Battery cell, battery pack and energy storage system

Abstract

A battery cell, a battery pack and an energy storage system. The battery cell comprises a casing (10) and an inner core (20), wherein the casing (10) has an accommodating cavity (11); and the inner core (20) is arranged in the accommodating cavity (11) and is spaced apart from a first bottom plate (12) of the casing (10) to form an exhaust channel (30). The inner core (20) comprises a positive electrode sheet (21), a separator (22) and a negative electrode sheet (23), which are stacked, wherein the distance between the edge of the side of the positive electrode sheet (21) away from an explosion-proof valve (121) and the edge of the adjacent separator (22) is greater than the distance between the edge of the side of the positive electrode sheet (21) close to the explosion-proof valve (121) and the edge of the adjacent separator (22), and the distance between the edge of the side of the negative electrode sheet (23) away from the explosion-proof valve (121) and the edge of the adjacent separator (22) is greater than the distance between the edge of the side of the negative electrode sheet (23) close to the explosion-proof valve (121) and the edge of the adjacent separator (22).

Description

Individual cells, battery packs and energy storage systems

[0001] This application claims priority to Chinese Patent Application No. 202520163368.3, filed on January 22, 2025, entitled "Single Battery, Battery Pack and Energy Storage System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to a single battery cell, a battery pack, and an energy storage system. Background Technology

[0003] For stacked cells with tabs on the same side in blade batteries, the explosion-proof valve is on the opposite side of the tabs. During charging and discharging, the temperature on the side closer to the tabs is higher than the temperature on the opposite side. The higher temperature on the tab side can easily cause the diaphragm to shrink more, which reduces the size of the diaphragm covering the electrode, thus leading to a short circuit between the tab and the edge of the corresponding electrode. Summary of the Invention

[0004] The following is an overview of the detailed description of this application. This overview is not intended to limit the scope of the claims.

[0005] In a first aspect, embodiments of this application provide a single-cell battery, comprising:

[0006] The housing has a receiving cavity, and the housing includes a first base plate on which an explosion-proof valve is disposed;

[0007] An inner core is disposed within the receiving cavity. The inner core and the first base plate are spaced apart to form an exhaust channel. The inner core includes a positive electrode sheet, a separator, and a negative electrode sheet stacked together. The separator is disposed between the positive electrode sheet and the negative electrode sheet.

[0008] The distance between the edge of the negative electrode sheet away from the explosion-proof valve and the edge of the adjacent diaphragm is a first distance; the distance between the edge of the negative electrode sheet close to the explosion-proof valve and the edge of the adjacent diaphragm is a second distance; the first distance is greater than the second distance.

[0009] The distance between the edge of the positive electrode away from the explosion-proof valve and the edge of the adjacent diaphragm is a third distance; the distance between the edge of the positive electrode close to the explosion-proof valve and the edge of the adjacent diaphragm is a fourth distance; the third distance is greater than the fourth distance.

[0010] In some embodiments, the inner core further includes:

[0011] A positive electrode tab is disposed on the side of the positive electrode plate away from the explosion-proof valve and is connected to the positive electrode plate;

[0012] The negative electrode tab is located on the side of the negative electrode plate away from the explosion-proof valve and is connected to the negative electrode plate.

[0013] In some embodiments, the outline dimensions of the positive electrode are smaller than those of the negative electrode, and the outline dimensions of the negative electrode are smaller than those of the separator.

[0014] In some embodiments, the size of the explosion-proof valve is proportional to the size of the exhaust passage.

[0015] In some embodiments, the size of the exhaust passage is inversely proportional to the size of the second distance.

[0016] In some embodiments, the first distance is greater than or equal to 6 mm and less than or equal to 10 mm; the second distance is greater than or equal to 1 mm and less than or equal to 4 mm.

[0017] In some embodiments, the third distance is greater than or equal to 8 mm and less than or equal to 12 mm; the fourth distance is greater than or equal to 4 mm and less than or equal to 6 mm.

[0018] In some embodiments, the difference between the first distance and the second distance is greater than or equal to 2 mm and less than or equal to 6 mm;

[0019] The difference between the third distance and the fourth distance is greater than or equal to 3mm and less than or equal to 7mm.

