End cover assembly, energy storage device and power supply system

Abstract

The invention discloses an end cover assembly, an energy storage device and a power supply system, and relates to the technical field of energy storage. The end cover assembly comprises a cover plate and an anti-explosion valve, the cover plate is provided with a through anti-explosion hole and a pole hole, the anti-explosion valve is welded in the anti-explosion hole, and a welding mark is formed on the edge of the hole opening; the first insulating coating is located on the first surface side of the cover plate and comprises a first coating part and a second coating part, the first coating part covers the first surface of the cover plate and extends to the outer edge of the welding mark and the hole opening edge of the pole hole, the second coating part covers the welding mark, and the thickness of the second coating part is larger than that of the first coating part; and the electrode terminal penetrates through and is limited in the pole hole. According to the embodiment of the invention, the first insulating coating replaces the lower plastic, so that the risk of fire when the energy storage device is in thermal runaway is avoided; in addition, due to the fact that the second coating part is thick, the coating effect on welding slag and the like at the welding mark is facilitated, and the insulation effect between the cover plate and the electrode assembly is further improved.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to an end cover assembly, an energy storage device, and a power supply system. Background Art

[0002] Rechargeable batteries, also known as rechargeable batteries or storage batteries, are batteries that can be recharged after discharge to reactivate their active materials and continue to be used. Their recyclable nature has made them a key source of power for electrical devices. As demand for rechargeable batteries grows, so too are the demands placed on their performance, particularly their lifespan.

[0003] In related technologies, secondary batteries typically consist of an end cap assembly, an electrode assembly, and a casing. The actual production process involves separately manufacturing the end cap assembly, electrode assembly, and casing. Metal adapters are then used to weld the electrode posts and tabs of the end cap assembly to each other. The electrode assembly is then placed within the casing, and the opening of the casing is sealed with the end cap assembly before being welded together to form the basic structure of the secondary battery.

[0004] The end cap assembly consists of a plain aluminum sheet, a lower plastic, and an explosion-proof valve. The explosion-proof valve is fixed to the explosion-proof hole in the plain aluminum sheet. The lower plastic is located on the side of the plain aluminum sheet facing the electrode assembly and has a vent directly opposite the explosion-proof valve. This allows the gas to escape smoothly if the explosion-proof valve explodes due to rapid gas production from the secondary battery, such as overcharging or overheating.

[0005] However, when a secondary battery experiences thermal runaway, the high temperature environment can cause the lower plastic to melt and accumulate at the explosion-proof hole driven by the airflow. At this time, the molten aluminum beads in the secondary battery will also be ejected through the explosion-proof hole with the airflow. The high-temperature aluminum beads can easily ignite the molten lower plastic, thereby posing a risk of fire when the gas is ejected from the explosion-proof valve. Summary of the Invention

[0006] A main purpose of the present application is to provide an end cover assembly, an energy storage device and a power supply system that can reduce the risk of fire.

[0007] To achieve the above application objectives, this application adopts the following technical solutions:

[0008] According to one aspect of the present application, an end cap assembly is provided, comprising: a cover plate assembly, comprising a cover plate and an explosion-proof valve, the cover plate having a first surface and a second surface opposite to each other in a thickness direction, and an explosion-proof hole and a pole hole extending from the first surface to the second surface, the explosion-proof valve being welded in the explosion-proof hole, and forming an annular weld mark at the edge of the hole opening of the explosion-proof hole on the first surface; a first insulating coating, located on the first surface side of the cover plate, and comprising a first coating portion and a second coating portion, the first coating portion covering the first surface of the cover plate and extending to the outer edge of the weld mark and the hole opening edge of the pole hole on the first surface, the second coating portion covering the weld mark, and the thickness of the second coating portion being greater than the thickness of the first coating portion; an electrode terminal, passing through and confined in the pole hole, and having an end portion exposed on the second surface side of the cover plate.

[0009] In the embodiment of the present application, the first insulating coating replaces the lower plastic, thereby ensuring electrical insulation between the cover plate and the electrode assembly, as well as electrical insulation between the electrode terminal and the cover plate, while avoiding the risk of fire during thermal runaway of the energy storage device; in addition, since the second coating portion covering the weld mark is thicker, the coating effect of the second coating portion on the welding slag at the weld mark is enhanced to avoid the sharp part of the welding slag piercing the electrode lug of the electrode assembly, causing leakage, thereby improving the insulation effect between the cover plate and the electrode assembly.

[0010] According to one embodiment of the present application, the end cover assembly further includes a second insulating coating, which is located on the second surface side of the cover plate and includes a third coating portion and a fourth coating portion; the third coating portion covers at least a portion of the second surface of the cover plate and extends to the edge of the hole opening of the pole hole on the second surface, and the fourth coating portion covers the hole wall of the pole hole.

[0011] In the embodiment of the present application, by providing the second insulating coating on the second surface of the cover plate, the insulation effect between the cover plate and the electrode terminal can be effectively improved.

[0012] According to one embodiment of the present application, the electrode terminal includes an electrode column, a welding ring and a sealing ring; the side wall of the first end portion of the electrode column has a limit platform, the limit platform is limited on the first surface side of the cover plate, the sealing ring is mounted on the electrode column, and is clamped between the limit platform and the first coating portion; the welding ring is mounted on the second end portion of the electrode column, the welding ring is welded and fixed to the electrode column, and abuts against the third coating portion.

[0013] In the embodiment of the present application, the sealing ring is clamped by the limiting platform on the electrode column and the first surface of the cover plate, thereby effectively ensuring the sealing effect of the electrode column on the electrode hole while simplifying the electrode terminal structure.

[0014] According to one embodiment of the present application, the electrode terminal includes an electrode column, a welding plate and a sealing ring; the side wall of the first end portion of the electrode column has a limit platform, and the limit platform is limited to the second surface side of the cover plate; the welding plate is located on the first surface side of the cover plate, and is welded and fixed to the end face of the second end portion of the electrode column, and the sealing ring is sleeved on the electrode column and clamped between the welding plate and the first coating portion.

[0015] In the embodiment of the present application, by providing a welding plate and clamping the sealing ring between the welding plate and the first coating portion, the sealing effect of the electrode column on the pole hole is effectively guaranteed on the basis of simplifying the electrode terminal structure.

[0016] According to one embodiment of the present application, the second surface of the cover plate has an annular boss, which is arranged around the periphery of the pole hole, the third coating portion also covers the top surface of the annular boss, and the fourth coating portion also covers the inner wall of the annular boss.

[0017] In the embodiment of the present application, based on the setting of the annular boss, it is convenient to raise the height of the electrode column exposed on the second surface side of the cover plate, thereby avoiding the occurrence of an arc between the exposed end of the electrode column and the cover plate, and at the same time facilitating the connection between the exposed end of the electrode column and the external conductive component.

