Lithium battery cover plate and preparation method thereof

Abstract

The invention discloses a lithium battery cover plate and a preparation method thereof. The lithium battery cover plate is characterized in that a top cover sheet is provided with a through hole and an inner sinking table; one end of a pole of the pole assembly penetrates through the through hole and is exposed out of the through hole; the pole assembly comprises a pole, a coating piece and a connecting substrate, the pole is arranged in a stepped manner and is provided with a first stepped part and a second stepped part; the cross section of the wrapping piece is in a C shape, the wrapping piece wraps the periphery of the second step part, a plurality of fixing parts are further arranged on the lower surface of the wrapping piece in a protruding mode, and the length of the fixing parts is larger than the sum of the thickness of the connecting base plate and the thickness of the bottom cover plate. The bottom cover plate is arranged below the wrapping piece and located on the inner sinking table of the top cover piece, and the bottom cover plate is fixed to the top cover piece through welding; one end of the fixing part sequentially penetrates out of the assembly holes of the connecting substrate and the bottom cover plate, and forms a fixing inverted buckle in a hot melting manner; the invention provides a lithium battery cover plate. The problems that an existing battery cover plate is insufficient in sealing performance, the deformation quantity of a sealing piece is difficult to determine, and a bottom cover plate is prone to falling off are solved.

Description

Technical Field

[0001] The present invention relates to the field of lithium battery cover plates, and in particular to a lithium battery cover plate and a preparation method thereof. Background Art

[0002] The rapid development of new energy vehicles and energy storage industries has driven the rapid growth of my country's lithium-ion battery demand, and the demand for lithium-ion battery terminals has also increased significantly. With the rapid development of the battery terminal industry and the improvement of the product requirements of the OEMs, various battery terminal companies have launched fierce competition to occupy more market shares, resulting in an increasing number and types of battery terminals, and the quality of products has been improved and the prices have been lowered. In this context, many battery terminal suppliers, in order to maintain the competitiveness of the battery terminals they supply and maintain or even increase the profits of their products, must find more optimized terminal designs in various links such as product design and development, production, and supply, and reduce costs while ensuring product quality.

[0003] At present, the battery cover plate junctions of most battery terminal manufacturers are too complicated and costly. More importantly, in terms of sealing performance and electrical performance, the overall volume of the pole is large and requires secondary injection molding to complete its axial loosening. Therefore, it is improved to reduce the volume of the pole, such as the publication number: CN117134049A, named a low-resistance lithium battery cover plate junction. This method can reduce the axial height of the pole, and at the same time, there is no need to shape the front of the cover body through secondary injection molding; however, this method still has certain defects: (1) The sealing performance is difficult to determine. In this method, the axial limit of the pole is achieved by the cover plate and the mounting ring to clamp the pole and the seal. However, since the outer ring of the mounting ring needs to form a step for the bottom pressure plate to be clamped, there is a mounting position between the mounting ring and the cover plate, which means that the welding position where the mounting ring and the cover plate are connected needs to be avoided. (1) The circumference is welded, which can only be achieved by penetration welding. However, this penetration welding method is difficult to ensure the uniformity and firmness of the welding, and it is even more difficult to ensure the tightness of the welding. If the welding transition occurs, the sealing part of the mounting ring and the cover plate will be directly compressed and transitioned, which will greatly reduce the service life of the sealing part and cause rapid wear and tear. If the welding position is insufficient or there is a welding leak, the sealing part will not be compressed enough and will not have a sealing effect. (2) The bottom pressure cover is easy to fall off, and the mounting cover is affected by external bumps and external forces on the vehicle. The clamping method cannot ensure the overall firmness. If the connection point falls off, it is easy to cause risks such as battery fluid leakage. (3) The position of the mounting ring is not accurately limited before welding, which is easy to deviate during the welding process and misalignment. The centering effect of the pillar and the sealing ring cannot be guaranteed. If warping occurs, the sealing of the sealing ring will be greatly reduced.

[0004] In summary, the existing lithium battery cover needs to be further improved. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned defects or problems existing in the background technology, and to provide a lithium battery cover plate, which has a very simple structure, is easy to manufacture, easy to implement and has low cost, and solves the problems of insufficient sealing of the existing battery cover plate, difficulty in determining the deformation amount of the seal, and easy falling off of the bottom cover plate.

