Pole piece structure and battery

Abstract

The utility model discloses a pole piece structure and a battery, the pole piece structure comprises a pole piece, the pole piece is provided with two large surfaces and an end surface, the two large surfaces are oppositely arranged, the end surface is connected with the two large surfaces, and a puncture-proof part is arranged at the joint of the end surface and the large surfaces so as to be in flexible contact with a diaphragm or other pole pieces. The battery comprises a diaphragm and at least two pole piece structures, the pole pieces are positive pole pieces or negative pole pieces, and the diaphragm is arranged between the positive pole pieces and the negative pole pieces. The anti-puncture part is arranged at the joint of the end surface and the large surface, so that an excessively sharp right-angle area can be prevented from being formed at the edge of the ending part of the pole piece, and a diaphragm is prevented from being punctured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery production, and in particular to a pole piece structure and a battery. BACKGROUND

[0002] At present, among many potential high-performance negative electrode materials, silicon-based materials are increasingly widely used due to their excellent theoretical capacity (far more than several times of traditional graphite negative electrode), lower lithium intercalation potential (favorable to improve battery energy density), and good environmental compatibility. However, a major challenge faced by silicon-based materials in practical application is the huge volume change (more than 300%) during charging and discharging. This characteristic leads to easy expansion and contraction of the negative electrode structure, and thus causes a series of problems.

[0003] Specifically, in the production process of lithium ion batteries, the negative pole piece is usually prepared by cutting a large piece of negative electrode material into a small piece with a specific shape and size. In the cutting process, in order to ensure the size accuracy and edge neatness of the pole piece, a sharp cutter is usually used for cutting, which can cause the formation of a right-angle region at the edge of the end of the pole piece. The repeated expansion of the negative pole piece during use can make the right-angle region at the edge of the end of the pole piece too sharp, and these sharp edges can pierce the separator due to vibration or internal pressure changes during battery operation, causing the positive and negative electrodes to directly contact and form an internal short circuit.

[0004] Therefore, there is an urgent need for a pole piece structure and a battery to overcome the above-mentioned defects. INNOVATION CONTENT

[0005] In order to overcome at least one of the defects of the prior art described above, one of the purposes of the present application is to provide a pole piece structure which can avoid the formation of sharp corners at the edge of the end of the pole piece to pierce the separator by providing a piercing prevention part at the connection between the large surface and the end surface.

[0006] The second purpose of the present application is to provide a battery which can avoid the formation of sharp corners at the edge of the end of the pole piece to pierce the separator between the positive and negative pole pieces by providing a piercing prevention part at the connection between the large surface and the end surface of the pole piece.

[0007] One of the technical solutions adopted by the present application to solve the problems is:

[0008] A pole piece structure, comprising a pole piece, the pole piece having two large surfaces and an end surface, the two large surfaces being oppositely arranged, and the end surface connecting the two large surfaces, a piercing prevention part being provided at the connection between the end surface and the large surface, to make flexible contact with the separator or other pole piece.

[0009] As a preferred technical solution of the present application, the end face and the large face are connected at a right angle and form a right-angle connecting area, a protective layer is arranged on the right-angle connecting area, and the protective layer extends from the large face to the end face; and the protective layer forms the puncture-preventing part.

[0010] As a preferred technical solution of the present application, the two large faces are a first large face and a second large face, respectively, and the first large face and the second large face form a first right-angle connecting area and a second right-angle connecting area with the end face, respectively, and the first right-angle connecting area and the second right-angle connecting area are both provided with the protective layer.

[0011] As a preferred technical solution of the present application, the protective layer includes a first protective segment, a second protective segment, and a third protective segment, the first protective segment covers the edge of the first large face, the second protective segment covers the end face, the third protective segment covers the edge of the second large face, and the second protective segment connects the first protective segment and the third protective segment.

[0012] As a preferred technical solution of the present application, the protective layer is insulating adhesive paper, the thickness of the insulating adhesive paper is H, the value range of H is 20-60 μm, and the width of the insulating adhesive paper along the length direction of the large face is W, and the value range of W is 5-15 mm.

[0013] As a preferred technical solution of the present application, the end face and the large face are connected at an inclined plane, and the two ends of the inclined plane form an obtuse-angle connecting area with the end face and the large face, respectively; and the obtuse-angle connecting area forms the puncture-preventing part.

[0014] As a preferred technical solution of the present application, the end face and the large face are connected at a circular-arc surface, and the circular-arc surface forms the puncture-preventing part.

