Battery cell, battery pack and energy storage device

Abstract

The utility model relates to a battery cell, a battery pack and an energy storage device, the battery cell comprises an electrode assembly, an adapter plate and a top cover, the adapter plate is connected with the electrode assembly, and the top cover is connected with one side, far away from the electrode assembly, of the adapter plate. The electrode assembly comprises a positive electrode lug and a negative electrode lug, the adapter sheets comprise a positive electrode adapter sheet and a negative electrode adapter sheet, the positive electrode lug is connected with the positive electrode adapter sheet, the negative electrode lug is connected with the negative electrode adapter sheet, and the connection area between the positive electrode lug and the positive electrode adapter sheet is larger than that between the negative electrode lug and the negative electrode adapter sheet. The resistance between the positive pole lug and the positive pole adapter plate can be reduced, and the temperature at the positive pole lug can be reduced in the charging and discharging process of the battery cell, so that the risk of failure at the positive pole lug is reduced.

Description

Technical Field

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

[0002] A plurality of battery cells are arranged in the energy storage device for storing electric energy. The electrode assembly in the battery cell is generally formed by winding or stacking the positive electrode tab, the negative electrode tab and the separator. On the same side of the height direction of the electrode assembly, the positive electrode tab and the negative electrode tab are provided with tabs, and the positive electrode tab and the negative electrode tab are formed after the electrode assembly is wound. The positive electrode tab and the negative electrode tab are connected to the positive electrode post and the negative electrode post on the top cover through the adapter, so that the electrode assembly can be connected to the outside world through the positive electrode post and the negative electrode post to realize the charging and discharging of the battery cell. The temperature of the battery cell is relatively high during the charging and discharging process of the battery cell. Utility Model Content

[0003] The present application provides a battery cell, a battery pack and an energy storage device for solving the problem of high battery cell temperature during the battery cell charging and discharging process.

[0004] The present application provides a battery cell, which includes:

[0005] Electrode assembly;

[0006] A transfer sheet connected to the electrode assembly;

[0007] A top cover connected to a side of the adapter sheet away from the electrode assembly;

[0008] Among them, the electrode assembly includes a positive electrode tab and a negative electrode tab, the adapter sheet includes a positive electrode adapter sheet and a negative electrode adapter sheet, the positive electrode adapter sheet is connected to the positive electrode tab, and the negative electrode adapter sheet is connected to the negative electrode tab; the connection area between the positive electrode tab and the positive electrode adapter sheet is larger than the area of ​​the connection area between the negative electrode tab and the negative electrode adapter sheet.

[0009] In a possible implementation, a ratio of an area of ​​a connection region between the positive electrode tab and the positive electrode adapter plate to an area of ​​a connection region between the negative electrode tab and the negative electrode adapter plate is 1.1 to 2.

[0010] In a possible implementation, the area of ​​the connection between the positive electrode tab and the positive electrode adapter is 96 mm 2 Up to 216mm 2 ; The length is 16mm to 24mm, and the width is 6mm to 9mm.

[0011] In a possible implementation manner, the number of welding points between the positive electrode tab and the positive electrode adapter is 17 to 40.

[0012] In a possible implementation manner, the relationship between the connection area S1 between the positive electrode tab and the positive electrode adapter and the capacity C of the battery cell is: 6S1-318≤C≤8S1-318.

[0013] In a possible implementation manner, the area of ​​the connection region between the negative electrode tab and the negative electrode adapter is 48 mm 2 Up to 160mm 2 ; The length is 12mm to 20mm, and the width is 4mm to 8mm.

[0014] In a possible implementation manner, the number of welding points between the negative electrode tab and the negative electrode adapter is 15 to 30.

[0015] In a possible implementation manner, the relationship between the connection area S2 between the negative electrode tab and the negative electrode adapter and the capacity C of the battery cell is: 12S2-318≤C≤13S2-318.

[0016] In a possible implementation, the battery core includes a heat sink, and the heat sink is located on a side where the adapter plate and the electrode assembly are close to each other and / or a side where the adapter plate and the electrode assembly are far away from each other.

[0017] An embodiment of the present application further provides a battery pack, comprising a plurality of battery cells, wherein the battery cells are any of the battery cells described above.

[0018] An embodiment of the present application further provides an energy storage device, which includes a plurality of battery packs, and the battery packs are the above-mentioned battery packs.

