End cap assembly, energy storage device and residential energy storage system

Abstract

The application provides an end cover assembly, an energy storage device and a household energy storage system. The end cover assembly comprises a current collector and an end cover. The current collector is used for electrical connection with an electrode assembly. The central axis of the end cover coincides with the central axis of the current collector. The end cover comprises an end cover body and a first boss. The central axis of the end cover body coincides with the central axis of the first boss. The end cover body comprises a first surface arranged towards the current collector and a second surface arranged opposite to the first surface. The first boss is recessed relative to the second surface and is arranged protruding relative to the first surface. The orthographic projection of the current collector on the end cover completely covers the first boss. The technical scheme of the application can reduce the electrolyte between the current collector and the end cover and improve the utilization rate of the electrolyte.

Description

Technical Field

[0001] This application relates to the field of energy storage devices, and more particularly to an end cap assembly, an energy storage device, and a residential energy storage system. Background Technology

[0002] Currently, batteries generally consist of a cell, an end cap assembly, and a casing. The casing houses the cell, and the end cap assembly seals the cell with the casing. The end cap assembly typically includes a current collector and an end cap. Excessive electrolyte tends to accumulate in the gap between the current collector and the end cap. This portion of electrolyte cannot participate in the battery's charging and discharging reactions, resulting in low electrolyte utilization. Summary of the Invention

[0003] Embodiments of this application provide an end cap assembly, an energy storage device, and a residential energy storage system, which can reduce the electrolyte between the current collector and the end cap and improve the utilization rate of the electrolyte.

[0004] In a first aspect, this application provides an end cap assembly, comprising:

[0005] Current collector, the current collector being used for electrical connection with the electrode assembly; and

[0006] An end cap, the central axis of which coincides with the central axis of the current collector, the end cap including an end cap body and a first boss, the central axis of the end cap body coinciding with the central axis of the first boss, the end cap body including a first surface facing the current collector and a second surface facing away from it, the first boss being recessed relative to the second surface and protruding relative to the first surface, the orthographic projection of the current collector on the end cap completely covering the first boss.

[0007] Understandably, a space is formed between the current collector and the end cap to accommodate the electrolyte. Currently, the electrolyte between the current collector and the end cap cannot contact the electrode assembly, resulting in waste of this portion of the electrolyte and reducing its utilization rate. The first protrusion on the first surface can reduce the space between the end cap and the current collector, thereby reducing the amount of electrolyte that can be retained in this space, thus reducing the volume of electrolyte that cannot contact the motor assembly, and improving the electrolyte utilization rate.

[0008] In one possible implementation, the first boss includes a first boss surface, which is recessed relative to the second surface. The depth H of the recess of the first boss surface relative to the second surface and the thickness H of the end cap satisfy the following relationship: 1 / 2 ≤ H 1 / H ≤ 4 / 5.

[0009] It is understandable that when the indentation of the first boss surface is large (4 / 5≤H1 / H), the other surface of the first boss protrudes relatively much from the end cap body. Therefore, the shape of the end cap is more irregular, which affects the structural strength of the end cap and thus affects the structural stability of the energy storage device using the end cap assembly.

[0010] When the indentation of the first boss is small (1 / 2 ≤ H1 / H), the convexity of the other surface of the first boss relative to the end cap body is also small. At this time, the size of the space between the end cap and the current collector changes little, and a large amount of electrolyte will still remain between the end cap and the current collector, which cannot effectively improve the utilization rate of the electrolyte.

[0011] In one possible implementation, the end cap further includes a second boss, which protrudes from the first boss surface relative to the first boss surface. The central axis of the second boss coincides with the central axis of the first boss surface. The second boss includes a first connecting surface facing away from the first boss surface, and the first connecting surface is recessed relative to the second surface.

[0012] Understandably, having the first connecting surface flush with the second surface improves the flatness of the end cap assembly. During welding of the first connecting surface to the module aluminum bar, the module aluminum bar can abut against both the first connecting surface and the second surface.

[0013] In one possible implementation, the end cap further includes a connecting hole that extends through the first boss and the second boss along the thickness direction of the end cap, and the central axis of the connecting hole coincides with the central axis of the first boss and the central axis of the second boss.

[0014] The current collector includes a current collector body and a protrusion. The protrusion is located on the surface of the current collector body facing the end cap. One end of the protrusion away from the current collector body passes through the connection hole. The surface of the protrusion away from the current collector body is flush with the first connection surface.

[0015] Understandably, having the protrusion of the current collector flush with the first connecting surface can make the appearance of the end cap assembly smoother, thereby increasing the flatness of the surface formed by the first connecting surface and the protrusion and the welding of the module aluminum bar.

