End cover assembly, energy storage device and energy storage system

Abstract

The embodiment of the invention provides an end cover assembly, an energy storage device and an energy storage system, the end cover assembly comprises an end cover, lower plastic, a spacer and a pole assembly, the pole assembly comprises a pole, the pole comprises a main body part and a connecting part, and the main body part is convexly arranged on one surface of the thickness direction of the connecting part; the lower plastic and the end cover are stacked in the thickness direction of the end cover assembly, the pole assembly is located at one end of the end cover assembly in the length direction, the main body part sequentially penetrates through the lower plastic and the end cover, and the connecting part is located on the side, opposite to the end cover, of the lower plastic; the distance piece is arranged on the surface of the side, facing the lower plastic, of the end cover and arranged around the main body part, the connecting part is opposite to the distance piece in the thickness direction of the end cover assembly, the edge of the projection of the connecting part is completely located in the projection of the distance piece, and the edge of the projection of the connecting part and the edge of the projection of the distance piece are arranged in a spaced mode. The safety of the energy storage device can be improved.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to an end cap assembly, an energy storage device, and an energy storage system. Background Technology

[0002] With the development of energy storage technology, lithium-ion hard-shell batteries have become one of the mainstream products in the current energy storage and power battery fields. Their top cover structure is a core component to ensure the battery's sealing performance, current conduction efficiency, and safety performance.

[0003] Currently, both the terminals and the battery cells are key components in lithium-ion hard-shell batteries. The terminals and the tabs of the battery cells need to be connected through welding or other methods. During the welding process, the high temperatures generated can easily cause the lower plastic to burn through, deform, or even melt, leading to insulation failure and potentially causing short circuits between the end cap and the terminals. Summary of the Invention

[0004] This application provides an end cap assembly, an energy storage device, and an energy storage system, which can avoid problems such as the high temperature generated during welding burning through the lower plastic or causing the lower plastic to deform or even melt, and prevent the lower plastic insulation from failing, resulting in the end cap and the terminal post conducting and short-circuiting, thereby improving the safety of the energy storage device.

[0005] In a first aspect, embodiments of this application provide an end cap assembly. The end cap assembly includes: End caps, lower plastic parts, spacers; and A pole assembly, the pole assembly including a pole, the pole including a main body and a connecting part, the main body protruding from a surface of the connecting part in the thickness direction; Along the thickness direction of the end cap assembly, the lower plastic and the end cap are stacked, the pole assembly is located at one end of the length direction of the end cap assembly, the main body is sequentially inserted through the lower plastic and the end cap, and the connecting part is located on the side of the lower plastic facing away from the end cap. The spacer is located between the end cap and the lower plastic, and is disposed on the side surface of the end cap facing the lower plastic, and around the main body. Along the thickness direction of the end cap assembly, the connecting portion is opposite to the spacer. Along the thickness direction of the end cap assembly, the edge of the projection of the connecting portion is completely located within the projection of the spacer, and the edge of the projection of the connecting portion is spaced apart from the edge of the projection of the spacer.

[0006] In one embodiment, the pole assembly further includes a sealing ring, which is sleeved on the outer periphery of the main body and clamps between the lower plastic and the end cap; The spacer also includes a perforation that extends through both surfaces of the spacer in the thickness direction. Along the thickness direction of the end cap assembly, the projection of the sealing ring is completely within the projection of the perforation.

[0007] In one embodiment, the end cap further includes a liquid injection hole that penetrates both surfaces of the end cap in the thickness direction, and the lower plastic also includes a liquid injection through hole that penetrates both surfaces of the lower plastic in the thickness direction. The spacer also includes a clearance portion, which is disposed on one side edge of the spacer in the length direction of the end cap assembly, and the clearance portion extends through both surfaces of the spacer in the thickness direction. Along the thickness direction of the end cap assembly, the projections of the injection hole and the injection through hole are both completely located within the projection of the clearance portion, and the injection hole and the injection through hole are coaxially arranged and connected.

[0008] In one embodiment, the end cap includes a mounting groove recessed on the surface of the end cap facing the lower plastic. The mounting groove includes a first sub-groove and a second sub-groove, the second sub-groove being connected to and communicating with the first sub-groove along the length of the end cap assembly. At least a portion of the spacer is located within the first sub-groove and the second sub-groove.

[0009] In one embodiment, the lower plastic further includes a mounting protrusion and a supporting protrusion. The mounting protrusion protrudes from the surface of the lower plastic facing the end cap, and the mounting protrusion includes a mounting surface facing the end cap. The supporting protrusion protrudes from the mounting surface of the mounting protrusion, and the supporting protrusion includes a supporting surface facing the same direction as the mounting surface. Both the mounting protrusion and the supporting protrusion are located within the first sub-groove, and the supporting surface of the supporting protrusion faces the bottom surface of the first sub-groove.

[0010] In one embodiment, the lower plastic further includes a first limiting groove and a second limiting groove. The first limiting groove is recessed on the surface of the lower plastic facing away from the end cap, and the second limiting groove is recessed on the bottom wall surface of the first limiting groove. The first limiting groove and the second limiting groove respectively protrude on the surface of the lower plastic facing the end cap to form the mounting protrusion and the support protrusion. The connecting part has a limiting protrusion on its surface facing the main body, the connecting part is located in the first limiting groove, and the limiting protrusion is located in the second limiting groove.

[0011] In one embodiment, the spacer further includes a first surface and a second surface, the first surface and the second surface being disposed opposite to each other along the thickness direction of the spacer, the second surface having a recessed portion and a protruding portion being formed on the first surface, the recessed portion having a concave surface and the protruding portion having a convex surface; The first surface faces the end cap, the second surface faces the lower plastic, the protrusion is accommodated in the first sub-groove and the second sub-groove, the protrusion is connected to a portion of the bottom surface of the first sub-groove and a portion of the bottom surface of the second sub-groove, and the supporting surface of the supporting protrusion abuts against the concave surface.

[0012] In one embodiment, there are multiple pole posts and multiple spacers, with each spacer corresponding to one pole post assembly; The multiple spacers may have the same or different structures, and at least one of the spacers is provided with the clearance portion.

[0013] Secondly, embodiments of this application provide an energy storage device. The energy storage device includes a housing, a battery cell, and an end cap assembly. The battery cell is housed within the housing, the end cap assembly is mounted on one end of the battery cell in the height direction, and the connecting portion of the electrode post is electrically connected to the electrode tab of the battery cell. The end cap assembly is sealed within the opening of the housing.

