Secondary battery and electronic device

Abstract

Disclosed in the present application are a secondary battery and an electronic device. The secondary battery comprises a first housing, a second housing, an insulating sealing member and an electrode assembly. The second housing and the first housing cover each other to form an accommodating cavity, and an insulating gap is formed between the second housing and the first housing. The electrode assembly comprises a plurality of first electrode sheets, a plurality of second electrode sheets and a plurality of first tabs, wherein the plurality of first tabs converge to form a first tab group, and the first tab group is electrically connected to an inner wall of the first housing; and each second electrode sheet comprises a second sub-electrode sheet, the second sub-electrode sheet is located on the outermost side of the electrode assembly in the direction of thickness thereof, the second sub-electrode sheet comprises a second current collector and a second active material layer, the second current collector has a first surface and a second surface opposite each other, the first surface is provided with a bare foil region, the bare foil region is electrically connected to the inner wall of the second housing, and the second active material layer is arranged on the second surface. The present solution reduces the occupation of the volume of the secondary battery, which facilitates the reduction of the overall size of the secondary battery and the improvement of the volumetric energy density of the secondary battery.

Description

Secondary batteries and electronic devices

[0001] This application claims priority to Chinese Patent Application No. 202411958773.0, filed on December 28, 2024, entitled "Secondary Battery and Electronic Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of energy storage technology, and in particular to a secondary battery and electronic device. Background Technology

[0003] In rechargeable batteries, the requirements for energy density are becoming increasingly stringent. In these batteries, the cathode uses a terminal post to indicate polarity. The recessed portion of the terminal post occupies a certain amount of space, resulting in a larger gap between the cathode tab and the casing. Similarly, the protruding portion of the terminal post also reduces the battery's size, leading to energy density loss. Summary of the Invention

[0004] In view of this, it is necessary to provide a secondary battery and electronic device that can reduce the size of the secondary battery and increase its volumetric energy density.

[0005] An embodiment of the first aspect of this application provides a secondary battery, including a first housing, a second housing, an insulating seal, and an electrode assembly. The first and second housings are conductive; the second housing and the first housing are fitted together to form a receiving cavity, with an insulating gap between them. The insulating seal includes a first sealing portion, a second sealing portion, and a third sealing portion. The third sealing portion is connected between the first and second sealing portions. The first sealing portion is wound around and adhered to the outer periphery of the first housing, the second sealing portion is wound around and adhered to the outer periphery of the second housing, and the third sealing portion seals the insulating gap. The electrode assembly is housed in the receiving cavity and includes a plurality of first electrodes, a plurality of second electrodes, and a plurality of first tabs. Each first tab is electrically connected to one of the first electrodes, and the plurality of first tabs are aggregated to form a first tab group, which is electrically connected to the inner wall of the first housing. The plurality of second electrodes are electrically connected to each other, and each second electrode includes a second sub-electrode located on the outermost side of the electrode assembly in the thickness direction. The second sub-electrode includes a second current collector and a second active material layer. The second current collector has opposing first and second surfaces. The first surface is the surface of the second current collector away from the first electrodes. The second active material layer is disposed on the second surface. The first surface has an empty foil area, which is electrically connected to the inner wall of the second shell.

[0006] In the aforementioned secondary battery, insulation between the first and second housings is achieved through the installation of insulating seals, and the receiving cavity is sealed. The first tab assembly enables electrical connection between multiple first electrodes, and the polarity of the first electrodes is output through electrical connection with the inner wall of the first housing. An empty foil area is provided on the first surface of the second sub-electrode, and the polarity of the multiple second electrodes is output through electrical contact between the empty foil area and the second housing. This solution eliminates the need for terminal posts, reducing the volume occupied by the secondary battery, thereby helping to reduce the overall size of the secondary battery and improve its volumetric energy density.

[0007] In at least one embodiment, the first housing includes a first part and a second part, the second part surrounding the edge of the first part and forming a first cavity with the first part; the second housing includes a third part and a fourth part, the fourth part surrounding the edge of the third part and forming a second cavity with the third part; the first cavity and the second cavity communicate to form a receiving cavity; a first sealing part is wrapped around and bonded to the outer periphery of the second part, and a second sealing part is wrapped around and bonded to the outer periphery of the fourth part.

[0008] When sealing the first housing and the second housing with an insulating seal, the insulating seal is wrapped around the outer periphery of the first housing and the second housing, such that the first sealing part is located on the outer periphery of the second part and the second sealing part is located on the outer periphery of the fourth part, thereby achieving a cover connection between the first housing and the second housing and sealing the electrode assembly in the receiving cavity.

[0009] In at least one embodiment, the second part has a first edge and the fourth part has a second edge; along the thickness direction of the secondary battery, the first housing and the second housing are covered by the alignment of the first edge and the second edge; an insulating gap is formed between the first edge and the second edge.

[0010] Compared to the scheme where the first edge and the second edge are staggered, the scheme where the first edge and the second edge are aligned can reduce the overall size after the first shell and the second shell are closed, which is beneficial to reduce the volume of the secondary battery and increase the volumetric energy density of the secondary battery.