[0016] In one possible implementation, the first boss includes a second boss surface disposed opposite to the first boss surface, the connecting hole penetrates the first boss surface and the second boss surface, the connecting hole includes a first hole and a second hole that are connected, the first hole and the second hole are disposed sequentially in the direction of the end cap toward the manifold, and the maximum radial dimension of the first hole is less than or equal to the minimum radial dimension of the second hole;

[0017] The protruding post includes a first post, a second post, and a third post. In the direction of the collecting body toward the end cap, the first post, the second post, and the third post are connected in sequence. The radial dimension of the first post is larger than the radial dimension of the second hole. The end of the first post away from the collecting body abuts against the surface of the second protrusion. The second post is located inside the second hole and abuts against the wall of the second hole. The third post is located inside the first hole and abuts against the wall of the first hole.

[0018] Understandably, the first column can abut against the second protrusion surface, thereby limiting the end cap in its thickness direction and preventing the end cap from squeezing the current collector body and causing damage to the structure of the current collector body.

[0019] The second column can abut against the wall of the second hole, thereby allowing the current collector to be electrically connected to the end cap. Because the wall of the second hole is inclined, the contact area between the second hole and the second column is large, which increases the stability of the electrical connection between the current collector and the end cap.

[0020] The third column can abut against the wall of the first hole, and the wall of the first hole can limit the third column in its circumferential direction, thereby increasing the connection stability between the collector and the end cap.

[0021] In one possible implementation, the end cap body includes a second connecting surface, which is disposed around the periphery of the first boss surface, and the second connecting surface connects between the second surface and the first boss surface.

[0022] The end cap is provided with a first thinning groove and a second thinning groove. Both the first thinning groove and the second thinning groove are recessed from the first boss surface. The first thinning groove is arranged around the periphery of the second boss, and the second thinning groove is arranged around the periphery of the first thinning groove and spaced apart from the first thinning groove.

[0023] Understandably, the first and second thinning grooves can form an annular explosion-proof valve. When the internal pressure of the energy storage device using the end cap assembly is too high, the pressure can break through the first and second thinning grooves. The protrusions in front of the first and second thinning grooves can be lifted up, thereby providing a pressure relief port for the gas or liquid inside the energy storage device and preventing an explosion due to excessive internal pressure.

[0024] In one possible implementation, the depth H1 of the recess of the first boss surface relative to the second surface is between 0.5 mm and 1.5 mm.

[0025] It is understandable that when the depth of the first boss's recess relative to the second surface is small (less than 0.5 mm), the distance the first boss protrudes relative to the first surface is also small. Therefore, the first boss cannot effectively reduce the space between the end cap and the current collector, resulting in a large amount of electrolyte remaining in the space between the end cap and the current collector.

[0026] When the depth of the first boss's recess relative to the second surface is large (greater than 1.5 mm), the protrusion distance of the first boss relative to the first surface is large. The first boss is more prone to stress concentration when subjected to impact force, which in turn leads to weaker structural strength of the end cap and makes it impossible to guarantee the structural stability of the end cap assembly.

[0027] In one possible implementation, the end cap further includes a connecting portion connected to the first surface, the connecting portion being disposed around the first boss, and a gap being present between the connecting portion and the first boss.

[0028] Understandably, the end cap assembly needs to cooperate with the housing of the energy storage device to form a housing space, and the connecting part can provide a connection position between the end cap assembly and the housing.

[0029] Secondly, this application also provides an energy storage device, including an electrode assembly and an end cap assembly as described above. The end cap assembly is located at the bottom end of the energy storage device. The current collector includes a protrusion and a current collector body. The protrusion is connected to the side of the current collector body opposite to the end cap, and the protrusion is connected to the electrode assembly.

[0030] Thirdly, this application provides a residential energy storage system, including an energy storage device with a load as described above, the energy storage device being used to supply power to the load. Attached Figure Description

[0031] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a residential energy storage system provided in the embodiments of this application;

[0033] Figure 2 yes Figure 1 A schematic diagram of the provided energy storage device;

[0034] Figure 3 yes Figure 2 The diagram shows the structure of a single cell.

[0035] Figure 4 yes Figure 3 The diagram shows a structural schematic of the current collector at one angle.

[0036] Figure 5 yes Figure 4 The diagram shows the structure of the current collector from another angle;

[0037] Figure 6 yes Figure 3 The diagram shows the structure of the end cap;

[0038] Figure 7 yes Figure 6 A cross-sectional schematic diagram of the end cap is shown;

[0039] Figure 8 yes Figure 2 The diagram shows the assembly of the current collector and the end cap.

[0040] Reference numerals: Energy storage system 1000, conversion device 100, one type of user load 200, another type of user load 300, energy storage device 400, module aluminum bar 410, multiple individual batteries 420, housing 421, end cap assembly 422, current collector 423, end cap 424, current collector body 4231, protrusion 4232, protrusion 4236, through hole 4237, abutment plate 4238, first pillar 4233, second pillar 4234, third pillar 4235, end cap body 4241, first boss 4242, and so on. Two bosses 4243, connecting part 4244, first surface 4245, second surface 4246, middle area 4247, edge area 4248, first boss surface 4251, second boss surface 4252, second connecting surface 4249, depth H1 of the first boss surface 4251 recessed relative to the second surface 4246, thickness H of end cap 424, first thinning groove 4253, second thinning groove 4254, first connecting surface 4255, peripheral side surface 4256, connecting hole 4257, first hole 4258, second hole 4259. Detailed Implementation

[0041] For ease of understanding, the terminology used in the embodiments of this application will be explained first.

