Battery cover plate structure

Abstract

A battery cover plate structure, comprising an inner anti-explosion groove (1). The inner anti-explosion groove (1) is located on the reverse side of a cover plate and is annularly distributed; a plurality of inner liquid injection holes (3) distributed in the circumferential direction of the cover plate are formed on the reverse side of the cover plate; an outer anti-explosion groove (2) is formed on the reverse side of the inner anti-explosion groove (1); the outer anti-explosion groove (2) is annularly distributed; an anti-explosion scored line (5) is arranged in the center of the outer anti-explosion groove (2); a plurality of outer liquid injection holes (4) distributed in the circumferential direction of the cover plate are formed in the front surface of the cover plate; and the inner liquid injection holes (3) are in one-to-one correspondence with the outer liquid injection holes (4). The anti-explosion grooves are formed on both the front and reverse sides of the cover plate so as to effectively protect the anti-explosion scored line (5), thereby avoiding damage to the anti-explosion scored line (5) caused by an external force during processing, transportation or use of the cover plate or battery.

Description

A battery cover structure Technical Field

[0001] The present invention relates to the field of battery cover plates, and in particular to a battery cover plate structure with optimized explosion-proof engraved lines and liquid injection holes. Background Art

[0002] The explosion-proof scoreline mentioned in the present invention is a structural design commonly used on cylindrical lithium battery covers. Generally, the cross-section of the explosion-proof scoreline is V-shaped. Its main function is that when the internal pressure of the battery cell increases, the position corresponding to the scoreline is subjected to the largest relative pressure relative to the entire cover plane, and is most likely to deform and then rupture, thereby achieving the purpose of directional pressure relief, thereby avoiding a sharp rise in the internal pressure of the battery cell, which may cause a radial explosion or thermal runaway of the entire battery cell. In the published Chinese patent document "CN218996893U---New Battery Cover Structure and Cylindrical Lithium Battery", it is mentioned that by setting an explosion-proof scoreline, pressure relief is performed when the internal pressure of the battery is too high, thereby preventing the entire cover from flying out. In the published Chinese patent document "CN218731353U---A Battery Cover and Cylindrical Battery", it is mentioned that an inner cover and an outer cover are designed, and an explosion-proof scoreline is provided on the inner cover. The main benefit of this patent is that the inner cover with a notched structure can not only ensure that after the electrolyte is injected, the shell is welded to seal the interior of the battery, but also ensure that the inner cover can be broken open when the internal pressure exceeds a certain value, so that the pressure inside the shell can be released, that is, to avoid thermal runaway of the battery. Although the concept of explosion-proof scoring lines is mentioned, its specific structure is not disclosed. The existing technical solution can be summarized as only solving the problem of timely pressure relief when the internal pressure of the battery is too high by setting explosion-proof scoring lines, but it does not deeply optimize the design of the explosion-proof scoring lines to solve the stability problems of the explosion-proof scoring lines and the problem of timely valve opening of the explosion-proof scoring lines. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems of poor stability of explosion-proof engraved lines and unstable and unreasonable design of battery cover plates in the prior art, and to provide a battery cover plate structure with the advantages of ensuring the stability of explosion-proof engraved lines, ensuring battery sealing, and preventing battery leakage.

[0004] The technical solution adopted by the present invention to solve the above-mentioned technical problems is a battery cover structure, including an inner explosion-proof groove, the inner explosion-proof groove is located on the back of the cover and is distributed in an annular shape, the back of the cover is provided with a number of inner liquid injection holes distributed along the circumference of the cover, the back of the inner explosion-proof groove is provided with an outer explosion-proof groove, the outer explosion-proof groove is distributed in an annular shape, the center of the outer explosion-proof groove is provided with an explosion-proof marking line, the front of the cover is provided with a number of outer liquid injection holes distributed along the circumference of the cover, and the inner liquid injection holes and the outer liquid injection holes correspond one to one. The front and back of the cover are provided with explosion-proof grooves, and the center of the outer explosion-proof groove is provided with explosion-proof marking lines. Explosion-proof grooves are provided on both the front and back, which can effectively protect the explosion-proof marking lines and prevent the explosion-proof marking lines from being damaged by external forces encountered during the processing, transportation or use of the cover or battery. The depth of the explosion-proof engraved line is set to 1 / 5~2 / 3 of the thickness of the explosion-proof groove, which can be adjusted according to the actual design needs of the battery cell. The explosion-proof engraved line can avoid the cracks caused by the original V-shaped sharp corners during the processing of the explosion-proof engraved line, thereby improving the processing stability of the explosion-proof engraved line.

