A single cell and a battery

Abstract

The application provides a single battery and a battery pack, the single battery comprising: a shell and an electrode assembly, the shell comprising a receiving space and an end wall; the electrode assembly is received in the receiving space; the end wall comprises an inner end face facing the electrode assembly; wherein a liquid retaining layer is arranged between the inner end face and the electrode assembly, and the liquid retaining layer is attached to at least a partial region of the inner end face. The application can improve the technical problem of shell corrosion of the single battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a single cell and a battery pack. Background Technology

[0002] In existing technologies, the sealing performance of a single battery cell gradually decreases during storage or long-term use, allowing moisture to enter from the outside and react with the electrolyte to generate highly corrosive hydrofluoric acid. This hydrofluoric acid corrodes the casing, and the resulting metal ions migrate inside the battery cell with the flow of the electrolyte.

[0003] Metal ions migrating inside a single cell can easily deposit to form metal dendrites. The growth of these metal dendrites can puncture the separator, causing a short circuit inside the cell and thus affecting its safety performance and cycle life. Summary of the Invention

[0004] This invention provides a single cell and a battery pack, which can improve the technical problem of easy shell corrosion inside a single cell.

[0005] The present invention provides a single-cell battery, which includes: a housing and an electrode assembly. The housing includes a receiving space and an end wall. The electrode assembly is received within the receiving space. The end wall includes an inner end face facing the electrode assembly. A liquid-retaining layer is disposed between the inner end face and the electrode assembly, and the liquid-retaining layer is attached to at least a portion of the inner end face.

[0006] In one embodiment of the present invention, the housing further includes a sidewall that surrounds and forms a receiving space, wherein one end of the sidewall is integrally connected to an end wall and the other end forms an opening; or, at least one end of the sidewall forms an opening, and the end wall is mounted on the sidewall and covers at least one of the openings.

[0007] In one embodiment of the present invention, the end wall is made of carbon steel, stainless steel, or carbon steel with a nickel-plated layer on the surface.

[0008] In one embodiment of the present invention, the liquid absorption rate of the liquid-retaining layer is a, where a ≥ 5%.

[0009] In one embodiment of the present invention, a ≤ 2000%.

[0010] In one embodiment of the present invention, the liquid loss rate of the liquid-retaining layer is b, where b ≤ 80%.

[0011] In one embodiment of the present invention, a lower insulating member is further provided between the electrode assembly and the end wall, and a liquid-retaining layer is provided between the lower insulating member and the inner end face.

[0012] In one embodiment of the present invention, the liquid-retaining layer is fixed to the inner end face, or a lower insulating member is further provided between the electrode assembly and the end wall, and the liquid-retaining layer is fixed to the surface of the lower insulating member facing the inner end face.

[0013] In one embodiment of the present invention, an adhesive layer is provided between the liquid-retaining layer and the lower insulating member, and the liquid-retaining layer is bonded to the lower insulating member through the adhesive layer.

[0014] In one embodiment of the present invention, the distance between the edge of the liquid-retaining layer and the edge of the lower insulating member is L1, L1≤3.0mm; and / or, the distance between the edge of the liquid-retaining layer and the edge of the adhesive layer is L2, L2≤3.0mm.

[0015] In one embodiment of the present invention, along the thickness direction of the lower insulating member, the projection of the adhesive layer falls completely into the projection of the liquid-retaining layer, and the projection of the liquid-retaining layer falls completely into the projection of the lower insulating member, where 0 < L1 < L2.

[0016] In one embodiment of the present invention, the single cell further includes an electrode post with a mounting hole on its end wall. The lower insulating member includes a first part and a second part. The first part is disposed between the inner end face and the electrode assembly. The second part passes through the first through hole of the liquid-retaining layer and the second through hole of the adhesive layer in sequence and extends into the mounting hole. The electrode post passes through the second part and is electrically connected to the electrode assembly.

[0017] In one embodiment of the present invention, the first part and the second part are separately configured, the liquid-retaining layer is configured in the first part, and the first part is provided with a third through hole; the edge of the third through hole is flush with the edge of the first through hole, or along the radial direction of the first through hole, and the distance between the edge of the third through hole and the edge of the first through hole is less than or equal to 3.0 mm.

[0018] In one embodiment of the present invention, a liquid-retaining layer is disposed in a first part, the thickness of the first part is W1, 0.05mm ≤W1≤5.0mm, and the thickness of the liquid-retaining layer is W3, 0.01 ≤W3≤2.0mm.

[0019] In one embodiment of the present invention, a lower insulating member is further provided between the electrode assembly and the end wall, and the liquid-retaining layer is thermally bonded to the lower insulating member; or, the liquid-retaining layer is thermally bonded to the end wall.

[0020] In one embodiment of the present invention, a transition layer is further provided between the liquid-retaining layer and the lower insulating component, and the transition layer is softened or melted and then solidified in the thermal composite process.

[0021] In one embodiment of the present invention, the material of the liquid-retaining layer is selected from porous inorganic materials, polymer materials, and fiber materials; preferably, it is any one of non-woven fabric, expanding adhesive, and gel.

[0022] In one embodiment of the present invention, the liquid retention layer is made of expanding adhesive, and the expansion rate of the expanding adhesive is c, where 120% ≤ c ≤ 400%.

[0023] In one embodiment of the present invention, a lower insulating member is further provided between the electrode assembly and the end wall, and the liquid-retaining layer is formed on the inner end face by coating or spraying process, or the liquid-retaining layer is formed on the lower insulating member by coating or spraying process.

[0024] In one embodiment of the present invention, the melting point of the liquid-retaining layer is higher than 60°C and the catalytic temperature is lower than -20°C.

[0025] In one embodiment of the present invention, a lower insulating member is further provided between the electrode assembly and the end wall, and the liquid-retaining layer is fixed on the surface of the lower insulating member facing the inner end face. The electrode assembly presses against the lower insulating member so that the liquid-retaining layer adheres to the end wall.

[0026] In one embodiment of the present invention, the bonding area formed between the liquid-retaining layer and the inner end face is S1, the total area of ​​the inner end face is S2, and 5%≤S1 / S2.

[0027] In one embodiment of the present invention, a lower insulating member is further provided between the electrode assembly and the end wall, and the liquid-retaining layer is fixed to the lower insulating member. The porosity of the surface of the liquid-retaining layer facing the inner end face is d, 5%≤d≤60%.

[0028] In one embodiment of the present invention, the single cell further includes an electrode post, the end wall further includes a mounting hole, the liquid-retaining layer is provided with a first through hole, the electrode post passes through the mounting hole and is electrically connected to the electrode assembly through the first through hole; the edge of the first through hole is flush with the edge of the mounting hole.

[0029] In one embodiment of the present invention, the single cell further includes an electrode post, which includes a column portion, a first limiting portion and a second limiting portion; the end wall also includes a mounting hole, the column portion is disposed through the mounting hole, and the end wall is sandwiched between the first limiting portion and the second limiting portion. The first limiting portion is located inside the housing, and the second limiting portion is located outside the housing and is a riveted flange; a liquid-retaining layer is disposed between the first limiting portion and the end wall.

[0030] In one embodiment of the present invention, the housing further includes a sidewall disposed around the end wall. The sidewall includes an inner sidewall located within the receiving space. The inner sidewall is connected to the outer periphery of the inner end face through a transition surface. At least a portion of the transition surface is fitted with a liquid-retaining layer.

[0031] In one embodiment of the present invention, at least a portion of the inner surface is fitted with a liquid-retaining layer.

[0032] The present invention also provides a battery pack, which includes the individual cells in any of the above embodiments.

[0033] The beneficial effects of the present invention are as follows: In the casing of a single battery cell, a liquid-retaining layer is provided between the inner end face of the end wall and the electrode assembly, and the liquid-retaining layer is attached to at least a portion of the inner end face. In this configuration, after the liquid-retaining layer absorbs the electrolyte, it can form a solid-liquid two-phase interface in the area where it is attached to the inner end face, which plays a liquid-sealing role. This prevents water vapor entering the single battery cell from reacting with the electrolyte on the inner end face and corroding the inner end face, thereby improving the safety performance and cycle life of the single battery cell. Attached Figure Description

[0034] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0035] In the attached diagram:

[0036] Figure 1 This is a cross-sectional view of the overall structure of a single battery cell provided in an embodiment of the present invention; Figure 2 for Figure 1 A magnified view of a portion of region A in the middle; Figure 3 This is a schematic diagram of the welding connection between the end wall and the side wall in another embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of an electrode assembly provided in one embodiment of the present invention; Figure 5 for Figure 2 The diagram shown illustrates the structure in which the liquid-retaining layer is disposed between the inner end face and the lower insulating component in the embodiment shown. Figure 6 This is a schematic diagram of a structure in which an adhesive layer is provided between the liquid-retaining layer and the lower insulating component in one embodiment of the present invention; Figure 7 for Figure 6 A magnified view of the location of the intermediate adhesive layer; Figure 8 This is a schematic diagram of the structure in one embodiment of the present invention, showing the liquid-retaining layer disposed on the inner end face; Figure 9 This is a schematic diagram of a structure in which the liquid-retaining layer is disposed on the lower insulating component in one embodiment of the present invention; Figure 10 This is a schematic diagram of a structure in one embodiment of the present invention, in which an adhesive layer is provided between the liquid-retaining layer and the inner end face; Figure 11 This is a schematic diagram of the structure of the liquid-retaining layer disposed on the lower insulating component through an adhesive layer in one embodiment of the present invention; Figure 12This is a schematic diagram of a structure in which no lower insulating member is provided between the electrode assembly and the end face in one embodiment of the present invention; Figure 13 This is a schematic diagram of a structure in one embodiment of the present invention, showing that the outer edge of the liquid-retaining layer extends beyond the outer edge of the lower insulating member; Figure 14 for Figure 11 A magnified view of a portion of region B in the middle; Figure 15 This is a schematic diagram of the structure in one embodiment of the present invention, showing that the outer edge of the adhesive layer extends beyond the outer edge of the liquid-retaining layer; Figure 16 for Figure 15 A magnified view of a portion of region D in the middle; Figure 17 This is a schematic diagram of the mounting structure of the pole on the lower insulating member and the end wall in one embodiment of the present invention; Figure 18 This is a schematic diagram of the mounting structure of the pole on the lower insulating member and the end wall in another embodiment of the present invention; Figure 19 for Figure 18 Enlarged view of a portion of the structure where the lower and middle insulating components are installed in the mounting holes; Figure 20 for Figure 11 A magnified view of a portion of region C in the middle; Figure 21 This is a schematic diagram of a structure in one embodiment of the present invention, showing that the edge of the first through hole extends beyond the edge of the third through hole; Figure 22 This is a schematic diagram of a structure in one embodiment of the present invention, showing that the edge of the second through hole extends beyond the edge of the first through hole; Figure 23 This is a schematic diagram of a structure in which the edge of the first through hole extends beyond the edge of the second through hole when the lower insulating member is an integral piece in one embodiment of the present invention; Figure 24 This is a schematic diagram of a structure in which the edge of the second through hole extends beyond the edge of the first through hole when the lower insulating member is an integral piece in one embodiment of the present invention; Figure 25 This is a schematic diagram of a structure in which a transition layer is provided between the lower insulating component and the liquid-retaining layer in one embodiment of the present invention; Figure 26 This is a schematic diagram of a structure in which a liquid-retaining layer is provided on the transition surface of the sidewall in one embodiment of the present invention; Figure 27 This is a schematic diagram of a structure in which a liquid-retaining layer is provided on the inner side surface of the sidewall in one embodiment of the present invention; Figure 28 This is a schematic diagram of the battery pack structure in one embodiment of the present invention; Figure 29 This is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention.