[0014] Thirdly, embodiments of this application provide an energy storage system. The energy storage system includes the energy storage device.

[0015] In related technologies, terminals and connecting tabs are key components of batteries. Current conduction between terminals and tabs is typically achieved through welding the terminals to the connecting tabs, and vice versa. Alternatively, with technological advancements, terminals and connecting tabs can be integrally formed or the separate connecting tabs can be eliminated to reduce production costs and simplify manufacturing processes. In this case, current conduction between the terminals and tabs can be achieved directly through welding. However, the high temperatures generated during these welding processes can easily cause problems such as burn-through, deformation, or even melting of the lower plastic layer, leading to insulation failure and potentially causing a short circuit within the battery.

[0016] In this embodiment, a spacer is provided between the lower plastic and the end cap. The spacer is bonded to the surface of the end cap facing the lower plastic and is disposed around the main body of the electrode post. Along the thickness direction of the end cap assembly, the edge of the projection of the electrode post's connecting portion is completely within the projection of the spacer, and the edge of the connecting portion's projection is spaced apart from the edge of the spacer's projection. When the independent connecting piece is removed, the electrode post is directly electrically connected to the battery cell's tab through the connecting portion. The high temperature generated during welding is transferred to the lower plastic through the connecting portion. If the lower plastic is affected by the high temperature of the connecting portion, and problems such as burn-through, deformation, or even melting occur around the connecting portion, the spacer can also replace the lower plastic to perform the insulation function, preventing short circuits caused by contact between the battery cell and the connecting portion and the end cap, thus ensuring the safety of the energy storage device. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments or background art of this application, the accompanying drawings used in the embodiments or background art of this application will be described below.

[0018] Figure 1 This is a schematic diagram of the structure of an energy storage system according to an embodiment of this application; Figure 2 for Figure 1 A schematic diagram of the energy storage device in the energy storage system shown. Figure 3 for Figure 2 The diagram shows the exploded structure of the energy storage device. Figure 4 for Figure 3 A schematic diagram of the end cap assembly of the energy storage device shown from another angle; Figure 5 for Figure 3 An exploded view of the end cap assembly of the energy storage device shown. Figure 6 for Figure 4 The diagram shows an exploded view of the end cap assembly from another angle. Figure 7 for Figure 5 The diagram shows the exploded structure of the pole assembly of the end cap assembly along AA. Figure 8 for Figure 5 The diagram shows a structural schematic of the end cap assembly without the spacer component assembled with the end cap. Figure 9 for Figure 6 A bottom view of the end cap assembly shown, with the end cap and two spacers assembled. Figure 10 for Figure 3 The diagram shows a cross-sectional view of the end cap assembly of the energy storage device along the structure of BB.

[0019] The terms corresponding to the reference numerals in the figures are as follows: Energy storage system 4000, high-voltage cable 4100, first power conversion device 4200, second power conversion device 4300, energy storage device 1000, housing 200, opening 201, receiving cavity 202, battery cell 300, end cap assembly 100, end cap 10, first surface 11, second surface 12, receiving groove 13, mounting groove 14, groove bottom surface 141, groove peripheral surface 142, first sub-groove a, second sub-groove b, first groove side surface a1, first groove bottom surface a2, second groove side surface b1, second groove bottom surface b2, first through hole 15, liquid injection hole 16, lower plastic 20, third surface 21, fourth surface 22, ... A limiting groove 23, a bottom wall surface 231, a mounting protrusion 24, a mounting surface 241, a second limiting groove 25, a support protrusion 26, a support surface 261, a second through hole 27, an injection through hole 28, a spacer 30, a first surface 31, a second surface 32, a perforation 33, a clearance part 34, a protrusion 35, a convex surface 351, a first side surface 352, a recess 36, a recessed surface 361, a second side surface 362, an electrode assembly 40, an electrode 50, a connecting part 51, a main body part 52, a first connecting surface 511, a second connecting surface 512, a limiting protrusion 53, a limiting surface 531, an upper plastic 60, a plastic body 61, an extension part 62, an electrode through hole 63, a sealing ring 70, and a pressure block 80. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0021] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly specified. Furthermore, the terms "same," "equal," or "parallel" used below are all allowed to have certain tolerances.

[0022] It should be noted that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include at least one of those features.

[0023] Because the energy we need is highly time- and space-dependent, in order to utilize energy rationally and improve energy efficiency, it is necessary to store one form of energy in the same way or by converting it into another, and then release it in a specific energy form for future applications. Currently, the main way to generate green electricity is to develop green energy sources such as photovoltaics and wind power to replace fossil fuels. Currently, the generation of green electricity generally relies on solar, wind, and hydropower. However, wind and solar power are characterized by strong intermittency and large fluctuations, which can cause grid instability, insufficient power during peak hours, and excessive power during off-peak hours. Unstable voltage can also damage the power grid. Therefore, due to insufficient electricity demand or insufficient grid capacity, solving these problems requires energy storage. This involves converting electrical energy into other forms of energy through physical or chemical means and storing it. When needed, this energy can be converted back into electrical energy and released. Simply put, energy storage is like a large "power bank," storing electrical energy when solar and wind power are abundant and releasing the stored electricity when needed.

[0024] Taking electrochemical energy storage as an example, this solution provides an energy storage device for use in energy storage systems. The energy storage device is equipped with a set of chemical batteries, which mainly use the chemical elements in the batteries as energy storage media. The charging and discharging process is accompanied by the chemical reaction or change of the energy storage media. Simply put, the electrical energy generated by wind and solar energy is stored in the chemical batteries. When the use of external electrical energy reaches its peak, the stored electricity is released for use, or transferred to places with a shortage of electricity for use.

[0025] Current energy storage applications are quite widespread, including generation-side energy storage, grid-side energy storage, and consumption-side energy storage. The corresponding types of energy storage devices include: (1) Large-scale energy storage power stations applied to wind power and photovoltaic power stations can help renewable energy power generation meet grid connection requirements and improve the utilization rate of renewable energy. As a high-quality active / reactive power regulation power source on the power supply side, energy storage power stations can achieve load matching of power in time and space, enhance the absorption capacity of renewable energy, reduce instantaneous power changes, reduce the impact on the power grid, improve the absorption of new energy power generation, and are of great significance in power grid system backup, alleviating peak load power supply pressure and peak regulation and frequency regulation. (2) Energy storage containers applied on the grid side mainly function as peak shaving, frequency regulation and relief of grid congestion. In terms of peak shaving, they can realize peak 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 electricity load period, thereby achieving a balance between power production and consumption. (3) Small-scale energy storage cabinets applied to the electricity consumption side mainly function as self-consumption of electricity, peak-valley price arbitrage, capacity cost management, and improving power supply reliability. Depending on the application scenario, electricity consumption-side energy storage can be divided into industrial and commercial energy storage cabinets, residential energy storage devices, energy storage charging piles, etc., which are generally used in conjunction with distributed photovoltaic power. Considering that photovoltaic power generation occurs during the day, while users generally have higher loads at night, configuring energy storage can better utilize photovoltaic power, improve the level of self-consumption, and reduce electricity costs. In addition, communication base stations, data centers, and other fields need to configure energy storage for backup power.