[0015] As a preferred technical solution of the present application, the pole piece includes a current collector and an active material coating, the active material coating is arranged on both sides of the current collector, the large face is located on the side of the active material coating away from the current collector, the active material coating includes a main body area and a thinning area, the main body area is located in the middle of the current collector, the thinning area is located at the edge of the current collector, and the thickness of the thinning area gradually decreases from the side close to the main body area to the side away from the main body area, so that the edge of the large face gradually inclines downward and forms the inclined plane or the circular-arc surface.

[0016] As a preferred technical solution of the present application, the pole piece is a negative pole piece.

[0017] The second technical solution adopted by the present application to solve the problem is:

[0018] A battery comprises a separator and at least two electrode structures as described above, the electrode structures being positive electrode structures or negative electrode structures, and the separator is arranged between the positive electrode structures and the negative electrode structures.

[0019] In summary, the electrode structure and the battery provided by the application have the following technical effects:

[0020] 1) The electrode structure of the application can prevent the edge of the tail end of the electrode from forming a sharp corner by arranging a puncture-preventing part at the connection between the large face and the end face, thereby avoiding the puncture of the separator by the edge of the tail end of the electrode when the battery is assembled, or the puncture of the separator by the sharp edge corner due to the expansion of the electrode during use.

[0021] 2) The battery of the application has an electrode structure with a smooth edge and is less likely to have a sharp puncture point, thereby avoiding the puncture of the separator by the edge of the tail end of the electrode when the battery is assembled, or the puncture of the separator by the sharp edge corner due to the expansion of the electrode during use. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 FIG. 1 is a structural schematic diagram of an electrode structure of an embodiment of the application;

[0023] Figure 2 FIG. 2 is a structural schematic diagram of one arrangement of a protective layer in Embodiment One of the application;

[0024] Figure 3 FIG. 3 is a structural schematic diagram of another arrangement of a protective layer in Embodiment One of the application;

[0025] Figure 4 FIG. 4 is a structural schematic diagram of the puncture-preventing part being a bevel in Embodiment Two of the application;

[0026] Figure 5 FIG. 5 is a structural schematic diagram of the puncture-preventing part being a circular arc surface in Embodiment Two of the application.

[0027] In the drawings, the reference signs have the following meanings:

[0028] 1, current collector; 10, active material coating; 11, main body region; 12, thinned region; 13, bevel; 14, circular arc surface; 15, protective layer; 151, first protective section; 152, second protective section; 153, third protective section; 16, large face; 161, first large face; 162, second large face; 17, end face; 18, right-angle connection region. DETAILED DESCRIPTION

[0029] In order to better understand and implement, the technical solutions in the embodiments of the application will be clearly and completely described below in combination with the drawings in the embodiments of the application.

[0030] In the description of the present application, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the specification of the present application is only for the purpose of describing specific embodiments and is not intended to limit the present application.

[0032] Referring to Figure 3 and Figure 4 , the present application discloses a pole piece structure, which comprises a pole piece, specifically, the pole piece has two large faces 16 and an end face 17, the two large faces 16 are oppositely arranged, and the end face 17 connects the two large faces 16. Among them, the connection part of the end face 17 and the large face 16 is provided with a puncture prevention part to make flexible contact with the diaphragm or other pole pieces.

[0033] On the basis of this structure, when using the pole piece structure of the present application, the processing step of the puncture prevention part can be added at the connection part of the end face 17 and the large face 16 of the pole piece during the manufacturing process of the pole piece, which can be realized by changing the thickness, shape of the material in this area or adding an additional protective layer.

[0034] When assembling the battery, a plurality of positive pole pieces, a plurality of negative pole pieces can be respectively inserted into the "Z"-shaped folded diaphragm to obtain a stacked battery, or the positive pole piece, the diaphragm and the negative pole piece can be stacked and wound for several turns to form a wound battery.

[0035] Among them, in order to ensure the neatness between the positive pole piece, the diaphragm and the negative pole piece, a certain tension is usually applied to the diaphragm during winding or stacking. However, this tension may cause the diaphragm to be elongated in the running direction, so that after the process is completed, the diaphragm has a large shrinkage in the running direction, which causes the diaphragm to be severely pressed against the pole piece. Especially in the winding process, since the diaphragm needs to be wound into a cylindrical or elliptical cylindrical shape together with the pole piece, the tension it receives is more complex, which may cause more obvious shrinkage. At this time, if there is a sharp right-angle area at the edge of the pole piece, the diaphragm is very easy to be punctured by the right-angle area when it is pressed against the pole piece.