[0011] In at least one embodiment, along the thickness direction of the secondary battery, a plurality of first electrode sheets and a plurality of second electrode sheets are stacked to form the main body of the electrode assembly, a first electrode tab group is stacked between the second part and the main body or between the fourth part and the main body, and the first electrode tab group is electrically connected to the second part and insulated from the fourth part.

[0012] The first electrode and the second electrode are stacked, and the stacked arrangement of the first electrode tabs helps to reduce the space occupied by the electrode assembly, thereby allowing for a smaller housing cavity and a smaller secondary battery size. Furthermore, after the first electrode tabs are stacked, they transfer polarity to the first housing through an electrical connection with the second part, thus allowing the polarity to be discharged through the first housing.

[0013] In at least one embodiment, the electrode assembly includes a plurality of second tabs, each second tab being electrically connected to one of the second electrodes, the plurality of second tabs being assembled to form a second tab group, the second tab group being stacked between the second part and the main body or between the fourth part and the main body, and the second tab group being insulated from the second part and the fourth part respectively.

[0014] The arrangement of the second tabs enables electrical connection between multiple second electrodes. The stacked arrangement of the second tabs reduces the space occupied by the second tabs and the overall space occupied by the electrode assembly, thereby improving the volumetric energy density of the secondary battery.

[0015] In at least one embodiment, the secondary battery includes a first adhesive element, which is a conductor, and is bonded between the first surface and the third part.

[0016] On the one hand, the first adhesive component can fix the electrode assembly to the third part of the second housing, making the electrode assembly less prone to shaking relative to the second housing during drop tests, thus improving the drop performance of the secondary battery. On the other hand, the first adhesive component, as a conductor, can improve the electrical connection stability between the second sub-electrode and the second housing.

[0017] In at least one embodiment, the third part has a conductive surface, and the conductive surface is provided with a protrusion, which is electrically connected to the first surface.

[0018] The engagement between the protrusion and the first surface helps to increase the friction between the first surface and the conductive surface, making it less likely for the electrode assembly and the second housing to move relative to each other, thus improving conductivity stability.

[0019] In at least one embodiment, the secondary battery includes a second adhesive member that fills the space between the first surface and the conductive surface, and the second adhesive member is located on the portion of the conductive surface where no protrusion is provided.

[0020] The second adhesive component further improves the electrical conductivity stability between the first surface and the conductive surface. Furthermore, the second adhesive component is located on the portion of the conductive surface without protrusions, which helps to avoid protrusions, allowing the second sub-electrode and the second housing to achieve electrical connection through contact between the protrusions and the first surface.

[0021] In at least one embodiment, the thickness of the insulating seal is H1, satisfying: 0.01mm≤H1≤2mm.

[0022] Excessively thick insulating seals can reduce the volume of the secondary battery, leading to a loss of volumetric energy density; conversely, excessively thin seals can result in insufficient sealing. A thickness of 0.01mm ≤ H1 ≤ 2mm not only ensures the sealing performance of the secondary battery but also reduces the loss of volumetric energy density.

[0023] In at least one embodiment, 0.1mm ≤ H1 ≤ 1mm. This further reduces the energy density loss of the secondary battery while improving its sealing performance.

[0024] In at least one embodiment, the width of the first sealing portion is W1, satisfying: 3mm ≥ W1 ≥ 0.1mm; and / or, the width of the second sealing portion is W2, satisfying: 3mm ≥ W2 ≥ 0.1mm.

[0025] If the width of the first or second sealing part is too narrow, the sealing effect will be poor; if the width of the first or second sealing part is too large, exceeding the dimensions of the first and second housings, it will increase the volume of the secondary battery and affect its volumetric energy density. Within the above range, sufficient bonding area can be ensured between the insulating seal and the first and second housings, thereby improving the sealing performance between the first and second housings, enhancing the long-term sealing effect of the secondary battery, and minimizing the reduction in the volumetric energy density of the secondary battery.

[0026] In at least one embodiment, 1.5mm ≥ W1 ≥ 0.3mm, and / or, 1.5mm ≥ W2 ≥ 0.3mm. This improves the sealing effect between the first and second housings while minimizing the volumetric energy density loss of the secondary battery.

[0027] In at least one embodiment, the first sealing part, the second sealing part, and the third sealing part are integrally disposed.

[0028] The integrated design allows for direct bonding of the insulating sealant to the first and second housings, reducing bonding steps. It also minimizes the formation of seams between the third and second sealing parts and the first sealing part, thus improving the sealing effect of the insulating sealant.

[0029] In at least one embodiment, at least a portion of the third seal is located within the insulation gap.

[0030] On the one hand, the third sealing part can support the first housing and the second housing, which helps to maintain the insulation gap and keep the first housing and the second housing insulated; on the other hand, the third sealing part can also seal the insulation gap to ensure the sealing between the first housing and the second housing.