[0037] The attached figures are labeled as follows: 100. Single cell; 10. Casing; 11. Receiving space; 12. End wall; 1201. Mounting hole; 121. Inner end face; 13. Side wall; 131. Inner side face; 14. Opening; 15. Transition surface; 16. End cap; 20. Electrode assembly; 21. Positive electrode; 211. Positive current collector; 212. First coated area; 213. First uncoated area; 22. Separator; 23. Negative electrode; 231. Negative current collector; 232. Second coated area; 233. Second uncoated area; 24. Negative electrode tab; 25. Positive electrode tab; 30. Liquid-retaining layer; 31. First through hole; 40. Lower insulating component; 41. First part; 42. Second part; 421. First insulating part; 422. Second insulating part; 43. Third through hole; 50. Adhesive layer; 51. Second through hole; 60. Terminal post; 61. Post body part; 62. First limiting part; 63. Second limiting part; 70. Transition layer; 80. Sealing component; 90. Upper plastic; 200. Battery pack; 210. Housing; 2101. First housing part; 2102. Second housing part; 300. Electronic device; 310. Working part. Detailed Implementation

[0038] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0039] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0040] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0041] Please see Figures 1 to 29This invention provides a single-cell battery 100 and a battery pack 200. The single-cell battery 100 has a liquid-retaining layer 30 disposed between the inner end face 121 of the end wall 12 of the casing 10 and the electrode assembly 20, and the liquid-retaining layer 30 is attached to at least a portion of the inner end face 121. This arrangement allows the liquid-retaining layer 30 to form a solid-liquid two-phase interface in the area attached to the inner end face 121 after absorbing the electrolyte, thus acting as a liquid seal. This prevents moisture entering the single-cell battery 100 from reacting with the electrolyte on the inner end face 121 and corroding it, thereby improving the safety performance and cycle life of the single-cell battery 100.

[0042] Please see Figure 1 In one embodiment of the single cell battery 100 of the present invention, the single cell battery 100 includes a housing 10 and an electrode assembly 20.

[0043] The housing 10 includes a receiving space 11. The receiving space 11 is used to accommodate the electrode assembly 20, electrolyte, and other components. The housing 10 may be open at one end or open at both ends. The shape of the housing 10 is not limited, for example, it may be cylindrical, cuboid, or polygonal. For example, in this embodiment, the receiving space 11 is an approximately cylindrical structure.

[0044] The shell 10 can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. A rust-proof material, such as metallic nickel, can also be plated on the surface of the shell 10. During the storage of raw materials for the end wall 12, the processing of raw materials into the shell 10, and the transportation and storage of the shell 10 after processing, the corrosion protection of the shell material needs to be considered. The presence of the nickel plating layer can play a protective role in the above processes. However, the nickel layer is easily corroded during battery use.

[0045] During long-term cycling of the single-cell battery 100, corrosion of the nickel plating layer on the inner end face 121 of the end wall 12 leads to the deposition of free nickel ions, forming nickel dendrites that can pierce the separator 22 and cause micro-short circuits, thus compromising the cycle life and safety performance of the single-cell battery 100. Therefore, in this embodiment, when the surface of the end wall 12 is coated with a nickel plating layer, it is of great significance to provide a liquid-retaining layer 30 that adheres to the nickel plating layer between the inner end face 121 of the end wall 12 and the electrode assembly 20. After absorbing the electrolyte, the liquid-retaining layer 30 can form an effective liquid seal in the area where it adheres to the inner end face 121, thereby delaying the corrosion of the nickel plating layer.

[0046] For reference Figure 1 and Figure 2The housing 10 also includes an end wall 12 and a side wall 13 surrounding the end wall 12. The end wall 12 includes an inner end face 121 located within the receiving space 11. The side wall 13 and the end wall 12 together enclose the receiving space 11. The connection between the end wall 12 and the side wall 13 can be achieved in various ways, such as integral stamping, integral casting, or separate welding.

[0047] Electrode assembly 20 is disposed within receiving space 11. Electrode assembly 20 is a component in the single cell 100 where electrochemical reactions occur. Receiving space 11 may contain one or more electrode assemblies 20. Exemplarily, in this embodiment, one electrode assembly 20 is disposed within receiving space 11. Please refer to... Figure 4 The electrode assembly 20 is formed by sequentially stacking or winding electrode sheets and separators 22. Specifically, in this embodiment, the electrode assembly 20 is formed by winding electrode sheets and separators 22. Specifically, the electrode assembly 20 includes a positive electrode sheet 21, a separator 22, and a negative electrode sheet 23 wound around the housing 10 axially.

[0048] Please see Figure 4 The positive electrode 21 includes a positive electrode current collector 211 coated with a positive electrode active material layer. A first coated area 212 coated with the positive electrode active material layer and a first uncoated area 213 uncoated with the positive electrode active material layer are formed on the positive electrode current collector 211. The first coated area 212 and the first uncoated area 213 are arranged along the axial direction of the housing 10. The first uncoated area 213 extends to one end of the single cell 100 in the height direction to the outside of the separator 22 and is bent towards the axis of the housing 10 to form a stacked positive electrode tab 25.

[0049] The negative electrode 23 includes a negative current collector 231 and a negative active material layer coated on the negative current collector 231. A second coated area 232 coated with the negative active material layer and a second uncoated area 233 uncoated with the negative active material layer are formed on the negative current collector 231. The second coated area 232 and the second uncoated area 233 are arranged along the axial direction of the housing 10. The second uncoated area 233 extends to the other end of the single cell 100 in the height direction to the outside of the separator 22 and is bent towards the axis of the housing 10 to form a stacked negative electrode tab 24.

[0050] A separator 22 is disposed between the positive electrode 21 and the negative electrode 23 to isolate the positive and negative active material layers. Taking a lithium-ion single-cell battery 100 as an example, the positive current collector 211 can be made of aluminum, and the positive active material layer includes positive active material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative current collector 231 can be made of copper, and the negative active material layer includes negative active material, which can be carbon or silicon, etc. The substrate material of the separator 22 can be polypropylene (PP) or polyethylene (PE), etc. To protect and insulate the electrode assembly 20, an insulating film can also be wrapped around the electrode assembly 20. The insulating film can be synthesized from PP, PE, polyethylene terephthalate (PET), polyvinyl chloride (PVC), or other polymer materials.

[0051] Please see Figure 2 and Figure 5 A liquid-retaining layer 30 is disposed between the inner end face 121 and the electrode assembly 20, and the liquid-retaining layer 30 is attached to at least a portion of the inner end face 121. Specifically, in one embodiment, the liquid-retaining layer 30 is attached to the entire area of ​​the inner end face 121, that is, the inner end face 121 is completely covered by the liquid-retaining layer 30 without any exposed surface. In another embodiment, the liquid-retaining layer 30 is attached to a portion of the inner end face 121, for example, the central area or the outer peripheral area of ​​the inner end face 121.

[0052] There are several ways to achieve the liquid retention layer 30 being attached to the inner end face 121. For example, the liquid retention layer 30 can be fixedly attached to the inner end face 121 by means of thermal bonding or adhesive bonding. Alternatively, the liquid retention layer 30 can also be pressed against the inner end face 121 by other structural components disposed on the side opposite to the inner end face 121.

[0053] The specific material of the electrolyte retention layer 30 is not limited; it can be a porous inorganic material, a polymer material, or a fiber material. Specifically, the electrolyte retention layer 30 can be any of the fiber materials such as cotton, linen, woven fabric, or non-woven fabric, and can be fixed to the lower insulating component 40 by thermal bonding or adhesive layer. The electrolyte retention layer 30 can also be a polymer material such as resin, gel, expanding adhesive, polyolefin film, or superabsorbent resin (e.g., SAP superabsorbent resin / sodium polyacrylate / polyacrylamide superabsorbent resin). The electrolyte retention layer 30 can also be made of ceramic powder, which can be fixed to the end wall 12 or the lower insulating component 40 by spraying. These materials also prevent the generation of gas or impurities due to reaction with the electrolyte, or prevent electrolyte degradation, thereby helping to ensure the stability of the charge and discharge performance of the single cell 100.

[0054] In this embodiment, by providing a liquid-retaining layer 30 between the inner end face 121 and the electrode assembly 20, and attaching the liquid-retaining layer 30 to at least a portion of the inner end face 121, the liquid-retaining layer 30, after absorbing the electrolyte, can form a solid-liquid two-phase interface in the area where it is attached to the inner end face 121, thus playing a liquid-sealing role. This prevents water vapor entering the cell 100 from reacting with the electrolyte on the inner end face 121 and corroding the inner end face 121, thereby improving the safety performance and cycle life of the cell 100.

[0055] Please see Figure 1 and Figure 2 In one embodiment of the present invention, one end of the sidewall 13 is integrally connected to the endwall 12, and the integral connection method includes, but is not limited to, integral stamping. The other end of the sidewall 13 forms an opening 14. An end cap 16 may be provided at the opening 14, and the end cap 16 seals and covers the opening 14.

[0056] In this embodiment, the end wall 12 and the side wall 13 are integrally molded. Since integral molding avoids welding or sealing deformation that may occur during subsequent connection and assembly of the end wall 12 and the side wall 13, it better ensures the initial flatness of the inner end face 121. The flat inner end face 121 provides a good adhesion base for the liquid-retaining layer 30, allowing the liquid-retaining layer 30 to adhere tightly to the inner end face 121, thereby improving the adhesion effect and reducing the risk of adhesion failure during use.

[0057] Please see Figure 3 In one embodiment of the present invention, at least one end of the sidewall 13 forms an opening 14, and an end wall 12 is mounted on the sidewall 13 and covers at least one opening 14. The end wall 12 can be mounted on the sidewall 13 by welding, mechanical sealing, etc. Exemplarily, in this embodiment, the end wall 12 is welded to the sidewall 13.

