Battery cells and their preparation processes, energy storage equipment

Abstract

The present application relates to the field of energy storage technology, and in particular to a battery cell and its preparation process and energy storage equipment. The battery cell includes a top cover structure, which includes: a pole, including a main body, a first bend and a second bend. Along the height direction of the battery cell, the first and second bends are arranged on both sides of the main body and extend horizontally along the width direction; along the width direction, the first and second bends projected on the same straight line have opposite extension directions in the width direction; along the length direction, the bending directions of adjacent first bends in the width direction are opposite, and the bending directions of adjacent second bends in the width direction are opposite; the length of the pole accounts for ≥10% of the length of the battery cell; a bare aluminum sheet; a connecting sheet, provided with a first connecting hole with a staggered distribution, the second bend is engaged with the first connecting hole, and the second bend does not protrude from the surface of the connecting sheet. The battery cell of the present application improves the current carrying capacity of the pole while ensuring the connection stability between the pole and the connecting sheet.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a battery cell and a preparation process thereof, and an energy storage device. Background Art

[0002] The battery cell includes a top cover structure, which includes a pole and a connecting piece. The top cover structure is connected to the bare battery cell in the shell through the cooperation of the pole and the connecting piece. Among them, the pole is a key component that connects the internal electrode of the battery cell with the external circuit, and is responsible for electrical connection, current carrying, thermal management, mechanical fixation and other functions. As the capacity of the battery cell increases, large-capacity batteries need to carry a larger current during charging and discharging. In order to ensure that the current can pass through the pole stably, a larger pole is needed to reduce contact resistance and improve current carrying capacity.

[0003] However, when the battery cell uses large-sized poles, the large-sized poles and the connecting pieces are welded along the circumferential edge of the poles. The connection stability between the two is poor, which can easily affect the output voltage and efficiency of the battery cell. Summary of the invention

[0004] In view of this, the present application provides a battery cell and its preparation process, and an energy storage device. The battery cell adopts a pole with a large-size structure, and the pole is provided with a first bending portion and a second bending portion. The second bending portion is clamped with a connecting piece, thereby improving the current carrying capacity of the pole while ensuring the connection stability between the pole and the connecting piece.

[0005] In a first aspect, the present application provides a battery cell, including a top cover structure, wherein the top cover structure includes:

[0006] A pole, comprising a main body, a first bending portion and a second bending portion; wherein, along the height direction of the battery cell, the first bending portion and the second bending portion are respectively arranged on both sides of the main body, and extend horizontally along the width direction of the battery cell; along the width direction of the battery cell, the first bending portion and the second bending portion projected on the same straight line extend in opposite directions in the width direction of the battery cell; along the length direction of the battery cell, the adjacent first bending portions have opposite bending directions in the width direction of the battery cell, and the adjacent second bending portions have opposite bending directions in the width direction of the battery cell; the length of the pole accounts for ≥10% of the length of the battery cell;

[0007] The bare aluminum sheet is provided with a mounting hole, the main body of the pole is inserted into the mounting hole, and along the height direction of the battery core, the first bending portion and the second bending portion are respectively located on both sides of the mounting hole;

[0008] The connecting sheet is provided with first connecting holes which are staggered, the second bent portion of the pole is engaged with the first connecting hole, and the second bent portion does not protrude from the surface of the connecting sheet away from the bare aluminum sheet.

[0009] In some embodiments, along the length direction of the battery cell, the length of the pole is 10 mm to 100 mm.

[0010] In some embodiments, along the length direction of the battery core, the width of the first bent portion and the second bent portion is 1 mm to 10 mm.

[0011] In some embodiments, along the width direction of the battery core, the extension length of the first bent portion and the second bent portion is 0.5 mm to 5 mm.

[0012] In some embodiments, along the length direction of the battery core, the spacing distance between adjacent first bending portions is 0.17 mm to 3.4 mm, and the spacing distance between adjacent second bending portions is 0.17 mm to 3.4 mm.

[0013] In some embodiments, the connecting piece is welded to the second bent portion after being clamped.

[0014] In a second aspect, the present application provides a process for preparing a battery cell, including an assembly process of a top cover structure, wherein the assembly process of the top cover structure includes:

[0015] Prepare a pole, a bare aluminum sheet and a connecting sheet; wherein the pole comprises a main body, a first extending portion and a second extending portion, and along the height direction of the battery cell, the first extending portion and the second extending portion are respectively arranged at two ends of the main body; the bare aluminum sheet is provided with a mounting hole, and the connecting sheet is provided with a staggered first connecting hole;

[0016] The main body of the pole is inserted into the mounting hole of the bare aluminum sheet, and the first extension portion is bent to form a first bending portion, and the second extension portion is bent to form a second bending portion; wherein the first bending portion and the second bending portion have opposite bending directions in the width direction of the battery cell; and along the length direction of the battery cell, the adjacent first bending portions have opposite bending directions in the width direction of the battery cell, and the adjacent second bending portions have opposite bending directions in the width direction of the battery cell;

[0017] The first connection hole of the connection sheet is clamped with the second bent portion of the pole, and the second bent portion does not protrude from the surface of the connection sheet away from the bare aluminum sheet.

[0018] In some embodiments, the assembly process of the top cover structure further includes:

[0019] The second bent portion of the pole is welded to an edge of the first connecting hole of the connecting sheet.

[0020] In a third aspect, the present application provides an energy storage device, which includes a battery management system, an energy storage inverter, an energy management system and a battery pack, wherein the battery pack includes a plurality of battery cells as described in any one of the first aspects or prepared by the preparation process of the battery cells as described in any one of the second aspects.

[0021] In some embodiments, the battery pack further includes a tab, the battery cell is connected to an external circuit via the tab, the tab is provided with second connection holes that are staggered, the first bent portion of the pole of the battery cell is engaged with the second connection hole, and the first bent portion does not protrude from the surface of the tab away from the bare aluminum sheet.

