Single battery

Abstract

The utility model discloses a single battery which comprises a shell and a sealing assembly, specifically, an accommodating space is formed in the shell, and a liquid injection hole communicated with the accommodating space is further formed in the surface of the shell; the sealing assembly comprises a heat sealing film, the liquid injection hole is blocked by the heat sealing film, and the heat sealing film is used for being melted at the preset temperature. Compared with the prior art, the structure of the single battery is simplified on the premise that the pressure relief emergency function is reserved, and the simplified and miniaturized design of energy storage equipment is facilitated.

Description

Technical Field

[0001] This utility model relates to the field of energy storage technology, and in particular to a single-cell battery. Background Technology

[0002] During the charging and discharging process of lithium-ion batteries, side reactions between the electrolyte and electrode materials continuously generate gas. Simultaneously, the increased internal temperature of the battery exacerbates the thermal decomposition of the electrolyte and the thermal expansion of the battery contents, further leading to internal pressure accumulation. Especially under conditions of external short circuits, overcharging, and other forms of thermal abuse, the internal temperature of the battery surges, further increasing the gas production rate. If the pressure cannot be released in time, it can cause casing deformation, seal failure, and even the risk of explosion.

[0003] To address the issue of rising internal pressure, a common existing technology involves installing a mechanical pressure relief valve in the battery casing or top cover. The working principle typically involves pre-forming grooves or micro-fracture structures, such as explosion-proof membranes or grooved channels, in weak areas of the casing. When the internal pressure reaches a critical threshold, stress concentration at the grooves causes the casing to rupture, creating a momentary pressure relief vent to release gas. While this design can prevent battery explosions, it relies on precise control of the groove depth, shape, and material fracture toughness to ensure that the pressure relief action is strictly matched to the pressure threshold.

[0004] However, the independent placement of the pressure relief valve requires additional space to be allocated for its installation, significantly increasing the complexity of the casing structure. For example, cylindrical batteries need to integrate an explosion-proof valve assembly in the top cover, while prismatic hard-shell batteries often require grooved structures machined on the side walls. This not only occupies the effective volume that could be used for filling electrode active materials, reducing energy density, but also increases the difficulty of the casing stamping process and reduces yield. In addition, the spatial arrangement conflict between the pressure relief valve and the inherent structure of individual cells such as the injection hole and terminals further restricts the miniaturization design of batteries, making it difficult to meet the compact battery requirements of consumer electronics devices. Utility Model Content

[0005] One objective of this invention is to provide a single-cell battery that addresses the technical problem of miniaturization caused by the conflict between the pressure relief valve and the inherent structural dimensions of the battery.

[0006] To achieve the above objectives, the present invention provides a solution as follows: a single battery cell, the single battery cell including a casing and a sealing assembly, specifically: an accommodating space is formed inside the casing, and an injection hole communicating with the accommodating space is also provided on the surface of the casing; the sealing assembly includes a heat-sealing film, the heat-sealing film sealing the injection hole, the heat-sealing film being used to melt at a preset temperature.

[0007] According to some embodiments of the present invention, the sealing assembly further includes a bottom ring with a through pressure relief hole, a heat-sealed adhesive sheet sandwiching the bottom ring with the housing, an injection hole communicating with the pressure relief hole, and the heat-sealed adhesive sheet sealing the side of the pressure relief hole away from the housing.

[0008] According to some embodiments of this utility model, the thickness of the bottom ring is L1, where 0.05mm≤L1≤0.2mm.

[0009] According to some embodiments of this utility model, the diameter of the injection hole is D1, the diameter of the pressure relief hole is D2, and 0.5mm≤D2≤D1≤2mm.

[0010] According to some embodiments of the present invention, the sealing assembly further includes a top plate, which is disposed on the side of the heat-sealing sheet away from the housing and is attached to the heat-sealing sheet.

[0011] According to some embodiments of this utility model, the thickness of the top sheet is L2, where 0.05mm≤L2≤0.2mm.