[0036] The pole piece of the application can realize flexible contact with the diaphragm or other pole pieces through the anti-piercing part. Specifically, when the pole piece contacts or is pressed by the diaphragm or other pole pieces, the contact part is not easily affected by excessive stress due to the structure and shape of the anti-piercing part, thereby reducing the risk of piercing.

[0037] Therefore, the setting of the anti-piercing part can prevent the formation of a sharp right-angle area at the end of the pole piece, and further prevent the edge of the pole piece from piercing the diaphragm when the diaphragm shrinks. In addition, in the normal charging and discharging cycle of the battery, the negative pole piece will experience volume expansion and contraction. The anti-piercing part can increase the passivation degree of the edge of the pole piece, significantly reduce the sharpness of the edge of the pole piece, and maintain the smoothness of the edge, thereby avoiding the risk of piercing the isolation film under the conditions of vibration, pressure change, etc.

[0038] Embodiment one

[0039] This embodiment prevents the pole piece from piercing the diaphragm by adding an additional protective layer 15 to the pole piece.

[0040] Specifically, referring to Figure 1 , the end face 17 of the pole piece is connected to the large face 16 at a right angle and forms a right-angle connection area 18, referring to Figure 2 and Figure 3 , the right-angle connection area 18 is provided with a protective layer 15, and the protective layer 15 extends from the large face 16 to the end face 17. The protective layer 15 forms the anti-piercing part.

[0041] Specifically, in the manufacturing process of the pole piece, the pole piece is usually prepared by cutting a large piece of positive or negative material into small pieces of a specific shape and size. In the cutting process, in order to ensure the size accuracy and edge neatness of the pole piece, a sharp knife is usually used for cutting, which can cause the edge of the pole piece at the end to form a right-angle connection area.

[0042] On the right-angle connection area 18, a protective layer 15 can be applied by a specific process (such as spraying, plating, or attaching), which uniformly covers the entire right-angle connection area 18 and smoothly extends from the large face 16 to the end face 17.

[0043] Therefore, by setting the protective layer 15 as the anti-piercing part on the right-angle connection area 18, the pole piece can be prevented from piercing the diaphragm during the stacking or winding process, or due to the expansion of the pole piece material during use. At the same time, the presence of the protective layer 15 makes the battery more stable when subjected to external impact or vibration, which can to some extent reduce the damage of these external factors to the internal structure of the battery and maintain the normal working state of the battery.

[0044] As a preferred technical solution of the application, referring to Figure 2Two large faces 16 are respectively a first large face 161 and a second large face 162, and the first large face 161 and the second large face 162 form a first right-angle connecting area and a second right-angle connecting area with the end face 17 respectively, wherein the first right-angle connecting area and the second right-angle connecting area are provided with the protective layer 15.

[0045] It should be noted that the pole piece has two end faces 17, which are respectively arranged at two ends of the large face 16 in the length direction, and the first large face 161 and the two end faces 17 form two first right-angle connecting areas, and the second large face 162 and the two end faces 17 form two second right-angle connecting areas. In addition, the pole piece also has two side faces, which are respectively arranged at two sides of the large face 16 in the width direction, and the pole piece as a whole has a cuboid shape.

[0046] In the manufacturing process of the pole piece, the right-angle connecting areas 18 formed by the large face 16 and the end face 17 are located at the two ends of the pole piece. Since the pole piece is in contact with the diaphragm through the large face 16, and the diaphragm is more extruded at the end of the pole piece when it is contracted, the protective layer 15 is arranged on the right-angle connecting areas 18 at the two ends, which can form comprehensive coverage, so that the edges of the entire pole piece are effectively protected.

[0047] That is, the embodiment sets the protective layer 15 at the four right-angle connecting areas 18 of the pole piece. In the normal use process of the battery, the pole piece will undergo repeated charge and discharge cycles, resulting in expansion and contraction of the volume. However, due to the presence of the protective layer 15, even if the edges of the pole piece become slightly sharp due to expansion, the diaphragm will not be easily pierced.

[0048] In addition, the protective layer 15 can also play a certain buffering role, reducing the impact on the diaphragm due to vibration or internal pressure changes, and ensuring the stable operation of the battery.