[0006] In order to achieve the above purpose, this invention adopts the following technical solutions:

[0007] A lithium battery cover plate, which is used for sealing and is arranged on a battery box body; the battery cover plate comprises: a top cover plate, a pillar assembly, a seal and a bottom cover plate;

[0008] A top cover sheet, which is used for sealing and welding to the battery box body, and the top cover sheet is provided with a through hole and an inner sinking platform; the through hole is used for one end of the pole of the pole assembly to pass through and be exposed; the inner sinking platform is used for the pole assembly to limit the position;

[0009] A pole assembly is arranged between the top cover sheet and the bottom cover plate; the pole assembly comprises a pole, a covering member and a connecting substrate; the pole is arranged in a stepped manner and is arranged into a first step portion and a second step portion; the covering member has a C-shaped cross section and covers around the second step portion, and limits the circumferential movement of the pole by a limiting structure; a plurality of fixing portions are also protruded from the lower surface of the covering member, and the length of the fixing portions is greater than the sum of the thicknesses of the connecting substrate and the bottom cover plate; the bottom cover plate is arranged below the covering member and is located at the inner sink of the top cover sheet, and the bottom cover plate is fixed to the top cover sheet by welding;

[0010] A sealing member, which is sleeved on the outer periphery of the first step portion of the pillar and falls between the covering member and the outer periphery of the first step portion;

[0011] A bottom cover plate is disposed below the connection substrate and has a connection hole for the fixing part to pass through;

[0012] One end of the fixing portion sequentially passes through the matching holes of the base plate and the bottom cover plate, and forms a fixing undercut by hot melting to prevent the bottom cover plate from falling off.

[0013] Furthermore, an embedding groove is formed inwardly on the outer circumference of the covering member, and the annular connecting substrate is embedded therein, so that the covering member and the connecting substrate are fixedly connected together, and the height of the covering member and the connecting substrate is limited.

[0014] Furthermore, the upper edge of the covering member covers the peripheral wall and a part of the upper surface of the second stepped portion of the pole inwardly, so that the upper surface of the second stepped portion forms a ring groove for limiting the sealing member to be positioned; the ring groove is used to limit the transitional deformation of the sealing member outward.

[0015] Furthermore, the limiting structure includes a protrusion formed on the inner wall of the covering and an engaging portion not located on the outer periphery of the second step portion; the covering is plastic-molded corresponding to the second step portion of the pillar, and the protrusion and the engaging portion correspond to each other, so that the covering, the pillar and the connecting substrate are connected as a whole.

[0016] Furthermore, the inner sinker of the top cover piece is arranged in a stepped manner, and is continuously arranged from the lower surface inward into a first sinker and a second sinker, the first sinker is provided for limiting the sealing part and the covering part; the second sinker is provided for connecting the substrate, and the periphery of the second sinker and / or the sinker surface are welded together.

[0017] Furthermore, the cross-sectional shape of the seal is "convex"; the seal is sleeved on the inner wall of the through hole of the partially non-top cover sheet on the first step portion with interference fit, and is clamped on the inner surface of the partially non-top cover sheet on the second step portion to form a secondary seal.

[0018] Furthermore, a convex ring is formed downwardly at the edge of the top cover sheet corresponding to the through hole, and the convex ring is used to press against the sealing member to form a triple seal.

[0019] Furthermore, it also includes an explosion-proof valve assembly, which is welded or riveted to the through hole in the middle of the top cover sheet, so as to tear and release the pressure when the internal pressure is too large; the explosion-proof valve assembly includes an explosion-proof plate and an explosion-proof membrane, and the explosion-proof plate is fixed to the top cover sheet and sealed by the explosion-proof membrane.

[0020] Furthermore, a liquid injection hole is provided on the top cover sheet, the edge of the outer surface of which is inclined inwardly, and a reverse thrust groove is punched on the inner surface of the top cover sheet corresponding to the edge position to make the edge and the hole position flat.

