Cylindrical battery cell and electric equipment

Abstract

The invention provides a cylindrical battery cell and electric equipment, the cylindrical battery cell comprises an electrode assembly with a winding structure and a central needle, and the electrode assembly is provided with a central hole. The center needle is arranged in the center hole, the center needle is of a tubular structure, and the center needle is provided with a first end face and a second end face which are opposite in the axial direction of the center needle. The center needle is provided with through holes and blind holes, the through holes penetrate through the first end face and the second end face in the axial direction of the center needle, the blind holes penetrate through the first end face and do not penetrate through the second end face, and the through holes and the blind holes are formed in the circumferential direction of the center needle at intervals. The supporting strength of the center needle can be high, the risk that the inner ring of the electrode assembly sinks inwards is reduced, the blind hole and the through hole can contain gas, an internal gas chamber of the cylindrical battery cell can be balanced, the through hole can be used for circulation of internal gas and electrolyte, the pressure relief speed of the cylindrical battery cell is high, and the service life of the cylindrical battery cell is prolonged. The infiltration effect of the cylindrical battery cell is better, and the cylindrical battery cell has relatively high safety and relatively long cycle life.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a cylindrical battery cell and an electrical device thereof. Background Technology

[0002] Currently, with the rapid development of new energy technologies, battery cells have been widely used in electronic devices, electric vehicles, electric two-wheelers, power tools, and other fields. As the application of battery cells becomes more widespread, higher requirements are being placed on their safety and cycle life. Summary of the Invention

[0003] This application provides a cylindrical battery cell and an electrical device that can improve the safety and cycle life of the cylindrical battery cell.

[0004] In a first aspect, this application provides a cylindrical battery cell, comprising an electrode assembly with a wound structure and a center pin, the electrode assembly having a central hole. The center pin is disposed within the central hole and has a tubular structure, having opposing first and second end faces along its axial direction. The center pin is provided with a through hole and a blind hole, the through hole penetrating the first and second end faces along its axial direction, and the blind hole penetrating the first end face but not the second end face, the through hole and blind hole being spaced apart circumferentially around the center pin.

[0005] In the above technical solutions, if only through holes are provided on the center pin, it will affect the support strength of the center pin. The center pin cannot resist the expansion force of the electrode assembly during cycling, causing the stress concentration points of the electrode assembly to deform due to compression. The risk of inward sinking of the inner ring of the electrode assembly is relatively high, affecting the safety and cycle life of the cylindrical cell. If only blind holes are provided on the center pin, the gas and electrolyte inside the cylindrical cell can only flow through the inner hole of the tubular structure of the center pin. The slow gas flow results in a slow depressurization rate of the cylindrical cell, affecting the safety of the cylindrical cell. The slow electrolyte flow results in poor wetting effect of the cylindrical cell, affecting the cycle life of the cylindrical cell. This application provides a center pin with... The device is equipped with through holes and blind holes. Along the axial direction of the center pin, the through holes penetrate the first and second end faces, while the blind holes penetrate the first end face but not the second end face. The through holes and blind holes are spaced apart around the circumference of the center pin. This arrangement not only provides higher support strength for the center pin, reducing the risk of indentation of the inner ring of the electrode assembly and improving the safety and cycle life of the cylindrical cell, but also allows the blind holes and through holes to accommodate gas, which helps balance the internal gas chambers of the cylindrical cell. The through holes can also be used for the flow of internal gas, resulting in a faster depressurization speed and improved safety of the cylindrical cell. Furthermore, the through holes can also be used for the flow of internal electrolyte, resulting in better wetting of the cylindrical cell and improving its cycle life.

[0006] In some embodiments of this application, along the axial direction of the center pin, the height of the center pin is H0, the height of the blind hole is H1, and 50%≤H1 / H0≤80%.

[0007] In the above technical solutions, when H1 / H0 is greater than or equal to 50%, the accommodating space of the blind hole is not too small, allowing for more gas to be accommodated, reducing the internal pressure of the cylindrical cell, thereby reducing the pressure of the through-hole venting, reducing the possibility of the pressure relief valve of the cylindrical cell opening prematurely, and thus improving the cycle life of the cylindrical cell; and / or, it ensures that the height of the center pin is not too large, reducing the risk of the center pin exceeding the electrode assembly in the winding axis direction, which is beneficial to reducing the overall length of the electrode assembly and the center pin in the winding axis direction, and improving the energy density of the cylindrical cell; when H1 / H0 is small... When the percentage is 50% or equal to 80%, the volume ratio of the blind hole in the center pin is not too large, which can improve the support strength of the center pin, reduce the risk of indentation of the inner ring of the electrode assembly, and improve the safety and cycle life of the cylindrical cell; and / or, it can ensure that the height of the center pin is not too small, so that the support area of ​​the center pin for the electrode assembly is larger and the support strength is higher, which can reduce the risk of indentation of the inner ring of the electrode assembly and improve the safety and cycle life of the cylindrical cell; therefore, when 50%≤H1 / H0≤80%, the cylindrical cell has a higher cycle life, energy density and safety.

[0008] In some embodiments of this application, the central pin is provided with multiple through holes and multiple blind holes, with the multiple through holes and multiple blind holes spaced apart along the circumference of the central pin.

[0009] In the above technical solution, by providing multiple through holes and multiple blind holes in the center pin, the center pin has more space to accommodate gas, which further helps to balance the internal gas chambers of the cylindrical cell. The multiple through holes allow for the flow of internal gas, resulting in faster pressure relief and improved safety. The multiple through holes also allow for the flow of internal electrolyte, leading to better wetting and increased cycle life. Furthermore, by distributing the multiple through holes and blind holes at intervals along the circumference of the center pin, the distribution of these holes and holes is more uniform. This results in a more even distribution of the supporting force on the electrode assembly, reducing stress concentration points and minimizing the risk of inner ring sagging in the electrode assembly, thus improving the safety and cycle life of the cylindrical cell.

[0010] In some embodiments of this application, through holes and blind holes are alternately arranged along the circumference of the center pin.

[0011] In the above technical solution, by alternating through holes and blind holes along the circumference of the center pin, the distribution of through holes and blind holes in the circumference of the center pin can be made more uniform, thereby making the support force of the center pin on the electrode assembly more uniform. This can further reduce the occurrence of stress concentration points in the electrode assembly, which is beneficial to further reduce the risk of indentation of the inner ring of the electrode assembly, and further improve the safety and cycle life of the cylindrical cell.

[0012] In some embodiments of this application, the distance from each through hole to the axis of the center pin is equal, the distance from each blind hole to the axis of the center pin is equal, and the distance from the through hole to the axis of the center pin is less than the distance from the blind hole to the axis of the center pin.

[0013] In the above technical solution, by making the distances from each through hole to the axis of the center pin equal, and the distances from each blind hole to the axis of the center pin equal, the force on the center pin and the reverse supporting force on the electrode assembly are more uniform when the electrode assembly expands. This further reduces the occurrence of stress concentration points on the electrode assembly, which helps to further reduce the risk of inward sagging of the inner ring of the electrode assembly, and further improves the safety and cycle life of the cylindrical cell. Since the supporting force of the part of the center pin with blind holes is stronger than that of the part with through holes, by making the distance from the through hole to the axis of the center pin smaller than the distance from the blind hole to the axis of the center pin (i.e., the blind hole is closer to the outer surface of the center pin), the part of the center pin with blind holes is stressed before the part with through holes. The supporting effect of the center pin is better, which helps to further reduce the risk of inward sagging of the inner ring of the electrode assembly, and further improves the safety and cycle life of the cylindrical cell.

[0014] In some embodiments of this application, along the circumference of the center pin, the distance from any through hole to the blind holes located on both sides of the through hole is equal.