[0026] In some embodiments, please refer to Figure 1 , Figure 1 This is a schematic diagram of an energy storage system according to an embodiment of this application. Figure 1 The embodiments are illustrated using a shared energy storage scenario on the generation / distribution side as an example. The energy storage device 1000 of this application is not limited to its generation / distribution side energy storage scenario.

[0027] This application provides an energy storage system 4000. The energy storage system 4000 is used to supply power to electrical equipment. The energy storage system 4000 includes: a high-voltage cable 4100, a first power conversion device 4200, a second power conversion device 4300, and the energy storage device 1000 provided in this application. In some embodiments of the power generation scenario, the second power conversion device 4300 can be a wind power conversion device. Since the electricity generated by wind power conversion is volatile, random, and intermittent, the unstable electricity output by the wind power conversion device can be stored in the energy storage device 1000 through grid connection. The energy storage device 1000 is connected to the high-voltage cable 4100 and outputs smooth electricity to supply the power consumption side of the distribution network, achieving peak shaving and frequency regulation, and stable grid operation; or, the wind power conversion device initially... Finally, it connects to the high-voltage cable 4100. Under normal power generation conditions, the power output from the wind power conversion device is supplied to the power consumption side of the distribution network via the high-voltage cable. 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 1000, reducing wind and solar curtailment rates and improving the problem of new energy power generation consumption. Furthermore, when the power load is high, the grid issues an instruction to transmit the power stored in the energy storage device 1000, along with the high-voltage cable 4100, in a grid-connected mode to supply power to the power consumption side. This provides various services for grid operation, including peak shaving, frequency regulation, and backup, fully leveraging the grid's peak shaving function, promoting peak shaving and valley filling, and alleviating grid power supply pressure. It can be understood that the energy storage device 1000 in the energy storage system 4000 is used to supply power to electrical equipment.

[0028] In some embodiments on the distribution network side, the first power conversion device 4200 can be a photovoltaic power conversion device. The energy storage device 1000 is connected to the high-voltage cable 4100 and installed downstream of the high-voltage cable 4100 and between the user load. The power output of the photovoltaic power conversion device is stored in the energy storage device 1000, which can respond in a timely manner to act as a backup power source when the power grid / distribution network fails. Alternatively, it can provide power supply support to alleviate line congestion when the high-voltage cable 4100 transmission line is blocked, and to delay the economic pressure caused by the expansion of the power grid / distribution capacity when the power grid is planned to be expanded.

[0029] Optionally, the first power conversion device 4200 may include, but is not limited to, a wind power conversion device, and the second power conversion device 4300 may include, but is not limited to, a photovoltaic power conversion device. The first power conversion device 4200 and the second power conversion device 4300 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy and mechanical energy into electrical energy.

[0030] Optionally, the energy storage device 1000 may include, but is not limited to, energy storage applications 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 applied in multiple fields such as data centers, aerospace, charging piles, and electric vehicles.

[0031] Optionally, the energy storage device 1000 may include, but is not limited to, single-cell batteries, or battery modules, battery packs, battery clusters, power banks, energy storage cabinets / containers, and other battery integrated systems composed of single-cell batteries. The actual application form of the energy storage device 1000 provided in this application embodiment may be, but is not limited to, the listed products, and may also be other application forms. This application embodiment does not strictly limit the application form of the energy storage device 1000. This application embodiment only uses a multi-cell battery as an example for illustration.

[0032] Optionally, when the energy storage device 1000 is a single battery cell, the energy storage device 1000 can be, but is not limited to, at least one of cylindrical, square, prismatic, or other shaped batteries.

[0033] Optionally, the battery cell can be a rechargeable battery, which refers to a battery cell that can be recharged after discharge to activate the active materials and continue to be used. The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application does not specifically limit it.

[0034] Please see Figure 2 and Figure 3 , Figure 2 for Figure 1 The diagram shown is a structural schematic of an energy storage device in an energy storage system. Figure 3 for Figure 2 The diagram shows the exploded structure of the energy storage device.

[0035] For ease of description, the width direction of the energy storage device 1000 is defined as the X-axis, the length direction as the Y-axis, and the height direction as the Z-axis. The X-axis, Y-axis, and Z-axis are all perpendicular to each other.

[0036] The directional terms such as "upper," "lower," "bottom," "top," "right," and "left" mentioned in the embodiments of this application are based on the appendix to the specification. Figure 2 and Figure 3 The description is based on the orientation shown. It does not constitute a limitation on the actual application scenario of the energy storage device 1000. Specifically, the positive direction toward the Z-axis is defined as the top or top of the energy storage device 1000, and the negative direction toward the Z-axis is defined as the bottom or bottom of the energy storage device 1000.

[0037] like Figure 2 and Figure 3 As shown, the energy storage device 1000 includes a housing 200, an end cap assembly 100, and a battery cell 300. The housing 200 has an opening 201 and a receiving cavity 202. The opening 201 and the receiving cavity 202 are in communication. The battery cell 300 is housed within the receiving cavity 202. The end cap assembly 100 is mounted on one side of the battery cell 300 in the height direction (i.e., the Z-axis direction) and seals the opening 201 of the housing 200 to isolate the internal environment of the energy storage device 1000 from the external environment.

[0038] Please refer to the following: Figure 4 , Figure 5 and Figure 6 , Figure 4 for Figure 3 The diagram shows the structure of the end cap assembly of the energy storage device from another angle. Figure 5 for Figure 3 The diagram shows an exploded view of the end cap assembly of the energy storage device. Figure 6 for Figure 4 The diagram shows an exploded view of the end cap assembly from another angle.

