Pole piece, battery and electronic device

Abstract

The invention provides a pole piece, a battery and an electronic device, the pole piece comprises: a current collector, the current collector comprises a coated area and an uncoated area, the coated area comprises an active material layer, a first insulation part and a second insulation part which are arranged along a preset direction on at least one surface of the current collector in the thickness direction and are sequentially and adjacently arranged; in the thickness direction of the current collector, the thickness of the first insulating part is greater than that of the second insulating part, and the first insulating part comprises a first insulating layer and a second insulating layer coated on the first insulating layer; in the preset direction, the width of the uncoated area is W1mm, the width of the first insulating part is W2mm, and W1 / W2 is larger than or equal to 1.5 and smaller than or equal to 10. According to the pole piece, the battery and the electronic device provided by the invention, on the premise of reducing wrinkles and folding of the uncoated area, the uncoated area has enough width to be assembled with other structures in the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of secondary batteries, and in particular to a pole piece, a battery and an electronic device. Background Art

[0002] Lithium-ion batteries are widely used in new energy vehicles, consumer electronics, energy storage systems, and other fields due to their high energy density, rechargeability, safety, and environmental friendliness. The pole piece is a crucial component of lithium-ion batteries, and its stability is directly related to the battery's safety and cycle life. The pole piece typically consists of an active material layer, an insulating layer, and an uncoated area. The insulating layer lies between the active material layer and the uncoated area. However, the uncoated area is prone to flanging and wrinkling, which can lead to poor welds when the uncoated area is welded to other battery components. Summary of the Invention

[0003] The present invention proposes a pole piece, a battery and an electronic device. By providing a first insulating part and a second insulating part with a thickness difference, the first insulating part between the active material layer and the second insulating part supports the uncoated area. The first insulating part and the second insulating part cooperate to reduce wrinkles at the junction of the uncoated area and the second insulating part or reduce the folding of the uncoated area. At the same time, it is also necessary to consider that the uncoated area has sufficient width to be assembled with other structures in the battery to ensure the transmission of current.

[0004] To solve the above technical problems, the present invention is achieved through the following technical solutions.

[0005] The present invention also provides a pole piece, comprising at least:

[0006] a current collector, the current collector comprising a coated area and an uncoated area, the coated area comprising an active material layer, a first insulating portion, and a second insulating portion disposed adjacent to each other in sequence along a preset direction and on at least one side in a thickness direction of the current collector;

[0007] In the thickness direction of the current collector, the thickness of the first insulating portion is greater than the thickness of the second insulating portion, and the first insulating portion includes a first insulating layer and a second insulating layer coated on the first insulating layer;

[0008] Along the preset direction, the width of the uncoated area is W1 mm, and the width of the first insulating portion is W2 mm, satisfying 1.5≤W1 / W2≤10.

[0009] In one embodiment of the present invention, the pole piece also includes a pole ear, which protrudes from the current collector body along the preset direction. The current collector body includes the active material layer covering area and a transition zone located between the active material layer and the pole ear. The transition zone extends from one end of the current collector to the other end perpendicular to the preset direction. The second insulating portion and part of the first insulating portion are located on the surface of the pole ear, and another part of the first insulating portion is located in the transition zone.

[0010] In one embodiment of the present invention, along the preset direction, the width of the second insulating portion is W3 mm, satisfying 1.6≤W1 / W3≤25; or

[0011] The value range of W1 is 9mm-36mm.

[0012] In one embodiment of the present invention, the electrode further comprises a primer layer disposed between the active material layer and the current collector;

[0013] Along the preset direction, one end of the primer layer extends beyond the active material layer, and the width of the end of the primer layer extending beyond the active material layer is 0.1 mm to 2 mm.

[0014] In one embodiment of the present invention, the active material layer includes an active material, and the active material includes a lithium-containing phosphate material; the first insulating portion and the second insulating portion are made of an inorganic insulating material and a binder.

[0015] In one embodiment of the present invention, along the preset direction, the first insulating layer and the primer layer are spaced apart from each other;

[0016] The second insulating portion and the first insulating layer are obtained by coating the same slurry at one time.

[0017] The present invention also provides a battery, comprising at least:

[0018] A shell having an upper opening;

[0019] an electrode assembly disposed within the housing; and

[0020] A cover plate assembly with a sealed upper opening, the cover plate assembly comprising a transition piece, wherein the width direction of the transition piece comprises a first tab welding portion and a second tab welding portion symmetrically arranged along the length direction of the transition piece;

[0021] The electrode assembly is formed by stacking a positive electrode sheet, a separator, and a negative electrode sheet and then winding or laminating them, wherein the positive electrode sheet is the electrode sheet described in the above one; along a preset direction, the electrode assembly includes a body and a tab, wherein the tab includes an uncoated area and a second insulating portion and a portion of the first insulating portion provided on the same side of the tab in the thickness direction;

[0022] There are two groups of electrode assemblies. The tabs of one group of electrode assemblies and the tabs of the other group of electrode assemblies are bent relative to each other and then welded to the first tab welding portion and the second tab welding portion of the adapter sheet respectively.

[0023] In one embodiment of the present invention, the thickness of the first insulating portion is 10 μm-100 μm, or the thickness of the second insulating portion is 0.5 μm-9 μm.

[0024] In one embodiment of the present invention, the electrode assembly includes a first tape, which is arranged on the side of the tab facing away from the cover plate assembly. The first tape includes a first adhesive area, a second adhesive area, and a non-adhesive area between the first adhesive area and the second adhesive area. The first adhesive area covers the main body, and the second adhesive area covers the uncoated area. In the thickness direction of the electrode assembly, the orthographic projections of the first insulating portion and the second insulating portion are completely located within the non-adhesive area.

[0025] The present invention also provides an electronic device comprising the battery described above.

[0026] In summary, the electrode, battery and electronic device provided by the present invention, by arranging a first insulating part and a second insulating part with a thickness difference between the active material layer and the uncoated area, the first insulating part between the active material layer and the second insulating part can support the uncoated area. When there is a thickness difference between the first insulating part and the second insulating part, when the electrode is used to assemble bare batteries to perform welding after the multiple uncoated areas are converged, the thickness gradient transition from the first insulating part to the second insulating part can disperse the stress of the outer uncoated area during convergence, reduce the wrinkles at the junction of the uncoated area and the second insulating part, or reduce the folding of the uncoated area; by controlling the width ratio of the uncoated area and the first insulating part, on the premise of effectively supporting the uncoated area and reducing the wrinkles and folding of the uncoated area, it can avoid the waste of excessive space in the uncoated area, and it can also avoid the limited welding area caused by the uncoated area being welded with other structures in the battery due to the uncoated area being too small, thereby ensuring the area of ​​the welding area to ensure the transmission of current. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 Schematic diagram of a pole piece in one embodiment.

