Secondary battery and electric device

Abstract

The invention provides a secondary battery and electric equipment, the secondary battery comprises a packaging piece, a first electrode assembly, a second electrode assembly and a supporting piece, the first electrode assembly and the second electrode assembly are stacked in the packaging piece along a first direction, and the length of the second electrode assembly is greater than that of the first electrode assembly along a second direction; the first wall, the second wall and the third wall of the packaging piece are located on the same side of the second electrode assembly in the first direction, the first wall is located on the side, away from the second electrode assembly, of the first electrode assembly, the third wall faces the second electrode assembly, and the third wall is closer to the second electrode assembly than the first wall. The second wall faces the first electrode assembly; at least part of the supporting piece is arranged between the first electrode assembly and the second wall, and in the hot-pressing process, pressure can act on the second electrode assembly through the supporting piece, so that the risk that the cycle performance of the secondary battery is greatly influenced by black spots on the pole piece of the second electrode assembly is reduced.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and in particular, to a secondary battery and an electrical device using the same. Background Art

[0002] With the rapid development of new energy technologies, secondary batteries have been widely used in fields such as electronic devices, electric vehicles, electric two-wheelers, and power tools. As the application of secondary batteries becomes more and more extensive, higher requirements are put forward for the cycling performance of secondary batteries. Summary of the Invention

[0003] Embodiments of this application provide a secondary battery and an electrical device using the same to improve the cycling performance of the secondary battery.

[0004] In a first aspect, embodiments of this application provide a secondary battery. The secondary battery includes a packaging member, a first electrode assembly, and a second electrode assembly. The first electrode assembly and the second electrode assembly are stacked in a first direction within the packaging member. Along a second direction, the length of the second electrode assembly is greater than that of the first electrode assembly. The second electrode assembly has a first portion that extends beyond the first electrode assembly. The first direction is perpendicular to the second direction. The packaging member includes a first wall, a second wall, and a third wall. The first wall, the second wall, and the third wall are located on the same side of the second electrode assembly along the first direction. Along the first direction, the first wall is located on the side of the first electrode assembly facing away from the second electrode assembly. The third wall faces the first portion. Along the first direction, the third wall is closer to the first portion than the first wall. Along the second direction, the second wall faces the first electrode assembly. Wherein, the secondary battery further includes a support member, and at least a part of the support member is disposed between the first electrode assembly and the second wall.

[0005] In one or more of the above optional embodiments, along the second direction, the second wall faces the first electrode assembly with a smaller size, and at least a part of the support member is disposed between the first electrode assembly and the second wall. During the hot pressing process, when pressure is applied to the secondary battery along the first direction, the pressure can act on the area of the second electrode assembly corresponding to the gap between the second wall and the first electrode assembly through the support member, so that the area of the second electrode assembly corresponding to the gap between the second wall and the first electrode assembly can be pressed, which is beneficial to the formation of the bonding force at the electrode interface and the SEI film in this area, and reduces the risk that the electrode sheet in this area appears black spots, which greatly affects the cycling performance of the secondary battery. Therefore, by disposing the support member between the first electrode assembly and the second wall, the support member can transfer the pressure to the area of the second electrode assembly corresponding to the gap between the first electrode assembly and the second wall during the hot pressing process, so that this area of the second electrode assembly can be pressed, which is beneficial to the formation of the bonding force at the electrode interface and the SEI film in this area, reduces the risk of black spots, and is beneficial to improving the cycling performance of the secondary battery.

[0006] In some embodiments of the first aspect of the present application, along the first direction, the distance between the first wall and the electrode tab of the second electrode assembly closest to the first electrode assembly is H, the size of the support member is D, and 1 ≤ H / D ≤ 1.2.

[0007] In one or more of the above optional embodiments, in the first direction, the ratio of the distance between the first wall and the electrode tab of the second electrode assembly closest to the first electrode assembly to the size of the support member is greater than or equal to 1, which facilitates assembling the support member between the first electrode assembly and the second wall. If H / D is less than 1, after assembly, the support member will exert pressure on the second electrode assembly, and the combined action of the pressure generated during assembly and the pressure during hot pressing can easily cause the electrode tab to bear excessive pressure and break. Therefore, H / D > 1 can reduce the risk of the electrode tab breaking due to excessive pressure. In the first direction, the ratio of the distance between the first wall and the electrode tab of the second electrode assembly closest to the first electrode assembly to the size of the support member is less than or equal to 1.2, such that in the first direction, the distance between the support member and the electrode tab of the second electrode assembly closest to the first electrode assembly and / or the distance between the support member and the first wall is small. After applying pressure to the secondary battery in the first direction, when the packaging member, the first electrode assembly, and the second electrode assembly are deformed, the support member can transfer the pressure to the second electrode assembly, reducing the risk that the support member cannot transfer the pressure to the second electrode assembly. Therefore, 1 ≤ H / D ≤ 1.2 not only facilitates assembling the support member between the first electrode assembly and the second wall, reduces the risk of electrode tab damage under pressure, but also enables the support member to effectively transfer pressure between the first wall and the second electrode assembly, reduces the risk of black spots, and improves the safety of the secondary battery.

[0008] In some embodiments of the first aspect of the present application, 0.1 mm ≤ H ≤ 6 mm.

[0009] In one or more of the above optional embodiments, by making the distance between the first wall and the electrode tab of the second electrode assembly closest to the first electrode assembly greater than or equal to 0.1 mm along the first direction, the accommodation cavity of the packaging member for accommodating the first electrode assembly is convenient for processing and forming. By making the distance between the first wall and the electrode tab of the second electrode assembly closest to the first electrode assembly less than or equal to 6 mm along the first direction, the thickness of the first electrode assembly in the packaging member in the first direction is small, so there is more space in the packaging member in the first direction to accommodate the second electrode assembly with a larger size, which is beneficial to improving the energy density of the secondary battery. Therefore, 0.1 mm ≤ H ≤ 6 mm is convenient for processing and forming the accommodation cavity in the packaging member and is beneficial to improving the energy density of the secondary battery.

[0010] In some embodiments of the first aspect of the present application, 0.1 mm ≤ D ≤ 6 mm.

[0011] In one or more of the above optional embodiments, along the first direction, the size of the support member is greater than or equal to 0.1 mm, so that the size of the support member in the first direction is relatively large, which is convenient for manufacturing and forming and is conducive to effectively transmitting pressure between the first wall and the second electrode assembly. Along the first direction, the size of the support member is less than or equal to 6 mm, reducing the space occupied by the support member, which is conducive to the secondary battery having a high energy density. Therefore, 0.1 mm ≤ D ≤ 6 mm, which is not only convenient for the manufacturing and forming of the package, but also enables the secondary battery to have a high energy density.

[0012] In some embodiments of the first aspect of the present application, the first wall is connected to the support member.

[0013] In one or more of the above optional embodiments, by connecting the support member to the first wall, the stability of the support member in the package is better, reducing the risk of the support member shifting during compression, thereby being conducive to providing stable pressure for the two-electrode assembly.

[0014] In some embodiments of the first aspect of the present application, along the first direction, the distance between the electrode tab closest to the first electrode assembly in the second electrode assembly and the support member is H 1 , 0 mm ≤ H 1 ≤ 0.5 mm.

[0015] In one or more of the above optional embodiments, along the first direction, the distance between the electrode tab closest to the first electrode assembly in the second electrode assembly and the support member is greater than or equal to 0 mm and less than or equal to 0.5 mm, so that there is no distance or a small distance between the support member and the electrode tab closest to the first electrode assembly in the second electrode assembly in the first direction. Therefore, after the secondary battery is compressed in the first direction, the support member can act on the second electrode assembly, enabling the support member to effectively transmit pressure between the first wall and the second electrode assembly, reducing the risk of lithium plating due to black spots appearing on the second electrode assembly, and improving the safety of the secondary battery.

[0016] In some embodiments of the first aspect of the present application, the package further includes a first arc transition wall, the first wall and the second wall are connected by the first arc transition wall, and the support member is attached to the inner surface of the first arc transition wall.

[0017] In one or more of the above optional embodiments, the first wall and the second wall are connected by the first arc transition wall, reducing the risk of stress concentration at the transition position between the first wall and the second wall and extending the service life of the package. The support member is attached to the inner surface of the first arc transition wall, making the shape of the support member match the internal space of the package, which is conducive to the uniform force of the second electrode assembly when the support member acts on the second electrode assembly.

[0018] In some embodiments of the first aspect of the present application, the first electrode assembly includes a first positive electrode tab and a first negative electrode tab. The first positive electrode tab and the first negative electrode tab are stacked along a first direction. Along a second direction, both ends of the first negative electrode tab extend beyond both ends of the first positive electrode tab; along the second direction, there is a first gap between the first negative electrode tab and the support member.

[0019] In one or more of the above optional embodiments, both ends of the first negative electrode tab extend beyond both ends of the first positive electrode tab, reducing the risk of lithium plating in the secondary battery and improving the safety performance of the secondary battery. By having a first gap between the first negative electrode tab and the support member in the second direction, the risk of short circuit caused by interference between the support member and the first negative electrode tab is reduced, improving the safety of the secondary battery. The first gap also reserves an installation margin for the installation of the support member, facilitating the installation of the support member between the second wall and the first electrode assembly, and being able to reduce the risk of short circuit caused by interference between the support member and the first negative electrode tab of the first electrode assembly during and after installation, improving the safety of the secondary battery. At the same time, the first gap also provides an expansion space for the support member, reducing the risk of short circuit caused by interference between the support member and the first negative electrode tab after the support member and the first negative electrode tab expand, further improving the safety performance of the secondary battery.

[0020] In some embodiments of the first aspect of the present application, along the second direction, the size of the first gap is L 1 , 0.1 mm ≤ L 1 ≤ 0.5 mm.

[0021] In one or more of the above optional embodiments, the size of the first gap along the second direction is greater than or equal to 0.1 mm, making the size of the first gap larger, reducing the risk of short circuit caused by interference between the support member and the first negative electrode tab, and facilitating the assembly of the support member and providing sufficient space for the expansion of the support member, further reducing the risk of interference between the support member and the first negative electrode tab, improving the safety of the secondary battery. The size of the first gap along the second direction is less than or equal to 0.5 mm, so that the first gap is not too large to cause a decrease in the energy density of the secondary battery and reduces the risk of black spots, improving the safety of the secondary battery. Therefore, 0.1 mm ≤ L 1 ≤ 0.5 mm is beneficial to both improving the safety performance of the secondary battery and improving the energy density and safety of the secondary battery.

[0022] In some embodiments of the first aspect of the present application, 0.3 mm ≤ L 1 ≤ 0.4 mm.

[0023] In one or more of the above optional embodiments, the dimension of the first gap in the second direction is greater than or equal to 0.3 mm, so that the first gap has a larger size, further reducing the risk of short circuit caused by interference between the support member and the first negative electrode plate, facilitating the assembly of the support member and providing sufficient space for the expansion of the support member, further reducing the risk of interference between the support member and the first negative electrode plate, and improving the safety of the secondary battery. The dimension of the first gap in the second direction is less than or equal to 0.4 mm, so that the first gap is not too large to cause a decrease in the energy density of the secondary battery. Therefore, 0.3 mm ≤ L 1 ≤ 0.4 mm, which is beneficial to further improving the safety performance of the secondary battery and also beneficial to improving the energy density of the secondary battery.

[0024] In some embodiments of the first aspect of the present application, along the second direction, the support member contacts the second wall.

[0025] In one or more of the above optional embodiments, along the second direction, the support member contacts the second wall, so that the support member has a larger size in the second direction, which is beneficial to increasing the contact area between the support member and the second electrode assembly, thereby reducing the area of the second electrode assembly that is not under pressure, and further alleviating the problem of black spots appearing in the area corresponding to the gap between the second electrode assembly and the first electrode assembly and the second wall due to non-pressure, which is beneficial to improving the cycling performance of the secondary battery.

[0026] In some embodiments of the first aspect of the present application, along the second direction, there is a second gap between the support member and the second wall.

[0027] In one or more of the above optional embodiments, along the second direction, by having a second gap between the support member and the second wall, the support member does not contact the second wall, which can prevent the problem that the pressure exerted by the support member on the second electrode assembly is blocked due to the generation of friction between the second wall and the support member.