[0005] Preferably, the depth of the explosion-proof line is less than the thickness of the outer explosion-proof groove, the cross-section of the explosion-proof line is an open U-shape, the opening angle of the cross-section of the explosion-proof line is greater than or equal to 10 degrees and less than or equal to 60 degrees, and the bottom end of the cross-section of the explosion-proof line is curved. The U-shaped design of the explosion-proof line can avoid cracks caused by the original V-shaped sharp corners during the processing of the explosion-proof line, thereby improving the processing stability of the explosion-proof line.

[0006] Preferably, a welding groove is provided on the front of the cover plate. The welding groove is annular, closer to the center of the cover plate than the external explosion-proof groove, and the external liquid injection hole is closer to the center of the cover plate than the welding groove. The opening of the welding groove faces the front of the cover plate, and the depth of the welding groove is less than the thickness of the cover plate. The welding groove can be set to a circular, semicircular or segmented arc shape. The main function of the welding groove is to perform external laser penetration welding on the cover plate after assembly. The main purpose of penetration welding is to weld the cover plate body to the current collecting plate inside the battery cell to achieve the function of electrical connection. The penetration welding method can be point-shaped, continuous linear or other shapes. After welding, the external molten part should not exceed the outer plane of the cover plate body.

[0007] Preferably, the inner liquid injection hole is closer to the center of the cover plate than the inner explosion-proof groove, the diameter of the inner liquid injection hole is larger than the diameter of the outer liquid injection hole, the outer liquid injection hole is inscribed in the inner liquid injection hole, the inner liquid injection hole and the outer liquid injection hole form a through hole as a whole, and the sum of the thickness of the inner liquid injection hole and the thickness of the outer liquid injection hole is equal to the thickness of the cover plate. The inner liquid injection hole is opened on the back of the cover plate, and the outer liquid injection hole is on the front of the cover plate. The diameter of the inner liquid injection hole needs to be larger than the diameter of the outer liquid injection hole. The relative positions of the inner and outer liquid injection holes, the area of ​​the outer liquid injection hole needs to cover the area of ​​the entire inner liquid injection hole. The number of inner and outer liquid injection holes can be set according to design requirements. The inner and outer liquid injection holes form a through hole as a whole, and the sum of the thickness of the inner and outer liquid injection holes is equal to the thickness of the cover plate body. Used for liquid injection work.

[0008] Preferably, the front of the cover plate is provided with an injection hole boss, the injection hole boss is closer to the center of the cover plate than the welding groove, the external injection hole is closer to the center of the cover plate than the injection hole boss, the injection hole boss is annular as a whole, the cross-sectional shape of the injection hole boss is a right-angled trapezoid, the hypotenuse of the right-angled trapezoid is located on the side close to the external injection hole, and a gap is left between the injection hole boss and the external injection hole. The advantage of the injection hole boss design is that it can effectively avoid the reverse sputtering of the electrolyte to the surrounding of the injection hole as the electrolyte is injected or the injection speed increases during injection, affecting the final sealing welding effect and yield of the battery cell. Electrolyte is easily retained at the inner edge of the injection hole. The presence of electrolyte will cause the entire sealing welding to fail, or cause pores to appear at the welding position, resulting in the risk of leakage during the subsequent use of the battery cell.

[0009] Preferably, a central welding groove is defined in the center of the front face of the cover plate. The depth of the central welding groove is the same as the depth of the welding groove, and the external injection port is located outside the central welding groove. The primary purpose of the central welding groove is to perform penetration welding, connecting the cover plate body to the corresponding collector plate within the telecommunications system. The penetration welding pattern can be point-like, continuous, or in other shapes.