[0015] In the above technical solution, by making the distance from any through hole to the blind holes located on both sides of the through hole equal along the circumference of the center pin, the through holes and blind holes can be further evenly distributed in the circumference of the center pin, thereby making the supporting force of the center pin on the electrode assembly evenly distributed, which can further reduce the occurrence of stress concentration points in the electrode assembly, and help to further reduce the risk of inward sinking of the inner ring of the electrode assembly, and further improve the safety and cycle life of the cylindrical cell.

[0016] In some embodiments of this application, the sum of the cross-sectional areas of the multiple through holes is S1, the sum of the cross-sectional areas of the multiple blind holes is S2, and 0.8≤S2 / S1≤1.2.

[0017] In the above technical solution, when S2 / S1 is greater than or equal to 0.8, the sum of the cross-sectional areas of the multiple blind holes will not be too small, thus ensuring that the sum of the volumes of the multiple blind holes is not too small. This allows the multiple blind holes to accommodate more gas, reducing the internal pressure of the cylindrical cell, thereby reducing the pressure of the through-hole exhaust and reducing the possibility of premature opening of the pressure relief valve of the cylindrical cell, which is beneficial to improving the cycle life of the cylindrical cell; and / or, the cross-sectional areas of the multiple through holes will not be too large, thus ensuring that the sum of the volumes of the multiple through holes is not too large, which is beneficial to improving the support strength of the center pin, reducing the risk of inward sinking of the inner ring of the electrode assembly, and improving the safety and cycle life of the cylindrical cell; when S2 / When S1 is less than or equal to 1.2, the sum of the cross-sectional areas of the multiple blind holes will not be too large, and thus the sum of the volumes of the multiple blind holes will not be too large. This is beneficial to improving the support strength of the center pin, reducing the risk of indentation of the inner ring of the electrode assembly, and improving the safety and cycle life of the cylindrical cell. And / or, the cross-sectional areas of the multiple through holes will not be too small, and thus the sum of the volumes of the multiple through holes will not be too small. This allows the multiple through holes to accommodate more gas, reducing the internal pressure of the cylindrical cell, which is beneficial to improving the cycle life of the cylindrical cell. It also allows the multiple through holes to accommodate more electrolyte, which can improve the wetting effect of the cylindrical cell, which is beneficial to improving the cycle life of the cylindrical cell. Furthermore, it allows the cylindrical cell to depressurize faster, improving the safety of the cylindrical cell. Therefore, when 0.8≤S2 / S1≤1.2, the cylindrical cell has high safety and cycle life.

[0018] In some embodiments of this application, the cross-sectional area of ​​the center pin is S0, the sum of the cross-sectional areas of the multiple through holes is S1, and 10%≤S1 / S0≤40%; the sum of the cross-sectional areas of the multiple blind holes is S2, and 10%≤S2 / S0≤30%.

[0019] In the above technical solution, when S1 / S0 is greater than or equal to 10%, the cross-sectional area of ​​the multiple through holes is not too small, thus ensuring that the total volume of the multiple through holes is not too small. This allows the multiple through holes to accommodate more gas, reducing the internal pressure of the cylindrical battery cell and improving its cycle life. It also allows the multiple through holes to accommodate more electrolyte, improving the wetting effect of the cylindrical battery cell and further enhancing its cycle life. Furthermore, it allows for faster pressure relief, improving the safety of the cylindrical battery cell. And / or, the cross-sectional area of ​​the center pin is not too large. With the outer diameter of the center pin remaining constant, the inner diameter of the center pin is not too small, facilitating gas flow through the inner hole of the center pin and resulting in faster pressure relief of the cylindrical battery cell, thus improving its safety. When S1 / When S0 is less than or equal to 40%, the cross-sectional area of ​​multiple through holes will not be too large, and thus the total volume of multiple through holes will not be too large. This is beneficial to improving the support strength of the center pin, reducing the risk of indentation of the inner ring of the electrode assembly, and improving the safety and cycle life of the cylindrical cell. And / or, the cross-sectional area of ​​the center pin will not be too small, which can improve the support strength of the center pin, reduce the risk of indentation of the inner ring of the electrode assembly, and improve the safety and cycle life of the cylindrical cell. Therefore, when 10%≤S1 / S0≤40%, the cylindrical cell has high safety and cycle life.

[0020] When S2 / S0 is greater than or equal to 10%, the sum of the cross-sectional areas of multiple blind holes will not be too small, thus ensuring that the sum of the volumes of multiple blind holes will not be too small. This allows the multiple blind holes to accommodate more gas, reducing the internal pressure of the cylindrical cell, thereby reducing the pressure of the through-hole venting and decreasing the possibility of premature opening of the pressure relief valve of the cylindrical cell, which is beneficial to improving the cycle life of the cylindrical cell; and / or, the cross-sectional area of ​​the center pin will not be too large. With the outer diameter of the center pin remaining unchanged, the inner diameter of the center pin will not be too small, facilitating the flow of gas through the inner hole of the center pin, resulting in a faster pressure relief speed of the cylindrical cell and improving the safety of the cell; when S2 / When S0 is less than or equal to 30%, the sum of the cross-sectional areas of multiple blind holes will not be too large, and thus the sum of the volumes of multiple blind holes will not be too large. This is beneficial to improving the support strength of the center pin, reducing the risk of indentation of the inner ring of the electrode assembly, and improving the safety and cycle life of the cylindrical cell. And / or, the cross-sectional area of ​​the center pin will not be too small, which can improve the support strength of the center pin, reduce the risk of indentation of the inner ring of the electrode assembly, and improve the safety and cycle life of the cylindrical cell. Therefore, when 10%≤S2 / S0≤30%, the cylindrical cell has high safety and cycle life.

[0021] In some embodiments of this application, the distance between any adjacent through hole and blind hole is G, where 0.5mm≤G≤1mm.

[0022] In the above technical solutions, when G is greater than or equal to 0.5 mm, the distribution density of through holes and blind holes on the center pin is not too large, reducing the space occupied by through holes and blind holes, which is beneficial to improving the support strength of the center pin, reducing the risk of indentation of the inner ring of the electrode assembly, improving the safety and cycle life of the cylindrical cell, and reducing the possibility of partial fracture between through holes and blind holes under stress. When G is less than or equal to 1 mm, the distribution density of through holes and blind holes on the center pin is not too small, the center pin has more through holes and blind holes to accommodate gas, which can reduce the internal pressure of the cylindrical cell, which is beneficial to improving the cycle life of the cylindrical cell. The center pin has more through holes to accommodate electrolyte, which can improve the wetting effect of the cylindrical cell, which is beneficial to improving the cycle life of the cylindrical cell, and can make the pressure relief speed of the cylindrical cell faster, improving the safety of the cell. It can also reduce the possibility of gas bypassing blind holes and then escaping, which is beneficial to reducing gas flow resistance, thereby reducing the possibility of indentation. Reducing the venting pressure in the orifice decreases the likelihood of premature opening of the pressure relief valve, which is beneficial for improving the cycle life of cylindrical cells. Therefore, when 0.5mm≤G≤1mm, it not only helps to improve the support strength of the center pin and reduce the risk of inward collapse of the inner ring of the electrode assembly, thus improving the safety and cycle life of the cylindrical cell, but also reduces the possibility of partial stress fracture between the through-hole and blind-hole. Furthermore, it allows the center pin to have more through-holes and blind-holes to accommodate gas, reducing the internal pressure of the cylindrical cell and improving its cycle life. More through-holes in the center pin to accommodate electrolyte improve the wetting effect of the cylindrical cell, further enhancing its cycle life. It also allows for faster pressure relief, improving cell safety, and reduces the possibility of gas bypassing the blind-hole for re-exit, thus reducing gas flow resistance and consequently reducing the venting pressure in the through-hole, decreasing the likelihood of premature opening of the pressure relief valve, and ultimately improving the cycle life of the cylindrical cell.