[0039] The end cap assembly 100 includes an end cap 10, a lower plastic 20, a spacer 30, and a pole post assembly 40. The end cap 10 and the lower plastic 20 are stacked and connected along the thickness direction (i.e., the Z-axis direction) of the end cap assembly 100. The pole post assembly 40 is mounted at one end of the end cap assembly 100 along its length direction (i.e., the Y-axis direction). The spacer 30 is bonded to a surface of the end cap 10 facing the lower plastic 20 along its thickness direction (i.e., the Z-axis direction) and separates the end cap 10 and the lower plastic 20 around the pole post assembly 40. In this embodiment, both the end cap 10 and the lower plastic 20 are generally rectangular plates. The end cap 10 is made of plain aluminum. The lower plastic 20 is made of a plastic insulating material. The length direction of the end cap 10 is approximately the same as the length direction of the lower plastic 20, and the width direction of the end cap 10 is approximately the same as the width direction of the lower plastic 20. There are two pole post assemblies 40 and two spacers 30. Each spacer 30 is disposed corresponding to one pole assembly 40 and separates the end cap 10 and the lower plastic 20 around the pole assembly 40. In some embodiments, the number of pole assemblies 40 and spacers 30 may be two or more. This application does not limit this.

[0040] In this embodiment, two pole post assemblies 40 are respectively mounted at both ends of the end cap assembly 100 along its length, and the two pole post assemblies 40 are spaced apart from each other. Figure 5 and Figure 6 As shown, each electrode assembly 40 includes an electrode 50, a clamping block 80, an upper plastic 60, and a sealing ring 70. The upper plastic 60 and the sealing ring 70 are both fitted around the outer periphery of the electrode 50. The electrode 50 passes sequentially through the lower plastic 20 and the end cap 10, and is insulated and sealed to the end cap 10 through the cooperation of the upper plastic 60, the sealing ring 70, and the lower plastic 20. The electrode 50 is used for electrical connection with the tabs of the battery cell 300, such as through welding for electrical conduction. Along the Z-axis, the clamping block 80 is located on the side of the end cap 10 opposite to the lower plastic 20, and is fitted around the outer periphery of the portion of the electrode 50 that protrudes from the end cap 10. The clamping block 80 is separated from and insulated from the end cap 10 by the upper plastic 60.

[0041] One terminal assembly 40 is a positive terminal assembly, comprising a positive terminal 50, a positive clamping block 80, a positive upper plastic 60, and a positive sealing ring 70. The other terminal assembly 40 is a negative terminal assembly, comprising a negative terminal 50, a negative clamping block 80, a negative upper plastic 60, and a negative sealing ring 70. The positive terminal is used for electrical connection to the positive tab of the battery cell 300. The negative terminal is used for electrical connection to the negative tab of the battery cell 300.

[0042] like Figure 5 and Figure 6As shown, 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 back to back along the thickness direction of the end cap 10 (i.e., the Z-axis direction).

[0043] As Figure 5 shown, the end cap 10 further includes a receiving groove 13. The receiving groove 13 is recessed in the first surface 11 of the end cap 10 and is recessed in the direction of the second surface 12. The receiving groove 13 is used to receive at least part of the upper plastic 60 to limit and fix the upper plastic 60 on the end cap 10. In this embodiment, the number of the receiving grooves 13 is the same as the number of the pole column assemblies 40, which is two. The structures of the two receiving grooves 13 are substantially the same, and the two receiving grooves 13 are respectively arranged at opposite ends in the length direction of the end cap 10 (i.e., the Y-axis direction).

[0044] As Figure 6 shown, the end cap 10 further includes a mounting groove 14. The mounting groove 14 is recessed in the second surface 12 of the end cap 10 and is recessed in the direction of the first surface 11. The mounting groove 14 includes a first sub-groove a and a second sub-groove b. The first sub-groove a and the second sub-groove b are connected and communicate with each other along the Y-axis direction. The first sub-groove a is used to receive at least part of the lower plastic 20. Both the first sub-groove a and the second sub-groove b are used to receive at least part of the spacer 30. In this embodiment, the number of the mounting grooves 14 is the same as the number of the pole column assemblies 40, which is two. The structures of the two mounting grooves 14 are substantially the same, and both are "convex"-shaped grooves, and the two mounting grooves 14 are respectively arranged at opposite ends in the length direction of the end cap 10 (i.e., the Y-axis direction).

[0045] The first sub-groove a includes a first groove side surface a1 and a first groove bottom surface a2. The orientation of the first groove bottom surface a2 is the same as that of the second surface 12. The first groove side surface a1 is connected to the first groove bottom surface a2 and the second surface 12. In this embodiment, the first sub-groove a is substantially a rectangular groove.

[0046] The second sub-groove b includes a second groove side surface b1 and a second groove bottom surface b2. The orientation of the second groove bottom surface b2 is the same as that of the second surface 12. The second groove side surface b1 is connected to the second groove bottom surface b2 and the second surface 12. In this embodiment, the second sub-groove b is substantially an arc-shaped groove.

[0047] In this embodiment, the second groove bottom surface b2 of the second sub-groove b is connected to the first groove bottom surface a2 of the first sub-groove a and together with the first groove bottom surface a2 constitutes the groove bottom surface 141 of the mounting groove 14. The second groove side surface b1 of the second sub-groove b is connected to the first groove side surface a1 of the first sub-groove a and together with the first groove side surface a1 constitutes the groove peripheral surface 142 of the mounting groove 14. It can be understood that the second sub-groove b is arranged on one side of the first sub-groove a away from the central axis of the end cap 10 in the width direction and is recessed in the first groove side surface a1 of the first sub-groove a.

[0048] As Figure 5 and Figure 6 As shown, the end cap 10 also includes a first through hole 15. In this embodiment, the number of first through holes 15 is the same as the number of mounting slots 14 and receiving slots 13, which is two. Each first through hole 15 penetrates the bottom wall of a receiving slot 13 and the first bottom surface a2 of a first sub-slot a. The first through hole 15 is used for the pole post 50 to pass through. In this embodiment, the two first through holes 15 have the same structure and are both circular holes.

[0049] The end cap 10 also includes an injection hole 16. The injection hole 16 extends through the first surface 11 and the second surface 12 of the end cap 10. Along the Y-axis, the injection hole 16 is located between two first through holes 15 and is spaced apart from two mounting grooves 14. The distance from the injection hole 16 to one first through hole 15 is greater than the distance from the injection hole 16 to the other first through hole 15. The injection hole 16 is used to allow electrolyte to enter the interior of the energy storage device 1000.

