Energy storage device and energy storage system

Abstract

The invention discloses an energy storage device and an energy storage system.The energy storage device comprises a shell, an end cover assembly, a pole column, a battery cell and an adapter, multiple layers of tabs of the battery cell comprise a middle tab, a first side tab and a second side tab, the first side tab and the second side tab are located on the two sides of the middle tab respectively and bent towards the middle tab, and the first side tab and the second side tab are bent towards the adapter. The first side surface of the adapter is electrically connected with the first side lug, the second side surface of the adapter is electrically connected with the pole, a rectangular coordinate system is established by taking the root of the second side lug as an original point, the thickness direction of the battery cell as an x axis and the extension direction of the lug as a y axis, and the coordinate of the root of any lug is (x, 0); the coordinate of the connection position of the first side lug is (a, b), the coordinate of the connection position is (c, d) when the multi-layer lug is bent to enable the first side face to face the battery cell, and ((a-x) 2 + b2)-{(c-x) 2 + d2} > 0.

Description

Technical Field

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

[0002] During the battery cell processing, an adapter is usually arranged on one side of the multi-layer tab of the battery cell, and the multi-layer tab is pressed onto the adapter and then welded to the adapter, thereby completing the assembly of the adapter and the multi-layer tab.

[0003] Since the related technology usually die-cuts the multi-layer pole ears into pole ears of the same height when die-cutting to form the pole ears, that is, the protruding height of each pole ear relative to the battery cell is the same, when welding, after the pole ears on one side of the multi-layer pole ears are pressed to the other side on the adapter, the ends of the multi-layer pole ears away from the battery cell will be uneven. For example, the ends of the multi-layer pole ears form a stepped structure with an increasing gradient in the direction close to the adapter, and the welding area of ​​the pole ear farthest from the adapter is greatly reduced. In order to ensure that the weld mark can fall on each pole ear and ensure the welding quality of the pole ears, it is necessary to use pole ears with a higher height, which will lead to an increase in the cost of the battery cell foil and an increase in the internal resistance of the pole ears, thereby affecting the battery cell performance. Summary of the invention

[0004] The embodiments of the present application disclose an energy storage device and an energy storage system, which can reduce the protruding height of the tab relative to the battery cell to reduce the cost of the battery cell foil, and reduce the internal resistance of the tab, thereby improving the battery cell performance; at the same time, it can also avoid pulling and tearing the tab.

[0005] In order to achieve the above objectives, in a first aspect, the present application discloses an energy storage device, the energy storage device comprising:

[0006] A housing having an inner cavity and an opening communicating with the inner cavity;

[0007] An end cover assembly, the end cover assembly is sealed and arranged at the opening, and the end cover assembly is provided with a through pole hole;

[0008] A pole, wherein the pole is inserted into the pole hole;

[0009] A battery cell, wherein the battery cell is arranged in the inner cavity, the battery cell comprises a battery cell body and a multi-layered pole ear arranged on the battery cell body, the multi-layered pole ear is arranged at intervals along the thickness direction of the battery cell, and the multi-layered pole ear comprises a middle pole ear, a first side pole ear and a second side pole ear, the first side pole ear and the second side pole ear are respectively located on both sides of the middle pole ear in the thickness direction of the battery cell, and the first side pole ear and the second side pole ear are respectively bent toward the middle pole ear; and,

[0010] Adapter, the adapter has opposite first and second sides, the first side is electrically connected to the first side lug, and the second side is electrically connected to the terminal post;

[0011] The multi-layer lug can be bent from a first state to a second state, wherein the first state is configured as a state where the multi-layer lug is not bent and the first side faces the battery cell body, and the second state is configured as a state where the multi-layer lug is bent and the first side faces the battery cell body;

[0012] Each lug has a root connected to the battery cell body, the first side lug has a connection position connected to the adapter. Taking the root of the second side lug as the origin, the thickness direction of the battery cell as the x-axis, and the extending direction of the lug as the y-axis to establish a rectangular coordinate system, the coordinate of the root of any lug is (x, 0). When the multi-layer lug is in the first state, the coordinate of the connection position is (a, b), and when the multi-layer lug is in the second state, the coordinate of the connection position is (c, d); wherein, ((a - x) 2 + b 2 ) - {(c - x) 2 + d 2} > 0.

[0013] In the energy storage device provided by the embodiment of the present application, by bending and pressing the first side lug and the second side lug on both sides of the middle lug towards the middle lug respectively, and then fitting and electrically connecting the first side of the adapter to the first side lug, compared with the method of only bending and pressing the second side lug towards the first side lug, the bending degree of the second side lug can be reduced, so that while the second side lug has enough welding area after bending, the height of each layer of lug can be reduced, especially the height of the second side lug, thereby reducing the cost of the battery cell foil material and the internal resistance of the lug, and improving the performance of the battery cell.

[0014] At the same time, the energy storage device also satisfies the following relational expression: ((a - x) 2 + b 2 ) - {(c - x) 2 + d 2}>0, wherein b, c, d, k, and x can all be obtained based on actual battery cell tests. The range of a can be calculated by calculating the above relationship, and the distance range between the connection position of the first side pole ear and its root in the thickness direction of the battery cell can be determined after the first side pole ear is bent toward the middle pole ear, thereby determining the degree of bending of the first side pole ear toward the middle pole ear, thereby avoiding excessive pulling of the first side pole ear when the multi-layer pole ears are bent to set the first side surface toward the battery cell, thereby avoiding excessive bending of the first side pole ear, and further avoiding the situation where the first side pole ear is pulled or torn when the multi-layer pole ears need to be bent to set the first side surface of the adapter toward the battery cell body, thereby ensuring the conductive reliability of the pole ear.

[0015] As an optional implementation, in an embodiment of the first aspect of the present application, the expansion rate of the battery core in the thickness direction thereof is k, wherein the energy storage device satisfies the following relationship:

[0016] ((ax) 2 +b 2 )-{(c-(1+k)x) 2 +d 2}>0.

[0017] When the energy storage device satisfies the following relationship: (ax) 2 +b 2 )-{(c-(1+k)x) 2 +d 2 When}>0, excessive pulling of the first side tab can be avoided when the battery cell expands, thereby avoiding the first side tab from being pulled or torn when the battery cell expands, thereby ensuring the conductive reliability of the tab.

[0018] As an optional implementation, in an embodiment of the first aspect of the present application, when the first side pole ear and the second side pole ear are not bent toward the middle pole ear, and the first side pole ear is not connected to the first side surface, the height of each pole ear protruding relative to the battery cell body is equal.

[0019] Such an arrangement can keep the protruding height of each pole tab relative to the battery cell body the same, without the need for special die-cutting of the pole tab, thereby helping to simplify the die-cutting process of the pole tab.