[0029] Figure 2 In one embodiment, the middle Figure 1 Cross-sectional view of the pole piece in the AA direction.

[0030] Figure 3 In one embodiment, the middle Figure 1 Cross-sectional view of the pole piece in the AA direction.

[0031] Figure 4 Schematic diagram of the tab on the pole piece in one embodiment.

[0032] Figure 5 Schematic diagram of a battery in one embodiment.

[0033] Figure 6 Schematic diagram of an electrode assembly in one embodiment.

[0034] Figure 7 Schematic diagram of an electrode assembly in another embodiment.

[0035] Figure 8 Schematic diagram of a negative electrode plate in one embodiment.

[0036] Figure 9 Schematic diagram of a negative electrode tab on a negative electrode sheet in one embodiment.

[0037] Figure 10 Schematic diagram of a negative electrode tab on a negative electrode sheet in another embodiment.

[0038] Figure 11 Schematic diagram of the connection between part of the electrode assembly and the cover assembly in one embodiment.

[0039] Figure 12 Schematic diagram of a portion of an electrode assembly in one embodiment.

[0040] Description of labels:

[0041] 10. Housing; 11. Cover assembly; 12. First pole; 13. Second pole; 14. Explosion-proof valve; 15. Liquid injection hole; 20. Electrode assembly; 100. Pole piece; 101. Coating area; 102. Uncoated area; 103. Primer; 104. First insulating layer; 105. Second insulating layer; 106. Transition area; 110. Current collector; 120. Active material layer; 130. First insulating portion; 140. Second insulating portion; 150. Tab; 160, current collector body; 200, negative electrode sheet; 210, negative electrode current collector; 220, negative electrode active material layer; 230, negative electrode tab area; 240, negative electrode tab; 241, connection area; 1112, adapter; 1113, first tab welding part; 1114, second tab welding part; 30, first adhesive tape; 31, first adhesive area; 32, non-adhesive area; 33, second adhesive area; 300, diaphragm; 40, second adhesive tape. DETAILED DESCRIPTION

[0042] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0043] It should be understood that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them. They are not used to limit the conditions for the implementation of this solution, so they have no technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed in this solution without affecting the efficacy and purpose of this solution. At the same time, the terms such as "upper", "lower", "left", "right", "middle", "under", "below", "first", "second" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of this solution. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of this solution without substantially changing the technical content.

[0044] The technical solutions of the present invention are further described in detail below with reference to the embodiments and accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0045] The present application provides an electronic device, which includes at least one battery, and the battery is used to provide electrical energy. The electronic device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, and an electric tool, etc. In one embodiment of the present invention, the vehicle is, for example, a new energy vehicle, which may be a pure electric vehicle, a hybrid vehicle, or an extended-range vehicle, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools, and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc.

[0046] The present application also provides a battery that can be used in the above-mentioned electronic device, the battery comprising a housing and an electrode assembly disposed within the housing, the electrode assembly comprising positive and negative electrode sheets and a separator. The present invention does not limit the type and shape of the battery, and the battery may be, for example, a primary battery or a secondary battery. The secondary battery may be, for example, a soft-pack battery, a cylindrical battery, or a square-shell battery, or a sodium-ion secondary battery or a lithium-ion secondary battery. In this embodiment, a lithium-ion secondary battery is used as an example for illustration.

[0047] See also Figure 1 and Figure 2As shown, the present application also provides a pole piece that can be used for the above-mentioned battery. In one embodiment of the present application, the pole piece 100 includes a current collector 110, and the current collector 110 includes a coated area 101 and an uncoated area 102. The coated area 101 includes an active material layer 120, a first insulating part 130, and a second insulating part 140 that are arranged adjacent to each other in sequence along a preset direction Y on at least one side in the thickness direction of the current collector, wherein adjacent refers to direct contact between components, or arranged according to a preset spacing, wherein the preset spacing ranges from 0.1mm to 1mm. In this embodiment, the first insulating part 130 and the second insulating part 140 are adjacent to each other, and the active material layer 120 and the first insulating part 130 can be spaced apart. In other embodiments, the first insulating part 130 may also partially overlap with the active material layer 120, that is, the first insulating part 130 covers a portion of the thinned area of ​​the active material layer 120. In the thickness direction of the current collector 110, the thickness of the first insulating portion 130 is greater than the thickness of the second insulating portion 140. Along the predetermined direction Y, the first insulating portion 130 includes a first insulating layer 104 and a second insulating layer 105 coated on the first insulating layer 104. The width of the uncoated area 102 is W1 mm, and the width of the first insulating portion 130 is W2 mm, satisfying 1.5≤W1 / W2≤10. Compared to providing a single insulating layer, in order to improve the support at the junction of the active material layer and the insulating layer, when a thick insulating layer is provided, the uncoated area is easily torn when bent during winding or lamination. When a thin insulating layer is provided, it cannot provide sufficient support for the uncoated area, and the uncoated area is prone to problems such as flanging and wrinkling. In the present application, by arranging a first insulating part and a second insulating part with a thickness difference between the active material layer and the uncoated area, the first insulating part between the active material layer and the second insulating part can support the uncoated area. When there is a thickness difference between the first insulating part and the second insulating part, when the electrode is used to assemble the bare battery cell for bundling, the thickness from the first insulating part to the second insulating part is excessive, which can disperse stress, reduce wrinkles at the junction of the uncoated area and the second insulating part, or reduce folding of the uncoated area. On the premise of effectively supporting the uncoated area and reducing wrinkles and folding of the uncoated area, the welding area area of ​​the uncoated area and other structures in the battery is ensured to ensure current transmission.