[0028] In some embodiments of the first aspect of the present application, in the second direction, the dimension of the second gap is L 2 , 0 mm ≤ L 2 ≤ 0.3 mm.

[0029] In one or more of the above optional embodiments, by having the second gap between the second wall and the support member in the second direction greater than or equal to 0 mm, the support member does not contact the second wall. This non-contact solution can prevent the problem that the pressure exerted by the support member on the second electrode assembly is blocked due to the generation of friction between the second wall and the support member. By having the second gap between the second wall and the support member in the second direction less than or equal to 0.3 mm, the gap between the second wall and the support member in the second direction is reduced, which is beneficial to improving the energy density of the secondary battery. Therefore, 0 mm < L 2≤0.3 mm. This not only prevents friction from occurring between the second wall and the support member, which would otherwise impede the support member from applying pressure to the second electrode assembly, but also helps improve the energy density of the secondary battery.

[0030] In some embodiments of the first aspect of the present application, the packaging member further includes a second arc transition wall, and the third wall is connected to the second wall through the second arc transition wall; the first electrode assembly includes a first positive electrode tab and a first negative electrode tab, and the first positive electrode tab and the first negative electrode tab are stacked along a first direction. Along a second direction, the first negative electrode tab extends beyond both ends of the first positive electrode tab; along the second direction, the distance between the end of the third wall closest to the second wall and the end of the first positive electrode tab closest to the second wall is L 3 , and the size of the support member is L 4 , 0.6 ≤ L 4 / L 3 ≤ 0.98.

[0031] In one or more of the above optional embodiments, the third wall and the second wall are connected through the second arc transition wall, reducing the risk of stress concentration at the transition position between the third wall and the second wall and extending the service life of the packaging member. By having the ratio of the size of the support member to the distance between the end of the third wall closest to the second wall and the end of the first positive electrode tab closest to the second wall along the second direction greater than or equal to 0.6, the support member can cover a larger area in the second direction, which is beneficial for increasing the contact area between the support member and the second electrode assembly, thereby reducing the area of the second electrode assembly that is not under pressure and further alleviating the problem of black spots appearing in the area of the second electrode assembly corresponding to the gap between the first electrode assembly and the second wall due to lack of pressure, which is beneficial for improving the cycling performance of the secondary battery. By having the ratio of the size of the support member to the distance between the end of the third wall closest to the second wall and the end of the first positive electrode tab closest to the second wall along the second direction less than or equal to 0.98, it is convenient to install the support member between the second wall and the first electrode assembly, and during and after the installation process, the risk of short circuit caused by interference between the support member and the first negative electrode tab of the first electrode assembly can be reduced, improving the safety of the secondary battery. At the same time, it also reserves installation allowance for the installation of the support member and provides expansion space for the support member, reducing the risk of short circuit caused by interference between the support member and the first negative electrode tab after the support member and the first negative electrode tab expand, further improving the safety performance of the secondary battery. Therefore, 0.6 ≤ L 4 / L 3 ≤ 0.98 is beneficial for improving the cycling performance and safety performance of the secondary battery.

[0032] In some embodiments of the first aspect of the present application, 0.5 mm ≤ L 4 ≤ 5.5 mm.

[0033] In one or more of the above optional embodiments, the dimension of the support member in the second direction is greater than or equal to 0.5 mm, such that the dimension of the support member in the second direction is relatively large, facilitating manufacturing and shaping, and enabling the support member to cover a relatively large area in the second direction, which is conducive to increasing the contact area between the support member and the second electrode assembly, thereby reducing the area of the second electrode assembly that is not under pressure, further alleviating the problem of black spots appearing in the area corresponding to the gap between the second electrode assembly, the first electrode assembly, and the second wall due to lack of pressure, and being conducive to improving the cycling performance of the secondary battery. The dimension of the support member in the second direction is less than or equal to 5.5 mm, reducing the space occupied by the support member, which is conducive to the secondary battery having a high energy density. Therefore, 0.5 mm ≤ L 3 ≤ 5.5 mm, which can reduce the manufacturing and shaping difficulty of the support member, increase the acting area of the support member on the second electrode assembly in the second direction, further alleviate the problem of black spots appearing in the area corresponding to the gap between the second electrode assembly, the first electrode assembly, and the second wall due to lack of pressure, and is conducive to improving the energy density of the secondary battery.

[0034] In some embodiments of the first aspect of the present application, 1 mm ≤ L 3 ≤ 6 mm.

[0035] In one or more of the above optional embodiments, along the second direction, the distance between the end of the third wall closest to the second wall and the end of the first positive electrode tab closest to the second wall is greater than or equal to 1 mm, reducing the risk of short circuit of the secondary battery caused by the contact between the first negative electrode tab of the first electrode assembly and the third wall, and improving the safety performance of the secondary battery. Along the second direction, the distance between the end of the third wall closest to the second wall and the end of the first positive electrode tab closest to the second wall is less than or equal to 6 mm, reducing the space within the package that does not accommodate the electrode assembly, which is conducive to improving the energy density of the secondary battery. Therefore, 1 mm ≤ L 3 ≤ 6 mm, which can improve the safety performance and energy density of the secondary battery.

[0036] In some embodiments of the first aspect of the present application, the first electrode assembly includes a first positive electrode tab and a first negative electrode tab, the first positive electrode tab and the first negative electrode tab are stacked along the first direction, and along the third direction, both ends of the first negative electrode tab extend beyond both ends of the first positive electrode tab; along the third direction, the dimension of the support member is not less than the dimension of the first positive electrode tab, and the first direction, the second direction, and the third direction are perpendicular to each other pairwise.

[0037] In one or more of the above optional embodiments, along the third direction, both ends of the first negative electrode tab exceed both ends of the first positive electrode tab, reducing the risk of lithium plating in the secondary battery and improving the safety performance of the secondary battery. By arranging that, along the third direction, the size of the support member is not smaller than that of the first positive electrode tab, the support member covers a larger area in the third direction or is conducive to the support member completely covering the uncompressed area of the second electrode assembly in the third direction, thereby reducing the uncompressed area of the second electrode assembly, and further alleviating the problem of black spots appearing in the area corresponding to the gap between the second electrode assembly and the first electrode assembly and the second wall due to lack of pressure, which is conducive to improving the cycle performance of the secondary battery.

[0038] In some embodiments of the first aspect of the present application, along the third direction, neither end of the first positive electrode tab exceeds either end of the support member.

[0039] In one or more of the above optional embodiments, by arranging that, along the third direction, neither end of the first positive electrode tab exceeds either end of the support member, the support member completely covers the uncompressed area of the second electrode assembly in the third direction, thereby reducing the uncompressed area of the second electrode assembly, and further alleviating the problem of black spots appearing in the area corresponding to the gap between the second electrode assembly and the first electrode assembly and the second wall due to lack of pressure, which is conducive to improving the cycle performance of the secondary battery.

[0040] In some embodiments of the first aspect of the present application, along the third direction, the size of the support member is W 1 , 50 mm ≤ W 1 ≤ 100 mm.

[0041] In one or more of the above optional embodiments, the size of the support member along the third direction is greater than or equal to 50 mm, such that the size of the support member in the third direction is relatively large, facilitating manufacturing and shaping, and enabling the support member to cover a relatively large area in the third direction, which is conducive to increasing the contact area between the support member and the second electrode assembly, thereby reducing the uncompressed area of the second electrode assembly, and further alleviating the problem of black spots appearing in the area corresponding to the gap between the second electrode assembly and the first electrode assembly and the second wall due to lack of pressure, which is conducive to improving the cycle performance of the secondary battery. The size of the support member along the third direction is less than or equal to 100 mm, reducing the space occupied by the support member, which is conducive to the secondary battery having a relatively high energy density. Therefore, 50 mm ≤ W 1 ≤ 100 mm can reduce the manufacturing and shaping difficulty of the support member, increase the acting area of the support member on the second electrode assembly in the third direction, further alleviate the problem of black spots appearing in the area corresponding to the gap between the second electrode assembly and the first electrode assembly and the second wall due to lack of pressure, and is conducive to improving the energy density of the secondary battery.

[0042] In some embodiments of the first aspect of the present application, the material of the support member includes one or more of sodium polyacrylate, polyethylene oxide, polyvinyl alcohol, polypropylene, polyethylene, and polytetrafluoroethylene.

[0043] In one or more of the above optional embodiments, sodium polyacrylate and polyethylene oxide have strong water absorption and water retention properties. The support member made of one or more of sodium polyacrylate and polyethylene oxide can be assembled between the first electrode assembly and the second wall in an unabsorbed state. The support member in the unabsorbed state is small in volume and light in weight, which is convenient for assembly. After injecting the electrolyte into the package, the support member can absorb the electrolyte and serve as a supplement after subsequent electrolyte consumption. Polyvinyl alcohol, polypropylene, polyethylene, and polytetrafluoroethylene have good mechanical strength, which is beneficial for the support member to transfer pressure between the first wall and the second electrode assembly.

[0044] In some embodiments of the first aspect of the present application, the compressive strength of the support member is G, and 20 MPa ≤ G ≤ 40 MPa.

[0045] In one or more of the above optional embodiments, the compressive strength of the support member is greater than or equal to 20 MPa, which is beneficial for the support member to transfer pressure between the first wall and the second electrode assembly. The compressive strength of the support member is less than or equal to 40 MPa, so that when the support member is subjected to pressure in the first direction, it can produce a certain degree of deformation, reducing the risk of the electrode sheet of the second electrode assembly being damaged. Therefore, 20 MPa ≤ G ≤ 40 MPa enables the support member to effectively transfer pressure between the first wall and the second electrode assembly and also reduces the risk of the second electrode assembly being damaged.

[0046] In some embodiments of the first aspect of the present application, the Young's modulus of the support member is E, and 0.5 GPa ≤ E ≤ 3 GPa.

[0047] In one or more of the above optional embodiments, the Young's modulus of the support member is greater than or equal to 0.5 GPa, which is beneficial for the support member to transfer pressure between the first wall and the second electrode assembly. The Young's modulus of the support member is less than or equal to 3 GPa, so that when the support member is subjected to pressure in the first direction, it can produce a certain degree of deformation, reducing the risk of the electrode sheet of the second electrode assembly being damaged. Therefore, 0.5 GPa ≤ E ≤ 3 GPa enables the support member to effectively transfer pressure between the first wall and the second electrode assembly and also reduces the risk of the second electrode assembly being damaged.

[0048] In some embodiments of the first aspect of the present application, the first electrode assembly includes a first positive electrode tab, a first separator, and a first negative electrode tab. The first positive electrode tab and the first negative electrode tab are stacked along a first direction. Along a second direction, the first negative electrode tab extends beyond both ends of the first positive electrode tab, and the first separator extends beyond both ends of the first negative electrode tab. The length of the first separator extending beyond either end of the first negative electrode tab is L 6 , 0.15 mm ≤ L 6 ≤ 2 mm.

[0049] In one or more of the above optional embodiments, by setting the length of the first separator extending beyond either end of the first negative electrode tab to be greater than or equal to 0.15 mm, the risk of lithium plating in the secondary battery can be reduced; by setting the length of the first separator extending beyond either end of the first negative electrode tab to be less than or equal to 2 mm, the risk of interference between the first separator and the support member due to the excessive length of the first separator at the end of the first negative electrode tab is reduced. Thus, during the process of assembling the support member and during the deformation of the support member, the risk of the first separator being inserted reversely and causing the first positive electrode tab and the first negative electrode tab to come into contact and short-circuit is reduced, improving the safety performance of the secondary battery.

[0050] In some embodiments of the first aspect of the present application, the packaging member is a rigid housing, and the electrode tab of the second electrode assembly closest to the first electrode assembly is a negative electrode tab.