[0012] According to some embodiments of the present invention, the sealing assembly includes a bottom ring, a heat-sealing film, and a top piece stacked sequentially along the direction away from the housing. A pressure relief hole is formed on the inner side of the bottom ring, and the injection hole communicates with the pressure relief hole. The heat-sealing film covers the end of the pressure relief hole away from the housing. The outer contours of the bottom ring, the heat-sealing film, and the top piece are all elliptical.

[0013] According to some embodiments of this utility model, the diameter of the pressure relief hole is D2, the major axis length of the top piece is D3, the major axis length of the heat-sealed film is D4, the major axis length of the bottom ring is D5, and the effective sealing distance of the sealing assembly in its major axis direction is L3 = min{D3, D4, D5} - D2; the minor axis length of the top piece is D6, the minor axis length of the heat-sealed film is D7, the minor axis length of the bottom ring is D8, and the effective sealing distance of the sealing assembly in its minor axis direction is L4 = min{D6, D7, D8} - D2; 0.5mm ≤ L4 ≤ L3.

[0014] According to some embodiments of this utility model, the thickness of the heat-sealing film is L6, where 0.01mm≤L6≤0.1mm.

[0015] According to some embodiments of this utility model, the sealing assembly includes a bottom ring, a heat-sealing film, and a top piece stacked sequentially along the direction away from the housing. A pressure relief hole is formed on the inner side of the bottom ring, and the injection hole communicates with the pressure relief hole. The heat-sealing film covers the end of the pressure relief hole away from the housing. The outer contours of the bottom ring, the heat-sealing film, and the top piece are all circular. The diameter of the pressure relief hole is D2, the diameter of the top piece is D9, the diameter of the heat-sealing film is D10, and the diameter of the bottom ring is D11. The effective sealing distance L5 of the sealing assembly is min{D9, D10, D11}-D2, where 0.53mm≤L5.

[0016] According to some embodiments of the present invention, the housing includes a top cover and a shell sleeve, the top cover covering the shell sleeve to form an accommodating space, and the top cover having an electrode post hole and an injection hole; the single cell also includes an electrode post and a winding core, the winding core being disposed in the accommodating space, and the electrode post passing through the electrode post hole and electrically connected to the winding core.

[0017] The beneficial effects of this utility model are as follows:

[0018] The housing has an internal accommodating space, and an injection port communicating with the accommodating space is also provided on the surface of the housing. The sealing assembly includes a heat-sealing film that seals the injection port and is used to melt at a preset temperature. The injection port of the housing serves as both an electrolyte filling channel and a pressure relief outlet. The sealing assembly, which also functions as a pressure relief device, is directly sealed at the injection port, eliminating the need for a separate installation space required for a pressure relief valve in existing technologies.

[0019] By structurally coupling the liquid injection hole in the casing with the heat-sealing assembly, the single-cell battery of this application achieves integrated sealing and pressure relief functions. Compared with the prior art, the single-cell battery of this application simplifies the structure while retaining the emergency pressure relief function, which is beneficial for the simplified and miniaturized design of energy storage devices. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the overall structure of a single battery provided in an embodiment of this utility model;

[0022] Figure 2 This is a top view of a single battery provided in an embodiment of this utility model;

[0023] Figure 3 It is along Figure 1 Schematic diagram of the cross section of line AA;

[0024] Figure 4 yes Figure 3 A magnified view of a portion of region B in the middle;

[0025] Figure 5 It is along Figure 2 A cross-sectional view of the middle CC line;

[0026] Figure 6 This is a schematic diagram of the overall structure of a single battery provided in another embodiment of the present invention;

[0027] Figure 7 It is along Figure 6 A cross-sectional schematic diagram of the DD line.