[0048] See also Figures 1 to 2As shown, in one embodiment of the present invention, the value range of W1 is, for example, 9mm-36mm, and the value range of W2 is, for example, 1mm-10mm. By controlling the minimum value of the width of the first insulating portion 130, it is possible to ensure that the stop area of ​​the laser cutting falls on the first insulating portion 130 during the subsequent die-cutting process of the tab. The thicker first insulating portion 130 can reduce the generation of die-cutting burrs and improve the safety of the battery. At the same time, controlling the maximum value of the width of the first insulating portion 130 can avoid the waste of space in the coating area, thereby avoiding reducing the volume energy density of the battery cell. By controlling the width ratio of the uncoated area and the first insulating portion, while effectively supporting the uncoated area and reducing wrinkles and folds in the uncoated area, it is possible to avoid waste caused by excessive space in the uncoated area, and it is also possible to avoid the uncoated area being too small and the uncoated area being welded to other structures in the battery, resulting in a limited welding area that affects the assembly of the uncoated area, thereby ensuring the area of ​​the welding area to ensure current transmission.

[0049] See also Figures 1 to 2 As shown, in one embodiment of the present invention, along the preset direction Y, the width of the second insulating portion 140 is W3 mm, satisfying 1.6≤W1 / W3≤25. In a specific embodiment of the present invention, the value range of W3 is, for example, 1mm-15mm. By controlling the width ratio of the uncoated area 102 and the second insulating portion 140, it is ensured that the second insulating portion 140 can play a sufficient supporting role and transition area, the strength of the uncoated area 102 of the current collector can be further improved, and the wrinkles, collapsed edges, etc. at the junction of the uncoated area 102 or the second insulating portion 140 and the uncoated area 102 can be further reduced, and the flanging and folding of the uncoated area can be reduced. At the same time, the length of the uncoated area and the first insulating portion can be extended to facilitate the matching of battery cells with more tabs.

[0050] See also Figures 1 to 2 As shown, in one embodiment of the present invention, the thickness of the first insulating portion 130 in the thickness direction of the current collector 110 is 10μm-100μm. If the thickness of the first insulating portion 130 is too small, it is not conducive to isolating burrs in subsequent processes, and burrs are easily generated in the subsequent die-cutting process, which is not conducive to improving the safety performance of the battery. If the thickness of the first insulating portion 130 is too large, it may exceed the thickness of the active material layer 120, resulting in curling bulging edges and decreased charge, discharge and cycle performance. Therefore, controlling the thickness of the first insulating portion 130 can reduce burrs and improve the cycle performance of the battery.

[0051] See also Figures 1 to 2As shown, in one embodiment of the present invention, the thickness of the second insulating portion 140 in the thickness direction of the current collector 110 is, for example, 0.5 μm to 9 μm. If the thickness of the second insulating portion 140 is too small, it cannot provide insulation and support. If the thickness of the second insulating portion 140 is too large, it will affect the bending and curling. In addition, too large a thickness may also cause the current collector to curl up, which is not conducive to the winding of the current collector.

[0052] See also Figures 1 to 2 As shown, in one embodiment of the present invention, a thickness gradient exists between the uncoated region 102, the second insulating portion 140, and the first insulating portion 130 of the pole piece 100. During the subsequent bending process, the three regions experience different bending deflections. By adjusting the ratios of W1, W2, and W3, the bending point and the shape of the bending curve can be controlled. This can reduce problems such as folding or tearing in the uncoated region during winding or lamination and welding.

[0053] See also Figure 1 and Figure 3 As shown, in one embodiment of the present invention, a primer layer 103 is further provided between the active material layer 120 and the current collector 110. Along the preset direction Y, one end of the primer layer 103 extends beyond the active material layer 120, wherein the width of one end of the primer layer 103 extending beyond the active material layer 120 is, for example, W4 mm. In a specific embodiment of the present invention, the value range of W4 is, for example, 0.1 mm to 2 mm. The primer layer 103 is, for example, a carbon coating layer. Providing the primer layer 103 beyond the active material layer 120 can avoid direct contact between the active material layer 120 and the current collector 110, thereby increasing the bonding performance between the active material layer 120 and the current collector 110 and reducing the shedding of the active material layer 120. While reducing the folding and wrinkling of the uncoated area and ensuring the welding area, the conductivity between the active material layer 120 and the current collector 110 can also be enhanced.

[0054] See also Figures 1 to 4As shown, in one embodiment of the present invention, the first insulating layer 104 is spaced apart from the primer layer 103, and the second insulating portion 140 and the first insulating layer 104 are obtained by applying the same slurry at one time, that is, the first insulating layer 104 not covered by the second insulating layer 105 is defined as the second insulating portion 140, and the thickness, composition, etc. of the second insulating portion 140 are completely consistent with the first insulating layer 104. There is a preset spacing G mm between the first insulating layer 104 and the primer layer 103. In a specific embodiment of the present invention, the value range of G is, for example, 0.5 mm-4 mm. By setting the preset spacing G, the mutual dissolution caused by direct contact between the first insulating layer 104 and the primer layer 103 can be avoided. At the same time, the second insulating layer 105 on the preset spacing G will be slightly thinner than other positions (not shown in the figure), so as to avoid the interpenetration of the second insulating layer 105 and the active material layer 120. By providing the first insulating layer 104 and the second insulating layer 105, it is possible to ensure that a first insulating portion and a second insulating portion with a thickness difference are formed, and to ensure that the thickness from the first insulating portion to the second insulating portion is excessive, so as to disperse stress, reduce wrinkles at the junction of the uncoated area and the second insulating portion, or reduce folding of the uncoated area. Moreover, on the premise of effectively supporting the uncoated area and reducing wrinkles and folding of the uncoated area, it is possible to avoid the first insulating layer 104 from falling off, and at the same time reduce burrs and bulging problems.

[0055] See also Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the current collector 110 is, for example, a positive electrode current collector, and the current collector 110 is, for example, aluminum foil, and the thickness of the current collector 110 is, for example, 5 μm-20 μm. Furthermore, the thickness of the current collector 110 is, for example, 10 μm-15 μm. The active material layer 120, the first insulating portion 130, and the second insulating portion 140 are disposed on one surface of the current collector, or are disposed on both surfaces of the current collector 110.

[0056] See also Figures 1 to 3 As shown, in one embodiment of the present invention, the first insulating layer 104 includes, for example, a first binder and an inorganic insulating material. The first binder may be, for example, a water-based binder, and may include at least one of polyacrylic acid (PAA), styrene butadiene rubber (SBR), polyvinyl alcohol (PVA), polyacrylamide (PAM), methyl cellulose and its salts, chitosan and its salts, alginic acid and its salts, and the inorganic insulating material may include, for example, at least one of boehmite, aluminum oxide, titanium dioxide, zirconium dioxide, zinc oxide, barium sulfate, boron nitride, aluminum nitride, or magnesium nitride. In one embodiment of the present invention, the mass ratio of the first binder to the inorganic insulating material is, for example, 8-30:70-92.