[0051] In one or more of the above optional embodiments, the packaging member is a rigid housing with a relatively high hardness. During the hot pressing process, the deformation degree of the packaging member is small, resulting in a relatively large distance between the first electrode assembly and the second wall. Thus, the region of the second electrode assembly corresponding to the gap between the first electrode assembly and the second wall is not under pressure. By providing a support member between the first electrode assembly and the second wall, when pressure is applied to the hard-packed secondary battery along the first direction during the hot pressing process, the pressure can act on the region of the second electrode assembly corresponding to the gap between the second wall and the first electrode assembly through the support member, enabling the region of the second electrode assembly corresponding to the gap between the second wall and the first electrode assembly to be under pressure, which is beneficial to the formation of the interfacial adhesion force and the SEI film here, and reducing the risk of black spots significantly affecting the cycle performance of the hard-packed secondary battery. Therefore, by providing a support member between the first electrode assembly and the second wall, the support member can transfer the pressure to the region of the second electrode assembly corresponding to the gap between the first electrode assembly and the second wall during the hot pressing process, enabling this region of the second electrode assembly to be under pressure, which is beneficial to the formation of the interfacial adhesion force and the SEI film here, reducing the risk of black spots, and being beneficial to improving the cycle performance of the hard-packed secondary battery.

[0052] In a second aspect, an electrical device provided by an embodiment of the present application includes the secondary battery provided by any embodiment of the first aspect.

[0053] In one or more of the above optional embodiments, the secondary batteries provided by any embodiment of the first aspect all have good cycling performance, which is beneficial to improving the power consumption safety and reliability of the electrical equipment powered by the secondary batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the scope.

[0055] Figure 1 An isometric view of the secondary battery provided by some embodiments of the present application;

[0056] Figure 2 is Figure 1 a cross-sectional view taken along the A1-A1 direction in

[0057] Figure 3 A schematic diagram of the first electrode assembly and the second electrode assembly stacked along the first direction provided by some embodiments of the present application;

[0058] Figure 4 A schematic diagram of the first electrode assembly and the second electrode assembly stacked along the first direction as viewed along the second direction provided by some embodiments of the present application;

[0059] Figure 5 is Figure 2 a schematic diagram of the package in

[0060] Figure 6 is Figure 2 an enlarged view of the C1 position in

[0061] Figure 7 A cross-sectional view of the secondary battery provided by some other embodiments of the present application;

[0062] Figure 8 is Figure 7 an enlarged view of the C2 position in

[0063] Figure 9 A cross-sectional view of the secondary battery provided by still some other embodiments of the present application;

[0064] Figure 10 is Figure 9 an enlarged view of the C3 position in

[0065] Figure 11 is Figure 1 a cross-sectional view taken along the A2-A2 direction in

[0066] Icons: 100 - secondary battery; 10 - packaging; 11 - receiving cavity; 111 - first receiving cavity; 112 - second receiving cavity; 1121 - first region; 12 - first wall; 13 - second wall; 14 - third wall; 15 - first arc transition wall; 151 - inner surface of the first arc transition wall; 16 - second arc transition wall; 17 - fourth wall; 18 - third arc transition wall; 19 - fifth wall; 110 - fourth arc transition wall; 1102 - seventh wall; 1103 - eighth wall; 1104 - ninth wall; 20 - first electrode assembly; 21 - first positive electrode tab; 22 - first negative electrode tab; 23 - first separator; 20a - first inner tab; 30 - second electrode assembly; 31 - first part; 32 - second positive electrode tab; 33 - second negative electrode tab; 34 - second separator; 30a - second inner tab; 40 - support; 41 - first mating surface; 50 - insulator; 60 - tab ear; 61 - first positive tab ear; 62 - second positive tab ear; 70 - terminal; X - first direction; Y - second direction; Z - third direction; Q1 - first gap; Q2 - second gap. Detailed Description of the Invention

[0067] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. The components of the embodiments of the present application described and illustrated herein can generally be arranged and designed in a variety of different configurations.

[0068] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application claimed, but merely represents selected embodiments of the present application. It should be noted that, without conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0069] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0070] In the description of the embodiments of the present application, it should be noted that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application. In addition, terms such as "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0071] Currently, from the perspective of the development of the market situation, secondary batteries are more and more widely used. Secondary batteries are widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in multiple fields such as power tools, drones, and energy storage devices. With the continuous expansion of the application fields of secondary batteries, the market demand is also continuously increasing.

[0072] Secondary batteries include wound batteries and laminated batteries. The electrode assembly of the laminated battery includes a plurality of polar opposite electrode sheets alternately stacked. As a kind of laminated battery, the electrode assembly of the stepped battery at least includes a first electrode assembly and a second electrode assembly. The first electrode assembly and the second electrode assembly are stacked along a first direction. Along a second direction, the length of the second electrode assembly is greater than that of the first electrode assembly, and the second direction is perpendicular to the first direction.

[0073] The secondary battery also includes a packaging member. In order to reduce the risk of short circuit of the secondary battery, there is a gap between the outer peripheral surface of the electrode sheet of the electrode assembly and the packaging member, reducing the risk of short circuit caused by the edge of the electrode sheet contacting the packaging member. For the stepped secondary battery, the packaging member includes a first wall, a second wall, and a third wall. The first wall, the second wall, and the third wall are located on the same side of the second electrode assembly along the first direction. Along the first direction, the first wall is located on the side of the first electrode assembly facing away from the second electrode assembly. The third wall faces a first part. Along the first direction, the third wall is closer to the first part than the first wall. Along the second direction, the second wall faces the first electrode assembly. Since in order to reduce the short circuit caused by the contact between the first electrode assembly and the packaging member, there is a gap between the first electrode assembly and the second wall in the second direction Y. When performing a hot pressing process on the stepped secondary battery, the region of the second electrode assembly corresponding to the gap between the first electrode assembly and the second wall in the second direction Y cannot be pressed due to the existence of the gap, affecting the interfacial adhesion force and the formation of the SEI film in this region, resulting in black spots, which greatly affects the cycle performance of the battery.

[0074] Based on the above considerations, in order to improve the cycle performance of the secondary battery, the embodiments of the present application provide a secondary battery, which further includes a support member, and at least a part of the support member is disposed between the first electrode assembly and the second wall.

[0075] Along the second direction, the second wall faces the first electrode assembly with a smaller size, and at least part of the support is disposed between the first electrode assembly and the second wall. During the hot pressing process, when pressure is applied to the secondary battery along the first direction, the pressure can act on the area of the second electrode assembly corresponding to the gap between the second wall and the first electrode assembly through the support, so that the area of the second electrode assembly corresponding to the gap between the second wall and the first electrode assembly can be pressed, which is beneficial to the formation of the adhesive force at the electrode sheet interface and the SEI film in this area, and reduces the risk that the electrode sheet in this area appears black spots and greatly affects the cycle performance of the secondary battery. Therefore, by arranging a support between the first electrode assembly and the second wall, the support can transfer the pressure to the area of the second electrode assembly corresponding to the gap between the first electrode assembly and the second wall during the hot pressing process, so that this area of the second electrode assembly can be pressed, which is beneficial to the formation of the adhesive force at the electrode sheet interface and the SEI film in this area, reduces the risk of black spots, and is beneficial to improving the cycle performance of the secondary battery.

[0076] The secondary battery disclosed in the embodiments of the present application can be but is not limited to being used in power-consuming devices such as electric two-wheel vehicles, electric tools, drones, energy storage devices, etc. The secondary battery with the working conditions of the present application can also be used as the power supply system of the power-consuming device.

[0077] The embodiments of the present application provide a power-consuming device using a secondary battery as a power source. The power-consuming device can be but is not limited to an electronic device, an electric tool, an electric vehicle, a drone, an energy storage device. Among them, the electronic device can include a mobile phone, a tablet computer, a laptop computer, etc., the electric tool can include an electric drill, an electric saw, etc., and the electric vehicle can include an electric car, an electric motorcycle, an electric bicycle, etc.

[0078] As Figure 1 、 Figure 2 As shown, the embodiments of the present application provide a secondary battery 100, which includes a packaging member 10, a first electrode assembly 20 and a second electrode assembly 30. The first electrode assembly 20 and the second electrode assembly are accommodated in the packaging member 10.

[0079] The packaging member 10 can be a rigid housing. For example, the packaging member 10 is a stainless steel shell or an aluminum hard shell, forming a steel shell battery or an aluminum shell battery.

[0080] The packaging member 10 can also be formed of a softer material. For example, the packaging member 10 is an aluminum plastic film or a steel plastic film, forming a soft package battery cell. Exemplarily, as Figure 1 shown, the secondary battery 100 is a hard shell secondary battery.

[0081] As Figures 2 - 4As shown, the first electrode assembly 20 and the second electrode assembly 30 are stacked in the first direction X within the package 10. Along the second direction Y, the length of the second electrode assembly 30 is greater than the length of the first electrode assembly 20. The second electrode assembly 30 has a first portion 31 that extends beyond the first electrode assembly 20. The first direction X is perpendicular to the second direction Y.

[0082] The first electrode assembly 20 includes a first positive electrode plate 21, a first negative electrode plate 22, and a first separator 23 that are stacked in the first direction X. Along the first direction X, the first separator 23 is disposed between adjacent first positive electrode plate 21 and first negative electrode plate 22 to insulate and isolate the first positive electrode plate 21 and the first negative electrode plate 22, reducing the risk of contact short circuit between the first positive electrode plate 21 and the first negative electrode plate 22. As Figure 2 , Figure 3 shown, along the second direction Y, the two ends of the first negative electrode plate 22 extend beyond the two ends of the first positive electrode plate 21, reducing the risk of lithium plating in the secondary battery 100 and improving the safety performance of the secondary battery 100. As Figure 4 shown, along the third direction Z, the two ends of the first negative electrode plate 22 extend beyond the two ends of the first positive electrode plate 21, reducing the risk of lithium plating in the secondary battery 100 and improving the safety performance of the secondary battery 100. Among them, the first direction X, the second direction Y, and the third direction Z are perpendicular to each other in pairs.

[0083] As Figure 3 shown, along the second direction Y, the first separator 23 extends beyond the two ends of the first negative electrode plate 22. Along the third direction Z, the first separator 23 extends beyond the two ends of the first negative electrode plate 22 to reduce the risk of short circuit in the secondary battery 100. Exemplarily, along the second direction Y, the length by which the first separator 23 extends beyond either end of the first negative electrode plate 22 is L 6 , 0.15 mm ≤ L 6 ≤ 2 mm. For example, L 6 can be 0.15 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.5 mm, 2 mm, etc.

[0084] The first electrode assembly 20 includes a first outer electrode plate that is farthest from the second electrode assembly 30. The first outer electrode plate can be an electrode plate with an active material layer coated on one side, which is beneficial to reducing the active material that does not contribute to capacity and improving the energy density of the secondary battery 100. Of course, the first outer electrode plate can also be an electrode plate with an active material coated on both sides. The first outer electrode plate can be the first positive electrode plate 21 or the first negative electrode plate 22.

[0085] As Figures 2 - 4As shown, the second electrode assembly 30 includes a second positive electrode tab 32, a second negative electrode tab 33, and a second separator 34 stacked along the first direction X. Along the first direction X, the second separator 34 is disposed between adjacent second positive electrode tab 32 and second negative electrode tab 33 to insulate and isolate the second positive electrode tab 32 and the second negative electrode tab 33, reducing the risk of contact short circuit between the second positive electrode tab 32 and the second negative electrode tab 33. As Figure 3 shown, along the second direction Y, both ends of the second negative electrode tab 33 extend beyond both ends of the second positive electrode tab 32, reducing the risk of lithium plating in the secondary battery 100 and improving the safety performance of the secondary battery 100. As Figure 4 shown, along the third direction Z, both ends of the second negative electrode tab 33 extend beyond both ends of the second positive electrode tab 32, reducing the risk of lithium plating in the secondary battery 100 and improving the safety performance of the secondary battery 100.

[0086] Along the second direction Y, the second separator 34 extends beyond both ends of the second negative electrode tab 33, and along the third direction Z, the second separator 34 extends beyond both ends of the second negative electrode tab 33 to reduce the risk of short circuit in the secondary battery 100.

[0087] Along the first direction X, the first electrode assembly 20 has a first inner tab 20a closest to the second electrode assembly 30, and the second electrode assembly 30 has a second inner tab 30a closest to the first electrode assembly 20. The active layer on at least one side of the first inner tab 20a facing the second inner tab 30a has a polarity opposite to that of the active layer on the side of the second inner tab 30a facing the first inner tab 20a. The second inner tab 30a can be a positive electrode tab or a negative electrode tab. Figure 3 、 Figure 4 shows the case where the tab closest to the first electrode assembly 20 in the second electrode assembly 30 is a negative electrode tab.