[0022] The above technical solution has at least the following beneficial effects:

[0023] In the battery cell of the present application, the length of the pole accounts for ≥10% of the length of the battery cell, that is, the pole is of a larger size. The large-sized pole has higher mechanical strength, lower contact resistance and greater current carrying capacity; and the larger-sized pole has better heat dissipation performance, which can ensure that the battery cell operates within a safe temperature range; at the same time, the pole is provided with a second bending portion, and along the length direction of the battery cell, adjacent second bending portions have opposite bending directions in the width direction of the battery cell, and the connecting sheet is provided with staggered connecting holes. When the battery cell is assembled, the second bending portion of the pole can be snapped into the connecting hole to ensure the connection stability between the pole and the connecting sheet. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 An exploded view of the battery cell provided for this application;

[0025] Figure 2 An exploded view of a portion of the top cover structure of the battery cell provided in this application;

[0026] Figure 3 A schematic diagram of the structure of the insulating film of the battery cell provided in this application;

[0027] Figure 4 A schematic diagram of the structure of the connecting piece of the battery cell is provided for this application;

[0028] Figure 5 A schematic diagram of the structure of the light aluminum sheet of the battery cell provided for this application;

[0029] Figure 6 A schematic diagram of the structure of the insulating sheet of the battery cell provided for this application;

[0030] Figure 7A schematic diagram of the structure of the sealing ring of the battery cell is provided for this application;

[0031] Figure 8 A schematic structural diagram of a first pressing block of a battery cell is provided for this application;

[0032] Fig. 9 A schematic diagram of the structure of a second pressing block of a battery cell is provided for this application;

[0033] Fig.10 A schematic diagram of the structure of the second pressing block of the battery cell from another angle is provided for the present application;

[0034] Fig.11 A schematic diagram of the structure of the pole of the battery cell is provided for this application;

[0035] Fig.12 A schematic diagram of the structure of a battery cell is provided for this application.

[0036] Figure ID:

[0037] 1. Top cover structure; 11. Pole; 111. Main body; 112. First bending portion; 113. Second bending portion; 12. Light aluminum sheet; 121. Mounting hole; 13. Connecting sheet; 131. First connecting hole; 132. Welding position; 14. Connecting area; 141. First area; 142. Second area; 15. Sealing ring; 161. First pressing block; 162. Second pressing block; 17. Insulating sheet;

[0038] 2. Bare battery cell; 21. Bottom support sheet;

[0039] 3. Shell;

[0040] 4. Insulating film; 41. Film body; 42. Extended portion; 421. First extended portion; 422. Second extended portion; 43. First portion; 44. Second portion;

[0041] 5. Bar piece; 51. Second connecting hole. DETAILED DESCRIPTION

[0042] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0043] It should be clear that the described embodiments are only 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 ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0044] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0045] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0046] It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described at the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0047] In the battery cells of energy storage devices, the top cover structure is connected to the bare battery cells in the shell through the cooperation of the poles and the connecting sheets. Among them, the poles are the key components that connect the internal electrodes of the battery cells with the external circuits, and are responsible for electrical connection, current carrying, thermal management, mechanical fixation and other functions.

[0048] As the capacity of the battery cell increases, the large-capacity battery cell needs to carry a larger current during charging and discharging. In order to ensure that the current can stably pass through the pole, a larger pole is needed to reduce the contact resistance and improve the current carrying capacity. However, when the battery cell uses a large-sized pole, the large-sized pole and the connecting piece are welded along the circumferential edge of the pole. The connection stability between the two is poor, which can easily affect the output voltage and efficiency of the battery cell.

[0049] In view of this, the present application provides a battery cell, including a top cover structure 1, please refer to Figure 1 to Figure 12 , the top cover structure 1 comprises:

[0050] The pole 11 comprises a main body 111, a first bending portion 112 and a second bending portion 113; wherein, along the height direction of the battery cell, the first bending portion 112 and the second bending portion 113 are respectively arranged on both sides of the main body 111, and extend horizontally along the width direction of the battery cell; along the width direction of the battery cell, the first bending portion 112 and the second bending portion 113 projected on the same straight line extend in opposite directions in the width direction of the battery cell; along the length direction of the battery cell, the adjacent first bending portions 112 have opposite bending directions in the width direction of the battery cell, and the adjacent second bending portions 113 have opposite bending directions in the width direction of the battery cell; the length of the pole 11 accounts for ≥10% of the length of the battery cell;

[0051] The bare aluminum sheet 12 is provided with a mounting hole 121, the main body 111 of the pole 11 is inserted into the mounting hole 121, and along the height direction of the battery cell, the first bending portion 112 and the second bending portion 113 are respectively located on both sides of the mounting hole 121;

[0052] The connecting piece 13 is provided with staggered first connecting holes 131 , the second bending portion 113 of the pole 11 is engaged with the first connecting hole 131 , and the second bending portion 113 does not protrude from the surface of the connecting piece 13 away from the bare aluminum sheet 12 .

[0053] In the above scheme, in the battery cell of the present application, the length of the pole 11 accounts for ≥10% of the length of the battery cell, and further, the total length of the positive and negative poles accounts for ≥10% of the length of the battery cell, that is, the pole 11 is larger in size, and the larger pole 11 has higher mechanical strength, lower contact resistance and greater current carrying capacity; and the larger pole 11 has better heat dissipation performance, which can ensure that the battery cell operates within a safe temperature range; at the same time, the pole 11 is provided with a second bending portion 113, and along the length direction of the battery cell, adjacent second bending portions 113 have opposite bending directions in the width direction of the battery cell, and the connecting sheet 13 is provided with a staggered first connecting hole 131. When the battery cell is assembled, the second bending portion 113 of the pole 11 can be snapped into the first connecting hole 131 to ensure the connection stability between the pole 11 and the connecting sheet 13.

[0054] In some embodiments, the energy storage device is specifically assembled from a battery pack, a battery management system, an energy storage converter, and an energy management system, and the energy storage device can be used to store and release electrical energy. Among them, the battery pack is used to provide a stable power output; the battery management system (Battery Management System, BMS) is a key component used to monitor, control and protect the operating status of the battery pack, including the voltage, current, temperature and other parameters of each battery cell in the battery pack, and through balanced charging, control of the charging and discharging process, and protection of the battery pack from damage such as overcharging, over-discharging, overheating, and short circuit, the battery pack life is extended to ensure the safe and stable operation of the entire energy storage system. The power conversion system (Power Conversion System, PCS) is one of the core components of the energy storage system, responsible for converting direct current (DC) into alternating current (AC) or converting alternating current into direct current to achieve the storage and release of electrical energy. The energy management system (Energy Management System, EMS) is a key component used to monitor, control and optimize the overall performance of the energy storage system, responsible for managing the energy exchange between the energy storage system and the power grid, and ensuring the efficiency, economy and safety of the system operation.