[0020] As an alternative implementation, in the embodiment of the first aspect of the present application, when neither the first side tab nor the second side tab is bent towards the middle tab, and the first side tab is not connected to the first side, the height by which the first side tab protrudes relative to the battery cell body is greater than the height by which the middle tab protrudes relative to the battery cell body, and / or the height by which the second side tab protrudes relative to the battery cell body is greater than the height by which the middle tab protrudes relative to the battery cell body.

[0021] With such a design, after the first side tab and the second side tab are respectively bent and pressed towards the middle tab, that is, after the multi-layer tabs are pressed and connected, the ends of the middle tab, the first side tab, and the second side tab away from the battery cell can be made flush. Compared with the way that the height of each tab is equal, the height of the middle tab can be reduced at least, which is beneficial to reducing the cost of the battery cell foil material and the internal resistance of the tab, so that the performance of the battery cell can be improved.

[0022] As an alternative implementation, in the embodiment of the first aspect of the present application, when neither the first side tab nor the second side tab is bent towards the middle tab, and the first side tab is not connected to the first side, the height by which the tab protrudes relative to the battery cell body first decreases and then increases along the thickness direction of the battery cell.

[0023] With such a setting, after the first side tab and the second side tab are respectively bent and pressed towards the middle tab, that is, after the multi-layer tabs are pressed and connected, the ends of each layer of tabs away from the battery cell can be made flush. This can not only improve the aesthetic degree and the fixing firmness of the tabs, but also reduce the height of the tabs compared with the way that the height of each tab is equal, which is beneficial to reducing the cost of the battery cell foil material and the internal resistance of the tab, so that the performance of the battery cell can be improved.

[0024] As an alternative implementation, in the embodiment of the first aspect of the present application, when neither the first side tab nor the second side tab is bent towards the middle tab, and the first side tab is not connected to the first side, the distance between any two adjacent layers of the tabs is equal, which can arrange each layer of tabs at equal intervals, thus being beneficial to ensuring the charge and discharge performance and the comprehensive performance of the battery cell.

[0025] As an alternative implementation, in the embodiment of the first aspect of the present application, when neither the first side tab nor the second side tab is bent towards the middle tab, and the first side tab is not connected to the first side, the height difference between any two adjacent layers of the tabs protruding relative to the battery cell body is equal.

[0026] With such a setting, not only can the multi-layer tabs be made flatter after lamination, but also the heights of the multi-layer tabs protruding relative to the battery cell body are arranged in an arithmetic progression, forming a regular change. Therefore, it is convenient for die-cutting and forming of each layer of tabs, and precise control of the heights of each layer of tabs can be achieved.

[0027] As an optional implementation manner, in the embodiment of the first aspect of the present application, the energy storage device is a polygonal battery or a cylindrical battery. It can be seen that the energy storage device in the present application is not limited to a battery of a specific shape, and the shape of the energy storage device is diverse and flexible.

[0028] As an optional implementation manner, in the embodiment of the first aspect of the present application, the pole post holes include a first pole post hole and a second pole post hole;

[0029] The pole posts include a positive pole post and a negative pole post. The positive pole post passes through the first pole post hole, and the negative pole post passes through the second pole post hole;

[0030] The battery cell includes a first battery cell and a second battery cell. The first battery cell includes a first battery cell body, a first positive tab and a first negative tab arranged on the first battery cell body. The second battery cell includes a second battery cell body, a second positive tab and a second negative tab arranged on the second battery cell body. The first battery cell body and the second battery cell body both include the battery cell body. The first positive tab, the first negative tab, the second positive tab and the second negative tab all include the multi-layer tabs;

[0031] Wherein, the first battery cell and the second battery cell are arranged along the thickness direction of the battery cell. Along the thickness direction of the battery cell, the first positive tab and the second positive tab are arranged oppositely, and the first negative tab and the second negative tab are arranged oppositely, and / or, along the thickness direction of the battery cell, the first positive tab and the first negative tab are located on a side of the first battery cell body facing away from the second battery cell body, and the second positive tab and the second negative tab are located on a side of the second battery cell body facing away from the first battery cell body;

[0032] The adapter includes a first adapter component and a second adapter component. The first adapter component is electrically connected to the positive pole post, the first positive tab and the second positive tab respectively. The second adapter component is electrically connected to the negative pole post, the first negative tab and the second negative tab respectively.

[0033] It can be understood that during the assembly process of the battery cells, the first battery cell and the second battery cell are arranged along the height direction of the battery cell. And in the height direction of the battery cell, the first negative tab of the first battery cell and the second negative tab of the second battery cell can be arranged opposite to each other, and the first positive tab of the first battery cell and the second positive tab of the second battery cell can be arranged opposite to each other. This facilitates the welding of the first transfer component to the first positive tab and the second positive tab, as well as the welding of the second transfer component to the first negative tab and the second negative tab, which is conducive to realizing the welding of the first transfer piece to the first positive tab and the second positive tab, quickly realizing the welding of the second transfer component to the first negative tab and the second negative tab, and saving welding time.

[0034] In addition, since both the first positive tab of the first battery cell and the second positive tab of the second battery cell are located outside the battery cell, and both the first negative tab of the first battery cell and the second negative tab of the second battery cell are located outside the battery cell, when the first battery cell and the second battery cell are arranged along the thickness direction of the battery cell, the positions of the first positive tab and the second positive tab are far apart, and the positions of the first negative tab and the second negative tab are far apart. This can avoid the short circuit caused by the overlapping of the first positive tab and the second positive tab, and the short circuit caused by the overlapping of the first negative tab and the second negative tab. At the same time, it can ensure that both the first positive tab and the second positive tab have a large connection area with the first transfer component, and both the first negative tab and the second negative tab have a large connection area with the second transfer component. Therefore, it is beneficial to improve the connection strength between the battery cell and the transfer piece, and avoid the problem of conductive failure caused by too low connection strength between the battery cell and the transfer piece.

[0035] In the second aspect, the present application discloses an energy storage system, and the energy storage system has the energy storage device as described in the first aspect above. The energy storage system with the energy storage device described in the first aspect can also reduce the height of the tabs protruding relative to the battery cell, so as to reduce the cost of the battery cell foil and the internal resistance of the tabs, thereby improving the performance of the battery cell; at the same time, it can also avoid pulling and tearing the tabs.