[0088] The second electrode assembly 30 includes a second outer tab farthest from the first electrode assembly 20. The second outer tab can be a tab with an active material layer coated on one side, which is beneficial to reducing the active material that does not contribute to the capacity and improving the energy density of the secondary battery 100. Of course, the second outer tab can also be a tab with an active material layer coated on both sides. The second outer tab can be the second positive electrode tab 32 or the second negative electrode tab 33.

[0089] The separator insulates and separates two tabs with opposite polarities, reducing the risk of short circuit in the secondary battery 100. The material of the separator can include PP (polypropylene) or PE (polyethylene), etc.

[0090] For the first electrode assembly 20 and the second electrode assembly 30, the positive electrode plate includes a positive current collector and a positive active material layer. The positive active material layer is disposed on at least one side of the positive current collector. The material of the positive current collector may include aluminum, and the positive active material may be lithium cobaltate, lithium iron phosphate, ternary lithium, lithium manganate, etc. The negative electrode plate includes a negative current collector and a negative active material layer. The negative active material layer is disposed on at least one side of the negative current collector. The material of the negative current collector may include copper, and the negative active material may be carbon or silicon, etc.

[0091] As Figures 2 - 4 shown, along the second direction Y, at one end where the second electrode assembly 30 extends beyond the first electrode assembly 20, the second electrode assembly 30 has a first portion 31 that extends beyond the first electrode assembly 20, and the other ends of the first electrode assembly 20 and the second electrode assembly 30 are flush. Along the third direction Z, the two ends of the first electrode assembly 20 and the two ends of the second electrode assembly 30 may be respectively flush.

[0092] It should be noted that in the first electrode assembly 20, along the second direction Y, the sizes of the first positive electrode plate 21 and the first negative electrode plate 22 are both smaller than the size of the first separator 23. Along the third direction Z, the sizes of the first positive electrode plate 21 and the first negative electrode plate 22 are both smaller than the size of the first separator 23. Therefore, along the second direction Y, the two ends of the first electrode assembly 20 may be the two ends of the first separator 23 in the first electrode assembly 20 along the second direction Y. Along the third direction Z, the two ends of the first electrode assembly 20 may be the two ends of the first separator 23 in the first electrode assembly 20 along the third direction Z.

[0093] In the second electrode assembly 30, along the second direction Y, the sizes of the second positive electrode plate 32 and the second negative electrode plate 33 are both smaller than the size of the second separator 34. Along the third direction Z, the sizes of the second positive electrode plate 32 and the second negative electrode plate 33 are both smaller than the size of the second separator 34. Therefore, along the second direction Y, the two ends of the second electrode assembly 30 may be the two ends of the second separator 34 in the second electrode assembly 30 along the second direction Y. Along the third direction Z, the two ends of the second electrode assembly 30 may be the two ends of the second separator 34 in the second electrode assembly 30 along the third direction Z.

[0094] Along the second direction Y, the other ends of the first electrode assembly 20 and the second electrode assembly 30 being flush does not mean absolutely flush. A manufacturing error in the distance between the other ends of the first electrode assembly 20 and the second electrode assembly 30 in the second direction Y is allowed. For example, the distance between the other ends of the first electrode assembly 20 and the second electrode assembly 30 in the second direction Y may differ by ±1 mm.

[0095] Along the third direction Z, the two ends of the first electrode assembly 20 and the two ends of the second electrode assembly 30 are not absolutely flush. Manufacturing errors are allowed in the distance between the two ends of the first electrode assembly 20 in the third direction Z and the two ends of the second electrode assembly 30 in the third direction Z. For example, the distance between one end of the first electrode assembly 20 and the corresponding end of the second electrode assembly 30 in the third direction Z may differ by ±1 mm.

[0096] With reference to Figure 1 、 Figure 4 、 Figure 5 shown, the secondary battery 100 further includes pole lugs 60, and the pole lugs 60 protrude from the second electrode assembly 30 along the third direction Z.

[0097] The secondary battery 100 includes two pole lugs 60, and the two pole lugs 60 have opposite polarities.

[0098] Specifically, each first positive electrode plate 21 is connected to a first positive electrode tab 61, and the first positive electrode tab 61 is connected to one end of the first positive electrode plate 21 along the third direction Z. Each second positive electrode plate 32 is connected to a second positive electrode tab 62, and all the first positive electrode tabs 61 and the second positive electrode tabs 62 together form a pole lug 60.

[0099] Each first negative electrode plate 22 is connected to a first negative electrode tab (not shown in the figure), and the first negative electrode tab is connected to one end of the first negative electrode plate 22 along the third direction Z. Each second negative electrode plate 33 is connected to a second negative electrode tab (not shown in the figure), and all the first negative electrode tabs and the second negative electrode tabs together form another pole lug 60.

[0100] It should be noted that the pole lugs 60 protruding from the second electrode assembly 30 along the third direction Z means that the pole lugs 60 protrude from the end of the second electrode assembly 30 along the third direction Z. Among them, the pole lugs 60 may be a straight structure extending along the third direction Z, or the pole lugs 60 may be a bent structure that has been bent at least once. Figure 4 The case where the pole lugs 60 are in a bent structure is shown in

[0101] The two pole lugs 60 may protrude from the same end of the second electrode assembly 30 along the third direction Z, or the two pole lugs 60 may respectively protrude from the opposite ends of the second electrode assembly 30 along the third direction Z.

[0102] A pole post 70 ( Figure 1 、 Figure 11 shown in) may be provided on the package 10, and the pole lugs 60 are electrically connected to the pole post 70.

[0103] The package 10 may be provided with one pole post 70, and the pole post 70 is insulatingly provided on the package 10. One pole lug 60 is electrically connected to the pole post 70, and the other pole lug 60 is electrically connected to the package 10.Figure 1 and Figure 11 shows a case where the package 10 is provided with a terminal 70.

[0104] The package 10 may be provided with two terminals 70, and the two terminals 70 are both insulated and provided on the package 10. One tab 60 is electrically connected to one terminal 70, and the other tab 60 is electrically connected to the other terminal 70.

[0105] With reference to Figure 2 、 Figure 5 , an accommodation cavity 11 is formed inside the package 10. The contour shape of the overall structure formed by the first electrode assembly 20 and the second electrode assembly 30 is the same as that of the accommodation cavity 11. The package 10 can better confine the first electrode assembly 20 and the second electrode assembly 30, reduce the risk of shaking of the first electrode assembly 20 and the second electrode assembly 30 in the accommodation cavity 11 or reduce the degree of shaking, relieve the problem of drop failure, thereby improving the impact resistance and stability of the secondary battery 100 when it is dropped, and reducing the waste of space in the accommodation cavity 11, which is beneficial to improving the energy density of the secondary battery 100.

[0106] The accommodation cavity 11 includes a first accommodation cavity 111 and a second accommodation cavity 112. Along the second direction Y, the size of the second accommodation cavity 112 is larger than that of the first accommodation cavity 111. The first electrode assembly 20 is accommodated in the first accommodation cavity 111, and the second electrode assembly 30 is accommodated in the second accommodation cavity 112.

[0107] Along the second direction Y, the second accommodation cavity 112 has a first region 1121 that extends beyond one end of the first accommodation cavity 111, and the first part 31 of the second electrode assembly 30 is accommodated in the first region 1121.

[0108] Please continue to refer to Figure 2 、 Figure 5 , the package 10 includes a first wall 12, a second wall 13 and a third wall 14. The first wall 12, the second wall 13 and the third wall 14 are located on the same side of the second electrode assembly 30 along the first direction X. Along the first direction X, the first wall 12 is located on the side of the first electrode assembly 20 facing away from the second electrode assembly 30. The third wall 14 is arranged facing the first part 31. Along the first direction X, the third wall 14 is closer to the first part 31 than the first wall 12. Along the second direction Y, the second wall 13 is arranged facing the first electrode assembly 20.

[0109] The first wall 12 and the second wall 13 can be directly connected or indirectly connected. Exemplarily, the package 10 further includes a first arc transition wall 15 that connects the first wall 12 and the second wall 13, that is, the first wall 12 and the second wall 13 are indirectly connected through the first arc transition wall 15. The connection between the first wall 12 and the second wall 13 through the first arc transition wall 15 reduces the risk of stress concentration at the transition position between the first wall 12 and the second wall 13 and extends the service life of the package 10.

[0110] Along the second direction Y, there is a gap between the end of the first electrode assembly 20 close to the second wall 13 and the second wall 13. When observed along the first direction X, a partial area of the first part 31 of the second electrode assembly 30 is arranged corresponding to the gap between the first electrode assembly 20 and the second wall 13.

[0111] The third wall 14 and the second wall 13 can be directly connected or indirectly connected. Exemplarily, the package 10 further includes a second arc transition wall 16 that connects the third wall 14 and the second wall 13, that is, the third wall 14 and the second wall 13 are indirectly connected through the second arc transition wall 16. The connection between the third wall 14 and the second wall 13 through the second arc transition wall 16 reduces the risk of stress concentration at the transition position between the third wall 14 and the second wall 13 and extends the service life of the package 10.

[0112] The package 10 further includes a fourth wall 17 that is connected to the first wall 12. Along the second direction Y, the second wall 13 and the fourth wall 17 are arranged opposite to each other, and the first electrode assembly 20 and the second electrode assembly 30 are located on the same side of the fourth wall 17.

[0113] The fourth wall 17 and the first wall 12 can be directly connected or indirectly connected. Exemplarily, the package 10 further includes a third arc transition wall 18 that connects the first wall 12 and the fourth wall 17, that is, the first wall 12 and the fourth wall 17 are indirectly connected through the third arc transition wall 18. The connection between the first wall 12 and the fourth wall 17 through the third arc transition wall 18 reduces the risk of stress concentration at the transition position between the third wall 14 and the fourth wall 17 and extends the service life of the package 10.

[0114] The package 10 further includes a fifth wall 19 and a fourth arc transition wall 110. The fifth wall 19 is connected to the third wall 14 through the third arc transition wall 18. Along the second direction Y, the fifth wall 19 faces the second electrode assembly 30, and the fifth wall 19 is farther from the first electrode assembly 20 than the second wall 13;

[0115] Among them, the fifth wall 19 and the first wall 12 can be directly connected or indirectly connected. Exemplarily, the package 10 further includes a fourth arc transition wall 110 that connects the fifth wall 19 and the first wall 12, that is, the fifth wall 19 and the first wall 12 are indirectly connected through the fourth arc transition wall 110. The connection between the fifth wall 19 and the first wall 12 through the fourth arc transition wall 110 reduces the risk of stress concentration at the transition position between the fifth wall 19 and the first wall 12 and extends the service life of the package 10.

[0116] The package 10 further includes a seventh wall 1102, an eighth wall 1103, and a ninth wall 1104. The seventh wall 1102 and the eighth wall 1103 are oppositely arranged along the third direction Z, and the ninth wall 1104 and the first wall 12 are oppositely arranged along the first direction X. The two opposite ends of the seventh wall 1102 along the first direction X are respectively connected to the first wall 12 and the ninth wall 1104, and the two opposite ends of the seventh wall 1102 are respectively connected to the first wall 12 and the ninth wall 1104.

[0117] As Figure 2 , Figure 3 shown, in some embodiments, along the second direction Y, the distance between the end of the first positive electrode tab 21 close to the second wall 13 and the end of the second negative electrode tab 33 close to the fourth wall 17 is K 1 , 10 mm ≤ K 1 ≤ 80 mm. Among them, along the second direction Y, the distance between the end of any first positive electrode tab 21 close to the second wall 13 and the end of any second negative electrode tab 33 close to the fourth wall 17 all satisfies 10 mm to 80 mm.

[0118] As Figure 2 shown, in some embodiments, along the second direction Y, the distance between the end of the third wall 14 close to the second wall 13 and the end of the second negative electrode tab 33 close to the fifth wall 19 is K 2 , 10 mm ≤ K 2 ≤ 80 mm. Among them, along the second direction Y, the distance between the end of the third wall 14 close to the second wall 13 and the end of any second negative electrode tab 33 close to the fifth wall 19 all satisfies 10 mm to 80 mm.

[0119] As Figure 6 shown, in some embodiments, the secondary battery 100 further includes a support member 40, and at least a part of the support member 40 is disposed between the first electrode assembly 20 and the second wall 13.