[0058] Specifically, in one embodiment, an end wall 12 is provided, which covers any one of the openings 14, and the other opening 14 serves as an assembly port or cooperates with other structures (such as end cap 16).

[0059] In another embodiment, two end walls 12 are provided, each correspondingly covering one of the two openings 14. This allows for the provision of a liquid-retaining layer 30 on the inner end faces 121 of both end walls 12 at both ends of the housing 10, achieving a double-sided arrangement of the liquid-retaining layer 30 relative to the electrode assembly 20. By providing the liquid-retaining layer 30 on both sides, the generation of byproducts at both ends of the housing 10 can be suppressed, thereby contributing to further improvement in the safety performance and cycle life of the single-cell battery 100.

[0060] A sealing element 80 can also be provided between the terminal 60 and the end wall 12. The sealing element 80 is compressed and deformed to produce a sealing effect. However, during the long-term use of the single cell 100, a small amount of water vapor will still enter the interior of the single cell 100 from the outside. Therefore, the end wall 12 on which the terminal 40 is installed is more likely to be corroded. By providing a liquid-retaining layer 30 at the inner end face 121 of the end wall 12, an effective liquid seal can be formed, which can avoid or slow down the corrosion of the end wall 12.

[0061] The material of the end wall 12 can be selected according to the electrochemical system, cost requirements, and corrosion resistance requirements of the single cell 100. Optionally, in one embodiment of the present invention, the material of the end wall 12 is carbon steel, stainless steel, or carbon steel with a nickel-plated layer on the surface.

[0062] In one embodiment, the end wall 12 is made of carbon steel. Carbon steel has the advantages of low cost and high mechanical strength.

[0063] In another embodiment, the end wall 12 is made of stainless steel, such as 304 or 316L.

[0064] During the long-term use of the single cell 100, the liquid-retaining layer 30 may be subjected to mechanical forces such as compression. If it does not have sufficient liquid absorption and retention capacity, it is very likely that the protection will fail due to lack of liquid during long-term use. In one embodiment of the present invention, the liquid absorption rate of the liquid-retaining layer 30 is a, where a ≥ 5%.

[0065] It should be noted that the liquid absorption rate 'a' of the liquid-retaining layer 30 can be obtained through various testing methods. For example, in one embodiment, the method for obtaining the liquid absorption rate of the liquid-retaining layer 30 is as follows: First, take a dry sample of the liquid-retaining layer (e.g., nonwoven fabric). Weigh the initial weight of the nonwoven fabric and record it as M0. Next, completely immerse the sample in the electrolyte and let it stand at 25±2℃ for 1 hour to allow it to fully absorb the electrolyte until saturation. Then, remove the sample, suspend it (at room temperature) for 30 seconds, and weigh it, recording it as M1. Calculate the liquid absorption rate a using the following formula: a = (M1 - M0) / M0 × 100%.

[0066] In this embodiment, by controlling the liquid absorption rate of the liquid-retaining layer 30 to be above 5%, it can be ensured that the liquid-retaining layer 30 adsorbs a sufficient amount of electrolyte. During the long-term use of the single cell 100, the liquid-retaining layer 30 may be subjected to mechanical forces such as compression. The sufficient amount of electrolyte adsorption allows the liquid-retaining layer 30 to maintain a stable liquid seal on the inner end face 121 of the end wall 12 even under pressure, effectively avoiding protection failure caused by insufficient liquid absorption or electrolyte loss of the liquid-retaining layer 30, thereby significantly improving the long-term reliability of the single cell 100.

[0067] Based on the liquid absorption rate of the liquid retention layer 30 being greater than or equal to 5%, further, in one embodiment of the present invention, a ≤ 2000%. If the liquid absorption rate of the liquid retention layer 30 is too high (exceeding 2000%), it will swell significantly after adsorbing the electrolyte, which will generate compressive stress on the inner end face 121 and the adjacent electrode assembly 20. The electrode assembly 20 is prone to thermal runaway after being compressed.

[0068] The liquid retention layer 30 also needs to have a certain liquid retention capacity to prevent the electrolyte from leaking out of the single cell 100 during long-term use, which would lead to protection failure. In one embodiment of the present invention, the liquid loss rate of the liquid retention layer 30 is b, where b ≤ 80%.

[0069] The liquid loss rate b was determined according to the following test method: First, take a dry sample of the liquid retention layer 30 and completely immerse it in the electrolyte. Let it stand at 25±2℃ for 1 hour to allow it to fully absorb the electrolyte until saturation. Weigh the sample after saturation and record it as W0. Then, place the saturated liquid retention layer 30 sample in a sealed container and let it stand at a constant temperature of 55±2℃ for 1 hour. Remove the sample and weigh it (at room temperature), recording it as W1. Calculate the liquid loss rate b using the following formula: b = (W0 - W1) / W0 × 100% Where b is in percentage (%).

[0070] It should be noted that "closed environment" here refers to placing the sample in a sealed container to reduce interference from the external environment and ensure that electrolyte loss is only due to insufficient liquid retention capacity of the liquid retention layer 30.

[0071] In actual use, the single cell 100 may face high-temperature conditions. If the liquid loss rate of the liquid retention layer 30 is too high, the adsorbed electrolyte cannot form a continuous and effective liquid seal on the inner end face 121. In this embodiment, by controlling the liquid loss rate to below 80%, it is ensured that the liquid retention layer 30 can still maintain a stable liquid seal on the inner end face 121 of the end wall 12 under high-temperature environment, and continue to play a protective role.

[0072] Please see Figure 2 and Figure 5 In one embodiment of the present invention, a lower insulating member 40 is further disposed between the electrode assembly 20 and the end wall 12, and a liquid-retaining layer 30 is disposed between the lower insulating member 40 and the inner end face 121. Along the height direction of the housing 10, the end wall 12, the liquid-retaining layer 30 and the lower insulating member 40 are stacked.

[0073] There are various specific embodiments for the liquid-retaining layer 30 between the lower insulating member 40 and the inner end face 121. In one embodiment, the liquid-retaining layer 30 is fixed to the inner end face 121; in another embodiment, the liquid-retaining layer 30 is fixed to the surface of the lower insulating member 40 facing the inner end face 121; in yet another embodiment, a lower insulating member 40 is also provided between the electrode assembly 20 and the end wall 12, with the liquid-retaining layer 30 sandwiched between the lower insulating members 40. The lower insulating member 40 can be made of plastic, and the material can be polypropylene (PP) or perfluoroalkoxy resin (PFA), etc.

[0074] In one embodiment, the liquid-retaining layer 30 is fixed to the inner end face 121, and the lower insulating member 40 is in abutting relationship with the liquid-retaining layer 30. Specifically, the liquid-retaining layer 30 can be fixedly attached to the inner end face 121 of the end wall 12 by means of bonding or thermal bonding, and the lower insulating member 40 is installed on the side of the liquid-retaining layer 30 away from the inner end face 121 and abuts against the surface of the liquid-retaining layer 30.

[0075] In another embodiment, the liquid-retaining layer 30 abuts against the inner end face 121 and is fixed to the lower insulating member 40. Specifically, the liquid-retaining layer 30 can be pre-fixed to the side surface of the lower insulating member 40 facing the inner end face 121 by means of bonding or thermal bonding, forming a "lower insulating member 40-liquid-retaining layer 30" composite component. During assembly, the composite component is placed between the electrode assembly 20 and the end wall 12, and the liquid-retaining layer 30 abuts against the inner end face 121. The specific implementation of the abutment between the liquid-retaining layer 30 and the inner end face 121 is not limited. For example, it can be achieved by applying pressure to the lower insulating member 40 through the electrode assembly 20, which is transmitted to the liquid-retaining layer 30 and the end wall 12, thereby pressing the liquid-retaining layer 30 tightly against the inner end face 121. Alternatively, the clamping force generated by the limiting part of the pole and the end wall 12 can be used to clamp the lower insulating member 40, and this clamping force is transmitted to the liquid-retaining layer 30 and the end wall 12, thereby achieving the contact between the liquid-retaining layer 30 and the inner end face 121.

[0076] In this embodiment, the liquid-retaining layer 30 is disposed between the lower insulating member 40 and the inner end face 121. The lower insulating member 40, acting as an independent support component, provides uniform support force to the liquid-retaining layer 30, ensuring the liquid sealing effect. This prevents the liquid-retaining layer 30 from failing due to excessive compression under localized stress, thus ensuring long-term structural stability and guaranteeing the insulation performance between the electrode assembly 20 and the end wall 12. Furthermore, the functional partitioning allows the lower insulating member 40 and the liquid-retaining layer 30 to each be made of optimal materials. For example, the lower insulating member 40 can be made of high-strength insulating plastic, while the liquid-retaining layer 30 can be made of highly absorbent porous material. This avoids the contradiction that a single material cannot simultaneously achieve multiple properties, facilitating material selection.

[0077] It should be noted that in some other embodiments, such as Figure 12 As shown, the lower insulating member 40 can be made of foam, which can meet the requirements of structural support and has good resistance to electrolyte corrosion. The lower insulating member 40 is disposed between the electrode assembly 20 and the inner end face 121. The electrode assembly 20 presses against the lower insulating member 40 so that the liquid-retaining layer 30 adheres to the end wall 12.

[0078] Please see Figure 5 In one embodiment of the present invention, the liquid-retaining layer 30 is fixed to the inner end face 121 and / or fixed to the surface of the lower insulating member 40 facing the inner end face 121.

[0079] Specifically, in one embodiment, the liquid-retaining layer 30 is only fixed to the inner end face 121, that is, the liquid-retaining layer 30 and the lower insulating member 40 are in an abutting relationship, but there is no fixed connection. For example, the liquid-retaining layer 30 can be a non-woven fabric or polyolefin film fixed to the inner end face 121 by adhesive or thermal bonding, or it can be a ceramic particle liquid-absorbing layer formed on the inner end face 121 by spraying or coating process.

[0080] In this application, when the liquid-retaining layer 30 is connected to the inner end face 121 via the adhesive layer 50, to avoid the adhesive layer 50 affecting the liquid-sealing effect, in one embodiment, the adhesive layer 50 can be constructed as a dispensing array. In another embodiment, the adhesive layer 50 can also be designed to have liquid absorption properties to ensure the liquid-sealing effect of the liquid-retaining layer. The above two embodiments can be used individually or in combination. The "dispensing array" refers to an adhesive structure composed of multiple discrete adhesive dots arranged in a predetermined pattern (such as a grid or matrix). Compared to continuous full-surface adhesive application, this dispensing array can reserve additional gaps or channels between the liquid-retaining layer 30 and the inner end face 121, which facilitates the flow and adsorption of the electrolyte, thereby improving the liquid-sealing effect.