[0021] A method for preparing a lithium battery cover plate, the method comprising the following steps:

[0022] Step 1: Use aluminum material to prepare the top cover sheet, and form the through hole, the inner sink, the injection hole and the through hole through a stretch punching die; wherein, after the injection hole is punched downward from the upper surface, a reverse groove is punched from the lower surface at the position corresponding to the edge and the hole position;

[0023] Step 2: Using copper or copper-aluminum composite materials to prepare a thin pole, wherein the pole has a first step portion, a second step portion and a fitting portion;

[0024] Step 3: Prepare a connecting substrate, which is formed into an annular sheet by stamping; after forming, put it into an injection mold, and prepare a covering part by secondary injection molding, and make the three parts not integral; the outer periphery of the covering part is not connected to the substrate, and the upper part covers the outer periphery and the upper surface of the second step portion; the lower surface of the covering part also extends a plurality of fixing parts, the length of which is greater than the sum of the thickness of the connecting substrate and the bottom cover plate, so as to be fixed by hot melt after the bottom cover plate is subsequently installed;

[0025] Step 4: a convex-shaped sealing member is sleeved on the outer periphery of the first step portion of the pole and falls on the second step portion; then the non-pole assembly is integrally inserted into the inner sink of the top cover plate, at which time the outer periphery of the sealing member and the inner hole wall of the non-through hole are interference-fitted to form the first seal, the through hole is located at the edge of the lower surface to form a convex ring and the non-sealing member to form the second seal, and the upper and lower surfaces of the sealing member are clamped by the non-covering member of the top cover plate to form a third seal;

[0026] Step 5: Place the connecting substrate in the second sink of the top cover sheet, and fix the two by laser welding;

[0027] Step 6: After the bottom cover plate is injection molded, it is correspondingly sleeved on the fixing part so that the free end of the fixing part is exposed on the bottom cover plate. After the fixing part is hot-melted by high-temperature hot-melting, a mushroom-shaped fixing undercut is formed by pressing to fix the top cover plate to the lower surface of the top cover sheet;

[0028] Step 7: Weld the determined explosion-proof plate to the through hole of the top cover plate, and attach the explosion-proof membrane to the explosion-proof plate after forming.

[0029] From the above description of the present invention, it can be seen that compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention provides a lithium battery cover plate, which has a very simple structure, is easy to manufacture, easy to implement and has low cost. First, the present invention greatly reduces the thickness of the column and makes it thinner to achieve a low-resistance current-seeking effect. The thickness of the entire battery cover plate is greatly reduced, and the current-seeking property is good, the heat dissipation is high and the cost is reduced. On this basis, the present invention wraps the column around the circumference through a covering member, and at the same time fixes the connecting substrate together to form a column assembly, thereby ensuring that the dimensions of the column, the covering member and the connecting substrate in the entire assembly are more accurate, thereby ensuring that the deformation of the sealing member clamped by the connecting substrate after welding with the top cover sheet is small. The most important thing is that the connection between the base plate and the top cover plate can be circumferentially welded by laser welding to ensure the overall flatness, without the need for penetration welding to avoid transition deformation and deformation of the pillars caused by high temperature. Moreover, the fixing portion extending from the lower surface of the covering passes through the connection between the base plate and the bottom cover plate, and a mushroom-shaped fixing undercut is formed by hot melting to ensure the stable connection of the bottom cover plate. This ingenious design, which is linked together, can simultaneously achieve the advantages of determining the deformation amount of the seal, reducing the deformation of the thin pillars affected by the heat seeking of welding, making the welding track smooth and not prone to loose welding, and ensuring a stable and fixed connection of the bottom cover plate.

[0031] (2) The cover of the present invention is also provided with a mounting ring groove, which makes it easy to fit the sealing member when the sealing member is mounted and is not prone to deflection; at the same time, it limits the transitional deformation of the sealing member in the radial direction outward, thus playing a double limiting role.

[0032] (3) The inner sink on the top cover of the present invention is set as a stepped structure, which is used to form a limit to ensure the accuracy of the size. Combined with the precise size of the pole assembly, the deformation of the seal after assembly is guaranteed (that is, the deformation of the seal is well controlled, and it will not deform to the point of not sealing, nor will it deform excessively and reduce the life). At the same time, it provides a good welding position for connecting the substrate, and the heat generated during the welding process will not quickly find the pole column, causing the pole column to deform;

[0033] (4) The present invention sets the seal in a convex shape, so that the top cover sheet forms a secondary seal and protection around the column, which plays a role in dustproof, waterproof and insulation; and a third seal is formed under the action of the convex ring, further strengthening the sealing and preventing the leakage of internal electrolyte.