[0019] The present application relates to a battery cell, a battery pack and an energy storage device, wherein the battery cell comprises an electrode assembly, a transfer sheet and a top cover, wherein the transfer sheet is connected to the electrode assembly, and the top cover is connected to a side of the transfer sheet away from the electrode assembly. The electrode assembly comprises a positive electrode tab and a negative electrode tab, and the transfer sheet comprises a positive electrode transfer sheet and a negative electrode transfer sheet, wherein the positive electrode tab is connected to the positive electrode transfer sheet, and the negative electrode tab is connected to the negative electrode transfer sheet, and the connection area between the positive electrode tab and the positive electrode transfer sheet is greater than the connection area between the negative electrode tab and the negative electrode transfer sheet, which can reduce the resistance between the positive electrode tab and the positive electrode transfer sheet, and during the process of charging and discharging the battery cell, the temperature at the positive electrode tab can be reduced, thereby reducing the risk of failure at the positive electrode tab.

[0020] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 An exploded diagram of a battery cell provided in an embodiment of the present application;

[0022] Figure 2 A top view of the connection position between the adapter and the electrode assembly provided in an embodiment of the present application;

[0023] Figure 3 An exploded view of a battery pack provided in an embodiment of the present application;

[0024] Figure 4 A schematic diagram of the structure of the energy storage device provided in an embodiment of the present application.

[0025] Reference numerals:

[0026] 1-Electrode assembly;

[0027] 11- positive electrode tab;

[0028] 12- negative electrode tab;

[0029] 13- welding point;

[0030] 2- adapter;

[0031] 21- positive electrode adapter;

[0032] 22- negative electrode adapter;

[0033] 3- Top cover;

[0034] 10-battery cell;

[0035] 20-battery pack;

[0036] 201- box body;

[0037] 202-battery module;

[0038] 203-end plate;

[0039] 204-Steel belt;

[0040] 30-Energy storage device.

[0041] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. 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] The battery cell 10 includes an electrode assembly 1, a transfer sheet 2 and a top cover 3. The electrode assembly 1 is used to store electrical energy and has a tab. One side of the transfer sheet 2 is connected to the tab and the other side is connected to the top cover 3. The top cover 3 is provided with a pole for connecting to external equipment to charge and discharge the battery cell 10. The electrode assembly 1 includes a positive electrode sheet, a negative electrode sheet and a separator. The separator is located between the positive electrode sheet and the negative electrode sheet, and then the electrode assembly 1 is formed by winding. The positive electrode sheet is provided with a positive electrode ear 11 protruding toward the side close to the adapter sheet 2, and the negative electrode sheet is provided with a negative electrode ear 12 protruding toward the side close to the adapter sheet 2. The adapter sheet 2 includes a positive electrode adapter sheet 21 and a negative electrode adapter sheet 22. The positive electrode ear 11 is electrically connected to the positive electrode adapter sheet 21 through laser welding technology, and the negative electrode ear 12 is electrically connected to the negative electrode adapter sheet 22 through laser welding technology, so that the electrode assembly 1 is connected to the top cover 3 through the positive electrode ear 11 and the negative electrode ear 12 to complete the charging and discharging of the battery cell 10. Among them, the positive electrode plate is usually an aluminum plate, and the negative electrode plate is usually a copper plate. Since the resistance of the aluminum plate is greater than that of the copper plate, the overcurrent resistance between the positive electrode tab 11 and the positive electrode adapter plate 21 is greater than the overcurrent resistance between the negative electrode tab 12 and the negative electrode adapter plate 22. During the charging and discharging process of the battery cell 10, the heat generated at the positive electrode tab 11 will be greater than the heat generated at the negative electrode tab 12, resulting in a greater risk of failure at the positive electrode tab 11.

[0048] like Figure 1 and Figure 2As shown, an embodiment of the present application provides a battery cell 10, which increases the area of ​​the connection region between the positive electrode tab 11 and the positive electrode adapter plate 21, so that the area of ​​the connection region between the positive electrode tab 11 and the positive electrode adapter plate 21 is larger than the area of ​​the connection region between the negative electrode tab 12 and the negative electrode adapter plate 22.

[0049] Increasing the area of ​​the connection region between the positive electrode tab 11 and the positive electrode adapter 21 can reduce the resistance between the positive electrode tab 11 and the positive electrode adapter 21. During the charging and discharging process of the battery cell 10, the temperature at the positive electrode tab 11 can be reduced, thereby reducing the risk of failure at the positive electrode tab 11.