[0036] Compared with the prior art, the beneficial effects of the present application are as follows:

[0037] The energy storage device and the energy storage system provided by the embodiments of the present application, by bending and pressing the first side tab and the second side tab on both sides of the middle tab towards the middle tab respectively, and then fitting and electrically connecting the first side of the transfer piece to the first side tab, compared with the method of only bending and pressing the second side tab towards the first side tab, can reduce the bending degree of the second side tab. Thus, while enabling the second side tab to have a sufficient welding area after bending, it can reduce the height of each layer of tabs, especially the height of the second side tab. Furthermore, it can reduce the cost of the battery cell foil and the internal resistance of the tabs, so that the performance of the battery cell can be improved.

[0038] At the same time, the energy storage device also satisfies the following relationship: ((a - x)2 +b 2 )-{(cx) 2 +d 2}>0, wherein b, c, d, k, and x can all be obtained based on actual battery cell tests. The range of a can be calculated by calculating the above relationship, and the distance range between the connection position of the first side pole ear and its root in the thickness direction of the battery cell can be determined after the first side pole ear is bent toward the middle pole ear, thereby determining the degree of bending of the first side pole ear toward the middle pole ear, thereby avoiding excessive pulling of the first side pole ear when the multi-layer pole ears are bent to set the first side face toward the battery cell, thereby avoiding excessive bending of the first side pole ear, and further avoiding the situation where the first side pole ear is pulled or torn when the multi-layer pole ears need to be bent to set the first side face of the adapter toward the battery cell, thereby ensuring the conductive reliability of the pole ear. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 It is a schematic diagram of the structure of a battery cell and a switching component in the related art;

[0041] Figure 2 It is a schematic diagram of the structure of a battery cell in the related art;

[0042] Figure 3 This is a first structural schematic diagram of the energy storage system disclosed in the embodiment of the present application;

[0043] Figure 4 It is a second structural schematic diagram of the energy storage system disclosed in the embodiment of the present application;

[0044] Figure 5 is a schematic diagram of the structure of the energy storage device disclosed in the embodiment of the present application;

[0045] Figure 6 is a schematic diagram of the exploded structure of the energy storage device disclosed in the embodiment of the present application;

[0046] Figure 7 The energy storage device disclosed in the embodiment of the present application is Figure 5 Cross-sectional view in the NN direction;

[0047] Figure 8 It is a schematic diagram of the structure of two battery cells disclosed in the embodiment of the present application;

[0048] Figure 9It is a schematic structural diagram of two battery cells and two adapter components disclosed in an embodiment of the present application;

[0049] Figure 10 It is a schematic structural diagram of two battery cells and two adapter components from another perspective disclosed in an embodiment of the present application;

[0050] Figure 11 It is a schematic structural diagram of a battery cell and an adapter component disclosed in an embodiment of the present application;

[0051] Figure 12 is Figure 7 a partial enlarged view of the M position in

[0052] Figure 13 It is a schematic diagram of theoretical calculation for confirming the connection position of the first side lug and the adapter component disclosed in an embodiment of the present application;

[0053] Figure 14 It is a first schematic structural diagram of a battery cell disclosed in an embodiment of the present application;

[0054] Figure 15 It is a second schematic structural diagram of a battery cell disclosed in an embodiment of the present application;

[0055] Figure 16 It is a third schematic structural diagram of a battery cell disclosed in an embodiment of the present application;

[0056] Figure 17 It is a fourth schematic structural diagram of a battery cell disclosed in an embodiment of the present application.

[0057] Main reference numeral description

[0058] 1000 - Energy storage system;

[0059] 100 - Energy storage device; 11 - Housing; 111 - Inner cavity; 112 - Opening; 12 - End cover assembly; 12a - Terminal hole; 121a - First terminal hole; 121b - Second terminal hole; 13 - Terminal; 131 - Positive terminal; 132 - Negative terminal; 14 - Battery cell; 14a - First battery cell; 14a1 - First battery cell body; 14a2 - First positive lug; 14a3 - First negative lug; 14b - Second battery cell; 14b1 - Second battery cell body; 14b2 - Second positive lug; 14b3 - Second negative lug; 141 - Battery cell body; 142 - Lug; 142a - Root; 1421 - Middle lug; 1422 - First side lug; 1422a - Connection position; 1423 - Second side lug; 15 - Adapter component; 15a - First adapter part; 15b - Second adapter part; 151 - First side; 152 - Second side;

[0060] 200 - Power conversion device; 300 - First user load; 400 - Second user load;

[0061] 210 - High - voltage cable; 310 - First power conversion device; 410 - Second power conversion device;

[0062] f1 - Length direction; f2 - Thickness direction; f3 - Height direction. Detailed implementation manners

[0063] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the following will clearly and completely describe the exemplary embodiments of the present application in conjunction with the accompanying drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only a part of the embodiments of the present application, rather than all the embodiments. That is to say, the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0064] It should be noted that the brief description of the terms in the present application is only for the convenience of understanding the following described embodiments, rather than intending to limit the embodiments of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0065] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present application.

[0066] The terms "first", "second", etc. used in the present application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of the present application, the first side tab can be called the second side tab, and similarly, the second side tab can be called the first side tab. Both the first side tab and the second side tab are side tabs, but they are not the same side tab.

[0067] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0068] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected" and "coupled" should be construed broadly. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0069] In the description of the present application, it should be noted that the singular forms of "a", "an" and "the" may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms "comprise / include" or "have" etc. specify the presence of the stated features, wholes, steps, operations, components, parts or combinations thereof, but do not preclude the possibility of the existence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0070] In addition, the term "and / or" used in this specification includes any and all combinations of the related listed items. For example, A and / or B may represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. That is to say, the term "and / or" used in this specification includes any and all combinations of the related listed items.

[0071] Since the energy required by people has strong temporality and spatiality, in order to rationally utilize energy and improve the energy utilization rate, it is necessary to store one form of energy in the same or converted into another form of energy through a medium or device and release it in a specific energy form based on future application needs. As is well known, the current main way to generate green electric energy is to develop green energy such as photovoltaic and wind power to replace fossil energy.

[0072] Currently, the generation of green electricity generally relies on photovoltaics, wind power, water potential, etc. However, wind energy and solar energy generally have problems such as strong intermittency and large volatility, which can cause grid instability, insufficient electricity during peak demand, and too much electricity during low demand. Unstable voltage can also damage the power. Therefore, due to insufficient electricity demand or insufficient grid acceptance capacity, the problem of "abandoning wind and light" may occur. To solve these problems, energy storage is required, that is, converting electrical energy into other forms of energy through physical or chemical means and storing it, and then converting the energy into electrical energy and releasing it when needed. Simply put, energy storage is similar to a large "portable charger", which stores electrical energy when photovoltaics and wind energy are sufficient and releases the stored electricity when needed.