[0018] According to one embodiment of the present application, there are gaps between the outer edge of the first coating portion and the edge of the first surface of the cover plate, and between the outer edge of the third coating portion and the edge of the second surface of the cover plate.

[0019] In the embodiment of the present application, when the edge of the cover plate and the edge of the opening of the shell are sealed and welded, welding hot spots are avoided, thereby ensuring the sealing effect of the cover plate on the opening of the shell.

[0020] According to one embodiment of the present application, a liquid injection hole is provided on the cover plate, the first coating portion has a first avoidance area surrounding the liquid injection hole, and the third coating portion has a second avoidance area surrounding the liquid injection hole.

[0021] In the embodiment of the present application, based on the setting of the first avoidance zone and the second avoidance zone, a gap can be created between the edge of the first coating portion and the third coating portion surrounding the injection hole and the edge of the orifice of the injection hole, so as to avoid the occurrence of welding explosion points when the injection hole is sealed and welded, thereby ensuring the reliability of the sealing of the injection hole.

[0022] According to one embodiment of the present application, the electrode terminal includes an electrode column, an insulating member, a welding ring and a sealing ring; the side wall of the first end portion of the electrode column has a limit platform, and the limit platform is limited to the second surface side of the cover plate, and the insulating member is sleeved on the electrode column and clamped between the limit platform and the second surface of the cover plate; the first surface of the cover plate has a limiting groove, and the limiting groove is surrounded by the periphery of the electrode column hole, and the first coating portion covers the groove wall and groove bottom of the limiting groove; the welding ring is in the limiting groove and sleeved on the second end portion of the electrode column, and is welded and fixed to the electrode column, and the sealing ring is sleeved on the electrode column and clamped between the welding ring and the first coating portion.

[0023] In the embodiment of the present application, the setting of the upper limit groove on the cover plate facilitates the embedded setting of the welding ring, thereby realizing a thinning design of the end cover assembly, facilitating the optimization of the effective utilization of the space in the accommodating cavity of the shell, and improving the capacitance of the energy storage device.

[0024] According to one embodiment of the present application, there is a gap between the outer edge of the welding ring and the groove wall of the limiting groove, and the corners of the outer edge of the welding ring are all designed as arc chamfers.

[0025] In the embodiment of the present application, when the welding ring is limited in the limiting groove, scratches between the welding ring and the groove wall can be avoided, thereby ensuring the structural integrity of the first coating part and ensuring the insulation effect between the welding ring and the cover plate.

[0026] According to one embodiment of the present application, the end cover assembly further includes a plurality of support parts, which are fixed on the cover plate and located on the first surface side of the cover plate; the plurality of support parts are all made of metal, and the first insulating coating further includes a fifth coating part, which wraps the surfaces of the plurality of support parts.

[0027] According to one embodiment of the present application, the supporting portion includes a first connecting portion and a second connecting portion, and an arched portion connected between the first connecting portion and the second connecting portion; the first connecting portion and the second connecting portion are both fixedly connected to the cover plate, and the arched portion is used to abut the electrode assembly.

[0028] In the embodiment of the present application, by providing the structure of the support portion, not only can the contact area between the support portion and the cover plate be reduced, but also the abutment effect of the support portion on the electrode assembly can be ensured, and the material used for the support portion can be reduced.

[0029] According to an embodiment of the present application, a thickness ratio of the second coating portion to the first coating portion is greater than or equal to 1.2 and less than or equal to 3.

[0030] In the embodiment of the present application, a thickness ratio of the first coating portion and the second coating portion is set to ensure the covering effect of the first coating portion on the first surface of the cover plate and the covering effect of the second coating portion on the weld mark, while reducing the material used in the production of the first insulating coating.

[0031] According to an embodiment of the present application, a thickness ratio of the second coating portion to the first coating portion is greater than or equal to 1.5 and less than or equal to 2.

[0032] According to an embodiment of the present application, the second coating portion covers both the explosion-proof valve and the welding mark.

[0033] In the embodiment of the present application, the second coating portion covers the weld mark and the explosion-proof valve, thereby increasing the area of ​​the second coating portion to simplify the manufacturing process of the second coating portion. At the same time, it avoids electrical conduction between the explosion-proof valve and the electrode assembly, thereby improving the insulation effect between the end cover assembly and the electrode assembly.

[0034] According to one aspect of the present application, an energy storage device is provided, comprising: a shell including a housing having an opening; an electrode assembly accommodated in the housing cavity; and the end cover assembly described in the above aspect, wherein the cover plate seals the opening of the housing cavity.

[0035] According to one aspect of the present application, an electric device is provided, which includes the energy storage device described in the above aspect, and the energy storage device supplies power to the electric device.

[0036] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The above and other features and advantages of the present application will become more apparent by describing in detail example embodiments thereof with reference to the accompanying drawings.

[0038] Figure 1 is a schematic diagram showing an energy storage system according to an exemplary embodiment.

[0039] Figure 2 FIG1 is a schematic diagram of an exploded structure of an energy storage device according to an exemplary embodiment.

[0040] Figure 3 An axial top view structural schematic diagram of an end cover assembly provided by an embodiment of the present application in which the second coating portion does not cover the explosion-proof valve is illustrated.

[0041] Figure 4 The schematic diagram of the bottom-up structure of the end cover assembly provided by an embodiment of the present application is illustrated as an example, in which the second coating portion does not cover the explosion-proof valve.

[0042] Figure 5 The schematic diagram of the axial top view of the second coating portion covering the explosion-proof valve in another end cover assembly provided by an embodiment of the present application is illustrated.

[0043] Figure 6 The schematic diagram of the axial bottom view of the structure in which the second coating portion covers the explosion-proof valve in another end cover assembly provided by an embodiment of the present application is illustrated.

[0044] Figure 7 The bottom view schematic diagram of the structure of an end cover assembly provided by an embodiment of the present application is illustrated.

[0045] Figure 8 Example Figure 7 The cross-sectional structural diagram of the end cover assembly along AA' is shown.

[0046] Figure 9 A schematic top view of the structure of an end cover assembly provided in an embodiment of the present application is illustrated.

[0047] Figure 10 Example Figure 9 The cross-sectional structural diagram of the end cover assembly along AA' is shown.

[0048] Figure 11 Example Figure 10 A partially enlarged structural schematic diagram of the end cover assembly is shown.

[0049] Figure 12 Another end cap assembly provided by the embodiment of the present application is illustrated. Figure 9 The cross-sectional structural diagram of AA' is shown.

[0050] Figure 13 Another end cap assembly provided by the embodiment of the present application is illustrated. Figure 9 The cross-sectional structural diagram of AA' is shown.