[0028] Explanation of icon numbers:

[0029] 10. Housing; 11. Accommodation space; 12. Top cover; 121. Injection hole; 122. Pole post hole; 13. Shell sleeve; 20. Sealing assembly; 21. Heat-sealing film; 22. Bottom ring; 221. Pressure relief hole; 23. Top plate; 30. Core; 40. Pole post. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] Please see Figures 1 to 5 As shown, Figure 1 This is a schematic diagram of the overall structure of a single battery provided in an embodiment of this utility model; Figure 2 This is a top view of a single battery provided in an embodiment of this utility model; Figure 3 It is along Figure 1 Schematic diagram of the cross section of line AA; Figure 4 yes Figure 3 A magnified view of a portion of region B in the middle; Figure 5 It is along Figure 2 A cross-sectional view of the CC line.

[0032] In the prior art, in order to release excessive pressure inside a single battery cell and prevent accidents such as explosions caused by pressure accumulation, a pressure relief valve is usually installed on the casing 10 of the single battery cell. However, the spatial arrangement of the pressure relief valve and the inherent structure of the single battery cell, such as the liquid injection hole 121 and the terminal post 40, further restricts the miniaturization design of the battery and makes it difficult to meet the demand for compact batteries in consumer electronic devices.

[0033] To address the aforementioned deficiencies in the prior art, the present invention provides a solution: a single-cell battery, comprising a housing 10 and a sealing assembly 20. Specifically, the housing 10 has an internal accommodating space 11, and the surface of the housing 10 is provided with an injection hole 121 communicating with the accommodating space 11; the sealing assembly 20 includes a heat-sealing film 21, which seals the injection hole 121 and is used to melt at a preset temperature.

[0034] The single-cell battery provided in this embodiment improves upon the inherent structure of the single-cell battery, enabling the injection port 121 and its sealing assembly 20 to also function as a pressure relief valve. The interior of the housing 10 forms a cylindrical housing space 11 for accommodating the electrode assembly. An injection port 121 for injecting electrolyte is provided at the top of the housing 10, penetrating the surface of the housing 10 and communicating with the housing space 11. The sealing assembly 20 includes at least a heat-sealing adhesive sheet 21 for sealing the injection port 121. The heat-sealing adhesive sheet 21 can optionally be directly bonded to seal the injection port 121 using a hot-pressing process, or it can be sealed by welding other structures to the housing 10. The heat-sealing adhesive sheet 21 is a rigid solid at room temperature, forming an airtight adhesive interface with the edge of the injection port 121 in the housing 10, effectively preventing electrolyte evaporation and water / oxygen permeation from the outside of the battery.

[0035] When the temperature inside the battery rises to the critical temperature of the heat-sealing film 21 due to abnormal heating, the heat-sealing film 21 melts. Driven by the gas pressure inside the single cell, the molten adhesive flows away from the containment space 11 until the heat-sealing film 21 is broken to form a pressure relief channel. This allows the fluid contents inside the single cell, such as electrolyte and gaseous byproducts generated by the reaction, to be quickly discharged through the injection hole 121, alleviating the emergency situation of excessive internal pressure in the single cell.

[0036] For example, the housing 10 may be an aluminum alloy stamping structure; the heat-sealing film 21 may be made of polypropylene (PP) material with a melting point of 80°C-160°C.

[0037] According to some embodiments of the present invention, the sealing assembly 20 further includes a bottom ring 22, the bottom ring 22 having a through pressure relief hole 221, the heat-sealing film 21 sandwiching the bottom ring 22 with the housing 10, the liquid injection hole 121 communicating with the pressure relief hole 221, and the heat-sealing film 21 sealing the side of the pressure relief hole 221 away from the housing 10.

[0038] In this embodiment, the bottom ring 22 serves as the medium connecting the sealing assembly 20 and the housing 10, avoiding direct connection between the heat-sealing film 21 and the housing 10, and improving the processing accuracy of the heat-sealing film 21.

[0039] Specifically, in the process of directly hot-pressing the heat-sealing film 21 to the shell 10, the heat-sealing film 21 is subjected to both heat and pressure, which results in a large deformation of the heat-sealing film 21. The dimensional tolerance caused by this process requires a large design allowance during the design phase, which reduces the design accuracy of the individual battery.

