End cover and manufacturing method thereof, energy storage device and electric equipment

Abstract

The invention discloses an end cover, a manufacturing method thereof, an energy storage device and electric equipment. The end cap includes a first surface and a second surface. The first surface and the second surface are oppositely arranged in the thickness direction of the end cover. The end cover is provided with a liquid injection hole, the liquid injection hole penetrates through the first surface and the second surface in the thickness direction of the end cover, and the liquid injection hole is used for injecting electrolyte into the energy storage device. The first surface comprises a first sub-surface, a second sub-surface and a third sub-surface, and the first sub-surface is arranged around the periphery of the liquid injection hole. The second sub-surface is arranged around the periphery of the first sub-surface and is connected with the first sub-surface. The third sub-surface is arranged around the periphery of the second sub-surface and is connected with the second sub-surface. The surface roughness of the second sub-surface is smaller than the surface roughness of the first sub-surface and the surface roughness of the third sub-surface. According to the end cover, electrolyte can be prevented from permeating into the welding area around the liquid injection hole, and the sealing performance of the sealing piece on the liquid injection hole is improved.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an end cover and a manufacturing method thereof, an energy storage device, and electrical equipment. Background Art

[0002] Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be recharged after discharge to activate the active materials and continue to be used. The end caps of the batteries are usually provided with injection holes, which are used to inject electrolyte into the interior of the battery. Generally speaking, after the electrolyte is injected, it is usually necessary to clean the area around the injection hole to facilitate the subsequent welding of sealing pins to seal the injection hole. However, in the prior art, the electrolyte easily seeps into the cleaned area around the injection hole, affecting the welding effect between the sealing pins and the end cap, and thus affecting the sealing effect of the injection hole. Summary of the Invention

[0003] The present application provides an end cover and a manufacturing method thereof, an energy storage device, and an electrical equipment, which can prevent the electrolyte from penetrating into the welding area around the injection hole and improve the sealing performance of the seal on the injection hole.

[0004] In a first aspect, the present application provides an end cover for use in an energy storage device. The end cover includes a first surface and a second surface. The first surface and the second surface are arranged opposite to each other along the thickness direction of the end cover. The end cover is provided with an injection hole, which passes through the first surface and the second surface along the thickness direction of the end cover, and the injection hole is used to inject electrolyte into the interior of the energy storage device. The first surface includes a first sub-surface, a second sub-surface and a third sub-surface. The first sub-surface is arranged around the periphery of the injection hole. The second sub-surface is arranged around the periphery of the first sub-surface and is connected to the first sub-surface. The third sub-surface is arranged around the periphery of the second sub-surface and is connected to the second sub-surface. The surface roughness of the second sub-surface is smaller than the surface roughness of the first sub-surface and the surface roughness of the third sub-surface.

[0005] In one possible embodiment, the injection hole includes a through hole and a sink, the through hole and the sink are connected and communicated along the thickness direction of the end cap, and the end of the sink facing away from the through hole passes through the first surface. The inner wall surface of the sink includes a bottom surface and a side surface, the side surface is arranged around the periphery of the through hole, and the side surface is connected between the bottom surface and the first sub-surface. The bottom surface includes a first sub-bottom surface and a second sub-bottom surface, the second sub-bottom surface is arranged around the periphery of the through hole and connected to the side wall surface of the through hole. The first sub-bottom surface is arranged around the periphery of the second sub-bottom surface and connected to the second sub-bottom surface. The surface roughness of the second sub-bottom surface is smaller than the surface roughness of the first sub-bottom surface and the surface roughness of the side surface.

[0006] In a possible implementation manner, the surface roughness of the second sub-bottom surface is the same as the surface roughness of the second sub-surface.

[0007] In a possible implementation manner, the surface roughness of the first sub-bottom surface, the surface roughness of the first sub-surface, and the surface roughness of the side surface are all the same.

[0008] In a second aspect, the present application provides a method for manufacturing an end cap. The method for manufacturing the end cap comprises:

[0009] A base end cap is provided, wherein the base end cap is provided with an injection hole, wherein the injection hole penetrates the base end cap along the thickness direction of the base end cap; the base end cap comprises a base surface, wherein the base surface comprises a first region and a second region, wherein the first region is arranged around the periphery of the injection hole, and the second region is arranged around the periphery of the first region; and the base surface further comprises a third sub-surface, wherein the third sub-surface is arranged around the periphery of the second region;

[0010] Cleaning the base surface of the first area using a first laser to form a first sub-surface;

[0011] A second laser is used to clean the base surface of the second area to form a second sub-surface, thereby obtaining an end cap; wherein the surface roughness of the second sub-surface is smaller than the surface roughness of the first sub-surface and the surface roughness of the third sub-surface.

[0012] In one possible embodiment, the injection hole includes a through hole and a sink, the through hole and the sink are connected and communicated along the thickness direction of the base end cap, and the end of the sink facing away from the through hole passes through the base surface. The sink includes a base bottom surface and a base side surface, the base side surface is arranged around the periphery of the through hole, and the base side surface is connected between the base surface and the base bottom surface. The base bottom surface includes a third region and a fourth region, the fourth region is arranged around the periphery of the through hole, and the base bottom surface of the fourth region is connected to the side wall surface of the through hole. The third region is arranged around the periphery of the fourth region, and the base bottom surface of the third region is connected to the base bottom surface of the fourth region.

[0013] The step of "using a first laser to clean the base surface of the first area to form a first sub-surface" also includes: using a first laser to clean the base bottom surface of the third area to form a first sub-bottom surface; using a first laser to clean the base side surface to form a side surface.

[0014] In one possible embodiment, the step of "cleaning the base surface of the second region using a second laser to form a second sub-surface" further includes: cleaning the base bottom surface of the fourth region using a second laser to form a second sub-bottom surface. The surface roughness of the second sub-bottom surface is less than the surface roughness of the first sub-bottom surface and the surface roughness of the side surface.

[0015] In a possible implementation, "using a second laser to clean the base surface of the second area to form a second sub-surface" also includes: using a second laser to clean the base surface of the first area, the base side surface and the base bottom surface of the third area.

[0016] In one possible embodiment, after the step of "using a second laser to clean the base surface of the second area", the method for making the end cover further includes: using a third laser to clean the base surface of the first area, the base side surface and the base surface of the second area.

[0017] In one possible embodiment, after the step of "using a second laser to clean the base surface of the second area", the method for making the end cover also includes: using a third laser to clean the base surface of the first area, the base surface of the second area, the base bottom surface of the third area and the base bottom surface of the fourth area.

[0018] In a possible implementation, the energy density of the second laser is smaller than the energy density of the first laser.

[0019] In a possible implementation, the energy density of the third laser is smaller than the energy density of the first laser.

[0020] In a third aspect, the present application provides an energy storage device. The energy storage device includes a shell, an electrode assembly, an electrolyte, a pole, a seal and the end cover. The shell is provided with an opening and a receiving cavity, the receiving cavity is communicated with the opening, the electrode assembly and the electrolyte are both provided in the receiving cavity, and the electrode assembly is immersed in the electrolyte. The end cover covers the opening and is fixedly connected to the shell. The pole is installed in the pole hole of the end cover and is electrically connected to the electrode assembly. The seal is provided in the injection hole and is welded and fixed to the inner wall of the injection hole.

[0021] In one possible embodiment, the seal comprises a sealing post and a sealing head, wherein the sealing head has a larger diameter than the sealing post and is axially connected to the sealing post. The sealing post is disposed within the through-hole of the injection hole, and the sealing head is disposed within the recessed groove of the injection hole, and the sealing head is welded to the inner wall of the recessed groove.

[0022] In a fourth aspect, the present application provides an electrical device, comprising the above-mentioned energy storage device, wherein the energy storage device is used to supply power to the electrical device.

[0023] In summary, the end cover provided in the present application is provided with a first sub-surface on the periphery of the liquid injection hole and a second sub-surface with a lower surface roughness on the periphery of the first sub-surface, so that the second sub-surface can reduce or even prevent the electrolyte from penetrating into the first sub-surface. When the end cover is applied to the energy storage device, the cleanliness of the welding area of ​​the seal can be improved, the welding quality between the seal and the end cover can be improved, and the sealing effect of the seal on the liquid injection hole can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained like these drawings without any creative work.