[0051] Figure 14 Another end cap assembly provided by the embodiment of the present application is illustrated. Figure 9 The cross-sectional structural diagram of AA' is shown.

[0052] Figure 15 An axial bottom view schematic diagram of another end cover assembly provided in an embodiment of the present application is illustrated.

[0053] Figure 16 The bottom view schematic diagram of another end cover assembly provided in an embodiment of the present application is illustrated.

[0054] Figure 17 is a structural diagram of a power supply system according to an exemplary embodiment.

[0055] The description of the accompanying drawings is as follows:

[0056] 100. Energy storage device; 200. Electric energy conversion device; 300. High-voltage cable; 400. Power supply system; 410. Electrical equipment;

[0057] 10. Shell; 20. Electrode assembly; 30. End cap assembly;

[0058] 11. Accommodating cavity;

[0059] 31. Cover plate assembly; 32. First insulating coating; 33. Electrode terminal; 34. Second insulating coating; 35. Cover plate; 36. Explosion-proof valve; 37. Support portion;

[0060] 321, first coating portion; 322, second coating portion; 323, through hole; 324, first avoidance area;

[0061] 331. Electrode column; 332. Welding ring; 333. Sealing ring; 334. Insulator; 335. Welding plate; 336. Limiting platform;

[0062] 341, third coating portion; 342, fourth coating portion; 343, second avoidance zone;

[0063] 351, first surface; 352, second surface; 353, explosion-proof hole; 354, pole hole; 355, injection hole; 356, welding mark; 357, limiting groove; 358, annular boss;

[0064] 371. First connecting portion; 372. Second connecting portion; 373. Arched portion; 374. Ventilation hole; 375. First supporting portion; 376. Second supporting portion;

[0065] 210. First conversion device; 220. Second conversion device. DETAILED DESCRIPTION

[0066] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent like or similar structures, and thus their detailed description will be omitted.

[0067] Since the energy people need is highly temporal and spatial, in order to make rational use of energy and improve energy utilization, it is necessary to use a medium or device to store one form of energy in the same form or convert it into another form of energy, and then release it in a specific form of energy based on future application needs.

[0068] Currently, the generation of green electricity generally relies on photovoltaics, wind power, and hydropower. However, wind and solar energy are generally intermittent and highly volatile, which can cause grid instability, insufficient electricity during peak hours, and excessive electricity during off-peak hours. Unstable voltage can also damage electricity. Therefore, insufficient electricity demand or insufficient grid capacity may lead to the problem of "wind and solar power curtailment". To solve these problems, we must rely on energy storage. This means converting electrical energy into other forms of energy through physical or chemical means and storing them. When needed, this energy is converted into electrical energy and released. Simply put, energy storage is like a large "power bank", storing electricity when photovoltaic and wind energy are sufficient and releasing the stored electricity when needed.

[0069] Taking electrochemical energy storage as an example, the present application provides an energy storage device, which is equipped with a group of chemical batteries. The chemical elements in the batteries are mainly used 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 chemical batteries. When the use of external electricity reaches a peak, the stored electricity is released for use, or transferred to places where electricity is scarce for use.

[0070] Currently, energy storage (i.e., energy storage) has a wide range of application scenarios, including power generation side energy storage, grid side energy storage, and power consumption side energy storage. The corresponding types of energy storage devices include:

[0071] (1) Large-scale energy storage power stations applied to wind power and photovoltaic power stations can help renewable energy generation meet grid connection requirements and improve the utilization rate of renewable energy. As a high-quality active / reactive power supply on the power supply side, energy storage power stations can achieve load matching of electricity in time and space, enhance the ability to absorb renewable energy, reduce instantaneous power changes, reduce the impact on the power grid, improve the absorption of new energy generation, and are of great significance in grid system backup, alleviating peak load power supply pressure, and peak and frequency regulation.

[0072] (2) Energy storage containers used on the grid side are mainly used for peak load regulation, frequency regulation, and relief of grid congestion. They can realize peak load shaving and valley filling of electricity load, that is, charging the energy storage battery when the electricity load is low and releasing the stored electricity during the peak load period, thereby achieving a balance between electricity production and consumption;

[0073] (3) Small energy storage cabinets used on the power consumption side, whose main functions are self-generation and self-use of electricity, peak-valley price arbitrage, capacity cost management, and improving power supply reliability. According to different application scenarios, energy storage on the power consumption side can be divided into industrial and commercial energy storage cabinets, household energy storage devices, energy storage charging piles, etc., which are generally used in conjunction with distributed photovoltaics. Industrial and commercial users can use energy storage for peak-valley price arbitrage and capacity cost management. In the power market that implements peak-valley electricity prices, by charging the energy storage system when the electricity price is low and discharging the energy storage system when the electricity price is high, peak-valley electricity price arbitrage is achieved, reducing electricity costs. In addition, industrial enterprises that are subject to two-part electricity prices can use energy storage systems to store energy during low electricity consumption and discharge it during peak load, thereby reducing peak power and the maximum demand reported, and achieving the purpose of reducing capacity electricity charges. Household photovoltaic storage can improve the level of self-generation and self-use of electricity. Due to high electricity prices and poor power supply stability, the demand for household photovoltaic installation is driven. Considering that photovoltaic power generation occurs during the day, while user loads are generally higher at night, deploying energy storage can better utilize photovoltaic power, increasing self-generation and self-consumption while reducing electricity costs. Furthermore, energy storage is required for backup power in areas such as communication base stations and data centers.

[0074] Figure 1 This is a structural diagram of an energy storage system provided in the present application. The energy storage system is illustrated by taking the shared energy storage scenario on the generation / distribution side as an example. Of course, the energy storage device 100 of the present application is not limited to the shared energy storage scenario on the generation / distribution side.

[0075] like Figure 1 As shown, the energy storage system includes an energy storage device 100 , an electric energy conversion device 200 , and a high-voltage cable 300 .

[0076] In some embodiments of the power generation side scenario, the power conversion device 200 includes a first conversion device 210 (such as a wind power conversion device, etc.). 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. The energy storage device 100 is connected to the high-voltage cable 300 and can output smooth power for the distribution side to achieve peak and frequency regulation to ensure stable operation of the power grid; or, the wind power conversion device is directly connected to the high-voltage cable 300. Under normal power generation conditions, the high-voltage cable 300 is used to generate power for the distribution side. The high-voltage cable 300 supplies the electric energy output by the wind power conversion device to the distribution side for use, and 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 to improve the problem of new energy power generation and consumption; and when the power load is high, the power grid issues an instruction to use the power stored in the energy storage device 100 in conjunction with the high-voltage cable 300 in a grid-connected mode to transmit the electric energy to the distribution side 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.