[0040] In this embodiment, the heat-sealing film 21 is first assembled with the bottom ring 22 to form a sealing assembly 20 on the parts production line. Existing technology can perform this assembly step relatively maturely without producing significant dimensional changes. Then, the bottom ring 22 is welded to the housing 10 to seal the liquid injection hole 121. During the assembly process of the sealing assembly 20 and the housing 10, the heat-sealing film 21 is only heated and almost not subjected to pressure. Moreover, under low-power welding conditions, the heat-sealing film 21 may not even reach its melting point. This allows the heat-sealing film 21 of the single cell formed in this embodiment to maintain high dimensional accuracy, which is beneficial for design and production.

[0041] Furthermore, the thickness of the bottom ring 22 is L1, 0.05mm≤L1≤0.2mm.

[0042] The thickness of the bottom ring 22 is related to the structural strength of the sealing assembly 20. If the bottom ring 22 is too thin, its mechanical strength is insufficient, and it is prone to thermal deformation or tearing during welding, leading to failure of the bonding interface of the heat-sealed adhesive sheet 21. If the bottom ring 22 is too thick, thermal stress concentration during welding will easily cause deformation, and an excessively thick bottom ring 22 will occupy additional space, which is not conducive to lightweight design. When the thickness of the bottom ring 22 is limited to 0.05mm≤L1≤0.2mm, a balance can be achieved between structural rigidity, thermal stress dispersion, and process reliability. L1 is preferably 0.1mm. At this time, the bottom ring 22 can be as thin and light as possible while ensuring its own strength, which not only ensures the airtightness of the welding interface but also avoids wasting space.

[0043] Optionally, the diameter of the injection hole 121 is D1, and the diameter of the pressure relief hole 221 is D2, where 0.5mm≤D2≤D1≤2mm.

[0044] The diameters of the injection hole 121 and the pressure relief hole 221 are related to the smooth discharge of high-pressure contents. The diameter D1 of the injection hole 121 is limited by the parameters of the individual cell and is usually a fixed value. If the pressure relief hole 221 is too small, the cross-sectional area of ​​the pressure relief hole 221 will be too small, the flow resistance of the contents will increase, the flow velocity will decrease, and it will easily lead to delayed pressure relief or carbonization of the contents clogging the pressure relief hole 221. If the diameter of the pressure relief hole 221 is larger than the diameter of the injection hole 121, there will be a pressure drop when the contents rush from the injection hole 121 into the pressure relief hole 221, making it difficult to open the heat-sealed film 21. When the diameters D1 of the injection hole 121 and D2 of the pressure relief hole 221 are limited to 0.5mm≤D2≤D1≤2mm, a better fluid conduction efficiency can be obtained. The preferred diameters are D2 = 0.8 mm and D1 = 1.2 mm. At this diameter, the cross-sectional area ratio of the pressure relief hole 221 to the liquid injection hole 121 ensures that the contents of the fluid can quickly and directionally contract and increase pressure. At the same time, the stepped hole diameter design disperses the fluid impact force and avoids the heat-sealed film 21 from being delayed in opening due to sudden changes in back pressure.

[0045] According to some embodiments of the present invention, the sealing assembly 20 further includes a top piece 23, which is disposed on the side of the heat-sealing sheet 21 away from the housing 10 and is attached to the heat-sealing sheet 21.

[0046] On the one hand, the arrangement of the top plate 23 changes the orientation of the open channel of the heat-sealed sheet 21. When the sealing assembly 20 includes only the heat-sealed sheet 21 and not the top plate 23, damage to the heat-sealed sheet 21 mostly occurs in the area directly opposite the injection hole 121, and the actual thickness of the material sealing the injection hole 121 is the thickness of the heat-sealed sheet 21 itself. However, when the top plate 23 is attached to the heat-sealed sheet 21, provided that the strength of the top plate 23 is sufficient, the internal pressure of the single cell can only be output along the surface of the top plate 23, that is, in the radial direction of the heat-sealed sheet 21. This increases the effective sealing distance of the heat-sealed sheet 21 in the sealed state and increases the airtightness of the sealing assembly 20.