[0031] In at least one embodiment, the insulating seal is made of at least one of polymer adhesives, thermoplastics, thermosetting plastics, rubber, and composite materials.

[0032] It can enhance the strength of the insulating seal while ensuring its resistance to electrolyte corrosion, thus reducing the risk of secondary battery leakage due to damage to the insulating seal under conditions such as drops.

[0033] An embodiment of the second aspect of this application provides an electronic device including the secondary battery in any of the above embodiments. Attached Figure Description

[0034] Figure 1 is a perspective view of a secondary battery in one embodiment of this application.

[0035] Figure 2 is an exploded view of the secondary battery in Figure 1.

[0036] Figure 3 is a schematic diagram of an electrode assembly in one embodiment of this application.

[0037] Figure 4 is a partial cross-sectional view of a secondary battery in one embodiment of this application, showing the connection relationship between the first tab assembly and the first housing.

[0038] Figure 5 is a partial cross-sectional view of a secondary battery in one embodiment of this application, showing the connection relationship between the second electrode and the second housing.

[0039] Figure 6 is a partial cross-sectional view of an embodiment of this application, showing the connection relationship between the third part and the second sub-electrode.

[0040] Figure 7 is a partial cross-sectional view of an embodiment of this application illustrating the connection relationship between the convex and concave portions.

[0041] Figure 8 is a partial cross-sectional view of an embodiment of this application, showing the positional relationship between the conductive surface and the first surface.

[0042] Figure 9 is a partial cross-sectional view of a secondary battery in one embodiment of this application, showing the connection relationship between the casing and the insulating seal.

[0043] Figure 10 is a schematic diagram of an electronic device in one embodiment of this application.

[0044] Key Component Symbols: 1000, Electronic Device; 100, Secondary Battery; 10, Electrode Assembly; 10a, First Tab Assembly; 10b, Second Tab Assembly; 10c, Main Body; 11, First Electrode; 11b, First Tab; 111, First Current Collector; 1111, Third Surface; 1112, Fourth Surface; 112, First Active Material Layer; 113, First Sub-Electrode; 12, Second Electrode; 12b, Second Tab; 121, Second Current Collector; 1211, First Surface; 1212, Second Surface; 1213, Recess; 122, Second Active Material Layer; 12 3. Second sub-electrode; 13. Diaphragm; 20. Outer shell; 21. First housing; 211. First part; 212. Second part; 2121. First edge; 213. First cavity; 22. Second housing; 221. Third part; 2211. Conductive surface; 2212. Protrusion; 222. Fourth part; 2221. Second edge; 223. Second cavity; 23. Insulation gap; 30. Insulation seal; 31. First sealing part; 32. Second sealing part; 33. Third sealing part; 40. First adhesive; 50. Second adhesive; X, First direction; Y, Second direction.

[0045] The following detailed description, in conjunction with the accompanying drawings, will further illustrate this application. Detailed Implementation

[0046] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0047] In the description of the embodiments of this application, the technical terms "first", "second", etc. are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0048] It should be noted that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative examples and should not constitute any limitation on this application.

[0049] In rechargeable batteries, the requirements for energy density are becoming increasingly stringent. In these batteries, the cathode uses a terminal post to indicate polarity. The recessed portion of the terminal post occupies a certain amount of space, resulting in a larger gap between the cathode tab and the casing. Similarly, the protruding portion of the terminal post also reduces the battery's size, leading to energy density loss.

[0050] The embodiments of this application provide a secondary battery and an electronic device that can reduce the size of the secondary battery and increase its volumetric energy density.

[0051] Embodiments of this application provide a secondary battery, including a first housing, a second housing, an insulating sealant, and an electrode assembly. The first and second housings are conductive. The second housing and the first housing are fitted together to form a receiving cavity, and an insulating gap exists between the second housing and the first housing. The insulating sealant includes a first sealing portion, a second sealing portion, and a third sealing portion. The third sealing portion is connected between the first and second sealing portions. The first sealing portion is wound around and adhered to the outer periphery of the first housing, the second sealing portion is wound around and adhered to the outer periphery of the second housing, and the third sealing portion seals the insulating gap. The electrode assembly is housed in a receiving cavity. The electrode assembly includes multiple first electrodes, multiple second electrodes, and multiple first tabs. Each first tab is electrically connected to one of the first electrodes. The multiple first tabs are assembled to form a first tab group, which is electrically connected to the inner wall of the first housing. The multiple second electrodes are electrically connected to each other. Each second electrode includes a second sub-electrode. The second sub-electrode is located on the outermost side of the electrode assembly in the thickness direction. The second sub-electrode includes a second current collector and a second active material layer. The second current collector has a first surface and a second surface opposite to each other. The first surface is the surface of the second current collector away from the first electrode. The second active material layer is disposed on the second surface. The first surface has an empty foil area, which is electrically connected to the inner wall of the second housing.