[0073] Taking electrochemical energy storage as an example, the embodiment of the present application provides an energy storage device. There is a group of energy storage batteries in this energy storage device, which mainly uses the chemical elements in the battery as the energy storage medium. The charge and discharge process is accompanied by chemical reactions or changes of the energy storage medium. Simply put, it stores the electrical energy generated by wind energy and solar energy in chemical batteries, and then releases the stored electricity when the external electricity usage reaches the peak, or transfers it to places with a shortage of electricity for further use.

[0074] Currently, the application scenarios of energy storage (i.e., energy storage) are relatively extensive, including power generation side energy storage, grid side energy storage, renewable energy grid connection energy storage, and user side energy storage, etc. The types of corresponding energy storage devices include:

[0075] ① The large energy storage container applied in the grid side energy storage scenario can be used as a high-quality active and reactive power regulation power source in the grid, realizing the load matching of electrical energy in time and space, enhancing the consumption capacity of renewable energy, and being of great significance in grid system standby, alleviating the power supply pressure during peak loads, and peak shaving and frequency modulation.

[0076] ② The small and medium-sized energy storage cabinets applied in the industrial and commercial energy storage scenarios (such as banks, shopping malls, etc.) on the user side and the household small energy storage boxes applied in the household energy storage scenarios on the user side mainly operate in the mode of "peak shaving and valley filling". Since there is a large price difference in electricity bills at peak and valley positions according to electricity consumption demand, after users have energy storage devices, in order to reduce costs, they usually charge the energy storage cabinet / box during the low electricity price period; during the peak electricity price period, they release the electricity in the energy storage device for use to achieve the purpose of saving electricity bills. In addition, in remote areas and areas with high incidences of natural disasters such as earthquakes and hurricanes, the existence of household energy storage devices is equivalent to users providing backup power for themselves and the grid, eliminating the inconvenience caused by frequent power outages due to disasters or other reasons.

[0077] During the production process of energy storage devices, the assembly process has a crucial impact on the quality, cost, and performance of battery cell products. As an important connection structure connecting the tab and the terminal on the end cap, the main function of the tab is to collect and transmit electrons. Among them, the design of the height of the tab protruding relative to the battery cell has a significant impact on the cost and internal resistance of the battery cell. Under the condition of ensuring the assembly process, reducing the height of the tab as much as possible is beneficial to reducing the cost of the battery cell foil and the internal resistance of the tab, and thus beneficial to improving the performance of the battery cell.

[0078] In the related art, in order to ensure the battery performance of energy storage devices, a transfer piece is usually used to achieve the electrical connection between the tab of the battery cell and the terminal on the end cap. And during the processing of the battery cell in the related art, the transfer piece is usually arranged on one side of the multiple layers of tabs of the battery cell. After pressing the multiple layers of tabs onto the transfer piece, the multiple layers of tabs are welded to the transfer piece, thereby completing the assembly of the transfer piece and the multiple layers of tabs. Specifically, as Figure 1 shown, the multiple layers of tabs 142 are concentrated on one side of the battery cell body 141, and the multiple layers of tabs 142 can be connected to the transfer piece 15 by welding (such as ultrasonic welding).

[0079] Since the heights of each layer of tabs are the same after die-cutting, when pressing down the multiple layers of tabs during welding, the multiple layers of tabs will show a phenomenon of gradient increase from the upper layer to the lower layer, as Figure 2 shown. In order to ensure that the weld mark can completely fall on each tab, in the direction where the tab protrudes relative to the battery cell body, a certain distance h is reserved between the edge of the weld mark and the edge of the uppermost tab, that is, the uppermost tab after bending needs to reserve enough welding area for welding to ensure the welding quality of the tab. As a result, the required height of the tab is relatively high, which is not conducive to reducing the cost of the battery cell foil and the internal resistance of the tab.

[0080] In order to overcome the above problems, the applicant has found through research that by pressing the two side tabs in the multiple layers of tabs towards the middle tab respectively, and welding one of the tabs on one side of the multiple layers of tabs to the transfer piece, the bending degree of the tab farthest from the transfer piece can be reduced, so that while the tab farthest from the transfer piece has enough welding area after bending, the height of each layer of tabs can be reduced, especially the height of the tab farthest from the transfer piece, thereby reducing the cost of the battery cell foil and the internal resistance of the tab, and thus improving the performance of the battery cell.

[0081] At the same time, the applicant has also found through research that after the tab and the transfer piece are welded, the tab needs to be bent to bend the transfer piece to the top of the battery cell body for facilitating the welding of the transfer piece and the terminal on the end cap. Since in this process, the tab close to the transfer piece needs to be bent in the opposite direction, the two bending directions of the tab close to the transfer piece are opposite, which is likely to strain and tear the tab.

[0082] In view of this, an embodiment of the present application provides an energy storage device that can reduce the cost of the battery cell foil and the internal resistance of the tab while avoiding pulling and tearing the tab.

[0083] Next, the technical solutions in some embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in some embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0084] Please refer to Figure 3 , Figure 3 FIG. 10 is a schematic structural diagram of an energy storage system provided by an embodiment of the present application as a household energy storage system, and the embodiment of the present application Figure 3 is described by taking the household energy storage scenario in user-side energy storage as an example. The energy storage device provided by the embodiment of the present application is not limited to the household energy storage scenario.

[0085] As Figure 3 shown, the energy storage system 1000 provided by the embodiment of the present application includes an energy storage device 100, an electric energy conversion device 200 (photovoltaic panel), a first user load 300 (street lamp), and a second user load 400 (such as household appliances such as air conditioners, etc.). The energy storage device 100 is a small energy storage box and can be installed on an outdoor wall in a wall-mounted manner. Specifically, the photovoltaic panel can convert solar energy into electric energy during the low electricity price period. The energy storage device 100 is used to store the electric energy and supply it to the street lamp and household appliances for use during the high electricity price period, or supply power when the power grid is powered off / out of power.

[0086] Please refer to Figure 4 , Figure 4 FIG. 24 is a schematic structural diagram of an energy storage system provided by another embodiment of the present application, and the embodiment of the present application Figure 4 is described by taking the shared energy storage scenario on the power generation / distribution side as an example. The energy storage device 100 of the present application is not limited to its energy storage scenario on the power generation / distribution side.