[0034] (5) The present invention provides a reverse thrust groove at the injection hole to prevent the injection hole from being irregularly opened, which may result in the hole corners being unable to be sealed during plugging. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 This is a schematic diagram of the three-dimensional exploded structure of the lithium battery cover plate of the present invention;

[0037] Figure 2 This is a schematic diagram of the three-dimensional structure of the lithium battery cover plate of the present invention;

[0038] Figure 3 is a cross-sectional view of the lithium battery cover plate of the present invention;

[0039] Figure 4 Schematic diagram of the three-dimensional exploded structure of the electrode assembly of the present invention;

[0040] Figure 5 Schematic diagram of the three-dimensional structure of the electrode assembly of the present invention;

[0041] Figure 6 A bottom view of the top cover sheet of the present invention;

[0042] Figure 7 For the purposes of this disclosure Figure 6 Sectional view of part A in the middle. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are preferred embodiments of the present invention and should not be regarded as excluding other embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] In the claims, description and drawings of the present invention, unless otherwise clearly defined, the use of terms such as "first", "second" or "third", etc., are intended to distinguish different objects rather than to describe a specific order.

[0045] In the claims, specification and the above-mentioned drawings of the present invention, unless otherwise expressly defined, directional words, such as the terms "center", "lateral", "longitudinal", "horizontal", "vertical", "top", "bottom", "inside", "outside", "up", "down", "front", "back", "left", "right", "clockwise", "counterclockwise", etc., indicating directions or positional relationships are based on the directions and positional relationships shown in the drawings, and are only for the convenience of narrating the present invention and simplifying the description, and do not indicate or imply that the arrangement or component referred to must have a specific orientation or be constructed and operated in a specific orientation, so they cannot be understood as limiting the specific protection scope of the present invention.

[0046] In the claims, specification and the above drawings of this invention, unless otherwise clearly defined, if the terms "fixed connection" or "fixed connection" are used, they should be understood in a broad sense, that is, any connection method without any positional relationship and relative rotation relationship between the two, that is to say, including non-detachable fixed connection, detachable fixed connection, integral connection and fixed connection through other devices or elements.

[0047] In the claims, description and drawings of the present invention, if the terms "include", "have" and their variations are used, they are intended to mean "including but not limited to".

[0048] See also Figure 1-4 The lithium battery cover plate described in the present invention is used for sealing the cover and is arranged at the opening of the battery box body to form a complete lithium battery shell, and then the battery liquid is injected to form a lithium battery;

[0049] The battery cover plate described in this embodiment includes: a top cover plate 1, a pole 2, a covering member 3, a connecting substrate 4, a sealing member 5, a bottom cover plate 6, an explosion-proof plate 7 and an explosion-proof membrane 8;

[0050] The top cover sheet 1 is formed by stamping aluminum and is used for sealing and welding to the battery box body. The top cover sheet 1 is provided with a through hole 11, an inner sinking platform 12, a liquid injection hole 13 and a through hole 14 for welding the explosion-proof sheet 7; wherein the through hole 11 is used for one end of the pole 2 of the pole 2 assembly to pass through and be exposed; the inner sinking platform 12 is used for the limit setting of the pole 2 assembly; the liquid injection hole 13 is used for injecting battery liquid into the battery box body and then sealing it;

[0051] In this embodiment, as shown in Figures 6 and 7, the inner recessed platform 12 of the top cover piece 1 is arranged in a stepped manner, and is continuously arranged from the lower surface inward into a first recessed platform 121 and a second recessed platform 122, wherein the first recessed platform 121 is provided for limiting the sealing component 5 and the covering component 3; the second recessed platform 122 is provided for connecting the substrate 4, and the periphery and / or the recessed platform surface of the second recessed platform 122 are welded together.

[0052] A pole 2 assembly, which is disposed between the top cover sheet 1 and the bottom cover sheet 6;

[0053] The pole 2 assembly of this embodiment includes a pole 2, a covering member 3 and a connecting substrate 4;

[0054] The pillar 2 is arranged in a stepped manner and is divided into a first stepped portion 21 and a second stepped portion 22. It should be noted that the pillar 2 of this embodiment is thin in overall thickness and is formed and manufactured using a copper material or a copper-aluminum composite material.