[0081] In another embodiment, the liquid-retaining layer 30 is only fixed to the lower insulating member 40, that is, the liquid-retaining layer 30 and the inner end face 121 are in an abutting relationship, but there is no fixed connection. For example, the liquid-retaining layer 30 can be a non-woven fabric or polyolefin film fixed to the lower insulating member 40 by adhesive or thermal bonding, or it can be a ceramic particle liquid-absorbing layer formed on the lower insulating member 40 by spraying or coating process.

[0082] In other embodiments, the opposite sides of the liquid-retaining layer 30 are fixedly connected to the inner end face 121 and the side surface of the lower insulating member 40 facing the inner end face 121, respectively. That is, the liquid-retaining layer 30 is simultaneously fixed to the inner end face 121 and the lower insulating member 40, so that the end wall 12, the liquid-retaining layer 30 and the lower insulating member 40 form an integral laminated structure. For example, the liquid-retaining layer 30 can be a non-woven fabric or polyolefin film that is connected to the inner end face 121 and the lower insulating member 40 by double-sided adhesive or double-sided thermal bonding, respectively.

[0083] This embodiment improves the convenience of processing and assembly, as well as the structural adaptability for long-term use, by fixing the liquid-retaining layer 30 to the inner end face 121 and / or the surface of the lower insulating component 40 facing the inner end face 121. On one hand, the liquid-retaining layer 30 is mostly a soft material, which is difficult to grasp directly by a robotic arm during processing. Pre-compositing it onto the surface of the end wall 12 or the lower insulating component 40 effectively solves the problem of independent transport and positioning of soft materials, thereby reducing assembly difficulty and facilitating industrial production. On the other hand, when the liquid-retaining layer 30 is composited onto the surface of the end wall 12, even if the end wall 12 deforms during use, the liquid-retaining layer 30 can still maintain a good conformal fit, ensuring long-term stability of corrosion protection and liquid retention effects. When the liquid-retaining layer 30 is composited onto the surface of the lower insulating component 40, the composite process can be further simplified, improving processing efficiency.

[0084] Please see Figure 7 and Figure 11 In one embodiment of the present invention, in order to achieve convenient industrialization and avoid changes in the properties of the liquid-retaining layer 30 caused by processes such as thermal bonding, thereby causing a decrease in its performance, an adhesive layer 50 is provided between the liquid-retaining layer 30 and the lower insulating member 40, and the liquid-retaining layer 30 is bonded to the lower insulating member 40 through the adhesive layer 50.

[0085] In one embodiment, the adhesive layer 50 may be double-sided tape, and the liquid-retaining layer 30 is directly bonded to the surface of the lower insulating member 40 via the double-sided tape.

[0086] In another embodiment, the adhesive layer 50 can also be an adhesive layer coated on the surface of the lower insulating component 40. For example, the adhesive layer 50 can be a pressure-sensitive adhesive layer. The liquid-retaining layer 30 is pre-bonded to the surface of the lower insulating component 40 by pressure-sensitive adhesive, and only slight pressure needs to be applied during assembly to achieve fixation, without the need for heating or curing steps, which is beneficial to improving assembly efficiency. The pressure-sensitive adhesive can be selected from acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives, or silicone pressure-sensitive adhesives. The adhesive layer 50 can also be a hot melt adhesive layer. The hot melt adhesive is heated to a molten state and then applied to the surface of the lower insulating component 40, and then adhered to the liquid-retaining layer 30. After cooling, it is rapidly cured to form an adhesive. The hot melt adhesive can be selected from ethylene-vinyl acetate copolymer (EVA) hot melt adhesive, polyolefin hot melt adhesive, or polyamide hot melt adhesive, etc. The adhesive layer 50 can also be a reactive adhesive layer. After application, the adhesive forms a cross-linked structure through moisture curing, heat curing, or two-component mixing reaction, thereby obtaining higher adhesive strength and media resistance. Reactive adhesives can be selected from polyurethane adhesives and silicone adhesives.

[0087] Of course, in other embodiments, the adhesive layer may also be the dispensing array in the aforementioned embodiments, provided that the bonding strength between the liquid-retaining layer 30 and the lower insulating member 40 is satisfied.

[0088] Please see Figure 10 In one embodiment of the present invention, an adhesive layer 50 is provided between the liquid-retaining layer 30 and the inner end face 121. The liquid-retaining layer 30 is bonded to the inner end face 121 through the adhesive layer 50, and the adhesive layer 50 has liquid absorption properties.

[0089] Specifically, the adhesive layer 50 is made of a material that combines adhesive properties and liquid absorption function. For example, the material of the adhesive layer 50 can be selected from one or more of the following: silicone gel, fluorinated polymer materials (such as polyvinylidene fluoride PVDF), cross-linked sodium polyacrylate liquid-absorbing polymer, acrylate liquid-absorbing polymer, inorganic gel / composite material, and polyvinyl alcohol (PVA). While ensuring a firm bond between the liquid-retaining layer 30 and the inner end face 121, the aforementioned materials also possess liquid-absorbing properties that can adsorb and retain the electrolyte, thereby achieving the liquid-retaining function.

[0090] Please see Figure 18 Based on the liquid-retaining layer 30 being disposed on the lower insulating member 40 via the adhesive layer 50, further, in one embodiment of the present invention, please refer to... Figure 13 , Figure 14 , Figure 15 The distance between the edge of the liquid-retaining layer 30 and the edge of the lower insulating member 40 is L1, where L1 ≤ 3.0 mm; and / or, please refer to Figures 20 to 24The distance between the edge of the liquid-retaining layer 30 and the edge of the adhesive layer 50 is L2, where L2 ≤ 3.0 mm. It should be noted that in the above embodiments, the specific shapes of the liquid-retaining layer 30, the adhesive layer 50, and the lower insulating member 40 are not limited and can be selected according to actual needs. For example, they can be disc-shaped, annular, polygonal, square, or rectangular, etc.

[0091] For example, in this embodiment, the housing 10 has a cylindrical structure. Correspondingly, the liquid-retaining layer 30, the adhesive layer 50, and the lower insulating member 40 are all configured as approximately annular to fit the inner cavity shape of the housing 10. The three components can be coaxial or non-coaxial, depending on the assembly requirements.

[0092] Specifically, in one embodiment, the outer edge of the liquid-retaining layer 30 is flush with the outer edge of the lower insulating member 40 along the radial direction of the end wall 12. It should be noted that, in this embodiment, "flush" specifically means that, in the projection direction perpendicular to the plane containing the inner end face 121, the outer edge of the liquid-retaining layer 30 coincides with or is substantially aligned with the outer edge of the lower insulating member 40.

[0093] In another embodiment, please refer to Figure 13 Along the radial direction of the end wall 12, the outer edge of the liquid-retaining layer 30 extends beyond the outer edge of the lower insulating member 40 by a distance L. 11 , 0 < L 11 ≤ 3.0mm. For example, L 11 It can be 1mm, 2mm, or 3mm, etc. When the outer edge of the liquid-retaining layer 30 extends beyond the lower insulating member 40, the extension distance L 11 Satisfy 0 <L 11 ≤ 3.0mm, which can prevent the liquid retention layer 30 from being too large and causing significant friction with the inner wall of the shell 10, thus avoiding the generation of foreign objects.

[0094] In other embodiments, please refer to Figure 14 Along the radial direction of the end wall 12, the outer edge of the lower insulating member 40 extends beyond the outer edge of the liquid-retaining layer 30 by a distance L. 12 , 0 < L 12 ≤ 3.0mm. For example, L 12 It can be 1mm, 2mm, or 3mm, etc. When the outer edge of the current insulating component 40 extends beyond the liquid-retaining layer 30, the excess distance L 11 Satisfy 0 <L 11 With a thickness of ≤ 3.0mm, the lower insulating component 40 can effectively protect the edge of the liquid-retaining layer 30, preventing the soft liquid-retaining layer 30 from directly contacting the housing 10 and causing scratches, while ensuring that the liquid-retaining layer 30 effectively covers the preset working area.

[0095] In one embodiment, the outer edge of the liquid-retaining layer 30 is flush with the outer edge of the adhesive layer 50. It should be noted that, in this embodiment, "flush" specifically means that, in the projection direction perpendicular to the plane containing the inner end face 121, the outer edge of the liquid-retaining layer 30 coincides with or is substantially aligned with the outer edge of the adhesive layer 50. This avoids the risk of adhesion caused by the exposure of the adhesive layer 50 and the adhesion of the liquid-retaining layer 30 to the cutting tool / other parts during the cutting process.

[0096] In another embodiment, please refer to Figure 14 Along the radial direction of the end wall 12, the outer edge of the liquid-retaining layer 30 extends beyond the outer edge of the adhesive layer 50 by a distance L. 21 , 0 < L 21 ≤ 3.0mm. For example, L 21 It can be 1mm, 2mm or 3mm, etc., which can prevent the adhesive layer 50 from sticking to the tool and other parts during the cutting process of the liquid-retaining layer 30, and improve the smoothness of processing.

[0097] In other embodiments, please refer to Figure 15 Along the radial direction of the end wall 12, the outer edge of the adhesive layer 50 extends beyond the outer edge of the liquid-retaining layer 30 by a distance L. 22 , 0 < L 22 ≤ 2.0mm. For example, L 22 It can be 1mm, 1.5mm or 2mm, etc., to ensure that the outer edge of the adhesive layer 50 extends out of a small range, avoiding the risk of adhesion caused by large-area exposure.

[0098] Please see Figure 14 and Figure 20 In one embodiment of the present invention, along the thickness direction of the lower insulating member 40, the projection of the adhesive layer 50 falls completely into the projection of the liquid-retaining layer 30, and the projection of the liquid-retaining layer 30 falls completely into the projection of the lower insulating member 40, 0 < L1 < L2.

[0099] Specifically, please refer to Figure 14 Along the radial direction of the end wall 12, the outer edge of the lower insulating member 40 extends beyond the outer edge of the liquid-retaining layer 30 by a distance L1, and the outer edge of the liquid-retaining layer 30 extends beyond the outer edge of the adhesive layer 50 by a distance L2, wherein 0 < L1 < L2. Also, please refer to... Figure 20 The inner edge of the lower insulating member 40 extends beyond the inner edge of the liquid-retaining layer 30 by a distance L1, and the inner edge of the liquid-retaining layer 30 extends beyond the inner edge of the adhesive layer 50 by a distance L2, wherein 0 < L1 < L2.