[0025] Figure 1 This is an application scenario diagram of the electrical equipment provided in the embodiment of the present application;

[0026] Figure 2 is a schematic structural diagram of the energy storage device provided in an embodiment of the present application;

[0027] Figure 3 yes Figure 2 A schematic diagram of the exploded structure of the energy storage device shown;

[0028] Figure 4 yes Figure 3 A schematic diagram of the exploded structure of the end cap assembly in the energy storage device shown;

[0029] Figure 5 yes Figure 4 A schematic diagram of a portion of the structure of the end cap in the end cap assembly shown;

[0030] Figure 6 yes Figure 5 A schematic diagram of a portion of the structure of the end cover shown at another angle;

[0031] Figure 7 yes Figure 4 A schematic diagram of a partial cross-sectional structure of an end cap in the end cap assembly shown along the AA direction;

[0032] Figure 8 yes Figure 3 A schematic diagram of a partial cross-sectional structure of an end cap assembly in the energy storage device shown along direction BB;

[0033] Figure 9It is a flow chart of the method for making the end cap provided in this application;

[0034] Figure 10 It is a partial structural diagram of the basic end cover provided in step S1.

[0035] Reference numerals: energy storage system 1000; first electric energy conversion device 200; second electric energy conversion device 210; high-voltage cable 220; energy storage device 100; end cap assembly 1; housing 30; receiving chamber 31; electrode assembly 40; pole core 41; positive electrode ear 411; negative electrode ear 412; first connecting member 51; second connecting member 52; lower plastic 60; third surface 61; fourth surface 62; third pole hole 63; fourth pole hole 64; liquid injection hole 65; vent hole 66; guide hole 67; first pole 71; second pole 72; first upper plastic 81; second upper plastic 82; explosion-proof valve 90; end cap 10; first surface 11; first subsurface Surface 111; second sub-surface 112; third sub-surface 113; second surface 12; injection hole 13; through hole 131; sink 132; side surface 133; bottom surface 134; first sub-bottom surface 1341; second sub-bottom surface 1342; first pole hole 14; second pole hole 15; explosion-proof hole 16; seal 20; sealing column 21; sealing head 22; first surface 221; second surface 222; outer peripheral surface 223; base end cover 10a; base surface 11a; first area 111a; second area 112a; fifth area 113a; base side surface 133a; base bottom surface 134a; third area 1341a; fourth area 1342a. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0037] Because the energy people need is highly temporal and spatially dependent, rationally utilizing energy and improving its efficiency requires a medium or device that can store one form of energy in the same form or convert it into another, allowing it to be released in a specific form based on future application needs. As we all know, to achieve the goal of carbon neutrality, the primary method for generating green electricity is to develop green energy sources such as photovoltaics and wind power to replace fossil fuels. Currently, green electricity generation generally relies on photovoltaics, wind power, and hydropower. However, wind and solar power are generally intermittent and volatile, leading to grid instability, insufficient power during peak hours, and excessive power during off-peak hours. Unstable voltage can also damage electricity. Therefore, insufficient electricity demand or insufficient grid capacity can lead to "wind and solar curtailment." Addressing these issues requires energy storage. That is, electrical energy is converted into other forms of energy through physical or chemical means and stored, and then the energy is converted into electrical energy and released when needed. Simply put, energy storage is like a large "power bank". When there is sufficient photovoltaic and wind energy, electrical energy is stored and the stored electricity is released when needed.

[0038] Taking electrochemical energy storage as an example, this solution provides an energy storage device with a group of chemical batteries inside. The energy storage device mainly uses the chemical elements in the chemical batteries as energy storage media. The charging and discharging process is accompanied by chemical reactions or changes in the energy storage medium. Simply put, the electricity generated by wind and solar energy is stored in the chemical batteries. When the use of external electricity reaches its peak, the stored electricity is released for use, or transferred to places where electricity is scarce for use.

[0039] Currently, energy storage (i.e., energy storage) has a wide range of application scenarios, including power generation-side energy storage, grid-side energy storage, renewable energy grid-connected energy storage, and user-side energy storage. The corresponding types of energy storage devices include:

[0040] (1) Large energy storage containers used in grid-side energy storage scenarios can serve as high-quality active and reactive power regulation power sources in the grid, achieving load matching of electricity in time and space, enhancing the ability to absorb renewable energy, and are of great significance in grid system backup, alleviating peak load power supply pressure, and peak and frequency regulation;

[0041] (2) The main operating mode of small and medium-sized energy storage cabinets used in industrial and commercial energy storage scenarios (banks, shopping malls, etc.) on the user side and small household energy storage boxes used in home energy storage scenarios on the user side is "peak shaving and valley filling". Since there is a large price difference in electricity prices at peak and valley locations according to electricity demand, after users have energy storage equipment, in order to reduce costs, they usually charge the energy storage cabinets / boxes during the low electricity price period; during the peak electricity price period, the electricity in the energy storage equipment is discharged for use to achieve the purpose of saving electricity bills. In addition, in remote areas and areas with high incidence of natural disasters such as earthquakes and hurricanes, the existence of the household energy storage device 100 is equivalent to the user providing a backup power supply for himself and the power grid, eliminating the inconvenience caused by frequent power outages due to disasters or other reasons.

[0042] See also Figure 1 , Figure 1 This is an application scenario diagram of the electrical equipment provided in the embodiment of this application. Figure 1 The embodiment is described by taking the shared energy storage scenario on the power generation / distribution side as an example, but the energy storage device 100 of the present application is not limited to the energy storage scenario on the power generation / distribution side.

[0043] The present application provides an energy storage system 1000, which includes: a high-voltage cable 220, a first power conversion device 200, a second power conversion device 210, and the energy storage device 100 provided in the present application. In some embodiments of the power generation side scenario, the second power conversion device 210 can be a wind power conversion device. Since the power generated by wind power conversion is volatile, random, and intermittent, the unstable power output by the wind power conversion device can be first stored in the energy storage device 100 by connecting to the grid. The energy storage device 100 is connected to the high-voltage cable 220 and outputs smooth power to the power consumption side of the distribution network, thereby achieving peak load and frequency regulation and stable operation of the power grid. Alternatively, the wind power conversion device is always connected to the high-voltage cable 220. Under normal power generation conditions, the electric energy output by the wind power conversion device is supplied to the power distribution network through the high-voltage cable 220. When the current power load is low and the wind power conversion device generates excess power, the excess power is first stored in the energy storage device 100, reducing the wind and solar power abandonment rates and improving the problem of new energy power generation and consumption. When the power load is high, the power grid issues an instruction to transmit the power stored in the energy storage device 100 in conjunction with the high-voltage cable 220 in a grid-connected mode to the power distribution network for use, providing peak shaving, frequency regulation, standby and other services for the power grid operation, giving full play to the peak shaving role of the power grid, promoting peak shaving and valley filling of the power grid, and alleviating the power supply pressure of the power grid.

[0044] In some embodiments on the distribution network side, the first power conversion device 200 may be a photovoltaic power conversion device. The energy storage device 100 is connected to the high-voltage cable 220 and installed downstream of the high-voltage cable 220 and between the user load. The power output by the photovoltaic power conversion device is stored in the energy storage device 100, which can promptly respond and serve as a backup power source in the event of a power grid / distribution network failure. Alternatively, it can alleviate line congestion in the high-voltage cable 220 transmission line and provide power supply support during planned power grid expansion to mitigate the economic pressure caused by power grid / distribution capacity expansion.

[0045] Optionally, the second power conversion device 210 may include, but is not limited to, a wind power conversion device, and the first power conversion device 200 may include, but is not limited to, a photovoltaic power conversion device. The first power conversion device 200 and the second power conversion device 210 may convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy, and mechanical energy into electrical energy.

[0046] Optionally, the energy storage device 100 may include but is not limited to energy storage application scenarios such as energy storage power stations, hydropower / thermal / wind power generation systems, solar power generation systems, mobile power systems, smart home systems or temporary power supply systems, and may also be used in data centers, military equipment, aerospace, charging piles, electric vehicles and other fields.