[0042] And / or: This is simply a way of describing the relationship between related objects. It indicates that there can be three kinds of relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0043] Multiple: refers to two or more.

[0044] Connection: should be interpreted broadly. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through an intermediary.

[0045] The specific embodiments of this application will now be clearly described in conjunction with the accompanying drawings.

[0046] Because the energy we need is highly time- and space-dependent, in order to utilize energy rationally and improve its efficiency, we need a medium or device 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. As we all know, to achieve the grand goal of carbon neutrality, the main way to generate green electricity is currently through the development of green energy sources such as photovoltaics and wind power to replace fossil fuels.

[0047] Currently, the generation of green electricity generally relies on solar, wind, and hydropower. However, wind and solar power are generally characterized by strong intermittency and large fluctuations, which can cause grid instability, insufficient power during peak demand periods, and excessive power during off-peak periods. Unstable voltage can also damage the power grid. Therefore, insufficient electricity demand or grid capacity may lead to the problem of "wind and solar curtailment." 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 electricity 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.

[0048] Taking electrochemical energy storage as an example, this solution provides an energy storage device. The energy storage device is equipped with a chemical battery, which mainly uses the chemical elements in the chemical battery as the energy storage medium. The charging and discharging process is accompanied by the chemical reaction or change of the energy storage medium. Simply put, the electrical energy generated by wind and solar energy is stored in the chemical battery. 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.

[0049] Current energy storage applications are quite widespread, including generation-side energy storage, grid-side energy storage, renewable energy grid-connected energy storage, and user-side energy storage. The corresponding types of energy storage devices include:

[0050] (1) Large energy storage containers used in grid-side energy storage scenarios can serve as high-quality active and reactive power regulation power sources in the grid, enabling load matching of electrical energy in time and space, enhancing the absorption capacity of renewable energy, and playing a significant role in grid system backup, alleviating peak load power supply pressure, and peak regulation and frequency regulation.

[0051] (2) Small and medium-sized energy storage cabinets used in commercial and industrial energy storage scenarios (banks, shopping malls, etc.) and small household energy storage boxes used in residential energy storage scenarios primarily operate under the "peak shaving and valley filling" mode. Because there are significant price differences in electricity during peak and off-peak periods based on demand, users with energy storage devices typically charge the cabinets / boxes during off-peak periods and release the electricity during peak periods to save on costs. Furthermore, in remote areas and regions prone to natural disasters such as earthquakes and hurricanes, the presence of household energy storage devices effectively provides backup power for users and the power grid, eliminating the inconvenience caused by frequent power outages due to disasters or other reasons.

[0052] This application uses a residential energy storage scenario in user-side energy storage as an example for illustration. Please refer to [link / reference]. Figure 1 , Figure 1 This is the residential energy storage system 1000 provided in the embodiments of this application.

[0053] The residential energy storage system 1000 includes a power conversion device 100 (photovoltaic panel), a user load 200 (streetlight), another user load 300 (household appliance), and an energy storage device 400. The energy storage device 400 is a small energy storage box that can be wall-mounted to an outdoor wall. Specifically, the photovoltaic panel converts solar energy into electricity during periods of low electricity prices, and the energy storage device 400 stores this electricity and supplies it to streetlights and household appliances during peak electricity prices, or provides power during grid outages. It should be noted that the energy storage device 400 in this application is not limited to residential energy storage scenarios.

[0054] Please see Figure 2 , Figure 2 yes Figure 1 A schematic diagram of the provided energy storage device 400 is shown. The energy storage device 400 may include a module aluminum bar 410 and multiple individual cells 420. The multiple individual cells 420 are arranged in an array, and the module aluminum bar 410 can be welded to the electrodes of the individual cells 420, thereby connecting the multiple individual cells 420 in series or in parallel.

[0055] Currently, a single-cell battery typically includes an end cap assembly, a housing, an electrode assembly, and an electrolyte. The end cap assembly can be sealed to the housing to form a containment space. The electrode assembly and electrolyte can be located within the containment space, and the electrode assembly can be immersed in the electrolyte. The end cap assembly generally includes a current collector and an end cap. Excessive electrolyte tends to accumulate in the gap between the current collector and the end cap. This portion of electrolyte cannot participate in the battery's charge and discharge reactions, resulting in low electrolyte utilization.

[0056] Based on this, embodiments of this application provide a single-cell battery that can reduce the amount of electrolyte between the current collector and the end cap, thereby improving the utilization rate of the electrolyte.