[0077] In some embodiments on the distribution network side, the power conversion device 200 includes a second conversion device 220 (such as a photovoltaic power conversion device). The energy storage device 100 is connected to the photovoltaic power conversion device and installed downstream of the high-voltage cable 300 and between the user load. The power output by the photovoltaic power conversion device is stored in the energy storage device 100, which can respond promptly to power grid / distribution network failures and serve as a backup power source; alternatively, it can alleviate line congestion in the high-voltage cable 300 transmission line, and provide power supply support when the power grid is planned to expand, thereby delaying the economic pressure caused by grid / distribution capacity expansion.

[0078] Optionally, the power conversion device 200 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy, and mechanical energy into electrical energy. For example, the power conversion device 200 may include, but is not limited to, a photovoltaic power conversion device, a wind power conversion device, etc.

[0079] Optionally, the energy storage device 100 can be used for, 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 can also be used in data centers, military equipment, aerospace, charging piles, electric vehicles, and other fields.

[0080] Optionally, the energy storage device 100 may include, but is not limited to, single cells, as well as integrated battery systems such as battery modules, battery packs, battery clusters, mobile power supplies, and energy storage cabinets / containers. 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, or in other application forms. The embodiments of this application do not impose strict limitations on the application form of the energy storage device 100.

[0081] Optionally, the battery cells included in the energy storage device 100 may be, but are not limited to, at least one of cylindrical batteries, square batteries, prismatic batteries, or batteries of other shapes. The battery cells may be secondary batteries, which are batteries that can be recharged to activate the active materials after discharge and continue to be used. The battery cells may be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-metal hydride batteries, nickel-cadmium batteries, lead-acid batteries, etc., and this application does not specifically limit these types of batteries.

[0082] In some embodiments, as Figure 2 As shown, the energy storage device 100 includes: a shell 10, an electrode assembly 20 and an end cover assembly 30. The shell 10 includes a receiving cavity 11 with an opening. The electrode assembly 20 is accommodated in the receiving cavity 11. The end cover assembly 30 seals the opening of the receiving cavity 11.

[0083] The shell 10 may be a cylindrical structure with one end open, in which case the energy storage device 100 includes an end cap assembly 30 to seal one opening of the shell 10 . Of course, the shell 10 may also be a cylindrical structure with both ends open, in which case the energy storage device 100 includes an end cap assembly 30 and a cover plate 35 , or includes two end cap assemblies 30 , in which case the two openings of the shell 10 are sealed respectively by one end cap assembly 30 and a cover plate 35 , or two end cap assemblies 30 .

[0084] Among them, such as Figure 2 As shown, the end cap assembly 30 includes a cover plate 35 and an electrode terminal 33. The electrode terminal 33 is provided on the cover plate 35, and one end of the electrode terminal 33 is connected to the electrode assembly 20, and the other end is exposed to the outside to serve as an output end of the energy storage device 100. Figure 2 As shown, an explosion-proof hole 353 can be provided on the cover plate 35, and the end cover assembly 30 further includes an explosion-proof valve 36 installed in the explosion-proof hole 353, so that the explosion-proof valve 36 can be opened when the pressure in the accommodating chamber 11 is high, thereby achieving the discharge of gas in the accommodating chamber and improving the safety of the energy storage device 100. Figure 2 As shown, a liquid injection hole 355 may be provided on the cover plate 35 , so that after the energy storage device 100 is assembled, electrolyte can be injected into the accommodating cavity 11 along the liquid injection hole 355 to achieve infiltration of the electrode assembly 20 .

[0085] The electrode assembly 20 includes a stacked first electrode sheet, a second electrode sheet, and a diaphragm. The first electrode sheet and the second electrode sheet have opposite polarities, and the diaphragm is located between the first and second electrode sheets. The end of the electrode assembly 20 has a first electrode tab formed by a partial area of ​​the first electrode sheet and a second electrode tab formed by a partial area of ​​the second electrode sheet. The first electrode tab and the second electrode tab can be located at the same end of the electrode assembly 20 or at different ends of the electrode assembly 20. Taking the example of the first electrode tab and the second electrode tab being located at the same end of the electrode assembly 20, the end cap assembly 30 includes two electrode terminals 33, and the first electrode tab and the second electrode tab are respectively connected to the two electrode terminals 33, so that the output of electrical energy from the electrode assembly 20 is achieved through the exposed portions of the two electrode terminals 33.

[0086] It should be noted that the energy storage device 100 also includes an adapter to connect the tab of the electrode assembly 20 with the electrode terminal 33 on the end cap assembly 30 through the adapter, thereby ensuring the flow capacity between the electrode terminal 33 and the electrode assembly 20.

[0087] In the related art, the end cap assembly 30 also includes a lower plastic member, which is located on the side of the cover plate 35 facing the electrode assembly 20. The electrode terminal 33 is provided through the lower plastic member and the cover plate 35 to secure the lower plastic member and provide electrical insulation between the electrode assembly 20 and the cover plate 35. However, because the orthographic projection of the lower plastic member on the cover plate 35 obscures at least a portion of the explosion-proof hole 353, if thermal runaway of the energy storage device 100 occurs, the area of ​​the lower plastic member that obscures the explosion-proof hole 353 is easily deposited on the explosion-proof hole 353 after melting. The high-temperature aluminum beads can easily ignite the molten lower plastic member, thereby posing a fire risk.

[0088] Figure 3 The following is a schematic diagram of an axial top view of an end cap assembly 30 provided in an embodiment of the present application. Figure 4 The following is a schematic diagram of the axial bottom view of an end cap assembly 30 provided in an embodiment of the present application. Figure 3 and Figure 4 As shown, the end cap assembly 30 includes: a cover plate assembly 31, a first insulating coating 32 and an electrode terminal 33. The cover plate assembly 31 includes a cover plate 35 and an explosion-proof valve 36. The cover plate 35 has a first surface 351 and a second surface 352 opposite to each other in the thickness direction, and an explosion-proof hole 353 and a pole hole 354 extending from the first surface 351 to the second surface 352. The explosion-proof valve 36 is welded in the explosion-proof hole 353, and an annular weld mark 356 is formed on the edge of the hole of the explosion-proof hole 353 located on the first surface 351. The first insulating coating 32 is located at The cover plate 35 is on the first surface 351 side and includes a first coating portion 321 and a second coating portion 322. The first coating portion 321 covers the first surface 351 of the cover plate 35 and extends to the outer edge of the weld mark 356 and the opening edge of the pole hole 354 on the first surface 351. The second coating portion 322 covers the weld mark 356, and the thickness of the second coating portion 322 is greater than the thickness of the first coating portion 321. The electrode terminal 33 is passed through and confined in the pole hole 354, and has an end portion exposed on the second surface 352 side of the cover plate 35.