[0047] On the other hand, when the heat-sealed film 21 melts and opens the pressure relief channel, the heat-sealed film 21 and the top sheet 23 in areas other than the channel will undergo certain elastic deformation. When the internal pressure of the single cell is released and there is no longer high-pressure gas in the pressure relief channel to maintain its openness, the stress stored in the top sheet 23 and the heat-sealed film 21 due to deformation is released, and the pressure relief channel is compressed. When the temperature drops below the melting point, the molten colloid re-solidifies, realizing the self-closure of the pressure relief hole 221. Compared with the single cell with pressure relief valve in the prior art, the technical solution of this embodiment makes it less likely for the contents of the single cell to leak when repairing or replacing a faulty single cell, reducing the working risk for operators.

[0048] It should be noted that the elastic deformation of the aforementioned heat-sealed film 21 and top sheet 23 should be understood as follows: during the opening of the pressure relief channel, the opening of the pressure relief channel causes one end of the top sheet 23 to tilt relative to the casing 10, thus storing elastic potential energy in the unmelted portions of the top sheet 23 and the heat-sealed film 21. During this process, plastic deformation of the top sheet 23 or rheological changes in the heat-sealed film 21 may also occur. The existence of these two situations only affects the efficiency of the pressure relief channel closure. Due to the existence of elastic deformation, the pressure relief channel will always tend to close after the internal pressure of the single cell is released.

[0049] Furthermore, the thickness of the top sheet 23 is L2, 0.05mm≤L2≤0.2mm.

[0050] If the thickness of the top plate 23 is too small, it will undergo plastic deformation during the opening of the pressure relief channel, making it difficult to store elastic potential energy for subsequent pressure relief channel closure. If the thickness of the top plate 23 is too large, it will hardly deform during the opening of the pressure relief channel, failing to store elastic potential energy and increasing the tensile stress in the thickness direction of the heat-sealing film 21, exacerbating the rheological changes of the heat-sealing film 21, making it difficult for the heat-sealing film 21 itself to store energy. Therefore, configuring the thickness range of the top plate 23 to be 0.05mm≤L2≤0.2mm allows the top plate 23 to generate appropriate elastic deformation during the opening of the pressure relief channel, which is beneficial for the closure of the pressure relief channel after the internal pressure is released.

[0051] According to some embodiments of the present invention, the sealing assembly 20 includes a bottom ring 22, a heat-sealing sheet 21, and a top piece 23 stacked sequentially along the direction away from the housing 10. A pressure relief hole 221 is formed on the inner side of the bottom ring 22, and the injection hole 121 communicates with the pressure relief hole 221. The heat-sealing sheet 21 covers the end of the pressure relief hole 221 away from the housing 10. The outer contours of the bottom ring 22, the heat-sealing sheet 21, and the top piece 23 are all elliptical.

[0052] The outer contours of each component in the sealing assembly 20 are designed in an elliptical shape, which optimizes the uniformity of circumferential stress distribution and the adaptability of the assembly space. Compared with a circular structure, the major axis of the ellipse can match the asymmetrical layout inside the housing 10, shorten the distance from the sealing surface to the side wall of the housing 10, and effectively avoid the risk of assembly interference. This is especially useful in the design of automotive single-cell batteries with a large length-to-width ratio.

[0053] It should be noted that the outer contour in this application should be understood as the shape of the orthographic projection of the corresponding structure of the sealing component 20 onto the surface of the housing 10 to which it is connected.

[0054] Furthermore, the diameter of the pressure relief hole 221 is D2, the major axis length of the top piece 23 is D3, the major axis length of the heat-sealed film 21 is D4, the major axis length of the bottom ring 22 is D5, and the effective sealing distance of the sealing assembly 20 in its major axis direction is L3 = min{D3, D4, D5} - D2; the minor axis length of the top piece 23 is D6, the minor axis length of the heat-sealed film 21 is D7, the minor axis length of the bottom ring 22 is D8, and the effective sealing distance of the sealing assembly 20 in its minor axis direction is L4 = min{D6, D7, D8} - D2; 0.5mm ≤ L4 ≤ L3.