[0023] In some embodiments of this application, the wall thickness of the center pin is T along the radial direction of the center pin, and the diameter of the through hole is D1, where 0.1≤D1 / T≤0.3.

[0024] In the above technical solution, when D1 / T is greater than or equal to 0.1, the diameter of the through-hole is not too small, thus ensuring that the volume of the through-hole is not too small. This allows the through-hole to accommodate more gas, reducing the internal pressure of the cylindrical cell and improving its cycle life. It also allows the through-hole to accommodate more electrolyte, improving the wetting effect of the cylindrical cell and further enhancing its cycle life. Furthermore, it facilitates the flow of gas and electrolyte, reducing the likelihood of blockage and allowing for faster pressure relief, thus improving cell safety. And / or, the wall thickness of the center pin is not too large. With the outer diameter of the center pin remaining constant, the inner diameter of the center pin is not too small, facilitating gas flow through the inner hole of the center pin and resulting in faster pressure relief, further improving the safety of the cylindrical cell and facilitating electrolyte flow. The flow through the inner hole of the center pin improves the wetting effect of the cylindrical cell, thus increasing its cycle life. When D1 / T is less than or equal to 0.3, the diameter of the through hole is not too large, which helps to improve the support strength of the center pin, reduces the risk of indentation of the inner ring of the electrode assembly, and improves the safety and cycle life of the cylindrical cell. Furthermore, in the early stage of thermal runaway of the cylindrical cell, gas will not be directly and rapidly discharged, which reduces the possibility of electrolyte splashing caused by a sudden drop in internal pressure. And / or, the wall thickness of the center pin is not too small, which can improve the support strength of the center pin, reduce the risk of indentation of the inner ring of the electrode assembly, and improve the safety and cycle life of the cylindrical cell. Therefore, when 0.1≤D1 / T≤0.3, the cylindrical cell has high safety and cycle life.

[0025] In some embodiments of this application, the diameter of the blind hole is D2, and 0.05≤D2 / T≤0.2.

[0026] In the above technical solution, when D2 / T is greater than or equal to 0.05, the diameter of the blind hole is not too small, which in turn ensures that the volume of the blind hole is not too small. This allows the blind hole to hold more gas, reducing the internal pressure of the cylindrical cell, thereby reducing the pressure of the through-hole venting and decreasing the possibility of the cell's pressure relief valve opening prematurely, which is beneficial to improving the cycle life of the cylindrical cell. And / or, the wall thickness of the center pin is not too large. With the outer diameter of the center pin remaining constant, the inner diameter of the center pin is not too small, facilitating gas flow through the inner hole of the center pin and making the pressure relief speed of the cylindrical cell faster. Faster speed improves cell safety; when D2 / T is less than or equal to 0.2, the diameter of the blind hole will not be too large, which helps to improve the support strength of the center pin, reduce the risk of the inner ring of the electrode assembly sinking, and improve the safety and cycle life of the cylindrical cell; and / or, the wall thickness of the center pin will not be too small, which can improve the support strength of the center pin, reduce the risk of the inner ring of the electrode assembly sinking, and improve the safety and cycle life of the cylindrical cell; therefore, when 0.05≤D2 / T≤0.2, the cylindrical cell has high safety and cycle life.

[0027] In some embodiments of this application, the electrode assembly includes a negative electrode sheet, which includes a negative current collector and a negative active material layer. The negative active material layer is disposed on at least one side of the negative current collector along its thickness direction. The negative active material layer includes a silicon-based material. The coefficient of thermal expansion of the negative electrode sheet is k, the number of through holes is N1, the number of blind holes is N2, 0.1≤k≤0.5, 10%≤N2 / N1≤40%; or, 0.5<k≤1.0, 70%≤N2 / N1≤95%.

[0028] In the above technical solutions, when 0.1≤k≤0.5, the expansion coefficient of the negative electrode is small, and the pressure acting on the center pin during the electrode assembly cycle is small, corresponding to 10%≤N2 / N1≤40%, meaning that the number of through holes is greater than the number of blind holes. This allows the center pin to have more space to accommodate gas while maintaining a certain supporting strength, which can reduce the internal pressure of the cylindrical cell, improve the cycle life of the cylindrical cell, and enable the pressure relief speed of the cylindrical cell to be faster, thus improving the safety of the cell. When 0.5<k≤1.0, the expansion coefficient of the negative electrode is large, and the pressure acting on the center pin during the electrode assembly cycle is large, corresponding to 70%≤N2 / N1≤95%. This means that the number of blind holes is greater than the number of through holes, resulting in higher supporting strength of the center pin, reducing the risk of inward collapse of the inner ring of the electrode assembly, and thus improving the safety and cycle life of the cylindrical cell.

[0029] In some embodiments of this application, the electrode assembly includes a main body, a positive electrode tab, and a negative electrode tab. The positive electrode tab is disposed at a first end of the main body along the winding axis of the electrode assembly, and the negative electrode tab is disposed at a second end of the main body along the winding axis. The first end and the second end are the two ends of the electrode assembly along the winding axis, respectively. The first end face is closer to the positive electrode tab than the second end face.

[0030] In the above technical solution, since more heat is generated at the positive electrode tab, more gas is produced. By making the first end face closer to the positive electrode tab than the second end face, that is, the opening of the blind hole faces the positive electrode tab, the gas generated near the positive electrode tab can quickly enter the blind hole, which helps to reduce the unevenness of the internal pressure of the cylindrical cell and improve the cycle life of the cylindrical cell.

[0031] In some embodiments of this application, the outer diameter of the central pin is 2mm-5mm, the inner diameter is 1mm-3mm, and the wall thickness is 0.5mm-1mm along the radial direction of the central pin.

[0032] In the above technical solution, when the outer diameter of the center pin is greater than or equal to 2mm, it facilitates the fit between the center pin and the outer circumferential surface of the electrode assembly when it expands, allowing the center pin to provide support for the electrode assembly. This reduces the risk of indentation of the inner ring of the electrode assembly, thus improving the safety and cycle life of the cylindrical battery cell. When the outer diameter of the center pin is less than or equal to 5mm, it facilitates the assembly of the center pin and the electrode assembly, thus improving the manufacturing efficiency of the battery cell. Therefore, when the outer diameter of the center pin is 2mm-5mm, it not only facilitates the fit between the center pin and the outer circumferential surface of the electrode assembly when it expands, allowing the center pin to provide support for the electrode assembly and reducing the risk of indentation of the inner ring of the electrode assembly, thus improving the safety and cycle life of the cylindrical battery cell, but also facilitates the assembly of the center pin and the electrode assembly, thus improving the manufacturing efficiency of the battery cell.

[0033] When the inner diameter of the center pin is greater than or equal to 1 mm, the inner volume of the center pin is not too small, facilitating gas flow through the inner hole of the center pin, resulting in faster pressure relief of the cylindrical cell and improved safety. It also facilitates electrolyte flow through the inner hole of the center pin, leading to better wetting and increased cycle life. When the inner diameter of the center pin is less than or equal to 3 mm, the space occupied by the inner hole is reduced, which is beneficial for increasing the energy density of the cell. Therefore, when the inner diameter of the center pin is between 1 mm and 3 mm, it facilitates gas flow through the inner hole of the center pin, resulting in faster pressure relief and improved safety of the cylindrical cell; it also facilitates electrolyte flow through the inner hole of the center pin, leading to better wetting and increased cycle life; and it also reduces the space occupied by the inner hole, which is beneficial for increasing the energy density of the cell.