[0057] Please see Figure 3 , Figure 3 yes Figure 2 The diagram shows the structure of a single-cell battery 420. The single-cell battery 420 includes a housing 421, an electrode assembly (not shown), an electrolyte (not shown), and an end cap assembly 422. The housing 421 may be cylindrical, with an opening at one end. The electrode assembly is installed inside the housing 421. The electrolyte is located within a sealed space formed by the housing 421 and the end cap assembly 422, and the electrode assembly is immersed in the electrolyte. Along the height direction of the single-cell battery 420, the end cap assembly 422 is connected to the opening of the housing 421 and is electrically connected to the electrode assembly. Exemplarily, when the single-cell battery 420 is placed in its operating environment, the end cap assembly 422 may be located at the bottom end of the single-cell battery 420.

[0058] It is understandable that when the end cap assembly 422 is located at the bottom of the single cell 420, by configuring the internal space in the end cap assembly 422, the volume of electrolyte idle in the end cap assembly 422 can be reduced, so that more electrolyte can react with the electrode assembly located above the end cap assembly 422, thereby improving the utilization rate of electrolyte.

[0059] Please refer to the following: Figure 3 The end cap assembly 422 includes a current collector 423 and an end cap 424. The current collector 423 and the end cap 424 are stacked. The central axis of the current collector 423 coincides with the central axis of the end cap 424. One side of the current collector 423 is electrically connected to the electrode assembly. The other side of the current collector 423, which is disposed opposite to it, is electrically connected to the end cap 424. The current collector 423 is located on the side of the end cap 424 facing the housing 421.

[0060] It should be noted that, Figure 3 The purpose is merely to schematically illustrate the connection relationship between the current collector 423 and the end cap 424, and is not to specifically limit the connection position, specific structure, or quantity of each device. Furthermore, the structure illustrated in the embodiments of this application does not constitute a specific limitation on the end cap assembly 422. In other embodiments of this application, the end cap assembly 422 may include... Figure 3 This may involve more or fewer components, or combining certain components, or splitting certain components, or different component arrangements. Figure 3 The components shown can be implemented in hardware, software, or a combination of both.

[0061] Please refer to the following: Figure 4 and Figure 5 , Figure 4 yes Figure 3The diagram shown is a structural schematic of the current collector 423 at one angle. Figure 5 yes Figure 4 The diagram shows a structural schematic of the current collector 423 from another angle. The current collector 423 includes a current collector body 4231 and a protrusion 4232. The protrusion 4232 is connected to one side surface of the current collector body 4231.

[0062] The collector also includes multiple protrusions 4236, multiple through holes 4237, and multiple abutment plates 4238. The protrusions 4236 are recessed on the side surface of the collector body 4231 where the protrusion 4232 is located. On the side of the collector body 4231 without the protrusion 4232, the corresponding positions of the protrusions 4236 protrude relative to the surface of the collector body 4231. There are three protrusions 4236, arranged circumferentially along the protrusion 4232. The included angle between two adjacent protrusions 4236 can be 60°. Each protrusion 4236 extends from the edge of the collector body 4231 towards the center.

[0063] It is understood that the protrusion 4236 is provided on the surface of the current collector 4231 in the direction of the electrode assembly of the single cell 420. Therefore, the protrusion 4236 can be welded to the electrode assembly, thereby realizing the electrical connection between the current collector 423 and the electrode assembly.

[0064] Through holes 4237 penetrate the current collecting body 4231 along its thickness direction. Through holes 4237 and protrusions 4236 are spaced apart. Multiple through holes 4237 are arranged in an array. For example... Figure 4 As shown, a region is formed between every two protrusions 4236. The three protrusions 4236 divide the current collecting body 4231 into three regions. Multiple through holes 4237 can be evenly distributed in the three regions.

[0065] Understandably, the through-hole 4237 allows gas or liquid from the individual battery 420 to pass through. When the internal pressure of the individual battery 420 becomes too high, the gas and / or liquid inside the individual battery 420 first pass through the through-hole 4237, and then force open the explosion-proof valve on the end cover 424 to release pressure and prevent the individual battery 420 from exploding.

[0066] In addition, as the fluid passes through the through hole 4237 of the current collector 423, the current collector body 4231 can intercept the fragments of the internal components of the single cell 420 that flow with the fluid, preventing the fragments from passing through the current collector body 4231 and accumulating at the explosion-proof valve of the end cover 424, which would cause the explosion-proof valve to be blocked and fail.

[0067] Multiple abutment plates 4238 can be connected to the periphery of the collector body 4231. The multiple abutment plates 4238 are spaced apart. The abutment plates 4238 are spaced apart from the protrusions 4236. The abutment plates 4238 extend from the periphery of the collector body 4231 toward the side of the collector body 4231 where the protrusions 4232 are provided. For example, there can be nine abutment plates 4238. Every three abutment plates 4238 can be located at the edge of an area formed by two adjacent protrusions 4236.

[0068] Understandably, when the current collector 423 is pressed towards the end cover 424 by the electrode assembly (e.g., when the battery is dropped), the abutment plate 4238 can abut against the surface of the end cover 424 facing the current collector 423. This buffers the external force and prevents the current collector 423 from deforming after being impacted, ultimately causing the single cell 420 to fail.