[0055] In addition to the above structure, the energy storage device also includes an electrical system and a thermal management system, among which the electrical system includes all electrical components and circuits inside the energy storage device, such as the series and parallel connections between the cells, the interface with the inverter or charger, the connection equipment with the power grid or load, the control circuit, etc. The electrical system ensures efficient power conversion and transmission between the energy storage device and the external power supply or load. The thermal management system is a key system to ensure that the battery pack operates within the appropriate temperature range. It monitors and controls the internal temperature of the battery pack through components such as radiators, coolants, fans, and thermistors. When the battery generates heat during the charging and discharging process, the thermal management system can dissipate heat in a timely and effective manner to prevent the battery from overheating and causing performance degradation or safety problems.

[0056] The battery pack for providing stable power output is composed of battery cells connected in series, in parallel, or in series and in parallel. The battery cells connected in series can increase the total voltage of the battery pack, and the battery cells connected in parallel can increase the total capacity of the battery pack. The arrangement of the battery cells can be selected according to the voltage and capacity requirements of the battery pack, and is not limited here.

[0057] In some embodiments, the battery cell generally includes a top cover structure 1, a bare battery cell 2 and a shell 3. Among them, the bare battery cell 2 is the core component of the battery cell, responsible for storing and releasing electrical energy, and is usually composed of positive electrode materials, negative electrode materials, electrolytes and diaphragms; the shell 3 is the external packaging of the battery cell, usually made of materials such as metal or plastic, which can provide physical protection to prevent the internal bare battery cell 2 from being mechanically damaged, and at the same time isolate the internal bare battery cell 2 from the external environment to prevent moisture intrusion; the top cover structure 1 is responsible for connecting the bare battery cell 2 with the external circuit and providing a certain degree of protection. During the production and assembly process, the bare battery cell 2 is placed inside the shell 3 and fixed to the bottom of the shell 3 by screws, snaps and other fixing devices, and the top cover structure 1 is connected to the top of the shell 3 by welding, bolting and the like, thereby assembling the battery cell.

[0058] The bottom surface of the top cover structure 1 is provided with a connection area 14, that is, the bottom of the lower plastic of the top cover structure 1 is provided with a connection area 14, and the distance between the connection area 14 and the center of the bottom surface of the top cover structure 1 is less than the distance between the edge of the top cover structure 1 and the center of the bottom surface of the top cover structure 1. Specifically, the connection area 14 is arranged at a certain distance from the top cover structure 1, and the connection area 14 is an annular part arranged on the inner side of the lower plastic, specifically including a first area 141 arranged relatively along the width direction of the battery cell, and a second area 142 arranged relatively along the length direction of the battery cell. The first area 141 and the second area 142 overlap at the corner area close to the lower plastic. In this application, the width of the first area 141 and the second area 142, as well as the distance between the annular part and the edge of the lower plastic can be selected according to actual needs and are not limited here.

[0059] The battery cell also includes an insulating film 4 wrapped around the outside of the bare battery cell 2. The insulating film 4 includes a film body 41 and an extension 42. The film body 41 is wrapped around the side wall and bottom wall of the bare battery cell 2. The extension 42 is formed by extending upward from the side wall of the film body 41, and is bent toward the center of the top surface of the bare battery cell 2 along the length and width directions of the bare battery cell 2. The extension 42 is located between the connection area 14 and the top surface of the bare battery cell 2 along the height direction of the bare battery cell 2, and the upper surface of the extension 42 is connected to the lower surface of the connection area 14. It can be understood that the main body 111 can be enclosed to form a rectangular box with a receiving cavity, and the bare battery cell 2 is received in the rectangular box, and the top of the bare battery cell 2 is flush with the top of the rectangular box. At this time, the extension 42 is bent again to complete the coating process of the bare battery cell 2.

[0060] The extension portion 42 includes a first extension portion 421 arranged along the width direction of the battery cell and a second extension portion 422 arranged oppositely along the length direction of the battery cell. When the bare battery cell 2 coated with the insulating film 4 is assembled with the shell 3 and the top cover structure 1, the first extension portion 421 is located between the first area 141 and the top surface of the bare battery cell 2, and the upper surface of the first extension portion 421 is connected to the first area 141; the second extension portion 422 is located between the second area 142 and the top surface of the bare battery cell 2, and the upper surface of the second extension portion 422 is connected to the second area 142.

[0061] The width of the first extension portion 421 is 2mm-8mm, the width of the second extension portion 422 is 2mm-6mm, and the width of the first extension portion 421 is greater than the width of the second extension portion 422. Optionally, the width of the first extension portion 421 may be 2mm-8mm, 3mm-7mm, 4mm-8mm or 5mm-6mm, etc., specifically 2mm, 3mm, 4mm, 5mm, 6mm, 7mm and 8mm, etc., or other values ​​within the range, which may be selected according to actual needs and are not limited here; the width of the second extension portion 422 may be 2mm-6mm, 3mm-5mm, 2mm-5mm or 4mm-4.5mm, etc., specifically 2mm, 3mm, 4mm, 5mm and 6mm, etc., or other values ​​within the range, which may be selected according to actual needs and are not limited here. It can be understood that when the width of the first extension portion 421 and the second extension portion 422 are within the above range, when the two are bent inward, a larger connection area can be provided to connect with the first area 141 and the second area 142 respectively, thereby improving the connection stability between the insulating film 4 and the connection area 14, and will not affect the electrical connection between the connecting piece 13 and the bare battery cell 2 during the subsequent assembly process due to excessive coverage of the area on the top wall of the bare battery cell 2; at the same time, the length of the battery cell is greater than the width of the battery cell, so that the connection strength between the first extension portion 421 and the first area 141 is greater than the connection strength between the second extension portion 422 and the second area 142, thereby ensuring the stable installation of the insulating film 4.