[0050] In a possible embodiment, the tab is connected to the adapter 2 by laser welding technology to form a connection area, so that the tab is electrically connected to the adapter 2. The ratio of the connection area S1 between the positive tab 11 and the positive adapter 21 to the connection area S2 between the negative tab 12 and the negative adapter 22 is 1.1 to 2.

[0051] The positive electrode tab 11 is an aluminum sheet, and the resistivity of the aluminum sheet is 2.83×10 -8 The negative electrode tab 12 is a copper sheet, and the resistivity of the copper sheet is 1.75×10 -8The resistance of the conductor is proportional to the resistivity. The resistivity of the aluminum sheet is relatively large, resulting in a relatively large resistance between the positive electrode tab 11 and the positive electrode adapter 21. If the connection area S1 between the positive electrode tab 11 and the positive electrode adapter 21 is consistent with the connection area S2 between the negative electrode tab 12 and the negative electrode adapter 22, during the charging and discharging process of the battery cell 10, the temperature at the positive electrode tab 11 is relatively high, making the battery cell 10 prone to failure. If the ratio of the connection area S1 between the positive electrode tab 11 and the positive electrode adapter sheet 21 to the connection area S2 between the negative electrode tab 12 and the negative electrode adapter sheet 22 is less than 1.1, the difference between the connection area S1 between the positive electrode tab 11 and the positive electrode adapter sheet 21 and the connection area S2 between the negative electrode tab 12 and the negative electrode adapter sheet 22 is relatively small, resulting in the resistance between the positive electrode tab 11 and the positive electrode adapter sheet 21 being greater than the resistance between the negative electrode tab 12 and the negative electrode adapter sheet 22. During the charging and discharging process of the battery cell 10, there is still a risk of failure at the positive electrode tab 11. If the ratio of the connection area S1 between the positive electrode tab 11 and the positive electrode adapter plate 21 to the connection area S2 between the negative electrode tab 12 and the negative electrode adapter plate 22 is greater than 2, the connection area S1 between the positive electrode tab 11 and the positive electrode adapter plate 21 and the connection area S2 between the negative electrode tab 12 and the negative electrode adapter plate 22 are significantly different, making the connection area between the negative electrode tab and the negative electrode adapter plate 22 too small, resulting in a large resistance between the negative electrode tab 12 and the negative electrode adapter plate 22, and generating higher heat at the negative electrode tab 12, increasing the risk of failure of the battery cell 10, or the connection area between the positive electrode tab 11 and the positive electrode adapter plate 21 is too large, and the area of ​​the adapter plate 2 needs to be increased, which in turn increases the volume of the battery cell 10. Therefore, the ratio of the connection area S1 between the positive electrode tab 11 and the positive electrode adapter plate 21 to the connection area S2 between the negative electrode tab 12 and the negative electrode adapter plate 22 can be 1.1, 1.5, 2, etc., preferably 1.5, which can balance the heat generated at the positive electrode tab 11 and the negative electrode tab 12 during the charging and discharging process of the battery cell 10.

[0052] like Figure 2 As shown, in a possible embodiment, the area of ​​the connection region between the positive electrode tab 11 and the positive electrode adapter 21 is 96 mm 2 Up to 216mm 2 .

[0053] The larger the area of ​​the connection between the positive electrode tab 11 and the positive electrode adapter 21, the smaller the resistance, and the smaller the heat generated at the positive electrode tab 11 during charging and discharging of the battery cell 10. 2 The area of ​​the connection between the positive electrode tab 11 and the positive electrode adapter 21 is small, and its resistance is large. During the charging and discharging process of the battery cell 10, the heat generated at the positive electrode tab 11 is high. If the area of ​​the connection between the positive electrode tab 11 and the positive electrode adapter 21 is greater than 216mm 2The area of ​​the connection between the positive electrode tab 11 and the positive electrode adapter 21 is relatively large, and the area of ​​the positive electrode adapter 21 needs to be further increased, which in turn increases the volume of the battery cell 10. Therefore, the area of ​​the connection between the positive electrode tab 11 and the positive electrode adapter 21 can be 96 mm 2 、156mm 2 、216mm 2 Without increasing the volume of the battery cell 10 , the heat generated at the positive electrode tab 11 can be reduced, and the area of ​​the connection region between the positive electrode tab 11 and the positive electrode adapter 21 can be determined according to the capacity of the battery cell 10 .