[0020] Secondly, embodiments of this application also provide a battery pack, the battery pack comprising the single battery cells described in any of the above embodiments.

[0021] Thirdly, embodiments of this application also provide an energy storage system, which includes a single battery cell as described in any of the above embodiments, or includes a battery pack as described above.

[0022] Since the temperature on the side away from the explosion-proof valve is typically higher, the separator is prone to thermal shrinkage at high temperatures. In this embodiment, the single-cell battery is designed with a first distance greater than a second distance and a third distance greater than a fourth distance. This ensures that the separator coverage size (first and third distances) on the side away from the explosion-proof valve is larger than the coverage size (second and fourth distances) on the side closer to the explosion-proof valve, providing a "safety margin" for high-temperature shrinkage. Even during thermal shrinkage, the separator can still effectively cover the corresponding positive and negative electrode plates. This ensures that the separator still has sufficient material to cover the electrode edges after shrinkage under high-temperature conditions, maintaining insulation. This reduces the risk of short circuits between the positive electrode tab and the edge of the positive electrode plate, and between the negative electrode tab and the edge of the negative electrode plate. Furthermore, because the separator coverage size near the explosion-proof valve is smaller, the space for the venting channel is optimized. This allows the explosion-proof valve to quickly vent in the event of thermal runaway, reducing heat accumulation and further reducing the risk of thermal runaway. In summary, this not only improves the safety and reliability of the battery but also optimizes the performance of the single-cell battery under extreme conditions.

[0023] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 is a schematic diagram of the overall structure of a single battery provided in an embodiment of this application;

[0026] Figure 2 is a schematic diagram showing the positional relationship between the negative electrode sheet and the separator provided in the embodiment of this application;

[0027] Figure 3 is a schematic diagram showing the positional relationship between the positive electrode and the separator provided in the embodiment of this application;

[0028] Figure 4 is a schematic diagram of the overall structure of the inner core provided in the embodiment of this application;

[0029] Figure 5 is a schematic diagram showing the positional relationship of the positive electrode, negative electrode, and separator provided in the embodiments of this application.

[0030] Explanation of reference numerals in the attached figures:

[0031] 10-Shell; 11-Receiving cavity; 12-First base plate; 121-Explosion-proof valve;

[0032] 20-Inner core; 21-Positive electrode plate; 22-Separator; 23-Negative electrode plate; 24-Positive electrode tab; 25-Negative electrode tab;

[0033] 30 - Exhaust passage. Embodiments of the present invention

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0035] It should be understood that although the terms "first," "second," etc., may be used in this document to describe various components, these components should not be limited by these terms. These terms are used to distinguish one component from another.

[0036] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of exemplary embodiments and may not be to scale. The modules or processes shown in the drawings are not necessarily essential for implementing this application and therefore should not be used to limit the scope of protection of this application.

[0037] Traditional blade battery cell structures employ tabs at both ends, with the explosion-proof valve 121 located on one side of the tabs. During charging and discharging, the temperature of the two tabs is higher, while the temperature in the middle is lower, resulting in a small temperature difference between the two tabs. Therefore, in stacked cell designs, the size of the diaphragm 22 covering the negative electrode remains consistent on both sides. However, for stacked cells with tabs on the same side, the explosion-proof valve 121 is located on the opposite side of the tab. During charging and discharging, the side closer to the tab experiences a higher temperature, while the opposite side remains cooler. The high temperature on the tab side can easily lead to increased shrinkage of the diaphragm 22, thereby reducing the size of the diaphragm 22 covering the electrode and increasing the risk of short circuit between the tab and the corresponding electrode edge. In addition, since the non-electrode side is close to the explosion-proof valve 121, sufficient exhaust channels 30 need to be reserved so that the explosion-proof valve 121 can open in time during thermal runaway. However, in the related technology, the diaphragm 22 covers a large area of ​​the negative electrode, resulting in insufficient space for the exhaust channels 30. This may delay the opening time of the explosion-proof valve 121, causing heat to accumulate in the cell and not be released in time, thereby increasing the risk of thermal runaway of the cell.