[0120] The support member 40 may be entirely located between the first electrode assembly 20 and the second wall 13. The support member 40 may also have a part located between the first electrode assembly 20 and the second wall 13.

[0121] Viewed along the first direction X, the projection of the support member 40 is located in the first portion 31.

[0122] Along the second direction Y, the second wall 13 faces the first electrode assembly 20 with a smaller size, and at least a part of the support member 40 is disposed between the first electrode assembly 20 and the second wall 13. During the hot pressing process, when pressure is applied to the secondary battery 100 along the first direction X, the pressure can act on the area of the second electrode assembly 30 corresponding to the gap between the second wall 13 and the first electrode assembly 20 through the support member 40, so that the area of the second electrode assembly 30 corresponding to the gap between the second wall 13 and the first electrode assembly 20 can be pressed, which is beneficial to the formation of the pole piece interface adhesion force and the SEI film in this area, and reduces the risk that the pole piece in this area appears black spots and greatly affects the cycle performance of the secondary battery 100. Therefore, by providing the support member 40 between the first electrode assembly 20 and the second wall 13, the support member 40 can transfer the pressure to the area of the second electrode assembly 30 corresponding to the gap between the first electrode assembly 20 and the second wall 13 during the hot pressing process, so that the area of the second electrode assembly 30 can be pressed, which is beneficial to the formation of the pole piece interface adhesion force and the SEI film in this area, reduces the risk of black spots, and is beneficial to improving the cycle performance of the secondary battery 100.

[0123] In the embodiment where the package 10 is a rigid housing, that is, the secondary battery 100 is a hard shell secondary battery, the secondary battery 100 is a hard shell secondary battery. The package 10 of the hard shell secondary battery has a relatively large hardness. During the hot pressing process, the deformation degree of the package 10 of the hard shell secondary battery 100 is small, so that the distance between the first electrode assembly 20 and the second wall 13 is relatively large, and thus the area of the second electrode assembly 30 corresponding to the gap between the first electrode assembly 20 and the second wall 13 is not pressed. By providing the support member 40 between the first electrode assembly 20 and the second wall 13, during the hot pressing process, when pressure is applied to the hard shell secondary battery 100 along the first direction X, the pressure can act on the area of the second electrode assembly 30 corresponding to the gap between the second wall 13 and the first electrode assembly 20 through the support member 40, so that the area of the second electrode assembly 30 corresponding to the gap between the second wall 13 and the first electrode assembly 20 can be pressed, which is beneficial to the formation of the interface adhesion force and the SEI film here, and reduces the risk that black spots appear and greatly affect the cycle performance of the hard package secondary battery 100. Therefore, by providing the support member 40 between the first electrode assembly 20 and the second wall 13, the support member 40 can transfer the pressure to the area of the second electrode assembly 30 corresponding to the gap between the first electrode assembly 20 and the second wall 13 during the hot pressing process, so that the area of the second electrode assembly 30 can be pressed, which is beneficial to the formation of the interface adhesion force and the SEI film here, reduces the risk of black spots, and is beneficial to improving the cycle performance of the hard shell secondary battery 100.

[0124] In an embodiment where, along the second direction Y, the length by which the first separator 23 extends beyond either end of the first negative electrode tab 22 is greater than or equal to 0.15 mm and less than or equal to 2 mm, since the length by which the first separator extends beyond either end of the first negative electrode tab is greater than or equal to 0.15 mm, the risk of lithium plating in the secondary battery can be reduced; and since the length by which the first separator 23 extends beyond a point on the first negative electrode tab 22 close to the second wall 13 is less than or equal to 2 mm, the risk of interference between the first separator 23 and the support member 40 due to an excessive length of the end portion of the first separator 23 relative to the first negative electrode tab 22 can be reduced. Thus, during the process of assembling the support member 40 and during the deformation of the support member 40, the risk of the first separator 23 being inserted backwards and causing contact short - circuit between the first positive electrode tab 21 and the first negative electrode tab 22 can be reduced, improving the safety performance of the secondary battery 100.

[0125] As Figure 6 shown, in some embodiments, the first wall 12 is connected to the support member 40. The first wall 12 and the support member 40 may be adhesively connected. By connecting the support member 40 to the first wall 12, the support member 40 has better stability within the packaging member 10, reducing the risk of the support member 40 shifting during compression, and thus facilitating the provision of a stable pressure to the two - electrode assembly.

[0126] Please continue to refer to Figure 6 , in an embodiment where the first wall 12 and the second wall 13 are connected by the first arc - transition wall 15, the support member 40 is in contact with the inner surface of the first arc - transition wall 15. Specifically, the support member 40 has a first mating surface 41 facing the first arc - transition wall 15, the first mating surface 41 is an arc surface, and at least a partial region of the first mating surface 41 is in contact with the inner surface 151 of the first arc - transition wall. Among them, a partial region of the first mating surface 41 is in contact with a partial region of the inner surface 151 of the first arc - transition wall, or the first mating surface 41 is entirely in contact with the inner surface 151 of the first arc - transition wall.

[0127] The support member 40 being in contact with the inner surface 151 of the first arc - transition wall enables the support member 40 to match the shape of the internal space of the packaging member 10, which is beneficial for the second electrode assembly 30 to be evenly stressed when the support member 40 acts on the second electrode assembly 30.

[0128] The support member 40 and the second wall 13 may be connected to further improve the stability of the support member 40 within the packaging member 10.

[0129] The support member 40 and the second wall 13 may also merely be in contact, which can reduce the assembly difficulty of the secondary battery 100.

[0130] As Figures 6 - 8As shown, in some embodiments, along the first direction X, the distance between the first wall 12 and the electrode tab of the second electrode assembly 30 closest to the first electrode assembly 20 is H, the size of the support member 40 is D, and 1 ≤ H / D ≤ 1.2.

[0131] The electrode tab of the second electrode assembly 30 closest to the first electrode assembly 20 is the second inner electrode tab 30a, and H is the distance between the inner surface of the first wall 12 and the first inner electrode tab 20a.

[0132] As Figure 7 , Figure 8 shown, in some embodiments, an insulating member 50 is provided on the surface of the second inner electrode tab 30a facing the third wall 14 in the first portion 31 to reduce the risk of short circuit of the secondary battery 100. In this case, H is the distance between the inner surface of the first wall 12 and the insulating member 50 facing away from the first inner electrode tab 20a in the first direction X. The insulating member 50 can be an insulating coating or adhesive tape.

[0133] When H / D = 1, along the first direction X, both ends of the support member 40 are in contact with the first wall 12 and the first inner electrode tab 20a respectively. It should be noted that since there is a second separator 34 between the second inner electrode tab 30a and the first electrode assembly 20, the support member 40 is in contact with the second inner electrode tab 30a indirectly through the second separator 34.

[0134] When H / D > 1, along the first direction X, there is a gap between the end of the support member 40 closest to the first wall 12 and the first wall 12 and / or there is a gap between the end of the support member 40 closest to the second electrode assembly 30 and the second inner electrode tab 30a.

[0135] Exemplarily, H / D can be 1, 1.02, 1.05, 1.07, 1.08, 1.1, 1.12, 1.15, 1.18, 1.2, etc.

[0136] In the first direction X, the ratio of the distance between the first wall 12 and the electrode tab of the second electrode assembly 30 closest to the first electrode assembly 20 to the size of the support member 40 is greater than or equal to 1, which facilitates the assembly of the support member 40 between the first electrode assembly 20 and the second wall 13. And if H / D is less than 1, after the assembly is completed, the support member 40 will exert pressure on the second electrode assembly 30. The combined action of the pressure generated during assembly and the pressure during hot pressing can easily cause the electrode tab to bear excessive pressure and break. Therefore, H / D>1 can reduce the risk of the electrode tab breaking due to excessive pressure. In the first direction X, the ratio of the distance between the first wall 12 and the electrode tab of the second electrode assembly 30 closest to the first electrode assembly 20 to the size of the support member 40 is less than or equal to 1.2, so that in the first direction X, the distance between the support member 40 and the electrode tab of the second electrode assembly 30 closest to the first electrode assembly 20 and / or the distance between the support member 40 and the first wall 12 are relatively small. After applying pressure to the secondary battery 100 in the first direction X and the package 10, the first electrode assembly 20, and the second electrode assembly 30 are deformed, the support member 40 can transfer the pressure to the second electrode assembly 30, reducing the risk that the support member 40 cannot transfer the pressure to the second electrode assembly 30. Therefore, 1≤H / D≤1.2 can not only facilitate the assembly of the support member 40 between the first electrode assembly 20 and the second wall 13, reduce the risk of electrode tab damage under pressure, but also enable the support member 40 to effectively transfer pressure between the first wall 12 and the second electrode assembly 30, reduce the risk of black spots, and improve the safety of the secondary battery.

[0137] In some embodiments, 0.1 mm≤H≤6 mm.

[0138] It should be noted that H is only a symbol representing the distance between the first wall 12 and the electrode tab of the second electrode assembly 30 closest to the first electrode assembly 20. It should not be considered that the distances at any position between the first wall 12 and the electrode tab of the second electrode assembly 30 closest to the first electrode assembly 20 are equal. Instead, the distances at any position between the first wall 12 and the electrode tab of the second electrode assembly 30 closest to the first electrode assembly 20 all satisfy 0.1 mm to 6 mm.

[0139] Exemplarily, H can be 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, etc.

[0140] By making the distance between the first wall 12 and the pole piece of the second electrode assembly 30 closest to the first electrode assembly 20 greater than or equal to 0.1 mm along the first direction X, the accommodating cavity 11 of the package 10 for accommodating the first electrode assembly 20 is facilitated for processing and forming. By making the distance between the first wall 12 and the pole piece of the second electrode assembly 30 closest to the first electrode assembly 20 less than or equal to 6 mm along the first direction X, the thickness of the first electrode assembly 20 in the package 10 in the first direction X is smaller, so there can be more space in the package 10 in the first direction X to accommodate the relatively large-sized second electrode assembly 30, which is beneficial to improving the energy density of the secondary battery 100. Therefore, 0.1 mm ≤ H ≤ 6 mm, which facilitates the processing and forming of the accommodating cavity 11 in the package 10 and is beneficial to improving the energy density of the secondary battery 100.

[0141] In some embodiments, 0.1 mm ≤ D ≤ 6 mm.

[0142] Exemplarily, D can be 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, etc.

[0143] By making the size of the support member 40 greater than or equal to 0.1 mm along the first direction X, the size of the support member 40 in the first direction X is larger, which is convenient for manufacturing and forming and is beneficial to effectively transmitting pressure between the first wall 12 and the second electrode assembly 30. By making the size of the support member 40 less than or equal to 6 mm along the first direction X, the space occupied by the support member 40 is reduced, which is beneficial to the secondary battery 100 having a high energy density. Therefore, 0.1 mm ≤ D ≤ 6 mm, which not only facilitates the manufacturing and forming of the package 10, but also enables the secondary battery 100 to have a high energy density.

[0144] As Figures 6 - 8 shown, in some embodiments, along the first direction X, the distance between the pole piece of the second electrode assembly 30 closest to the first electrode assembly 20 and the support member 40 is H 1 , 0 mm ≤ H 1 ≤ 0.5 mm.

[0145] H 1 is the distance between the end of the support member 40 closest to the second inner pole piece 30a and the second inner pole piece 30a along the first direction X.

[0146] As Figure 8 shown, in the embodiment where the insulating member 50 is provided on the surface of the second inner pole piece 30a facing the third wall 14 in the first part 31, H 1 is the distance between the support member 40 and the insulating member 50 in the first direction X. The insulating member 50 can be an insulating coating or adhesive tape.

[0147] Exemplarily, H 1 can be 0 mm, 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, etc.

[0148] By setting the distance between the pole piece closest to the first electrode assembly 20 in the second electrode assembly 30 and the support member 40 to be greater than or equal to 0 mm and less than or equal to 0.5 mm along the first direction X, there is no distance or a small distance between the support member 40 and the pole piece closest to the first electrode assembly 20 in the second electrode assembly 30 in the first direction X. Thus, when the secondary battery 100 is compressed in the first direction X, the support member 40 can act on the second electrode assembly 30, enabling effective pressure transfer between the support member 40 and the second electrode assembly 30, reducing the risk of lithium deposition caused by black spots in the second electrode assembly 30, and improving the safety of the secondary battery 100.