[0047] Optionally, the energy storage device 100 may include, but is not limited to, a single cell, or a battery module, battery pack, battery cluster, mobile power supply, energy storage cabinet / container, or other integrated battery system composed of single cells. The energy storage device 100 provided in the embodiments of this application may be applied in, but is not limited to, the products listed above. Other application forms are also possible. The embodiments of this application do not impose strict limitations on the application form of the energy storage device 100. The embodiments of this application illustrate the energy storage device 100 as a multi-cell battery.

[0048] Optionally, when the energy storage device 100 is a single battery, the energy storage device 100 may be, but is not limited to, at least one of a cylindrical battery, a square battery, a prismatic battery, or batteries of other shapes.

[0049] Optionally, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be recharged to activate the active material after discharge and continue to be used. The battery cell may be a lithium-ion battery, a sodium-ion battery, a sodium-lithium-ion battery, a lithium metal battery, a sodium metal battery, a lithium-sulfur battery, a magnesium-ion battery, a nickel-metal hydride battery, a nickel-cadmium battery, a lead-acid battery, or the like, and this application does not impose specific limitations on this.

[0050] See also Figure 2 and Figure 3 , Figure 2is a structural diagram of the energy storage device 100 provided in an embodiment of the present application, Figure 3 yes Figure 2 Schematic diagram of the exploded structure of the energy storage device 100 is shown.

[0051] For ease of description, in this application, the length direction of the energy storage device 100 is defined as the X direction, the width direction of the energy storage device 100 is defined as the Y direction, and the thickness direction of the energy storage device 100 is defined as the third direction. The X direction, Y direction, and Z direction are perpendicular to each other.

[0052] The energy storage device 100 includes a shell 30, an end cap assembly 1, an electrode assembly 40, an electrolyte, a first connector 51 and a second connector 52. The shell 30 is provided with a receiving chamber 31, and the opening of the receiving chamber 31 is located on one side of the shell 30 in the height direction. The electrode assembly 40 and the electrolyte are located in the receiving chamber 31, and the electrode assembly 40 is immersed in the electrolyte. The electrode assembly 40 includes a plurality of pole cores 41. The plurality of pole cores 41 are arranged side by side along the width direction (Y direction) of the energy storage device 100. The pole core 41 includes a positive electrode tab 411 and a negative electrode tab 412. The end cap 10 group is installed on the open side of the shell 30 and is fixedly connected to the shell 30 to close the receiving chamber 31. The first connector 51 is connected between the positive electrode tab 411 and the positive electrode column of the end cap assembly 1, and the second connector 52 is connected between the negative electrode tab 412 and the negative electrode column of the end cap assembly 1.

[0053] In this embodiment, the outer surface of the electrode assembly 40 is also covered with an insulating film (not shown) to protect the electrode core 41 from being scratched. The insulating film is coated on the outer surface of the electrode assembly 40, and the side of the insulating film is hot-melt bonded to the end cap assembly 1.

[0054] See also Figure 4 , Figure 4 yes Figure 3 A schematic diagram of the exploded structure of the end cover assembly 1 in the energy storage device 100 is shown.

[0055] The end cap assembly 1 includes an end cap 10, a lower plastic 60, a pole, an upper plastic, an explosion-proof valve 90 and a seal 20. In this embodiment, the end cap 10 is a rectangular thin plate. In other embodiments, the end cap 10 can also be a circular plate, an elliptical plate or other special-shaped plates. In this embodiment, the end cap 10 is a plain aluminum part. The end cap 10 includes a first surface 11 and a second surface 12. The first surface 11 and the second surface 12 are arranged opposite to each other along the thickness direction of the end cap 10, that is, they are arranged opposite to each other along the Z direction. The end cap 10 is provided with a pole hole, an explosion-proof hole 16 and an injection hole 13. The pole hole, the injection hole 13 and the explosion-proof hole 16 all pass through the first surface 11 and the second surface 12 along the Z direction. Among them, there are two pole holes. The two pole holes are the first pole hole 14 and the second pole hole 15. Along the length direction of the end cover 10 , that is, along the X direction, the first pole hole 14 , the injection hole 13 , the explosion-proof hole 16 and the second pole hole 15 are sequentially arranged at intervals.

[0056] The lower plastic 60 is roughly in the shape of a rectangular sheet. It is made of an insulating material. Exemplarily, the lower plastic 60 is made of plastic or rubber, or it can be made of other insulating materials. The lower plastic 60 includes a third surface 61 and a fourth surface 62. The third surface 61 and the fourth surface 62 are disposed opposite each other along the thickness direction of the lower plastic 60. The lower plastic 60 is provided with a third pole hole 63, a fourth pole hole 64, a liquid injection hole 65, a vent 66, and a diversion hole 67. The third pole hole 63, the fourth pole hole 64, the liquid injection hole 65, the vent 66, and the diversion hole 67 all extend through the third surface 61 and the fourth surface 62 along the thickness direction of the lower plastic 60. The third pole hole 63, the liquid injection hole 65, the vent 66, and the fourth pole hole 64 are spaced apart in sequence along the X direction. There are multiple diversion holes 67. A plurality of guide holes 67 are spaced apart in the lower plastic 60 and spaced apart from the third pole hole 63 , the injection hole 65 , the vent hole 66 and the fourth pole hole 64 .

[0057] The lower plastic 60 and the end cap 10 are stacked and fixedly connected along the Z direction. The third surface 61 faces the second surface 12. The third pole hole 63 and the first pole hole 14 are opposite each other along the Z direction. The fourth pole hole 64 and the second pole hole 15 are opposite each other along the Z direction. The liquid injection hole 65 and the liquid injection hole 13 are opposite each other along the Z direction. The vent hole 66 and the explosion-proof hole 16 are opposite each other along the Z direction.

[0058] In this embodiment, there are two poles and two upper plastics. The two poles are a first pole 71 and a second pole 72. The two upper plastics are a first upper plastic 81 and a second upper plastic 82. The first pole 71 is inserted into the first pole hole 14 and the third pole hole 63, and the first upper plastic 81 is sleeved around the outer periphery of the first pole 71. The first pole 71 is insulated from the end cap 10 by the first upper plastic 81. The second pole 72 is inserted into the second pole hole 15 and the fourth pole hole 64, and the second upper plastic 82 is sleeved around the outer periphery of the second pole 72. The second pole 72 is insulated from the end cap 10 by the second upper plastic 82. In this embodiment, the first pole 71 is a positive pole, and the second pole 72 is a negative pole. In other embodiments, the first pole 71 can also be a negative pole, and the second pole 72 can be a positive pole.

[0059] Explosion-proof valve 90 is mounted on explosion-proof hole 16 and fixedly connected to end cap 10. It is positioned opposite vent 66. Exemplarily, explosion-proof valve 90 is welded to the inner wall of explosion-proof hole 16. When the pressure inside energy storage device 100 becomes excessive, gas will pass through vent 66 and contact explosion-proof valve 90, impacting it and causing it to open and release pressure, thereby preventing explosion of energy storage device 100 and improving its safety.

[0060] The injection hole 13 and the injection through-hole 65 are used for injecting electrolyte. Specifically, during the injection process of the energy storage device 100, the electrolyte is injected into the energy storage device 100 through the injection hole 13 and the injection through-hole 65. The diversion hole 67 can guide the electrolyte entering between the lower plastic 60 and the end cap 10, increasing the injection speed and avoiding electrolyte waste. The seal 20 is provided in the injection hole 13 and is used to block the injection hole 13 to prevent the electrolyte in the energy storage device 100 from leaking through the injection hole 13.

[0061] See also Figures 5 to 7 , Figure 5 yes Figure 4 A partial structural diagram of the end cover 10 in the end cover assembly 1 is shown. Figure 6 yes Figure 5 The schematic diagram of the partial structure of the end cover 10 at another angle is shown. Figure 7 yes Figure 4 The end cover 10 in the end cover assembly 1 is shown as a partial cross-sectional structural schematic diagram along the AA direction.