[0038] In view of this, this application provides a single-cell battery to solve the potential short-circuit risk caused by the high temperature on the tab side during the charging and discharging process of traditional stacked cells, as well as the problem of delayed opening of the explosion-proof valve 121.

[0039] Please refer to Figures 1, 2, 3, and 4. Figure 1 is a schematic diagram of the overall structure of a single battery provided in this embodiment; Figure 2 is a schematic diagram of the positional relationship between the negative electrode 23 and the separator 22 provided in this embodiment; Figure 3 is a schematic diagram of the positional relationship between the positive electrode 21 and the separator 22 provided in this embodiment; and Figure 4 is a schematic diagram of the overall structure of the inner core 20 provided in this embodiment. In this embodiment, the single battery includes a housing 10 and an inner core 20. The housing 10 has a receiving cavity 11 and includes a first bottom plate 12, on which an explosion-proof valve 121 is disposed. The inner core 20 is disposed within the receiving cavity 11, and the inner core 20 and the first bottom plate 12 are spaced apart to form an exhaust channel 30. The inner core 20 includes a positive electrode 21, a separator 22, and a negative electrode 23 stacked together, with the separator 22 disposed between the positive electrode 21 and the negative electrode 23.

[0040] The distance between the edge of the negative electrode 23 furthest from the explosion-proof valve 121 and the edge of the adjacent diaphragm 22 is a first distance L1. The distance between the edge of the negative electrode 23 closest to the explosion-proof valve 121 and the edge of the adjacent diaphragm 22 is a second distance L2. The first distance L1 is greater than the second distance L2.

[0041] The distance between the edge of the positive electrode 21 furthest from the explosion-proof valve 121 and the edge of the adjacent diaphragm 22 is a third distance L3. The distance between the edge of the positive electrode 21 closest to the explosion-proof valve 121 and the edge of the adjacent diaphragm 22 is a fourth distance L4. The third distance L3 is greater than the fourth distance L4.

[0042] As shown in Figure 2, the first distance L1 refers to the vertical distance between the edge of the negative electrode 23 away from the explosion-proof valve 121 and the corresponding edge of its adjacent separator 22 along the length direction of the single cell (perpendicular to the first base plate 12), indicating the extent to which the separator 22 extends beyond the edge of the negative electrode 23. The second distance L2 refers to the vertical distance between the edge of the negative electrode 23 near the explosion-proof valve 121 and the corresponding edge of its adjacent separator 22 along the length direction of the single cell, indicating the extent to which the separator 22 extends beyond the edge of the negative electrode 23. The third distance L3 refers to the vertical distance between the edge of the positive electrode 21 away from the explosion-proof valve 121 and the corresponding edge of its adjacent separator 22 along the length direction of the single cell, indicating the extent to which the separator 22 extends beyond the edge of the positive electrode 21. The fourth distance L4 refers to the vertical distance between the edge of the positive electrode 21 near the explosion-proof valve 121 and the corresponding edge of the adjacent separator 22 in the length direction of the single cell, and is used to indicate the coverage size of the separator 22 beyond the edge of the positive electrode 21.

[0043] In some embodiments, the single battery cell further includes an electrolyte, and the housing 10 also has an opening to allow the inner core 20 to be received within a receiving cavity 11 of the housing 10. In some embodiments, a first base plate 12 is configured to cover the opening of the housing 10. After the inner core 20 is received in the housing 10, the electrolyte can be injected into the receiving cavity 11 through an injection hole (not shown) provided on the first base plate 12. The shape of the housing 10 depends on the combination of one or more inner cores 20. For example, the housing 10 can be a hollow cuboid, a hollow cube, or a hollow cylinder. In some embodiments of this application, the housing 10 can be made of a conductive metal material, such as aluminum or an aluminum alloy. The housing 10 can also be made of plastic.