[0069] The protruding post 4232 includes a first post 4233, a second post 4234, and a third post 4235, which are connected sequentially. One side of the first post 4233 is connected to the current collecting body 4231, and the first post 4233 can be connected to the center of the current collecting body 4231. The other side of the first post 4233, away from the current collecting body 4231, is connected to the second post 4234. In the thickness direction of the current collecting member 423, the radial dimension of the first post 4233 can remain unchanged. That is, the shape of the first post 4233 can be cylindrical.

[0070] The second column 4234 is connected to the end face of the first column 4233 away from the current collecting body 4231. The radial dimension of the side of the second column 4234 connected to the first column 4233 can be smaller than the radial dimension of the first column 4233. The maximum radial dimension of the second column 4234 is smaller than the minimum radial dimension of the first column 4233. The radial dimension of the second column 4234 gradually decreases in the direction away from the first column 4233. The rate of change of the radial dimension of the second column 4234 can be a first rate. For example, the shape of the second column 4234 can be a frustum. The circumferential surface of the second column 4234 can be the circumferential surface of a frustum.

[0071] The third column 4235 is connected to the end face of the second column 4234 away from the first column 4233. The radial dimension of the side of the third column 4235 connected to the second column 4234 can be the same as the radial dimension of the second column 4234. The radial dimension of the third column 4235 can gradually decrease in the direction away from the second column 4234. The rate of change of the radial dimension of the third column 4235 can be a second rate. The second rate can be less than the first rate. For example, the shape of the third column 4235 can be a frustum. The circumferential surface of the third column 4235 can be the circumferential surface of a frustum. Alternatively, the third column 4235 can also be a cylinder, and the circumferential surface of the third column 4235 can be the circumferential surface of a cylinder. That is, the radial dimension of the third column 4235 can always remain unchanged.

[0072] Please refer to the following: Figure 6 and Figure 7 , Figure 6 yes Figure 3 The diagram shown is a structural schematic of the end cap 424. Figure 7 yes Figure 6 The diagram shows a cross-sectional view of the end cap 424. The end cap 424 includes an end cap body 4241, a first boss 4242, a second boss 4243, and a connecting portion 4244. The central axis of the end cap body 4241, the central axis of the first boss 4242, the central axis of the second boss 4243, and the central axis of the connecting portion 4244 all coincide.

[0073] The end cap body 4241 includes a first surface 4245 and a second surface 4246 disposed opposite to each other along its thickness direction. The first surface 4245 is the surface of the end cap body 4241 facing the current collector 423, and the second surface 4246 is the surface of the end cap body 4241 facing away from the current collector 423. The end cap body 4241 also includes a central region 4247 and an edge region 4248. The edge region 4248 is disposed around the central region 4247 and connected to the central region 4247.

[0074] The first boss 4242 is connected to the first surface 4245 of the end cap body 4241 and is located in the middle region 4247 of the end cap body 4241. The first boss 4242 protrudes from the first surface 4245 and is recessed from the second surface 4246.

[0075] Understandably, a space for containing electrolyte is formed between the current collector 423 and the end cap 424. Currently, the electrolyte between the current collector 423 and the end cap 424 cannot contact the electrode assembly, resulting in waste of this portion of electrolyte and reducing electrolyte utilization. The first protrusion 4242 provided on the first surface 4245 can reduce the space between the end cap 424 and the current collector 423, thereby reducing the amount of electrolyte that can be retained in this space, thus reducing the volume of electrolyte that cannot contact the motor assembly and improving electrolyte utilization.

[0076] The first boss 4242 includes a first boss surface 4251 and a second boss surface 4252 disposed opposite to each other along the thickness direction. The first boss surface 4251 is the surface of the first boss 4242 facing the end cap body 4241, and the first boss surface 4251 is recessed relative to the second surface 4246. The first boss surface 4251 may be disposed parallel to the second surface 4246. The second boss surface 4252 is the surface of the first boss 4242 away from the end cap body 4241, and the second boss surface 4252 is protruding relative to the first surface 4245.

[0077] The end cap body 4241 also includes a second connecting surface 4249, which surrounds the periphery of the first boss surface 4251 and connects the second surface 4246 and the first boss surface 4251. The second connecting surface 4249 is set at an angle to the second surface 4246. For example, the angle between the second connecting surface 4249 and the second surface 4246 can be an obtuse angle. In other words, the first boss surface 4251 and the second surface 4246 are connected by the second connecting surface 4249. The first boss surface 4251 and the second connecting surface 4249 are set at an angle. For example, the depth H1 of the recess of the first boss surface 4251 relative to the second surface 4246 and the thickness H of the end cap 424 satisfy the relationship: 1 / 2 ≤ H1 / H ≤ 4 / 5. The depth H1 of the recess of the first boss surface 4251 relative to the second surface 4246 is between 0.5mm and 1.5mm (including the endpoint values ​​of 0.5mm and 1.5mm).