[0087] As Figure 4As shown in the figure, the energy storage system 1000 provided by the embodiment of the present application may include an energy storage device 100, a high-voltage cable 210, a first power conversion device 310, and a second power conversion device 410. In the case of power generation, the first power conversion device 310 and the second power conversion device 410 are used to convert other forms of energy into electrical energy, connect to the high-voltage cable 210 and supply it for use on the power consumption side of the distribution network. When the power consumption load is low and the first power conversion device 310 and the second power conversion device 410 generate an excess of electricity, the excess electricity generated is stored in the energy storage device 100, reducing the curtailment rate of wind and light, and improving the problem of new energy power generation accommodation; when the power consumption load is high, the power grid issues an instruction, and the electricity stored in the energy storage device 100 is transmitted in parallel with the high-voltage cable 210 to supply power for use on the power consumption side, providing various services such as peak shaving, frequency modulation, and standby for the operation of the power grid, giving full play to the role of the power grid in peak shaving, promoting the peak shaving and valley filling of the power grid, and alleviating the power supply pressure of the power grid.

[0088] Optionally, the first power conversion device 310 and the second power conversion device 410 can convert at least one of solar energy, light energy, wind energy, thermal energy, tidal energy, biomass energy, and mechanical energy into electrical energy. In the present application, the number of energy storage devices 100 can be multiple, and the multiple energy storage devices 100 are connected in series or in parallel, and the multiple energy storage devices 100 are supported and electrically connected by a separator (not shown). In this embodiment, "multiple" means two or more. An energy storage box can also be provided outside the energy storage device 100 for housing the energy storage device 100.

[0089] Optionally, the energy storage device 100 may include, but is not limited to, battery cells, battery modules, battery packs, battery systems, etc. The actual application form of the energy storage device 100 provided by the embodiment of the present application may be, but is not limited to, the listed products, and may also be other application forms. The embodiment of the present application does not strictly limit the application form of the energy storage device 100.

[0090] The embodiment of the present application will only be described by taking the energy storage device 100 as a battery cell as an example.

[0091] Optionally, the energy storage device 100 may be a polygonal battery, a cylindrical battery, etc., and can be specifically selected according to the actual situation, and is not specifically limited in this embodiment. It can be seen that the energy storage device 100 in the present application is not limited to a battery of a specific shape, and the shape of the energy storage device 100 is diverse and flexible.

[0092] Among them, the polygonal battery includes a square battery, a pentagonal battery, a hexagonal battery, and so on.

[0093] In order to more conveniently describe the energy storage device 100 provided by the embodiment of the present application, as an example rather than a limitation, the following will take the energy storage device 100 as a square battery as an example to elaborate the technical solution of the present application in detail.

[0094] Please refer to Figures 5 to 8 , Figure 5 which shows that the energy storage device in the present application is a square battery, Figure 6 and is a schematic exploded view of the energy storage device in a specific embodiment, Figure 7 and is a cross-sectional view of the energy storage device in a specific embodiment along the Figure 5 N-N direction in Figure 8 and is a schematic structural view of two battery cells arranged along their thickness directions.

[0095] As Figures 5 to 8 shown, the energy storage device 100 provided in the embodiment of the present application includes a housing 11, an end cap assembly 12, a terminal 13, a battery cell 14, and an adapter 15. Among them, the housing 11 has an inner cavity 111 and an opening 112 communicating with the inner cavity 111. The end cap assembly 12 is sealingly disposed at the opening 112, and the end cap assembly 12 is provided with a through terminal hole 12a. The terminal 13 is disposed through the terminal hole 12a. The battery cell 14 is disposed in the inner cavity 111, and the battery cell 14 has a length direction f1, a thickness direction f2, and a height direction f3.

[0096] In the present application, the battery cell 14 includes a battery cell body 141 and multiple layers of tabs 142 disposed on the battery cell body 141. The multiple layers of tabs 142 are spaced along the thickness direction f2 of the battery cell 14. The adapter 15 is electrically connected to the terminal 13 and the multiple layers of tabs 142 respectively, so as to realize the electrical connection between the battery cell 14 and the terminal 13, facilitate leading out the current stored in the battery cell 14 through the terminal 13, or facilitate introducing external current through the terminal 13 into the battery cell 14 and storing it in the battery cell 14.

[0097] Optionally, the housing 11 is a metal shell, such as an aluminum shell. Of course, the housing 11 can also be made of other materials. The end cap assembly 12 may at least include an end cover plate. In other embodiments, the end cap assembly 12 may further include a lower plastic and / or an upper plastic.

[0098] Optionally, the battery cell 14 may be formed by stacking multiple positive electrode plates, multiple separators, and multiple negative electrode plates, or may be formed by winding a positive electrode plate, a separator, and a negative electrode plate through a winding process. Specifically, it can be selected according to actual conditions and is not specifically limited in this embodiment.

[0099] In some embodiments, the number of battery cells 14 may be multiple, such as two, three, four, five, six, or more, etc. The multiple battery cells 14 may be connected in parallel or in series.

[0100] It should be noted that Figure 6The purpose is only to schematically describe the connection relationship between the housing 11 and the end cap assembly 12, and does not specifically limit the connection positions, specific structures, and quantities of each component. The structure schematically shown in the embodiments of the present application does not constitute a specific limitation on the energy storage device 100. In other embodiments of the present application, the energy storage device 100 includes more or fewer components than Figure 6 shown, or combines certain components, or splits certain components, or has different component arrangements. Figure 6 The components shown can be implemented in hardware, software, or a combination of software and hardware.

[0101] As Figure 6 、 Figure 7 and Figure 8 shown, the pole holes 12a on the end cap assembly 12 may include a first pole hole 121a and a second pole hole 121b; the pole 13 may include a positive pole 131 and a negative pole 132. Among them, the positive pole 131 passes through the first pole hole 121a, and the negative pole 132 passes through the second pole hole 121b; the battery cell 14 may include a first battery cell 14a and a second battery cell 14b. The first battery cell 14a includes a first battery cell body 14a1, a first positive ear 14a2 and a first negative ear 14a3 provided on the first battery cell body 14a1. The second battery cell 14b includes a second battery cell body 14b1, a second positive ear 14b2 and a second negative ear 14b3 provided on the second battery cell body 14b1. Both the first battery cell body 14a1 and the second battery cell body 14b1 include the aforementioned battery cell body 141. The first positive ear 14a2, the first negative ear 14a3, the second positive ear 14b2, and the second negative ear 14b3 all include the aforementioned multi-layered ears 142. The adapter 15 may include a first adapter component 15a and a second adapter component 15b. The first adapter component 15a is electrically connected to the positive pole 131, the first positive ear 14a2, and the second positive ear 14b2 respectively. The second adapter component 15b is electrically connected to the negative pole 132, the first negative ear 14a3, and the second negative ear 14b3 respectively. Thus, current can be led out or led into through the positive pole 131 and the negative pole 132.