[0050] like Figure 5 and Figure 6 As shown, the lower plastic 20 includes a third surface 21 and a fourth surface 22. The third surface 21 and the fourth surface 22 are arranged facing away from each other along the thickness direction (i.e., the Z-axis direction) of the lower plastic 20.

[0051] The lower plastic 20 also includes a first limiting groove 23. The first limiting groove 23 is recessed in the fourth surface 22 of the lower plastic 20, and a mounting protrusion 24 is correspondingly formed on the third surface 21 of the lower plastic 20. The first limiting groove 23 is used to mate with the pole post 50. The mounting protrusion 24 protrudes from the third surface 21 of the lower plastic 20. The mounting protrusion 24 is used to mate with the mounting groove 14 of the end cap 10. In this embodiment, the number of first limiting grooves 23 and mounting protrusions 24 is the same, both being two. The two first limiting grooves 23 have roughly the same structure, both being rectangular grooves. The two mounting protrusions 24 have roughly the same structure, both being rectangular protrusions. Each first limiting groove 23 and each mounting protrusion 24 are located at the same end in the length direction (i.e., the Y-axis direction) of the lower plastic 20.

[0052] Each first limiting groove 23 includes a bottom wall surface 231. The bottom wall surface 231 faces the same direction as the fourth surface 22 of the lower plastic 20. Each mounting protrusion 24 includes a mounting surface 241. The mounting surface 241 faces the same direction as the third surface 21 of the lower plastic 20.

[0053] The lower plastic 20 also includes a second limiting groove 25. In this embodiment, there are two second limiting grooves 25. Each second limiting groove 25 has a recessed bottom wall surface 231 of the first limiting groove 23, and a supporting protrusion 26 is formed on the mounting surface 241 of the mounting protrusion 24. The second limiting groove 25 is used to cooperate with the pole post 50 to limit the pole post 50 to the lower plastic 20. The supporting protrusion 26 protrudes from the mounting surface 241 of the mounting protrusion 24. The supporting protrusion 26 is used to abut against the spacer 30 bonded to the end cap 10. The supporting protrusion 26 includes a supporting surface 261. The supporting surface 261 and the mounting surface 241 of the mounting protrusion 24 have the same orientation. Along the thickness direction of the lower plastic 20, the projection of the second limiting groove 25 is completely within the projection of the first limiting groove 23, and the projection of the supporting protrusion 26 is completely within the projection of the mounting protrusion 24. In this embodiment, the two second limiting grooves 25 have approximately the same structure, both being circular grooves. The two supporting protrusions 26 have roughly the same structure, both being circular protrusions.

[0054] It is understood that the second limiting groove 25 and the first limiting groove 23 are connected, and a step is formed between the second limiting groove 25 and the first limiting groove 23. Along the Z-axis, the distance from the bottom wall of the second limiting groove 25 to the fourth surface 22 is greater than the distance from the bottom wall surface 231 of the first limiting groove 23 to the fourth surface 22. A step is formed between the mounting protrusion 24 and the supporting protrusion 26. Along the Z-axis, the distance from the supporting surface 261 of the limiting protrusion 53 to the third surface 21 is greater than the distance from the mounting surface 241 of the mounting protrusion 24 to the third surface 21.

[0055] The lower plastic 20 also includes a second through hole 27. In this embodiment, there are two second through holes 27. Each second through hole 27 passes through a second limiting groove 25 and a support surface 261 of a support protrusion 26. The second through hole 27 is used for the pole post 50 to pass through. In this embodiment, the two second through holes 27 have roughly the same structure and are both circular holes.

[0056] The lower plastic 20 also includes an injection through-hole 28. The injection through-hole 28 extends through the third surface 21 and the fourth surface 22 of the lower plastic 20. The injection through-hole 28 is located between two second through holes 27, and the injection through-hole 28 is spaced apart from the two first limiting grooves 23. The distance from the injection through-hole 28 to one second through hole 27 is greater than the distance from the injection through-hole 28 to the other second through hole 27. The injection through-hole 28 is used to mate with the injection hole 16 of the end cap 10 to allow electrolyte to enter the interior of the energy storage device 1000.

[0057] Please refer to the following: Figure 5 , Figure 6 and Figure 7 , Figure 7 for Figure 5 The diagram shows the exploded structure of the pole assembly of the end cap assembly along line AA.

[0058] In this embodiment, the two pole post assemblies 40 have roughly the same structure, that is, the two pole posts 50 have roughly the same structure, the two sealing rings 70 have roughly the same structure, the upper plastic 60 has roughly the same structure, and the pressure block 80 has roughly the same structure.

[0059] Each pole post 50 includes a connecting portion 51 and a main body portion 52. The main body portion 52 protrudes from a surface of the connecting portion 51 in the thickness direction (i.e., the Z-axis direction). In this embodiment, the connecting portion 51 is generally a rectangular plate. The main body portion 52 is generally a circular cylinder.

[0060] The connecting portion 51 includes a first connecting surface 511 and a second connecting surface 512. The first connecting surface 511 and the second connecting surface 512 are disposed facing away from each other along the thickness direction of the connecting portion 51. The connecting portion 51 is used for direct electrical connection with the tab of the battery cell 300.

[0061] The connecting portion 51 also includes a limiting protrusion 53. The limiting protrusion 53 protrudes from the first connecting surface 511 of the connecting portion 51. The limiting protrusion 53 is used to accommodate within the second limiting groove 25 of the lower plastic 20 to further limit the pole post 50 and the lower plastic 20. The limiting protrusion 53 includes a limiting surface 531. The limiting surface 531 has the same orientation as the first connecting surface 511 of the connecting portion 51. In this embodiment, the limiting protrusion 53 is approximately a circular protrusion.

[0062] The main body 52 protrudes from the limiting surface 531 of the limiting protrusion 53. The main body 52 includes a peripheral side surface. The peripheral side surface is connected to the limiting surface 531 of the limiting protrusion 53. Along the height direction of the pole post 50 (i.e., the Z-axis direction), the projection of the main body 52 is completely within the projection of the limiting protrusion 53, that is, the projection of the main body 52 is completely within the projection of the connecting part 51.

[0063] Each sealing ring 70 is fitted around the outer periphery of the main body 52 of a pole post 50. In this embodiment, both sealing rings 70 are made of plastic insulating material and are both approximately circular.