[0044] In some embodiments, the battery cell primarily functions by the movement of metal ions between the positive electrode 21 and the negative electrode 23. The positive electrode 21 includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector, and the uncoated positive current collector protrudes beyond the coated positive current collector, serving as a positive electrode tab 24. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide, etc. The negative electrode 23 includes a negative current collector and a negative active material layer. The negative active material layer is coated on the surface of the negative current collector, and the uncoated negative current collector protrudes beyond the coated negative current collector, serving as a negative electrode tab 25. The material of the negative current collector can be copper, and the negative active material can be carbon or silicon, etc. The separator 22 can be made of materials such as PP (polypropylene) or PE (polyethylene). The separator 22 has electronic insulation properties, used to isolate adjacent positive electrode plates 21 and negative electrode plates 23, preventing short circuits between them. The separator 22 has numerous interconnected micropores, allowing electrolyte ions to pass freely and exhibiting excellent permeability to lithium ions; therefore, the separator 22 essentially does not block lithium ions from passing through. Furthermore, the inner core 20 can be a wound structure or a stacked structure; the embodiments of this application are not limited to these.

[0045] As shown in Figure 1, the exhaust channel 30 formed between the inner core 20 and the first base plate 12 allows the explosion-proof valve 121 to open promptly and quickly release the heat inside the single cell in the event of thermal runaway. As shown in Figure 2, for the negative electrode 23, the distance between the edge away from the explosion-proof valve 121 and the edge of the adjacent separator 22 is the first distance L1 (that is, the distance between the boundary of the separator 22 away from the explosion-proof valve 121 and the negative electrode 23 in the length direction of the single cell is the first distance L1), and the distance between the edge closer to the explosion-proof valve 121 and the edge of the adjacent separator 22 is the second distance L2 (that is, the distance between the boundary of the separator 22 closer to the explosion-proof valve 121 and the negative electrode 23 in the length direction of the single cell is the second distance L2). As shown in Figure 3, for the positive electrode 21, the distance between the edge away from the explosion-proof valve 121 and the edge of the adjacent separator 22 is the third distance L3 (that is, the distance between the boundary of the separator 22 away from the explosion-proof valve 121 and the positive electrode 21 along the length of the single cell is the third distance L3), and the distance between the edge closer to the explosion-proof valve 121 and the edge of the adjacent separator 22 is the fourth distance L4 (that is, the distance between the boundary of the separator 22 closer to the explosion-proof valve 121 and the positive electrode 21 along the length of the single cell is the fourth distance L4). In this embodiment, the first distance L1 is greater than the second distance L2, and the third distance L3 is greater than the fourth distance L4. In other words, the size of the corresponding electrode plates covered by the first distance L1 and the third distance L3 on the side away from the explosion-proof valve 121 is larger than the size of the corresponding electrode plates covered by the second distance L2 and the fourth distance L4 on the side closer to the explosion-proof valve 121. That is, the size of the diaphragm 22 extending beyond the corresponding electrode plate on the side away from the explosion-proof valve 121 is larger than the size extending beyond the corresponding electrode plate on the side closer to the explosion-proof valve 121, thereby reducing the risk of short circuit between the positive and negative electrodes due to the shrinkage of the diaphragm 22 on the side away from the explosion-proof valve 121; at the same time, it ensures that there is enough space in the exhaust channel 30 on the side closer to the explosion-proof valve 121 for exhaust.

[0046] In the single-cell battery of this application embodiment, the configuration of a first distance L1 greater than a second distance L2, and a third distance L3 greater than a fourth distance L4, brings significant benefits, especially in terms of thermal management and safety. Since the temperature on the side away from the explosion-proof valve 121 is typically higher, the separator 22 is prone to thermal shrinkage at high temperatures. By making the coverage size of the separator 22 on the side away from the explosion-proof valve 121 (the first distance L1 and the third distance L3) greater than the coverage size on the side closer to the explosion-proof valve 121 (the second distance L2 and the fourth distance L4), a "safety margin" is reserved for high-temperature shrinkage. Even in the event of thermal shrinkage, the separator 22 can still effectively cover the corresponding positive electrode 21 and negative electrode 23. This ensures that the separator 22, even under high-temperature conditions, still has sufficient material to cover the electrode edges after shrinkage, maintaining insulation. This reduces the risk of short circuits between the positive electrode tab 24 and the edge of the positive electrode 21, and between the negative electrode tab 25 and the edge of the negative electrode 23.