[0057] See also Figures 1 to 3 As shown, in one embodiment of the present invention, the second insulating layer 105 includes, for example, a second binder and an inorganic insulating material. The second binder is, for example, an oily binder, and further includes, for example, at least one of polyvinylidene fluoride or an oily polyimide (PI). The oily polyimide includes, for example, at least one of homophenyl polyimide or biphenyl / ether anhydride polyimide. The inorganic insulating material includes, for example, at least one of boehmite, aluminum oxide, titanium dioxide, zirconium dioxide, zinc oxide, barium sulfate, boron nitride, aluminum nitride, or magnesium nitride. In one embodiment of the present invention, the mass ratio of the second binder to the inorganic insulating material is, for example, 8-30:70-92. In this embodiment, the median particle size Dv50 of the inorganic insulating material in the second insulating layer 105 is greater than the median particle size Dv50 of the inorganic insulating material in the first insulating layer 104. This ensures a thinner first insulating layer 104 during the preparation process and improves the support of the second insulating layer 105. The median particle size Dv50 refers to the particle size value corresponding to the cumulative distribution reaching 50% in the particle size distribution curve. The insulating layer obtained by using the inorganic insulating material and the binder can improve the support effect and insulation of the insulating portion.

[0058] See also Figures 1 to 3 As shown, in one embodiment of the present invention, the active material layer 120 includes an active material, a conductive agent, and a third binder. The active material, for example, includes a lithium-containing phosphate material, such as at least one selected from lithium iron phosphate (LiFePO4) or lithium iron manganese phosphate. The conductive agent, for example, is selected from conductive carbon black, acetylene black, nanometal powder, graphene, carbon nanotubes, or carbon nanofibers, or a combination of two or more in any proportion. The third binder is selected from one or more mixtures of polyvinylidene fluoride (PVDF), oily polyimide, polyvinylidene fluoride-hexafluoropropylene, or polytetrafluoroethylene. In one embodiment of the present invention, the mass ratio of the active material, conductive agent, and third binder is, for example, 90-98:1-5:1-5. The present invention does not limit the thickness of the active material layer 120 on the current collector side; the thickness is selected based on the battery design requirements. In this embodiment, the thickness of the active material layer 120 on the current collector side is, for example, greater than or equal to the thickness of the first insulating portion 130 on the current collector side.

[0059] See also Figures 1 to 3As shown, in one embodiment of the present invention, the primer layer 103 includes, for example, a carbon material, a fourth binder, and a neutralizer. The carbon material includes at least one of conductive carbon black, graphite, graphene, or carbon nanotubes. The fourth binder includes at least one of polyacrylic acid, styrene-butadiene rubber, polyvinyl alcohol, polyacrylamide, methylcellulose and its salts, chitosan and its salts, alginic acid and its salts. The neutralizer includes at least one of lithium hydroxide, sodium hydroxide, calcium hydroxide, or ammonia water. The thickness of the primer layer 103 is, for example, 0.1 μm to 2 μm. Controlling the thickness of the primer layer 103 improves conductivity while reducing the impact on energy density. In one embodiment of the present invention, the mass ratio of the carbon material, the fourth binder, and the neutralizer is, for example, 40-53:45-55:2-5.

[0060] See also Figures 1 to 3 As shown, in one embodiment of the present invention, when forming the primer layer 103 and the first insulating layer 104, the first binder and the inorganic insulating material are dispersed in a first solvent in a mass ratio to obtain a first slurry. The carbon material, the fourth binder and the neutralizer are dispersed in a second solvent in a mass ratio to obtain a carbon slurry. The first solvent and the second solvent include, for example, aqueous solvents such as deionized water or high-purity water. The direction perpendicular to the preset direction Y is defined as the vertical direction X. During the coating process, the first slurry and the carbon slurry are simultaneously formed on at least one side of the current collector 110 along the vertical direction X at a preset spacing by gravure coating, and dried to obtain the first insulating layer 104 and the primer layer 103. The first insulating layer 104 and the primer layer 103 can also be customized at the current collector supplier stage according to usage requirements.

[0061] See also Figures 2 to 3 As shown, in one embodiment of the present invention, when forming the second insulating layer 105 and the active material layer 120, the second binder and the inorganic insulating material are dispersed in a third solvent to obtain a second slurry, and the active material, the third binder and the conductive agent are dispersed in a fourth solvent to obtain an active slurry. Wherein, the third solvent and the fourth solvent include, for example, organic solvents such as N-methylpyrrolidone (NMP). During the coating process, the second slurry and the active slurry are simultaneously coated on a portion of the first insulating layer 104 and the primer layer 103 by roller coating, spraying or slit coating, and dried to obtain the second insulating layer 105 and the active material layer 120.

[0062] See also Figure 1 and Figure 4As shown, in one embodiment of the present invention, the electrode sheet 100 further includes a tab 150, which protrudes from the current collector body 160 along a predetermined direction. The current collector body 160 includes an area covered by the active material layer 120 and a transition region 106 located between the active material layer 120 and the tab. Along the vertical direction X, the transition region 106 extends from one end of the current collector to the other. The second insulating portion 140 and a portion of the first insulating portion 130 are located on the surface of the tab 150, and another portion of the first insulating portion 130 is located in the transition region 106. In this case, the height of the tab 150 includes the dimensions of the second insulating portion 140 and a portion of the first insulating portion 130 located on the tab 150. Along the predetermined direction Y, the transition region 106 is away from the side of the active material layer 120 and is located within the overlapping range of the orthographic projections of the first insulating layer 104 and the second insulating layer 105 in the thickness direction of the current collector 110.

[0063] See also Figures 3 and 4 As shown, in one embodiment of the present invention, after forming the active material layer 120 and the second insulating layer 105, the tab 150 is obtained by die-cutting the uncoated area 102, the second insulating portion 140, and a portion of the first insulating portion 130. The die-cutting stop position is recorded as the shoulder B of the tab 150. The tab 150 extends from the shoulder B to the side of the uncoated area 102 away from the active material layer 120. By stopping the die-cutting position at the first insulating portion 130 and being located within the overlapping range of the first insulating layer 104 and the second insulating layer 105, the thickness of the insulating portion at the die-cutting stop position is greater, which can reduce burrs and improve safety performance.