[0062] The first surface 11 includes a first sub-surface 111, a second sub-surface 112, and a third sub-surface 113. The first sub-surface 111 is annular and is arranged around the outer circumference of the liquid injection hole 13. In this embodiment, the first sub-surface 111 is in the shape of a circular ring. In other embodiments, the first sub-surface 111 may also be in the shape of a square ring, an elliptical ring, or other rings. The outer diameter of the first sub-surface 111 ranges from 9 mm to 12 mm. For example, the outer diameter of the first sub-surface 111 is 12 mm.

[0063] The second sub-surface 112 is annular. The second sub-surface 112 is arranged around the outer circumference of the first sub-surface 111 and is connected to the first sub-surface 111. In this embodiment, the second sub-surface 112 is in the shape of a circular ring. In other embodiments, the second sub-surface 112 may also be in the shape of a square ring, an elliptical ring, or other rings. The inner diameter of the second sub-surface 112 ranges from 9 mm to 12 mm, and the outer diameter is greater than 9 mm and less than or equal to 20 mm. For example, the inner diameter of the second sub-surface 112 is 12 mm and the outer diameter is 14 mm.

[0064] The third sub-surface 113 is disposed around the outer periphery of the second sub-surface 112 and is connected to the second sub-surface 112. The third sub-surface 113, the second sub-surface 112 and the first sub-surface 111 together form the first surface 11.

[0065] The surface roughness of the second sub-surface 112 is less than that of the first sub-surface 111. That is, the second sub-surface 112 is smoother than the first sub-surface 111. In this embodiment, the surface roughness of the second sub-surface 112 is less than that of the third sub-surface 113. That is, the third sub-surface 113 is smoother than the first sub-surface 111.

[0066] It should be noted that the diffusion ability of liquid on the solid surface is related to the size of the contact angle. The larger the contact angle (>90°), the more hydrophobic the liquid is on the solid surface, and the slower the liquid diffuses on the solid surface; conversely, the smaller the contact angle, the more hydrophilic the liquid is on the solid surface, and the faster the liquid diffuses on the fixed surface. The size of the contact angle depends on the surface energy of the contact surface, and the surface energy is related to the surface roughness. According to Young's equation, the spreading of liquid on a smooth and uniform solid surface can be expressed by the intrinsic contact angle θ: cosθ=(γ sv -γ sl ) / γ lv Where γ sv , γ sl , γ lv The interfacial tensions of the solid-gas, solid-liquid, and liquid-gas interfaces are shown in Figure 1. It can be seen that the intrinsic contact angle on a smooth solid surface is determined by the surface energy of the solid. The higher the surface energy, the smaller the contact angle and the more hydrophilic the surface. The lower the surface energy, the larger the contact angle and the more hydrophobic the surface.

[0067] According to the Wenzel model, cosθ′=rcosθ. Here, r is the roughness factor, which describes the ratio between the actual surface and the geometric surface. The rougher the surface, the greater the ratio of the actual surface to the geometric surface, the larger the roughness factor r, the larger the contact angle, the higher the surface energy, and the more hydrophilic the surface. The smoother the surface, the smaller the ratio of the actual surface to the geometric surface, the smaller the roughness factor r, the smaller the contact angle, the lower the surface energy, and the more hydrophobic the surface. Therefore, reducing surface roughness can make the liquid more hydrophobic on a fixed surface and slow the diffusion of the liquid on a fixed surface.

[0068] It can be understood that in this embodiment, the surface energy of the second sub-surface 112 is smaller than the surface energy of the first sub-surface 111 and the surface energy of the third sub-surface 113, the hydrophobicity of the electrolyte on the second sub-surface 112 is greater than the hydrophobicity of the electrolyte on the first sub-surface 111 and the third sub-surface, the contact angle of the electrolyte with the second sub-surface 112 is smaller than the contact angle of the electrolyte with the first sub-surface 111 and the third sub-surface, and the diffusion rate of the electrolyte on the second sub-surface 112 is smaller than the diffusion rate of the electrolyte on the first sub-surface 111 and the third sub-surface.

[0069] In this embodiment, by setting the surface roughness of the second sub-surface 112 to be smaller than the surface roughness of the first surface 11 and the surface roughness of the third surface 61, the surface energy of the second sub-surface 112 can be reduced, and the diffusion rate of the electrolyte on the second sub-surface 112 can be reduced, thereby reducing or even preventing the electrolyte located on the third sub-surface 113 from penetrating into the first sub-surface 111, thereby avoiding affecting the sealing performance of the seal 20 and the injection hole 13.

[0070] Among them, the surface roughness of the first sub-surface 111 and the surface roughness of the second sub-surface 112 are formed by laser cleaning. In the actual manufacturing process, the energy density of the laser can be reduced when the laser cleaning is performed on the second sub-surface 112, so that the formed second sub-surface 112 is smoother and the surface roughness is lower. Alternatively, the number of times or time of laser cleaning on the second sub-surface 112 can be reduced to make the formed second sub-surface 112 smoother and the surface roughness is lower. In this embodiment, the first sub-surface 111 is recessed relative to the second sub-surface 112 toward the second surface 12. That is, the first sub-surface 111 is located on the side of the second sub-surface 112 close to the second surface 12. In other embodiments, the first sub-surface 111 and the second sub-surface 112 may also be flush or approximately flush. In this embodiment, the second sub-surface 112 is flush or approximately flush with the third sub-surface 113.

[0071] It should be noted that laser cleaning refers to the use of pulsed laser thermal ablation to remove oxide layers, impurities, and contaminants from the surface of aluminum alloys. Specifically, high-peak-power laser cleaning technology can release a high-energy laser beam in a very short time, generating high temperatures that quickly evaporate or remove contaminants without significantly affecting the base material.

[0072] In this embodiment, the first sub-surface 111 and the second sub-surface 112 are formed by laser cleaning, which can remove the electrolyte remaining on the first sub-surface 111 and the second sub-surface 112 during the injection process. At the same time, the oxide layer, impurities and contaminants on the first sub-surface 111 and the second sub-surface 112 can be removed, thereby improving the connection stability between the seal 20 and the end cover 10.

[0073] Please continue reading Figures 5 to 7 The injection hole 13 includes a through hole 131 and a sink 132. The through hole 131 and the sink 132 are connected along the thickness direction of the end cover 10, that is, along the Z direction, and are interconnected. One end of the through hole 131 passes through the second surface 12, and the other end is connected to the sink 132. The sink 132 is provided on the first surface 11 and is arranged around the through hole 131. It can be understood that the first sub-surface 111 is arranged around the periphery of the sink 132. In this embodiment, the through hole 131 is a circular hole, the sink 132 is a circular groove, and the diameter of the sink 132 is larger than the diameter of the through hole 131.

[0074] The sink 132 includes a side surface 133 and a bottom surface 134. The bottom surface 134 is arranged around the liquid injection hole 13, and the side surface 133 is arranged perpendicular to the bottom surface 134 and connected between the bottom surface 134 and the first sub-surface 111. The bottom surface 134 includes a first sub-bottom surface 1341 and a second sub-bottom surface 1342. The second sub-bottom surface 1342 is annular and is arranged around the outer circumference of the through hole 131, and the second sub-bottom surface 1342 is connected to the side wall of the through hole 131. In this embodiment, the second sub-bottom surface 1342 is annular. The inner diameter of the second sub-bottom surface 1342 is greater than or equal to 3 mm and less than 7 mm, and the outer diameter ranges from 5 mm to 7 mm. Exemplarily, the inner diameter of the second sub-bottom surface 1342 is 4.4 mm and the outer diameter is 5 mm. In other embodiments, the second sub-bottom surface 1342 may also be in the shape of a square ring, an elliptical ring, or other rings.

[0075] The first sub-bottom surface 1341 is annular. The first sub-bottom surface 1341 is arranged around the outer circumference of the second sub-bottom surface 1342 and is connected between the second sub-bottom surface 1342 and the side surface 133. In this embodiment, the first sub-bottom surface 1341 is annular. The inner diameter of the first sub-bottom surface 1341 ranges from 5 mm to 7 mm. Exemplarily, the inner diameter of the first sub-bottom surface 1341 is 5 mm. In other embodiments, the first sub-bottom surface 1341 may also be in the shape of a square ring, an elliptical ring, or other rings. It can be understood that the first sub-bottom surface 1341 and the second sub-bottom surface 1342 together form the bottom surface 134, that is, together form the bottom wall of the sink 132.