[0047] Effective coverage by the separator 22 is crucial for preventing internal short circuits in individual cells. By increasing the size of the separator 22 covering the side furthest from the explosion-proof valve 121, it is possible to maintain complete coverage of the electrodes under thermal shrinkage conditions, preventing direct contact between the positive electrode tab 24 and the positive electrode 21, and between the negative electrode tab 25 and the negative electrode 23, thus reducing the risk of short circuits. This improves battery safety, especially under high temperature or overload conditions. This structure helps maintain the thermal stability of individual cells. By ensuring that the separator 22 still covers the positive electrode 21 and the negative electrode 23 at high temperatures, the battery can better cope with temperature changes, reducing the possibility of thermal runaway. This is significant for extending battery life and improving its reliability. Furthermore, because the size of the separator 22 covering the side closer to the explosion-proof valve 121 is smaller, the space for the venting channel 30 can be optimized and made larger. This allows the explosion-proof valve 121 to vent quickly in the event of thermal runaway, reducing heat accumulation and further reducing the risk of thermal runaway. In summary, this structure not only improves the safety and reliability of the battery but also optimizes the performance of individual cells under extreme conditions.

[0048] In some embodiments, as shown in Figures 1, 2, and 3, the inner core 20 further includes a positive electrode tab 24 and a negative electrode tab 25. The positive electrode tab 24 is disposed on the side of the positive electrode plate 21 away from the explosion-proof valve 121 and is connected to the positive electrode plate 21. The negative electrode tab 25 is disposed on the side of the negative electrode plate 23 away from the explosion-proof valve 121 and is connected to the negative electrode plate 23.

[0049] It should be noted that both the positive tab 24 and the negative tab 25 are located on the side away from the explosion-proof valve 121. This helps to concentrate heat on one side of the individual battery, reducing the thermal impact on the area near the explosion-proof valve 121 and thus reducing the risk of accidental triggering of the explosion-proof valve 121. Secondly, the current path is optimized. By placing the positive tab 24 and the negative tab 25 on the same side, the current path can be simplified, reducing resistance loss in current transmission and improving the overall efficiency of the individual battery. In addition, this layout helps to maintain the structural symmetry of the individual battery, balance the internal stress distribution, and improve the mechanical stability of the individual battery. Finally, since both the positive tab 24 and the negative tab 25 are far from the explosion-proof valve 121, the high temperature on the tab side will not directly affect the operation of the explosion-proof valve 121, allowing the explosion-proof valve 121 to open normally in the event of thermal runaway and quickly release the heat inside the individual battery.

[0050] Understandably, the inner core 20 is composed of multiple layers of positive electrode sheets 21, separator 22, and negative electrode sheets 23 stacked together to form a compact cell structure. The material selection and coating process of the positive electrode sheets 21 and negative electrode sheets 23 improve the energy density and cycle life of the single cell. The separator 22 uses a high heat-resistant material, which can effectively isolate the positive and negative electrodes and prevent short circuits even under high temperature conditions.

[0051] In some embodiments, please refer to Figures 4 and 5. Figure 5 is a schematic diagram showing the positional relationship of the positive electrode 21, negative electrode 23, and separator 22 provided in this embodiment. The outline size of the positive electrode 21 is smaller than that of the negative electrode 23, and the outline size of the negative electrode 23 is smaller than that of the separator 22. This size difference helps prevent internal short circuits in a single cell. Since the separator 22 has the largest outline size, it can completely cover the positive electrode 21 and the negative electrode 23, ensuring effective isolation between the positive and negative electrodes and reducing the risk of short circuits. Even if the battery is subjected to external impact or internal expansion, the edge margin of the separator 22 can provide additional protection. The smaller outline size of the positive electrode 21 compared to the negative electrode 23 optimizes the current distribution. The larger size of the negative electrode 23 allows the negative electrode to fully contact the electrolyte during battery charging and discharging, improving the charging and discharging efficiency and consistency of the battery. This structure can also improve the safety and stability of a single cell. Because separator 22 is the largest, it forms a protective barrier inside the individual cell, providing additional safety in case of overheating or overcharging. This size difference helps simplify the manufacturing process of the individual cells. Due to the different dimensions of the materials, alignment and assembly are easier during manufacturing, improving production efficiency and reducing manufacturing costs.