[0034] When the wall thickness of the center pin is greater than or equal to 0.5 mm, it prevents the wall thickness from becoming too small, thus improving the support strength of the center pin and reducing the risk of indentation of the inner ring of the electrode assembly. This is beneficial for improving the safety and cycle life of the cylindrical cell. When the wall thickness of the center pin is less than or equal to 1 mm, it prevents the wall thickness from becoming too large. With the outer diameter of the center pin remaining constant, the inner diameter of the center pin will not be too small, facilitating gas flow through the inner hole of the center pin. This allows for faster pressure relief of the cylindrical cell, improving its safety and facilitating electrolyte flow through the center pin. The flow through the inner hole allows for better wetting of the cylindrical battery cell, thus improving its cycle life. Therefore, when the wall thickness of the center pin is 0.5mm-1mm, it not only improves the support strength of the center pin and reduces the risk of indentation of the inner ring of the electrode assembly, which is beneficial to improving the safety and cycle life of the cylindrical battery cell, but also facilitates the flow of gas through the inner hole of the center pin, resulting in faster depressurization of the cylindrical battery cell and improving its safety, and facilitates the flow of electrolyte through the inner hole of the center pin, resulting in better wetting of the cylindrical battery cell and improving its cycle life.

[0035] Secondly, this application provides an electrical device including a cylindrical battery cell as described above, the cylindrical battery cell being used to provide electrical energy. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings.

[0037] Figure 1 Cross-sectional views of cylindrical battery cells provided in some embodiments of this application; Figure 2 A schematic diagram of the structure of a cylindrical battery cell from one perspective, provided in some embodiments of this application; Figure 3 A schematic diagram of the structure of the center pin of a cylindrical battery cell provided in some embodiments of this application; Figure 4 for Figure 3 The sectional view along AA with the center pin in the middle; Figure 5 for Figure 3 The sectional view along BB with the center pin in the middle; Figure 6 This is a schematic diagram of the negative electrode sheet of a cylindrical battery cell provided in some embodiments of this application; Figure 7 Scanning images of the electrode assembly of a cylindrical battery cell after 600 charge-discharge cycles, as provided in some embodiments of this application.

[0038] Icons: 10-Cylindrical cell; 100-Electrode assembly; 100a-Main body; 101-Center hole; 110-Positive electrode; 120-Negative electrode; 121-Negative current collector; 122-Negative active material layer; 130-Separator; 140-Positive electrode tab; 150-Negative electrode tab; 200-Outer shell; 210-Electrode post; 300-Center pin; 301-Through hole; 302-Blind hole; 303-Inner hole; 310-First end face; 320-Second end face; 410-First current collector; 420-Second current collector; X-Axis of center pin; Y-Radial direction of center pin; Z-Thickness direction of negative current collector; P-Axis of center pin. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0040] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having" and any variations thereof in the specification, claims and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0041] The terms "first," "second," etc., in the specification, claims, or the accompanying drawings of this application are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0042] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0043] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0044] With the development of the new energy industry, batteries are gradually moving towards higher safety and longer cycle life. During the manufacturing of cylindrical cells, the electrode assembly is wound into shape using a winding needle, and then the needle is pulled out, creating a central hole in the electrode assembly. During the charge-discharge cycle of the cylindrical cell, the electrode assembly expands, compressing the outer casing. Conversely, the electrode assembly receives a reaction force from the casing, causing the inner ring of the electrode assembly to form and become recessed, affecting the safety and cycle life of the cylindrical cell. By setting a central needle in the central hole, the central needle can support the electrode assembly and reduce the possibility of recess. However, the central needle occupies a large space, reducing the space in the central hole for gas containment. This leads to increased internal pressure in the cylindrical cell, affecting its safety and cycle life. Furthermore, the reduced space in the central hole also affects gas flow, slowing down the depressurization rate of the cylindrical cell and impacting its safety.

[0045] To improve the safety and cycle life of cylindrical battery cells, this application provides a cylindrical battery cell including an electrode assembly with a wound structure and a center pin. The electrode assembly has a central hole. The center pin is disposed within the central hole and has a tubular structure. Along the axial direction of the center pin, the center pin has opposing first and second end faces. The center pin is provided with through holes and blind holes. Along the axial direction of the center pin, the through holes penetrate the first and second end faces, and the blind holes penetrate the first end face but not the second end face. The through holes and blind holes are spaced apart circumferentially around the center pin.

[0046] If the center pin only has a through hole, it will affect the support strength of the center pin. The center pin cannot resist the expansion force of the electrode assembly during cycling, causing the stress concentration points of the electrode assembly to deform due to compression. The inner ring of the electrode assembly is at greater risk of indentation, affecting the safety and cycle life of the cylindrical cell. If the center pin only has a blind hole, the gas and electrolyte inside the cylindrical cell can only flow through the inner hole of the tubular structure of the center pin. The slow gas flow results in a slow depressurization rate of the cylindrical cell, affecting its safety. The slow electrolyte flow results in poor wetting effect of the cylindrical cell, affecting its cycle life. This application improves the cylindrical cell by providing a center pin with both through holes and... Blind holes are arranged along the axial direction of the center pin. Through holes penetrate the first and second end faces, while blind holes penetrate the first end face but not the second end face. Through holes and blind holes are spaced apart circumferentially around the center pin. This arrangement not only increases the support strength of the center pin, reducing the risk of indentation of the inner ring of the electrode assembly and improving the safety and cycle life of the cylindrical cell, but also allows the blind holes and through holes to accommodate gas, which helps balance the internal gas chambers of the cylindrical cell. Through holes can also be used for the flow of internal gas, resulting in a faster depressurization speed and improved safety of the cylindrical cell. Through holes can also be used for the flow of internal electrolyte, resulting in better wetting of the cylindrical cell and improved cycle life.

[0047] The cylindrical battery cell provided in this application embodiment can be a secondary battery, such as a lithium-ion battery, sodium-ion battery, or magnesium-ion battery, etc., and this application embodiment is not limited in this respect. The electrochemical device can be cylindrical, flat, cuboid, hexagonal, or other shapes, etc., and this application embodiment is not limited in this respect either.

[0048] This application provides an electrical device that uses cylindrical battery cells as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc.

[0049] See Figure 1 and Figure 2 , Figure 1 Cross-sectional views of cylindrical battery cells provided in some embodiments of this application; Figure 2 This is a schematic diagram of the structure of a cylindrical battery cell provided in some embodiments of this application from one perspective.

[0050] This application provides a cylindrical battery cell 10, which includes an electrode assembly 100 with a wound structure. The electrode assembly 100 includes a positive electrode 110, a negative electrode 120, and a separator 130. The separator 130 is disposed between the positive electrode 110 and the negative electrode 120 to insulate and separate the positive electrode 110 and the negative electrode 120, thereby reducing the risk of short circuit in the cylindrical battery cell 10. The cylindrical battery cell 10 has advantages such as high energy density, good stability, long service life, and high charging rate.

[0051] The cylindrical cell 10 also includes a housing 200 and an electrolyte (not shown in the figure), with the electrode assembly 100 and electrolyte housed within the housing 200. The cylindrical cell 10 primarily operates by the movement of metal ions between the positive electrode 110 and the negative electrode 120. The positive electrode 110 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 portion of the positive current collector without the positive active material layer serves as a positive electrode tab 140, through which electrical energy can be input or output from the positive electrode 110. 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 materials (such as lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, etc.), or lithium manganese oxide, etc. The negative electrode 120 includes a negative current collector 121 and a negative active material layer 122. The negative active material layer 122 is coated on the surface of the negative current collector 121. The portion of the negative current collector 121 without the negative active material layer 122 serves as a negative electrode tab 150, through which electrical energy can be input or output from the negative electrode 120. The material of the negative current collector 121 can be copper, and the negative active material can be carbon or silicon, etc. The separator 130 can be made of polypropylene (PP) or polyethylene (PE), etc. The electrolyte can include organic solvents, lithium salts, etc.

[0052] In some embodiments, the cylindrical cell 10 further includes a center pin 300, and the electrode assembly 100 has a center hole 101, with the center pin 300 disposed within the center hole 101.