[0076] The surface roughness of the second sub-bottom surface 1342 is less than that of the first sub-bottom surface 1341. That is, compared to the first sub-bottom surface 1341, the second sub-bottom surface 1342 is smoother. In other words, the surface energy of the second sub-bottom surface 1342 is less than the surface energy of the first sub-bottom surface 1341, the hydrophobicity of the electrolyte on the second sub-bottom surface 1342 is greater than the hydrophobicity of the electrolyte on the first sub-bottom surface 1341, and the contact angle between the electrolyte and the second sub-bottom surface 1342 is less than the contact angle between the electrolyte and the first sub-bottom surface 1341. In other words, the diffusion rate of the electrolyte on the second sub-bottom surface 1342 is less than the diffusion rate of the electrolyte on the first sub-bottom surface 1341.

[0077] In this embodiment, by setting the surface roughness of the second sub-bottom surface 1342 to be smaller than the surface roughness of the first sub-bottom surface 1341, the surface energy of the second sub-bottom surface 1342 can be reduced, and the diffusion rate of the electrolyte in the second sub-bottom surface 1342 can be reduced, thereby reducing or even preventing the electrolyte from penetrating from the through hole 131 through the second sub-bottom surface 1342 into the first sub-bottom surface 1341, thereby further avoiding affecting the sealing performance of the seal 20 and the injection hole 13.

[0078] Among them, the surface roughness of the second sub-bottom surface 1342 and the surface roughness of the first sub-bottom surface 1341 are formed by laser cleaning. In the actual manufacturing process, the energy density of the laser can be reduced when the laser cleaning is performed on the second sub-bottom surface 1342, so that the formed second sub-bottom surface 1342 is smoother and the surface roughness is lower. Alternatively, the number of times or time of laser cleaning on the second sub-bottom surface 1342 can be reduced to make the formed second sub-bottom surface 1342 smoother and the surface roughness is lower. In this embodiment, the first sub-bottom surface 1341 is recessed relative to the second sub-bottom surface 1342 toward the second surface 12. That is, the first sub-bottom surface 1341 is located on the side of the second sub-bottom surface 1342 close to the second surface 12. In other embodiments, the second sub-bottom surface 1342 and the first sub-bottom surface 1341 can also be flush or approximately flush.

[0079] In this embodiment, the surface roughness of the first sub-bottom surface 1341 is the same as the surface roughness of the first sub-surface 111. During the actual manufacturing process, the areas corresponding to the first sub-bottom surface 1341 and the first sub-surface 111 can be cleaned simultaneously to simplify the cleaning process of the end cap 10. In other embodiments, the surface roughness of the first sub-bottom surface 1341 and the surface roughness of the first sub-surface 111 can also be different.

[0080] In this embodiment, the surface roughness of the second sub-bottom surface 1342 is the same as the surface roughness of the second sub-surface 112. During the actual manufacturing process, the areas corresponding to the second sub-bottom surface 1342 and the second sub-surface 112 can be cleaned simultaneously to simplify the cleaning process of the end cap 10. In other embodiments, the surface roughness of the second sub-bottom surface 1342 and the surface roughness of the second sub-surface 112 can also be different.

[0081] In this embodiment, the surface roughness of the side surface 133 is consistent with or approximately the same as the roughness of the first sub-bottom surface 1341. That is, the surface roughness of the side surface 133, the roughness of the first sub-bottom surface 1341, and the surface roughness of the first sub-surface 111 are all the same. In the actual manufacturing process, the corresponding areas of the side surface 133, the first sub-bottom surface 1341, and the first sub-surface 111 can be cleaned simultaneously to ensure that the surface roughness of the side surface 133, the first sub-bottom surface 1341, and the first sub-surface 111 are consistent. It is understood that the surface roughness of the second sub-bottom surface 1342 is simultaneously less than the surface roughness of the first sub-bottom surface 1341 and the surface roughness of the side surface 133.

[0082] In this embodiment, by laser cleaning the bottom surface 134 and the side surface 133 of the sink 132, the electrolyte remaining on the bottom surface 134 and the side surface 133 during the injection process can be removed. At the same time, the oxide layer, impurities and contaminants on the bottom surface 134 and the side surface 133 can be removed, thereby improving the connection stability between the seal 20 and the end cover 10.

[0083] Please combine Figure 4 and Figure 8 , Figure 8 yes Figure 3 The schematic diagram of the partial cross-section structure of the end cover assembly 1 in the energy storage device 100 along the BB direction is shown.

[0084] The structure of the seal 20 is compatible with the structure of the liquid injection hole 13. This compatibility means that the seal 20 can be installed in the liquid injection hole 13 to block the liquid injection hole 13. Specifically, the seal 20 includes a sealing post 21 and a sealing head 22. The structure of the sealing head 22 is compatible with the structure of the sink 132, and the structure of the sealing post 21 is compatible with the structure of the through hole 131.

[0085] In this embodiment, the sealing head 22 is disc-shaped. The diameter of the sealing head 22 is slightly smaller than or equal to the inner diameter of the recess 132, allowing the sealing head 22 to fit within the recess 132. The sealing head 22 includes a first surface 221 and an outer peripheral surface 223 of a second surface 222. The first surface 221 and the second surface 222 are disposed opposite each other along the axial direction of the sealing head 22. The outer peripheral surface 223 surrounds the outer circumference of the sealing head 22 and is connected to the first surface 221 and the second surface 222.

[0086] In this embodiment, the sealing post 21 is cylindrical. The diameter of the sealing post 21 is slightly smaller than or equal to the diameter of the through hole 131, so that the sealing post 21 can be disposed within the through hole 131. The sealing post 21 is connected to the sealing head 22 along the length of the sealing member 20. Specifically, the sealing post 21 is connected to the first surface 221 of the sealing head 22 and is located in the middle area of ​​the first surface 221. The axis of the sealing post 21 coincides with or substantially coincides with the axis of the sealing head 22.

[0087] In this embodiment, the sealing member 20 is a sealing pin, and the material of the sealing member 20 is metal. The sealing member 20 is fixed to the injection hole 13 by welding. Among them, the sealing column 21 is located in the through hole 131, and the sealing head 22 is located in the sink 132. The sealing head 22 is fixedly connected to the inner wall of the sink 132 by welding. In this embodiment, the outer peripheral surface 223 of the sealing head 22 is welded and fixed to the side surface 133 of the sink 132, and the first surface 221 of the sealing head 22 is welded and fixed to the bottom surface 134 of the sink 132. In other embodiments, the outer peripheral surface 223 of the sealing head 22 is welded and fixed to the side surface 133 of the sink 132, and the first surface 221 of the sealing head 22 is partially welded to the bottom surface 134 of the sink 132, or not welded. The outer peripheral surface of the sealing column 21 and the inner wall surface of the through hole 131 may be welded or not welded.

[0088] During the actual welding process, liquid solder can be injected along the outer periphery of the sealing head 22 and into the gap between the sealing head 22 and the side surface 133 of the sink 132, so that the liquid solder flows along the side surface 133 of the sink 132. After the liquid solder solidifies, the outer periphery 223 and the side surface 133 are welded and fixed.

[0089] In some embodiments, the liquid solder may also flow along the side surface 133 of the sink 132 to the bottom surface 134 . After the liquid solder solidifies, the outer peripheral surface 223 is welded to the side surface 133 , and the bottom surface 134 is welded to the first surface 221 .

[0090] In one embodiment, the liquid solder also flows along the bottom surface 134 to the inner wall of the through hole 131. After the liquid solder solidifies, the outer peripheral surface 223 is welded to the side surface 133, the bottom surface 134 is welded to the first surface 221, and the inner wall of the through hole 131 is welded to the outer peripheral surface of the sealing column 21. This improves the connection stability between the sealing member 20 and the end cap 10 and enhances the sealing effect of the sealing member 20 on the liquid injection hole 13.