[0100] This design ensures that the adhesive layer 50 is completely covered by the liquid-retaining layer 30, effectively preventing the edges of the adhesive layer 50 from being exposed and preventing the adhesive layer 50 from sticking to other parts or cutting tools during the cutting process of the liquid-retaining layer 30. Simultaneously, this design also ensures that the edges of the liquid-retaining layer 30 do not extend beyond the edge of the lower insulating member 40, thus allowing the lower insulating member 40 to effectively protect the edges of the liquid-retaining layer 30 and prevent the soft liquid-retaining layer 30 from directly contacting the housing 10 and causing scratches.

[0101] Please see Figure 16 and Figure 17 In one embodiment of the present invention, the single cell 100 further includes an electrode post 60, and the end wall 12 is provided with a mounting hole 1201. The lower insulating member 40 includes a first part 41 and a second part 42. The first part 41 is disposed between the inner end face 121 and the electrode assembly 20, and at least a portion of the second part 42 passes through the first through hole 31 of the liquid-retaining layer 30 and the second through hole 51 of the adhesive layer 50 in sequence and extends into the mounting hole 1201. The electrode post 60 passes through the second part 42 and is electrically connected to the electrode assembly 20.

[0102] Specifically, the electrode post 60 includes a post body 61, a first limiting part 62, and a second limiting part 63. The first limiting part 62 and the second limiting part 63 are respectively disposed at both ends of the post body 61 in the height direction, and both extend from the outer periphery of the post body 61 to the outer periphery of the end wall 12 along the radial direction of the mounting hole 1201. The post body 61 passes through the through hole of the mounting second part 42. The end of the post body 61 facing the electrode assembly 20 is connected to the first limiting part 62, that is, the first limiting part 62 is located on the inner side of the end wall 12. The end of the post body 61 away from the electrode assembly 20 is connected to the second limiting part 63, that is, the second limiting part 63 is located on the outer side of the end wall 12. The cross-section of the first limiting part 62 and the second limiting part 63 can be circular, square, prismatic, or other irregular contours that can achieve stable conductivity, etc., and this embodiment does not limit this. Optionally, in order to facilitate the production and processing of the pole post 60, in this embodiment, the outer contour of the first limiting part 62 and the outer contour of the second limiting part 63 are both circular contours coaxially arranged with the pole body part 61.

[0103] On the inner side of the end wall 12, the first portion 41 extends at least partially between the first limiting portion 62 and the end wall 12, so as to be clamped and fixed to the end wall 12 by the first limiting portion 62, thereby achieving an insulated connection between the first limiting portion 62 and the end wall 12. The second portion 42 extends at least partially into the mounting hole 1201, thereby achieving an insulated connection between the column portion 61 and the wall of the mounting hole 1201.

[0104] The specific structural form between the first part 41 and the second part 42 of the lower insulating member 40 is not limited, as long as it can achieve an insulating connection between the pole post 60 and the end wall 12. For example, in one embodiment, such as Figure 18and Figure 19 As shown, the first part 41 and the second part 42 can be configured as an integral structure. The first part 41 is disposed between the electrode assembly 20 and the end wall 12, and the second part 42 protrudes relative to the first part 41 toward the side opposite to the electrode assembly 20, passing through the adhesive layer and the liquid-retaining layer in sequence, and is inserted into the mounting hole 1201.

[0105] In another embodiment, such as Figure 16 and Figure 17 As shown, the first part 41 and the second part 42 are independent separate structures. When a separate structure is used, the two parts can be connected and fixed to each other, or they can be left unconnected with a certain installation gap, or they can be partially overlapped to jointly insulate and isolate the electrode assembly 20 and the end wall 12.

[0106] Specifically, such as Figure 16 and Figure 17 As shown, in one embodiment, the first part 41 and the second part 42 are designed separately. The first part 41 is disposed between the end wall 12 and the electrode assembly 20. The cross-section of the second part 42 is approximately L-shaped, and it includes a first insulating part 421 and a second insulating part 422 connected together. The first insulating part 421 extends into the mounting hole 1201, and the second insulating part 422 is clamped between the first limiting part 62 and the end wall 12. Along the radial direction of the mounting hole 1201, the edge of the first insulating part 421 facing away from the mounting hole 1201 overlaps with the inner edge of the first part 41.

[0107] Please see Figure 2 The single cell 100 may further include an upper plastic 90, which is disposed between the end wall 12 and the second limiting portion 63, and surrounds the outer periphery of the electrode post 60. The upper plastic 90 is used to achieve an insulating connection between the second limiting portion 63 and the end wall 12.

[0108] In this embodiment, the single cell 100 also includes an electrode post 60, and the end wall 12 is provided with a mounting hole 1201. The electrode post 60 passes through the mounting hole 1201 and is electrically connected to the electrode assembly 20. Since the electrode post 60 and the end wall 12 are sealed by a sealing element 80, the sealing performance of the sealing element 80 decreases during long-term use of the single cell 100, which increases the possibility of corrosion on the inner end face 121 of the end wall 12. Based on this, the provision of a liquid-retaining layer 30 on the end wall 12 side where the electrode post 60 is installed is particularly necessary in this embodiment.

[0109] Please see Figure 16 and Figure 17In one embodiment of the present invention, the first part 41 and the second part 42 are separately provided. The first part 41 is provided with a third through hole 43, and the second part 42 is installed in the third through hole 43. The third through hole 43 forms the inner edge of the lower insulating member 40, the first through hole 31 forms the inner edge of the liquid-retaining layer, and the second through hole 51 forms the inner edge of the adhesive layer 50.

[0110] Specifically, in one embodiment, the edge of the third through hole 43 is flush with the edge of the first through hole 31 along the radial direction of the end wall 12. That is, the inner edge of the lower insulating member 40 is flush with the inner edge of the liquid-retaining layer 30. It should be noted that, in this embodiment, "flush" specifically means that, in the projection direction perpendicular to the plane where the inner end face 121 is located, the edge of the third through hole 43 coincides with or is substantially aligned with the edge of the first through hole 31.

[0111] In another embodiment, please refer to Figure 20 Along the radial direction of end wall 12, the edge of the third through hole 43 extends beyond the edge of the first through hole 31, that is, the inner edge of the lower insulating member 40 extends beyond the inner edge of the liquid-retaining layer 30. The extension distance is L. 31 , 0 < L 31 ≤ 3.0mm. For example, L 31 It can be 1mm, 2mm or 3mm, etc.

[0112] In other embodiments, please refer to Figure 21 Along the radial direction of the end wall 12, the edge of the first through hole 31 extends beyond the edge of the third through hole 43, that is, the inner edge of the liquid-retaining layer 30 extends beyond the inner edge of the lower insulating member 40. The extension distance is L. 32 , 0 < L 32 ≤ 3.0mm. For example, L 32 It can be 1mm, 2mm or 3mm, etc.

[0113] This embodiment controls the relative position of the first through-hole 31 of the liquid-retaining layer 30 and the third through-hole 43 of the first part 41 of the lower insulating component 40, keeping the distance between their edges within 3.0 mm. This optimizes the risk of assembly interference between the second part 42 and the first part 41 and the liquid-retaining layer 30 during assembly. When the edge of the third through-hole 43 extends beyond the edge of the first through-hole 31, the excess distance L... 31 Satisfy 0 <L 31 ≤ 3.0mm. This range prevents the first through-hole 31 of the liquid-retaining layer 30 from excessively extending and causing significant scraping or folding against the outer peripheral surface of the second part 42, reducing the probability of the liquid-retaining layer 30 curling or shifting at the first through-hole 31 during the assembly of the second part 42. When the edge of the first through-hole 31 extends beyond the edge of the third through-hole 43, the excess distance L 32 Satisfy 0 <L 32≤ 3.0mm. This range prevents the edge of the first through hole 31 from deviating excessively from the mounting hole 1201, preventing the liquid-retaining layer 30 from losing effective liquid seal protection for the critical area of ​​the inner end face 121 near the mounting hole 1201. When both edges are flush, there is no radial misalignment, which minimizes the risk of assembly scratches and ensures that the liquid-retaining layer 30 forms an effective liquid seal protection in the area surrounding the mounting hole 1201.

[0114] In one embodiment, along the radial direction of the end wall 12, the edge of the first through hole 31 is flush with the edge of the second through hole 51, that is, the inner edge of the liquid-retaining layer 30 is flush with the inner edge of the adhesive layer 50. It should be noted that, in this embodiment, "flush" specifically means that, in the projection direction perpendicular to the plane where the inner end face 121 is located, the edge of the first through hole 31 coincides with or is substantially aligned with the edge of the second through hole 51.

[0115] In another embodiment, please refer to Figure 21 Along the radial direction of the end wall 12, the edge of the first through hole 31 extends beyond the edge of the second through hole 51, that is, the inner edge of the liquid-retaining layer 30 extends beyond the inner edge of the adhesive layer 50. The extension distance is L. 41 , 0 < L 41 ≤ 3.0mm. For example, L 41 It can be 1mm, 2mm or 3mm, etc.

[0116] In other embodiments, please refer to Figure 22 Along the radial direction of the end wall 12, the edge of the second through hole 51 extends beyond the edge of the first through hole 31, that is, the inner edge of the adhesive layer 50 extends beyond the inner edge of the liquid-retaining layer 30 by a distance L. 42 , 0 < L 42 ≤ 2.0mm. For example, L 42 It can be 1mm, 1.5mm or 2mm, etc.

[0117] In this embodiment, by controlling the relative positions of the edges of the first through-hole 31 of the liquid-retaining layer 30 and the second through-hole 51 of the adhesive layer 50, the excess distance is kept within a reasonable range, which optimizes the processability and avoids material adhesion problems caused by exposed edges of the adhesive layer 50. When the edge of the first through-hole 31 exceeds the edge of the second through-hole 51, the excess distance L 41 Satisfying 0 < L 41 ≤ 3.0mm. This range ensures that the edge of the second through-hole 51 of the adhesive layer 50 is completely covered by the liquid-retaining layer 30, preventing the adhesive layer 50 from sticking to the cutting tool or other parts due to exposed edges during the cutting and punching process, thus reducing processing difficulty. When the edge of the second through-hole 51 extends beyond the edge of the first through-hole 31, the excess distance L 42 Satisfying 0 < L 42≤ 2.0mm. This range keeps the excess portion of the adhesive layer 50 to a minimum, allowing sufficient allowance for assembly tolerances while preventing large areas of the adhesive layer from being exposed due to excessive excess, thus reducing the risk of material sticking. When both edges are flush and there is no radial misalignment, and the edge of the adhesive layer 50 is completely covered by the liquid-retaining layer 30, the best anti-sticking effect can be achieved.

[0118] Please see Figure 18 and Figure 19 In one embodiment of the present invention, the first part 41 and the second part 42 are integral parts. For example, the first part 41 and the second part 42 can be formed by integral injection molding. The edge of the first through hole 31 is flush with or extends beyond the edge of the second through hole 51, with an extension distance of L. 41 , 0 < L 41 ≤ 3.0mm; or, the edge of the second through hole 51 extends beyond the edge of the first through hole 31 by a distance L. 42 , 0 < L 42 ≤ 2.0mm.