[0062] It should be noted that the first region 141 and the second region 142 have an overlapping portion. If an insulating film 4 is set here, the insulating film 4 stacked on the overlapping portion of the first region 141 and the second region 142 includes an upper part and a lower part. The insulating film 4 in the lower part is not easy to be welded with the connecting region 14, which affects the connection effect between the insulating film 4 and the connecting region 14. Therefore, the present application does not set the insulating film 4 at the overlapping portion of the first region 141 and the second region 142 to ensure the connection stability between the insulating film and the first region 141 and the second region 142.

[0063] The insulating film 4 of the above-mentioned coating structure can be a single complete insulating film 4 that covers the outside of the bare battery cell 2, that is, the film body 41 and the extension part 42 are an integrally formed structure; it can also be a combination of multiple incomplete insulating films 4 to cover the outside of the bare battery cell 2, that is, the film body 41 or the extension part 42 is composed of multiple film structures. It can be understood that the insulating film 4 with a split structure can be replaced when part of it is damaged during the assembly process, without replacing the entire insulating film 4, thereby reducing the assembly cost.

[0064] Preferably, the insulating film 4 of the present application consists of two parts. Specifically: the insulating film 4 includes a first part 43 and a second part 44 of the same structure, and the first part 43 and the second part 44 both include a film body 41 and an extension part 42, wherein the first part 43 and the second part 44 both include a second extension part 422 arranged opposite to each other along the length direction of the battery cell, and including a first extension part 421, the first part 43 and the second part 44 can be enclosed to form a rectangular box. The bare battery cell 2 includes a top wall, a bottom wall, a left side wall, a right side wall, a front side wall and a rear side wall; the top wall and the bottom wall are arranged opposite to each other along the height direction of the bare battery cell 2, the left side wall and the right side wall are arranged opposite to each other along the length direction of the bare battery cell 2, and the front side wall and the rear side wall are arranged opposite to each other along the width direction of the bare battery cell 2. The insulating film 4 covers the bottom wall, the left side wall, the right side wall, the front side wall, the rear side wall and part of the top wall of the bare battery cell 2. Among them, the battery cell is divided along the center line of the battery cell, and the first part 43 covers the rear side wall and part of the top wall, part of the left side wall, part of the right side wall and part of the bottom wall of the bare battery cell 2; the second part 44 covers the front side wall and part of the top wall, another part of the left side wall, another part of the right side wall and another part of the bottom wall of the bare battery cell 2; and the membrane body 41 of part of the first part 43 and the second part 44 is overlapped on the top wall, bottom wall, left side wall and right side wall of the bare battery cell 2.

[0065] It should be noted that part of the left side wall, part of the right side wall, part of the bottom wall of the bare battery cell 2 and another part of the left side wall, another part of the right side wall and another part of the bottom wall constitute a complete bottom wall, left side wall and right side wall, and the first part 43 and the second part 44 have overlapping parts when the bottom wall, left side wall and right side wall are covered.

[0066] In some embodiments, the conventional top cover structure includes positive electrode upper plastic, negative electrode upper plastic, lower plastic, explosion-proof plate, explosion-proof valve patch, sealing ring, bare aluminum sheet, negative electrode column, positive electrode column, insulating sheet and connecting sheet.

[0067] Among them, the lower plastic is the bottom part of the top cover structure, which plays the role of insulating part of the top cover structure and the bare battery cell. Specifically, the lower plastic uses insulating materials such as PP and contacts with the shell to ensure insulation between the internal and external circuits of the battery cell and prevent short circuit of the battery cell.

[0068] The lower plastic is provided with a pole mounting position, and the positive pole and the negative pole of the cylindrical structure are installed on the lower plastic. The negative pole and the positive pole are often made of materials with good conductivity. For example, the positive pole can be made of aluminum or aluminum alloy, and the negative pole can be made of copper or copper alloy, aluminum or aluminum alloy, etc. The two have the same structure and serve as the external interface of the battery cell to connect the internal pole ear of the battery cell with the external circuit.

[0069] The connecting piece is used to provide a reliable electrical connection, connecting the tabs of the bare battery cell to the bottom of the positive and negative poles of the battery pack. It is usually made of materials with good conductivity such as copper and its alloys. While having a certain mechanical strength, it can ensure that the current can pass smoothly.

[0070] The plastic on the positive electrode covers the top of the positive electrode column where the bare aluminum sheet is exposed, and plays the role of fixing the positive electrode column and conducting electricity. Specifically, the plastic on the positive electrode adopts conductive materials such as conductive PPS. The above conductive materials enable the plastic on the positive electrode to improve the conductivity between the positive electrode column and the internal circuit of the battery, thereby improving the output power and efficiency of the battery.

[0071] The plastic on the negative electrode covers the top of the bare aluminum sheet of the negative electrode pole, which plays the role of fixing the negative electrode pole and insulation. Specifically, the plastic on the negative electrode adopts insulating materials such as insulating PPS. The above insulating materials can prevent contact short circuit between the negative electrode pole and the shell or other metal parts, provide electrical isolation, improve the safety and stability of the battery cell, and avoid electrical failures caused by accidental contact.

[0072] The bare aluminum sheet is put on the pole by welding (such as ultrasonic welding, laser welding or resistance welding) to form a reliable electrical connection and provide structural support for the positive pole and the negative pole. The bare aluminum sheet has good thermal conductivity, which can help the battery cell dissipate heat and reduce the temperature of the battery pack.

[0073] The explosion-proof disc and explosion-proof valve patch are made of high-temperature resistant materials. The bare aluminum sheet is provided with installation positions for the two. The explosion-proof disc and explosion-proof valve patch are installed at the above installation positions. The two are stacked and used together to ensure that the internal pressure of the shell can be released in time when necessary, thereby ensuring the safety of the battery cell charging and discharging process.

[0074] The sealing ring is installed on the outer periphery of the positive and negative poles and is usually made of elastic materials such as fluororubber. These materials have good sealing performance and aging resistance, and have good sealing performance, which can ensure that the inside of the battery cell is isolated from the external environment and prevent moisture intrusion.

[0075] Different from the conventional top cover structure, the top cover structure 1 provided in the present application specifically includes a sealing ring 15 , a support assembly, a bare aluminum sheet 12 , a negative electrode column, a positive electrode column, an insulating sheet 17 and a connecting sheet 13 .