[0102] Among them, as Figure 8 shown, the first battery cell 14a and the second battery cell 14b are arranged along the thickness direction f2 of the battery cell 14. Along the thickness direction f2 of the battery cell 14, the first positive ear 14a2 and the second positive ear 14b2 are oppositely arranged, and the first negative ear 14a3 and the second negative ear 14b3 are oppositely arranged. And / or, along the thickness direction f2 of the battery cell 14, the first positive ear 14a2 and the first negative ear 14a3 are located on the side of the first battery cell body 14a1 facing the second battery cell body 14b1, and the second positive ear 14b2 and the second negative ear 14b3 are located on the side of the second battery cell body 14b1 facing the first battery cell body 14a1.

[0103] It can be understood that during the assembly of the battery cell 14, as Figure 9 shown, the first battery cell 14a and the second battery cell 14b are arranged along the height direction f3 of the battery cell 14, and as Figure 10 shown, in the height direction f3 of the battery cell 14, the first negative electrode tab 14a3 of the first battery cell 14a and the second negative electrode tab 14b3 of the second battery cell 14b can be arranged opposite to each other, and the first positive electrode tab 14a2 of the first battery cell 14a and the second positive electrode tab 14b2 of the second battery cell 14b can be arranged opposite to each other. Thus, it is convenient for the first transfer component 15a to be welded to the first positive electrode tab 14a2 and the second positive electrode tab 14b2, and it is convenient for the second transfer component 15b to be welded to the first negative electrode tab 14a3 and the second negative electrode tab 14b3, which is beneficial to realizing the welding of the first transfer component 15 to the first positive electrode tab 14a2 and the second positive electrode tab 14b2, and quickly realizing the welding of the second transfer component 15b to the first negative electrode tab 14a3 and the second negative electrode tab 14b3, saving welding time.

[0104] In addition, as Figure 8 shown, since both the first positive electrode tab 14a2 of the first battery cell 14a and the second positive electrode tab 14b2 of the second battery cell 14b are located outside the battery cell 14, and both the first negative electrode tab 14a3 of the first battery cell 14a and the second negative electrode tab 14b3 of the second battery cell 14b are also located outside the battery cell 14, when the first battery cell 14a and the second battery cell 14b are arranged along the thickness direction f2 of the battery cell 14, the positions of the first positive electrode tab 14a2 and the second positive electrode tab 14b2 are far apart, and the positions of the first negative electrode tab 14a3 and the second negative electrode tab 14b3 are also far apart. It can avoid the first positive electrode tab 14a2 and the second positive electrode tab 14b2 from overlapping to cause a short circuit, and the first negative electrode tab 14a3 and the second negative electrode tab 14b3 from overlapping to cause a short circuit. In this case, both the first positive electrode tab 14a2 and the second positive electrode tab 14b2 can have a large connection area with the first transfer component 15a, and both the first negative electrode tab 14a3 and the second negative electrode tab 14b3 can have a large connection area with the second transfer component 15b, which is beneficial to improving the connection strength between the battery cell 14 and the transfer component 15, and avoiding the problem of conductive failure caused by too low connection strength between the battery cell 14 and the transfer component 15.

[0105] Please refer to Figure 11 and Figure 12, the multi-layer tabs 142 may include a middle tab 1421, a first side tab 1422, and a second side tab 1423. The first side tab 1422 and the second side tab 1423 are respectively located on both sides of the middle tab 1421 in the thickness direction f2 of the battery cell 14, and the first side tab 1422 and the second side tab 1423 are respectively bent toward the middle tab 1421. The adapter 15 has opposite first side 151 and second side 152. The first side 151 is electrically connected to the first side tab 1422, and the second side 152 is electrically connected to the terminal 13.

[0106] In the above solution, the first side tab 1422 and the second side tab 1423 on both sides of the middle tab 1421 are respectively bent and pressed toward the middle tab 1421, and then the first side 151 of the adapter 15 is attached and electrically connected to the first side tab 1422. Compared with the method of only bending and pressing the second side tab 1423 toward the first side tab 1422, it can reduce the bending degree of the second side tab 1423, so that while the second side tab 1423 has a sufficient welding area after bending, for example, when ensuring that the distance h from the edge of the weld mark to the edge of the second side tab 1423 in the direction in which the tab 142 protrudes relative to the battery cell body 141 remains unchanged, the height of each layer of tabs 142, especially the height of the second side tab 1423, can be reduced, thereby reducing the cost of the battery cell foil material and the internal resistance of the tab 142, and improving the performance of the battery cell.

[0107] Optionally, the number of the middle tab 1421, the first side tab 1422, and the second side tab 1423 may be the same or different, and the number of the middle tab 1421 may be one or multiple, the number of the first side tab 1422 may be one or multiple, and the number of the second side tab 1423 may be one or multiple.

[0108] In the present application, the multi-layer tab 142 can be bent from the first state to the second state. Among them, the first state is configured such that the first side 151 is connected (such as welded) to the first side tab 1422, and the multi-layer tab 142 is not bent and the first side 151 is arranged toward the battery cell body 141 (as Figure 11 shown), and the second state is configured such that the multi-layer tab 142 is bent and the first side 151 is arranged toward the battery cell body 141 (as Figure 12 shown).

[0109] In the present application, each tab 142 has a root 142a connected to the battery cell body 141, and the first side tab 1422 has a connection position 1422a connected to the adapter 15, such as the solder joint where the first side tab 1422 is welded to the adapter 15.

[0110] In order to facilitate determination of the distance L between the connection position 1422a of the first side tab 1422 and the root 142a of the first side tab 1422 in the thickness direction f2 of the battery cell 14 after the first side tab 1422 is bent toward the middle tab 1421, 0 ,like Figures 11 to 13 As shown, the embodiment of the present application exemplarily takes the root 142a of the second side pole ear 1423 as the origin, the thickness direction f2 of the battery cell 14 as the x-axis, and the extension direction of the pole ear 142 as the y-axis to establish a rectangular coordinate system, then the coordinates of the root 142a of any pole ear 142 are (x, 0), the coordinates of the root 142a of the first side pole ear 1422 are (A1, 0), x is between 0 and A1, that is, 0≤x≤A1, in other words, x does not exceed half of the thickness of the battery cell body 141; when the multi-layer pole ear 142 is not bent and the first side surface 151 is set toward the battery cell 14, that is, when the multi-layer pole ear 142 is in the first state, the coordinates of the connection position 1422a are (a, b), and when the multi-layer pole ear 142 is bent and the first side surface 151 is set toward the battery cell 14, that is, when the multi-layer pole ear 142 is in the second state, the coordinates of the connection position 1422a are (c, d). Among them, L 0 =A1-a.