[0055] With the top sheet 23 in place, the sizes of L3 and L4 determine the sealing capability of the heat-sealed film 21. Without considering damage to the top sheet 23 or welding failure of the bottom ring 22, the sealing capability of the heat-sealed film 21 also represents the sealing capability of the sealing assembly 20. The larger L3 and L4 are, the more difficult it is for the contents of the individual battery to breach the heat-sealed film 21 and form a pressure relief channel. A value of 0.5mm ≤ L4 ≤ L3 gives the sealing assembly 20 strong airtightness, making it difficult to breach at the normal operating temperature of the individual battery, and allowing pressure relief only when the individual battery experiences thermal runaway.

[0056] Optionally, the thickness of the heat-sealing film 21 is L6, where 0.01mm≤L6≤0.1mm.

[0057] When the heat-sealed sheet 21 is sandwiched between the top plate 23 and the bottom ring 22, the heat-sealed sheet 21 hardly bears any sealing function in the thickness direction. The thickness of the heat-sealed sheet 21 is related to the structural stability of the sealing assembly 20 itself. If the heat-sealed sheet 21 is too thin, it is easy to cause pressure penetration when the top plate 23 and the bottom ring 22 are heat-pressed together, which affects the structural integrity and also reduces the effective sealing distance. 0.01mm≤L6≤0.1mm can minimize the thickness of the sealing assembly while ensuring a high yield rate during the processing of the sealing assembly 20, which is beneficial to the lightweight design of the single cell.

[0058] Please see Figure 6 and Figure 7 As shown, Figure 6 This is a schematic diagram of the overall structure of a single battery provided in another embodiment of the present invention; Figure 7 It is along Figure 6 A cross-sectional schematic diagram of the DD line.

[0059] According to some embodiments of the present invention, the sealing assembly 20 includes a bottom ring 22, a heat-sealing sheet 21, and a top piece 23 stacked sequentially along the direction away from the housing 10. A pressure relief hole 221 is formed on the inner side of the bottom ring 22, and the injection hole 121 communicates with the pressure relief hole 221. The heat-sealing sheet 21 covers the end of the pressure relief hole 221 away from the housing 10. The outer contours of the bottom ring 22, the heat-sealing sheet 21, and the top piece 23 are all circular. The diameter of the pressure relief hole 221 is D2, the diameter of the top piece 23 is D9, the diameter of the heat-sealing sheet 21 is D10, and the diameter of the bottom ring 22 is D11. The effective sealing distance L5 of the sealing assembly 20 is min{D9, D10, D11}-D2, and 0.53mm≤L5.

[0060] With the top sheet 23 in place, the size of L5 determines the sealing capability of the heat-sealed sheet 21. Without considering damage to the top sheet 23 or welding failure of the bottom ring 22, the sealing capability of the heat-sealed sheet 21 also represents the sealing capability of the sealing assembly 20. The larger L5 is, the more difficult it is for the contents of the individual battery to breach the heat-sealed sheet 21 and form a pressure relief channel. A L5 of 0.53mm ≤ L5 gives the sealing assembly 20 strong airtightness, making it difficult to be breached at the normal operating temperature of the individual battery, and allowing pressure relief only in the event of thermal runaway in the individual battery.

[0061] According to some embodiments of the present invention, the housing 10 includes a top cover 12 and a housing 13. The top cover 12 covers the housing 13 to form an accommodating space 11. The top cover 12 has an electrode post hole 122 and an injection hole 121. The single battery also includes an electrode post 40 and a winding core 30. The winding core 30 is disposed in the accommodating space 11. The electrode post 40 passes through the electrode post hole 122 and is electrically connected to the winding core 30.