[0089] In the embodiment of the present application, the first insulating coating 32 replaces the lower plastic, thereby ensuring electrical insulation between the cover plate 35 and the electrode assembly 20, as well as electrical insulation between the electrode terminal 33 and the cover plate 35, and avoiding the risk of fire during thermal runaway of the energy storage device 100; in addition, since the second coating portion 322 covering the weld mark 356 is thicker, the coating effect of the second coating portion 322 on the welding slag at the weld mark 356 is enhanced, so as to avoid the sharp part of the welding slag piercing the electrode lug of the electrode assembly 20, causing leakage, thereby improving the insulation effect between the cover plate 35 and the electrode assembly 20.

[0090] The first insulating coating 32 may be an aluminum oxide insulating film layer formed by anodization, a PI coating formed by electrophoresis, or an insulating film layer formed by inkjet printing. Furthermore, the first coating portion 321 and the second coating portion 322 comprised by the first insulating coating 32 may be formed continuously in a single process after the explosion-proof valve 36 is welded within the explosion-proof hole 353. Alternatively, the first coating portion 321 may be formed on the first surface 351 of the cover plate 35, and then the second coating portion 322 may be formed at the annular weld mark 356 formed after the explosion-proof valve 36 is welded within the explosion-proof hole 353, thereby facilitating the provision of a thicker second coating portion 322.

[0091] Among them, when the first coating portion 321 is formed before welding the explosion-proof valve 36, the first coating portion 321 is designed to be retracted relative to the edge of the hole 353, that is, the hole edge of the explosion-proof hole 353 on the first surface 351 has an avoidance area that is not covered by the first coating portion 321, so as to avoid the occurrence of welding explosion points when the explosion-proof valve 36 is welded along the edge of the hole 353; and when the second coating portion 322 is set at the weld mark 356 formed by welding, the edge of the second coating portion 322 at least overlaps with the edge of the first coating portion 321, so as to ensure full coverage of the first surface 351 on the cover plate 35 and ensure the insulation effect between the cover plate 35 and the electrode assembly 20.

[0092] In addition, the explosion-proof valve 36 included in the end cover assembly 30 can be made of metal or non-metal. When the explosion-proof valve 36 is made of non-metal, such as Figure 3 and Figure 4 As shown, the second coating portion 322 is annular and surrounded by a through hole 323; and when the explosion-proof valve 36 is made of metal, as shown Figure 5 and Figure 6 As shown, the second coating portion 322 also covers the explosion-proof valve 36. Thus, by covering the weld mark 356 and the explosion-proof valve 36 with the second coating portion 322, the area of ​​the second coating portion 322 is increased, thereby simplifying the manufacturing process of the second coating portion 322. At the same time, electrical conduction between the explosion-proof valve 36 and the electrode assembly 20 is avoided, thereby improving the insulation effect between the end cap assembly 30 and the electrode assembly 20.

[0093] In some embodiments, the thickness ratio of the second coating portion 322 to the first coating portion 321 is greater than or equal to 1.2 and less than or equal to 3. This ensures that the first coating portion 321 covers the first surface 351 of the cover plate 35 and that the second coating portion 322 covers the welding mark 356, while reducing the material used in manufacturing the first insulating coating 32.

[0094] For example, the thickness ratio of the second coating portion 322 to the first coating portion 321 is 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, etc.

[0095] Furthermore, the thickness ratio of the second coating portion 322 to the first coating portion 321 may be set to be greater than or equal to 1.5 and less than or equal to 2. For example, the thickness ratio of the second coating portion 322 to the first coating portion 321 is 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, etc.

[0096] The thickness of the first coating portion 321 can be greater than or equal to 10 microns and preferably equal to or greater than 30 microns to ensure that the first coating portion 321 effectively covers the first surface 351 of the cover plate 35 while reducing the material used in manufacturing the first coating portion 321. For example, the thickness of the first coating portion 321 is 10 microns, 12 microns, 14 microns, 18 microns, 22 microns, 24 microns, 26 microns, 30 microns, etc.

[0097] In some embodiments, as Figure 7 and Figure 8 As shown, the electrode terminal 33 includes an electrode column 331, an insulating member 334 (such as plastic), a welding ring 332 and a sealing ring 333. The side wall of the first end of the electrode column 331 has a limit platform 336, and the limit platform 336 is limited to the second surface 352 side of the cover plate 35. The insulating member 334 is sleeved on the electrode column 331 and clamped between the limit platform 336 and the second surface 352 of the cover plate 35; the welding ring 332 is located on the first surface 351 side of the cover plate 35, the welding ring 332 is sleeved on the second end of the electrode column 331, and is welded and fixed to the electrode column 331. The sealing ring 333 is sleeved on the electrode column 331 and clamped between the welding ring 332 and the first coating portion 321.

[0098] In this way, combined with the first coating portion 321 described above, electrical insulation between the welding ring 332 and the cover plate 35 can be achieved, and at the same time, electrical insulation between the limiting platform 336 and the cover plate 35 can be achieved based on the insulating member 334, thereby ensuring electrical insulation between the electrode column 331 and the cover plate 35.

[0099] Among them, the insulating part 334 includes a radial insulating part and an axial insulating part. The radial insulating part is located in the pole hole 354 and is clamped between the side wall of the electrode column 331 and the hole wall of the pole hole 354. The axial insulating part is clamped between the limit platform 336 and the second surface 352 of the cover plate 35, thereby effectively ensuring the insulation effect between the electrode column 331 and the cover plate 35.

[0100] In some embodiments, the edge of the second end face of the electrode column 331 has a notch, and a portion of the welding ring 332 overlaps within the notch, so that a weld with a bending effect is formed based on the inner wall of the notch and the surface of the welding ring 332, thereby ensuring the sealing of the welding.

[0101] In some embodiments, as Figure 7 or Figure 8 As shown, the first surface 351 of the cover plate 35 has a limiting groove 357 . The limiting groove 357 is arranged around the periphery of the pole hole 354 , and the welding ring 332 is limited in the limiting groove 357 .

[0102] In this way, by setting the upper limit groove 357 on the cover plate 35, it is convenient to realize the embedded setting of the welding ring 332, thereby realizing the thinning design of the end cover assembly 30, facilitating the optimization of the effective utilization of the space in the accommodating cavity 11 of the shell 10, and improving the capacitance of the energy storage device 100.

[0103] The first coating portion 321 covers the groove wall and the groove bottom of the limiting groove 357 to ensure the insulation effect between the welding ring 332 and the cover plate 35 .

[0104] In some embodiments, as Figure 7 or Figure 8 As shown, there is a gap between the outer edge of the welding ring 332 and the groove wall of the retaining groove 357, and the corners of the outer edge of the welding ring 332 are all rounded and chamfered. This prevents the welding ring 332 from scratching the groove wall when the welding ring 332 is retained in the retaining groove 357, thereby maintaining the structural integrity of the first coating portion 321 and ensuring the insulation between the welding ring 332 and the cover plate 35.