[0111] When the multi-layer tab 142 is not bent and the first side surface 151 is disposed toward the battery cell 14, the distance L between the connection position 1422a and the root 142a of any tab 142 is 1 =((ax) 2 +b 2 ) 1 / 2 When the multi-layer tab 142 is bent and the first side is disposed toward the battery cell 14, the distance L between the connection position 1422a and the root 142a of any tab 142 is 2 ={(cx) 2 +d 2} 1 / 2 , when L 1 >L 2 This can prevent the first side pole ear 1422 from being excessively pulled when the multi-layer pole ear 142 is bent to set the first side surface 151 toward the battery cell 14, thereby preventing the first side pole ear 1422 from being excessively bent, and further preventing the first side pole ear 1422 from being pulled or torn when the multi-layer pole ear 142 needs to be bent to set the first side surface 151 of the adapter 15 toward the battery cell 14, thereby ensuring the conductive reliability of the pole ear 142.

[0112] That is, the energy storage device 100 satisfies the following relationship: L 1 2 -L 2 2 =((ax) 2+b 2 )-{(cx) 2 +d 2}>0, where b, c, d, and x can all be obtained based on actual cell testing. By calculating the above relationship, the range of a can be calculated, and thus L can be determined. 0 The range can be used to determine the distance range between the connection position 1422a of the first side pole ear 1422 and its root 142a in the thickness direction f2 of the battery cell 14 after the first side pole ear 1422 is bent toward the middle pole ear 1421, so as to determine the bending degree of the first side pole ear 1422 toward the middle pole ear 1421, thereby avoiding excessive bending of the first side pole ear 1422, and further avoiding the situation where the first side pole ear 1422 is stretched or torn when the multi-layer pole ear 142 needs to be bent to set the first side surface of the adapter 15 toward the battery cell, so as to ensure the conductive reliability of the pole ear 142.

[0113] Since the battery cell 14 will inevitably expand during the charge and discharge process, wherein the expansion rate of the battery cell 14 in the thickness direction f2 is k, when the multilayer tab 142 is bent to set the first side toward the battery cell 14, and the battery cell 14 expands, the coordinates of the root 142a of any tab 142 are ((1+k)x, 0), and the distance L between the connection position 1422a and the root 142a of any tab 142 is 3 ={(c-(1+k)x) 2 +d 2} 1 / 2 , when L 1 >L 3 When the energy storage device 100 satisfies the following relationship: 1 2 -L 3 2 =((ax) 2 +b 2 )-{(c-(1+k)x) 2 +d 2 When}>0, excessive pulling of the first side tab 1422 can be avoided when the battery cell 14 expands, thereby avoiding the first side tab 1422 from being pulled or torn when the battery cell 14 expands, thereby ensuring the conductive reliability of the tab 142.

[0114] As a first optional implementation, Figure 14As shown, when neither the first side tab 1422 nor the second side tab 1423 is bent towards the middle tab 1421 and the first side tab 1422 is not connected to the first side, the height of each tab 142 protruding relative to the battery cell 14 is equal. Thus, the height of each tab 142 protruding relative to the battery cell 14 can be kept the same, without the need for special die-cutting of the tabs 142, which is conducive to simplifying the die-cutting process of the tabs 142.

[0115] As a second alternative embodiment, as Figure 15 shown, when neither the first side tab 1422 nor the second side tab 1423 is bent towards the middle tab 1421 and the first side tab 1422 is not connected to the first side, the height of the first side tab 1422 protruding relative to the battery cell body 141 is greater than the height of the middle tab 1421 protruding relative to the battery cell body 141. After the first side tab 1422 and the second side tab 1423 are respectively bent and pressed towards the middle tab 1421, that is, after the multi-layer tabs are pressed and connected, the ends of the middle tab 1421 and the first side tab 1422 away from the battery cell body 141 can be made flush. Compared with the method where the height of each tab 142 is equal, the height of the middle tab 1421 can be reduced, which is conducive to reducing the cost of the battery cell foil material and the internal resistance of the tabs, so that the performance of the battery cell can be improved.

[0116] As a third alternative embodiment, as Figure 16 shown, when neither the first side tab 1422 nor the second side tab 1423 is bent towards the middle tab 1421 and the first side tab 1422 is not connected to the first side, the height of the second side tab 1423 protruding relative to the battery cell body 141 is greater than the height of the middle tab 1421 protruding relative to the battery cell body 141. After the first side tab 1422 and the second side tab 1423 are respectively bent and pressed towards the middle tab 1421, that is, after the multi-layer tabs are pressed and connected, the ends of the middle tab 1421 and the second side tab 1423 away from the battery cell 14 can be made flush. Compared with the method where the height of each tab 142 is equal, the height of the middle tab 1421 can be reduced, which is conducive to reducing the cost of the battery cell foil material and the internal resistance of the tabs 142, so that the performance of the battery cell can be improved.

[0117] As a fourth alternative embodiment, as Figure 17As shown, when neither the first side tab 1422 nor the second side tab 1423 is bent towards the middle tab 1421 and the first side tab 1422 is not connected to the first side, the height by which the first side tab 1422 protrudes relative to the battery cell body 141 is greater than the height by which the middle tab 1421 protrudes relative to the battery cell body 141, and the height by which the second side tab 1423 protrudes relative to the battery cell body 141 is greater than the height by which the middle tab 1421 protrudes relative to the battery cell body 141. After the first side tab 1422 and the second side tab 1423 are respectively bent and pressed towards the middle tab 1421, that is, after the multi-layer tabs are pressed and connected, the ends of the middle tab 1421, the first side tab 1422, and the second side tab 1423 that are away from the battery cell body 141 can be made flush. Compared with the method in which the height of each tab 142 is equal, the height of the middle tab 1421 can be reduced at least, which is beneficial to reducing the cost of the battery cell foil and the internal resistance of the tab 142, and improving the performance of the battery cell.

[0118] In some embodiments, when neither the first side tab 1422 nor the second side tab 1423 is bent towards the middle tab 1421 and the first side tab 1422 is not connected to the first side, the height by which the tab 142 protrudes relative to the battery cell body 141 first decreases and then increases along the thickness direction f2 of the battery cell 14. That is, in the direction from the middle tab 1421 to the first side tab 1422, the height by which the tab 142 protrudes relative to the battery cell body 141 gradually increases, and in the direction from the middle tab 1421 to the second side tab 1423, the height by which the tab 142 protrudes relative to the battery cell body 141 gradually increases. In this way, after the first side tab 1422 and the second side tab 1423 are respectively bent and pressed towards the middle tab 1421, that is, after the multi-layer tabs are pressed and connected, the ends of the respective layers of tabs 142 that are away from the battery cell 14 can be made flush. This can not only improve the aesthetic degree and the fixing firmness of the tabs, but also, compared with the method in which the height of each tab 142 is equal, reduce the height of the tab 142, which is beneficial to reducing the cost of the battery cell foil and the internal resistance of the tab 142, and improving the performance of the battery cell.