[0091] In this embodiment, a recess 132 is provided in the injection hole 13, and a sealing pin is provided correspondingly in the seal 20, so that the bottom surface 134 of the recess 132 can limit the seal 20 in the thickness direction of the end cover 10, thereby improving the connection stability between the seal 20 and the end cover 10 and improving the sealing effect of the seal 20 on the injection hole 13.

[0092] It is understandable that the first sub-surface 111, the side surface 133 and the first sub-bottom surface 1341 are the welding areas of the seal 20. When there is electrolyte, or contaminants such as oxide layer, impurities, etc. in the welding area, it will lead to poor welding effect between the seal 20 and the inner wall of the injection hole 13. In this embodiment, by cleaning the first sub-surface 111, the side surface 133 and the first sub-bottom surface 1341 to remove the electrolyte, oxide layer, impurities and other contaminants remaining on the first sub-surface 111, the side surface 133 and the first sub-bottom surface 1341, the cleanliness of the welding area of ​​the seal 20 can be improved, thereby improving the welding quality of the seal 20 and the end cover 10, and improving the sealing effect of the seal 20 on the injection hole 13. At the same time, in this embodiment, by cleaning the first sub-surface 111, the side surface 133 and the first sub-bottom surface 1341, the surface roughness of the first sub-surface 111, the side surface 133 and the first sub-bottom surface 1341 can be improved, thereby improving the bonding force between the solder and the first sub-surface 111, the side surface 133 and the first sub-bottom surface 1341, and further improving the welding stability between the seal 20 and the end cover 10.

[0093] In this embodiment, by setting a second sub-surface 112 with a lower surface roughness on the periphery of the welding area, that is, setting the second sub-surface 112 on the periphery of the first sub-surface 111, the electrolyte located on the third sub-surface 113 can be reduced or even prevented from penetrating into the first sub-surface 111, that is, the electrolyte located on the third sub-surface 113 can be reduced or even prevented from penetrating into the welding area, thereby further improving the cleanliness of the welding area, and then improving the welding quality of the seal 20 and the end cover 10, avoiding the electrolyte penetrating into the welding area to affect the welding stability of the seal 20, and avoiding the seal 20 to affect the sealing performance of the injection hole 13.

[0094] At the same time, in this embodiment, by providing a second sub-bottom surface 1342 with a lower surface roughness on the inner periphery of the welding area, that is, providing the second sub-bottom surface 1342 on the inner periphery of the first sub-bottom surface 1341, the electrolyte can be reduced or even prevented from penetrating from the through hole 131 through the second sub-bottom surface 1342 into the first sub-bottom surface 1341, that is, the electrolyte can be reduced or even prevented from penetrating from the through hole 131 through the second sub-bottom surface 1342 into the welding area, thereby further avoiding affecting the welding stability of the seal 20 and avoiding affecting the sealing performance of the injection hole 13 by the seal 20.

[0095] See also Figure 9 , Figure 9 It is a flow chart of the method for manufacturing the end cover 10 provided in this application. Figure 9 The production method shown is used to produce Figure 2 The end cap 10 in the energy storage device 100 is shown.

[0096] The manufacturing method of the end cap 10 includes:

[0097] S1: Providing a base end cap 10a, wherein the base end cap 10a is provided with a liquid injection hole 13, which penetrates the base end cap 10a along the thickness direction of the base end cap 10a; the base end cap 10a includes a base surface 11a, and the base surface 11a includes a first area 111a and a second area 112a. The first area 111a is provided around the periphery of the liquid injection hole 13, and the second area 112a is provided around the periphery of the first area 111a.

[0098] S2: Cleaning the base surface 11a of the first region 111a using a first laser to form a first sub-surface 111;

[0099] S3: using a second laser to clean the base surface 11a of the second region 112a to form a second sub-surface 112 , thereby obtaining the end cap 10 ; wherein the surface roughness of the second sub-surface 112 is less than that of the first sub-surface 111 .

[0100] See also Figure 10 , Figure 10 It is a partial structural diagram of the basic end cover 10a provided in step S1.

[0101] In step S1, the first region 111a is annular. Specifically, the first region 111a is an annular ring. The outer diameter of the first region 111a is 9 mm to 12 mm. The second region 112a is annular. Specifically, the second region 112a is an annular ring. The second region 112a is disposed around the first region 111a and is connected to the first region 111a. The outer diameter of the second region 112a is greater than 9 mm and less than or equal to 20 mm.

[0102] The base surface 11a further includes a fifth region 113a. The fifth region 113a is located outside the second region 112a. It is understood that the base surface 11a of the first region 111a, the base surface 11a of the second region 112a, and the base surface 11a of the fifth region 113a together form the base surface 11a.

[0103] The injection port 13 includes a through-hole 131 and a recessed groove 132. The through-hole 131 and recessed groove 132 are connected and interconnected along the thickness direction of the base end cap 10a, that is, along the Z-direction. The recessed groove 132 is provided on the base surface 11a and surrounds the through-hole 131. It will be appreciated that the first region 111a surrounds the outer periphery of the recessed groove 132. In this embodiment, the through-hole 131 is a circular hole, and the recessed groove 132 is a circular groove. The diameter of the recessed groove 132 is larger than that of the through-hole 131.

[0104] The sink 132 includes a base side surface 133a and a base bottom surface 134a. The base bottom surface 134a is arranged around the liquid injection hole 13, and the base side surface 133a is arranged perpendicular to the base bottom surface 134a. The base bottom surface 134a includes a third area 1341a and a fourth area 1342a. The fourth area 1342a is annular and arranged around the outer periphery of the through hole 131. The third area 1341a is arranged around the outer periphery of the fourth area 1342a, and the base side surface 133a is connected between the base bottom surface 134a and the base surface 11a. The outer diameter of the fourth area 1342a is 5 mm to 7 mm, and the inner diameter is greater than or equal to 3 mm and less than 7 mm. The inner diameter of the third area 1341a is 5 mm to 7 mm. It can be understood that the base bottom surface 134a of the third area 1341a and the base bottom surface 134a of the fourth area 1342a together form the base bottom surface 134a.

[0105] Please combine Figure 5 and Figure 10 In step S2, the base surface 11a of the first region 111a is cleaned using a first laser beam to remove the oxide layer, impurities, and contaminants on the surface of the base surface 11a of the first region 111a, thereby improving the weld stability between the seal 20 and the end cap 10 and the sealing effect of the seal 20 on the injection hole 13. In this embodiment, the base surface 11a of the first region 111a is cleaned using the first laser beam twice to improve the removal of the oxide layer, impurities, and contaminants on the surface of the base surface 11a of the first region 111a, further improving the weld stability between the seal 20 and the end cap 10.

[0106] Step S2 includes:

[0107] (1) Using a first laser to clean the base surface 11a of the first region 111a to form a first sub-surface 111

[0108] (2) Cleaning the base bottom surface 134a of the third region 1341a using a first laser to form a first sub-bottom surface 1341;

[0109] (3) The base side surface 133 a is cleaned using a first laser to obtain the side surface 133 .

[0110] The cleaning areas of steps (1) to (3) collectively form a first cleaning area. That is, the first area 111a, the area where the base side surface 133a is located, and the third area 1341a collectively form the first cleaning area. In this embodiment, the first cleaning area is annular. The inner diameter of the first cleaning area is 5 mm to 7 mm, and the outer diameter is 9 mm to 12 mm. For example, the inner diameter of the first cleaning area is 5 mm, and the outer diameter is 12 mm.

[0111] In the actual cleaning process, the first laser can be used to clean from the inner circle of the first cleaning area to the outer circle of the first cleaning area. Alternatively, the first laser can be used to clean from the outer circle of the first cleaning area to the inner circle of the first cleaning area.

[0112] Alternatively, a first laser may be used to simultaneously clean the base surface 11a, the base side surface 133a of the first region 111a, and the base bottom surface 134a of the third region 1341a to form a first sub-surface 111 in the first region 111a, a side surface 133 on the base side surface 133a, and a first sub-bottom surface 1341 in the third region 1341a.