[0064] Each upper plastic insert 60 is fitted around the outer periphery of the main body 52 of an electrode post 50. Each upper plastic insert 60 includes a plastic body 61 and an extension 62. Along the Z-axis, the extension 62 protrudes from one end of the plastic body 61. The plastic body 61 and the extension 62 are coaxially arranged and together form an electrode post through hole 63 for the electrode post 50 to pass through. That is, the electrode post through hole 63 is a stepped circular hole. In this embodiment, both upper plastic inserts 60 are made of plastic insulating material.

[0065] In some embodiments, the structures of the two pole post assemblies 40 may be different; that is, the structures of the two pole posts 50 may be different, and / or the structures of the two sealing rings 70 may be different, and / or the structures of the upper plastic 60 may be different, and / or the structures of the pressure block 80 may be different. This application does not impose any limitations on this.

[0066] Please combine Figure 5 , Figure 6 and Figure 8 , Figure 8 for Figure 5 The diagram shown illustrates the structure of the end cap assembly without the spacer piece assembled with the end cap. It should be noted that... Figure 5 The spacer shown in the diagram represents the state after assembly with the end cap.

[0067] In this embodiment, the two spacers 30 have roughly the same structure as the end cap 10 before assembly, and the two spacers 30 have roughly the same structure as the end cap 10 after assembly.

[0068] like Figure 8 As shown, the two spacers 30 are in their state before assembly with the end cap 10, both being flat, U-shaped sheet structures. Each spacer 30 includes a first surface 31 and a second surface 32. The first surface 31 and the second surface 32 are arranged facing away from each other along the thickness direction (i.e., the Z-axis direction) of the spacer 30. The spacers 30 can be made of materials with heat insulation and electrical insulation properties. In this embodiment, the spacers 30 are made of high-temperature adhesive, which not only withstands high temperatures but also provides insulation.

[0069] Each spacer 30 also includes a through-hole 33. The through-hole 33 extends through the first surface 31 and the second surface 32 of the spacer 30. The through-hole 33 is for the main body portion 52 of the pole post 50 to pass through, and the diameter of the through-hole 33 is larger than the diameter of the main body portion 52 of the pole post 50. In this embodiment, the through-hole 33 is approximately a circular hole.

[0070] Each spacer 30 also includes a clearance portion 34. The clearance portion 34 is provided on one side edge of the spacer 30 along its length direction (i.e., the Y-axis direction) and extends through the first surface 31 and the second surface 32 of the spacer 30. The clearance portion 34 of one spacer 30 is used to clear the injection hole 16 of the end cap 10. In this embodiment, the clearance portion 34 is generally a rectangular notch.

[0071] In this embodiment, the two spacers 30 have the same structure, avoiding the need to manufacture two different structural forms of spacers 30, simplifying the process steps, and saving manufacturing costs. In some embodiments, the two spacers 30 may have different structures. One spacer 30 may not include the clearance portion 34, while the other spacer 30 may have the clearance portion 34 to avoid the injection hole 16. This application does not impose any limitations on this.

[0072] like Figure 5 and Figure 6 As shown in Figure 6 , the two spacers 30 are in a state assembled with the end cap 10, and both are non-planar sheet structures in the shape of "concave". Each spacer 30 forms a recess 36 on the second surface 32. The recess 36 is recessed in the second surface 32, and a convex portion 35 is correspondingly formed on the first surface 31. The convex portion 35 protrudes from the first surface 31 of the spacer 30. The recess 36 and the convex portion 35 are both provided on one side edge of the spacer 30 in the length direction away from the avoidance portion 34. Among them, the convex portion 35 includes a convex surface 351 and a first side surface 352. The convex surface 351 has the same orientation as the first surface 31 of the spacer 30, and the first side surface 352 is connected to the convex surface 351 and the first surface 31. The recess 36 includes a concave surface 361 and a second side surface 362. The concave surface 361 has the same orientation as the second surface 32 of the spacer 30, and the second side surface 362 is connected to the concave surface 361 and the second surface 32. The through hole 33 penetrates through the concave surface 361 of the recess 36 and the convex surface 351 of the convex portion 35. In this embodiment, the shapes of the recess 36 and the convex portion 35 are both adapted to the shape of the mounting groove 14 of the end cap 10. The recess 36 is generally a groove in the shape of "convex", and the convex portion 3五十五 is generally a protrusion in the shape of "convex". Before the convex portion 35 and the recess 36 are formed, the convex surface 351 and the first side surface 352 of the convex portion 35 can be regarded as part of the first surface 31 of the insulating and heat-insulating pad, and the concave surface 361 and the second side surface 362 of the recess 36 can be regarded as part of the second surface 32 of the insulating and heat-insulating pad.

[0073] Please refer to Figure 6 and Figure 9 , Figure 9 which is Figure 6 the bottom view of the assembly of the end cap of the end cap assembly shown in Figure 6 and the two spacers.

[0074] In this embodiment, the two spacers 30 are both installed on the same side in the thickness direction of the end cap 10 and are adhesively fixed to the end cap 10. Specifically, the first surface 31 of each spacer 30 faces the second surface 12 of the end cap 10 and is adhesively bonded to the second surface 12 of the end cap 10 around a first sub-groove a and part of the second surface 12 of the end cap 10 around a second sub-groove b. A part of the convex portion 35 of each spacer 30 is received in the first sub-groove a, and another part is received in the second sub-groove b. The convex surface 351 of the convex portion 35 is adhesively bonded to part of the first groove bottom surface a2 of the first sub-groove a and at least part of the second groove bottom surface b2 of the second sub-groove b. The first side surface 352 of the convex portion 35 is adhesively bonded to the first groove side surface a1 of the first sub-groove a and at least part of the second groove side surface b1 of the second sub-groove b. It can be understood that when the spacer 30 is installed on the end cap 10, the spacer 30 forms a convex portion 35 adapted to the shape of the mounting groove 14 according to the shape of the end cap 10. The end cap 10 is provided with a second sub-groove b, and a part of the spacer 30 is located in the second sub-groove b, which is beneficial for subsequent rework and glue removal of the end cap assembly 100.

[0075] The perforation 33 of each spacer 30 is coaxially arranged and connected with a first through hole 15 of the end cap 10, and the diameter of the perforation 33 is larger than the diameter of the first through hole 15, so as to avoid the subsequent installation of the sealing ring 70.

[0076] The clearance portions 34 of the two spacers 30 are positioned opposite each other and spaced apart along the Y-axis. The injection hole 16 of the end cap 10 is completely located within the clearance portion 34 of one of the spacers 30, that is, along the Z-axis, the projection of the injection hole 16 is completely located within the projection of the clearance portion 34 of the spacer 30, so as to avoid affecting the subsequent energy storage device 1000 from injecting liquid into the interior through the injection hole 16.