[0064] See also Figures 5 to 7As shown, in one embodiment of the present invention, the battery further includes a housing 10 having an upper opening, an electrode assembly disposed within the housing 10, and a cover assembly 11 that seals the upper opening. The tabs of the electrode assembly 20 are electrically connected to the posts on the housing 10. The shape of the housing 10 matches that of the electrode assembly 20, and the material of the housing 10 is, for example, aluminum, steel, or a flexible housing. The housing 10 is a chamber with an upper opening for accommodating the electrode assembly 20. Specifically, after the electrode assembly 20 is placed within the housing 10 through the upper opening, the housing 10 is sealed with the cover assembly 11. The cover assembly 11 is provided with a first post 12, a second post 13, an explosion-proof valve 14, and an injection port 15. The electrolyte is injected through the injection port 15, and the injection port 15 is then sealed. The first post 12 and the second post 13 have opposite polarities, and are respectively positive or negative. The present invention does not limit the specific polarity of the first post 12 and the second post 13. The first electrode post 12 is electrically connected to the tab of the same polarity on the electrode assembly 20, and the second electrode post 13 is electrically connected to the tab of the same polarity on the electrode assembly 20. In this embodiment, the positions of the first electrode post 12 and the second electrode post 13 are not limited and can be located at the same end of the housing or at both ends of the housing, depending on the position of the tab on the electrode assembly 20 or design requirements.

[0065] See also Figure 5 As shown, in one embodiment of the present invention, when the first and second poles 12 and 13 are disposed at one end of the housing, the explosion-proof valve 14 and the injection hole 15 are disposed between the first and second poles 12 and 13. For example, the explosion-proof valve 14 is disposed midway between the first and second poles 12 and 13, with a predetermined distance therebetween. The injection hole 15 is disposed between the explosion-proof valve 14 and the first pole 12, or between the explosion-proof valve 14 and the second pole 13. That is, the explosion-proof valve 14, the injection hole 15, the first and second poles 12 and 13 are spaced apart from each other. The explosion-proof valve 14 can activate its ventilation function when the battery cell is operating normally, allowing air to flow inside and outside the battery cell while preventing particulate matter from flowing. In the event of thermal runaway of the battery cell, when the pressure difference between the inside and outside of the battery cell reaches a predetermined explosion-proof value, the explosion-proof valve opens, allowing both gas and solids to be discharged from the inside of the battery cell to the outside of the battery cell through the explosion-proof valve, thereby improving the safety performance of the battery cell.

[0066] See also Figures 6 and 7As shown, in one embodiment of the present invention, the electrode assembly 20 includes a positive electrode sheet and a negative electrode sheet 200 and a separator 300. The positive electrode sheet is selected from the above-mentioned electrode sheet 100. The separator 300 is arranged between the positive electrode sheet and the negative electrode sheet 200 to prevent the positive electrode sheet and the negative electrode sheet 200 from contacting each other and causing safety problems. An electrolyte (not shown in the figure) is filled between the positive electrode sheet, the negative electrode sheet 200 and the separator 300, and between the electrode assembly 20 and the shell to conduct ions between the positive and negative electrode sheets. The electrolyte is any applicable lithium-ion battery electrolyte. The stacking method of the positive and negative electrode sheets is not specifically limited in this application, and is selected according to the specific manufacturing requirements.

[0067] In one embodiment of the present invention, the electrolyte includes, for example, an organic solvent and a lithium salt. The organic solvent is selected from any one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl acetate (EA), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), or diethyl carbonate (DEC). The lithium salt is selected from any one or more of lithium bis(fluorosulfonyl)imide (LiFSi), lithium difluorophosphate (LiPO2F2), lithium hexafluorophosphate (LiPF6), or lithium tetrafluoroborate (LiBF4). In one embodiment of the present invention, the lithium salt is selected from lithium hexafluorophosphate, for example, and the organic solvent is selected from a mixture of ethylene carbonate, ethyl methyl carbonate, diethyl carbonate, and propylene carbonate. Ethylene carbonate, ethyl methyl carbonate, diethyl carbonate and propylene carbonate are mixed, for example, in a volume ratio of 1:1:1:1, and fully dried LiPF6 is dissolved in a mixed organic solvent in an argon atmosphere glove box with a water content of less than 10 ppm. After mixing evenly, an electrolyte is obtained, wherein the concentration of LiPF6 is, for example, 1 mol / L.

[0068] See also Figures 6 and 7As shown, in one embodiment of the present invention, the electrode sheet 100, the negative electrode sheet 200, and the separator are formed into the electrode assembly 20 by, for example, winding or laminating. The lamination can be, for example, a stacked laminate or a Z-shaped laminate, and this application does not impose any specific restrictions. The separator 300 can be, for example, a polyethylene film (PE), a polypropylene film (PP), a glass fiber film, a polyethylene film, or a composite film. In this application, the thickness of the separator 300 is not limited, and can be any thickness that meets the requirements of use.

[0069] See also Figure 8 As shown, in one embodiment of the present invention, the negative electrode plate 200 includes a negative electrode current collector 210 and a negative electrode active material layer 220 coated on at least one surface of the negative electrode current collector 210. That is, the negative electrode current collector 210 has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer 220 can be provided on any one or both of the two surfaces in the thickness direction of the negative electrode current collector 210. The negative electrode current collector 210 can be a copper foil current collector, and the thickness of the current collector is, for example, 5μm-20μm. The negative electrode current collector 210 can also be a composite current collector, which includes a polymer matrix and copper layers located on the upper and lower surfaces of the polymer matrix. The polymer matrix can be polyethylene terephthalate, polypropylene, polyimide, polystyrene or polyamide, etc.