[0010] Preferably, an external liquid injection hole circle is provided on the front side of the cover plate, the external liquid injection hole is inscribed in the external liquid injection hole circle, the central welding groove is concentric with the external liquid injection hole circle, and the diameter of the central welding groove is smaller than the diameter of the external liquid injection hole circle.

[0011] Preferably, the cover plate is disc-shaped as a whole, with an annular edge groove provided on the back edge of the cover plate. The edge groove is further away from the center of the cover plate than the inner explosion-proof groove. In order to match the cylindrical battery housing, a groove is provided on the edge of the back edge of the cover plate body to match the subsequent welding between the housings.

[0012] Preferably, the annular inner wall of the injection hole boss forms a truncated cone structure, which is equipped with a sealing pin. The edge shape of the sealing pin matches the edge shape of the truncated cone structure, and the thickness of the sealing pin is less than the height of the injection hole boss. Increasing the sealing pin's coordination improves the injection hole welding yield, further ensures the sealing of the battery cell, and avoids the risk of leakage caused by welding around the injection hole.

[0013] The present invention has the advantage of a simple integrated cover structure, comprising only two metal parts: the cover body and the sealing pin, rather than a composite component. The cover body is easy to manufacture and can be integrally formed by stamping, thereby improving assembly efficiency and reducing production costs.

[0014] Another beneficial effect of the present invention is that the design of the welding groove greatly increases the welding area between the cover body and the current collecting plate, thereby improving the battery cell's ability to handle high-rate currents and increasing the battery's power input and output.

[0015] Another beneficial effect of the present invention is that the design of the internal and external injection holes and the injection hole bosses proposed in the present invention will greatly improve the final sealing welding effect and yield of the battery cell. It avoids the formation of holes or sealing defects in the sealing weld caused by residual electrolyte, thereby reducing the risk of leakage during subsequent use of the battery.

[0016] Another beneficial effect of the present invention is that the double-sided explosion-proof groove design fully protects the stability of the explosion-proof engraved line, effectively preventing the cover plate or battery from being damaged by external forces encountered during processing, transportation or use.

[0017] Another beneficial effect of the present invention is that the "U"-shaped explosion-proof engraved line can avoid the occurrence of cracks caused by the original V-shaped sharp corners during the processing of the explosion-proof engraved line, thereby improving the processing stability of the explosion-proof engraved line. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG1 is a schematic cross-sectional view of a battery cover according to the present invention.

[0019] FIG2 is a schematic top view of the front side of the battery cover of the present invention.

[0020] FIG3 is a schematic top view of the reverse side of the battery cover of the present invention.

[0021] FIG4 is an enlarged schematic diagram of point A in FIG1 .

[0022] FIG5 is a schematic cross-sectional view of the explosion-proof score line of the present invention.

[0023] FIG6 is a schematic top view of the sealing nail of the present invention.

[0024] FIG7 is a schematic cross-sectional view of the sealing nail of the present invention.

[0025] In the figure: 1. Inner explosion-proof groove, 2. Outer explosion-proof groove, 3. Inner liquid injection hole, 4. Outer liquid injection hole, 5. Explosion-proof engraved line, 6. Welding groove, 7. Liquid injection hole boss, 8. Outer liquid injection hole circle, 9. Central welding groove, 10. Edge groove, 11. Cone structure, 12. Sealing pin, A. Magnification symbol, θ. Angle symbol, R. Radius symbol. DETAILED DESCRIPTION

[0026] The specific implementation of the technical solution of the present invention will be further described below through examples and in conjunction with the accompanying drawings.