[0077] Please refer to the following: Figure 5 , Figure 6 and Figure 10 , Figure 10 for Figure 3 The diagram shows a cross-sectional view of the end cap assembly of the energy storage device along the structure of BB.

[0078] The lower plastic 20 is assembled with the end cap 10, which is equipped with the spacer 30. Specifically, the third surface 21 of the lower plastic 20 faces the end cap 10 and the spacer 30. A portion of the third surface 21 is opposite to and spaced apart from the second surface 12 of the end cap 10 and a portion of the concave surface 361 of the recess 36 in the mounting groove 14. Another portion of the third surface 21 abuts against the second surface 32 of the spacer 30.

[0079] The mounting protrusion 24 and support protrusion 26 of the lower plastic 20 are both housed within the first sub-groove a of the mounting groove 14 of the end cap 10. Along the Z-axis, the projections of the support protrusion 26 and the mounting protrusion 24 are completely within the projection of the first sub-groove a. The support protrusion 26 abuts against the spacer 30 within the mounting groove 14, and the support surface 261 of the support protrusion 26 abuts against the concave surface 361 of the recess 36. The mounting surface 241 of the mounting protrusion 24 and the concave surface 361 of the recess 36 are opposite to and spaced apart along the Z-axis. The second through hole 27 of the lower plastic 20 is coaxially arranged and communicates with the first through hole 15 of the end cap 10, allowing the main body 52 of the pole post 50 to pass through. The liquid injection through hole 28 of the lower plastic 20 and the liquid injection hole 16 of the end cap 10 are both completely located within the clearance portion 34 of the spacer 30, and the liquid injection through hole 28 and the liquid injection hole 16 are coaxially arranged and communicate with each other. That is, along the thickness direction of the end cap assembly 100, the projections of the liquid injection through hole 28 and the liquid injection hole 16 are completely located within the projection of the avoidance part 34, so that the spacer 30 will not block the electrolyte from flowing from the liquid injection hole 16 to the liquid injection through hole 28, thus ensuring the efficiency of the subsequent energy storage device 1000 injecting liquid into the interior.

[0080] The upper plastic 60 is mounted on the side of the end cap 10 facing away from the lower plastic 20. Specifically, the plastic body 61 of the upper plastic 60 is inserted into the receiving groove 13 of the end cap 10, and the extension 62 passes through the first through hole 15 of the end cap 10 to limit and fix the upper plastic 60 to the end cap 10. The pole through hole 63 of the upper plastic 60 and the first through hole 15 of the end cap 10 are coaxially arranged.

[0081] A sealing ring 70 is fitted around the outer periphery of the main body 52 of the electrode post 50, and is installed together with the electrode post 50 in the lower plastic 20, upper plastic 60, and end cap 10. Specifically, the main body 52 of the electrode post 50 passes sequentially through the second through hole 27 of the lower plastic 20, the through hole 33 of the spacer 30, the first through hole 15 of the end cap 10, and the electrode post through hole 63 of the upper plastic 60. The connecting part 51 of the electrode post 50 is located in the first limiting groove 23 of the lower plastic 20, and the first connecting surface 511 of the connecting part 51 abuts against the bottom wall surface 231 of the first limiting groove 23 to limit and fix the electrode post 50 to the lower plastic 20. The limiting protrusion 53 of the electrode post 50 is located in the second limiting groove 25 of the lower plastic 20, and the limiting surface 531 of the limiting protrusion 53 abuts against the bottom wall of the second limiting groove 25 to further limit and fix the electrode post 50 and the lower plastic 20.

[0082] The sealing ring 70 is located within the second limiting groove 25 of the lower plastic 20 and is clamped between the pole post 50, the end cap 10, the lower plastic 20, and the upper plastic 60, resulting in an interference fit between the sealing ring 70 and the pole post 50, the end cap 10, the lower plastic 20, and the upper plastic 60, thereby achieving sealing and insulation of the end cap assembly 100. It can be understood that the pole post 50 can be insulated and sealed from the end cap 10 through the upper plastic 60, the sealing ring 70, and the lower plastic 20.

[0083] In this embodiment, the outer diameter of the sealing ring 70 is less than or equal to the diameter of the perforation 33 of the spacer 30. That is, along the thickness direction of the end cap assembly 100, the projection of the sealing ring 70 is completely located within the projection of the perforation 33. In other words, the edge of the projection of the sealing ring 70 can coincide with the edge of the projection of the perforation 33, or the edge of the projection of the sealing ring 70 can be spaced apart from the edge of the projection of the perforation 33, so as to avoid interference between the sealing ring 70 and the spacer 30, fully ensuring the effective sealing area of ​​the sealing ring 70 for the pole 50, the lower plastic 20, the end cap 10, and the upper plastic 60, preventing the sealing life of the sealing ring 70 from being shortened, and thus ensuring the sealing performance of the end cap assembly 100.

[0084] The pressure block 80 is mounted on the side of the upper plastic 60 facing away from the end cap 10 and is sleeved on the outer periphery of the main body 52 of the pole post 50. The pressure block 80 is inserted into the pole post through hole 63 of the upper plastic 60 and is limited and fixed by the upper plastic 60 and the main body 52.

[0085] Combination Figure 3The end cap assembly 100 is mounted on the battery cell 300 and is housed together with the battery cell 300 within the housing 200. The connecting part 51 of the terminal post 50 is directly electrically connected to the electrode tab (not shown) of the battery cell 300.

[0086] When the connecting part 51 of the electrode post 50 is welded to the electrode tab, the welding generates high temperature, which is transmitted to the lower plastic 20 through the connecting part 51. The lower plastic 20 is easily burned through, deformed, or even melted due to the high temperature. A spacer 30 is provided between the end cap 10 around the main body 52 and the lower plastic 20. Along the thickness direction of the end cap assembly 100, the edge of the projection of the connecting part 51 is completely located within the projection of the spacer 30, and the edge of the projection of the connecting part 51 is spaced apart from the edge of the projection of the spacer 30. Even if the high temperature generated by the direct welding of the electrode tab and the electrode post 50 causes the lower plastic 20 around the electrode post assembly 40 to be burned through, deformed, or even melted, the spacer 30 can replace the part of the lower plastic 20 that has lost its insulating properties, separating and insulating the connecting part 51 and the cell 300 from the end cap 10, and preventing short circuits in the energy storage device 1000.