[0054] The shape of the connection area between the positive electrode tab 11 and the positive electrode adapter plate 21 can be rectangular, with a length of 16 mm to 24 mm and a width of 6 mm to 9 mm.

[0055] If the length of the connection area between the positive pole tab 11 and the positive electrode adapter 21 is less than 16 mm and the width is less than 6 mm, the connection area between the positive pole tab 11 and the positive electrode adapter 21 will be small, the resistance will increase, and the heat generated at the positive pole tab 11 will be large when the battery cell 10 is charged and discharged, which will cause the battery cell 10 to fail easily. There is an overlapping position between the positive pole tab 11 and the positive electrode adapter 21, and the connection area is located at the overlapping position. If the length of the connection area between the positive pole tab 11 and the positive electrode adapter 21 is greater than 24 mm and the width is greater than 9 mm, the area of ​​the overlapping area between the positive pole tab 11 and the positive electrode adapter 21 needs to be increased, which will increase the volume of the battery cell 10. Therefore, the length of the connection area between the positive electrode tab 11 and the positive electrode adapter 21 can be 16 mm, 20 mm, 24 mm, etc., preferably 20 mm, and the width can be 6 mm, 7 mm, 8 mm, 9 mm, etc., preferably 8 mm. While increasing the area of ​​the connection area between the positive electrode tab 11 and the positive electrode adapter 21, the volume of the battery cell 10 can also be reduced.

[0056] The shape of the connection area between the positive electrode tab 11 and the positive electrode adapter 21 can also be a circle or other shapes. When the size of the positive electrode adapter 21 is constant, the area of ​​the connection area between the positive electrode tab 11 and the positive electrode adapter 21 is increased.

[0057] In a possible embodiment, a welding point 13 is formed by laser welding technology at the overlapping position of the positive electrode tab 11 and the positive electrode adapter plate 21 to connect the positive electrode tab 11 and the positive electrode adapter plate 21, and the number of welding points 13 between the positive electrode tab 11 and the positive electrode adapter plate 21 is 17 to 40.

[0058] The positive pole tab 11 is connected to the positive pole adapter 21 through welding points 13. The area of ​​the connection region increases with the number of welding points 13. Limited by the area of ​​the connection region between the positive pole tab 11 and the positive pole adapter 21, the number of welding points 13 between the positive pole tab 11 and the positive pole adapter 21 needs to be less than or equal to 40. If the number of welding points 13 between the positive pole tab 11 and the positive pole adapter 21 is less than 17, the welding strength between the positive pole tab 11 and the positive pole adapter 21 will be reduced, and the positive pole tab 11 is easily separated from the positive pole adapter 21, resulting in a lower service life of the battery cell 10. Therefore, the number of welding points 13 between the positive pole tab 11 and the positive pole adapter 21 can be 17, 28, 40, etc., to improve the welding strength between the positive pole tab 11 and the positive pole adapter 21.

[0059] In a possible embodiment, as shown in the following table, when the capacity of the battery cell 10 is between 314Ah and 630Ah, the corresponding connection area between the positive electrode tab 11 and the positive electrode adapter 21. The relationship between the connection area S1 between the positive electrode tab 11 and the positive electrode adapter 21 and the capacity C of the battery cell 10 is: 6S1-318≤C≤8S1-318.

[0060] Battery capacity / Ah 314 349 384 419 454 489 524 559 594 630 <![CDATA[Connection area / mm 2 > 92 97 102 107 113 118 123 128 133 138

[0061] The larger the capacity of the battery cell 10 is, the more heat is generated at the positive electrode tab 11 during the charging and discharging process of the battery cell 10. The area of ​​the connection region between the positive electrode tab 11 and the positive electrode adapter 21 increases with the increase in the capacity of the battery cell 10, so that the resistance between the positive electrode tab 11 and the positive electrode adapter 21 of the battery cell 10 with a larger capacity is smaller, thereby reducing the possibility of the battery cell 10 with a larger capacity generating a large amount of heat and causing failure.

[0062] The negative electrode tab 12 in the electrode assembly 1 is connected to the negative electrode adapter 22. Since the resistance of the negative electrode sheet is smaller than that of the positive electrode sheet, the area of ​​the connection between the negative electrode tab 12 and the negative electrode adapter 22 is smaller than the area between the positive electrode tab 11 and the positive electrode adapter 21. In a possible embodiment, the area of ​​the connection between the negative electrode tab 12 and the negative electrode adapter 22 is 52mm 2 Up to 160mm 2 .