[0105] The rounded corners of the outer edge of the welding ring 332 have an R angle greater than or equal to 0.1 mm and less than or equal to 0.6 mm, preferably greater than or equal to 0.15 mm and less than or equal to 0.3 mm.

[0106] In some embodiments, as Figure 9 、 Figure 10 and Figure 11 As shown, the end cap assembly 30 also includes a second insulating coating 34. The second insulating coating 34 is located on the second surface 352 of the cap plate 35 (i.e., on the side opposite the first insulating coating 32) and includes a third coating portion 341 and a fourth coating portion 342. The third coating portion 341 covers at least a portion of the second surface 352 of the cap plate 35 and extends to the edge of the terminal hole 354 on the second surface 352. The fourth coating portion 342 covers the wall of the terminal hole 354. Thus, the provision of the second insulating coating 34 on the second surface 352 of the cap plate 35 effectively improves the insulation between the cap plate 35 and the electrode terminal 33.

[0107] In combination with the electrode terminal 33 described in the above embodiment, after the second surface 352 of the cover plate 35 is covered with the second insulating layer, the insulating member 334 can be replaced based on the second insulating layer to replace the insulating member 334 included in the electrode terminal 33, that is, Figure 12 As shown, the electrode terminal 33 only includes an electrode column 331, a welding ring 332, and a sealing ring 333. The assembly method of the electrode column 331, welding ring 332, and sealing ring 333 is similar to that described in the above embodiment, with the difference that the stopper 336 on the electrode column 331 abuts the third coating portion 341. This simplifies the structure of the electrode terminal 33 while ensuring insulation, thereby improving the assembly efficiency of the electrode terminal 33 on the cover plate 35.

[0108] In other embodiments, Figure 13 As shown, the electrode terminal 33 includes an electrode column 331, a welding ring 332 and a sealing ring 333; the side wall of the first end of the electrode column 331 has a limit platform 336, the limit platform 336 is limited to the first surface 351 side of the cover plate 35, and the sealing ring 333 is sleeved on the electrode column 331 and clamped between the limit platform 336 and the first coating portion 321; the welding ring 332 is sleeved on the second end of the electrode column 331, the welding ring 332 is welded and fixed to the electrode column 331, and abuts against the third coating portion 341.

[0109] In this way, the sealing ring 333 is clamped by the limiting platform 336 on the electrode column 331 and the first surface 351 of the cover plate 35 , thereby effectively ensuring the sealing effect of the electrode column 331 on the electrode hole 354 while simplifying the structure of the electrode terminal 33 .

[0110] In some other embodiments, Figure 14 As shown, the electrode terminal 33 includes an electrode column 331, a welding plate 335 and a sealing ring 333; the side wall of the first end of the electrode column 331 has a limit platform 336, and the limit platform 336 is limited to the second surface 352 side of the cover plate 35; the welding plate 335 is located on the first surface 351 side of the cover plate 35, and is welded and fixed to the end face of the second end of the electrode column 331, and the sealing ring 333 is sleeved on the electrode column 331 and clamped between the welding plate 335 and the first coating portion 321.

[0111] In this way, by providing the welding plate 335 and clamping the sealing ring 333 between the welding plate 335 and the first coating portion 321 , the sealing effect of the electrode column 331 on the pole hole 354 is effectively guaranteed on the basis of simplifying the structure of the electrode terminal 33 .

[0112] In some embodiments, as Figure 13 or Figure 14As shown, the second surface 352 of the cover plate 35 has an annular boss 358 , which is arranged around the periphery of the pole hole 354 . The third coating portion 341 also covers the top surface of the annular boss 358 , and the fourth coating portion 342 also covers the inner wall of the annular boss 358 .

[0113] In this way, based on the setting of the annular boss 358, it is convenient to raise the height of the electrode column 331 exposed on the second surface 352 side of the cover plate 35, thereby avoiding the occurrence of an arc between the exposed end of the electrode column 331 and the cover plate 35, and at the same time facilitating the connection between the exposed end of the electrode column 331 and the external conductive component.

[0114] In combination with the above, when the electrode terminal 33 includes a welding ring 332, and the welding ring 332 abuts against the third coating portion 341, as shown in FIG. Figure 13 As shown, the welding ring 332 is supported on the annular boss 358 and abuts against the third coating portion 341 on the top surface of the annular boss 358 to ensure the support height of the welding ring 332 and at the same time ensure the insulation effect; when the limiting platform 336 on the electrode column 331 is limited to the second surface 352 side of the cover plate 35, as shown in FIG. Figure 14 As shown, the limiting platform 336 is supported on the annular boss 358 and abuts against the third coating portion 341 on the top surface of the annular boss 358 to ensure the support height of the limiting platform 336 and the insulation effect.

[0115] In some embodiments, as Figure 7 and Figure 9 As shown, there are gaps between the outer edge of the first coating portion 321 and the edge of the first surface 351 on the cover plate 35 , and between the outer edge of the third coating portion 341 and the edge of the second surface 352 on the cover plate 35 .

[0116] In this way, the first coating portion 321 can be designed to be retracted on the first surface 351 of the cover plate 35, and the third coating portion 341 can be designed to be retracted on the second surface 352 of the cover plate 35, thereby avoiding the occurrence of welding explosion points when the edge of the cover plate 35 and the opening edge of the shell 10 are sealed and welded, thereby ensuring the sealing effect of the cover plate 35 on the opening on the shell 10.

[0117] In some embodiments, as Figure 7 and Figure 9 As shown, when a liquid injection hole 355 is provided on the cover plate 35 , the first coating portion 321 has a first avoidance area 324 surrounding the liquid injection hole 355 , and the third coating portion 341 has a second avoidance area 343 surrounding the liquid injection hole 355 .

[0118] In this way, based on the setting of the first avoidance area 324 and the second avoidance area 343, a gap can be created between the edge of the first coating portion 321 and the third coating portion 341 surrounding the injection hole 355 and the edge of the opening of the injection hole 355, so as to avoid welding explosion points when welding and sealing the injection hole 355, thereby ensuring the sealing effect of the sealing nail on the injection hole 355.

[0119] Among them, there is a gap between the edges of the first coating portion 321 and the third coating portion 341 surrounding the injection hole 355 and the edge of the opening of the injection hole 355, that is, the orthographic projection of the first avoidance area 324 on the first coating portion 321 on the first surface 351 of the cover plate 35 covers the edge of the opening of the injection hole 355 on the first surface 351, and the orthographic projection of the second avoidance area 343 on the third coating portion 341 on the second surface 352 of the cover plate 35 covers the edge of the opening of the injection hole 355 on the second surface 352.