[0052] In the aforementioned secondary battery, insulation between the first and second housings is achieved through the installation of insulating seals, and the receiving cavity is sealed. The first tab assembly enables electrical connection between multiple first electrodes, and the polarity of the first electrodes is output through electrical connection with the inner wall of the first housing. An empty foil area is provided on the first surface of the second sub-electrode, and the polarity of the multiple second electrodes is output through electrical contact between the empty foil area and the second housing. This solution eliminates the need for terminal posts, reducing the volume occupied by the secondary battery, thereby helping to reduce the overall size of the secondary battery and improve its volumetric energy density.

[0053] The embodiments of this application will be further described below with reference to the accompanying drawings.

[0054] As shown in Figures 1 to 3, a first embodiment of this application provides a secondary battery 100. The secondary battery 100 includes an electrode assembly 10 and a housing 20. The housing 20 has a receiving cavity, and the electrode assembly 10 is received within the receiving cavity. The electrode assembly 10 includes a first electrode 11, a second electrode 12, and a separator 13. The separator 13 is disposed between the first electrode 11 and the second electrode 12, and the separator 13 is used to isolate the first electrode 11 and the second electrode 12.

[0055] In some embodiments, the housing 20 is a rigid housing, for example, the housing 20 includes a metal housing of at least one selected from steel alloy, aluminum alloy, and copper alloy.

[0056] In some embodiments, the housing 20 is filled with an electrolyte (not shown), the electrolyte components of which include solvents, electrolyte salts and additives.

[0057] In some embodiments, the electrolyte salt includes at least one of an organic lithium salt or an inorganic lithium salt.

[0058] In some embodiments, the first electrode 11 and the second electrode 12 have opposite polarities. For example, the first electrode 11 is an anode electrode and the second electrode 12 is a cathode electrode. Another example is that the first electrode 11 is a cathode electrode and the second electrode 12 is an anode electrode.

[0059] Referring to Figure 3, in some embodiments, the first electrode 11 includes a first current collector 111 and a first active material layer 112. Along the thickness direction of the first electrode 11, the first current collector 111 includes two opposing surfaces, and the first active material layer 112 is disposed on at least one surface of the first current collector 111 along the thickness direction of the first current collector 111. The thickness direction of the first current collector 111 is a first direction X.

[0060] Referring to Figure 3, in some embodiments, the second electrode 12 includes a second current collector 121 and a second active material layer 122. Along the thickness direction of the second electrode 12, the second current collector 121 has two opposing surfaces, and the thickness direction of the second electrode 12 is consistent with the thickness direction of the second current collector 121. The second active material layer 122 is disposed on at least one surface of the second current collector 121. The thickness direction of the second current collector 121 is a first direction X.

[0061] Taking the first electrode 11 as the anode electrode and the second electrode 12 as the cathode electrode as an example, the first current collector 111 and the second current collector 121 can be metal layers. The first current collector 111 can be a metal layer including at least one of copper, nickel, tantalum, titanium, etc., such as copper foil. The second current collector 121 can be a metal layer including at least one of aluminum, nickel, tantalum, titanium, etc., such as aluminum foil.

[0062] Taking the first electrode 11 as the anode electrode and the second electrode 12 as the cathode electrode as an example, the first active material layer 112 is anode-polarized and includes an anode active material, which may include at least one of graphite, hard carbon, soft carbon, silicon, silicon-oxygen materials, and silicon-carbon materials. The second active material layer 122 is cathode-polarized and includes a cathode active material, which may include at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese iron phosphate, or lithium manganese oxide.

[0063] In related technologies, the electrode assembly 10 uses a pole post to lead out the polarity. The pole post includes a part that protrudes inside the outer shell 20 and a part that protrudes outside the outer shell 20. This results in a larger gap between the electrode assembly 10 and the outer shell 20. The protruding part 2212 also occupies the length dimension of the secondary battery 100, resulting in a loss of volumetric energy density.

[0064] Referring to Figures 1 and 4, in some embodiments, the outer casing 20 includes a first casing 21 and a second casing 22, both of which are conductive. The second casing 22 and the first casing 21 cover each other to form a receiving cavity, and an insulating gap 23 exists between the second casing 22 and the first casing 21. The closing direction of the second casing 22 and the first casing 21 is consistent with the thickness direction of the secondary battery 100, i.e., the first direction X.

[0065] Multiple first electrode plates 11 are provided, and the electrode assembly 10 includes multiple first electrode tabs 11b. Each first electrode tab 11b is electrically connected to one of the first electrode plates 11. Multiple first electrode tabs 11b are gathered to form a first electrode tab group 10a. The first electrode tab group 10a is electrically connected to the inner wall of the first housing 21.

[0066] Referring to Figures 3 to 5, multiple second electrode plates 12 are provided, and the multiple second electrode plates 12 are electrically connected to each other. Each second electrode plate 12 includes a second sub-electrode 123, which is located on the outermost side of the electrode assembly 10 in the thickness direction. The second sub-electrode 123 includes a second current collector 121 and a second active material layer 122. The second current collector 121 has opposing first surfaces 1211 and second surfaces 1212, with the first surface 1211 being the surface of the second current collector 121 away from the first electrode plate 11. The second active material layer 122 is disposed on the second surface 1212, and the first surface 1211 has an empty foil area, which is electrically connected to the inner wall of the second housing 22. For example, the second active material layer 122 includes an anode active material, and the second sub-electrode 123 is a single-sided anode electrode plate.