[0027] Example 1

[0028] As shown in Figures 1 to 7, the present invention discloses a battery cover structure. In this embodiment, it is specifically applied to cylindrical batteries. As a cover for cylindrical batteries, it includes an inner explosion-proof groove 1. The inner explosion-proof groove 1 is provided on the reverse side of the cover. The inner explosion-proof groove 1 is annular as a whole. The reverse side of the cover is provided with a number of inner liquid injection holes 3 distributed along the circumference of the cover. In this embodiment, four inner liquid injection holes 3 are provided. The reverse side of the inner explosion-proof groove 1 is provided with an outer explosion-proof groove 2. The outer explosion-proof groove 2 is also annularly distributed. The outer explosion-proof groove 2 and the inner explosion-proof groove 1 are in a positive and negative relationship corresponding to each other. An explosion-proof mark 5 is provided at the center of the outer explosion-proof groove 2. The front side of the cover is provided with a number of outer liquid injection holes 4 distributed along the circumference of the cover. In this embodiment, four outer liquid injection holes 3 are provided. The inner liquid injection holes 3 and the outer liquid injection holes 4 correspond one to one. It should be noted that the battery cover disclosed in the present invention is covered on a cylindrical lithium battery. The cover is divided into a front and a back with reference to the battery cell in the lithium battery. The side facing the battery cells in the lithium battery is the back side of the cover plate, and the side away from the battery cells in the lithium battery is the front side of the cover plate. This definition is because the cover plate is covered on the cylindrical lithium battery, and what can be seen from a human perspective is recorded as the front side of the cover plate, that is, the back side of the cover plate facing the battery cells. Figure 1 is a cross-sectional schematic diagram of the cover plate, the upper half of the cross-sectional diagram of Figure 1 is the back side of the cover plate, that is, the side of the cover plate facing the battery cells, the lower half of the cross-sectional diagram of Figure 1 is the front side of the cover plate, that is, the back side of the cover plate facing the battery cells, and Figure 2 is a top view schematic diagram of the front side of the cover plate, and Figure 3 is a top view schematic diagram of the back side of the cover plate. The outermost circle of the back side of the cover plate is provided with an edge groove 10, and the edge groove 10 is annular, forming a ring layer on the outermost circle of the back side of the cover plate. This design is to match the shell of the cylindrical battery, and a groove is provided on the edge of the back side of the cover plate body to match the subsequent welding between the shells. In addition to the edge groove 10, the back of the cover is also provided with an inner explosion-proof groove 1 at a position closer to the center of the cover, and the inner liquid injection hole 3 is closer to the center of the cover than the inner explosion-proof groove 1. Taking the back of the cover as an example, it can be understood that the inner explosion-proof groove 1 is in the outer circle, the inner liquid injection hole 3 is in the inner circle, and the edge groove 10 is in the outermost circle. From the front of the cover, the outer explosion-proof groove 2 is in the outermost circle. For the convenience of subsequent description, this circle is recorded as the first circle. The explosion-proof engraved line 5 is set at the center of the outer explosion-proof groove 2. The welding groove 6 is closer to the center of the cover than the outer explosion-proof groove 2 and is recorded as the second circle. The injection hole boss 7 is closer to the center of the cover than the welding groove 6 and is recorded as the third circle. The outer injection hole circle 8 is closer to the center of the cover than the injection hole boss 7 and is recorded as the fourth circle. The central welding groove 9 is located in the center of the cover and is recorded as the fifth circle. From Figure 2, the outer injection hole 4 is considered to be in the center of the fourth and fifth circles. The outer injection hole 4 is inscribed in the outer injection hole circle 8, and a gap is left between the outer injection hole 4 and the central welding groove 9. Providing explosion-proof grooves on both the front and back of the cover can effectively protect the explosion-proof engraved line 5 and prevent the cover or battery from being damaged by external forces encountered during processing, transportation or use.The width of the explosion-proof groove can be adjusted according to actual needs. In this embodiment, the width of the outer explosion-proof groove 2 and the inner explosion-proof groove 1 is set to 2 mm. The annular distribution means that the outer explosion-proof groove 2 and the inner explosion-proof groove 1 form a ring on the battery cover when viewed from above. In this embodiment, the thickness of the cover body is set to 1.0 mm. In actual use, the cover diameter can be selected from other common sizes such as 18 mm, 21 mm, 26 mm, 32 mm, 46 mm, and 60 mm. In this example, the size selected is 18 mm. The cover is generally disc-shaped, with an annular edge groove 10 on the edge of the back of the cover. The edge groove 10 is further away from the center of the cover than the inner explosion-proof groove 1. The cover body is characterized by being made of commonly used metal materials, including steel, aluminum, copper, etc.