[0119] Specifically, in one embodiment, along the radial direction of the end wall 12, the edge of the first through hole 31 is flush with the edge of the second through hole 51. That is, the inner edge of the liquid-retaining layer 30 is flush with the inner edge of the adhesive layer 50. It should be noted that, in this embodiment, "flush" specifically means that, in the projection direction perpendicular to the plane where the inner end face 121 is located, the edge of the first through hole 31 coincides with or is substantially aligned with the edge of the second through hole 51.

[0120] In another embodiment, please refer to Figure 23 Along the radial direction of the end wall 12, the edge of the first through hole 31 extends beyond the edge of the second through hole 51, that is, the inner edge of the liquid-retaining layer 30 extends beyond the inner edge of the adhesive layer 50. The extension distance is L. 41 , 0 < L 41 ≤ 3.0mm. For example, L 41 It can be 1mm, 2mm or 3mm, etc.

[0121] In other embodiments, please refer to Figure 24 Along the radial direction of end wall 12, the edge of the second through hole 51 extends beyond the edge of the first through hole 31, that is, the inner edge of the adhesive layer 50 extends beyond the inner edge of the liquid-retaining layer 30. The extension distance is L. 42 , 0 < L 42 ≤ 2.0mm. For example, L 42 It can be 1mm, 1.5mm or 2mm, etc.

[0122] In this embodiment, by controlling the relative position of the edges of the first through hole 31 of the liquid-retaining layer 30 and the second through hole 51 of the adhesive layer 50, the excessive distance is controlled within a reasonable range, which can achieve the beneficial effects described in the above embodiment, and will not be elaborated here.

[0123] Please see Figure 15 In one embodiment of the present invention, the thickness of the first portion 41 of the lower insulating member 40 is W1, 0.05mm≤W1≤5.0mm, for example, W1 can be 0.05mm, 2.5mm or 5mm, etc.

[0124] The thickness of the liquid retention layer 30 is W3, where 0.01 mm ≤ W3 ≤ 30.0 mm. For example, W3 can be 0.01 mm, 15 mm, or 30 mm, etc.

[0125] It should be noted that in this embodiment, an adhesive layer 50 may be provided between the liquid-retaining layer 30 and the lower insulating member 40, or no adhesive layer 50 may be provided.

[0126] This embodiment reasonably limits the thickness of the first portion 41 of the lower insulating member 40 to satisfy 0.05mm ≤ W1 ≤ 5.0mm. Since the first portion 41 and the liquid-retaining layer 30 jointly occupy the limited end space inside the battery, their thicknesses need to be compatible.

[0127] When the thickness W1 of the first part 41 is not less than 0.05 mm, it has sufficient rigidity to effectively support the liquid-retaining layer 30, ensuring that the two can work together to achieve stable insulation support after being combined. Meanwhile, the thickness range of the lower insulating component 40 is related to the thickness variation of the liquid-retaining layer 30: if the liquid-retaining layer 30 uses a spray-applied material (such as ceramic powder), its thickness is typically controlled between 0.01 mm and 0.02 mm; if it uses a foam-like porous material, its initial thickness can be relatively large, but the thickness can be significantly reduced after compression, and the upper limit of the initial thickness can usually be relaxed to 30 mm. Given the limited total height inside the housing 10, the upper limit of the thickness W1 of the first part 41 is set at 5.0 mm, which provides sufficient thickness space for the liquid-retaining layer 30, while avoiding the first part 41 being too thick and encroaching on the arrangement space of the electrode assembly 20, thus improving the energy density of the single cell 100.

[0128] If the thickness W1 of the first part 41 is less than 0.05 mm, the supporting strength is insufficient, making it difficult to reliably support the liquid-retaining layer 30, which may easily lead to deformation of the composite structure during assembly or use. If W1 is greater than 5.0 mm, it will excessively compress the thickness margin of the liquid-retaining layer 30 within the limited total thickness space, affecting its liquid-retaining function or encroaching on the space of the electrode assembly 20. Therefore, controlling the thickness of the first part 41 within the range of 0.05 mm to 5.0 mm can achieve an optimized balance between the thickness distribution of the first part 41 and the liquid-retaining layer 30, ensuring that the two work together to achieve the functions of support, insulation and liquid retention within a limited space, thereby ensuring the stability and functional reliability of the overall battery structure.

[0129] Further, please refer to Figure 15 In one embodiment of the present invention, the thickness of the first portion 41 is W1, where 0.1 mm ≤ W1 ≤ 5.0 mm. For example, W1 can be 0.01 mm, 2.5 mm, or 5.0 mm. The thickness of the adhesive layer 50 is W2, where 0 ≤ W2 ≤ 2.0 mm. For example, W2 can be 0 mm, 1 mm, or 2 mm. It should be noted that when W2 = 0, the liquid-retaining layer 30 can also have adhesive properties. The thickness of the liquid-retaining layer 30 is W3, where 0.01 mm ≤ W3 ≤ 5.0 mm. For example, W3 can be 0.01 mm, 2.5 mm, or 5.0 mm.

[0130] In this embodiment, the thicknesses of the first part 41, the adhesive layer 50, and the liquid-retaining layer 30 are respectively limited to satisfy 0.1mm ≤ W1 ≤ 5.0mm, 0 ≤ W2 ≤ 2.0mm, and 0.01mm ≤ W3 ≤ 5.0mm. Since the three components together occupy the limited height space of the shell 10 on the end wall 12 side, their thicknesses are interrelated and directly affect the compactness of the internal structure of the shell 10.

[0131] In one embodiment of the present invention, the liquid-retaining layer 30 is thermally bonded to the lower insulating member 40; or, the liquid-retaining layer 30 is thermally bonded to the end wall 12.

[0132] Please see Figure 9In one embodiment, the liquid-retaining layer 30 is thermally bonded to the lower insulating member 40, specifically thermally bonded to the surface of the lower insulating member 40 facing the inner end face 121. The thermal bonding method between the liquid-retaining layer 30 and the lower insulating member 40 is not limited. For example, in one embodiment, the liquid-retaining layer 30 can be directly thermally bonded to the lower insulating member 40. Specifically, after stacking the liquid-retaining layer 30 and the lower insulating member 40, heating causes partial melting or softening of the contact interface between the liquid-retaining layer 30 and the lower insulating member 40, followed by cooling to form a strong bond. This method is suitable for scenarios where the materials of the liquid-retaining layer 30 and the lower insulating member 40 have similar melting points or good compatibility. For example, when the liquid-retaining layer 30 is a polyolefin film (such as PP or PE film), it can be directly thermally bonded to the surface of a lower plastic (i.e., the lower insulating member 40) of the same or similar material.

[0133] Please see Figure 25 In another embodiment, a transition layer 70 may be provided between the liquid-retaining layer 30 and the lower insulating component 40. The transition layer 70 softens, melts, and then solidifies during the thermal bonding process. The transition layer 70 may be a hot melt adhesive layer, which is melted by heating to bond the liquid-retaining layer 30 to the surface of the lower insulating component 40. This method is suitable for situations where direct thermal bonding between the liquid-retaining layer 30 and the lower insulating component 40 is difficult, such as when the liquid-retaining layer 30 is non-woven fabric, ceramic fiber paper, or porous foam (such as silicone foam or polyurethane foam). In such cases, a strong connection between the two can be achieved by using a hot melt adhesive layer as an intermediate transition layer 70.

[0134] Please see Figure 8 In another embodiment, the liquid-retaining layer 30 is laminated to the inner end face 121 via thermal bonding. The thermal bonding method between the liquid-retaining layer 30 and the inner end face 121 is not limited. For example, in one embodiment, the liquid-retaining layer 30 can be directly laminated to the inner end face 121 via hot pressing. This method is suitable for scenarios where the material of the liquid-retaining layer 30 and the metal end wall 12 have a certain degree of thermal compatibility. For example, when the liquid-retaining layer 30 is a polyolefin film (such as PP or PE film) or thermoplastic nonwoven fabric, it can be partially fused together with the inner end face 121 by heating and pressurizing.

[0135] The liquid-retaining layer 30 is directly bonded to the lower insulating component 40 or the inner end face 121 by thermal bonding, without the need for an additional adhesive layer 50. This simplifies the molding process between the liquid-retaining layer 30 and the end wall 12 or the lower insulating component 40, and also effectively avoids a series of problems caused by the presence of the adhesive layer 50.

[0136] Please see Figure 25In one embodiment of the present invention, a transition layer 70 is further provided between the liquid-retaining layer 30 and the lower insulating component 40, and the liquid-retaining layer 30 and the lower insulating component 40 achieve thermal bonding through the transition layer 70. Specifically, the transition layer 70 is disposed between the liquid-retaining layer 30 and the lower insulating component 40. After heating and pressurization, the transition layer 70 can melt or soften, and solidify upon cooling to form an adhesive. The material of the transition layer 70 can be selected from one or more of polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyimide (PI), oriented polystyrene (OPS), or thermoplastic polyurethane elastomer (TPU). The above materials have good hot melt bonding properties and form a strong bond after cooling.

[0137] In this embodiment, by introducing a transition layer 70, a reliable connection can be achieved between the liquid-retaining layer 30, which is originally difficult to directly thermally bond, and the lower insulating component 40. When the liquid-retaining layer 30 and the lower insulating component 40 have poor material compatibility, the transition layer 70 can serve as an intermediate bridge to avoid damaging the performance of the substrate and provide greater flexibility in material selection.

[0138] In this embodiment, the edge of the transition layer 70 can be flush with the edge of the liquid-retaining layer 30. Specifically, in this embodiment, "flush" means that, in the projection direction perpendicular to the plane containing the inner end face 121, the edge of the liquid-retaining layer 30 coincides with or is substantially aligned with the edge of the lower insulating member 40. In another embodiment, the edge of the transition layer can be flush with the edge of the lower insulating member 40, that is, in the projection direction perpendicular to the plane containing the inner end face 121, the edge of the transition layer 70 coincides with or is substantially aligned with the edge of the lower insulating member 40.

[0139] In one embodiment of the present invention, the liquid-retaining layer 30 is made of expanding adhesive, and the expansion rate of the expanding adhesive is c, where 120% ≤ c ≤ 400%. In this embodiment, the expansion rate specifically refers to the volume expansion rate of the expanding adhesive in the electrolyte. This expansion rate can be obtained by testing according to the GB / T 18173.3 standard.