[0076] Among them, the connecting piece 13 is used to provide a reliable electrical connection, connecting the pole ear of the bare battery cell 2 with the bottom of the positive and negative poles 11 of the battery pack. It is usually made of materials with good conductivity such as copper and its alloys. While having a certain mechanical strength, it can ensure that the current can pass smoothly.

[0077] The bare aluminum sheet 12 is mounted on the pole 11 by welding (such as ultrasonic welding, laser welding or resistance welding) to form a reliable electrical connection. Specifically, the bare aluminum sheet 12 is provided with a mounting hole 121, and the positive pole and the negative pole are inserted into the mounting hole 121 to provide structural support for the positive pole and the negative pole; and the bare aluminum sheet 12 has good thermal conductivity, which can help the battery cell dissipate heat and reduce the temperature of the battery pack.

[0078] The connection area 14 of the top cover structure 1 is arranged on the insulating sheet 17. The insulating sheet 17 is made of a material with good insulation performance, such as PE, PP, etc., and is sleeved on the outer periphery of the pole 11 and located between the bare aluminum sheet 12 and the connecting sheet 13 to isolate the positive and negative poles and prevent short circuit.

[0079] The sealing ring 15 is annular and is sleeved on the outer periphery of the positive and negative poles 11. The sealing ring 15 is inserted into the mounting hole 121 of the plain aluminum sheet 12 and abuts against the wall surface of the mounting hole 121, that is, the sealing ring 15 is located between the positive and negative poles 11 and the wall surface of the mounting hole 121. The sealing ring 15 is usually made of elastic materials such as fluororubber, which have good sealing performance and aging resistance, and have good sealing performance, which can ensure that the inside of the battery cell is isolated from the external environment and prevent moisture from intruding.

[0080] It should be noted that at least part of the wall surface of the mounting hole 121 used in the present application is an inclined surface. Specifically, along the height direction of the pole 11, the cross-sectional shape of the upper part of the mounting hole 121 is an inverted boss structure, and the cross-sectional shape of the lower part of the mounting hole 121 is a boss structure. It can be understood that the cross-sectional shape of the above-mentioned mounting hole 121 is approximately "hourglass-shaped". When the sealing ring 15 is installed in the mounting hole 121, the guiding effect of the inclined surface can better deform the sealing ring 15 and fill it in the mounting hole 121 and fit it tightly, reduce the gap between the sealing ring 15 and the wall surface of the mounting hole 121 and the positive and negative poles, and improve the sealing effect of the sealing ring 15.

[0081] At the same time, the support assembly includes a first pressing block 161 and a second pressing block 162; along the thickness direction of the sealing ring 15, the sealing ring 15 is arranged between the first pressing block 161 and the second pressing block 162. It can be understood that along the height direction of the positive and negative poles 11, the first pressing block 161 and the second pressing block 162 respectively abut against the two sides of the sealing ring 15, and by applying appropriate pressure, the sealing ring 15 is ensured to be in close contact with the pole 11 and the wall surface of the mounting hole 121, thereby achieving good sealing performance. In the actual assembly process, the sealing ring 15 is first placed around the pole 11 and is located between the pole 11 and the mounting hole 121 of the bare aluminum sheet 12, and then the first pressing block 161 and the second pressing block 162 are used to fix it in place. At this time, the first pressing block 161 and the second pressing block 162 ensure that the sealing ring 15 is deformed and filled in the mounting hole 121 and fits tightly by applying appropriate pressure, thereby achieving good sealing performance. The first pressing block 161 and the second pressing block 162 used in the present application are ceramic pressing blocks, and the second pressing block 162 serves as the lower part of the supporting assembly. A corresponding snap-in structure can be set according to the structure of the sealing ring 15, the aluminum sheet 12, the negative pole, the positive pole, the insulating sheet 17 and the connecting sheet 13, so that the assembly of the top cover assembly is more stable. For example, a protruding structure can be set on the top of the second pressing block 162, and a snap-in groove corresponding to the pole can be set at the bottom of the second pressing block 162, which is not limited here.

[0082] It can be understood that the sealing ring 15, the supporting assembly, the bare aluminum sheet 12, the negative electrode column, the positive electrode column, the insulating sheet 17 and the connecting sheet 13 are assembled to form the top cover structure 1 of the present application, which together ensure the reliable electrical connection between the battery cell and the external circuit, and provide the necessary structural support and protection.

[0083] In some embodiments, the pole 11 of the present application includes a main body 111, a first bending portion 112 and a second bending portion 113. The main body 111 is a plate-like structure, and the length of the main body 111 is the length of the pole 11. The present application does not limit the width of the plate-like structure, which can be selected according to the capacity of the battery cell.

[0084] As an optional technical solution of the present application, the length of the positive pole or the negative pole accounts for a proportion of ≥10% of the length of the battery cell. Optionally, the length of the positive pole or the negative pole accounts for a percentage of 15% to 20%, 18 to 25% or 21% to 27% of the length of the battery cell, etc., and can be specifically 10%, 15%, 20%, 25%, 30%, 35% and 40%, etc., or other values ​​within the range, which can be selected according to actual needs and are not limited here. In the present application, the percentage of the length of the positive pole or the negative pole to the length of the battery cell is within the above range, the pole 11 is larger in size, has higher mechanical strength, has lower contact resistance and greater current carrying capacity, and can meet the production needs of large-capacity battery cells; and the larger-sized pole 11 has better heat dissipation performance, which can ensure that the battery cell operates within a safe temperature range. It is understandable that if the length of the pole 11 accounts for too small a proportion of the length of the battery cell, that is, the size of the pole 11 is small, the difficulty of welding and connection is increased, and poor welding may lead to poor contact, affecting the electrical performance and reliability of the battery. The pole 11 with too small size has low mechanical strength, high contact resistance and low current carrying capacity; if the length of the pole 11 accounts for too large a proportion of the length of the battery cell, the overall weight of the battery will be increased, and the manufacturing cost of the battery will be increased. Preferably, the length of the pole 11 accounts for 10% to 30% of the length of the battery cell.