[0113] In this embodiment, the surface roughness of the first sub-surface 111, the surface roughness of the side surface 133, and the surface roughness of the first sub-bottom surface 1341 are all the same. In other embodiments, the surface roughness of the first sub-surface 111, the surface roughness of the side surface 133, and the surface roughness of the first sub-bottom surface 1341 may be partially the same or all different.

[0114] As previously described, when the seal 20 is positioned in the liquid injection hole 13 and welded to the end cap 10, the first sub-surface 111, the side surface 133, and the first sub-bottom surface 1341 collectively form the welding region of the seal 20. In this embodiment, by cleaning the base surface 11a, the base side surface 133a of the first region 111a, and the base bottom surface 134a of the third region 1341a to remove oxide layers, impurities, and contaminants located on the base surface 11a, the base side surface 133a, and the base bottom surface 134a of the third region 1341a, the weld stability of the seal 20 and the end cap 10 can be improved. Moreover, in this embodiment, by cleaning the base surface 11a of the first area 111a, the base side surface 133a and the base bottom surface 134a of the third area 1341a, the surface roughness of the first sub-surface 111, the side surface 133 and the first sub-bottom surface 1341 can be improved, thereby improving the bonding force between the solder and the first sub-surface 111, the side surface 133 and the first sub-bottom surface 1341, and further improving the welding stability between the seal 20 and the end cover 10.

[0115] In step S3, the energy density of the second laser is lower than the energy density of the first laser. Specifically, the second laser is a low-energy-density laser. In this embodiment, the base surface 11a of the second region 112a is cleaned by a second laser with low energy density, which can make the base surface 11a of the second region 112a clean and smooth, reduce the surface energy of the formed second sub-surface 112, reduce the contact angle between the electrolyte and the second sub-surface 112, and slow down the diffusion rate of the electrolyte in the second sub-surface 112, thereby reducing or even preventing the electrolyte on the base surface 11a located in the fifth region 113a from penetrating into the first sub-surface 111 through the second sub-surface 112, improving the cleanliness of the welding area of ​​the seal 20, thereby improving the welding quality between the seal 20 and the end cover 10, and improving the sealing effect of the seal 20 on the injection hole 13.

[0116] At the same time, in this embodiment, by using a second laser with low energy density to clean the base surface 11a of the second area 112a, a second sub-surface 112 with lower surface roughness can be obtained to prevent the electrolyte from penetrating into the first sub-surface 111, which can simplify the manufacturing method of the end cover 10 and reduce the manufacturing cost of the end cover 10.

[0117] In this embodiment, the surface roughness of the second sub-surface 112 is smaller than the surface roughness of the base surface 11 a located in the fifth region 113 a.

[0118] In one embodiment, step S3 includes:

[0119] (a) using a second laser to clean the base surface 11a in the second region 112a to form a second sub-surface 112;

[0120] (b) The base bottom surface 134 a of the fourth region 1342 a is cleaned with a second laser to form a second sub-bottom surface 1342 .

[0121] That is, step S3 includes: using a second laser to clean the base surface 11a of the second area 112a and the base bottom surface 134a of the fourth area 1342a to form a second sub-surface 112 in the second area 112a and a second sub-bottom surface 1342 in the fourth area 1342a.

[0122] Wherein, step (a) and step (b) can be performed separately or simultaneously. When step S2 is performed simultaneously with step (2), while the second laser is used to clean the base surface 11a of the second region 112a, the second laser also cleans the base bottom surface 134a of the fourth region 1342a. In other words, the second laser is used to simultaneously clean the base surface 11a of the second region 112a and the base bottom surface 134a of the fourth region 1342a, so as to form the second sub-surface 112 in the second region 112a and the second sub-bottom surface 1342 in the fourth region 1342a.

[0123] Because the second laser is a low-energy-density laser, in this embodiment, after the second laser is used to clean the base bottom surface 134a of the fourth region 1342a, the resulting second sub-bottom surface 1342 is relatively smooth. It is understood that the surface roughness of the second sub-bottom surface 1342 is less than the surface roughness of the first sub-bottom surface 1341.

[0124] In this embodiment, the surface roughness of the second sub-bottom surface 1342 is the same as the surface roughness of the second sub-surface 112. In other embodiments, the surface roughness of the second sub-bottom surface 1342 and the surface roughness of the second sub-surface 112 may also be different.

[0125] In this embodiment, a low-energy-density second laser is used to clean the base bottom surface 134a of the fourth region 1342a, so that the base bottom surface 134a of the fourth region 1342a can be cleaned and made smooth, thereby reducing the surface energy of the obtained second sub-bottom surface 1342, reducing the contact angle between the electrolyte and the second sub-bottom surface 1342, and slowing down the diffusion rate of the electrolyte in the second sub-bottom surface 1342, thereby reducing or even preventing the electrolyte from penetrating from the through hole 131 through the second sub-bottom surface 1342 into the first sub-bottom surface 1341, thereby further avoiding affecting the sealing performance of the seal 20 and the injection hole 13.

[0126] In one embodiment, step S3 further includes:

[0127] (c) The base surface 11 a and the base side surface 133 a of the first region 111 a and the base bottom surface 134 a of the third region 1341 a are cleaned using a second laser.

[0128] That is, step S3 includes: using a second laser to clean the base surface 11a of the second area 112a, the base bottom surface 134a of the fourth area 1342a, the base surface 11a of the first area 111a, the base side surface 133a and the base bottom surface 134a of the third area 1341a to form a second sub-surface 112 in the second area 112a and a second sub-bottom surface 1342 in the fourth area 1342a.

[0129] The first area 111a, the second area 112a, the third area 1341a, the fourth area 1342a, and the area where the base side surface 133a is located together form a second cleaning area. The second cleaning area is annular and covers the first cleaning area. The inner diameter of the second cleaning area is greater than or equal to 3 mm and less than 7 mm, and the outer diameter ranges from 9 mm to 20 mm. For example, the inner diameter of the second cleaning area is 4.4 mm and the outer diameter is 14 mm. In this embodiment, the first area 111a, the second area 112a, the third area 1341a and the fourth area 1342a are cleaned at the same time, so that the cleaning area forms a circular ring, which can simplify the cleaning process. At the same time, the base surface 11a, the base side surface 133a of the first area 111a and the base bottom surface 134a of the third area 1341a can be further cleaned to further remove stains on the first sub-surface 111, the side surface 133 and the first sub-bottom surface 1341, and further increase the surface roughness of the first sub-surface 111 and the first sub-bottom surface 1341.

[0130] The method for manufacturing the end cap 10 further includes:

[0131] After step S3, a third laser is used to clean the base surface 11a of the first region 111a and the base surface 11a of the second region 112a. The third laser is a low-energy-density laser. The energy density of the third laser can be the same as or different from that of the second laser.

[0132] It should be noted that, in step S2 , due to the high energy density of the first laser, the first sub-surface 111 and the first sub-bottom surface 1341 may be oxidized and turn black.

[0133] In this embodiment, by further cleaning the base surface 11a of the first region 111a, the oxide layer formed on the base surface 11a of the first region 111a during step S2 can be removed, thereby improving the blackening of the base surface 11a of the first region 111a caused by oxidation. The electrolyte that evaporated to the base surface 11a of the first region 111a during step S3 can also be removed, thereby improving the cleanliness of the first sub-surface 111. Furthermore, in this embodiment, by further cleaning the base surface 11a of the second region 112a, contaminants such as oxides and oil stains on the base surface 11a of the second region 112a can be further removed, thereby improving the cleanliness of the second sub-surface 112.

[0134] In one embodiment, the method for manufacturing the end cap 10 further includes:

[0135] After step S3, a third laser is used to clean the base surface 11a of the first and second regions 111a, 112a, the base bottom surface 134a of the third and fourth regions 1341a, 1342a, and the base side surface 133a. The third laser is a low-energy-density laser. The energy density of the third laser can be the same as or different from that of the second laser.