[0149] Such as Figure 6 , Figure 8 As shown, in some embodiments, there is a first gap Q1 between the first negative electrode pole piece 22 and the support member 40 along the second direction Y.

[0150] That is, along the second direction Y, the end of the first negative electrode pole piece 22 closest to the support member 40 does not contact the support member 40, forming a first gap Q1. In embodiments where the first electrode assembly 20 includes multiple first negative electrode pole pieces 22, the end of each first negative electrode pole piece 22 closest to the support member 40 does not contact the support member 40, forming a first gap Q1. The ends of the first negative electrode pole pieces 22 closest to the support member 40 can be flush, and the widths of the first gaps Q1 between the ends of the first negative electrode pole pieces 22 closest to the support member 40 and the support member 40 can be the same. The ends of the first negative electrode pole pieces 22 closest to the support member 40 can be uneven, and the widths of the first gaps Q1 between the ends of the first negative electrode pole pieces 22 closest to the support member 40 and the support member 40 can be different.

[0151] There is a first gap Q1 between the first negative electrode tab 22 and the support member 40 in the second direction Y, reducing the risk of short circuit caused by interference between the support member 40 and the first negative electrode tab 22, and improving the safety of the secondary battery 100. The first gap Q1 also reserves an installation allowance for the installation of the support member 40, facilitating the installation of the support member 40 between the second wall 13 and the first electrode assembly 20, and being able to reduce the risk of short circuit caused by interference between the support member 40 and the first negative electrode tab 22 of the first electrode assembly 20 during and after installation, improving the safety of the secondary battery 100. At the same time, the first gap Q1 also provides an expansion space for the support member 40, reducing the risk of short circuit caused by interference between the support member 40 and the first negative electrode tab 22 after the support member 40 and the first negative electrode tab 22 expand, further improving the safety performance of the secondary battery 100.

[0152] In some embodiments, along the second direction Y, the size of the first gap Q1 is L 1 , 0.1 mm ≤ L 1 ≤ 0.5 mm.

[0153] It should be noted that L 1 is merely a characterization symbol for the size of the first gap Q1 along the second direction Y. It should not be considered that the size of the first gap Q1 along the second direction Y is equal at any position. Instead, the size of the first gap Q1 along the second direction Y satisfies 0.1 mm to 0.5 mm at any position. Among them, the minimum size of the first gap Q1 along the second direction Y is not less than 0.1 mm, and the maximum size of the first gap Q1 along the second direction Y is not greater than 0.5 mm.

[0154] In embodiments where the first electrode assembly 20 includes multiple first negative electrode tabs 22, a first gap Q1 is formed between the end of each first negative electrode tab 22 closest to the support member 40 and the support member 40. The ends of each first negative electrode tab 22 closest to the support member 40 may be flush, and then the widths of the first gaps Q1 between the ends of each first negative electrode tab 22 closest to the support member 40 and the support member 40 may be the same. The ends of each first negative electrode tab 22 closest to the support member 40 may not be flush, and then the widths of the first gaps Q1 between the ends of each first negative electrode tab 22 closest to the support member 40 and the support member 40 may not be the same. The width of each first gap Q1 satisfies 0.1 mm to 0.5 mm.

[0155] Exemplarily, L 1 can be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, etc.

[0156] The dimension of the first gap Q1 along the second direction Y is greater than or equal to 0.1 mm, such that the dimension of the first gap Q1 is relatively large, reducing the risk of short circuit caused by interference between the support member 40 and the first negative electrode tab 22, facilitating the assembly of the support member 40 and providing sufficient space for the expansion of the support member 40, further reducing the risk of interference between the support member 40 and the first negative electrode tab 22, and improving the safety of the secondary battery 100. The dimension of the first gap Q1 along the second direction Y is less than or equal to 0.5 mm, preventing the first gap Q1 from being too large and resulting in a reduction in the energy density of the secondary battery 100. Therefore, 0.1 mm ≤ L 1 ≤ 0.5 mm, which is beneficial to both improving the safety performance of the secondary battery 100 and enhancing the energy density of the secondary battery 100.

[0157] Furthermore, 0.3 mm ≤ L 1 ≤ 0.4 mm.

[0158] L 1 can be 0.3 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, 0.36 mm, 0.37 mm, 0.38 mm, 0.39 mm, 0.4 mm, etc.

[0159] The dimension of the first gap Q1 along the second direction Y is greater than or equal to 0.3 mm, such that the dimension of the first gap Q1 is even larger, further reducing the risk of short circuit caused by interference between the support member 40 and the first negative electrode tab 22, facilitating the assembly of the support member 40 and providing sufficient space for the expansion of the support member 40, further reducing the risk of interference between the support member 40 and the first negative electrode tab 22, and improving the safety of the secondary battery 100. The dimension of the first gap Q1 along the second direction Y is less than or equal to 0.4 mm, preventing the first gap Q1 from being too large and resulting in a reduction in the energy density of the secondary battery 100. Therefore, 0.3 mm ≤ L 1 ≤ 0.4 mm, which is beneficial to further improving the safety performance of the secondary battery 100 and enhancing the energy density of the secondary battery 100.

[0160] The support member 40 and the second wall 13 can be connected to further improve the stability of the support member 40 within the packaging member 10. The support member 40 and the second wall 13 can also not be connected to reduce the assembly difficulty of the secondary battery 100.

[0161] As Figure 6 、 Figure 8 shown, in the embodiment where the support member 40 and the second wall 13 are not connected, there is a second gap Q2 between the support member 40 and the second wall 13 along the second direction Y.

[0162] That is, along the second direction Y, the surface of the support member 40 facing the second wall 13 does not contact the inner surface of the second wall 13, forming the second gap Q2.

[0163] Along the second direction Y, there is a second gap Q2 between the support member 40 and the second wall 13, so that the support member 40 does not contact the second wall 13, which can prevent the generation of frictional force between the second wall 13 and the support member 40 and avoid the problem that the pressure exerted by the support member 40 on the second electrode assembly 30 is blocked.

[0164] Please continue to refer to Figure 6 、 Figure 8 In some embodiments, along the second direction Y, the size of the second gap Q2 is L 2 0mm ≤ L 2 ≤ 0.3mm.

[0165] It should be noted that L2 is only a symbolic representation of the size of the second gap Q2 along the second direction Y. It should not be considered that the size of the second gap along the second direction Y is equal at any position. Instead, the size of the first gap Q1 along the second direction Y satisfies being greater than 0mm and less than or equal to 0.3mm at any position. Among them, the maximum size of the second gap Q2 along the second direction Y is not greater than 0.3mm.

[0166] Exemplarily, L 2 can be 0mm, 0.01mm, 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, etc.

[0167] Since the second gap Q2 between the second wall 13 and the support member 40 in the second direction Y is greater than or equal to 0mm, the support member 40 does not contact the second wall 13. This non-contact solution can prevent the generation of frictional force between the second wall 13 and the support member 40 and avoid the problem that the pressure exerted by the support member 40 on the second electrode assembly 30 is blocked. By making the second gap Q2 between the second wall 13 and the support member 40 in the second direction Y less than or equal to 0.3mm, the gap between the second wall 13 and the support member 40 in the second direction Y is reduced, which is beneficial to improving the energy density of the secondary battery 100. Therefore, 0mm ≤ L 2 ≤ 0.3mm can not only prevent the generation of frictional force between the second wall 13 and the support member 40 from hindering the support member 40 from applying pressure to the second electrode assembly 30, but also be beneficial to improving the energy density of the secondary battery 100.

[0168] As Figure 9 、 Figure 10 shown, in the embodiment where the support member 40 and the second wall 13 are not connected, along the second direction Y, the support member 40 and the second wall 13 may be in contact.

[0169] That is, along the second aspect, the distance between the surface of the support member 40 facing the second wall 13 and the inner surface of the second wall 13 is 0.

[0170] In the second direction Y, the support member 40 contacts the second wall 13, such that the support member 40 has a larger dimension in the second direction Y, which is beneficial to increasing the contact area between the support member 40 and the second electrode assembly 30, thereby reducing the area of the second electrode assembly 30 that is not under pressure, further alleviating the problem of black spots appearing in the region corresponding to the gap between the second electrode assembly 30 and the first electrode assembly 20 and the second wall 13 due to lack of pressure, and being beneficial to improving the cycling performance of the secondary battery 100.

[0171] As Figure 6 , Figure 8 , Figure 10 shown, in some embodiments, along the second direction Y, the distance between the end of the third wall 14 closest to the second wall 13 and the end of the first positive electrode tab 21 closest to the second wall 13 is L 3 , and the dimension of the support member 40 is L 4 , 0.6 ≤ L 4 / L 3 ≤ 0.98.

[0172] Exemplarily, L 4 / L 3 can be 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 0.98, etc.

[0173] By making the ratio of the dimension of the support member 40 and the distance between the end of the third wall 14 closest to the second wall 13 and the end of the first positive electrode tab 21 closest to the second wall 13 along the second direction Y greater than or equal to 0.6, the support member 40 can cover a larger area in the second direction Y, which is beneficial to increasing the contact area between the support member 40 and the second electrode assembly 30, thereby reducing the area of the second electrode assembly 30 that is not under pressure, further alleviating the problem of black spots appearing in the region corresponding to the gap between the second electrode assembly 30 and the first electrode assembly 20 and the second wall 13 due to lack of pressure, and being beneficial to improving the cycling performance of the secondary battery 100.

[0174] By making the ratio of the dimension of the support member 40 and the distance between the end of the third wall 14 closest to the second wall 13 and the end of the first positive electrode tab 21 closest to the second wall 13 along the second direction Y less than or equal to 0.98, it is convenient to install the support member 40 between the second wall 13 and the first electrode assembly 20, and during and after the installation process, the risk of short circuit caused by interference between the support member 40 and the first negative electrode tab 22 of the first electrode assembly 20 can be reduced, improving the safety of the secondary battery 100. At the same time, installation allowance is reserved for the installation of the support member 40 and expansion space is provided for the support member 40, reducing the risk of short circuit caused by interference between the support member 40 and the first negative electrode tab 22 after the support member 40 and the first negative electrode tab 22 expand, further improving the safety performance of the secondary battery 100.

[0175] Therefore, 0.6 ≤ L 4 / L 3 ≤ 0.98, which is beneficial to improving the cycling performance and safety performance of the secondary battery 100.

[0176] In some embodiments, 0.5 mm ≤ L 4 ≤ 5.5 mm.

[0177] Exemplarily, L 3 can be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, etc.

[0178] The dimension of the support member 40 along the second direction Y is greater than or equal to 0.5 mm, such that the dimension of the support member 40 in the second direction Y is relatively large, facilitating manufacturing and forming, and enabling the support member 40 to cover a relatively large area in the second direction Y, which is beneficial to increasing the contact area between the support member 40 and the second electrode assembly 30, thereby reducing the area of the second electrode assembly 30 that is not under pressure, further alleviating the problem of black spots appearing in the region corresponding to the gap between the second electrode assembly 30 and the first electrode assembly 20 and the second wall 13 due to non-pressure, and being beneficial to improving the cycling performance of the secondary battery 100.

[0179] The dimension of the support member 40 along the second direction Y is less than or equal to 5.5 mm, reducing the space occupied by the support member 40, which is beneficial to the secondary battery 100 having a relatively high energy density.

[0180] Therefore, 0.5 mm ≤ L 4 ≤ 5.5 mm, which can reduce the manufacturing and forming difficulty of the support member 40, increase the acting area of the support member 40 on the second electrode assembly 30 in the second direction Y, further alleviate the problem of black spots appearing in the region corresponding to the gap between the second electrode assembly 30 and the first electrode assembly 20 and the second wall 13 due to non-pressure, and is beneficial to improving the energy density of the secondary battery 100.

[0181] In some embodiments, 1 mm ≤ L 3 ≤ 6 mm.

[0182] Exemplarily, L 3 can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, etc.