[0070] See also Figure 8 As shown, in one embodiment of the present invention, on the negative electrode current collector 210, the area coated with the negative electrode active material layer 220 is defined as the electrode sheet area, and the area of ​​the negative electrode current collector 210 not coated with the negative electrode active material layer 220 is defined as the negative electrode tab area 230, which is used to form the negative electrode tab. The electrode sheet area and the negative electrode tab area 230 are adjacent to each other. The negative electrode active material layer 220 may include, for example, a negative electrode active material, a negative electrode binder, a thickener, and a negative electrode conductive agent. The negative electrode active material may be selected from, for example, soft carbon, hard carbon, artificial graphite, silicon, silicon oxide compounds, silicon carbon compounds, or lithium titanate, or a combination of at least two. The negative electrode binder may be selected from, for example, one or more of polypropylene, polyacrylic acid and its derivatives, or styrene-butadiene rubber. The negative electrode conductive agent may be selected from, for example, one or more of conductive carbon black, acetylene black, carbon nanotubes, and graphene. The thickener may be selected from, for example, sodium carboxymethyl cellulose. This application does not limit the mass ratio of the negative electrode active material, negative electrode binder, thickener, and negative electrode conductive agent; the ratios may be selected based on the preparation requirements. In one embodiment of the present application, the mass ratio of the negative electrode active material, the negative electrode binder, the thickener, and the negative electrode conductive agent is, for example, 90-97:1-5:1-2:1-3.

[0071] See also Figure 9 and Figure 10As shown, in one embodiment of the present invention, the negative electrode plate 200 includes a plurality of negative electrode tabs 240, and part of the negative electrode active material layer 220 covers at least part of the surface of the negative electrode tab 240; or a connection area 241 is provided between the negative electrode tab 240 and the negative electrode active material layer 220, and the connection area 241 is continuously provided in the negative electrode tab area 230, that is, the negative electrode active material layer 220 is not provided on the connection area 241, and the negative electrode active material layer 220 does not cover the negative electrode tab 240.

[0072] See also Figure 4 、 Figures 10 to 12 As shown, in one embodiment of the present invention, the electrode sheet 100, the negative electrode sheet 200 and the separator 300 are made into an electrode assembly 20 by, for example, winding or laminating. The electrode assembly 20 includes a main body 1 and a tab 150 and a negative tab 240 located at one end of the main body 1. The tab 150 is a positive tab. Among them, the main body 1 is a portion formed by the shoulder B of the tab as a stack. Two electrode assemblies 20 are arranged oppositely in the shell 10. Each group of electrode assemblies 20 is provided with a tab 150 and a negative tab 240 at one end facing the cover assembly 11. The tab 150 and the negative tab 240 are bent and fixedly connected to the adapter 1112 of the cover assembly 11. Among them, two groups of adapters 1112 are provided on the cover assembly 11, which are respectively connected to the positive tab and the negative tab. The width direction W of the adapter plate 1112 includes a first tab weld portion 1113 and a second tab weld portion 1114 symmetrically arranged along the length direction W of the adapter plate 1112. There are two groups of electrode assemblies 20. The tabs 150 of one group of electrode assemblies 20 and the tabs 150 of the other group of electrode assemblies 20 are bent relative to each other and then welded to the first tab weld portion 1113 and the second tab weld portion 1114 of one adapter plate 1112. The negative electrode tabs 240 of one group of electrode assemblies 20 and the negative electrode tabs 240 of the other group of electrode assemblies 20 are bent relative to each other and then welded to the first tab weld portion 1113 and the second tab weld portion 1114 of the other group of adapter plate 1112. The two groups of electrode assemblies 20 are then bent relative to each other and then installed in the housing 10.

[0073] See also Figure 4 、 Figures 10 to 12As shown, in one embodiment of the present invention, the tab 150 includes an uncoated area 102, a second insulating portion 140 and a portion of the first insulating portion 130 provided on the same side of the tab 150 in the thickness direction. The uncoated area 102 is fixedly connected to the welding portion of the adapter 1112, and the second insulating portion 140 and at least a portion of the first insulating portion 130 are connected between the main body 1 and the uncoated area 102. Combined with the thickness of the first insulating portion 130 and the second insulating portion 140, a good support effect can be provided. At the same time, when the bent tab 150 is welded to the tab welding portion, the bending of the tab 150 is not affected, and problems such as tab folding are reduced. A first adhesive tape 30 is applied to the side of the tab 150 facing away from the cover plate assembly 11 to protect it. The first adhesive tape 30 includes a first adhesive area 31, a second adhesive area 33, and a non-adhesive area 32 located between the first and second adhesive areas 31 and 33. The first adhesive area 31 covers the body 1, and the second adhesive area 33 covers the uncoated area 102. In the thickness direction of the electrode assembly, the orthographic projections of the first and second insulating portions 130 and 140 are completely within the non-adhesive area 32, thereby preventing the insulation from falling off when the tab is static or during assembly. A second adhesive tape 40 covers the negative tab 240, located on the side of the tab facing away from the cover plate assembly 11, to protect it. The adhesive tape enhances safety against foil leakage, and the non-adhesive area covers the insulation, preventing it from falling off. The tape also provides support, preventing the tab from being inserted into or torn.

[0074] Hereinafter, the present invention will be explained in more detail by citing examples, which should not be construed as limiting. Appropriate modifications may be made within the scope consistent with the gist of the present invention, all of which fall within the technical scope of the present invention.

[0075] Example 1

[0076] Preparation of the positive electrode: Polyacrylic acid and boehmite were dispersed in deionized water at a mass ratio of 12:88 to obtain a first slurry. Conductive carbon black, polyacrylic acid, and calcium hydroxide were dispersed in deionized water at a mass ratio of 45:52:3 to obtain a carbon slurry. Polyvinylidene fluoride and boehmite were dispersed in NMP at a mass ratio of 12:88 to obtain a second slurry. LiFePO4, polyvinylidene fluoride, and acetylene black were dispersed in NMP at a mass ratio of 97:2:1 to obtain an active slurry.

[0077] The first slurry and carbon slurry are simultaneously applied to one side of the current collector via gravure coating and dried to form the first insulating layer and primer layer. The second slurry and active material slurry are simultaneously applied to portions of the first insulating layer and primer layer via roller coating and dried to form the second insulating layer and active material layer. The positive electrode sheet is then produced through cold pressing, slitting, die-cutting, and sheeting.

[0078] On the positive electrode sheet, along the predetermined direction, the width W1 of the uncoated area is 9 mm, the width W2 of the first insulating portion is 6 mm, the width W3 of the second insulating portion is 5 mm, the width of one end of the primer layer protruding from the active material layer is 0.2 mm, and the predetermined spacing G between the first insulating layer and the primer layer is 0.5 mm. The thickness of the first insulating portion is 30 μm, the thickness of the second insulating portion is 5 μm, and the thickness of the primer layer is 1 μm.