[0049] As a preferred technical solution of the present application, referring to Figure 3 The protective layer 15 includes a first protective segment 151, a second protective segment 152, and a third protective segment 153. Specifically, the first protective segment 151 covers the edge of the first large face 161, the second protective segment 152 covers the end face 17, the third protective segment 153 covers the edge of the second large face 162, and the second protective segment 152 connects the first protective segment 151 and the third protective segment 153.

[0050] The first protective section 151 covers the edge of the first large surface 161 of the tab, and is used to protect the first right-angle connection area at the intersection of the first large surface 161 and the end surface 17, preventing the area from being punctured by sharp edges during battery assembly and use. The third protective section 153 covers the edge of the second large surface 162 of the tab, and has a similar function to the first protective section 151, i.e. to protect the second right-angle connection area at the intersection of the second large surface 162 and the end surface 17, ensuring the safety of the area during battery operation. The second protective section 152 connects the first protective section 151 and the third protective section 153, i.e. in this embodiment, a protective layer 15 is provided at both ends of the tab, and the protective layer 15 covers the two right-angle connection areas 18 at one end.

[0051] Thus, the right-angle connection areas 18 at the same end are covered by a continuous and smooth protective layer 15, effectively protecting the edges of the entire tab, and the smooth protective layer 15 helps to reduce stress concentration within the protective layer 15, improving the overall stability and durability of the protective layer 15.

[0052] In addition, the presence of the protective layer 15 increases the structural strength of the edges of the tab at both ends. During battery charging and discharging, the negative electrode material will undergo volume expansion and contraction, which can cause cracks or damage to the edges of the tab. The protective layer 15 can absorb these stresses, reducing the occurrence of cracks and improving the overall structural strength of the tab.

[0053] As a preferred technical solution of the present application, referring to Figure 2 and Figure 3 the protective layer 15 is an insulating adhesive paper, and the thickness of the insulating adhesive paper is H, the value of H is in the range of 20-60 μm, and the width of the insulating adhesive paper along the length direction of the large surface 16 is W, the value of W is in the range of 5-15 mm.

[0054] Based on this structure, during use, a certain area of insulating adhesive paper can be fixed on the edge of the tab through simple cutting, pasting and other processes, without the need for complex manufacturing equipment and process flow. This helps to reduce the manufacturing cost of the battery and improve production efficiency.

[0055] The protective layer 15 is an insulating adhesive paper, which is a common insulating material and has the characteristics of easy processing and installation, and can provide insulation protection. Within the battery, a certain insulation distance needs to be maintained between the negative tab and the positive tab to prevent short circuit. The insulating adhesive paper can effectively isolate the edges of the positive and negative tabs, preventing direct contact between them, thereby significantly reducing the risk of short circuit.

[0056] Meanwhile, the thickness H and the width W of the insulating adhesive paper are set within a certain range, which can guarantee the protection effect while optimizing the performance and cost of the battery. Specifically, if the thickness H of the insulating adhesive paper is less than 20 pm, the thinner insulating adhesive paper can not provide sufficient electrical isolation, and when subjected to external forces, such as pulling, bending or extrusion, it is more likely to be damaged or torn, so that the sharp corners of the edge of the pole piece are exposed. If the thickness H of the insulating adhesive paper is greater than 60 pm, the thicker insulating adhesive paper can provide better insulation and protection effect, but it will also increase the weight and volume of the battery, and reduce the energy density.

[0057] Therefore, the thickness H of the insulating adhesive paper is set to be between 20-60 pm, so that it can prevent the sharp corners of the edge of the pole piece from piercing the diaphragm, and at the same time has a good insulation protection effect, and will not increase the weight and volume of the battery.

[0058] Similarly, if the width W of the insulating adhesive paper is less than 5 mm, the narrower insulating adhesive paper can not completely cover the edge of the pole piece, or the connection strength of the insulating adhesive paper and the large surface 16 is weak, and cannot provide sufficient protection. If the width W of the insulating adhesive paper is greater than 15 mm, although it can provide more comprehensive protection coverage, it will also increase the weight and volume of the battery. Therefore, the width W of the insulating adhesive paper is set to be between 5-15 mm, which can achieve a good balance between performance and cost on the premise of ensuring the safety of the battery.

[0059] In addition, the protective layer 15 can also be a ceramic coating, which can act as a barrier to effectively block the direct impact of the edge of the pole piece under extreme conditions and prevent the diaphragm from being pierced.

[0060] Embodiment Two

[0061] Different from embodiment one, the present embodiment forms a puncture-proof part by changing the material thickness and shape of the edge of the tail end of the pole piece, thereby preventing the diaphragm from being pierced.