[0053] By setting the center pin 300, when the electrode assembly 100 expands, the center pin 300 can support the inner ring of the electrode assembly 100, reducing the possibility of the electrode assembly 100 sinking inward, which in turn helps to improve the safety and cycle life of the cylindrical cell 10.

[0054] The center pin 300 can be made of high-strength materials, such as titanium alloys, stainless steel, or ceramic matrix composites such as zirconia ceramics and silicon nitride ceramics, or metal matrix composites such as aluminum-based silicon carbide and titanium-based composites. This can make the center pin 300 have higher support strength, reduce the risk of the inner ring of the electrode assembly 100 sinking, and improve the safety and cycle life of the cylindrical cell 10.

[0055] See also Figures 3 to 5 , Figure 3 A schematic diagram of the structure of the center pin of a cylindrical battery cell provided in some embodiments of this application; Figure 4 for Figure 3 The sectional view along AA with the center pin in the middle; Figure 5 for Figure 3 The sectional view along the center pin of BB.

[0056] In some embodiments, the center pin 300 is a tubular structure, and along the axial direction X of the center pin, the center pin 300 has a first end face 310 and a second end face 320 opposite to each other. The center pin 300 is provided with a through hole 301 and a blind hole 302. Along the axial direction X of the center pin, the through hole 301 penetrates the first end face 310 and the second end face 320, and the blind hole 302 penetrates the first end face 310 but does not penetrate the second end face 320. The through hole 301 and the blind hole 302 are arranged circumferentially around the center pin 300.

[0057] By making the center needle 300 a tubular structure with an inner hole 303, gas can be contained within the inner hole 303, which helps to balance the internal gas chamber of the cylindrical cell 10. The inner hole 303 can also be used for the flow of internal gas, making the pressure relief speed of the cylindrical cell 10 faster and improving the safety of the cell.

[0058] If the center pin 300 only has a through hole 301, it will affect the supporting strength of the center pin 300. The center pin 300 cannot resist the expansion force of the electrode assembly 100 during the cycle, causing the stress concentration point of the electrode assembly 100 to deform due to compression. The inner ring of the electrode assembly 100 is at greater risk of indentation, affecting the safety and cycle life of the cylindrical cell 10. If the center pin 300 only has a blind hole 302, the gas and electrolyte in the cylindrical cell 10 can only flow through the inner hole 303 of the tubular structure of the center pin 300. The slow gas flow results in a slow depressurization rate of the cylindrical cell 10, affecting the safety of the cylindrical cell 10. The slow electrolyte flow results in poor wetting effect of the cylindrical cell 10, affecting the cycle life of the cylindrical cell 10. This application provides the center pin 300 with both a through hole 301 and a blind hole 302. Along the axial direction X of the center pin, the through hole 301 penetrates the first end face 310 and the second end face 320, and the blind hole 302 penetrates the first end face 310 but does not penetrate the second end face 320. The through hole 301 and the blind hole 302 are arranged circumferentially around the center pin 300, which not only makes the support strength of the center pin 300 higher, reducing the risk of indentation of the inner ring of the electrode assembly 100, and improving the safety and cycle life of the cylindrical cell 10, but also allows the blind hole 302 and the through hole 301 to contain gas, which is beneficial to balancing the internal gas chamber of the cylindrical cell 10. The through hole 301 can also be used for the flow of internal gas, making the pressure relief speed of the cylindrical cell 10 faster and improving the safety of the cylindrical cell 10. The through hole 301 can also be used for the flow of internal electrolyte, making the wetting effect of the cylindrical cell 10 better and improving the cycle life of the cylindrical cell 10.

[0059] In some embodiments, both the through hole 301 and the blind hole 302 can be circular holes.

[0060] In other embodiments, the through hole 301 and the blind hole 302 can also be polygonal holes such as square or hexagonal, or they can be elliptical holes, waist-shaped holes, irregular-shaped holes, etc.

[0061] In some embodiments, along the axial direction X of the center pin, the height of the center pin 300 is H0, the height of the blind hole 302 is H1, and 50% ≤ H1 / H0 ≤ 80%. For example, H1 / H0 can be 50%, 55%, 60%, 65%, 70%, 75%, or 80%, etc.

[0062] When H1 / H0 is greater than or equal to 50%, the accommodating space of the blind hole 302 is not too small, allowing for more gas to be accommodated, reducing the internal pressure of the cylindrical cell 10, thereby reducing the venting pressure of the through hole 301, reducing the possibility of the pressure relief valve of the cylindrical cell 10 opening prematurely, and thus improving the cycle life of the cylindrical cell 10; and / or, it ensures that the height of the center pin 300 is not too large, reducing the risk of the center pin 300 exceeding the electrode assembly 100 in the winding axis direction, thus reducing the overall length of the electrode assembly 100 and the center pin 300 in the winding axis direction, and improving the energy density of the cylindrical cell 10; when H1 / H0 is less than or equal to 8... The 0% H1 / H0 ratio ensures that the volume ratio of the blind hole 302 of the center pin 300 is not too large, thereby improving the support strength of the center pin 300, reducing the risk of indentation of the inner ring of the electrode assembly 100, and improving the safety and cycle life of the cylindrical cell 10. And / or, it ensures that the height of the center pin 300 is not too small, resulting in a larger support area and higher support strength for the center pin 300 on the electrode assembly 100, reducing the risk of indentation of the inner ring of the electrode assembly 100, and improving the safety and cycle life of the cylindrical cell 10. Therefore, when 50% ≤ H1 / H0 ≤ 80%, the cylindrical cell 10 has higher cycle life, energy density, and safety.

[0063] In some embodiments, the center pin 300 is provided with a plurality of through holes 301 and a plurality of blind holes 302. Along the circumference of the center pin 300, the plurality of through holes 301 are spaced apart and the plurality of blind holes 302 are spaced apart.

[0064] By providing multiple through holes 301 and multiple blind holes 302 to the center pin 300, the center pin 300 has more space to accommodate gas, which further helps to balance the internal gas chamber of the cylindrical cell 10. The multiple through holes 301 can all be used for the flow of internal gas, which further makes the pressure relief speed of the cylindrical cell 10 faster and further improves the safety of the cylindrical cell 10. The multiple through holes 301 can all be used for the flow of internal electrolyte, which further makes the wetting effect of the cylindrical cell 10 better and further improves the cycle life of the cylindrical cell 10. By distributing multiple through holes 301 and multiple blind holes 302 at intervals along the circumference of the center pin 300, the distribution of the multiple through holes 301 and multiple blind holes 302 in the circumference of the center pin 300 becomes more uniform. This makes the supporting force of the center pin 300 on the electrode assembly 100 more uniform, reducing the occurrence of stress concentration points in the electrode assembly 100. This helps to reduce the risk of indentation of the inner ring of the electrode assembly 100 and improves the safety and cycle life of the cylindrical cell 10.

[0065] In some embodiments, through holes 301 and blind holes 302 are alternately spaced along the circumference of the center pin 300.

[0066] By alternating the through holes 301 and blind holes 302 along the circumference of the center pin 300, the distribution of through holes 301 and blind holes 302 in the circumference of the center pin 300 becomes more uniform. This results in a more uniform distribution of the supporting force of the center pin 300 on the electrode assembly 100, further reducing the occurrence of stress concentration points in the electrode assembly 100. This also helps to further reduce the risk of indentation of the inner ring of the electrode assembly 100, and further improves the safety and cycle life of the cylindrical cell 10.

[0067] In some embodiments, the distances from each through hole 301 to the axis P of the center pin 300 are equal, the distances from each blind hole 302 to the axis P of the center pin 300 are equal, and the distance from the through hole 301 to the axis P of the center pin 300 is less than the distance from the blind hole 302 to the axis P of the center pin 300.