[0078] It is understandable that when the degree of concavity of the first boss surface 4251 is large (4 / 5≤H1 / H), and / or when the depth of concavity of the first boss surface 4251 relative to the second surface 4246 is large (greater than 1.5mm), the degree of protrusion of the second boss surface 4252 of the first boss 4242 relative to the end cap body 4241 is large. At this time, the shape of the end cap 424 is relatively irregular, which affects the structural strength of the end cap 424, thereby affecting the structural stability of the energy storage device 400 using the end cap assembly 422.

[0079] When the degree of recess of the first boss 4242 is small (1 / 2 ≤ H1 / H), and / or when the depth of the recess of the first boss surface 4251 relative to the second surface 4246 is small (less than 0.5 mm), the degree of protrusion of the second boss surface 4252 of the first boss 4242 relative to the end cap body 4241 is small. In this case, the change in the size of the space between the end cap 424 and the current collector 423 is small, and a relatively large amount of electrolyte will still remain between the end cap 424 and the current collector 423, failing to effectively improve the utilization rate of the electrolyte.

[0080] The ratio of the depth H1 of the first protrusion surface 4251 recessed relative to the second surface 4246 to the thickness H of the end cap 424 is between 1 / 2 and 4 / 5 (including the endpoint values ​​of 1 / 2 and 4 / 5), and / or the depth H1 of the first protrusion surface 4251 recessed relative to the second surface 4246 is between 0.5mm and 1.5mm (including the endpoint values ​​of 0.5mm and 1.5mm). This not only reduces the electrolyte trapped between the end cap 424 and the current collector 423, but also ensures the structural strength of the end cap assembly 422, so that the structural strength of the end cap assembly 422 meets the usage requirements of the single cell 420.

[0081] Please refer to the following: Figure 7 The end cap 424 is also provided with a first thinning groove 4253 and a second thinning groove 4254, both of which are recessed from the first boss surface 4251. The first thinning groove 4253 and the second thinning groove 4254 are both arranged around the center of the first boss 4242. The first thinning groove 4253 is arranged around the periphery of the second boss 4243 (described below). The second thinning groove 4254 is arranged around the periphery of the first thinning groove 4253. The second thinning groove 4254 is located near the second connecting surface 4249 of the end cap body 4241. The first thinning groove 4253 and the second thinning groove 4254 are spaced apart.

[0082] Understandably, the first thinning groove 4253 and the second thinning groove 4254 can thin the material of the first boss 4242 at its location, thereby weakening the structural strength of the first boss 4242 at that location. The first thinning groove 4253 and the second thinning groove 4254 can be formed during the stamping of the end cap 424. The first thinning groove 4253 and the second thinning groove 4254 can form an annular explosion-proof valve structure. The explosion-proof valve structure is misaligned with the second surface 4246 of the end cap 424, preventing accidental scratches to the explosion-proof valve structure by external objects. When the internal pressure of the energy storage device 400 using the end cap assembly 422 is too high, the pressure can break through the first thinning groove 4253 and / or the second thinning groove 4254. The first protrusion 4242 between the first thinning groove 4253 and the second thinning groove 4254 can be lifted up, thereby providing a pressure relief port for the gas or liquid inside the single cell 420, and preventing the single cell 420 from exploding due to excessive pressure.

[0083] Please continue reading. Figure 7 The second boss 4243 is connected to the first boss surface 4251. The second boss 4243 protrudes relative to the first boss surface 4251, and the protrusion direction of the second boss 4243 is opposite to the protrusion direction of the first boss 4242. The second boss 4243 includes a first connecting surface 4255 and a peripheral surface 4256. The first connecting surface 4255 is the surface of the second boss 4243 that faces away from the first boss surface 4251. The first connecting surface 4255 can be flush with the second surface 4246. The peripheral surface 4256 of the second boss 4243 can be the peripheral surface 4256 of a frustum, and the cross-sectional diameter of the peripheral surface 4256 of the second boss 4243 can decrease sequentially from the first boss surface 4251 toward the direction away from the first boss surface 4251. For example, the second boss 4243 may also be recessed from the second boss surface 4252 of the first boss 4242 and protrude relative to the first boss surface 4251 of the first boss 4242. The thickness of the second boss 4243 may be the same as the thickness of the first boss 4242.

[0084] Understandably, having the first connecting surface 4255 flush with the second surface 4246 can improve the flatness of the end cap assembly 422. When the first connecting surface 4255 is welded to the module aluminum bar 410, the module aluminum bar 410 can abut against the first connecting surface 4255 and the second surface 4246.