[0140] If the expansion rate of the expanding adhesive is too low (below 120%), the expansion adhesive will not expand sufficiently after absorbing the electrolyte, making it difficult to tightly adhere to the inner end face 121 of the end wall 12. When there are microscopic unevenness or assembly tolerances on the inner end face 121, the expanding adhesive cannot effectively fill the interface gap, resulting in the electrolyte not being able to completely wet and adhere to the inner end face 121, thus affecting the liquid sealing effect and liquid retention performance. If the expansion rate of the expanding adhesive is too high (above 400%), the expanding adhesive will expand excessively after absorbing the liquid, which may generate large compressive stress on the electrode assembly 20, causing the electrode assembly 20 to be deformed under pressure or occupy too much internal space, affecting the design capacity design of the single cell 100. In this embodiment, by controlling the expansion rate of the expanding adhesive within the range of 120% to 400%, the expanding adhesive can fully expand after absorbing the liquid to tightly adhere to the inner end face 121, forming an effective interface liquid seal, while avoiding excessive expansion that could compress the internal space of the electrode assembly 20, thus achieving an optimized balance between liquid retention effect and structural stability.

[0141] When the liquid-retaining layer 30 is made of expandable adhesive, before the electrolyte is injected into the single cell 100, the expandable adhesive does not extend to the space between the first limiting portion 62 and the end wall 12 of the electrode post 60. After the electrolyte is injected into the single cell 100, the expandable adhesive absorbs the electrolyte and expands radially, extending to the space between the first limiting portion 62 and the end wall 12. Compared to other solutions that require the liquid-retaining layer 30 to be precisely extended to the first limiting portion 62 or the second limiting portion 63 in advance, this embodiment utilizes the adaptive expansion characteristics of the expandable adhesive to achieve a tight seal of the electrode post 60 in the mounting hole 1201 without precise positioning, thereby simplifying the assembly process while obtaining better sealing effect and structural adaptability.

[0142] In one embodiment of the present invention, the liquid-retaining layer 30 is formed on the inner end face 121 by coating or spraying, or is formed on the side surface of the lower insulating member 40 facing the inner end face 121 by coating or spraying.

[0143] Specifically, in one embodiment, the liquid-retaining layer 30 is formed on the inner end face 121 by a coating or spraying process. In this case, the liquid-retaining layer 30 is formed on the inner end face 121, and the side of the liquid-retaining layer 30 facing away from the inner end face 121 may come into contact with the lower insulating member 40 or other structural members, or it may not come into contact with the lower insulating member 40 or other structural members.

[0144] In another embodiment, the liquid-retaining layer 30 is coated or sprayed onto the side surface of the lower insulating member 40 facing the inner end face 121. In this case, the side of the liquid-retaining layer 30 facing the inner end face 121 abuts against the inner end face 121, that is, the lower insulating member 40 forms an abutment relationship with the inner end face 121 through the liquid-retaining layer 30.

[0145] It should be noted that the liquid-retaining layer 30 can be made of materials with liquid-absorbing properties, such as ceramic particles, silica gel particles, liquid-absorbing polymer microspheres, porous inorganic fillers, etc. These materials, through coating or spraying processes, form a porous structure layer that can effectively adsorb and retain the electrolyte.

[0146] In this embodiment, the liquid-retaining layer 30 is directly formed on the inner end face 121 or the surface of the lower insulating component 40 through a coating or spraying process. This method allows the thickness of the liquid-retaining layer 30 to be controlled within a small range, typically reaching the micrometer level (e.g., ceramic particle coatings can be as thin as about 20 μm), reducing the space occupied inside the housing 10. Furthermore, after curing, it forms a strong and reliable connection, making it less prone to detachment or displacement during the deformation of the end wall 12, which helps ensure the stability of the liquid sealing effect on the inner end face 121.

[0147] In one embodiment of the present invention, the melting point of the liquid-retaining layer 30 is higher than 60°C and the embrittlement temperature is lower than -20°C. Under the low temperature condition of -20°C, the liquid-retaining layer 30 material can still maintain its structural integrity and liquid absorption performance, and will not fail due to embrittlement, shrinkage or cracking.

[0148] In one embodiment of the present invention, a lower insulating member 40 is provided between the electrode assembly 20 and the end wall 12, and a liquid-retaining layer 30 is fixed to the surface of the lower insulating member 40 facing the inner end face 121. The electrode assembly 20 presses against the lower insulating member 40 so that the liquid-retaining layer 30 adheres to the end wall 12.

[0149] Specifically, in one embodiment, the end of the electrode assembly 20 facing the end wall 12 is in direct contact with the surface of the lower insulating member 40 opposite to the liquid-retaining layer 30. The electrode assembly 20 supports the lower insulating member 40 in contact with the end wall 12. In another embodiment, a collector plate is connected to the end of the electrode assembly 20 facing the end wall 12. The collector plate is electrically connected to the electrode assembly 20 and stacked. The surface of the collector plate opposite to the electrode assembly 20 abuts against the lower insulating member 40, uniformly transmitting the supporting force of the electrode assembly 20 to the lower insulating member 40, thereby causing the liquid-retaining layer 30 to adhere to the end wall 12.

[0150] In one embodiment of the present invention, the contact area formed between the liquid-retaining layer 30 and the inner end face 121 is S1, the total area of ​​the inner end face 121 is S2, and 5% ≤ S1 / S2. Specifically, the total area S2 of the inner end face 121 is the overall area of ​​the surface. The liquid-retaining layer 30 is disposed between the inner end face 121 and the lower insulating member 40, and its side surface facing the inner end face 121 abuts against the inner end face 121. The actual contact area of ​​this abutting area is the contact area S1.

[0151] The pore structure on the surface of the liquid-retaining layer 30 facing the inner end face 121 affects the liquid-sealing effect. For example, when the liquid-retaining layer 30 is a non-woven fabric, non-woven fabrics prepared by hydroentangling or needle punching have a more uniform pore distribution and a smoother surface, enabling effective liquid sealing after electrolyte impregnation. However, non-woven fabrics prepared by meltblowing or spunbonding may have certain unevenness defects on the bonding surface, affecting the liquid-sealing effect. Therefore, in practical applications, controlling the surface porosity of the liquid-retaining layer 30 can ensure the liquid-sealing effect after impregnation.

[0152] This embodiment uses the following testing method to obtain the surface porosity of the liquid-retaining layer 30: 1) Place the pressure-sensitive test paper between the inner end face 121 of the liquid-retaining layer 30 and the flat pressure block; 2) Apply a pressure of 0.2 MPa and maintain the pressure for 1 minute; 3) Remove the pressure block and observe the color development area of ​​the pressure-sensitive test paper; 4) Calculate the color development area using image analysis software and calculate the surface porosity according to the following formula: Surface porosity = (Total surface area - Color development area) / Total surface area × 100%. Wherein, the total surface area is the total area of ​​the tested surface of the liquid-retaining layer 30, and the color development area is the color development area left on the pressure-sensitive test paper by the actual contact area under pressure.

[0153] Please see Figure 5 In one embodiment of the present invention, the liquid-retaining layer 30 is fixed to the lower insulating member 40, and the fixing method includes, but is not limited to, adhesive fixing, thermal bonding fixing, etc. The porosity d of the surface of the liquid-retaining layer 30 facing the inner end face 121 is 5%≤d≤60%. For example, d can be 5%, 30%, or 60%, etc.

[0154] It should be noted that, in this embodiment, surface porosity refers to the percentage of the pore area on the surface of the liquid-retaining layer 30 facing the inner end face 121 to the total surface area. Furthermore, the width of a single pore is less than 0.8 mm. Preferably, the pores should be uniformly distributed.

[0155] To test the liquid-sealing capability of the liquid-retaining layer 30, this embodiment also provides a colorimetric dyeing test method: 1) Immerse the liquid-retaining layer 30 in the colorimetric agent for 5 minutes; 2) Remove the liquid-retaining layer 30 and let it stand in the air for 5 minutes to allow the colorimetric agent to stop dripping; 3) Place the liquid-retaining layer 30 with the colorimetric agent adsorbed on colorimetric paper and apply a pressure of 0.2 MPa; 4) Remove the liquid-retaining layer 30 and observe the colored area on the colorimetric paper; 5) Calculate the colored area using image analysis software; 6) Calculate the surface porosity using the same formula as in test method 1. When the liquid-retaining layer 30 is wetted with electrolyte, its surface porosity should be less than 10%.

[0156] In one embodiment of the present invention, the single cell 100 further includes an electrode post 60, and the end wall 12 further includes a mounting hole 1201. The liquid-retaining layer 30 is provided with a first through hole 31. The electrode post 60 passes through the mounting hole 1201 and is electrically connected to the electrode assembly 20 through the first through hole 31. The edge of the first through hole 31 is flush with the edge of the mounting hole 1201. In this embodiment, the specific structure of the electrode post 60 and the specific installation structure of the electrode post 60 in the mounting hole 1201 can be referred to the relevant descriptions in the foregoing embodiments, and will not be repeated here.

[0157] The edge of the first through hole 31 is flush with the edge of the mounting hole 1201. Specifically, the diameter of the first through hole 31 is equal to the diameter of the mounting hole 1201, and the first through hole 31 and the mounting hole 1201 are coaxially arranged.

[0158] In this embodiment, by aligning the edge of the first through hole 31 with the edge of the mounting hole 1201, and considering that the electrode 60 and the end wall 12 are sealed by the sealing element 80, the sealing performance of the sealing element 80 deteriorates during long-term use of the single battery 100, making the inner end face 121 area around the mounting hole 1201 susceptible to oxidation and corrosion. By aligning the edge of the first through hole 31 with the edge of the mounting hole 1201, the liquid-retaining layer 30 can be extended to the vicinity of the outer periphery of the mounting hole 1201 to the maximum extent possible, while ensuring complete avoidance of the mounting hole 1201, thus covering as much of the area of ​​the inner end face 121 around the mounting hole 1201 as possible, forming an effective liquid seal around the electrode 60.

[0159] Please see Figure 2 In one embodiment of the present invention, the single battery cell 100 further includes an electrode post 60, which includes a post body 61, a first limiting part 62, and a second limiting part 63. The end wall 12 also includes a mounting hole 1201, through which the post body 61 passes. The end wall 12 is sandwiched between the first limiting part 62 and the second limiting part 63. The second limiting part 63 is located outside the housing 10 and is a riveted flange. In this embodiment, the specific structure of the electrode post 60 and the specific installation structure of the electrode post 60 in the mounting hole 1201 can be referred to the relevant descriptions in the foregoing embodiments, and will not be repeated here. The liquid-retaining layer 30 is disposed between the first limiting part 62 and the end wall 12.