[0055] The covering member 3 has a C-shaped cross section and covers around the second step portion 22, and limits the circumferential movement of the pole 2 through the limiting junction 9; it should be noted that the covering member 3 is an insulating material, such as plastic, and wraps the second step portion 22 of the pole 2 by secondary injection molding;

[0056] The outer circumference of the covering member 3 is formed with an embedding groove 31 inwardly, into which the annular connecting substrate 4 is embedded, so that the covering member 3 and the connecting substrate 4 are fixedly connected together to limit the height of the covering member 3 and the connecting substrate 4, so as to ensure the height dimension of the covering member 3 and the pillar 2. By controlling this dimension, the deformation and compression amount of the sealing member 5 can be more accurately controlled during the subsequent fitting.

[0057] The limiting junction 9 here includes a protrusion 91 formed on the inner wall of the covering 3 and an engaging portion 92 which is not located on the outer periphery of the second stepped portion 22; the covering 3 is overmolded corresponding to the second stepped portion 22 of the pillar 2, and the protrusion 91 and the engaging portion 92 correspond to each other, so that the covering 3, the pillar 2 and the connecting substrate 4 are connected as a whole, so that the size of the entire pillar 2 assembly can be precisely controlled.

[0058] In addition, the upper edge of the covering member 3 inwardly covers the peripheral wall and a part of the upper surface of the second stepped portion 22 of the pillar 2, so that the upper surface of the second stepped portion 22 forms a mounting ring groove A for limiting the position of the seal 5; the mounting ring groove A is used to limit the transitional deformation of the seal 5, that is, to achieve precise positioning when installing the seal 5, and at the same time prevent the seal 5 from transitioning to deform outward. In other words, the deformation of the seal 5 can be accurately controlled by the mounting ring groove A.

[0059] Moreover, a plurality of fixing portions 32 are protruded from the lower surface of the covering member 3, and the length of the fixing portion 32 is greater than the sum of the thicknesses of the connecting substrate 4 and the bottom cover plate 6; wherein one end of the fixing portion 32 passes through the matching holes 61 of the connecting substrate 4 and the bottom cover plate 6 in sequence, and a fixing undercut is formed by hot melting to prevent the bottom cover plate 6 from falling off.

[0060] The connecting substrate 4 is arranged below the covering member 3 and located at the inner sink 12 of the top cover sheet 1. The bottom cover plate 6 is fixed to the top cover sheet 1 by welding. The welding here is preferably laser welding, which has a small weld seam and high precision. The connecting substrate 4 is almost flush with the lower surface of the top cover sheet 1. In this way, the circumference of the connecting substrate 4 is welded, and the stability after welding is high and it is not easy to leak.

[0061] The sealing member 5 is sleeved on the outer periphery of the first stepped portion 21 of the pillar 2, and falls between the outer periphery of the covering member 3 and the first stepped portion 21; it should be noted that the sealing member 5 of the present embodiment adopts a sealing member 5 with a "convex" cross-sectional shape; the sealing member 5 is sleeved on the inner wall of the through hole 11 of the part of the first stepped portion 21 that is not the top cover sheet 1 with an interference fit, and is clamped on the inner surface of the part of the top cover sheet 1 placed on the second stepped portion 22 to form a secondary seal.

[0062] The bottom cover plate 6 is disposed below the connecting substrate 4 and has a connecting hole for the fixing portion 32 to pass through;

[0063] It also includes an explosion-proof valve assembly, which is welded or riveted to the through hole 14 in the middle of the top cover sheet 1, so as to tear and release the pressure when the internal pressure is too large; the explosion-proof valve assembly includes an explosion-proof sheet 7 and an explosion-proof membrane 8, and the explosion-proof sheet 7 is fixed to the top cover sheet 1 and sealed by the explosion-proof membrane 8.

[0064] The top cover sheet 1 is also provided with a liquid injection hole 13, the edge of the outer surface of which is inclined inwardly, and a reverse thrust groove 15 is punched on the inner surface of the top cover sheet 1 corresponding to the edge position to make the edge and the hole position flat.

[0065] More specifically, a convex ring 16 is formed downwardly at the edge of the top cover sheet 1 corresponding to the through hole 11 , and the convex ring 16 is used to press against the sealing member 5 to form a triple seal.