[0063] The larger the area of ​​the connection between the negative electrode tab 12 and the negative electrode adapter 22, the smaller the resistance between the negative electrode tab 12 and the negative electrode adapter 22, and the smaller the heat generated at the negative electrode tab 12 during the charging and discharging of the battery cell 10. If the area of ​​the connection between the negative electrode tab 12 and the negative electrode adapter 22 is less than 52mm 2If the area of ​​the connection between the negative electrode tab 12 and the negative electrode adapter 22 is too small, the resistance is large. During the charge and discharge process of the battery cell 10, a large amount of heat will be generated at the negative electrode tab 12, which may easily cause the battery cell 10 to fail. If the area of ​​the connection between the negative electrode tab 12 and the negative electrode adapter 22 is greater than 160mm 2 The area of ​​the connection between the negative electrode tab 12 and the negative electrode adapter 22 is relatively large, and the area of ​​the negative electrode adapter 22 needs to be further increased, which in turn increases the volume of the battery cell 10. Therefore, the area of ​​the connection between the negative electrode tab 12 and the negative electrode adapter 22 can be 52mm 2 , 100mm 2 、160mm 2 Without increasing the volume of the battery cell 10 , the heat generated at the positive electrode tab 11 can be reduced, and the area of ​​the connection region between the negative electrode tab 12 and the negative electrode adapter 22 can be determined according to the capacity of the battery cell 10 .

[0064] The shape of the connection area between the negative electrode tab 12 and the negative electrode adapter plate 22 can be rectangular, and the length of the rectangular connection area is 13 mm to 20 mm, and the width is 4 mm to 8 mm.

[0065] Due to the limitation of the area of ​​the connection between the negative electrode tab 12 and the negative electrode adapter 22, the length of the connection between the negative electrode tab 12 and the negative electrode adapter 22 needs to be no greater than 20 mm, and the width needs to be no greater than 8 mm. If the length of the connection between the negative electrode tab 12 and the negative electrode adapter 22 is less than 13 mm, and the width is less than 4 mm, the connection area between the negative electrode tab 12 and the negative electrode adapter 22 will be smaller, and the resistance will increase. When the battery cell 10 is charged and discharged, the heat generated at the negative electrode tab 12 is large, which makes the battery cell 10 prone to failure.

[0066] The shape of the connection area between the negative electrode tab 12 and the negative electrode adapter plate 22 can also be a circle or other shapes. When the size of the negative electrode adapter plate 22 is constant, the area of ​​the connection area between the negative electrode tab 12 and the negative electrode adapter plate 22 is increased.

[0067] The negative pole tab 12 and the negative pole adapter plate 22 in the motor assembly can be connected by laser welding, and a welding point 13 is formed between the negative pole tab 12 and the negative pole adapter plate 22. The number of welding points 13 in the connection area is 15 to 30.

[0068] The negative electrode tab 12 is connected to the negative electrode adapter 22 through welding points 13 formed by laser welding. Due to the limitation of the area of ​​the connection area, the number of welding points 13 needs to be less than 30. If the number of welding points 13 in the connection area is less than 15, the connection strength between the negative electrode tab 12 and the negative electrode adapter 22 will be reduced. When subjected to external force, the negative electrode tab 12 is easy to fall off, resulting in the battery cell 10 being unable to be used normally, shortening the service life of the battery cell 10. Therefore, the number of welding points 13 between the negative electrode tab 12 and the negative electrode adapter 22 can be 15, 20, 30, etc., to improve the connection strength between the negative electrode tab 12 and the negative electrode adapter 22.

[0069] In a possible embodiment, as shown in the following table, when the capacity of the battery cell 10 is between 314Ah and 630Ah, the corresponding connection area between the negative electrode tab 12 and the negative electrode adapter 22. The relationship between the connection area S2 between the negative electrode tab 12 and the negative electrode adapter 22 and the capacity C of the battery cell 10 is: 12S2-318≤C≤13S2-318.

[0070] Battery capacity / Ah 314 349 384 419 454 489 524 559 594 630 <![CDATA[Connection area / mm 2 > 51 53 56 59 62 65 67 70 37 76

[0071] The larger the capacity of the battery cell 10, the more heat is generated at the negative electrode tab 12 during the charge and discharge process. The area of ​​the connection region between the negative electrode tab 12 and the negative electrode adapter plate 22 increases with the increase in the capacity of the battery cell 10, so that the resistance between the negative electrode tab 12 and the negative electrode adapter plate 22 of the battery cell 10 with a larger capacity is smaller, thereby reducing the possibility of the battery cell 10 with a larger capacity generating a large amount of heat and causing failure.