[0085] As another optional technical solution of the present application, the total length of the positive pole and the negative pole accounts for ≥10% of the length of the battery cell. Optionally, the total length of the positive pole and the negative pole accounts for a percentage of 13% to 17%, 18% to 25% or 30% to 36% of the length of the battery cell, etc., and can be specifically 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 55%, 60% and 65%, etc., or other values ​​within the range, which can be selected according to actual needs and are not limited here. In the present application, the total length of the positive pole and the negative pole accounts for a percentage of the length of the battery cell within the above range, the pole 11 is larger in size, has higher mechanical strength, has lower contact resistance and greater current carrying capacity, and can meet the production needs of large-capacity batteries; and the larger pole 11 has better heat dissipation performance, which can ensure that the battery cell operates within a safe temperature range. It is understandable that if the length of the pole 11 accounts for too small a proportion of the length of the battery cell, that is, the size of the pole 11 is small, it increases the difficulty of welding and connection, and poor welding may lead to poor contact, affecting the electrical performance and reliability of the battery. The pole 11 with too small size has low mechanical strength, high contact resistance and low current carrying capacity; if the length of the pole 11 accounts for too large a proportion of the length of the battery cell, it will increase the overall weight of the battery and increase the manufacturing cost of the battery. Preferably, the total length of the positive pole and the negative pole accounts for 10% to 30% of the length of the battery cell.

[0086] Preferably, along the length direction of the battery cell, the length of the pole 11 is 10mm~100mm, optionally, the length of the pole 11 can be 18mm~25mm, 36mm~44mm or 27mm~65mm, etc., specifically 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm and 100mm, etc., or other values ​​within the range, which can be selected according to actual needs and are not limited here. It can be understood that the length of the pole 11 is within the above range, while having a certain mechanical strength, it also has a lower contact resistance and a greater current carrying capacity; and the larger size of the pole 11 has a larger heat dissipation area, that is, better heat dissipation performance, which can ensure that the battery cell operates within a safe temperature range.

[0087] In some embodiments, along the height direction of the battery cell, the first bending portion 112 and the second bending portion 113 are respectively located on both sides of the mounting hole 121 of the bare aluminum sheet 12, and extend horizontally along the width direction of the battery cell; along the width direction of the battery cell, the first bending portion 112 and the second bending portion 113 projected on the same straight line extend in opposite directions in the width direction of the battery cell, that is, the first bending portion 112, the main body 111 and the second bending portion 113 projected on the same straight line present a "Z" structure. At the same time, along the length direction of the battery cell, the adjacent first bending portions 112 have opposite bending directions in the width direction of the battery cell, and the adjacent second bending portions 113 have opposite bending directions in the width direction of the battery cell. It can be understood that the pole 11 of the above structure, the first bending portion 112 and the second bending portion 113 are staggered in the length direction, width direction and height direction of the battery cell, which can better fix the connecting sheet 13 and the bare aluminum sheet 12.

[0088] Along the length direction of the battery cell, the width of the first bending portion 112 and the second bending portion 113 is 1mm~10mm, and along the width direction of the battery cell, the extension length of the first bending portion 112 and the second bending portion 113 is 0.5mm~5mm. Optionally, the width of the first bending portion 112 and the second bending portion 113 can be 2mm~5mm, 4mm~7mm, 3mm~9mm, etc., specifically 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm and 10mm, etc., and the extension length of the first bending portion 112 and the second bending portion 113 can be 0.7mm~3mm, 1mm~4mm, 2.5mm~3.5mm, etc., specifically 0.5mm, 1mm, 2mm, 3mm, 4mm, and 5mm, etc., or other values ​​within the range. It can be selected according to actual needs and is not limited here.

[0089] Along the length direction of the battery cell, the spacing distance between adjacent first bending portions 112 and adjacent second bending portions 113 is 0.17mm~3.4mm. Optionally, the spacing distance between adjacent first bending portions 112 and adjacent second bending portions 113 can be 0.18mm~0.95mm, 1.6mm~2.7mm, 1mm~3mm, etc., specifically 0.17mm, 0.67mm, 1.17mm, 1.67mm, 2.17mm, 2.67mm, 3.17mm and 3.4mm, etc., or other values ​​within the range. It can be selected according to actual needs and is not limited here.

[0090] It can be understood that the width and extension length of the first bending portion 112 and the second bending portion 113, and the spacing distance between adjacent first bending portions 112 and adjacent second bending portions 113 are within the above-mentioned range. When the length of the pole 11 is constant, the number of the first extension portion 421 and the second extension portion 422 is ensured to enhance the connection stability between the second bending portion 113 and the connecting plate 13 while reducing the contact resistance between the first bending portion 112 and the second bending portion 113.

[0091] In some embodiments, the connecting piece 13 connected to the second extension portion 422 is used to connect the bare battery cell 2 inside the battery cell and the pole 11. During the charging and discharging process of the battery cell, the connecting piece 13 can carry the current during the charging and discharging process of the battery cell, ensuring that the current can pass stably, and further ensuring that the electric energy generated inside the battery cell can be stably transmitted to the outside of the battery cell.

[0092] The connecting piece 13 of the present application is a rectangular sheet structure, and a plurality of staggered first connecting holes 131 are provided on its surface. The distribution position of the first connecting holes 131 corresponds to the shape of the second bending portion 113, so that the second bending portion 113 of the pole 11 can be snapped into the first connecting hole 131 when the battery cell is assembled, and the second bending portion 113 does not protrude from the surface of the connecting piece 13 away from the bare aluminum sheet 12. It can be understood that the design that the second bending portion 113 does not protrude from the surface of the connecting piece 13 can reduce the influence of the second bending portion 113 on the connection stability between the connecting piece 13 and the bare battery cell 2, and the connection between the connecting piece 13 and the bare battery cell 2 is more stable, reducing the risk of loosening or falling off of the connecting piece 13 and the bare battery cell 2 due to poor contact, ensuring that the battery cell still maintains a good electrical connection under vibration or impact environment, and extending the service life of the battery cell.

[0093] At the same time, compared with the conventional adapter plate, the welding position 132 of the rectangular sheet-shaped connecting piece 13 can be directly welded or connected to the pole ear of the bare battery cell 2, which simplifies the connection process, does not require additional connectors or joints, and reduces the intermediate links in the installation process of the connecting piece 13; and the connection distance between the pole ear and the connecting piece 13 is shortened, further reducing the resistance loss during current transmission.