[0087] It should be noted that the above description of the assembly sequence does not represent the assembly order of the end cap assembly 100 in actual application.

[0088] In related technologies, terminals and connecting tabs are key components of batteries. Current conduction between terminals and tabs is typically achieved through welding the terminals to the connecting tabs, and vice versa. Alternatively, with technological advancements, terminals and connecting tabs can be integrally formed or the separate connecting tabs can be eliminated to reduce production costs and simplify manufacturing processes. In this case, current conduction between the terminals and tabs can be achieved directly through welding. However, the high temperatures generated during these welding processes can easily cause problems such as burn-through, deformation, or even melting of the lower plastic layer, leading to insulation failure and potentially causing a short circuit within the battery.

[0089] In this embodiment, a spacer 30 is provided between the lower plastic 20 and the end cap 10. The spacer 30 is bonded to the surface of the end cap 10 facing the lower plastic 20 and is disposed around the main body 52 of the pole post 50. Along the thickness direction of the end cap assembly 100, the edge of the projection of the connecting portion 51 of the pole post 50 is completely located within the projection of the spacer 30, and the edge of the projection of the connecting portion 51 is spaced apart from the edge of the projection of the spacer 30. When the independent connecting piece is removed, the pole post 50 is directly electrically connected to the tab of the cell 300 through the connecting portion 51. The high temperature generated during welding is transferred to the lower plastic 20 through the connecting portion 51. If the lower plastic 20 is affected by the high temperature of the connecting portion 51, and problems such as burn-through, deformation, or even melting occur around the connecting portion 51, the spacer 30 can also replace the lower plastic 20 to perform the insulation function, preventing the cell 300 and the connecting portion 51 from contacting the end cap 10 and causing a short circuit, thus ensuring the safety of the energy storage device 1000.

[0090] The above are merely some embodiments and implementation methods of this application. The scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An end cap assembly, characterized in that, The end cap assembly includes: End caps, lower plastic parts, spacers; and A pole assembly, the pole assembly including a pole, the pole including a main body and a connecting part, the main body protruding from a surface of the connecting part in the thickness direction; Along the thickness direction of the end cap assembly, the lower plastic and the end cap are stacked, the pole assembly is located at one end of the length direction of the end cap assembly, the main body is sequentially inserted through the lower plastic and the end cap, and the connecting part is located on the side of the lower plastic facing away from the end cap. The spacer is located between the end cap and the lower plastic, and is disposed on the side surface of the end cap facing the lower plastic, and around the main body. Along the thickness direction of the end cap assembly, the connecting portion is opposite to the spacer. Along the thickness direction of the end cap assembly, the edge of the projection of the connecting portion is completely located within the projection of the spacer, and the edge of the projection of the connecting portion is spaced apart from the edge of the projection of the spacer.

2. The end cap assembly according to claim 1, characterized in that, The pole assembly also includes a sealing ring, which is sleeved on the outer periphery of the main body and clamps between the lower plastic and the end cap; The spacer also includes a perforation that extends through both surfaces of the spacer in the thickness direction. Along the thickness direction of the end cap assembly, the projection of the sealing ring is completely within the projection of the perforation.

3. The end cap assembly according to claim 1, characterized in that, The end cap also includes an injection hole that penetrates both surfaces of the end cap in the thickness direction, and the lower plastic also includes an injection through hole that penetrates both surfaces of the lower plastic in the thickness direction. The spacer also includes a clearance portion, which is disposed on one side edge of the spacer in the length direction of the end cap assembly, and the clearance portion extends through both surfaces of the spacer in the thickness direction. Along the thickness direction of the end cap assembly, the projections of the injection hole and the injection through hole are both completely located within the projection of the clearance portion, and the injection hole and the injection through hole are coaxially arranged and connected.

4. The end cap assembly according to claim 1, characterized in that, The end cap includes a mounting groove recessed on the surface of the end cap facing the lower plastic. The mounting groove includes a first sub-groove and a second sub-groove, the second sub-groove being connected to and communicating with the first sub-groove along the length of the end cap assembly. At least a portion of the spacer is located within the first sub-groove and the second sub-groove.

5. The end cap assembly according to claim 4, characterized in that, The lower plastic also includes a mounting protrusion and a supporting protrusion. The mounting protrusion protrudes from the surface of the lower plastic facing the end cap, and the mounting protrusion includes a mounting surface facing the end cap. The supporting protrusion protrudes from the mounting surface of the mounting protrusion, and the supporting protrusion includes a supporting surface, which faces the same direction as the mounting surface. Both the mounting protrusion and the supporting protrusion are located within the first sub-groove, and the supporting surface of the supporting protrusion faces the bottom surface of the first sub-groove.

6. The end cap assembly according to claim 5, characterized in that, The lower plastic also includes a first limiting groove and a second limiting groove. The first limiting groove is recessed on the surface of the lower plastic facing away from the end cap, and the second limiting groove is recessed on the bottom wall surface of the first limiting groove. The first limiting groove and the second limiting groove are respectively protruded on the surface of the lower plastic facing the end cap to form the mounting protrusion and the support protrusion. The connecting part has a limiting protrusion on its surface facing the main body, the connecting part is located in the first limiting groove, and the limiting protrusion is located in the second limiting groove.

7. The end cap assembly according to claim 5, characterized in that, The spacer further includes a first surface and a second surface, the first surface and the second surface being disposed opposite to each other along the thickness direction of the spacer, the second surface having a recessed portion and the first surface having a protruding portion, the recessed portion having a concave surface and the protruding portion having a convex surface; The first surface faces the end cap, the second surface faces the lower plastic, the protrusion is accommodated in the first sub-groove and the second sub-groove, the protrusion is connected to a portion of the bottom surface of the first sub-groove and a portion of the bottom surface of the second sub-groove, and the supporting surface of the supporting protrusion abuts against the concave surface.

8. The end cap assembly according to claim 3, characterized in that, The number of pole posts and spacers are both multiple, and each spacer corresponds to one pole post assembly. The multiple spacers may have the same or different structures, and at least one of the spacers is provided with the clearance portion.

9. An energy storage device, characterized in that, The energy storage device includes a housing, a battery cell, and an end cap assembly as described in any one of claims 1-8. The battery cell is housed within the housing, the end cap assembly is mounted at one end of the battery cell in the height direction, and the connecting portion of the electrode post is electrically connected to the electrode tab of the battery cell. The end cap assembly is sealed to the opening of the housing.

10. An energy storage system, characterized in that, The energy storage system includes the energy storage device as described in claim 9.

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