[0067] The first tab group 10a enables electrical connection between multiple first electrode pieces 11, and the first tab group 10a outputs the polarity of the first electrode pieces 11 through electrical connection with the inner wall of the first housing 21. The first surface 1211 of the second sub-electrode 123 has an empty foil area, and the polarity of multiple second electrode pieces 12 is output through electrical contact between the empty foil area and the second housing 22. This solution eliminates the need for electrode posts on the housing 20 and welding fixtures, reducing the volume occupied by the secondary battery 100, thereby helping to reduce the overall size of the secondary battery 100 and improve its volumetric energy density.

[0068] In addition, eliminating the need to consider the sealing problem at the connection between the terminal post and the outer casing 20 simplifies the structure of the secondary battery 100, reduces the risk of leakage, and lowers the cost of the secondary battery 100.

[0069] In some embodiments, a portion of the first surface 1211 of the second current collector 121 is configured as an empty foil area, or all of the first surface 1211 of the second current collector 121 is configured as an empty foil area. Compared to the scheme where only a portion of the area is configured as an empty foil area, the scheme where all of the area is configured as an empty foil area can improve the electrical connection between the first surface 1211 and the second housing 22.

[0070] In some embodiments, the empty foil area is the surface of the second current collector 121 where the second active material layer 122 is not provided, but areas with a small amount of active material that do not affect the electrical connection effect are also within the scope of the empty foil area.

[0071] Referring to Figures 3 and 4, in some embodiments, the first electrode 11 located on the outermost side of the electrode assembly 10 is a first sub-electrode 113. The first sub-electrode 11a and the second sub-electrode 12a are respectively located on the two outermost sides in the thickness direction of the electrode assembly 10. The first sub-electrode 113 includes a first current collector 111 and a first active material layer 112. The first current collector 111 has a third surface 1111 and a fourth surface 1112 facing each other. The third surface 1111 faces the first housing 21. The first active material layer 112 is disposed on the fourth surface 1112 and is not disposed on the third surface 1111. For example, the first active material includes a cathode active material, and the first sub-electrode 113 is a single-sided cathode electrode.

[0072] Referring to Figure 3, in some embodiments, the first current collector 111 of the first electrode 11 located inside the electrode assembly 10 is provided with a first active material layer 112 on both sides; the second current collector 121 of the second electrode 12 located inside the electrode assembly 10 is provided with a second active material layer 122 on both sides. "Inside the electrode assembly 10" refers to the position between the first sub-electrode 113 and the second sub-electrode 123.

[0073] Referring to Figures 1 and 4, in some embodiments, the secondary battery 100 further includes an insulating seal 30, which includes a first sealing part 31, a second sealing part 32 and a third sealing part 33. The third sealing part 33 is connected between the first sealing part 31 and the second sealing part 32. The first sealing part 31 is wrapped around and bonded to the outer periphery of the first housing 21, the second sealing part 32 is wrapped around and bonded to the outer periphery of the second housing 22, and the third sealing part 33 seals the insulating gap 23.

[0074] The insulating seal 30 achieves insulation between the first housing 21 and the second housing 22, and also seals the receiving cavity.

[0075] Referring to Figures 2 and 4, in some embodiments, the first housing 21 includes a first part 211 and a second part 212. The second part 212 surrounds the edge of the first part 211 and forms a first cavity 213 with the first part 211. The second housing 22 includes a third part 221 and a fourth part 222. The fourth part 222 surrounds the edge of the third part 221 and forms a second cavity 223 with the third part 221. The first cavity 213 and the second cavity 223 communicate to form a receiving cavity. A first sealing part 31 is wrapped around and bonded to the outer periphery of the second part 212, and a second sealing part 32 is wrapped around and bonded to the outer periphery of the fourth part 222.

[0076] For example, the first part 211 and the third part 221 are arranged in a flat plate shape and form the top and bottom of the outer casing 20; the second part 212 and the fourth part 222 form the side of the outer casing 20.

[0077] When the insulating seal 30 is used to seal the first housing 21 and the second housing 22, the insulating seal 30 is wrapped around the outer periphery of the first housing 21 and the second housing 22, such that the first sealing part 31 is located on the outer periphery of the second part 212 and the second sealing part 32 is located on the outer periphery of the fourth part 222, thereby realizing the cover connection between the first housing 21 and the second housing 22 and sealing the electrode assembly 10 in the receiving cavity.