[0068] By making the distances from each through hole 301 to the axis P of the center pin 300 equal, and the distances from each blind hole 302 to the axis P of the center pin 300 equal, the force on the center pin 300 and the supporting force on the electrode assembly 100 when the electrode assembly 100 expands can be made more uniform. This can further reduce the occurrence of stress concentration points in the electrode assembly 100, which is beneficial to further reduce the risk of indentation of the inner ring of the electrode assembly 100, and further improve the safety and cycle life of the cylindrical cell 10. Since the portion of the center pin 300 with blind hole 302 has stronger supporting force than the portion with through hole 301, by making the distance from through hole 301 to the axis P of the center pin 300 smaller than the distance from blind hole 302 to the axis P of the center pin 300, i.e., the blind hole 302 is closer to the outer surface of the center pin 300, the portion of the center pin 300 with blind hole 302 can be stressed before the portion with through hole 301. The supporting effect of the center pin 300 is better, which helps to further reduce the risk of indentation of the inner ring of the electrode assembly 100 and further improve the safety and cycle life of the cylindrical cell 10.

[0069] In some embodiments, along the circumference of the center pin 300, the distance from any through hole 301 to the blind holes 302 located on both sides of the through hole 301 is equal.

[0070] The distance between the through hole 301 and the adjacent blind hole 302 is the shortest distance from the edge of the through hole 301 to the edge of the adjacent blind hole 302.

[0071] By making the distance from any through hole 301 to the blind holes 302 located on both sides of the through hole 301 equal along the circumference of the center pin 300, the through holes 301 and blind holes 302 can be further evenly distributed in the circumference of the center pin 300. This makes the supporting force of the center pin 300 on the electrode assembly 100 more evenly distributed, further reducing the occurrence of stress concentration points in the electrode assembly 100. This is beneficial to further reduce the risk of indentation of the inner ring of the electrode assembly 100, and further improve the safety and cycle life of the cylindrical cell 10.

[0072] In some embodiments, the sum of the cross-sectional areas of the plurality of through holes 301 is S1, and the sum of the cross-sectional areas of the plurality of blind holes 302 is S2, where 0.8 ≤ S2 / S1 ≤ 1.2. For example, S2 / S1 can be 0.8, 0.9, 1, 1.1, or 1.2, etc.

[0073] When S2 / S1 is greater than or equal to 0.8, the sum of the cross-sectional areas of the multiple blind holes 302 is not too small, thus ensuring that the sum of the volumes of the multiple blind holes 302 is not too small. This allows the multiple blind holes 302 to accommodate more gas, reducing the internal pressure of the cylindrical cell 10, thereby reducing the pressure of the through holes 301 and decreasing the possibility of the pressure relief valve of the cylindrical cell 10 opening prematurely, which is beneficial to improving the cycle life of the cylindrical cell 10; and / or, the cross-sectional area of ​​the multiple through holes 301 is not too large, thus ensuring that the sum of the volumes of the multiple through holes 301 is not too large, which is beneficial to improving the support strength of the center pin 300, reducing the risk of indentation of the inner ring of the electrode assembly 100, and improving the safety and cycle life of the cylindrical cell 10; when S2 / When S1 is less than or equal to 1.2, the sum of the cross-sectional areas of the multiple blind holes 302 is not too large, and thus the sum of the volumes of the multiple blind holes 302 is not too large. This is beneficial to improving the support strength of the center pin 300, reducing the risk of indentation of the inner ring of the electrode assembly 100, and improving the safety and cycle life of the cylindrical cell 10. And / or, the cross-sectional area of ​​the multiple through holes 301 is not too small, and thus the sum of the volumes of the multiple through holes 301 is not too small. This allows the multiple through holes 301 to accommodate more gas, reducing the internal pressure of the cylindrical cell 10, which is beneficial to improving the cycle life of the cylindrical cell 10. It also allows the multiple through holes 301 to accommodate more electrolyte, which improves the wetting effect of the cylindrical cell 10, which is beneficial to improving the cycle life of the cylindrical cell 10, and also allows the cylindrical cell 10 to depressurize faster, improving the safety of the cylindrical cell 10. Therefore, when 0.8≤S2 / S1≤1.2, the cylindrical cell 10 has high safety and cycle life.

[0074] In some embodiments, the cross-sectional area of ​​the center pin 300 is S0, and the sum of the cross-sectional areas of the plurality of through holes 301 is S1, where 10% ≤ S1 / S0 ≤ 40%. For example, S1 / S0 can be 10%, 15%, 20%, 25%, 30%, 35%, or 40%, etc.

[0075] When S1 / S0 is greater than or equal to 10%, the cross-sectional area of ​​the multiple through holes 301 is not too small, thus ensuring that the total volume of the multiple through holes 301 is not too small. This allows the multiple through holes 301 to accommodate more gas, reducing the internal pressure of the cylindrical cell 10 and improving its cycle life. It also allows the multiple through holes 301 to accommodate more electrolyte, improving the wetting effect of the cylindrical cell 10 and further enhancing its cycle life. Furthermore, it allows for faster pressure relief, improving the safety of the cylindrical cell 10. And / or, the cross-sectional area of ​​the center pin 300 is not too large. With the outer diameter of the center pin 300 unchanged, the inner diameter of the center pin 300 is not too small, facilitating gas flow through the inner hole 303 of the center pin 300, resulting in faster pressure relief and improved cell safety. When S1 / When S0 is less than or equal to 40%, the cross-sectional area of ​​the multiple through holes 301 is not too large, and thus the total volume of the multiple through holes 301 is not too large. This is beneficial to improving the support strength of the center pin 300, reducing the risk of indentation of the inner ring of the electrode assembly 100, and improving the safety and cycle life of the cylindrical cell 10. And / or, the cross-sectional area of ​​the center pin 300 is not too small, which can improve the support strength of the center pin 300, reduce the risk of indentation of the inner ring of the electrode assembly 100, and improve the safety and cycle life of the cylindrical cell 10. Therefore, when 10%≤S1 / S0≤40%, the cylindrical cell 10 has high safety and cycle life.

[0076] In some embodiments, the sum of the cross-sectional areas of the plurality of blind holes 302 is S2, and 10% ≤ S2 / S0 ≤ 30%. For example, S2 / S0 can be 10%, 12%, 15%, 17%, 20%, 22%, 25%, 28%, or 30%, etc.

[0077] When S2 / S0 is greater than or equal to 10%, the sum of the cross-sectional areas of the multiple blind holes 302 is not too small, thus ensuring that the sum of the volumes of the multiple blind holes 302 is not too small. This allows the multiple blind holes 302 to accommodate more gas, reducing the internal pressure of the cylindrical cell 10, thereby reducing the pressure of the exhaust through the through hole 301 and reducing the possibility of the pressure relief valve of the cylindrical cell 10 opening prematurely, which is beneficial to improving the cycle life of the cylindrical cell 10; and / or, the cross-sectional area of ​​the center pin 300 is not too large. With the outer diameter of the center pin 300 unchanged, the inner diameter of the center pin 300 is not too small, facilitating the flow of gas through the inner hole 303 of the center pin 300, resulting in a faster pressure relief speed of the cylindrical cell 10 and improving the safety of the cell; when S2 / When S0 is less than or equal to 30%, the sum of the cross-sectional areas of the multiple blind holes 302 will not be too large, and thus the sum of the volumes of the multiple blind holes 302 will not be too large. This is beneficial to improving the support strength of the center pin 300, reducing the risk of indentation of the inner ring of the electrode assembly 100, and improving the safety and cycle life of the cylindrical cell 10. And / or, the cross-sectional area of ​​the center pin 300 will not be too small, which can improve the support strength of the center pin 300, reduce the risk of indentation of the inner ring of the electrode assembly 100, and improve the safety and cycle life of the cylindrical cell 10. Therefore, when 10%≤S2 / S0≤30%, the cylindrical cell 10 has high safety and cycle life.