[0085] In other possible embodiments, the first connecting surface 4255 may also be recessed relative to the second surface 4246. It is understood that after the first connecting surface 4255 is soldered to the electrode assembly, it may be partially covered by solder. The solder-covered first connecting surface 4255 can be flush with the second surface 4246, resulting in a smoother appearance for the end cap assembly 422. The end cap 424 also has a connecting hole 4257, which extends through the first boss 4242 and the second boss 4243 along the thickness direction of the end cap 424. The central axis of the connecting hole 4257 may coincide with the central axis of the first boss 4242 and the second boss 4243. Specifically, the connecting hole 4257 extends through the first boss surface 4251 and the second boss surface 4252 of the first boss 4242, and the first connecting surface 4255 of the second boss 4243.

[0086] The connecting hole 4257 includes a first hole 4258 and a second hole 4259 that are connected. The first hole 4258 and the second hole 4259 are sequentially arranged in the direction from the end cap 424 toward the collector 423. The first hole 4258 penetrates the first connecting surface 4255. In the direction away from the collector body 4231, the radial dimension of the first hole 4258 can gradually decrease, and the radial dimension of the first hole 4258 can decrease at a first rate. Alternatively, in the direction away from the collector body 4231, the radial dimension of the first hole 4258 can remain unchanged.

[0087] The second hole 4259 penetrates the first boss surface 4251 and the second boss surface 4252. The minimum radial dimension of the second hole 4259 can be equal to the maximum radial dimension of the first hole 4258. The radial dimension at the intersection of the hole wall of the second hole 4259 and the hole wall of the first hole 4258 is the minimum radial dimension of the second hole 4259 and the maximum radial dimension of the first hole 4258. In the direction away from the current collecting body 4231, the radial dimension of the second hole 4259 gradually decreases. The radial dimension of the second hole 4259 can gradually decrease at a second rate, where the first rate is less than the second rate.

[0088] The connecting portion 4244 is connected to the first surface 4245 and protrudes from the first surface 4245. The connecting portion 4244 is located in the edge region 4248 and is disposed around the first boss 4242, with a gap between the connecting portion 4244 and the first boss 4242. Furthermore, the side of the connecting portion 4244 away from the first boss 4242 can be recessed relative to the outer periphery of the end cap body 4241.

[0089] Understandably, the end cap assembly 422 needs to cooperate with the housing 421 of the energy storage device 400 to form a receiving space. The connecting portion 4244 can provide a connection position between the end cap assembly 422 and the housing 421. The side of the connecting portion 4244 away from the first boss 4242 can abut against the inner wall of the housing 421.

[0090] Please see Figure 8 , Figure 8 yes Figure 2 The diagram shows the assembly of the current collector 423 and the end cap 424. The first surface 4245 of the end cap 424 faces the current collector 423. That is, the second boss surface 4252 of the first boss 4242 faces the current collector 423. The orthographic projection of the current collector 423 on the end cap 424 completely covers the first boss 4242.

[0091] The manifold 423 has a protrusion 4232 on one side facing the first surface 4245 of the end cap body 4241. The end of the protrusion 4232 of the manifold 423 away from the manifold body 4231 passes through the connecting hole 4257. The surface of the protrusion 4232 away from the manifold body 4231 is flush with the first connecting surface 4255. The first column 4233 of the protrusion 4232 abuts against the second boss surface 4252. The second column 4234 of the protrusion 4232 is located within the second hole 4259, and its peripheral side abuts against the hole wall of the second hole 4259. The third column 4235 of the protrusion 4232 is located within the first hole 4258. The peripheral side of the third column 4235 abuts against the hole wall of the first hole 4258.

[0092] It is understandable that the end face of the first column 4233 of the protrusion 4232 can abut against the second protrusion surface 4252, thereby limiting the end cap 424 in its thickness direction and preventing the end cap 424 from squeezing the current collector body 4231 and causing damage to the structure of the current collector body 4231.

[0093] The second post 4234 of the protrusion 4232 can abut against the wall of the second hole 4259, thereby allowing the current collector 423 to be electrically connected to the end cap 424. Because the wall of the second hole 4259 is inclined, the contact area between the second hole 4259 and the second post 4234 is larger, which increases the stability of the electrical connection between the current collector 423 and the end cap 424.

[0094] The third column 4235 of the protruding column 4232 can abut against the wall of the first hole 4258. The wall of the first hole 4258 can limit the third column 4235 in its circumferential direction, thereby increasing the connection stability between the current collector 423 and the end cap 424 and realizing the uniformity of current collection by the current collector 423.

[0095] The connecting portion 4244 is fixedly connected to the opening of the housing 421. For example, the side of the connecting portion 4244 away from the first boss 4242 can be welded to the opening of the housing 421, thereby sealing the end cap assembly 422 to the housing 421.

[0096] In the energy storage device 400, multiple individual cells 420 can be arranged in an array, and the second surface 4246 of the end cap 424, the second connecting surface 4249 of the second boss 4243, and the surface of the protrusion 4232 of the current collector 423 of each individual cell 420 can be electrically connected to the module aluminum bar 410 of the energy storage device 400, thereby enabling the multiple individual cells 420 to be connected in series or in parallel.