[0062] Referring to Figure 4 , the end surface 17 is connected with the large surface 16 through a bevel 13, and the two ends of the bevel 13 form an obtuse angle connection area with the end surface 17 and the large surface 16 respectively. Among them, the obtuse angle connection area forms the puncture-proof part.

[0063] Specifically, during the manufacturing process of the pole piece, the positive electrode material or the negative electrode material can be processed into a shape with a bevel 13 connection and an obtuse angle connection area through a precise machining process, such as stamping, cutting or laser processing, etc. During the assembly process of the battery, the pole piece with the bevel 13 connection and the obtuse angle connection area is inserted into the battery structure.

[0064] The angle between the inclined surface 13 and the end surface 17 and the large surface 16 is an obtuse angle, that is, the angle is greater than 90°. Due to the existence of the obtuse angle connection area, the edge of the pole piece becomes smoother, which can effectively reduce the generation of sharp edges, thereby reducing the risk of piercing when the pole piece directly contacts the adjacent components (such as the diaphragm).

[0065] In addition, the setting of the inclined surface 13 and the obtuse angle connection area enhances the overall structural strength of the pole piece, so that the pole piece can better disperse stress when subjected to external force, reducing the occurrence of cracks and damage.

[0066] As a preferred technical solution of the present application, referring to Figure 5 , the end surface 17 and the large surface 16 are connected by a circular arc surface 14, and the circular arc surface 14 forms the anti-piercing part.

[0067] Specifically, during the manufacturing process of the pole piece, the end surface 17 and the large surface 16 can be smoothly transitioned by cutting or laser processing, etc., to form a circular arc surface 14 connection. During the battery assembly process, the pole piece with the circular arc surface 14 connection is inserted into the battery structure.

[0068] Due to the existence of the circular arc surface 14, the transition between the end surface 17 and the large surface 16 is smooth and continuous, without sharp corners or abrupt changes, significantly reducing the risk of piercing when the pole piece directly contacts the diaphragm.

[0069] In addition, the circular arc surface 14 also helps to form a more uniform pressure distribution inside the battery, reducing the generation of pole piece edge damage or cracks due to volume changes.

[0070] As a preferred technical solution of the present application, referring to Figures 1 to 5 , the pole piece includes a current collector 1 and an active material coating 10, specifically, the active material coating 10 is arranged on both sides of the current collector 1, and the large surface 16 is located on the side of the active material coating 10 away from the current collector 1.

[0071] The active material coating 10 includes a main body area 11 and a thinning area 12, the main body area 11 is located in the middle of the current collector 1, and the thinning area 12 is located at the edge of the current collector 1. The thickness of the thinning area 12 gradually decreases from the side close to the main body area 11 to the side away from the main body area 11, so that the edge of the large surface 16 gradually inclines downward and forms an inclined surface 13 or a circular arc surface 14.

[0072] On the basis of this structure, during the manufacturing process of the pole piece, the active material is first coated on both sides of the current collector 1 to form the active material coating 10. Then the regions at both ends of the active material coating 10 can be thinned by laser etching processing, thereby forming the thinning area 12. The formation of the inclined surface 13 and the circular arc surface 14 can be formed by changing the movement trajectory of the laser galvanometer in the laser etching equipment.

[0073] Thus, by forming the thickness-reduced region 12, the edge of the large surface 16 can be formed into a bevel 13 or a rounded surface 14, and the large surface 16 can be smoothly connected to the end surface 17, thereby significantly reducing the risk of the edge of the pole piece piercing the separator. Even under extreme conditions, the bevel 13 or the rounded surface 14 can effectively prevent the generation of a sharp edge, thereby protecting the integrity of the internal structure of the battery.

[0074] In addition, the thickness-reduced region 12 is located at the edge of the current collector 1, which reduces the active material mass of the edge portion, thereby reducing the influence of the edge effect on the performance of the battery. Moreover, the formation of the bevel 13 or the rounded surface 14 can also reduce the stress concentration phenomenon at the corner.

[0075] As a preferred technical solution of the present application, the pole piece is a negative pole piece.

[0076] When the negative electrode material is a silicon-based material, it is more likely to produce significant volume changes during charging and discharging. Such volume changes can cause the deformed right-angle region at the end of the negative pole piece to become more sharp, thereby increasing the risk of piercing the separator.

[0077] Therefore, by providing the anti-piercing part (such as the bevel 13, the rounded surface 14, or the thickness-reduced region 12) on the negative pole piece, the present application can prevent the generation of a sharp edge, thereby significantly reducing the risk of the negative pole piece piercing the separator during expansion.