[0052] In some embodiments, an explosion-proof valve 121 is provided on the first base plate 12. Specifically, an explosion vent is formed on the first base plate 12, and the explosion-proof valve 121 is installed on the explosion vent, with the size of the explosion-proof valve 121 adapted to the size of the explosion vent. The size of the explosion-proof valve 121 is proportional to the size of the exhaust channel 30, that is, the size of the explosion vent is proportional to the size of the exhaust channel 30. This means that the size of the explosion-proof valve 121 is adjusted according to the size of the exhaust channel 30. Specifically, the proportionality between the size of the explosion-proof valve 121 and the size of the exhaust channel 30 allows the explosion-proof valve 121 to effectively release the pressure and heat inside the battery in the event of thermal runaway, reducing the risk of heat accumulation. A larger explosion-proof valve 121 and exhaust channel 30 can expel gas more quickly, reducing the possibility of excessive internal battery pressure leading to explosion or other dangerous situations. Furthermore, the sizes of the explosion-proof valve 121 and exhaust channel 30 can be adjusted according to the specific battery size and application requirements to further optimize the overall performance and safety of the battery. This embodiment optimizes the size of the exhaust channel 30, enabling the battery to better manage heat under high temperature or overload conditions, extending battery life and improving its reliability. This battery structure enhances thermal management performance and safety, allowing the battery to operate safely under various operating conditions.

[0053] Among them, the size of the explosion-proof valve 121 refers to the pressure relief area of ​​the explosion-proof valve 121, the size of the exhaust channel 30 refers to the equivalent flow cross-sectional area of ​​the exhaust channel 30, and the size of the explosion relief port refers to the area of ​​the explosion relief port.

[0054] In some embodiments, the size of the venting channel 30 is inversely proportional to the size of the second distance L2, meaning that as the second distance L2 decreases, the size of the venting channel 30 increases. Specifically, by reducing the second distance L2, the edge of the separator 22 near the explosion-proof valve 121 is closer to the negative electrode 23, and thus farther from the first base plate 12, providing more space for the venting channel 30 and increasing its size. This helps to more effectively expel internal gases and heat in the event of thermal runaway, reducing the risk of excessive internal pressure. This inverse relationship allows for flexible adjustments to the battery's internal structure while optimizing battery safety. By reducing the size of the separator 22 covering the negative electrode 23 near the explosion-proof valve 121 (i.e., the second distance L2), more space is available for the venting channel 30, thereby improving the venting efficiency of the explosion-proof valve 121. Furthermore, this arrangement also improves the battery's thermal management performance. A larger venting channel 30 can release heat more quickly, helping the battery maintain a stable temperature under high temperature or overload conditions, thereby extending battery life and improving its reliability. In other words, by making the size of the exhaust channel 30 inversely proportional to the second distance L2, the safety and thermal management capabilities of the battery can be significantly improved without affecting battery performance.