[0120] In some embodiments, as Figure 15 or Figure 16 As shown, the end cover assembly 30 further includes a plurality of support portions 37 , which are fixed on the cover plate 35 and located on the first surface 351 side of the cover plate 35 .

[0121] The plurality of support portions 37 are used to abut against the electrode assembly 20 to achieve spatial isolation between the cover plate 35 and the electrode assembly 20 , thereby ensuring the insulation effect between the cover plate 35 and the electrode assembly 20 .

[0122] Among them, the support part 37 can be made of metal or insulating material. When the support part 37 is made of metal, the support part 37 can be welded to the cover plate 35, or it can be an integrated structure with the cover plate 35; when the support part 37 is made of insulating material, the support part 37 has a fixing column, and the cover plate 35 has a fixing hole corresponding to the fixing column, and the fixing column on the support part 37 is fixed in the corresponding fixing hole by hot melting. In addition, when the support part 37 is made of metal, the first insulating coating 32 also includes a fifth coating part, and the fifth coating part wraps the surface of the multiple support parts 37. In this way, by covering the multiple support parts 37 with the fifth coating part, it is convenient to ensure the electrical insulation between the support part 37 and the electrode assembly 20 when the multiple support parts 37 abut against the electrode assembly 20.

[0123] In some embodiments, the support portion 37 is a hollow structure with one side open, and the open side of the support portion 37 faces the cover plate 35. In this way, the hollow design of the support portion 37 can reduce the material used for the support portion 37 while ensuring effective support for the electrode assembly 20.

[0124] In some embodiments, the bottom of the support portion 37 opposite the open side has one or more oblong holes. Thus, by providing a pair or more oblong holes, the material used in the support portion 37 can be further reduced while ensuring effective support for the electrode assembly 20.

[0125] In some embodiments, as Figure 15 As shown, the support portion 37 includes a first connecting portion 371 and a second connecting portion 372, and an arched portion 373 connected between the first connecting portion 371 and the second connecting portion 372; the first connecting portion 371 and the second connecting portion 372 are both fixedly connected to the cover plate 35, and the arched portion 373 is used to abut the electrode assembly 20.

[0126] In this way, by providing the structure of the support portion 37 , not only can the contact area between the support portion 37 and the cover plate 35 be reduced, but also the abutting effect of the support portion 37 on the electrode assembly 20 can be ensured, and the material used for the support portion 37 can be reduced.

[0127] In some embodiments, as Figure 15 or Figure 16 As shown, the multiple support portions 37 include at least one pair of first support portions 375 distributed along the length of the cover plate 35, and at least one second support portion 376 located between the pair of first support portions 375. In this way, through the cooperation of at least one pair of first support portions 375 and at least one second support portion 376, the stability of the support for the electrode assembly 20 is ensured, and the cover plate 35 and the electrode assembly 20 are prevented from being tilted relative to each other.

[0128] Among them, the multiple support parts 37 include one or more pairs of first support parts 375, and each pair of first support parts 375 is located on both sides of the cover plate 35 along the length direction; and when the multiple support parts 37 include multiple pairs of first support parts 375, the multiple first support parts 375 located on the same side of the cover plate 35 in the length direction can be distributed along the width direction of the cover plate 35, and the connection parts of adjacent first support parts 375 in the multiple first support parts 375 on the same side can be an integrated structure to realize the integrated design of the multiple first support parts 375 on the same side, thereby simplifying the structural design of the multiple first support parts 375.

[0129] The cover plate 35 is a long rectangular structure with a length direction parallel to the long side. Figure 15 or Figure 16 As shown, the end cap assembly 30 includes two electrode terminals 33 distributed along the length direction of the cap plate 35 , and the explosion-proof hole 353 is located between the two electrode terminals 33 .

[0130] In combination with the case of two electrode terminals 33, the two first support portions 375 of each pair are respectively arranged on the outside of the two electrode terminals 33 (i.e., the side away from the explosion-proof hole 353); or, the two first support portions 375 of each pair are respectively arranged on the inside of the two electrode terminals 33 (i.e., the side close to the explosion-proof hole 353); of course, it is also possible that one first support portion 375 of each pair is arranged on the outside of a corresponding electrode terminal 33, and the other first support portion 375 is arranged on the inside of the corresponding other electrode terminal 33.

[0131] For example, Figure 16 As shown, the plurality of support portions 37 include a pair of first support portions 375, and the pair of first support portions 375 are respectively arranged on the outside of the two electrode terminals 33; or, as shown Figure 15 As shown, the multiple support parts 37 include two pairs of first support parts 375, and each pair of first support parts 375 is respectively arranged on the outside of the two electrode terminals 33; in addition, the two first support parts 375 located on the same side of the cover plate 35 in the length direction are distributed along the width direction of the cover plate 35 and are an M-shaped integrated structure.

[0132] In addition, in combination with the above, when the support portion 37 is made of metal, the plurality of support portions 37 include a second support portion 376, and as shown in FIG. Figure 15 As shown, the first connecting portion 371 and the second connecting portion 372 included in the second supporting portion 376 can be fixed on both sides of the explosion-proof hole 353 along the width direction of the cover plate 35, and the arched portion 373 included in the second supporting portion 376 has a through-hole 374 to ensure the circulation of air when the explosion-proof valve 36 is exhausted; when the supporting portion 37 is made of insulating material, such as Figure 16 As shown, the multiple support parts 37 include two second support parts 376, and the two second support parts 376 are respectively fixed on both sides of the explosion-proof hole 353 along the width direction of the cover plate 35, so as to avoid the overlap between the positive projection of the second support part 376 on the cover plate 35 and the area enclosed by the explosion-proof hole 353, thereby reducing the accumulation of the second support part 376 in the explosion-proof hole 353 after hot melting.

[0133] In some embodiments, the end cover assembly 30 further includes connecting ribs that connect the multiple support portions 37 to achieve an integrated design of the multiple support portions 37 while ensuring the stability of the multiple support portions 37 fixed to the cover plate 35.

[0134] The material of the connecting rib is the same as that of the supporting portion 37 , and when the connecting rib is made of metal, the fifth coating portion mentioned above also covers the connecting rib to ensure the insulation effect.

[0135] The present application also provides a power supply system 400, such as Figure 17As shown, the power supply system 400 includes: an electric device 410 and the energy storage device 100 described in the above embodiment, and the energy storage device 100 is used to supply power to the electric device 410.

[0136] The electrical equipment 410 is electrically connected to the energy storage device 100. Thus, in combination with the above, the power supply system 400 of the present application can improve the safety of use during use.

[0137] In the embodiments of the present application, the terms "first", "second", and "third" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise expressly defined. Terms such as "installed", "connected", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0138] In the description of the embodiments of the present application, it should be understood that the directions or positional relationships indicated by terms such as "up", "down", "left", "right", "front", and "back" are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting the embodiments of the present application.