[0136] In this embodiment, by further cleaning the base surface 11a, the base side surface 133a and the base bottom surface 134a of the first area 111a, the oxide layer formed on the base surface 11a, the base bottom surface 134a and the base side surface 133a of the third area 1341a during step S2 can be removed, thereby improving the blackening of the base surface 11a, the base side surface 133a and the base bottom surface 134a of the first area 111a, the base side surface 133a and the base bottom surface 134a of the third area 1341a due to oxidation. At the same time, the electrolyte volatilized to the base surface 11a, the base side surface 133a and the base bottom surface 134a of the first area 111a, the base side surface 133a and the base bottom surface 134a of the third area 1341a in step S3 can also be removed, that is, the electrolyte volatilized to the welding area is removed, thereby improving the welding quality of the seal 20 and the end cover 10.

[0137] Moreover, in this embodiment, by further cleaning the base surface 11a of the second region 112a and the base bottom surface 134a of the fourth region 1342a, oxides, oil stains and other pollutants on the base surface 11a of the second region 112a and the base bottom surface 134a of the fourth region 1342a can be further removed, thereby improving the cleanliness of the second sub-surface 112 and the second sub-bottom surface 1342.

[0138] It should be noted that the structure obtained in this embodiment is similar to Figure 5The structure of the end cap 10 shown is the same or similar. The surface formed on the base surface 11a of the first region 111a is the first sub-surface 111, the surface formed on the base surface 11a of the second region 112a is the second sub-surface 112, and the surface formed on the base surface 11a of the fifth region 113a is the third sub-surface 113. The first sub-surface 111, the second sub-surface 112, and the third sub-surface 113 collectively form the first surface 11 of the end cap 10. The surface formed on the base bottom surface 134a of the third region 1341a is the first sub-bottom surface 1341, and the surface formed on the base bottom surface 134a of the fourth region 1342a is the second sub-bottom surface 1342. The first sub-bottom surface 1341 and the second sub-bottom surface 1342 collectively form the bottom surface 134 of the sink 132. The surface formed on the base side surface 133a is the side surface 133.

[0139] The above is a detailed introduction to the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for those skilled in the art, according to the idea of ​​the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. An end cap, applied to an energy storage device, characterized in that: include: a first surface and a second surface, the first surface and the second surface being arranged opposite to each other in a thickness direction of the end cover; the end cover being provided with an injection hole, the injection hole penetrating the first surface and the second surface in the thickness direction of the end cover, the injection hole being used to inject electrolyte into the interior of the energy storage device; The first surface includes a first sub-surface, a second sub-surface, and a third sub-surface, wherein the first sub-surface is arranged around the periphery of the liquid injection hole; the second sub-surface is arranged around the periphery of the first sub-surface and connected to the first sub-surface; and the third sub-surface is arranged around the periphery of the second sub-surface and connected to the second sub-surface; The surface roughness of the second sub-surface is smaller than the surface roughness of the first sub-surface and the surface roughness of the third sub-surface.

2. The end cap according to claim 1, wherein: The injection hole includes a through hole and a sink, the through hole and the sink are connected and communicated along the thickness direction of the end cover, and the sink passes through the first surface at one end of the sink facing away from the through hole; The inner wall surface of the sink includes a bottom surface and a side surface, the side surface is arranged around the outer periphery of the through hole, and the side surface is connected between the bottom surface and the first sub-surface; the bottom surface includes a first sub-bottom surface and a second sub-bottom surface, the second sub-bottom surface is arranged around the outer periphery of the through hole and connected to the side wall surface of the through hole; the first sub-bottom surface is arranged around the outer periphery of the second sub-bottom surface and connected to the second sub-bottom surface; the surface roughness of the second sub-bottom surface is smaller than the surface roughness of the first sub-bottom surface and the surface roughness of the side surface.

3. The end cap according to claim 2, wherein: The surface roughness of the second sub-bottom surface is the same as the surface roughness of the second sub-surface.

4. The end cap according to claim 2 or 3, characterized in that: The surface roughness of the first sub-bottom surface, the surface roughness of the first sub-surface, and the surface roughness of the side surface are all the same.

5. A method for manufacturing an end cap, characterized in that: include: Providing a basic end cover, wherein the basic end cover is provided with a liquid injection hole, and the liquid injection hole penetrates the basic end cover along the thickness direction of the basic end cover; The base end cap includes a base surface, the base surface includes a first area and a second area, the first area is arranged around the periphery of the liquid injection hole, and the second area is arranged around the periphery of the first area; the base surface also includes a third sub-surface, the third sub-surface is arranged around the periphery of the second area; Cleaning the base surface of the first area using a first laser to form a first sub-surface; Cleaning the base surface of the second region using a second laser to form a second sub-surface, thereby obtaining an end cap; The surface roughness of the second sub-surface is smaller than the surface roughness of the first sub-surface and the surface roughness of the third sub-surface.

6. The method for manufacturing the end cap according to claim 5, characterized in that: The liquid injection hole includes a through hole and a sink, the through hole and the sink are connected and communicated along the thickness direction of the base end cover, and the end of the sink facing away from the through hole passes through the base surface; the sink includes a base bottom surface and a base side surface, the base side surface is arranged around the outer periphery of the through hole, and the base side surface is connected between the base surface and the base bottom surface, the base bottom surface includes a third area and a fourth area, the fourth area is arranged around the outer periphery of the through hole, and the base bottom surface of the fourth area is connected to the side wall surface of the through hole; the third area is arranged around the outer periphery of the fourth area, and the base bottom surface of the third area is connected to the base bottom surface of the fourth area; The step of "cleaning the base surface of the first region using a first laser to form a first sub-surface" further includes: cleaning the base bottom surface of the third region using a first laser to obtain a first sub-bottom surface; The base side surface is cleaned by using a first laser to obtain a side surface.

7. The method for manufacturing the end cap according to claim 6, characterized in that: The step of "using a second laser to clean the base surface of the second area to form a second sub-surface" also includes: using a second laser to clean the base bottom surface of the fourth area to obtain a second sub-bottom surface; wherein the surface roughness of the second sub-bottom surface is less than the surface roughness of the first sub-bottom surface and the surface roughness of the side surface.

8. The method for manufacturing the end cap according to claim 7, characterized in that: The step of “using a second laser to clean the base surface of the second region to form a second sub-surface” further includes: using a second laser to clean the base surface of the first region, the base side surface and the base bottom surface of the third region.

9. The method for manufacturing the end cap according to claim 5, characterized in that: After the step of "using a second laser to clean the base surface of the second area", the method for manufacturing the end cap further includes: A third laser is used to clean the base surface of the first area and the base surface of the second area.

10. The method for manufacturing the end cap according to claim 8, characterized in that: After the step of "using a second laser to clean the base surface of the second area", the method for manufacturing the end cap further includes: A third laser is used to clean the base surface of the first region, the base surface of the second region, the base side surface, the base bottom surface of the third region, and the base bottom surface of the fourth region.

11. The method for manufacturing an end cap according to any one of claims 5 to 8, characterized in that: The energy density of the second laser light is lower than the energy density of the first laser light.

12. The method for manufacturing the end cap according to claim 9 or 10, characterized in that: The energy density of the third laser light is lower than the energy density of the first laser light.

13. An energy storage device, characterized in that: comprising a shell, an electrode assembly, an electrolyte, a pole, a seal, and the end cap according to any one of claims 1 to 4; The housing has an opening and a receiving cavity, the receiving cavity is in communication with the opening, the electrode assembly and the electrolyte are both disposed in the receiving cavity, and the electrode assembly is immersed in the electrolyte; the end cap covers the opening and is fixedly connected to the housing; The pole is installed in the pole hole of the end cover and is electrically connected to the electrode assembly; the sealing member is provided in the liquid injection hole and is fixed to the inner wall of the liquid injection hole by welding.

14. The energy storage device according to claim 13, characterized in that The sealing member includes a sealing column and a sealing head, the diameter of the sealing head is larger than the diameter of the sealing column, and the sealing head and the sealing column are connected axially to the sealing member; the sealing column is arranged in the through hole of the injection hole, and the sealing head is arranged in the sink groove of the injection hole, and the sealing head is welded and fixed to the inner wall of the sink groove.

15. An electrical device, characterized in that: It includes the energy storage device as described in claim 13 or 14, and the energy storage device is used to supply power to the electrical equipment.

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