[0055] In some embodiments, the first distance L1 is greater than or equal to 6 mm and less than or equal to 10 mm, and the second distance L2 is greater than or equal to 1 mm and less than or equal to 4 mm. Specifically, the first distance L1 can be any value or a range between any two of the following: 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, and 10 mm. The second distance L2 can be any value or a range between any two of the following: 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, and 4 mm. When the first distance L1 is in the range of 6 mm to 10 mm, the larger the first distance L1, the larger the size of the negative electrode plate 23 covered by the diaphragm 22 on the side away from the explosion-proof valve 121. In the case that the temperature on the side away from the explosion-proof valve 121 is high and the diaphragm 22 shrinks due to heat, the size of the diaphragm 22 covering the negative electrode plate 23 is still optimal, preventing the negative electrode tab 25 from directly contacting the negative electrode plate 23, thereby reducing the risk of short circuit. The smaller the first distance L1, the smaller the size of the negative electrode plate 23 covered by the diaphragm 22 on the side away from the explosion-proof valve 121. Therefore, even if the diaphragm 22 shrinks due to high temperature on the side away from the explosion-proof valve 121, the size of the diaphragm 22 covering the negative electrode plate 23 remains within a reasonable range. The diaphragm 22 can still effectively cover the negative electrode plate 23, preventing direct contact between the negative electrode tab 25 and the negative electrode plate 23, thus reducing the risk of short circuits. The second distance L2 is in the range of 1mm to 4mm. The larger the second distance L2, the larger the size of the negative electrode plate 23 covered by the diaphragm 22 on the side closer to the explosion-proof valve 121. Consequently, the exhaust channel 30 is smaller, and the size of the explosion-proof valve 121 is correspondingly smaller, thus improving pressure management performance. The smaller the second distance L2, the smaller the size of the negative electrode plate 23 covering the side of the diaphragm 22 near the explosion-proof valve 121, and the larger the exhaust channel 30 will be. The distance that the explosive object travels through the exhaust channel 30 to reach the explosion-proof valve 121 will be longer, so the explosion-proof valve 121 can be set to a larger size.

[0056] In related technologies, the distance between the edges of the electrode and the edges of the separator 22 is consistent and ranges from 3 to 5 mm. In contrast, this embodiment offers several advantages by setting the first distance L1 to be greater than or equal to 6 mm and less than or equal to 10 mm, and the second distance L2 to be greater than or equal to 1 mm and less than or equal to 4 mm. Increasing the size of the separator 22 covering the negative electrode 23 on the side furthest from the explosion-proof valve 121 (i.e., the first distance L1) ensures that the separator 22 can still effectively cover the corresponding negative electrode 23 during thermal shrinkage. Increasing the first distance L1 provides a larger buffer space inside the individual battery cell, especially under excessive pressure, helping to prevent damage or explosion of the individual battery cell, thereby improving overall safety. Furthermore, a larger first distance L1 facilitates more effective heat dissipation, reducing heat accumulation inside the individual battery cell, lowering the risk of overheating, and improving the battery's thermal management performance. The size of the negative electrode plate 23 covered by the diaphragm 22 near the explosion-proof valve 121 is reduced (i.e., the second distance L2), thereby increasing the distance between the first base plate 12 and the inner core 20, so that the exhaust channel 30 has more space so that the explosion-proof valve 121 can open in time during thermal runaway.

[0057] In some embodiments, the third distance L3 is greater than or equal to 8 mm and less than or equal to 12 mm, and the fourth distance L4 is greater than or equal to 4 mm and less than or equal to 6 mm. Specifically, the third distance L3 can be any value among 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, 10.5 mm, 11 mm, 11.5 mm, and 12 mm, or a range between any two values. The fourth distance L4 can be any value among 4 mm, 4.5 mm, 5 mm, 5.5 mm, and 6 mm, or a range between any two values. When the third distance L3 is in the range of 8 mm to 12 mm, the larger the third distance L3, the larger the size of the positive electrode plate 21 covered by the diaphragm 22 on the side away from the explosion-proof valve 121. In the case that the temperature on the side away from the explosion-proof valve 121 is high and the diaphragm 22 shrinks due to heat, the size of the diaphragm 22 covering the positive electrode plate 21 is still better, preventing the positive electrode tab 24 from directly contacting the positive electrode plate 21, thereby reducing the risk of short circuit. The smaller the third distance L3, the smaller the size of the positive electrode plate 21 covered by the diaphragm 22 on the side away from the explosion-proof valve 121. Therefore, even if the temperature on the side away from the explosion-proof valve 121 is high, causing the diaphragm 22 to shrink due to heat, the size of the diaphragm 22 covering the positive electrode plate 21 remains within a reasonable range. The diaphragm 22 can still effectively cover the positive electrode plate 21, preventing direct contact between the negative electrode tab 25 and the negative electrode plate 23, thus reducing the risk of short circuit. The fourth distance L4 is in the range of 4mm to 6mm. The larger the fourth distance L4, the larger the size of the positive electrode plate 21 covered by the diaphragm 22 on the side closer to the explosion-proof valve 121. Consequently, the exhaust channel 30 is smaller, and the size of the explosion-proof valve 121 is increased to improve pressure management performance. When the fourth distance L4 is smaller, the size of the positive electrode plate 21 covered by the diaphragm 22 on the side closer to the explosion-proof valve 121 is smaller, and the exhaust channel 30 is correspondingly smaller. The explosion-proof valve 121 can be set smaller because a larger exhaust channel 30 already provides sufficient pressure release capacity.