[0078] Example Three

[0079] The present embodiment discloses a battery comprising a separator and at least two pole piece structures as in Example One or Example Two, and the pole piece is a positive pole piece or a negative pole piece, wherein the separator is arranged between the positive pole piece and the negative pole piece.

[0080] On the basis of this structure, when the pole pieces and the separator are assembled to form a stacked battery, a plurality of positive pole pieces and a plurality of negative pole pieces can be respectively inserted into the "Z"-shaped folded separator, and then the layers of the battery are fixed together by pressing or welding, thereby obtaining a stacked battery. When the pole pieces and the separator are assembled to form a wound battery, the positive pole piece, the separator, and the negative pole piece can be sequentially stacked, and then the stacked assembly is wound into a cylindrical or flat structure, thereby obtaining a wound battery.

[0081] The separator can isolate the positive and negative electrode materials to prevent short circuiting and allow electrolyte ions to pass through to complete the charging and discharging process. In order to protect the separator from being pierced, the present application provides an anti-piercing part at the connection between the large surface 16 and the end surface 17 of the pole piece, so that the originally sharp edge at the end of the pole piece becomes smooth and is less likely to produce a sharp piercing point. Therefore, during the assembly and use of the battery, the risk of the edge of the pole piece piercing the separator can be significantly reduced, thereby improving the safety performance of the battery.

[0082] The specific structure and forming method of the puncture-proof part are described in detail in Embodiment One and Embodiment Two, and will not be described again here.

[0083] The technical means disclosed in the application scheme is not limited to the technical means disclosed in the above embodiments, but also includes the technical solutions composed of any combination of the above technical features. It should be noted that, for ordinary skilled persons in the art, without departing from the principles of the application, some improvements and refinements can also be made, which are also considered within the protection scope of the application.

Claims

1. A pole piece structure, characterized by: The pole piece has two large faces arranged oppositely and an end face connecting the two large faces, and the end face is provided with a puncture-proof part at the connection with the large face to make flexible contact with a diaphragm or other pole piece; the pole piece structure further comprises a protective layer extending from the large face to the end face, the protective layer is formed as the puncture-proof part, the protective layer is insulating adhesive paper, the thickness of the insulating adhesive paper is H, the value range of H is 20-60μm, and the width of the insulating adhesive paper along the length direction of the large face is W, the value range of W is 5-15mm.

2. The pole piece structure of claim 1, wherein: The end face and the large face are connected at a right angle and form a right-angle connection area, and the right-angle connection area is provided with the protective layer.

3. The pole piece structure of claim 2, wherein: The two large faces are a first large face and a second large face respectively, and the first large face and the second large face form a first right-angle connection area and a second right-angle connection area with the end face respectively, and the first right-angle connection area and the second right-angle connection area are both provided with the protective layer.

4. The pole piece structure of claim 3, wherein: The protective layer comprises a first protective segment, a second protective segment and a third protective segment, the first protective segment covers the edge of the first large face, the second protective segment covers the end face, and the third protective segment covers the edge of the second large face, and the second protective segment connects the first protective segment and the third protective segment.

5. The pole piece structure of claim 1, wherein: The end face and the large face are connected at an inclined plane, and the two ends of the inclined plane form an obtuse-angle connection area with the end face and the large face respectively; the obtuse-angle connection area is formed as the puncture-proof part.

6. The pole piece structure of claim 1, wherein: The end face and the large face are connected at a circular-arc surface, and the circular-arc surface is formed as the puncture-proof part.

7. The pole piece structure of claim 5 or 6, characterized in that: The pole piece comprises a current collector and an active material coating, and the active material coating is arranged on both sides of the current collector; the large face is located on the side of the active material coating away from the current collector; the active material coating comprises a main body area and a thinning area, the main body area is located in the middle of the current collector, and the thinning area is located at the edge of the current collector; the thickness of the thinning area gradually decreases from the side close to the main body area to the side away from the main body area, so that the edge of the large face gradually inclines downward and forms an inclined plane or a circular-arc surface.

8. The pole piece structure of claim 1, wherein: The pole piece is a negative pole piece.

9. A battery, characterized by: The battery comprises a diaphragm and at least two pole piece structures as claimed in any one of claims 1-8, the pole piece is a positive pole piece or a negative pole piece, and the diaphragm is arranged between the positive pole piece and the negative pole piece.

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