[0078] Referring to Figures 2 and 4, in some embodiments, the second part 212 has a first edge 2121, and the fourth part 222 has a second edge 2221. Along the thickness direction of the secondary battery 100, the first housing 21 and the second housing 22 are closed by aligning the first edge 2121 and the second edge 2221. An insulating gap 23 is formed between the first edge 2121 and the second edge 2221. Here, "aligned connection" means that the first edge 2121 and the second edge 2221 are substantially the same in shape and size, allowing for errors when aligning the first edge 2121 and the second edge 2221; where "connection" refers to an indirect connection, for example, the first edge 2121 and the second edge 2221 are connected by an insulating seal 30.

[0079] Compared to the scheme where the first edge 2121 and the second edge 2221 are misaligned, the scheme where the first edge 2121 and the second edge 2221 are aligned can reduce the overall size of the first housing 21 and the second housing 22 after they are closed, thereby helping to reduce the volume of the secondary battery 100 and increase the volumetric energy density of the secondary battery 100.

[0080] Referring to Figure 4, in some embodiments, along the thickness direction of the secondary battery 100, a plurality of first electrode plates 11 and a plurality of second electrode plates 12 are stacked to form the main body 10c of the electrode assembly 10. A first tab group 10a is stacked between the second part 212 and the main body 10c, or between the fourth part 222 and the main body 10c. The first tab group 10a is electrically connected to the second part 212, and insulated from the fourth part 222. For example, the first tab group 10a is directly welded to the inner wall of the second part 212 after stacking. Alternatively, the first tab group 10a can be welded to the inner wall of the second part 212 via an adapter welding metal sheet, which helps to shorten the length of the first tab group 10a and reduce the risk of breakage due to excessive length.

[0081] The first electrode 11 and the second electrode 12 are stacked, and the first tab assembly 10a is also stacked. This arrangement helps to reduce the space occupied by the electrode assembly 10 in the thickness direction of the secondary battery 100, thereby allowing for a smaller housing cavity and reducing the size of the secondary battery 100. Furthermore, after the first tab assembly 10a is stacked, it transfers polarity to the first housing 21 through an electrical connection with the second part 212, thereby allowing the polarity to be discharged through the first housing 21.

[0082] Referring to Figure 5, in some embodiments, the electrode assembly 10 includes a plurality of second tabs 12b, each second tab 12b being electrically connected to one of the second electrode plates 12, and the plurality of second tabs 12b being assembled to form a second tab group 10b. The second tab group 10b is stacked between the second part 212 and the main body part 10c or between the fourth part 222 and the main body part 10c, and the second tab group 10b is insulated from the second part 212 and the fourth part 222, respectively.

[0083] The arrangement of the second tab assembly 10b enables electrical connection between multiple second electrode pieces 12. The second tab assembly 10b is stacked between the side of the outer casing 20 and the main body 10c, thereby reducing the space occupied by the second tab assembly 10b in the thickness direction of the secondary battery 100 and also reducing the overall space occupied by the electrode assembly 10, thus improving the volumetric energy density of the secondary battery 100. The second sub-electrode piece 123 is electrically connected to the second casing 22 through surface contact, reducing the risk of breakage of the second tab 12b due to pulling between the outer casing 20 and the second tab 12b under drop conditions.

[0084] In some embodiments, the first tab group 10a and the second tab group 10b are located on the same side of the electrode assembly 10 along its length, thereby reducing the size occupied by the first tab group 10a and the second tab group 10b in the length direction of the electrode assembly 10, which is beneficial to reducing the volume of the secondary battery 100.

[0085] Referring to Figure 6, in some embodiments, the secondary battery 100 includes a first adhesive 40, which is a conductor and is bonded between the first surface 1211 and the third portion 221. For example, the first adhesive 40 is a conductive adhesive.

[0086] On the one hand, the first adhesive member 40 can fix the electrode assembly 10 to the third part 221 of the second housing 22, so that the electrode assembly 10 is less likely to shake relative to the second housing 22 during drop tests, thereby improving the drop performance of the secondary battery 100. On the other hand, the first adhesive member 40, as a conductor, can improve the electrical connection stability between the second sub-electrode 123 and the second housing 22.

[0087] Referring to Figures 7 and 8, in some embodiments, the third part 221 has a conductive surface 2211, and the conductive surface 2211 is provided with a protrusion 2212, which is electrically connected to the first surface 1211. For example, the protrusion 2212 is a burr structure. Specifically, a burr structure is formed on the conductive surface 2211 using processes such as laser texturing. As shown in Figure 7, under the action of the protrusion 2212, the second current collector 121 deforms to form a recess 1213, so that the protrusion 2212 extends into the recess 1213, realizing the electrical connection between the protrusion 2212 and the recess 1213. Alternatively, as shown in Figure 8, the burr structure pierces into the second current collector 121 from the first surface 1211.

[0088] The engagement between the protrusion 2212 and the first surface 1211 helps to increase the friction between the first surface 1211 and the conductive surface 2211, making it less likely for the electrode assembly 10 and the second housing 22 to move relative to each other, thereby improving conductivity stability.