[0160] In the above embodiment, the second limiting part 63 of the pole post 60 is configured as a riveted flange structure located outside the housing 10, realizing the external riveting installation of the pole post 60. This configuration can avoid direct impact or compression on the liquid-retaining layer 30 inside the housing 10 during the riveting process, which would affect the liquid-retaining effect of the liquid-retaining layer 30 and thus the liquid-sealing effect. Furthermore, the liquid-retaining layer 30 extends at least partially to the overlapping area of ​​the projections of the first limiting part 62 and the second limiting part 63 on the end wall 12, or extends to be flush with the mounting hole 1201.

[0161] Please see Figure 26 In one embodiment of the present invention, the sidewall 13 of the housing 10 includes an inner surface 131 located within the receiving space 11. The inner surface 131 is connected to the outer periphery of the inner end face 121 to form a transition surface 15. At least a portion of the transition surface 15 is adhered to a liquid-retaining layer 30. The transition surface 15 includes, but is not limited to, a rounded corner surface. Exemplarily, in this embodiment, the transition surface 15 has an approximately rounded corner surface structure. The liquid-retaining layer 30 may completely adhere to and cover the entire area of ​​the transition surface 15, or it may only cover a portion of the transition surface 15 on the side closest to the inner end face 121.

[0162] There are various specific configurations for the liquid-retaining layer 30 attached to the transition surface 15. For example, in one embodiment, the liquid-retaining layer 30 is directly disposed on the inner end face 121 and extends continuously radially outward to the transition surface 15. This method can be achieved through processes such as coating, spraying, or thermal bonding, so that the liquid-retaining layer 30 forms a continuous integral structure between the inner end face 121 and the transition surface 15, without the need for additional connection interfaces, which helps to ensure the continuity and consistency of the liquid seal.

[0163] In another embodiment, a liquid-retaining layer 30 is disposed on the lower insulating member 40. The liquid-retaining layer 30 has a similar shape to the transition surface 15 and is tightly fitted to the transition surface 15. For example, the outer periphery of the lower insulating member 40 can adopt a shape structure that matches the curvature of the transition surface 15. Specifically, the lower insulating member 40 can be made of plastic, foam, etc.

[0164] In this embodiment, the transition surface 15 is located at the junction of the inner end face 121 and the inner side surface 131 of the side wall 13. The thickness of this area is smaller than that of the end wall 12. If this area is corroded, it is more likely to cause safety risks.

[0165] Based on the liquid-retaining layer 30 adhered to the transition surface 15, further please refer to... Figure 27 In one embodiment of the present invention, at least a portion of the inner surface 131 is fitted with a liquid-retaining layer 30. It should be noted that, in this embodiment, at least a portion of the inner surface 131 specifically refers to the area of ​​the inner surface 131 near the inner end face 121. This arrangement allows the inner end face 121, the transition surface 15, and the portion of the inner surface 131 near the transition surface 15 to form a continuous liquid-sealed protection, further reducing the exposed area of ​​the inner surface of the housing 10. This effectively reduces the probability of adverse reactions occurring on the inner surface of the housing 10 in this area, further improving the safety performance and service life of the single-cell battery 100.

[0166] Please see Figure 28In one embodiment of the battery pack 200 of the present invention, the battery pack 200 includes a housing 210 and at least one individual battery cell 100. The housing 210 includes a first housing portion 2101 and a second housing portion 2102, which cover each other to form a receiving space. Multiple individual batteries 100 are housed within the receiving space, and the multiple individual batteries 100 can be connected in series and / or in parallel. The battery pack 200 can be, for example, a battery module, a battery pack, etc.

[0167] Please see Figure 29 In one example of the electronic device 300 of the present invention, the electronic device 300 includes a working part 310 and a battery pack 200. The working part 310 is electrically connected to the battery pack 200 to obtain electrical power. The working part 310 can be a unit component capable of obtaining electrical power from the battery pack 200 and performing corresponding work, such as a fan blade rotation unit, a vacuum cleaner suction unit, or a wheel drive unit in an electric vehicle. The electronic device 300 can be a vehicle, mobile phone, portable device, laptop computer, ship, spacecraft, electric toy, and power tool, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This invention does not impose special limitations on the above-mentioned electronic device 300. In one embodiment of the electronic device 300 of this invention, the electronic device 300 is a vehicle, the working part 310 is the vehicle body, and the battery pack 200 is fixedly installed on the vehicle body, thereby providing driving force for the vehicle and enabling its operation.

[0168] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A single-cell battery, characterized in that, include: A housing, the housing including a receiving space and end walls; Electrode assemblies are housed within the housing space; The end wall includes an inner end face facing the electrode assembly; A liquid-retaining layer is provided between the inner end face and the electrode assembly, and the liquid-retaining layer is attached to at least a portion of the inner end face.

2. The single-cell battery according to claim 1, characterized in that, The housing also includes sidewalls that enclose the receiving space, wherein: One end of the sidewall is integrally connected to the end wall, and the other end forms an opening; or, at least one end of the sidewall forms an opening, and the end wall is installed on the sidewall and covers at least one of the openings.

3. The single-cell battery according to claim 1, characterized in that, The end wall is made of carbon steel, stainless steel, or carbon steel with a nickel plating layer on the surface.

4. The single-cell battery according to claim 1, characterized in that, The liquid absorption rate of the liquid-retaining layer is a, where a ≥ 5%.

5. The single-cell battery according to claim 4, characterized in that, a ≤ 2000%。 6. The single-cell battery according to claim 4, characterized in that, The liquid loss rate of the liquid-retaining layer is b, where b ≤ 80%.

7. The single-cell battery according to claim 1, characterized in that, The liquid-retaining layer is fixed to the inner end face, or a lower insulating member is provided between the electrode assembly and the end wall, and the liquid-retaining layer is fixed to the surface of the lower insulating member facing the inner end face.

8. The single-cell battery according to claim 7, characterized in that, An adhesive layer is provided between the liquid-retaining layer and the lower insulating component, and the liquid-retaining layer is bonded to the lower insulating component through the adhesive layer.

9. The single-cell battery according to claim 8, characterized in that, The distance between the edge of the liquid-retaining layer and the edge of the lower insulating member is L1, L1≤3.0mm; and / or, the distance between the edge of the liquid-retaining layer and the edge of the adhesive layer is L2, L2≤3.0mm.

10. The single-cell battery according to claim 9, characterized in that, Along the thickness direction of the lower insulating component, the projection of the adhesive layer falls completely within the projection of the liquid-retaining layer, and the projection of the liquid-retaining layer falls completely within the projection of the lower insulating component, where 0 < L1 < L2.

11. The single-cell battery according to claim 8, characterized in that, The single cell also includes an electrode post, the end wall of which is provided with a mounting hole, and the lower insulating member includes a first part and a second part; the first part is disposed between the inner end face and the electrode assembly, and at least a portion of the second part passes through the first through hole of the liquid-retaining layer and the second through hole of the adhesive layer in sequence and extends into the mounting hole; the electrode post passes through the second part and is electrically connected to the electrode assembly.

12. The single-cell battery according to claim 11, characterized in that, The first part and the second part are separate. The liquid-retaining layer is disposed in the first part. The first part is provided with a third through hole. The edge of the third through hole is flush with the edge of the first through hole or along the radial direction of the first through hole. The distance between the edge of the third through hole and the edge of the first through hole is less than or equal to 3.0 mm.

13. The single-cell battery according to claim 11, characterized in that, The liquid-retaining layer is disposed in the first part, the thickness of the first part is W1, 0.05mm ≤W1≤ 5.0mm, and the thickness of the liquid-retaining layer is W3, 0.01mm ≤W3≤2.0mm.

14. The single-cell battery according to claim 1, characterized in that, A lower insulating member is further provided between the electrode assembly and the end wall, and the liquid-retaining layer is thermally bonded to the lower insulating member; or, the liquid-retaining layer is thermally bonded to the end wall.

15. The single-cell battery according to claim 14, characterized in that, A transition layer is also provided between the liquid-retaining layer and the lower insulating component, and the transition layer is softened or melted and then solidified during the thermal bonding process.

16. The single-cell battery according to claim 1, characterized in that, The liquid-retaining layer is made of porous inorganic materials, polymer materials, or fiber materials; preferably, it is any one of non-woven fabric, expanding adhesive, or gel.

17. The single-cell battery according to claim 1, characterized in that, The liquid-retaining layer is made of expanding adhesive, and the expansion rate of the expanding adhesive is c, where 120% ≤ c ≤ 400%.

18. The single-cell battery according to claim 1, characterized in that, A lower insulating component is also provided between the electrode assembly and the end wall. The liquid-retaining layer is formed on the inner end face by coating or spraying, or the liquid-retaining layer is formed on the lower insulating component by coating or spraying.

19. The single-cell battery according to claim 1, characterized in that, The melting point of the liquid-retaining layer is above 60°C, and the embrittlement temperature is below -20°C.

20. The single-cell battery according to claim 1, characterized in that, A lower insulating member is also provided between the electrode assembly and the end wall. The liquid-retaining layer is fixed to the surface of the lower insulating member facing the inner end face. The electrode assembly presses against the lower insulating member so that the liquid-retaining layer adheres to the end wall.

21. The single-cell battery according to claim 1, characterized in that, The bonding area between the liquid-retaining layer and the inner end face is S1, the total area of ​​the inner end face is S2, and 5% ≤ S1 / S2.

22. The single-cell battery according to claim 1, characterized in that, A lower insulating member is also provided between the electrode assembly and the end wall. The liquid-retaining layer is fixed to the lower insulating member. The porosity of the surface of the liquid-retaining layer facing the inner end face is d, where 5%≤d≤60%.

23. The single-cell battery according to claim 1, characterized in that, The single cell also includes an electrode post, the end wall also includes a mounting hole, the liquid-retaining layer is provided with a first through hole, the electrode post passes through the mounting hole and is electrically connected to the electrode assembly through the first through hole; the edge of the first through hole is flush with the edge of the mounting hole.

24. The single-cell battery according to claim 1, characterized in that, The single battery cell further includes an electrode post, which includes a column portion, a first limiting portion, and a second limiting portion; the end wall also includes a mounting hole, the column portion passing through the mounting hole, and the end wall being clamped between the first limiting portion and the second limiting portion. The first limiting portion is located inside the housing, and the second limiting portion is located outside the housing and is a riveted flange; the liquid-retaining layer is disposed between the first limiting portion and the end wall.

25. The single-cell battery according to claim 1, characterized in that, The housing also includes a sidewall surrounding the end wall, the sidewall including an inner sidewall located within the receiving space, the inner sidewall being connected to the outer periphery of the inner end face via a transition surface, and the transition surface having at least a portion of the liquid-retaining layer attached to it.

26. The single-cell battery according to claim 25, characterized in that, The liquid-retaining layer is attached to at least a portion of the inner surface.

27. A battery pack, characterized in that, The single cell battery includes any one of claims 1 to 26.

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