[0119] In some embodiments, when neither the first side tab 1422 nor the second side tab 1423 is bent towards the middle tab 1421 and the first side tab 1422 is not connected to the first side, the distance between any two adjacent layers of tabs 142 is equal, which can make the respective layers of tabs 142 arranged at equal intervals, thus being beneficial to ensuring the charge and discharge performance and the comprehensive performance of the battery cell 14.

[0120] In order to improve the neatness of the multi-layer tab 142 after lamination, in some embodiments, when the first side tab 1422 is not connected to the first side, the height difference of any two adjacent layers of tabs 142 protruding relative to the battery cell body 141 is equal, that is, the heights of the multi-layer tabs 142 protruding relative to the battery cell body 141 are arranged in an arithmetic progression. In this way, not only can the multi-layer tabs 142 be flatter after lamination, but also the heights of the multi-layer tabs 142 protruding relative to the battery cell body 141 are arranged in an arithmetic progression, which can form a regular change. Therefore, it is convenient for die-cutting and forming of each layer of tabs 142, and precise control of the height of each layer of tabs 142 can be achieved.

[0121] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0122] In addition, the above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the content of this specification should not be construed as a limitation on the present application, and the protection scope of the present application should be subject to the appended claims.

Claims

1. An energy storage device, characterized in that: The energy storage device comprises: A housing having an inner cavity and an opening communicating with the inner cavity; An end cover assembly, the end cover assembly is sealed and arranged at the opening, and the end cover assembly is provided with a through pole hole; A pole, wherein the pole is inserted into the pole hole; A battery cell, wherein the battery cell is arranged in the inner cavity, the battery cell comprises a battery cell body and a multi-layered pole ear arranged on the battery cell body, the multi-layered pole ear is arranged at intervals along the thickness direction of the battery cell, and the multi-layered pole ear comprises a middle pole ear, a first side pole ear and a second side pole ear, the first side pole ear and the second side pole ear are respectively located on both sides of the middle pole ear in the thickness direction of the battery cell, and the first side pole ear and the second side pole ear are respectively bent toward the middle pole ear; and, A transition piece, the transition piece having a first side surface and a second side surface opposite to each other, the first side surface is electrically connected to the first side tab, and the second side surface is electrically connected to the pole; The multi-layer tab can be bent from a first state to a second state, wherein the first state is configured as a state in which the multi-layer tab is not bent and the first side is disposed toward the battery cell body, and the second state is configured as a state in which the multi-layer tab is bent and the first side is disposed toward the battery cell body; Each of the tabs has a root connected to the battery body, the first side tab has a connection position connected to the adapter, and a rectangular coordinate system is established with the root of the second side tab as the origin, the thickness direction of the battery cell as the x-axis, and the extension direction of the tab as the y-axis. The coordinates of the root of any tab are (x, 0), and when the multi-layer tab is in the first state, the coordinates of the connection position are (a, b), and when the multi-layer tab is in the second state, the coordinates of the connection position are (c, d); wherein, ((a-x) 2 +b 2 )-{(c-x) 2 +d 2 }>0。 2. The energy storage device according to claim 1, characterized in that: The expansion rate of the battery cell in the thickness direction is k, wherein the energy storage device satisfies the following relationship: ((a-x) 2 +b 2 )-{(c-(1+k)x) 2 +d 2 }>0。 3. The energy storage device according to claim 1, characterized in that: When the first side pole lug and the second side pole lug are not bent toward the middle pole lug, and the first side pole lug is not connected to the first side surface, the protrusion height of each pole lug relative to the battery cell body is equal.

4. The energy storage device according to claim 1, characterized in that: When the first side pole ear and the second side pole ear are not bent toward the middle pole ear, and the first side pole ear is not connected to the first side surface; The height of the first side tab protruding relative to the battery cell body is greater than the height of the middle tab protruding relative to the battery cell body, and / or the height of the second side tab protruding relative to the battery cell body is greater than the height of the middle tab protruding relative to the battery cell body.

5. The energy storage device according to claim 4, characterized in that: When the first side tab and the second side tab are not bent toward the middle tab and the first side tab is not connected to the first side surface, the height of the tab protruding relative to the battery cell body first decreases and then increases along the thickness direction of the battery cell.

6. The energy storage device according to claim 5, characterized in that: When the first side pole lug and the second side pole lug are not bent toward the middle pole lug, and the first side pole lug is not connected to the first side surface, the spacing between any two adjacent layers of the pole lugs is equal.

7. The energy storage device according to claim 5, characterized in that: When the first side tab and the second side tab are not bent toward the middle tab, and the first side tab is not connected to the first side surface, the height differences of any two adjacent layers of the tabs protruding relative to the battery cell body are equal.

8. The energy storage device according to any one of claims 1 to 7, characterized in that: The energy storage device is a polygonal battery or a cylindrical battery.

9. The energy storage device according to any one of claims 1 to 7, characterized in that: The pole hole comprises a first pole hole and a second pole hole; The poles include a positive pole and a negative pole, the positive pole is inserted into the first pole hole, and the negative pole is inserted into the second pole hole; The battery cell comprises a first battery cell and a second battery cell, the first battery cell comprises a first battery cell body, a first positive electrode ear and a first negative electrode ear arranged on the first battery cell body, the second battery cell comprises a second battery cell body, a second positive electrode ear and a second negative electrode ear arranged on the second battery cell body, the first battery cell body and the second battery cell body both comprise the battery cell body, and the first positive electrode ear, the first negative electrode ear, the second positive electrode ear and the second negative electrode ear all comprise the multi-layer electrode ear; Wherein, the first battery cell and the second battery cell are arranged along the thickness direction of the battery cell, and along the thickness direction of the battery cell, the first positive electrode ear is arranged opposite to the second positive electrode ear, and the first negative electrode ear is arranged opposite to the second negative electrode ear, and / or, along the thickness direction of the battery cell, the first positive electrode ear and the first negative electrode ear are located on the side of the first battery cell body facing away from the second battery cell body, and the second positive electrode ear and the second negative electrode ear are located on the side of the second battery cell body facing away from the first battery cell body; The adapter includes a first adapter component and a second adapter component, the first adapter component is electrically connected to the positive electrode column, the first positive electrode ear and the second positive electrode ear respectively, and the second adapter component is electrically connected to the negative electrode column, the first negative electrode ear and the second negative electrode ear respectively.

10. An energy storage system, characterized in that: The energy storage system comprises an energy storage device as described in any one of claims 1-9.

Images