[0079] Preparation of the negative electrode sheet: Artificial graphite, conductive carbon black, sodium carboxymethyl cellulose, and styrene-butadiene rubber are mixed in a mass ratio of 96:1:1:2, deionized water is added, and the mixture is mixed thoroughly in a vacuum mixer to obtain a negative electrode slurry. The negative electrode slurry is coated on a 6μm thick copper foil and transferred to an oven for drying. After roller pressing, slitting, die-cutting, and cutting, the negative electrode sheet is obtained.

[0080] Preparation of electrolyte: Ethylene carbonate, ethyl methyl carbonate, diethyl carbonate and propylene carbonate are mixed in a volume ratio of 1:1:1:1. In an argon atmosphere glove box with a water content of less than 10 ppm, fully dried LiPF6 is dissolved in a mixed organic solvent, and the mixture is mixed evenly to obtain an electrolyte, wherein the concentration of LiPF6 is, for example, 1 mol / L.

[0081] Selection of diaphragm: Polyethylene with a thickness of 9 μm is used as the diaphragm.

[0082] Battery Preparation: The positive electrode sheet, separator, and negative electrode sheet are stacked in sequence and wound, with the separator positioned between the positive and negative electrodes to provide isolation. Except for the innermost and outermost circles, each circle of the negative electrode sheet has a tab, resulting in a wound bare cell. The bare cell is then placed in an aluminum casing, fitted with a top cover assembly, and then electrolyte is injected and sealed to create a lithium-ion battery.

[0083] Example 2

[0084] The width W1 of the uncoated area is 36 mm, the width W2 of the first insulating portion is 6 mm, and the remaining operations are the same as those in Example 1.

[0085] Example 3

[0086] The width W1 of the uncoated area is 60 mm, the width W2 of the first insulating portion is 6 mm, and the remaining operations are the same as those in Example 1.

[0087] Example 4

[0088] The width W1 of the uncoated area is 25 mm, the width W3 of the second insulating portion is 5 mm, and the remaining operations are the same as those in Example 1.

[0089] Example 5

[0090] The width W1 of the uncoated area is 25 mm, the width W3 of the second insulating portion is 1 mm, and the remaining operations are the same as those in Example 1.

[0091] Example 6

[0092] The width W1 of the uncoated area is 25 mm, the width W3 of the second insulating portion is 15 mm, and the remaining operations are the same as those in Example 1.

[0093] Example 7

[0094] The width W1 of the uncoated area is 25 mm, the width W3 of the second insulating portion is 20 mm, and the remaining operations are the same as those in Example 1.

[0095] Example 8

[0096] The width W1 of the uncoated area is 28 mm, the width W3 of the second insulating portion is 0.8 mm, and the remaining operations are the same as those in Example 1.

[0097] Comparative Example 1

[0098] The width W1 of the uncoated area is 0 mm, the width W2 of the first insulating portion is 6 mm, and the remaining operations are the same as those in Example 1.

[0099] Comparative Example 2

[0100] The width W1 of the uncoated area is 72 mm, the width W2 of the first insulating portion is 6 mm, and the remaining operations are the same as those in Example 1.

[0101] In one embodiment of the present invention, in order to obtain the thickness of the first insulating portion and the second insulating portion on the current collector, the electrode sheet is measured by scanning electron microscope (SEM). Figure 1 The cross section in the AA direction is scanned, and the maximum thickness of the first insulating portion and the second insulating portion along the thickness direction of the current collector is recorded as the thickness of the first insulating portion and the second insulating portion.

[0102] In one embodiment of the present invention, in order to obtain the tab wrinkle performance, after obtaining the bare battery cell, the distance value from the side of each tab away from the active material layer to the active material layer is tested by a camera (if it is the design value after the battery is disassembled, for the tabs of equal height, the maximum value of the width of the uncoated area, the first insulating part and the second insulating part is taken. If it is a tab of unequal height, first measure it in the initial state, then straighten the tab with force, take the maximum and minimum values ​​of each uncoated area for comparison, and judge its tab deviation value), and obtain the average value of the difference, and define the average value as the tab deviation value (if the deviation value of the uncoated area is obtained, the distance from the side of the uncoated area of ​​each layer away from the active material layer to the side adjacent to the active material layer is obtained by a camera). The tab deviation value is used to characterize the tab wrinkle performance. The smaller the tab deviation value, the less wrinkles the tab has. Among them, in the present application, the uncoated areas of the single batteries of Examples 1-8 and Comparative Examples 1-2 are all set at equal heights.

[0103] In one embodiment of the present invention, in order to obtain the folding condition of the tab, after obtaining the bare battery cell, the orthographic projection area of ​​each tab on the plane where the current collector is located is obtained by a CCD camera, which is recorded as S1, and the orthographic projection area of ​​each tab on the plane where the current collector is located after it is flattened is recorded as S2 (if the folding condition of the uncoated area is obtained, the orthographic projection area of ​​each layer of the uncoated area on the plane where the current collector is located, and the orthographic projection area of ​​each layer of the uncoated area on the plane where the current collector is located after it is flattened are obtained by a CCD camera), the calculation error = (S2-S1) / S2×100%, the tab with an error greater than 5% is defined as a tab with folding, and the ratio of the number of tab layers with folding to the total number of tab layers is calculated.

[0104] Table 1. Some characteristics and properties of the positive electrode sheets in Examples 1-3 and Comparative Examples 1-2

[0105]

[0106] As shown in Table 1, a comparison of Examples 1-3 and Comparative Example 2 shows that when W1 / W2 satisfies a range of 1.5-10, the uncoated area has a low folding ratio, indicating less wrinkling and folding in the uncoated area. While the folding ratio slightly increases in Example 3 compared to Example 2, it is still less than 0.5% overall. This is due to the larger width of the uncoated area, which prevents the first insulating portion from providing effective support, leading to increased folding and wrinkling in the uncoated area. In Comparative Example 1, when the uncoated area is not provided, the tab has no weldable area, which does not meet battery manufacturing requirements. When the width of the uncoated area is too large, the first insulating portion cannot provide effective support, making folding and wrinkling in the uncoated area more likely to occur, increasing the folding ratio. Furthermore, the excessive width of the uncoated area affects welding, resulting in a failure to meet battery manufacturing requirements. Therefore, controlling the width ratio of the uncoated area to the first insulating portion within a set range and simultaneously controlling the width of the uncoated area can reduce folding and wrinkling in the uncoated area while meeting battery manufacturing requirements.