[0089] Referring to Figure 7 or Figure 8, in some embodiments, the secondary battery 100 includes a second adhesive 50, which fills the space between the first surface 1211 and the conductive surface 2211, and the second adhesive 50 is located on the portion of the conductive surface 2211 where the protrusion 2212 is not provided. For example, the second adhesive 50 is an adhesive layer, and the adhesive layer material can be polypropylene or the like.

[0090] The second adhesive 50 can further improve the conductivity stability between the first surface 1211 and the conductive surface 2211. Furthermore, the second adhesive 50 is located in the part where the protrusion 2212 is not provided, which helps to avoid the protrusion 2212, so that the second sub-electrode 123 and the second housing 22 can be electrically connected through the contact between the protrusion 2212 and the first surface 1211.

[0091] Referring to Figure 9, in some embodiments, the thickness of the insulating seal 30 is H1, satisfying: 0.01mm ≤ H1 ≤ 2mm. The thickness direction of the insulating seal 30 is the second direction Y shown in Figure 9.

[0092] If the insulating seal 30 is too thick, it will occupy the volume of the secondary battery 100, resulting in a loss of volumetric energy density; if it is too thin, it will result in insufficient sealing. When the thickness of 0.01mm≤H1≤2mm is met, not only can the sealing performance of the secondary battery 100 be guaranteed, but the loss of volumetric energy density of the secondary battery 100 can also be reduced.

[0093] In some embodiments, 0.1mm≤H1≤1mm further ensures the sealing performance of the secondary battery 100 and reduces the volumetric energy density loss of the secondary battery 100.

[0094] Referring to Figure 9, in some embodiments, the width of the first sealing portion 31 is W1, satisfying: 3mm ≥ W1 ≥ 0.1mm. As shown in the figure, when the second portion 212 is perpendicular to the first portion 211, the width direction of the first sealing portion 31 is the first direction X shown in the figure. This ensures that the insulating seal 30 and the first housing 21 have sufficient bonding area, thereby improving the sealing performance between the first housing 21 and the second housing 22 and improving the long-term sealing effect of the secondary battery 100.

[0095] In some embodiments, 1.5mm ≥ W1 ≥ 0.3mm can further reduce the energy density loss of the secondary battery 100 while improving the sealing performance of the secondary battery 100.

[0096] Referring to Figure 9, in some embodiments, the width of the second sealing portion 32 is W2, satisfying: 3mm ≥ W2 ≥ 0.1mm. As shown in the figure, when the fourth portion 222 is perpendicular to the third portion 221, the width direction of the second sealing portion 32 is the first direction X shown in the figure. This ensures that the insulating seal 30 and the second housing 22 have sufficient bonding area, thereby improving the sealing performance between the first housing 21 and the second housing 22 and improving the long-term sealing effect of the secondary battery 100.

[0097] In some embodiments, 1.5mm ≥ W2 ≥ 0.3mm can further reduce the energy density loss of the secondary battery 100 while improving the sealing performance of the secondary battery 100.

[0098] In some embodiments, the first sealing part 31, the second sealing part 32, and the third sealing part 33 are integrally formed. This integral formation allows the insulating sealant 30 to be directly bonded to the first housing 21 and the second housing 22, reducing the bonding steps. Furthermore, it reduces the formation of seams between the third sealing part 33 and the second sealing part 32 and the first sealing part 31, thereby improving the sealing effect of the insulating sealant 30.

[0099] Referring to Figure 9, in some embodiments, at least a portion of the third sealing portion 33 is located in the insulating gap 23. For example, the insulating seal 30 is insulating adhesive paper. After the insulating seal 30 is pasted to the first housing 21 and the second housing 22, the insulating seal 30 is melted by high-temperature heating, so that the molten insulating seal 30 flows into the insulating gap 23 to form the third sealing portion 33.

[0100] On the one hand, the third sealing part 33 can support the first housing 21 and the second housing 22, which helps to maintain the insulation gap 23 and keep the first housing 21 and the second housing 22 insulated; on the other hand, the third sealing part 33 can also seal the insulation gap 23 to ensure the sealing between the first housing 21 and the second housing 22.

[0101] In some embodiments, the insulating seal 30 is made of at least one of polymeric adhesives, thermoplastics, thermosetting plastics, rubber, and composite materials. For example, the polymeric adhesive is at least one of epoxy resin, polyurethane, and fluoropolymer adhesives; the thermoplastic includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, and polypropylene; the thermosetting plastic includes phenolic resin; the rubber material includes at least one of fluororubber and silicone rubber; and the composite material is at least one of glass fiber reinforced plastic and carbon fiber composite material.

[0102] The aforementioned materials can enhance the strength of the insulating seal 30 while ensuring its resistance to electrolyte corrosion, thereby reducing the risk of leakage of the secondary battery 100 due to damage to the insulating seal 30 under conditions such as drops.

[0103] Please refer to Figure 10. An embodiment of this application also provides an electronic device 1000, which includes the secondary battery 100 in any of the above embodiments.

[0104] In some embodiments, the electronic device 1000 may be a mobile phone, a laptop computer, a tablet computer, a drone, a power tool, an electric toy, a game console, a video recorder, a portable recorder, a radio, or a smartwatch, etc., which will not be listed here.