[0183] Along the second direction Y, the distance between the end of the third wall 14 closest to the second wall 13 and the end of the first positive electrode tab 21 closest to the second wall 13 is greater than or equal to 1 mm, reducing the risk of short circuit of the secondary battery 100 caused by the contact between the first negative electrode tab 22 of the first electrode assembly 20 and the third wall 14, and improving the safety performance of the secondary battery 100. Along the second direction Y, the distance between the end of the third wall 14 closest to the second wall 13 and the end of the first positive electrode tab 21 closest to the second wall 13 is less than or equal to 6 mm, reducing the space in the package 10 that does not accommodate the electrode assembly, which is beneficial to improving the energy density of the secondary battery 100. Therefore, 1 mm ≤ L 3 ≤ 6 mm, which can improve the safety performance and energy density of the secondary battery 100.

[0184] As Figure 11 shown, in some embodiments, along the third direction Z, the size of the support member 40 is not less than the size of the first positive electrode tab 21.

[0185] That is, the size of the support member 40 along the third direction Z is greater than or equal to the size of the first positive electrode tab 21 along the third direction Z.

[0186] By making the size of the support member 40 along the third direction Z not less than the size of the first positive electrode tab 21, the support member 40 covers a larger area in the third direction Z or is conducive to the support member 40 completely covering the non-pressed area of the second electrode assembly 30 in the third direction Z, thereby reducing the non-pressed area of the second electrode assembly 30, and further alleviating the problem of black spots appearing in the area corresponding to the gap between the second electrode assembly 30 and the first electrode assembly 20 and the second wall 13 due to non-pressure, which is beneficial to improving the cycle performance of the secondary battery 100.

[0187] Please continue to refer to Figure 11 , in some embodiments, along the third direction Z, the first positive electrode tab 21 does not extend beyond either end of the support member 40.

[0188] Along the third direction Z, the support member 40 has opposite first and second ends, and the first positive electrode tab 21 has opposite third and fourth ends. The third end is arranged close to the first end, and the fourth end is arranged close to the second end. The first end and the third end can be flush, or the support member 40 extends beyond the third end; the second end and the fourth end can be flush, or the support member 40 extends beyond the fourth end, so that the first positive electrode tab 21 does not extend beyond either end of the support member 40.

[0189] By arranging the first positive electrode tab 21 not to extend beyond either end of the support member 40 along the third direction Z, and the support member 40 completely covering the uncompressed area of the second electrode assembly 30 along the third direction Z, the uncompressed area of the second electrode assembly 30 is reduced, further alleviating the problem of black spots appearing in the area corresponding to the gap between the second electrode assembly 30 and the first electrode assembly 20 and the second wall 13 due to lack of pressure, which is beneficial to improving the cycling performance of the secondary battery 100.

[0190] As Figure 11 shown, in some embodiments, along the third direction Z, the size of the support member 40 is W 1 , 50 mm ≤ W 1 ≤ 100 mm.

[0191] W 1 is the distance between the first end and the second end. Exemplarily, W 1 can be 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 100 mm, etc.

[0192] The size of the support member 40 along the third direction Z is greater than or equal to 50 mm, such that the support member 40 has a relatively large size in the third direction Z, facilitating manufacturing and forming, and enabling the support member 40 to cover a relatively large area in the third direction Z, which is beneficial to increasing the contact area between the support member 40 and the second electrode assembly 30, thereby reducing the uncompressed area of the second electrode assembly 30, further alleviating the problem of black spots appearing in the area corresponding to the gap between the second electrode assembly 30 and the first electrode assembly 20 and the second wall 13 due to lack of pressure, and being beneficial to improving the cycling performance of the secondary battery 100.

[0193] The size of the support member 40 along the third direction Z is less than or equal to 100 mm, reducing the space occupied by the support member 40, which is beneficial for the secondary battery 100 to have a relatively high energy density.

[0194] Therefore, 50 mm ≤ W 1 ≤ 100 mm can reduce the manufacturing and forming difficulty of the support member 40, increase the acting area of the support member 40 on the second electrode assembly 30 in the third direction Z, further alleviate the problem of black spots appearing in the area corresponding to the gap between the second electrode assembly 30 and the first electrode assembly 20 and the second wall 13 due to lack of pressure, and is beneficial to improving the energy density of the secondary battery 100.

[0195] In some embodiments, the material of the support member 40 includes one or more of sodium polyacrylate, polyethylene oxide, polyvinyl alcohol, polypropylene, polyethylene, and polytetrafluoroethylene.

[0196] The support member 40 can be made of any one of sodium acrylate, polyethylene oxide, polyvinyl alcohol, polypropylene, polyethylene, and polytetrafluoroethylene.

[0197] The support member 40 can also be made of at least two of sodium acrylate, polyethylene oxide, polyvinyl alcohol, polypropylene, polyethylene, and polytetrafluoroethylene together.

[0198] Sodium polyacrylate and polyethylene oxide have strong water absorption and water retention properties. The support member 40 made of one or more of sodium polyacrylate and polyethylene oxide can be assembled between the first electrode assembly 20 and the second wall 13 in a non-water-absorbed state. The support member 40 in the non-water-absorbed state is small in volume and light in weight, which is convenient for assembly. After injecting the electrolyte into the package 10, the support member 40 can absorb the electrolyte and serve as a supplement after the subsequent electrolyte is consumed. Polyvinyl alcohol, polypropylene, polyethylene, and polytetrafluoroethylene have good mechanical strength, which is beneficial for the support member 40 to transfer pressure between the first wall 12 and the second electrode assembly 30.

[0199] In some embodiments, the compressive strength of the support member 40 is G, and 20 MPa ≤ G ≤ 40 MPa.

[0200] The compressive strength of the support member 40 is the maximum compressive force that the support member 40 withstands until rupture or yielding in the compression test. The test method is as follows:

[0201] Exemplarily, the compressive strength G of the support member 40 can be 20 MPa, 22 MPa, 25 MPa, 27 MPa, 29 MPa, 30 MPa, 32 MPa, 35 MPa, 40 MPa, etc.

[0202] The compressive strength of the support member 40 being greater than or equal to 20 MPa is beneficial for the support member 40 to transfer pressure between the first wall 12 and the second electrode assembly 30. The compressive strength of the support member 40 being less than or equal to 40 MPa enables the support member 40 to undergo a certain degree of deformation when subjected to pressure along the first direction X, reducing the risk of the electrode sheet of the second electrode assembly 30 being damaged. Therefore, 20 MPa ≤ G ≤ 40 MPa enables the support member 40 to effectively transfer pressure between the first wall 12 and the second electrode assembly 30 and also reduces the risk of the second electrode assembly 30 being damaged.

[0203] In some embodiments, the Young's modulus of the support member 40 is E, and 0.5 GPa ≤ E ≤ 3 GPa.

[0204] Exemplarily, the Young's modulus E of the support member 40 can be 0.5 GPa, 1 GPa, 1.2 GPa, 1.5 GPa, 1.7 GPa, 2 GPa, 2.2 GPa, 2.5 GPa, 2.7 GPa, 3 GPa, etc.

[0205] The Young's modulus of the support member 40 is greater than or equal to 1 GPa, which is beneficial for the support member 40 to transfer pressure between the first wall 12 and the second electrode assembly 30. The Young's modulus of the support member 40 is less than or equal to 3 GPa, so that when the support member 40 is under pressure in the first direction X, it can produce a certain degree of deformation, reducing the risk of the electrode sheet of the second electrode assembly 30 being damaged. Therefore, 0.5 GPa ≤ E ≤ 3 GPa enables the support member 40 to effectively transfer pressure between the first wall 12 and the second electrode assembly 30 and also reduces the risk of the second electrode assembly 30 being damaged.

[0206] The embodiment of the present application also provides an electrical device, which includes the secondary battery 100 provided in any of the above embodiments.

[0207] The secondary battery 100 is used to provide electrical energy for the electrical device.

[0208] The secondary battery 100 provided in any of the above embodiments has good cycle performance, which is beneficial to improving the electrical safety and reliability of the electrical device powered by the secondary battery 100.

[0209] Hereinafter, examples and comparative examples are given to more specifically illustrate the implementation manners of the present application. Various tests and evaluations are carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0210] Test method:

[0211] Test method for the passing rate of black spot test and whether the electrode sheet is damaged:

[0212] The secondary batteries 100 with different H / D and provided with the support member 40 are tested under the condition of 50 °C by the following method to obtain the data in Table 1:

[0213] (1) Stand still for 1 h;

[0214] (2) Constant current discharge at 0.5C to 0% SOC;

[0215] (3) Stand still for 2 min;

[0216] (4) Constant current charge at 1.5C to 80% SOC and constant voltage charge to 1.4C;

[0217] (5) Constant current charge at 0.7C to 100% SOC and constant voltage charge to 0.2C;

[0218] (6) Stand still for 2 min;

[0219] (7) Constant current discharge at 1C to 0% SOC;

[0220] (8) Repeat steps (3) to (7) 200 times;

[0221] (9) Let it stand for 2 min;

[0222] (10) Constant current charge at 1.5C to 80% SOC, and constant voltage charge to 1.4C;

[0223] (11) Constant current charge at 0.7C to 100% SOC, and constant voltage charge to 0.025C;

[0224] (12) Disassemble, and observe whether there are black spots or damages on the electrode sheets in the area of the second electrode assembly 30 corresponding to the gap between the first electrode assembly 20 and the second wall 13.

[0225] Pass rate test method for short - circuit test of secondary battery 100:

[0226] After charging and discharging the secondary battery 100 at 25°C, record the voltage. Drop it freely three times with the step (the first wall 12) facing down by 1 m, and record the voltage after dropping. The voltage drop should be ≤20 mv.

[0227] (1) Let it stand for 10 min;

[0228] (2) Constant current discharge at 0.5C to 0% SOC;

[0229] (3) Let it stand for 10 min;

[0230] (4) Constant current charge at 0.7C to 50% SOC, and constant voltage charge to 0.025C;

[0231] (5) Let it stand for 10 min.

[0232] Test method for Young's modulus of the support member 40:

[0233] Young's modulus refers to the ratio of the tensile stress per unit area to the corresponding unit strain. A material testing machine (model: Shimadzu AGX - V2) can be used. Take a support member with a length of 1 mm and a width of 1 mm, with a tensile speed of 1 mm / min, conduct a tensile test, obtain the curve of tensile stress and strain, and calculate the slope of the straight - line part of the curve to obtain the Young's modulus of the support member.

[0234] The preparation process of the secondary battery provided in Example 1 includes the following steps:

[0235] (1) Preparation of the positive electrode sheet: The active material lithium cobalt oxide (LiCoO 2) Super P (conductive carbon black), CNT (carbon nanotube), and PVDF (polyvinylidene fluoride) are mixed in a weight ratio of 97.5:0.5:0.5:1.5, and N-methylpyrrolidone (NMP) is added as a solvent to formulate a cathode active material with a solid content of 75 wt%. Stir well and set aside. Aluminum foil with a thickness of 10 μm is used as the cathode current collector. The above active material is evenly coated on one side of the cathode current collector using a slot coater, and then dried at 90 °C to obtain a cathode electrode with the cathode active material coated on one side. At this time, the thickness of the cathode active material layer is 50 μm. Then, the above coating steps are repeated on the other side of the cathode current collector. Then, the coated cathode electrode is cold-pressed. After cold pressing, the thickness of the cathode active material layer is 35 μm. The area of the cathode current collector not covered by the cathode active material layer is the cathode empty foil area, and the cathode tab is obtained by die-cutting the cathode empty foil area. Among them, the preparation of the first cathode electrode 21 and the second cathode electrode 32 can both be prepared according to this method. It should be noted that multiple cathode electrodes are prepared in this step. For the first electrode assembly 20, only one side of the cathode current collector of the two cathode electrodes is coated with the cathode active material layer to serve as the two outermost electrodes of the first electrode assembly 20; for the second electrode assembly 30, only one side of the cathode current collector of one cathode electrode is coated with the cathode active material layer to serve as the cathode electrode of the second electrode assembly 30 that is farthest from the first electrode assembly 20.

[0236] (2) Preparation of the anode electrode: Artificial graphite as the active material, Super P (conductive carbon black), SBR (styrene-butadiene rubber), and CMC (sodium carboxymethyl cellulose) are mixed in a weight ratio of 97:0.5:1.3:1.2, and deionized water is added as a solvent to formulate an anode active material with a weight percentage of 50 wt%. Stir well and set aside. Copper foil with a thickness of 10 μm is used as the anode current collector. The above anode active material is evenly coated on one side of the anode current collector using a slot coater, and then dried at 110 °C to obtain an anode electrode with the anode active material coated on one side. At this time, the thickness of the anode active material layer is 55 μm. Then, the above steps are repeated on the other side of the anode current collector to obtain an anode electrode with the anode active material coated on both sides. Then, the coated anode electrode is cold-pressed. After cold pressing, the thickness of the anode active material layer is 45 μm. The area of the anode current collector not covered by the anode active material layer is the anode empty foil area, and the anode tab is obtained by die-cutting the anode empty foil area; among them, the preparation of the first anode electrode 22 and the second anode electrode 33 can both be prepared according to this method.