[0072] In a possible embodiment, the battery cell 10 further includes a heat sink, which may be a heat sink coating or other heat sink structures. The heat sink coating may be a graphite heat sink material, a fluoropolymer, a graphene coating, a powder coating, an inorganic coating, an organic coating, a coating with a specific chemical formula, etc. Graphite heat dissipation materials include natural graphite, artificial graphite, graphene and carbon nanotube heat dissipation film with good thermal conductivity; fluoropolymers include fluoropolymers, carbon nanotubes, oxides, etc., which have good thermal conductivity; graphene coating is a coating made by mixing graphene with other materials, which has good electrical conductivity and thermal conductivity; powder coating is a coating that mixes pigments and resins into powder, which has the advantages of scratch resistance; inorganic coatings are represented by zinc-based chromium salts, which chemically bond with the substrate at high temperature, have strong adhesion and are not easy to peel off; organic coatings achieve corrosion protection by isolating water from direct contact with the substrate; coatings with specific chemical formulas may contain materials such as polytetrafluoroethylene (PTFE), fusible polytetrafluoroethylene (PFA), epoxy resin (EP), nano-silicon dioxide (SiO2), graphite powder and silicon carbide, which can improve the thermal conductivity, hardness and wear resistance of the coating.

[0073] The heat sink can be arranged on the side of the electrode tab away from the adapter 2 in the electrode assembly 1, or on the side of the adapter 2 away from the tab, or between the adapter 2 and the tab, or a random combination of the above three situations. Since the tab and the adapter 2 have a connection area, a laser welding point 13 is arranged in the connection area for connecting the tab and the adapter 2. In order to reduce the influence on the connection strength between the tab and the adapter 2, when the heat sink is arranged between the adapter 2 and the tab, the heat sink is arranged around the connection area.

[0074] When the battery cell 10 is charged and discharged, heat is generated at the connection position between the pole ear and the adapter 2. A heat sink is provided at the connection position between the pole ear and the adapter 2 to absorb the heat generated at the pole ear, thereby reducing the possibility of the battery cell 10 being overheated, which is beneficial to improving the safety and service life of the battery cell 10.

[0075] In a possible embodiment, the battery cell 10 includes at least two electrode assemblies 1, the two electrode assemblies 1 are arranged side by side, and the positive electrode tabs 11 in the two electrode assemblies 1 are connected to the same positive electrode adapter 21. The positive electrode adapter 21 is provided with two connection areas for connecting to the positive electrode tabs 11 in different electrode assemblies 1. Similarly, the negative electrode tabs 12 in the two electrode assemblies 1 are connected to the same negative electrode adapter 22.

[0076] In a possible embodiment, the battery cell 10 further includes a shell, the electrode assembly 1 is placed in the shell, and the top cover 3 is located at the opening of the shell to isolate the internal environment of the battery cell 10 from the external environment.

[0077] The embodiment of the present application also provides a battery pack 20, which may include multiple battery modules, and the multiple battery modules are placed side by side in the box 201 of the battery pack 20. The battery module includes a plurality of battery cells 10 described in any of the above items, and the multiple battery cells 10 are placed side by side, and the multiple battery cells 10 are connected in series or in parallel. End plates 203 are provided at both ends of a row of battery cells 10, which are used to limit the relative positions of the multiple battery cells 10 from both ends. A steel belt 204 is also sleeved on the outside of the multiple battery cells 10 and the end plate 203, which is used to limit the size of the battery cell 10. During the charging and discharging process of the battery cell 10, the possibility of expansion of the battery cell 10 can be reduced, which is beneficial to improve the service life of the battery cell 10.

[0078] The embodiment of the present application also provides an energy storage device 30, which includes a cabinet, an inverter and at least one of the above-mentioned battery packs 20. The cabinet has a receiving cavity, and the inverter and the battery pack 20 are accommodated in the receiving cavity. The inverter is used to convert direct current into alternating current. The inverter has the advantages of high conversion efficiency, fast startup speed, high safety, etc., and can also have the functions of short circuit, overload, over / under voltage and over-temperature protection.