[0029] From the cross-sectional view of Figure 1, it can be seen that the front of the cover plate is provided with a liquid injection hole boss 7. The liquid injection hole boss 7 is closer to the center of the cover plate than the welding groove 6, and the external liquid injection hole 4 is closer to the center of the cover plate than the liquid injection hole boss 7. The liquid injection hole boss 7 is annular as a whole, and the cross-sectional shape of the liquid injection hole boss 7 is a right-angled trapezoid. The hypotenuse of the right-angled trapezoid is located on the side close to the external liquid injection hole 4, and a gap is left between the liquid injection hole boss 7 and the external liquid injection hole 4. The liquid injection hole boss 7 is on the front of the cover plate, and the liquid injection hole boss 7 is formed by pulling along the edge of the external liquid injection hole 4 away from the battery cell. Generally speaking, the liquid injection hole boss 7 can have any geometric shape according to actual production needs. In the embodiment of the present invention, the liquid injection hole boss 7 is annular. The annular inner wall of the injection hole boss 7 forms a truncated cone structure 11, which is provided with a sealing pin 12 that matches it. The edge shape of the sealing pin 12 matches the edge shape of the truncated cone structure 11, and the thickness of the sealing pin 12 is less than the height of the injection hole boss 7.

[0030] As shown in Figure 7 and Figure 1, it can be seen that the edge of the truncated cone structure 11 is a tapered surface. From the cross-sectional view, the entire truncated cone structure 11 is an isosceles trapezoid. The edge of the corresponding sealing nail 12 also presents a tapered design, and the tapered angles of the tapered surface and the tapered design are consistent. The angle of the cone here refers to the angle with the vertical direction. The diameter of the tapered surface of the truncated cone structure 11 gradually decreases from the outside to the inside. The outside here refers to the side away from the cover plate, and the inside here refers to the side close to the cover plate. The diameter of the tapered surface here refers to the diameter of the truncated cone structure 11. The angle of the cone can be set between 5 degrees and 30 degrees. In this embodiment, it is set to 30 degrees. The thickness of the sealing nail 12 is less than the height of the injection hole boss 7. The design advantage of the injection hole boss 7 is that it can effectively avoid the electrolyte from being reversely sputtered to the surrounding area of ​​the injection hole as the electrolyte is injected or the injection speed increases during injection, affecting the final sealing welding effect and yield of the battery cell. Electrolyte is likely to remain at the inner edge of the injection hole. The presence of electrolyte will cause the entire sealing welding to fail, or cause pores to appear at the welding position, which will create the risk of leakage during the subsequent use of the battery cell. In this embodiment, the diameter of the inner injection hole 3 is 3 mm, and the diameter of the outer injection hole 4 is 2 mm. The number of inner injection holes 3 and outer injection holes 4 is 4, which are evenly distributed along the circumference of the cover plate. The inner injection hole 3 and the outer injection hole 4 are tangent to each other in the direction of the center of the cover plate. It can be seen from Figure 1 that the outer injection hole 4 and the side of the inner injection hole 3 close to the center of the cover plate are on the same straight line, which is the tangent feature. The thickness of the inner injection hole 3 is equal to the thickness of the outer injection hole 4, and its thickness is 1 / 2 of the thickness of the cover plate. The thickness of the cover plate does not include the height of the injection hole boss 7. Figure 1 helps to understand that the thickness of the cover plate does not include the raised part of the injection hole boss 7. It is specially noted here that the diameter of the circle formed by the centers of the four external liquid injection holes 4 in this embodiment is 6 mm. This circle is not marked in the drawings of the specification only for the convenience of explaining the size of the central welding groove 9 later. The diameter of the central welding groove 9 is 4 mm, and the depth of the central welding groove 9 is the same as the depth of the welding groove 6. The external liquid injection hole 4 is located outside the central welding groove 9. The shape of the central groove 9 can be any geometric shape according to actual application. In this embodiment, it is a circle, and its area is smaller than the area of ​​the external liquid injection hole circle 8. The main purpose of the central welding groove 9 is to perform penetration welding here to weld the cover plate to the corresponding current collecting plate inside the battery cell. The penetration welding method can be point-shaped, continuous linear or other shapes. In this embodiment, the penetration welding method is point welding. An external liquid injection hole circle 8 is also provided on the front of the cover plate. The external liquid injection hole 4 is inscribed in the external liquid injection hole circle 8. The central welding groove 9 is concentric with the external liquid injection hole circle 8, and the diameter of the central welding groove 9 is smaller than the diameter of the external liquid injection hole circle 8.