[0094] In some embodiments, the battery pack also includes a tab 5, and the battery cell is connected to the external circuit via the tab 5, which plays a role in fixing the battery cell, ensuring that the battery cell is firmly connected to other components during the packaging process, and can also stably transmit the electric energy generated inside the battery cell to the external circuit. During the charging and discharging process of the battery cell, the tab 5 can carry the current during the charging and discharging process of the battery cell, ensuring that the current can pass stably.

[0095] The bar piece 5 of the present application is a rectangular sheet structure, similar to the structure of the connecting piece 13, and a plurality of staggered second connecting holes 51 are provided on its surface, and the distribution position of the second connecting holes 51 corresponds to the shape of the first bending portion 112, so that the first bending portion 112 of the pole 11 can be snapped into the second connecting hole 51 when the battery cell is assembled, and the first bending portion 112 does not protrude from the surface of the bar piece 5 away from the bare aluminum sheet 12.

[0096] It can be understood that the connection between the connecting piece 13 and the second extension part 422, and the bar piece 5 and the first extension part 421 of the present application adopt the above-mentioned clamping connection method, which can ensure the connection stability between the pole 11 and the connecting piece 13 and the bar piece 5.

[0097] Furthermore, after the first bending portion 112 is engaged with the second connecting hole 51 of the bar piece 5 and the second bending portion 113 is engaged with the first connecting hole 131 of the connecting piece 13, the edges where the first bending portion 112 abuts against the bar piece 5 and the edges where the second bending portion 113 abuts against the connecting piece 13 can be welded, thereby further improving the connection stability between the first bending portion 112 and the bar piece 5 and the second bending portion 113 and the connecting piece 13.

[0098] In some embodiments, the present application further provides a process for preparing a battery cell, including an assembly process of a top cover structure 1, and the assembly process of the top cover structure 1 includes:

[0099] Step S10, preparing the pole 11, the bare aluminum sheet 12 and the connecting sheet 13; wherein the pole 11 includes a main body 111, a first extension portion 421 and a second extension portion 422, and along the height direction of the battery cell, the first extension portion 421 and the second extension portion 422 are respectively arranged at two ends of the main body 111; the bare aluminum sheet 12 is provided with a mounting hole 121, and the connecting sheet 13 is provided with staggered connecting holes;

[0100] Step S20, the main body 111 of the pole 11 is inserted into the mounting hole 121 of the bare aluminum sheet 12, and the first extension portion 421 is bent to form a first bending portion 112, and the second extension portion 422 is bent to form a second bending portion 113; wherein the first bending portion 112 and the second bending portion 113 are bent in opposite directions in the width direction of the battery cell; and along the length direction of the battery cell, the bending directions of adjacent first bending portions 112 in the width direction of the battery cell are opposite, and the bending directions of adjacent second bending portions 113 in the width direction of the battery cell are opposite;

[0101] Step S30 , the first connection hole 131 of the connection sheet 13 is clamped with the second bending portion 113 of the pole 11 , and the second bending portion 113 does not protrude from the surface of the connection sheet 13 away from the bare aluminum sheet 12 .

[0102] In step S10, the first extension portion 421 and the second extension portion 422 are not bent, that is, the main body 111, the first extension portion 421 and the second extension portion 422 are located in the same plane, the pole 11 is a plate-like structure, the first extension portion 421 is spaced apart on one side of the main body 111 along the height direction, and the second extension portion 422 is spaced apart on the other side of the main body 111 along the height direction.

[0103] In step S20, the pole 11 is a plate-like structure, and at least part of the wall surface of the mounting hole 121 is an inclined surface. The pole 11 can pass through the mounting hole 121 of the bare aluminum sheet 12, so that the bare aluminum sheet 12 is sleeved on the outer periphery of the main body 111. At the same time, an annular insulating sealing ring 15 is arranged between the outer wall surface of the main body 111 and the mounting hole 121. The sealing ring 15 abuts against the inclined surface where the mounting hole 121 is located, and along the height direction of the pole 11, the first pressing block 161 and the second pressing block 162 are respectively arranged on both sides of the sealing ring 15, that is, the sealing ring 15, the first pressing block 161 and the second pressing block 162 are sleeved on the outer periphery of the pole 11, and are stacked along the height direction of the pole 11. The first pressing block 161 and the second pressing block 162 ensure the close contact between the sealing ring 15 and the pole 11 and the housing 3 by applying appropriate pressure, thereby achieving good sealing performance of the sealing ring 15. ;

[0104] After the first pressing block 161 and the second pressing block 162 are installed, a force is applied to the first extension portion 421 and the second extension portion 422 so that the two are bent to form the first bending portion 112 and the second bending portion 113. It can be understood that after the first bending portion 112 and the second bending portion 113 are formed, the first pressing block 161 and the second pressing block 162 can be further fixed to the sealing ring 15.

[0105] In step S30, the first connection hole 131 of the connection sheet 13 is snapped into the second bending portion 113 of the pole 11. The specific process is: the first connection hole 131 on the connection sheet 13 and the bending structure formed by the second bending portion 113 are spatially aligned and snapped into place.

[0106] After step S30, step S40 is also included: welding the second bent portion 113 of the pole 11 to the edge of the first connection hole 131 of the connecting piece 13, and welding the first bent portion 112 of the pole 11 to the edge of the second connection hole 51 of the bar piece 5. It can be understood that by fixing the second bent portion 113 to the connecting piece 13 and the first bent portion 112 to the bar piece 5 by welding, the connection stability of the first bent portion 112 to the bar piece 5 and the second bent portion 113 to the connecting piece 13 can be further improved.

[0107] After step S30, an assembly is obtained, and then the positive electrode plastic, the negative electrode plastic, the lower plastic, the explosion-proof disk, the explosion-proof valve patch and the assembly are connected to complete the assembly process of the top cover structure 1. It should be noted that the structure of the positive electrode plastic, the negative electrode plastic and other components can be adjusted according to the shape and size of the pole 11, which is not limited here.