[0078] In some embodiments, the distance between any adjacent through hole 301 and blind hole 302 is G, where 0.5mm ≤ G ≤ 1mm. For example, G can be 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, or 1mm, etc.

[0079] When G is greater than or equal to 0.5 mm, the distribution density of through holes 301 and blind holes 302 on the center pin 300 is not too large, reducing the space occupied by through holes 301 and blind holes 302, which helps to improve the support strength of the center pin 300, reduces the risk of indentation of the inner ring of the electrode assembly 100, helps to improve the safety and cycle life of the cylindrical cell 10, and reduces the possibility of partial fracture between through holes 301 and blind holes 302 under stress; when G is less than or equal to 1 mm, the distribution density of through holes 301 and blind holes 302 on the center pin 300 is not too large. The distribution density will not be too low. The center pin 300 has more through holes 301 and blind holes 302 to accommodate gas, which can reduce the internal pressure of the cylindrical cell 10 and improve its cycle life. The center pin 300 has more through holes 301 to accommodate electrolyte, which can improve the wetting effect of the cylindrical cell 10 and improve its cycle life. It can also make the pressure relief speed of the cylindrical cell 10 faster, improve the safety of the cell, and reduce the possibility of gas bypassing the blind holes 302 and then escaping, which can help reduce the flow resistance of the gas. This reduces the venting pressure in the through-hole, decreasing the likelihood of premature opening of the pressure relief valve and thus improving the cycle life of the cylindrical cell 10. Therefore, when 0.5mm ≤ G ≤ 1mm, it not only improves the support strength of the center pin 300 and reduces the risk of indentation of the inner ring of the electrode assembly 100, thus improving the safety and cycle life of the cylindrical cell 10, but also reduces the possibility of partial fracture between the through-hole 301 and blind hole 302 under stress. Furthermore, it allows the center pin 300 to have more through-holes 301 and blind holes 302 for accommodating gas, reducing the risk of premature opening of the pressure relief valve. The internal pressure of the cylindrical cell 10 is beneficial to improving the cycle life of the cylindrical cell 10. The center pin 300 has more through holes 301 to accommodate electrolyte, which can improve the wetting effect of the cylindrical cell 10, thus improving the cycle life of the cylindrical cell 10. It can also make the pressure relief speed of the cylindrical cell 10 faster, improving the safety of the cell. It can also reduce the possibility of gas bypassing the blind hole 302 and then being discharged, which can reduce the flow resistance of gas, thereby reducing the venting pressure of the through hole and reducing the possibility of the pressure relief valve opening prematurely, which can also improve the cycle life of the cylindrical cell 10.

[0080] In some embodiments, along the radial direction Y of the center pin, the wall thickness of the center pin 300 is T, and the diameter of the through hole 301 is D1, where 0.1 ≤ D1 / T ≤ 0.3. For example, D1 / T can be 0.1, 0.12, 0.15, 0.18, 0.2, 0.23, 0.27, or 0.3, etc.

[0081] When D1 / T is greater than or equal to 0.1, the diameter of the through-hole 301 is not too small, thus ensuring its volume is not too small. This allows the through-hole 301 to accommodate more gas, reducing the internal pressure of the cylindrical cell 10 and improving its cycle life. It also allows the through-hole 301 to accommodate more electrolyte, improving its wetting effect and cycle life. Furthermore, it facilitates gas and electrolyte flow, reducing the risk of blockage and allowing for faster pressure relief, thus enhancing cell safety. And / or, the wall thickness of the center pin 300 is not too large. With the outer diameter of the center pin 300 unchanged, its inner diameter is not too small, facilitating gas flow through the inner hole 303 of the center pin 300. This results in faster pressure relief for the cylindrical cell 10, improving its safety and allowing for easier electrolyte flow through the center pin. The flow within the inner hole 303 of the needle 300 improves the wetting effect of the cylindrical cell 10, thus increasing its cycle life. When D1 / T is less than or equal to 0.3, the diameter of the through hole 301 is not too large, which helps to improve the support strength of the center needle 300, reduces the risk of indentation of the inner ring of the electrode assembly 100, and improves the safety and cycle life of the cylindrical cell 10. Furthermore, in the early stage of thermal runaway of the cylindrical cell 10, the gas will not be directly and rapidly discharged, reducing the possibility of electrolyte splashing caused by a sudden drop in internal pressure. And / or, the wall thickness of the center needle 300 is not too small, which can improve the support strength of the center needle 300, reduce the risk of indentation of the inner ring of the electrode assembly 100, and improve the safety and cycle life of the cylindrical cell 10. Therefore, when 0.1≤D1 / T≤0.3, the cylindrical cell 10 has high safety and cycle life.

[0082] In some embodiments, the diameter of the blind hole 302 is D2, where 0.05 ≤ D2 / T ≤ 0.2. For example, D2 / T can be 0.05, 0.07, 0.09, 0.1, 0.12, 0.13, 0.15, 0.18, 0.19, or 0.2, etc.

[0083] When D2 / T is greater than or equal to 0.05, the diameter of the blind hole 302 is not too small, thus ensuring that its volume is not too small. This allows the blind hole 302 to hold more gas, reducing the internal pressure of the cylindrical cell 10, thereby reducing the pressure of the exhaust through the through hole 301 and decreasing the likelihood of premature opening of the pressure relief valve of the cylindrical cell 10, which is beneficial for improving the cycle life of the cylindrical cell 10. And / or, the wall thickness of the center pin 300 is not too large. With the outer diameter of the center pin 300 remaining constant, its inner diameter is not too small, facilitating gas flow through the inner hole 303 of the center pin 300, thus reducing the pressure relief rate of the cylindrical cell 10. Faster speed improves cell safety; when D2 / T is less than or equal to 0.2, the diameter of the blind hole 302 will not be too large, which helps to improve the support strength of the center pin 300, reduce the risk of the inner ring of the electrode assembly 100 sinking, and improve the safety and cycle life of the cylindrical cell 10; and / or, the wall thickness of the center pin 300 will not be too small, which can improve the support strength of the center pin 300, reduce the risk of the inner ring of the electrode assembly 100 sinking, and improve the safety and cycle life of the cylindrical cell 10; therefore, when 0.05≤D2 / T≤0.2, the cylindrical cell 10 has high safety and cycle life.

[0084] In some embodiments, the number of through holes 301 is equal to the number of blind holes 302.

[0085] See Figure 2 and Figure 6 , Figure 6 This is a schematic diagram of the negative electrode of a cylindrical battery cell provided in some embodiments of this application.

[0086] In other embodiments, the electrode assembly 100 includes a negative electrode 120, which includes a negative current collector 121 and a negative active material layer 122. The negative active material layer 122 is disposed on at least one side of the negative current collector 121 along its thickness direction Z. The negative active material layer 122 includes a silicon-based material. The coefficient of thermal expansion of the negative electrode 120 is k, the number of through holes 301 is N1, the number of blind holes 302 is N2, 0.1≤k≤0.5, and 10%≤N2 / N1≤40%. For example, k can be 0.1, 0.2, 0.3, 0.4, or 0.5, etc. For example, N2 / N1 can be 10%, 15%, 20%, 25%, 30%, 35%, or 40%, etc.

[0087] When 0.1≤k≤0.5, the expansion coefficient of the negative electrode 120 is small, and the pressure acting on the center pin 300 during the electrode assembly 100 cycle is small, corresponding to 10%≤N2 / N1≤40%, that is, the number of through holes 301 is greater than the number of blind holes 302, so that the center pin 300 has more space to accommodate gas while having a certain supporting strength, which can reduce the internal pressure of the cylindrical cell 10, which is beneficial to improve the cycle life of the cylindrical cell 10, and can make the pressure relief speed of the cylindrical cell 10 faster, thus improving the safety of the cell.