[0237] (3) Preparation of electrolyte: In a dry argon atmosphere, ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed at a mass ratio of EC:EMC:DEC = 30:50:20 to form a basic organic solvent. Then, lithium salt lithium hexafluorophosphate (LiPF4) was added to the basic organic solvent. 6 ) are dissolved and mixed evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0238] (4) Preparation of separator: A 7 μm thick polyethylene porous polymer film was used as the separator. The first separator 23 and the second separator 34 were prepared by referring to the method.

[0239] (5) Preparation of the first electrode assembly 20: alternately stacking the first positive electrode sheet 21, the first separator 23 and the first negative electrode sheet 22 along the first direction X, wherein each layer of the first separator 23 is a single separator;

[0240] (6) Preparation of the second electrode assembly 30: alternately stacking the second positive electrode sheet 32, the second separator 34 and the second negative electrode sheet 33 along the first direction X, wherein each layer of the first separator 23 is a single separator;

[0241] (7) stacking the first electrode assembly 20 and the second electrode assembly 30 along the first direction X; gathering the positive electrode tabs of the first electrode assembly 20 and the second electrode assembly 30 along the first direction X and welding them to form a positive electrode tab bundle, and gathering the negative electrode tabs of the first electrode assembly 20 and the second electrode assembly 30 along the first direction X and welding them to form a negative electrode tab bundle;

[0242] (8) providing a support member 40;

[0243] (9) Assembly of the secondary battery 100:

[0244] a. The first electrode assembly 20 and the second electrode assembly 30 are stacked along the first direction X to form a whole and placed in the package 10;

[0245] b. The support member 40 is disposed corresponding to the second electrode assembly 30 beyond the first portion 31 of the first electrode assembly 20 and the support member 40 is connected to the first wall 12 of the package 10;

[0246] c. Welding and sealing the edge of the package 10;

[0247] d. After the electrolyte injection, packaging, standing, hot pressing and other processes, the secondary battery 100 is manufactured.

[0248] Comparative Example 1-Comparative Example 2

[0249] In Comparative Example 1, no insulating member was provided. In Comparative Example 2, an insulating member was provided, but the insulating member was not provided between the first electrode assembly and the second wall.

[0250] Examples 2 - 36

[0251] Except for adjusting the relevant dimensional parameters of the lithium-ion battery according to Table 1, the rest were the same as in Example 1.

[0252] The relevant parameters and performance tests of Examples 1 to 36 and Comparative Examples 1 to 2 are shown in Table 1:

[0253] Table 1:

[0254]

[0255]

[0256] As can be seen from Table 1:

[0257] (1) From Comparative Example 1 and Comparative Example 2, it can be seen that comparing the case where the secondary battery 100 is provided with the support member 40 but the support member 40 is not provided between the first electrode assembly 20 and the second wall 13 and the case where the secondary battery 100 is not provided with the support member 40, the black spot test rate of the secondary battery 100 is 0, the electrode sheets of the second electrode assembly 30 are not damaged, and the passing rate of the short-circuit test of the secondary battery 100 is almost 100%.

[0258] From Example 1 and Comparative Example 2, it can be seen that when the secondary battery 100 is provided with the support member, the support member 40 is provided between the first electrode assembly 20 and the second wall 13, effectively improving the passing rate of the black spot test of the secondary battery 100. Therefore, providing the support member 40 between the first electrode assembly 20 and the second wall 13 effectively reduces the risk of black spots on the electrode sheets of the secondary battery 100 and improves the safety performance of the secondary battery 100.

[0259] (2) From Examples 1 - 7, it can be seen that when 1 ≤ H / D ≤ 1.2, the passing rates of the electrode sheet damage and the black spot test of the secondary battery 100 are both relatively high, effectively reducing the risks of black spots and electrode sheet damage of the secondary battery 100 and improving the safety of the secondary battery 100.

[0260] (3) From Example 3 and Examples 8 - 14, it can be seen that when 0.1 mm ≤ L 1 ≤ 0.5 mm, the secondary battery 100 has a relatively high passing rate of the black spot test and the short-circuit test. Thus, when 0.1 mm ≤ L 1 ≤ 0.5 mm, the risks of black spots and short circuits of the secondary battery 100 are relatively low, and the safety of the secondary battery 100 is relatively high. In addition, when 0.3 mm ≤ L 1When it is ≤ 0.4 mm, the passing rates of the black spot test and the short - circuit test of the secondary battery 100 are almost 100%, and the safety of the secondary battery 100 is higher.

[0261] (4) It can be seen from Example 3 and Examples 15 - 18 that when 0 ≤ L 2 ≤ 0.3 mm, the secondary battery 100 has a high passing rate of the black spot test, the short - circuit test, and the passing rate of the pole piece damage test. Thus, when 0 mm ≤ L 2 ≤ 0.3 mm, the risks of the secondary battery 100 having black spots and short - circuits are relatively low.

[0262] (5) From Example 3 and Examples 19 - 24, when 0.6 ≤ L 4 / L 3 ≤ 0.98, the passing rates of the black spot test and the short - circuit test of the secondary battery 100 are both relatively high. Thus, the risks of the secondary battery 100 having black spots and short - circuits can be effectively reduced.

[0263] (6) From Example 3 and Examples 25 - 31, as L3 increases, the energy density of the secondary battery 100 gradually decreases. When L 3 ≤ 6 mm, compared with when L 3 is 6.5 mm, the energy density of the secondary battery 100 decreases significantly; when L 3 ≥ 1 mm, compared with when L 3 is 0.5 mm, the passing rate of the short - circuit test of the secondary battery 100 increases significantly. Therefore, when 1 mm ≤ L 3 ≤ 6 mm, the energy density and the passing rate of the short - circuit test of the secondary battery 100 are both relatively high, enabling the secondary battery 100 to have a relatively high energy density and a reduced risk of short - circuit.

[0264] (7) From Example 3 and Examples 32 - 36, when the Young's modulus of the support member 40 is less than or equal to 3 GMPa, compared with when the Young's modulus of the support member 40 is 4 MPa, the passing rate of the pole piece damage test increases significantly; when the Young's modulus of the support member 40 is greater than or equal to 0.5 GPa, the passing rate of the black spot of the secondary battery 100 increases significantly. Therefore, when 0.5 GPa ≤ E ≤ 3 GPa, the passing rates of the pole piece damage test and the black spot test of the secondary battery 100 are both relatively high. Thus, the risks of the secondary battery 100 having pole piece damage and black spots are effectively reduced, and the safety performance of the secondary battery 100 is improved.

[0265] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application.

Claims

1. A secondary battery, characterized in that: The invention comprises a package, a first electrode assembly and a second electrode assembly, wherein the first electrode assembly and the second electrode assembly are stacked in the package along a first direction, the length of the second electrode assembly is greater than the length of the first electrode assembly along a second direction, the second electrode assembly has a first portion extending beyond the first electrode assembly, and the first direction is perpendicular to the second direction; The package comprises a first wall, a second wall and a third wall, wherein the first wall, the second wall and the third wall are located on the same side of the second electrode assembly along the first direction, the first wall is located on the side of the first electrode assembly away from the second electrode assembly along the first direction, the third wall is arranged facing the first portion, the third wall is closer to the first portion than the first wall along the first direction, and the second wall is arranged facing the first electrode assembly along the second direction; Wherein, the secondary battery further includes a support member, at least a portion of which is disposed between the first electrode assembly and the second wall.

2. The secondary battery according to claim 1, characterized in that: Along the first direction, a distance between the first wall and a pole piece in the second electrode assembly that is closest to the first electrode assembly is H, a size of the support member is D, and 1≤H / D≤1.

2.

3. The secondary battery according to claim 2, characterized in that: 0.1mm≤H≤6mm.

4. The secondary battery according to any one of claims 1 to 3, characterized in that: The first wall is connected to the support member.

5. The secondary battery according to any one of claims 1 to 3, characterized in that: Along the first direction, a distance between the pole piece in the second electrode assembly closest to the first electrode assembly and the support member is H1, 0mm≤H1≤0.5mm.

6. The secondary battery according to any one of claims 1 to 3, characterized in that: The packaging component further includes a first arc transition wall, the first wall and the second wall are connected by the first arc transition wall, and the support component is in contact with the inner surface of the first arc transition wall.

7. The secondary battery according to any one of claims 1 to 3, characterized in that: The first electrode assembly includes a first positive electrode sheet and a first negative electrode sheet, the first positive electrode sheet and the first negative electrode sheet are stacked along the first direction, and along the second direction, two ends of the first negative electrode sheet extend beyond two ends of the first positive electrode sheet; Along the second direction, a first gap is defined between the first negative electrode sheet and the support member.

8. The secondary battery according to claim 7, characterized in that: Along the second direction, a size of the first gap is L1, 0.1 mm≤L1≤0.5 mm.

9. The secondary battery according to claim 8, characterized in that: 0.3mm≤L1≤0.4mm.

10. The secondary battery according to any one of claims 1 to 3, characterized in that: Along the second direction, the support member contacts the second wall.

11. The secondary battery according to any one of claims 1 to 3, characterized in that: Along the second direction, a second gap is provided between the support member and the second wall.

12. The secondary battery according to claim 11, characterized in that: Along the second direction, a size of the second gap is L2, 0 mm ≤ L2 ≤ 0.3 mm.

13. The secondary battery according to any one of claims 1 to 12, characterized in that: The packaging piece further comprises a second arc transition wall, and the third wall is connected to the second wall via the second arc transition wall; The first electrode assembly includes a first positive electrode sheet and a first negative electrode sheet, the first positive electrode sheet and the first negative electrode sheet are stacked along the first direction, and along the second direction, the first negative electrode sheet exceeds both ends of the first positive electrode sheet; Along the second direction, the distance between the end of the third wall closest to the second wall and the end of the first positive electrode sheet closest to the second wall is L3, and the size of the support member is L4, 0.6≤L4 / L3≤0.

98.

14. The secondary battery according to claim 13, characterized in that: 1mm≤L3≤6mm.

15. The secondary battery according to any one of claims 1 to 3, characterized in that: The first electrode assembly includes a first positive electrode sheet and a first negative electrode sheet, the first positive electrode sheet and the first negative electrode sheet are stacked along the first direction, and along the third direction, two ends of the first negative electrode sheet extend beyond two ends of the first positive electrode sheet; Along the third direction, the size of the support member is not less than the size of the first positive electrode plate, and the first direction, the second direction and the third direction are perpendicular to each other.

16. The secondary battery according to claim 15, characterized in that: Along the third direction, the first positive electrode sheet does not extend beyond any end of the support member.

17. The secondary battery according to any one of claims 1 to 3, characterized in that: The material of the support member includes one or more of sodium polyacrylate, polyethylene oxide, polyvinyl alcohol, polypropylene, polyethylene, and polytetrafluoroethylene.

18. The secondary battery according to any one of claims 1 to 3, characterized in that: The Young's modulus of the support member is E, 0.5 GPa≤E≤3 GPa.

19. The secondary battery according to any one of claims 1 to 3, characterized in that: The first electrode assembly includes a first positive electrode sheet, a first isolation membrane and a first negative electrode sheet. The first positive electrode sheet and the first negative electrode sheet are stacked along the first direction. Along the second direction, the first negative electrode sheet exceeds both ends of the first positive electrode sheet, and the first isolation membrane exceeds both ends of the first negative electrode sheet. The length of the first isolation membrane exceeding any end of the first negative electrode sheet is L6, 0.15mm≤L6≤2mm.

20. The secondary battery according to any one of claims 1 to 3, characterized in that: The packaging component is a hard shell, and the electrode sheet of the second electrode assembly closest to the first electrode assembly is a negative electrode sheet.

21. An electrical equipment, characterized in that: Comprising the secondary battery according to any one of claims 1-20.

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