[0031] The front of the cover plate of the present invention is also provided with a welding groove 6, which is annular. The welding groove 6 is closer to the center of the cover plate than the outer explosion-proof groove 2, and the outer liquid injection hole 4 is closer to the center of the cover plate than the welding groove 6. The opening of the welding groove 6 faces the front of the cover plate, and the depth of the welding groove 6 is less than the thickness of the cover plate. The welding groove 6 can be set to a circular, semicircular or segmented arc shape.

[0032] The specific characteristics of the welding groove 6 are that the opening of the welding groove 6 faces the front of the cover plate, and the depth of the welding groove 6 is between 1 / 3 and 2 / 3 of the thickness of the cover plate. In this embodiment, the depth of the welding groove 6 is set to 1 / 2 of the thickness of the cover plate. The welding groove 6 can be set to a circular, semicircular or segmented arc shape according to the actual application. The width of the welding groove 6 can be adjusted according to the actual application needs. In this embodiment, the width of the welding groove 6 is set to 2mm. The main function of the welding groove 6 is to perform external laser penetration welding after the assembly of the cover plate is completed. The main purpose of penetration welding is to weld the cover plate to the current collecting plate inside the battery cell to achieve the function of electrical connection. The penetration welding method can be point-shaped, continuous linear or other shapes. After welding, the external molten part should not exceed the outer plane of the cover plate body. In this embodiment, the penetration welding method is continuous linear.

[0033] As can be seen from Figures 4 and 5, the main feature of the explosion-proof score line of the present invention is that the depth of the explosion-proof score line 5 is set to between 1 / 5 and 2 / 3 of the thickness of the outer explosion-proof groove 2. In this embodiment, the depth of the explosion-proof score line 5 is 1 / 2 of the thickness of the outer explosion-proof groove. It can be adjusted according to the actual design needs of the battery cell. The cross-sectional shape of the explosion-proof score line 5 is an open "U" shape, and the opening angle θ is between 10 degrees and 6 degrees. The bottom end of the cross-sectional shape of the explosion-proof score line 5 is arc-shaped, and the arc radius R can be set to between 0.01 and 1. The θ and R values ​​can be adjusted accordingly according to the actual design needs. In this embodiment, the θ value is set to 30 degrees and the R value is set to 0.03. The U-shaped design of the explosion-proof score line can avoid the occurrence of cracks caused by the original V-shaped sharp corners during the processing of the explosion-proof score line, thereby improving the processing stability of the explosion-proof score line.

[0034] Example 2

[0035] The present invention focuses on protecting the battery cover structure, but for ease of understanding, this embodiment is used to illustrate the recommended assembly process sequence of the battery cover described in the present invention. First, the cover is welded to the battery shell. After welding, the assembled coil with the current collecting disk is placed into the shell. After entering the shell, the current collecting disk and the cover are pressed by external pressure to ensure that they are in full contact. Then, laser penetration welding is used to weld the outer welding groove of the cover, and then penetration welding is performed at the central welding groove 9 of the cover. The two welding processes fully ensure the welding effect between the cover and the current collecting disk. Then, the other end of the battery cell is assembled. After the assembly is completed, liquid is injected. After the liquid is injected, the sealing pin 12 is sealed and welded to complete the assembly of the entire cylindrical battery cell. Alternatively, the cover and the coil with the current collecting disk are laser welded first, and then the whole is placed into the shell after welding, and then the cover and the shell are welded.

[0036] In addition to the above-mentioned embodiments, within the scope disclosed in the claims and description of the present invention, the technical features or technical data of the present invention can be reselected and combined to form new embodiments. These can be achieved by those skilled in the art without creative work. Therefore, these embodiments that are not described in detail in the present invention should also be regarded as specific embodiments of the present invention and within the scope of protection of the present invention.