[0105] Furthermore, those skilled in the art should recognize that the above embodiments are merely illustrative of this application and are not intended to limit this application. Any appropriate changes and variations made to the above embodiments within the essential spirit and scope of this application fall within the scope of this application's disclosure.

Claims

1. A secondary battery, characterized in that, include: A first housing, wherein the first housing is a conductor; The second housing is a conductor, and the second housing and the first housing cover each other to form a receiving cavity, with an insulating gap between the second housing and the first housing; An insulating sealant, comprising a first sealing portion, a second sealing portion and a third sealing portion, wherein the third sealing portion is connected between the first sealing portion and the second sealing portion, the first sealing portion is wrapped around and adhered to the outer periphery of the first housing, the second sealing portion is wrapped around and adhered to the outer periphery of the second housing, and the third sealing portion seals the insulating gap; An electrode assembly is housed in the receiving cavity. The electrode assembly includes a plurality of first electrodes, a plurality of second electrodes, and a plurality of first tabs. Each first tab is electrically connected to one of the first electrodes. The plurality of first tabs are aggregated to form a first tab group, which is electrically connected to the inner wall of the first housing. The plurality of second electrodes are electrically connected to each other. Each second electrode includes a second sub-electrode located on the outermost side of the electrode assembly in the thickness direction. The second sub-electrode includes a second current collector and a second active material layer. The second current collector has opposing first and second surfaces. The first surface is the surface of the second current collector away from the first electrodes. The second active material layer is disposed on the second surface. The first surface has an empty foil area, which is electrically connected to the inner wall of the second housing.

2. The secondary battery as described in claim 1, characterized in that, The first housing includes a first part and a second part, the second part surrounding the edge of the first part and forming a first cavity with the first part; the second housing includes a third part and a fourth part, the fourth part surrounding the edge of the third part and forming a second cavity with the third part; the first cavity and the second cavity communicate to form a receiving cavity; the first sealing part is wrapped around and adhered to the outer periphery of the second part, and the second sealing part is wrapped around and adhered to the outer periphery of the fourth part.

3. The secondary battery as described in claim 2, characterized in that, The second part has a first edge, and the fourth part has a second edge; along the thickness direction of the secondary battery, the first housing and the second housing are covered by the alignment of the first edge and the second edge; the insulating gap is formed between the first edge and the second edge.

4. The secondary battery as described in claim 2, characterized in that, Along the thickness direction of the secondary battery, a plurality of first electrode sheets and a plurality of second electrode sheets are stacked to form the main body of the electrode assembly. A first electrode tab group is stacked between the second part and the main body or between the fourth part and the main body, and the first electrode tab group is electrically connected to the second part and insulated from the fourth part.

5. The secondary battery as described in claim 4, characterized in that, The electrode assembly includes a plurality of second tabs, each second tab being electrically connected to one of the second electrode plates. The plurality of second tabs are aggregated to form a second tab group. The second tab group is stacked between the second part and the main body or between the fourth part and the main body, and the second tab group is insulated from the second part and the fourth part, respectively.

6. The secondary battery as described in claim 2, characterized in that, The secondary battery includes a first adhesive component, which is a conductor, and is bonded between the first surface and the third part.

7. The secondary battery as described in claim 2, characterized in that, The third part has a conductive surface, and the conductive surface is provided with a protrusion, which is electrically connected to the first surface.

8. The secondary battery as described in claim 7, characterized in that, The secondary battery includes a second adhesive component, which fills the space between the first surface and the conductive surface, and the second adhesive component is located on the portion of the conductive surface where the protrusion is not provided.

9. The secondary battery as described in any one of claims 1 to 8, characterized in that, The thickness of the insulating seal is H1, which satisfies the following condition: 0.01mm≤H1≤2mm.

10. The secondary battery as described in claim 9, characterized in that, 0.1mm≤H1≤1mm.

11. The secondary battery as described in any one of claims 1 to 8, characterized in that, The width of the first sealing part is W1, which satisfies: 3mm ≥ W1 ≥ 0.1mm; And / or, the width of the second sealing part is W2, which satisfies: 3mm ≥ W2 ≥ 0.1mm.

12. The secondary battery as described in claim 11, characterized in that, 1.5mm ≥ W1 ≥ 0.3mm, and / or 1.5mm ≥ W2 ≥ 0.3mm.

13. The secondary battery as described in any one of claims 1 to 8, characterized in that, The first sealing part, the second sealing part, and the third sealing part are integrally formed.

14. The secondary battery as described in any one of claims 1 to 8, characterized in that, At least a portion of the third sealing portion is located within the insulation gap.

15. The secondary battery as described in any one of claims 1 to 8, characterized in that, The insulating seal is made of at least one of the following materials: polymer adhesive, thermoplastic, thermosetting plastic, rubber, and composite material.

16. An electronic device, characterized in that, Includes the secondary battery as described in any one of claims 1 to 15.

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