[0107] Table 2. Some characteristics and properties of the positive electrode sheets in Examples 1, 4-7

[0108]

[0109] Please refer to Table 1. Comparing Examples 4-8, it can be seen that as the ratio of the width W1 / W3 of the uncoated area and the second insulating part increases, the deviation value of the uncoated area first decreases and then increases, and the proportion of folding of the uncoated area increases. When the ratio of W1 / W3 is small, the proportion of folding of the uncoated area is small, but the supporting effect of the second insulating part is weakened, which will lead to an increase in undesirable conditions such as wrinkles and folding in the uncoated area. When the ratio of W1 / W3 is large, the width of the second insulating part is small, and the transition from the first insulating part to the second insulating part is too small, which makes the uncoated area easy to fold and the uncoated area deviate. Therefore, the ratio of the width of the uncoated area and the second insulating part is controlled within a set range to reduce undesirable conditions such as folding and wrinkling of the uncoated area and improve the safety of the battery.

[0110] In summary, the electrode, battery and electronic device provided by the present invention provide a first insulating portion and a second insulating portion with a thickness difference between the active material layer and the uncoated area. The first insulating portion between the active material layer and the second insulating portion can support the uncoated area. When there is a thickness difference between the first insulating portion and the second insulating portion, when the electrode is used to assemble the bare battery cell for bundling, the thickness from the first insulating portion to the second insulating portion is excessive, which can disperse stress, reduce wrinkles at the junction of the uncoated area and the second insulating portion, or reduce folding of the uncoated area. By controlling the width ratio of the uncoated area and the first insulating portion, on the premise of effectively supporting the uncoated area and reducing wrinkles and folding of the uncoated area, the waste of space caused by excessive uncoated area can be avoided, and the waste caused by excessive uncoated area can also be avoided. When the uncoated area is welded to other structures in the battery, the limited welding area affects the assembly of the uncoated area, thereby ensuring the area of ​​the welding area to ensure the transmission of current; and by controlling the width ratio of the uncoated area and the first insulating part, it is possible to ensure that the cutoff area of ​​the laser cutting falls on the first insulating part during the die-cutting process, thereby reducing the generation of die-cutting burrs and improving the safety of the battery; by controlling the width ratio of the uncoated area and the second insulating part, while ensuring sufficient support, the length of the entire pole ear can be extended, which is convenient for matching battery cells with more pole ears; by setting a primer layer separated from the first insulating layer, the interpenetration of the insulating layer and the active material layer can be avoided, the falling of the insulating layer can be avoided, the shedding of the active material layer can be reduced, and the conductivity between the active material layer and the current collector can be enhanced.

[0111] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept, such as the technical solutions formed by the mutual replacement of the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

[0112] Except for the technical features described in the specification, the remaining technical features are known technologies to those skilled in the art. In order to highlight the innovative features of the present invention, the remaining technical features will not be described here in detail.

Claims

1. A pole piece, characterized in that: include: a current collector, the current collector comprising a coated area and an uncoated area, the coated area comprising an active material layer, a first insulating portion, and a second insulating portion disposed in sequence and adjacent to each other along a preset direction and on at least one side in a thickness direction of the current collector; In the thickness direction of the current collector, the thickness of the first insulating portion is greater than the thickness of the second insulating portion, and the first insulating portion includes a first insulating layer and a second insulating layer coated on the first insulating layer; Along the preset direction, the width of the uncoated area is W1 mm, and the width of the first insulating portion is W2 mm, satisfying 1.5≤W1 / W2≤10.

2. The pole piece according to claim 1, characterized in that: The pole piece also includes a pole ear, which protrudes from the current collector body along the preset direction. The current collector body includes the active material layer covering area and a transition zone located between the active material layer and the pole ear. The transition zone extends from one end of the current collector to the other end perpendicular to the preset direction. The second insulating portion and part of the first insulating portion are located on the surface of the pole ear, and another part of the first insulating portion is located in the transition zone.

3. The pole piece according to claim 1, characterized in that: Along the preset direction, the width of the second insulating portion is W3 mm, satisfying 1.6≤W1 / W3≤25; or, The value range of W1 is 9mm-36mm.

4. The pole piece according to claim 1, characterized in that: The pole piece further includes a primer layer disposed between the active material layer and the current collector; Along the preset direction, one end of the primer layer extends beyond the active material layer, and the width of the one end of the primer layer extending beyond the active material layer is 0.1 mm to 2 mm.

5. The pole piece according to claim 4, characterized in that: The active material layer includes an active material, and the active material includes a lithium-containing phosphate material; the materials of the first insulating portion and the second insulating portion include an inorganic insulating material and a binder.

6. The pole piece according to claim 4, characterized in that: Along the preset direction, the first insulating layer and the primer layer are spaced apart from each other; The second insulating portion and the first insulating layer are obtained by coating the same slurry at one time.

7. A battery, characterized in that: At least: A shell having an upper opening; an electrode assembly disposed within the housing; as well as A cover plate assembly with a sealed upper opening, the cover plate assembly comprising a transition piece, wherein the width direction of the transition piece comprises a first tab welding portion and a second tab welding portion symmetrically arranged along the length direction of the transition piece; The electrode assembly is formed by stacking a positive electrode sheet, a separator and a negative electrode sheet and then winding or laminating them, and the positive electrode sheet is the electrode sheet according to any one of claims 1 to 6; Along a preset direction, the electrode assembly includes a main body and a tab, wherein the tab includes an uncoated area and a second insulating portion and a portion of the first insulating portion provided on the same side of the tab in a thickness direction; There are two groups of electrode assemblies. The tabs of one group of electrode assemblies and the tabs of the other group of electrode assemblies are bent relative to each other and then welded to the first tab welding portion and the second tab welding portion of the adapter sheet respectively.

8. The battery according to claim 7, characterized in that The thickness of the first insulating portion is 10 μm-100 μm, or the thickness of the second insulating portion is 0.5 μm-9 μm.

9. The battery according to claim 7, characterized in that The electrode assembly includes a first tape, which is arranged on the side of the tab facing away from the cover plate assembly. The first tape includes a first adhesive area, a second adhesive area, and a non-adhesive area between the first adhesive area and the second adhesive area. The first adhesive area covers the main body, and the second adhesive area covers the uncoated area. In the thickness direction of the electrode assembly, the orthographic projections of the first insulating part and the second insulating part are completely located in the non-adhesive area.

10. An electronic device, characterized in that: A battery comprising the battery according to any one of claims 7 to 9.

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