[0066] In actual preparation: Figure 1-7 As shown;

[0067] (1) A top cover sheet 1 is prepared using aluminum material, and a through hole 11, a first sink 121, a second sink 122, a liquid injection hole 13 and a through hole 14 are formed by a stretch punching die; wherein, when preparing the liquid injection hole 13, since the aperture of the liquid injection hole 13 is small and the aluminum material is relatively flexible, the liquid injection hole 13 is punched from the front of the top cover sheet 1, and then a reverse groove 15 is punched from the lower surface of the top cover sheet 1 and at the position corresponding to the edge and the hole position, so that the edge of the entire liquid injection hole 13 is flat, and no gap is formed at the edge when the plunger is subsequently placed, thereby improving the sealing performance;

[0068] (2) A thin column 2 is prepared using a copper material or a copper-aluminum composite material, and after cutting, the column 2 is finely trimmed to adjust the outer dimensions so as to form a column 2 having a first step portion 21, a second step portion 22 and a fitting portion 92, and the column 2 is prepared for use;

[0069] (3) The connecting substrate 4 is prepared by stamping into a ring-shaped sheet. After the forming, the non-column 2 is put into the injection mold, and the covering part 3 is prepared by secondary injection molding, so that the three are not formed as one. At this time, the outer periphery of the covering part 3 is formed for the connecting substrate 4 to be embedded, and the upper part covers the outer periphery and the upper surface of the second step part 22. The height dimension between the three is more accurate through injection molding, which is convenient for the subsequent non-top cover sheet 1 to be assembled, and the deformation of the sealing part 5 can be accurately controlled;

[0070] It should also be noted that a plurality of fixing portions 32 are extended from the lower surface of the covering member 3. The length of the fixing portions 32 is greater than the sum of the thicknesses of the connecting substrate 4 and the bottom cover plate 6, so as to be fixed by hot melt after the bottom cover plate 6 is subsequently installed.

[0071] (4) The convex-shaped sealing member 5 is sleeved on the outer periphery of the first step portion 21 of the pillar 2 and falls on the second step portion 22, and then it is integrally inserted into the inner sink 12 of the top cover plate 1. At this time, the outer periphery of the sealing member 5 is interference-fitted with the inner hole wall of the non-through hole 11 to form the first seal, that is, the primary seal (for dustproof, waterproof, and leakage-proof). The through hole 11 is located at the edge of the lower surface to form a convex ring 16, and the non-sealing member 5 forms the second seal, that is, the secondary seal; the upper and lower surfaces of the sealing member 5 are clamped by the non-covering member 3 of the top cover plate to form a tertiary seal to prevent battery liquid leakage;

[0072] (5) The connecting substrate 4 is located in the second sinking platform of the top cover sheet 1, and the two are fixed by laser welding; after this part is fixed, since the dimensions of each part of the inner sinking platform 12 and the pillar 2 components are accurate, the position is determined before welding and the accurately calculated pressure is applied, so the deformation of the sealing member 5 can be accurately determined, and then the sealing is controlled to ensure good sealing without excessive compression, that is, the sealing is excellent, the service life is long, and no anatomical detection is required;

[0073] (6) After the bottom cover plate 6 is injection molded, it is correspondingly sleeved on the fixing portion 32 so that the free end of the fixing portion 32 is exposed on the bottom cover plate 6. After the fixing portion 32 is hot-melted by high-temperature hot-melting, a mushroom-shaped fixing undercut is formed by pressing, so that the top cover plate is fixed to the lower surface of the top cover sheet 1;

[0074] (7) The determined explosion-proof plate 7 is welded to the through hole 14 of the top cover plate 1. After forming, the explosion-proof membrane 8 is attached to the explosion-proof plate 7 to play a role of dustproof and waterproof;

[0075] (8) The entire battery cover and the battery box are welded together, and then the liquid injection hole 13 is injected, that is, the battery liquid is injected, and then the liquid injection hole 13 is blocked to complete the preparation of the entire lithium battery.