[0108] After step S30, the process of coating the insulating film 4 is also included. The coating process of the insulating film 4 specifically includes:

[0109] Step S40, prepare a bare cell 2, a top cover structure 1 and an insulating film 4; the bare cell 2 includes a top wall, a bottom wall, a left side wall, a right side wall, a front side wall and a rear side wall; the lower plastic of the top cover structure 1 is provided with a connection area 14, and the distance between the connection area 14 and the center of the top cover structure 1 is smaller than the distance between the edge of the top cover structure 1 and the center of the top cover structure 1; the cell also includes an insulating film 4; the insulating film 4 includes a first part 43 and a second part 44 with the same structure, and the first part 43 and the second part 44 are both provided with a film body 41 and an extension part 42.

[0110] Step S50, wrapping the first part 43 and the second part 44 around the bare battery cell 2 along the width direction of the bare battery cell 2, wherein the film body 41 of the first part 43 covers the rear side wall and part of the top wall, part of the left side wall, part of the right side wall and part of the bottom wall of the bare battery cell 2; the film body 41 of the second part 44 covers the front side wall and part of the top wall, another part of the left side wall, another part of the right side wall and another part of the bottom wall of the bare battery cell 2; and the film bodies 41 of parts of the first part 43 and the second part 44 are overlapped on the bottom wall, the left side wall and the right side wall of the bare battery cell 2;

[0111] Step S60, bend the extension portion 42 of the first portion 43 and the second portion 44 toward the center of the top surface of the bare battery cell 2 along the length direction and the width direction of the bare battery cell 2, so that the extension portion 42 is located between the connection area 14 and the top surface of the bare battery cell 2, and the upper surface of the extension portion 42 is connected to the connection area 14.

[0112] After step S60, the process of connecting the insulating film 4 and the connecting area 14 is also included: the extension portion 42 and the connecting area 14 of the top cover structure 1 are connected by hot melt, and then the top cover structure 1 and the shell 3 are welded. At this time, the insulating film 4 will not be squeezed into the welding gap between the shell 3 and the top cover structure 1, so that the insulating film 4 can be prevented from interfering with the welding between the top cover structure 1 and the shell 3, reducing the situation of poor welding, ensuring the sealing and electrical connection effect of the battery pack, and then improving the working performance and safety of the battery pack.

[0113] After the above steps S40 to S60, the bare cell 2 can be connected to the top cover structure 1, and the bottom of the bare cell 2 is connected to the bottom support sheet 21 and then the bare cell 2 is assembled into the shell 3. The shell 3 and the top cover are welded to complete the assembly process of the cell.

[0114] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the drawings. Any changes made according to the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the protection scope of the present invention.

Claims

1. A battery cell, comprising a top cover structure, characterized in that: The top cover structure comprises: A pole, comprising a main body, a first bending portion and a second bending portion; wherein, along the height direction of the battery cell, the first bending portion and the second bending portion are respectively arranged on both sides of the main body, and extend horizontally along the width direction of the battery cell; along the width direction of the battery cell, the first bending portion and the second bending portion projected on the same straight line extend in opposite directions in the width direction of the battery cell; along the length direction of the battery cell, the adjacent first bending portions have opposite bending directions in the width direction of the battery cell, and the adjacent second bending portions have opposite bending directions in the width direction of the battery cell; the length of the pole accounts for ≥10% of the length of the battery cell; The bare aluminum sheet is provided with a mounting hole, the main body of the pole is inserted into the mounting hole, and along the height direction of the battery core, the first bending portion and the second bending portion are respectively located on both sides of the mounting hole; The connecting sheet is provided with first connecting holes which are staggered, the second bent portion of the pole is engaged with the first connecting hole, and the second bent portion does not protrude from the surface of the connecting sheet away from the bare aluminum sheet.

2. The battery cell according to claim 1, characterized in that: Along the length direction of the battery core, the length of the pole is 10mm~100mm.

3. The battery cell according to claim 1, characterized in that: Along the length direction of the battery core, the width of the first bending portion and the second bending portion is 1 mm to 10 mm.

4. The battery cell according to claim 1, characterized in that: Along the width direction of the battery core, the extension lengths of the first bending portion and the second bending portion are 0.5 mm to 5 mm.

5. The battery cell according to claim 1, characterized in that: Along the length direction of the battery core, the spacing distance between adjacent first bending portions is 0.17 mm to 3.4 mm, and the spacing distance between adjacent second bending portions is 0.17 mm to 3.4 mm.

6. The battery cell according to claim 1, characterized in that: The connecting piece is clamped and then welded to the second bent portion.

7. A process for preparing a battery cell, including an assembly process of a top cover structure, characterized in that: The assembly process of the top cover structure includes: Prepare a pole, a bare aluminum sheet and a connecting sheet; wherein the pole comprises a main body, a first extending portion and a second extending portion, and along the height direction of the battery cell, the first extending portion and the second extending portion are respectively arranged at two ends of the main body; the bare aluminum sheet is provided with a mounting hole, and the connecting sheet is provided with a staggered first connecting hole; The main body of the pole is inserted into the mounting hole of the bare aluminum sheet, and the first extension portion is bent to form a first bending portion, and the second extension portion is bent to form a second bending portion; wherein the first bending portion and the second bending portion have opposite bending directions in the width direction of the battery cell; and along the length direction of the battery cell, the adjacent first bending portions have opposite bending directions in the width direction of the battery cell, and the adjacent second bending portions have opposite bending directions in the width direction of the battery cell; The first connection hole of the connection sheet is clamped with the second bent portion of the pole, and the second bent portion does not protrude from the surface of the connection sheet away from the bare aluminum sheet.

8. The process for preparing the battery cell according to claim 7, characterized in that: The assembly process of the top cover structure also includes: The second bent portion of the pole is welded to an edge of the first connecting hole of the connecting sheet.

9. An energy storage device, characterized in that: The energy storage device includes a battery management system, an energy storage inverter, an energy management system and a battery pack, and the battery pack includes a plurality of battery cells as described in any one of claims 1 to 6 or battery cells prepared by the preparation process of the battery cells as described in any one of claims 7 to 8.

10. The energy storage device according to claim 9, characterized in that: The battery pack also includes a tab, the battery cell is connected to the external circuit via the tab, the tab is provided with second connection holes that are staggered, the first bent portion of the pole of the battery cell is engaged with the second connection hole, and the first bent portion does not protrude from the surface of the tab away from the bare aluminum sheet.

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