[0079] Some large energy storage boxes may also include a battery management system, which is used to enable the battery pack 20 to operate within a safe working range. The battery management system can control the charging and discharging power of the battery pack 20 according to factors such as ambient temperature, battery status, and power demand, thereby improving the safety of the battery pack 20 and making the working state of the battery pack 20 more reasonable, which is beneficial to improving the battery life and service life of the battery pack 20.

[0080] The present application relates to a battery cell 10, a battery pack 20 and an energy storage device 30. The battery cell 10 includes an electrode assembly 1, a transfer sheet 2 and a top cover 3. The transfer sheet 2 is connected to the electrode assembly 1, and the top cover 3 is connected to the side of the transfer sheet 2 away from the electrode assembly 1. The electrode assembly 1 includes a positive electrode tab 11 and a negative electrode tab 12. The transfer sheet 2 includes a positive electrode transfer sheet 21 and a negative electrode transfer sheet 22. The positive electrode tab 11 is connected to the positive electrode transfer sheet 21, and the negative electrode tab 12 is connected to the negative electrode transfer sheet 22. The area of ​​the connection region between the positive electrode tab 11 and the positive electrode transfer sheet 21 is larger than the area of ​​the connection region between the negative electrode tab 12 and the negative electrode transfer sheet 22, which can reduce the resistance between the positive electrode tab 11 and the positive electrode transfer sheet 21. During the charging and discharging process of the battery cell 10, the temperature at the positive electrode tab 11 can be reduced, thereby reducing the risk of failure at the positive electrode tab 11.

[0081] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, characterized in that: The battery cell comprises: Electrode assembly (1); A transfer sheet (2), the transfer sheet (2) being connected to the electrode assembly (1); A top cover (3), the top cover (3) being connected to a side of the adapter sheet (2) away from the electrode assembly (1); The electrode assembly (1) comprises a positive electrode tab (11) and a negative electrode tab (12); the adapter sheet (2) comprises a positive electrode adapter sheet (21) and a negative electrode adapter sheet (22); the positive electrode adapter sheet (21) is connected to the positive electrode tab (11), and the negative electrode adapter sheet (22) is connected to the negative electrode tab (12); the connection area between the positive electrode tab (11) and the positive electrode adapter sheet (21) is greater than the area of ​​the connection area between the negative electrode tab (12) and the negative electrode adapter sheet (22).

2. The battery cell according to claim 1, characterized in that: The ratio of the area of ​​the connection region between the positive electrode tab (11) and the positive electrode adapter (21) to the area of ​​the connection region between the negative electrode tab (12) and the negative electrode adapter (22) is 1.1 to 2.

3. The battery cell according to claim 1, characterized in that: The area of ​​the connection between the positive electrode tab (11) and the positive electrode adapter (21) is 96 mm 2 Up to 216mm 2 ; The length is 16mm to 24mm, and the width is 6mm to 9mm.

4. The battery cell according to claim 1, characterized in that: The number of welding points (13) between the positive electrode tab (11) and the positive electrode adapter plate (21) is 17 to 40.

5. The battery cell according to claim 1, characterized in that: The relationship between the connection area S1 between the positive electrode tab (11) and the positive electrode adapter (21) and the capacity C of the battery core is: 6S1-318≤C≤8S1-318.

6. The battery cell according to claim 1, characterized in that: The area of ​​the connection between the negative electrode tab (12) and the negative electrode adapter (22) is 48 mm 2 Up to 160mm 2 ; The length is 12mm to 20mm, and the width is 4mm to 8mm.

7. The battery cell according to claim 1, characterized in that: The number of welding points (13) between the negative electrode tab (12) and the negative electrode adapter plate (22) is 15 to 30.

8. The battery cell according to claim 1, characterized in that: The relationship between the connection area S2 between the negative electrode tab (12) and the negative electrode adapter (22) and the capacity C of the battery cell is: 12S2-318≤C≤13S2-318.

9. The battery cell according to any one of claims 1 to 8, characterized in that: The battery core comprises a heat sink, and the heat sink is located on a side where the adapter plate (2) and the electrode assembly (1) are close to each other and / or a side where the adapter plate (2) and the electrode assembly (1) are far away from each other.

10. A battery pack, characterized in that: The battery pack includes a plurality of battery cells, and the battery cells are the battery cells according to any one of claims 1 to 9.

11. An energy storage device, characterized in that: The energy storage device comprises a plurality of battery packs, and the battery packs are the battery packs according to claim 10.

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