[0076] The present invention provides a lithium battery cover plate, which has a very simple structure, is easy to manufacture, easy to implement and has low cost. First, the present invention greatly reduces the thickness of the pole and makes it thinner to achieve a low-resistance current-seeking effect. The thickness of the entire battery cover plate is greatly reduced, and the current-seeking property is good, the heat dissipation is high and the cost is reduced. On this basis, the present invention wraps the pole around the pole through a covering member, and at the same time fixes the connecting substrate together to form a pole-column assembly, thereby ensuring that the dimensions of the pole, the covering member and the connecting substrate in the entire assembly are more accurate, thereby ensuring that the deformation of the clamped seal is obtained after the connecting substrate is welded to the top cover sheet. To ensure that, the most important thing is that the connection between the base plate and the top cover plate can be welded around by laser welding to ensure the overall flatness, without the need for welding by penetration welding, avoiding transition deformation and high temperature affecting the deformation of the column. Not only that, the fixed part extending from the lower surface of the cover penetrates the connection between the base plate and the bottom cover plate, and the mushroom-shaped fixed undercut is formed by hot melting to ensure the stable connection of the bottom cover plate. Such a clever design that is linked together can simultaneously achieve the advantages of determining the deformation of the seal, reducing the deformation of the thin column affected by the heat seeking of welding, making the welding track flat and not prone to loose welding, and firmly fixing the bottom cover plate. The cover of the present invention is also provided with a mounting ring groove, that is, it can be easily matched when the seal is installed and not easily deflected; at the same time, it limits the transition deformation of the seal radially outward, playing a double limiting role. The inner sink on the top cover sheet of the present invention is set as a stepped structure, and the stepped structure is used to form a limit to ensure the accuracy of the size. Combined with the precise size of the electrode assembly, the deformation of the seal after assembly is guaranteed (that is, the deformation of the seal is controlled so that it will not deform to the point of not sealing, and will not deform excessively to reduce the life). At the same time, a good welding position for connecting the substrate is provided, and the heat generated during the welding process will not quickly find the pole column, causing the pole column to deform; the present invention sets the seal to be convex, so that the top cover sheet forms a secondary seal and protection around the pole column, which plays a role in dustproof, waterproof and insulation; and a tertiary seal is formed under the action of the convex ring, further strengthening the sealing and preventing the leakage of the internal electrolyte. The present invention sets a reverse thrust groove at the injection hole to prevent the injection hole from being irregular when it is opened, resulting in the situation that the corners of the hole cannot be sealed when it is blocked.

[0077] The above specification and description of the embodiments are used to explain the protection scope of the present invention, but they are not intended to limit the protection scope of the present invention.

Claims

1. A lithium battery cover plate, which is used for sealing the cover and is arranged on the battery box body; characterized in that: The battery cover plate includes: a top cover plate, a pole assembly, a seal and a bottom cover plate; A top cover sheet is used for sealing and welding to the battery box body, and a through hole and an inner recess are provided on the top cover sheet; the through hole is used for one end of the pole of the pole assembly to pass through and be exposed; the inner recess is used for limiting the installation of the pole assembly; A pole assembly is arranged between a top cover sheet and a bottom cover sheet; the pole assembly comprises a pole, a covering member and a connecting substrate; the pole is arranged in a stepped manner and is arranged into a first step portion and a second step portion; the covering member has a C-shaped cross section and covers around the second step portion, and limits the circumferential movement of the pole by a limiting structure; a plurality of fixing portions are also protruded from the lower surface of the covering member, and the length of the fixing portions is greater than the sum of the thicknesses of the connecting substrate and the bottom cover sheet; the bottom cover sheet is arranged below the covering member and is located on the inner sink of the top cover sheet, and the bottom cover sheet is fixed to the top cover sheet by welding; A sealing member, which is sleeved on the outer periphery of the first step portion of the pole and falls between the covering member and the outer periphery of the first step portion; A bottom cover plate, which is arranged below the connecting substrate and has a mounting hole for the fixing part to pass through; One end of the fixing portion sequentially passes through the assembly holes connecting the substrate and the bottom cover plate, and forms a fixing undercut by hot melting to prevent the bottom cover plate from falling off.

2. A lithium battery cover as claimed in claim 1, characterized in that: An embedding groove is formed inwardly on the outer circumference of the covering member, and the annular connecting substrate is embedded therein, so that the covering member and the connecting substrate are fixedly connected as one body, and the height of the covering member and the connecting substrate is limited.

