 and the reinforcing layer 12 are spaced apart along the width direction Y; the distance H3 between the side of the solder mark 118 facing the first main body 111 and the first main body 111 satisfies: H3≥1 / 2H1; where H1 is the width of the first tab 112 along the width direction Y.

[0117] Solder mark 118 is a connection mark formed during the welding of the electrode tab, which is usually used to connect the electrode tab to the adapter or busbar.

[0118] The weld stamp 118 and the reinforcing layer 12 are spaced apart along the width direction Y, that is, they are kept at a certain distance. This avoids the high temperature and pressure during welding from directly acting on the reinforcing layer 12, and prevents the reinforcing layer 12 from failing due to melting due to heat or deformation due to pressure.

[0119] Meanwhile, the distance H3 from the solder mark 118 to the root of the first tab 112 is not less than half the tab width H1, so that the solder mark 118 is located in the outer region of the width of the first tab 112, away from the stress concentration area at the root of the first tab 112. In this way, when multiple layers of first tabs 112 are stacked and welded, the bonding of each layer of first tabs 112 in the area of ​​the solder mark 118 is more uniform, and the impact of welding vibration on the root of the first tab 112 is smaller, thereby reducing the risk of tearing at the root of the first tab 112. If the solder mark 118 is too close to the root of the first tab 112, the pressure and vibration applied during welding will generate large shear stress at the root of the first tab 112, which can easily lead to cracks or tears at the interface between the first tab 112 and the first active material layer 13.

[0120] In the above scheme, the solder stamp 118 and the reinforcing layer 12 are spaced apart along the width direction Y, so that the welding of the first electrode tab 112 will not affect or damage the reinforcing layer 12, thus ensuring the integrity of the reinforcing layer 12 to a certain extent. By limiting the ratio of H3 to H1 to a suitable range, it is easy to weld between multiple layers of first electrode tabs 112, and it is not easy to cause the first electrode tab 112 to tear.

[0121] In some embodiments, the first tab 112 is provided with a reinforcing layer 12 on both sides of the first electrode 10 along the thickness direction.

[0122] The first electrode 10 has two surfaces in the thickness direction, and the first tab 112, as part of the first current collector 11, also has two opposing surfaces. Reinforcing layers 12 are provided on both the upper and lower sides of the first tab 112, meaning that both the front and back sides of the tab are covered by reinforcing layers 12. This double-sided coverage, compared to providing reinforcing layers 12 on only one side, provides more uniform support when the first tab 112 is subjected to bending forces, avoiding asymmetrical stress caused by unilateral reinforcement, and making the stress distribution on both sides of the first tab 112 more balanced during winding and bending. Simultaneously, the double-sided reinforcing layers 12 further increase the interfacial contact area between the reinforcing layers 12 and the first tab 112. Even if the adhesion decreases on one side due to thermal aging or electrolyte wetting, the reinforcing layer 12 on the other side can still maintain its fixing and protective function for the first tab 112, thereby effectively reducing the risk of tab flipping and further improving battery reliability.

[0123] Secondly, embodiments of this application also provide a battery including the electrode assembly 100 of any of the above embodiments.

[0124] Thirdly, embodiments of this application also provide an electrical device, including the aforementioned battery.

[0125] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An electrode assembly, characterized in that, include: Separating membrane; The first electrode includes a first current collector, a reinforcing layer, and a first active material layer. The first current collector includes a first main body and a first tab. The first tab is disposed on one side of the first main body along the width direction of the first electrode. The first active material layer is disposed on the surface of the first main body. The reinforcing layer covers a portion of the first tab and a portion of the first active material layer. The thickness D2 of the reinforcing layer satisfies the following condition: D1≤D2≤D1+D3, where D1 is the thickness of the first main body and D3 is the thickness of the first active material layer. The second electrode is formed by winding the first electrode, the separator, and the second electrode together along the winding direction.

2. The electrode assembly according to claim 1, characterized in that, The reinforcing layer is a porous ion-conducting layer, comprising a first region located on the first tab and a second region located on the first active material layer; the average porosity P1 of the first region and the average porosity P2 of the second region satisfy the following: 5% ≤ P1 < P2 ≤ 50%, and 10% ≤ P2 - P1 ≤ 45%.

3. The electrode assembly according to any one of claims 1 or 2, characterized in that, The reinforcing layer comprises a shape memory polymer, and the shrinkage rate S of the shape memory polymer at a temperature of 40℃~75℃ satisfies: 3%≤S≤12%.

4. The electrode assembly according to any one of claims 1-3, characterized in that, The width by which one edge of the first electrode protrudes relative to the same edge of the second electrode along the width direction is L; The reinforcing layer has multiple micro-protrusions on its surface opposite to the first current collector, and the micro-protrusions extend along the length direction of the first electrode; the height h of the micro-protrusions satisfies: 1μm ≤ h ≤ min( D2 - D1 , 0.5L ), and h ≥ 0.1×(D2 - D1).

5. The electrode assembly according to any one of claims 1-4, characterized in that, In the direction from the first electrode tab to the first main body, the widths of the first electrode tab and the reinforcing layer gradually increase along the length of the first electrode sheet.

6. The electrode assembly according to any one of claims 1-5, characterized in that, The electrode assembly includes an inner ring region and an outer ring region. The first electrode sheet is wound with a total number of turns N along the winding direction. From the inside to the outside of the winding direction, the first turn to the k1th turn of the first electrode sheet is the inner ring region, and the k2th turn to the Nth turn of the first electrode sheet is the outer ring region. Here, k1 is 30% of the total number of turns N, k2 is 70% of the total number of turns N, and N, k1, and k2 are all positive integers. The number of first electrodes is multiple, with some first electrodes located in the inner ring region and some first electrodes located in the outer ring region; the reinforcing layer is provided on one side of at least some of the first electrodes located in the inner ring region; The reinforcement layer is provided on one side of each of the multiple first tabs, and the thickness of the multiple reinforcement layers gradually decreases in the direction from the inner ring region to the outer ring region.

7. The electrode assembly according to any one of claims 1-6, characterized in that, The number of first electrodes is m, and the reinforcement layer is provided on one side of each of the n first electrodes; wherein, 1≤n≤m / 3, and m and n are both positive integers.

8. The electrode assembly according to any one of claims 1-7, characterized in that, The width by which one edge of the first electrode protrudes relative to the same edge of the second electrode along the width direction is L; The width of the overlapping portion of the reinforcing layer and the first main body is less than or equal to L along the width direction.

9. The electrode assembly according to any one of claims 1-8, characterized in that, The width H2 of the reinforcing layer along the width direction satisfies: 2 / 5H1≤H2≤3 / 5H1; where H1 is the width of the first electrode tab along the width direction.

10. The electrode assembly according to any one of claims 1-9, characterized in that, The surface of the first electrode tab has solder marks, and the solder marks and the reinforcing layer are spaced apart along the width direction; The distance H3 between the side of the solder mark facing the first main body and the first main body satisfies: H3≥1 / 2H1; where H1 is the width of the first electrode tab along the width direction.

11. A battery, characterized in that, Includes the electrode assembly according to any one of claims 1-10.

12. An electrical appliance, characterized in that, Includes the battery according to claim 11.

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