[0062] During the operation of a single battery cell, one end of the terminal post 40 is connected to the core 30, and the other end is connected to the aluminum busbar. Both ends of the terminal post 40 have significant resistance, making them hotspots for heat accumulation in the battery cell. In the event of thermal runaway due to overload, the area near the terminal post 40 is also typically a point of high voltage generation. By placing the sealing assembly 20 and the terminal post 40 on the same cover plate, and bringing the heat-sealing film 21 close to the terminal post 40, a faster pressure relief response can be achieved when the internal pressure of the battery cell rises due to thermal runaway, further reducing the risk of battery cell explosion.

[0063] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture. If the specific posture changes, the directional indicator will also change accordingly.

[0064] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0065] Furthermore, the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this utility model.

[0066] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the design concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A single cell, characterized by, include: The shell has an internal accommodating space, and the surface of the shell is provided with an injection hole communicating with the accommodating space; A sealing assembly includes a heat-sealing sheet that seals the injection hole and is designed to melt at a preset temperature.

2. The cell according to claim 1, wherein The sealing assembly also includes a bottom ring with a through pressure relief hole. The heat-sealing sheet sandwiches the bottom ring with the housing. The injection hole communicates with the pressure relief hole. The heat-sealing sheet covers the side of the pressure relief hole away from the housing.

3. The cell according to claim 2, wherein The thickness of the bottom ring is L1, where 0.05mm ≤ L1 ≤ 0.2mm.

4. The cell according to claim 2, wherein The diameter of the injection hole is D1, and the diameter of the pressure relief hole is D2, where 0.5mm ≤ D2 ≤ D1 ≤ 2mm.

5. The cell according to claim 1, wherein The sealing assembly further includes a top plate, which is disposed on the side of the heat-sealing sheet away from the housing and is fitted to the heat-sealing sheet.

6. The cell according to claim 5, wherein The thickness of the top sheet is L2, where 0.05mm ≤ L2 ≤ 0.2mm.

7. The single cell according to any one of claims 1 to 6, characterized in that, The sealing assembly includes a bottom ring, a heat-sealing film, and a top piece stacked sequentially in a direction away from the housing. A pressure relief hole is formed on the inner side of the bottom ring, and the liquid injection hole communicates with the pressure relief hole. The heat-sealing film covers the end of the pressure relief hole away from the housing. The outer contours of the bottom ring, the heat-sealing film, and the top piece are all elliptical.

8. The cell according to claim 7, wherein The diameter of the pressure relief hole is D2, the length of the major axis of the top plate is D3, the length of the major axis of the heat-sealing film is D4, the length of the major axis of the bottom ring is D5, and the effective sealing distance of the sealing assembly in its major axis direction is L3 = min{D3, D4, D5} - D2; The short axis length of the top piece is D6, the short axis length of the heat-sealing film is D7, the short axis length of the bottom ring is D8, and the effective sealing distance of the sealing assembly in its short axis direction is L4 = min{D6, D7, D8} - D2; 0.5mm≤L4≤L3.

9. The cell according to claim 7, wherein The thickness of the heat-sealing film is L6, where 0.01mm ≤ L6 ≤ 0.1mm.

10. The single cell according to any one of claims 1 to 6, wherein, The sealing assembly includes a bottom ring, a heat-sealing film, and a top piece stacked sequentially in a direction away from the housing. A pressure relief hole is formed on the inner side of the bottom ring. The liquid injection hole communicates with the pressure relief hole. The heat-sealing film covers the end of the pressure relief hole away from the housing. The outer contours of the bottom ring, the heat-sealing film, and the top piece are all circular. The diameter of the pressure relief hole is D2, the diameter of the top plate is D9, the diameter of the heat-sealing film is D10, the diameter of the bottom ring is D11, and the effective sealing distance of the sealing assembly is L5 = min{D9, D10, D11} - D2, 0.53mm ≤ L5.

11. The single cell according to any one of claims 1 to 6, wherein, The housing includes a top cover and a shell sleeve. The top cover covers the shell sleeve to form an accommodating space. The top cover has an electrode hole and an injection hole. The single battery cell also includes a terminal post and a winding core. The winding core is disposed within the accommodating space, and the terminal post passes through the terminal post hole and is electrically connected to the winding core.

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