3. A lithium battery cover as claimed in claim 2, characterized in that: The upper edge of the covering member covers the peripheral wall and a part of the upper surface of the second stepped portion of the pole inwardly, so that the upper surface of the second stepped portion forms an installation ring groove for the sealing member to limit the outward transition deformation of the sealing member.

4. A lithium battery cover as claimed in claim 3, characterized in that: The limiting structure includes a protrusion formed on the inner wall of the covering member and an engaging portion located on the outer periphery of the second stepped portion; the covering member is plastic-molded corresponding to the second stepped portion of the pole, and the protrusion and the engaging portion are matched to form the covering member, the pole and the connecting substrate as a whole.

5. A lithium battery cover as claimed in claim 4, characterized in that: The inner sinker of the top cover piece is arranged in a stepped manner, and is arranged inwardly into a continuous first sinker and a second sinker, wherein the first sinker is used for limiting the installation of the sealing member and the covering member; the second sinker is used for installing the connecting substrate, and is welded to the periphery and / or the sinker surface of the second sinker.

6. A lithium battery cover as claimed in claim 5, characterized in that: The cross-section of the seal is convex; the portion of the seal sleeved on the first step is interference fit with the inner wall of the through hole of the top cover sheet, and the portion placed on the second step is clamped with the inner surface of the top cover sheet to form a secondary seal.

7. A lithium battery cover as claimed in claim 6, characterized in that The top cover sheet forms a convex ring downwardly at the edge of the through hole corresponding to the through hole, and the convex ring is used to press against the sealing member to form a triple seal.

8. A lithium battery cover as claimed in claim 1, characterized in that: It also includes an explosion-proof valve assembly, which is welded or riveted to the through hole in the middle of the top cover sheet to tear and release pressure when the internal pressure is too large; the explosion-proof valve assembly includes an explosion-proof plate and an explosion-proof membrane, the explosion-proof plate is fixedly mounted on the top cover sheet and sealed by the explosion-proof membrane.

9. A lithium battery cover as claimed in claim 1, characterized in that: The top cover sheet is also provided with a liquid injection hole, the edge of the outer surface of which is inclined inwardly, and a reverse thrust groove is punched on the inner surface of the top cover sheet corresponding to the edge position to make the edge and the hole position flat.

10. A method for preparing a lithium battery cover plate according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: Step 1: Use aluminum material to prepare the top cover sheet, and form the through hole, the inner sink, the injection hole and the through hole through a stretch punching die; wherein, after the injection hole is punched downward from the upper surface, a reverse groove is punched from the lower surface at the position corresponding to the edge and the hole position; Step 2: A thin pole is prepared by using copper or copper-aluminum composite material, and the pole has a first step portion, a second step portion and a fitting portion; Step 3: A connecting substrate is prepared, which is formed into an annular sheet by stamping; after forming, it is placed in an injection mold together with the pole, and a covering piece is prepared by secondary injection molding, and the three are formed into one; the outer periphery of the covering piece is fitted with the connecting substrate, and the upper part covers the outer periphery and the upper surface of the second step portion; a plurality of fixing parts are extended from the lower surface of the covering piece, and the length of the fixing part is greater than the sum of the thickness of the connecting substrate and the bottom cover plate, so as to be fixed by hot melt after the bottom cover plate is subsequently installed; Step 4: a convex-shaped sealing member is sleeved on the outer periphery of the first step portion of the pole and falls on the second step portion; then the sealing member and the pole assembly are integrally installed into the inner sink of the top cover plate, at which time the outer periphery of the sealing member and the inner hole wall of the through hole are interference-fitted to form a first seal, the through hole is located at the edge of the lower surface to form a convex ring and the sealing member to form a second seal, and the upper and lower surfaces of the sealing member are clamped by the top cover plate and the covering member to form a third seal; Step 5: Place the connection substrate in the second sink of the top cover sheet, and fix the two by laser welding; Step 6: After the bottom cover plate is injection molded, it is correspondingly sleeved on the fixing part so that the free end of the fixing part is exposed on the bottom cover plate. After the fixing part is hot-melted by high-temperature hot-melting, a mushroom-shaped fixing undercut is formed by pressing to fix the top cover plate to the lower surface of the top cover sheet; Step 7: Weld the determined explosion-proof plate to the through hole of the top cover plate, and attach the explosion-proof membrane to the explosion-proof plate after forming.

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