[0139] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the implementation methods of this application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0140] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be modified and varied in various ways. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. An end cap assembly (30), characterized in that: include: A cover plate assembly (31) comprises a cover plate (35) and an explosion-proof valve (36); the cover plate (35) has a first surface (351) and a second surface (352) opposite to each other in a thickness direction, and an explosion-proof hole (353) and a pole hole (354) extending from the first surface (351) to the second surface (352); the explosion-proof valve (36) is welded in the explosion-proof hole (353), and an annular weld mark (356) is formed on the edge of the hole of the explosion-proof hole (353) located on the first surface (351); a first insulating coating (32) located on the first surface (351) side of the cover plate (35) and comprising a first coating portion (321) and a second coating portion (322); the first coating portion (321) covers the first surface (351) of the cover plate (35) and extends to the outer edge of the welding mark (356) and the opening edge of the pole hole (354) on the first surface (351); the second coating portion (322) covers the welding mark (356), and the thickness of the second coating portion (322) is greater than the thickness of the first coating portion (321); The electrode terminal (33) is passed through and positioned in the pole hole (354), and has an end portion exposed on the second surface (352) side of the cover plate (35).

2. The end cap assembly (30) according to claim 1, characterized in that The end cap assembly (30) further includes a second insulating coating (34), the second insulating coating (34) being located on the second surface (352) side of the cover plate (35) and including a third coating portion (341) and a fourth coating portion (342); The third coating portion (341) covers at least a portion of the second surface (352) of the cover plate (35) and extends to the edge of the opening of the pole hole (354) on the second surface (352); the fourth coating portion (342) covers the hole wall of the pole hole (354).

3. The end cap assembly (30) according to claim 2, characterized in that The electrode terminal (33) includes an electrode column (331), a welding ring (332) and a sealing ring (333); The side wall of the first end portion of the electrode column (331) has a limiting platform (336), the limiting platform (336) is limited on the first surface (351) side of the cover plate (35), and the sealing ring (333) is sleeved on the electrode column (331) and clamped between the limiting platform (336) and the first coating portion (321); The welding ring (332) is sleeved on the second end of the electrode column (331), the welding ring (332) is fixed to the electrode column (331) by welding, and abuts against the third coating portion (341).

4. The end cap assembly according to claim 2, wherein: The electrode terminal (33) includes an electrode column (331), a welding plate (335) and a sealing ring (333); The side wall of the first end portion of the electrode column (331) has a limiting platform (336), and the limiting platform (336) is limited on the second surface (352) side of the cover plate (35); The welding plate (335) is located on the first surface (351) side of the cover plate (35) and is welded and fixed to the end face of the second end portion of the electrode column (331). The sealing ring (333) is sleeved on the electrode column (331) and clamped between the welding plate (335) and the first coating portion (321).

5. The end cap assembly (30) according to claim 3 or 4, characterized in that: The second surface (352) of the cover plate (35) has an annular boss (358), and the annular boss (358) is arranged around the periphery of the pole hole (354). The third coating portion (341) also covers the top surface of the annular boss (358), and the fourth coating portion (342) also covers the inner wall of the annular boss (358).

6. The end cap assembly according to claim 2, wherein: There are gaps between the outer edge of the first coating portion (321) and the edge of the first surface (351) on the cover plate (35), and between the outer edge of the third coating portion (341) and the edge of the second surface (352) on the cover plate (35).

7. The end cap assembly according to claim 2, wherein: The cover plate (35) is provided with a liquid injection hole (355), the first coating portion (321) has a first avoidance area (324) arranged around the periphery of the liquid injection hole (355), and the third coating portion (341) has a second avoidance area (343) arranged around the periphery of the liquid injection hole (355).

8. The end cap assembly (30) according to claim 1, characterized in that The electrode terminal (33) comprises an electrode column (331), an insulating member (334), a welding ring (332) and a sealing ring (333); The side wall of the first end portion of the electrode column (331) has a limiting platform (336), the limiting platform (336) is limited on the second surface (352) side of the cover plate (35), and the insulating member (334) is sleeved on the electrode column (331) and clamped between the limiting platform (336) and the second surface (352) of the cover plate (35); The first surface (351) of the cover plate (35) has a limiting groove (357), the limiting groove (357) is arranged around the periphery of the pole hole (354), and the first coating portion (321) covers the groove wall and groove bottom of the limiting groove (357); The welding ring (332) is in the limiting groove (357) and is sleeved on the second end of the electrode column (331), and is welded and fixed to the electrode column (331); the sealing ring (333) is sleeved on the electrode column (331) and clamped between the welding ring (332) and the first coating portion (321).

9. The end cap assembly according to claim 8, wherein: There is a gap between the outer edge of the welding ring (332) and the groove wall of the limiting groove (357), and the corners of the outer edge of the welding ring (332) are all designed as circular arc chamfers.

10. The end cap assembly (30) according to any one of claims 1-4, 6-9, characterized in that: The end cover assembly (30) further includes a plurality of support portions (37), wherein the plurality of support portions (37) are fixed on the cover plate (35) and are located on the first surface (351) side of the cover plate (35); The plurality of support portions (37) are all made of metal, and the first insulating coating (32) further includes a fifth coating portion, which wraps the surfaces of the plurality of support portions (37).

11. The end cap assembly according to claim 10, wherein: The support portion (37) includes a first connecting portion (371), a second connecting portion (372), and an arched portion (373) connected between the first connecting portion (371) and the second connecting portion (372); The first connecting portion (371) and the second connecting portion (372) are both fixedly connected to the cover plate (35), and the arched portion (373) is used to abut against the electrode assembly (20).

12. The end cap assembly (30) according to any one of claims 1-4, 6-9, characterized in that: A thickness ratio of the second coating portion (322) to the first coating portion (321) is greater than or equal to 1.2 and less than or equal to 3.

13. The end cap assembly of claim 11, wherein: A thickness ratio of the second coating portion (322) to the first coating portion (321) is greater than or equal to 1.5 and less than or equal to 2.

14. The end cap assembly according to any one of claims 1-4, 6-9, characterized in that: The second coating portion (322) covers both the explosion-proof valve (36) and the welding mark (356).

15. An energy storage device, characterized in that: include: A housing (10) comprising a receiving cavity (11) having an opening; An electrode assembly (20) is accommodated in the accommodating cavity (11); The end cover assembly (30) according to any one of claims 1 to 14, wherein the cover plate (35) seals the opening of the accommodating cavity (11).

16. A power supply system, characterized in that: The power supply system (400) comprises an electrical device (410) and the energy storage device (100) according to claim 15, wherein the energy storage device (100) supplies power to the electrical device (410).

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