[0097] Understandably, the flush alignment of the protrusion 4232 of the manifold 423 with the first connecting surface 4255 can make the surface of the end cap assembly 422 smoother, thereby increasing the flatness of the surface formed by the first connecting surface 4255 and the protrusion 4232 with the welding of the module aluminum bar 410.

[0098] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An end cap assembly (422), characterized in that, include: Current collector (423), said current collector (423) being used for electrical connection with electrode assembly; and End cap (424), the end cap (424) includes an end cap body (4241) and a first boss (4242), the central axes of the end cap body (4241), the collector (423) and the first boss (4242) are coincident, the end cap body (4241) includes a first surface (4245) disposed towards the collector (423) and a second surface (4246) disposed opposite to it, the first boss (4242) is recessed relative to the second surface (4246) and relative to the first boss (4242) A surface (4245) is protruding, and the orthographic projection of the current collector (423) on the end cap (424) completely covers the first boss (4242). The first boss (4242) includes a first boss surface (4251), which is recessed relative to the second surface (4246). The depth H1 of the recess of the first boss surface (4251) relative to the second surface (4246) satisfies the relationship H of the thickness H of the end cap (424): 1 / 2≤H1 / H≤4 / 5.

2. The end cap assembly (422) according to claim 1, characterized in that, The end cap (424) further includes a second boss (4243), which protrudes from the first boss surface (4251) of the first boss (4242). The central axis of the second boss (4243) coincides with the central axis of the first boss (4242). The second boss (4243) includes a first connecting surface (4255) facing away from the first boss surface (4251). The first connecting surface (4255) is recessed relative to the second surface (4246).

3. The end cap assembly (422) according to claim 2, characterized in that, The end cap (424) further includes a connecting hole (4257), which penetrates the first boss (4242) and the second boss (4243) along the thickness direction of the end cap (424). The central axis of the connecting hole (4257) coincides with the central axis of the first boss (4242) and the central axis of the second boss (4243). The current collector (423) includes a current collector body (4231) and a protrusion (4232). The protrusion (4232) is located on the surface of the current collector body (4231) facing the end cap (424). One end of the protrusion (4232) away from the current collector body (4231) passes through the connection hole (4257). The surface of the protrusion (4232) away from the current collector body (4231) is flush with the first connection surface (4255).

4. The end cap assembly (422) according to claim 3, characterized in that, The first boss (4242) includes a second boss surface (4252) disposed opposite to the first boss surface (4251). The connecting hole (4257) penetrates the first boss surface (4251) and the second boss surface (4252). The connecting hole (4257) includes a first hole (4258) and a second hole (4259) that are connected. In the direction of the end cap (424) toward the collector (423), the first hole (4258) and the second hole (4259) are arranged in sequence. The maximum radial dimension of the first hole (4258) is less than or equal to the minimum radial dimension of the second hole (4259). The protruding post (4232) includes a first post (4233), a second post (4234), and a third post (4235). In the direction of the collecting body (4231) toward the end cap (424), the first post (4233), the second post (4234), and the third post (4235) are connected in sequence. The radial dimension of the first post (4233) is larger than the radial dimension of the second hole (4259). The end of the first post (4233) away from the collecting body (4231) abuts against the second protruding surface (4252). The second post (4234) is located inside the second hole (4259) and abuts against the hole wall of the second hole (4259). The third post (4235) is located inside the first hole (4258) and abuts against the hole wall of the first hole (4258).

5. The end cap assembly (422) according to any one of claims 2-4, characterized in that, The end cap body (4241) includes a second connecting surface (4249), which is disposed around the periphery of the first boss surface (4251) and is connected between the second surface (4246) and the first boss surface (4251). The end cap (424) is provided with a first thinning groove (4253) and a second thinning groove (4254). Both the first thinning groove (4253) and the second thinning groove (4254) are recessed from the first boss surface (4251). The first thinning groove (4253) is arranged around the periphery of the second boss (4243), and the second thinning groove (4254) is arranged around the periphery of the first thinning groove (4253) and spaced apart from the first thinning groove (4253).

6. The end cap assembly (422) according to claim 3, characterized in that, The depth H1 of the first boss surface (4251) recessed relative to the second surface (4246) is between 0.5mm and 1.5mm.

7. The end cap assembly (422) according to claim 6, characterized in that, The end cap (424) further includes a connecting portion (4244), which is connected to the first surface (4245). The connecting portion (4244) is disposed around the first boss (4242), and there is a gap between the connecting portion (4244) and the first boss (4242).

8. An energy storage device (400), characterized in that, The device includes an electrode assembly and an end cap assembly (422) as described in any one of claims 1-7, the end cap assembly (422) being located at one end of the energy storage device (400), the current collector (423) including a protrusion (4236) and a current collector body (4231), the protrusion (4236) being connected to the side of the current collector body (4231) opposite to the end cap (424), and the protrusion (4236) being connected to the electrode assembly.

9. A residential energy storage system (1000), characterized in that, The load (300) includes the energy storage device (400) as described in claim 8, the energy storage device (400) being used to supply power to the load (300).

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