Claims

1. A battery cover structure, characterized in that: The invention comprises an inner explosion-proof groove (1), the inner explosion-proof groove (1) is located on the back side of a cover plate and is distributed in an annular manner, the back side of the cover plate is provided with a plurality of inner liquid injection holes (3) distributed along the circumference of the cover plate, the back side of the inner explosion-proof groove (1) is provided with an outer explosion-proof groove (2), the outer explosion-proof groove (2) is distributed in an annular manner, an explosion-proof engraved line (5) is provided at the center of the outer explosion-proof groove (2), and the front side of the cover plate is provided with a plurality of outer liquid injection holes (4) distributed along the circumference of the cover plate, the inner liquid injection holes (3) and the outer liquid injection holes (4) corresponding to each other one by one.

2. A battery cover structure according to claim 1, characterized in that: The depth of the explosion-proof engraved line (5) is less than the thickness of the outer explosion-proof groove (2), the cross-sectional shape of the explosion-proof engraved line (5) is an open U-shape, the cross-sectional shape opening angle of the explosion-proof engraved line (5) is greater than or equal to 10 degrees and less than or equal to 60 degrees, and the cross-sectional shape of the explosion-proof engraved line (5) has an arc-shaped bottom.

3. A battery cover structure according to claim 1, characterized in that: The front side of the cover plate is provided with a welding groove (6), the welding groove (6) is annular, the welding groove (6) is closer to the center of the cover plate than the external explosion-proof groove (2), the external injection hole (4) is closer to the center of the cover plate than the welding groove (6), the opening of the welding groove (6) faces the front side of the cover plate, the depth of the welding groove (6) is less than the thickness of the cover plate, and the welding groove (6) can be set to be circular, semicircular or segmented arc.

4. A battery cover structure according to claim 1, characterized in that: The inner liquid injection hole (3) is closer to the center of the cover plate than the inner explosion-proof groove (1); the diameter of the inner liquid injection hole (3) is greater than the diameter of the outer liquid injection hole (4); the outer liquid injection hole (4) is inscribed in the inner liquid injection hole (3); the inner liquid injection hole (3) and the outer liquid injection hole (4) form a through hole as a whole; the sum of the thickness of the inner liquid injection hole (3) and the thickness of the outer liquid injection hole (4) is equal to the thickness of the cover plate.

5. A battery cover structure according to claim 3, characterized in that: The front surface of the cover plate is provided with a liquid injection hole boss (7), the liquid injection hole boss (7) is closer to the center of the cover plate than the welding groove (6), the external liquid injection hole (4) is closer to the center of the cover plate than the liquid injection hole boss (7), the liquid injection hole boss (7) is annular as a whole, the cross-sectional shape of the liquid injection hole boss (7) is a right-angled trapezoid, the hypotenuse of the right-angled trapezoid is located on the side close to the external liquid injection hole (4), and a gap is left between the liquid injection hole boss (7) and the external liquid injection hole (4).

6. A battery cover structure according to claim 3, characterized in that: A central welding groove (9) is provided at the centre of the front face of the cover plate, the depth of the central welding groove (9) being the same as the depth of the welding groove (6), and the external liquid injection hole (4) being located outside the central welding groove (9).

7. A battery cover structure according to claim 6, characterized in that: An external liquid injection hole circle (8) is provided on the front side of the cover plate, the external liquid injection hole (4) is inscribed in the external liquid injection hole circle (8), the central welding groove (9) and the external liquid injection hole circle (8) are concentric, and the diameter of the central welding groove (9) is smaller than the diameter of the external liquid injection hole circle (8).

8. A battery cover structure according to claim 1, characterized in that: The cover plate is in the shape of a disk as a whole, and an edge groove (10) is provided on the edge of the back side of the cover plate. The edge groove (10) is in the shape of a ring, and the edge groove (10) is further away from the center of the cover plate than the inner explosion-proof groove (1).

9. A battery cover structure according to claim 5, characterized in that: The annular inner wall of the injection hole boss (7) forms a truncated cone structure (11), and the truncated cone structure (11) is provided with a sealing pin (12) matched therewith, the edge shape of the sealing pin (12) matches the edge shape of the truncated cone structure (11), and the thickness of the sealing pin (12) is less than the height of the injection hole boss (7).

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