[0058] In related technologies, the distance between the edges of the electrode and the edges of the separator 22 is consistent and ranges from 3 to 5 mm. In contrast, this embodiment offers several advantages by setting the third distance L3 to be greater than or equal to 8 mm and less than or equal to 12 mm, and the fourth distance L4 to be greater than or equal to 4 mm and less than or equal to 6 mm. Increasing the size of the separator 22 covering the positive electrode 21 on the side furthest from the explosion-proof valve 121 (i.e., the third distance L3) ensures that the separator 22 can still effectively cover the corresponding positive electrode 21 during thermal shrinkage. Increasing the third distance L3 provides a larger buffer space inside the individual cell, especially under excessive pressure, helping to prevent damage or explosion of the individual cell, thereby improving overall safety. Furthermore, a larger third distance L3 facilitates more effective heat dissipation, reducing heat accumulation inside the individual cell, lowering the risk of overheating, and improving the battery's thermal management performance. The size of the positive electrode plate 21 covered by the diaphragm 22 near the explosion-proof valve 121 is reduced (i.e., the fourth distance L4), thereby increasing the distance between the first base plate 12 and the inner core 20, so that the exhaust channel 30 has more space so that the explosion-proof valve 121 can open in time during thermal runaway.

[0059] In some embodiments, the difference between the first distance L1 and the second distance L2, L1-L2, is greater than or equal to 2 mm and less than or equal to 6 mm. The difference between the third distance L3 and the fourth distance L4, L3-L4, is greater than or equal to 3 mm and less than or equal to 7 mm. Specifically, the difference between the first distance L1 and the second distance L2, L1-L2, can be any value among 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, and 6 mm, or a range between any two values. The difference between the first distance L1 and the second distance L2, L1-L2, defines the size requirements for the negative electrode sheets 23 covering both ends of the separator 22. The difference between the third distance L3 and the fourth distance L4, L3-L4, can be any value among 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, and 7 mm, or a range between any two values. The difference between the third distance L3 and the fourth distance L4, L3-L4, defines the size requirements for the positive electrode sheet 21 covered at both ends of the separator 22. Controlling the difference between the first distance L1 and the second distance L2, L1-L2, and the difference between the third distance L3 and the fourth distance L4, L3-L4, improves battery safety and other performance. By controlling the difference between the first distance L1 and the second distance L2, L1-L2 ensures that the edge of the negative electrode sheet 23 is fully covered by the separator 22 and increases the space of the venting channel 30, thereby reducing the risk of electrode material exposure, lowering the possibility of short circuits, and providing sufficient pressure release capability. By controlling the difference between the third distance L3 and the fourth distance L4, L3-L4 ensures that the edge of the positive electrode sheet 21 is fully covered by the separator 22 and increases the space of the venting channel 30, preventing direct contact between electrode materials, thereby improving battery safety and providing sufficient pressure release capability.

[0060] Accordingly, the battery pack provided in this application includes the single cell of any of the above embodiments. Therefore, the battery pack can have all the technical features and beneficial effects of the single cell described above, which will not be repeated here.

[0061] Accordingly, the energy storage system provided in this application includes a single battery cell of any of the above embodiments, or a battery pack of the above embodiments, and thus can have all the technical features and technical effects of the above single battery cell or battery pack, which will not be repeated here.

[0062] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0063] The single-cell battery, battery pack, and energy storage system provided in the embodiments of this application have been described in detail above, and specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

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