[0088] In other embodiments, 0.5 < k ≤ 1.0, and 70% ≤ N2 / N1 ≤ 95%. For example, k can be 0.51, 0.6, 0.7, 0.8, 0.9, or 1.0, etc. For example, N2 / N1 can be 70%, 75%, 80%, 85%, 90%, 92%, or 95%, etc.

[0089] When 0.5 < k ≤ 1.0, the expansion coefficient of the negative electrode 120 is relatively large, and the pressure exerted on the center pin 300 by the electrode assembly 100 during the cycle is relatively large. Corresponding to 70% ≤ N2 / N1 ≤ 95%, that is, the number of blind holes 302 is greater than the number of through holes 301, which makes the support strength of the center pin 300 higher, reduces the risk of the inner ring of the electrode assembly 100 sinking, and helps to improve the safety and cycle life of the cylindrical cell 10.

[0090] See Figure 1 and Figure 5 In some embodiments, the electrode assembly 100 includes a main body 100a, a positive electrode tab 140, and a negative electrode tab 150. The positive electrode tab 140 is disposed at a first end of the main body 100a along the winding axis of the electrode assembly 100, and the negative electrode tab 150 is disposed at a second end of the main body 100a along the winding axis. The first end and the second end are respectively the two ends of the electrode assembly 100 along the winding axis. The first end face 310 is closer to the positive electrode tab 140 than the second end face 320.

[0091] Since more heat is generated at the positive electrode tab 140, more gas is produced. By making the first end face 310 closer to the positive electrode tab 140 than the second end face 320, that is, the opening of the blind hole 302 faces the positive electrode tab, the gas generated near the positive electrode tab 140 can quickly enter the blind hole 302. This helps to reduce the unevenness of the internal pressure of the cylindrical cell 10 and improve the cycle life of the cylindrical cell 10.

[0092] See Figure 4 In some embodiments, the outer diameter D3 of the center pin 300 along the radial direction Y of the center pin is 2mm-5mm. For example, the outer diameter D3 of the center pin 300 can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm or 5mm, etc.

[0093] When the outer diameter D3 of the center pin 300 is greater than or equal to 2 mm, it facilitates the contact between the electrode assembly 100 and the outer peripheral surface of the center pin 300 when the electrode assembly 100 expands, allowing the center pin 300 to provide support for the electrode assembly 100. This reduces the risk of indentation of the inner ring of the electrode assembly 100, which is beneficial to improving the safety and cycle life of the cylindrical cell 10. When the outer diameter D3 of the center pin 300 is less than or equal to 5 mm, it facilitates the assembly of the center pin 300 with the electrode assembly 100, which is beneficial to improving the manufacturing efficiency of the cell. Therefore, when the outer diameter D3 of the center pin 300 is between 2 mm and 5 mm, it not only facilitates the contact between the electrode assembly 100 and the outer peripheral surface of the center pin 300 when the electrode assembly 100 expands, allowing the center pin 300 to provide support for the electrode assembly 100, thus reducing the risk of indentation of the inner ring of the electrode assembly 100 and improving the safety and cycle life of the cylindrical cell 10, but also facilitates the assembly of the center pin 300 with the electrode assembly 100, which is beneficial to improving the manufacturing efficiency of the cell.

[0094] In some embodiments, the inner diameter D4 of the center pin 300 along the radial direction Y of the center pin is 1mm-3mm. For example, the inner diameter D4 of the center pin 300 can be 1mm, 1.5mm, 2mm, 2.5mm or 3mm, etc.

[0095] When the inner diameter D4 of the center pin 300 is greater than or equal to 1 mm, the volume of the inner hole 303 of the center pin 300 is not too small, facilitating gas flow through the inner hole 303 of the center pin 300. This results in faster pressure relief of the cylindrical battery cell 10, improving its safety. It also facilitates electrolyte flow through the inner hole 303 of the center pin 300, leading to better wetting of the cylindrical battery cell 10 and increasing its cycle life. When the inner diameter D4 of the center pin 300 is less than or equal to 3 mm, the volume of the inner hole 303 can be reduced. The space occupied is beneficial to improving the energy density of the battery cell. Therefore, when the inner diameter D4 of the center pin 300 is 1mm-3mm, it can facilitate the flow of gas through the inner hole 303 of the center pin 300, making the pressure relief speed of the cylindrical battery cell 10 faster and improving the safety of the cylindrical battery cell 10. It can also facilitate the flow of electrolyte through the inner hole 303 of the center pin 300, making the wetting effect of the cylindrical battery cell 10 better and improving the cycle life of the cylindrical battery cell 10. At the same time, it can reduce the space occupied by the inner hole 303, which is beneficial to improving the energy density of the battery cell.

[0096] In some embodiments, the wall thickness T of the center pin 300 along the radial direction Y of the center pin is 0.5 mm to 1 mm. For example, the wall thickness T of the center pin 300 can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1 mm, etc.

[0097] When the wall thickness T of the center pin 300 is greater than or equal to 0.5 mm, it ensures that the wall thickness is not too small, thereby improving the support strength of the center pin 300 and reducing the risk of indentation of the inner ring of the electrode assembly 100. This is beneficial for improving the safety and cycle life of the cylindrical cell 10. When the wall thickness T of the center pin 300 is less than or equal to 1 mm, it ensures that the wall thickness is not too large. With the outer diameter of the center pin 300 remaining unchanged, the inner diameter of the center pin 300 will not be too small, facilitating the flow of gas through the inner hole 303 of the center pin 300. This allows for faster depressurization of the cylindrical cell 10, improving the safety of the cylindrical cell 10 and facilitating the flow of electrolyte through the center pin 300. The flow of electrolyte through the inner hole 303 improves the wetting effect of the cylindrical cell 10 and increases its cycle life. Therefore, when the wall thickness T of the center pin 300 is 0.5mm-1mm, it can not only improve the support strength of the center pin 300 and reduce the risk of indentation of the inner ring of the electrode assembly 100, which is beneficial to improving the safety and cycle life of the cylindrical cell 10, but also facilitate the flow of gas through the inner hole 303 of the center pin 300, making the pressure relief speed of the cylindrical cell 10 faster and improving its safety. It also facilitates the flow of electrolyte through the inner hole 303 of the center pin 300, making the wetting effect of the cylindrical cell 10 better and increasing its cycle life.

[0098] In some embodiments, the cylindrical cell 10 further includes a first current collector 410, and the housing 200 is provided with a terminal post 210, which is insulated from the housing 200. The first current collector 410 can be connected to the terminal post 210, so that the positive electrode tab 140 is electrically connected to the terminal post 210 through the first current collector 410.

[0099] In some embodiments, the cylindrical cell 10 further includes a second current collector 420, through which the negative electrode tab 150 is electrically connected to the housing 200.

[0100] This application provides an electrical device including a cylindrical battery cell 10 provided in any of the above embodiments, the cylindrical battery cell 10 being used to provide electrical energy.

[0101] Manufacturing method of cylindrical battery cells: <Preparation of the positive electrode> The positive electrode active material is lithium nickel cobalt manganese oxide (LiNi). 0.91 Co 0.045 Mn 0.045O2), polyvinylidene fluoride (PVDF) binder, and conductive carbon black were dispersed in N-methylpyrrolidone (NMP) solvent at a mass ratio of 97.1:1.6:1.3 and thoroughly mixed to obtain a positive electrode slurry with a solid content of 72 wt%. The positive electrode slurry was uniformly coated on one surface of a 13 μm thick aluminum foil for the positive electrode current collector and dried at 105 °C to obtain a positive electrode sheet with a first positive electrode material layer coated on one side. The above steps were then repeated on the other surface of the same aluminum foil to obtain a positive electrode sheet with both a first and a second positive electrode material layer coated.

[0102] The positive electrode sheet has dimensions of 66.5mm × 1688mm, and the coating weight of the first and second positive electrode material layers is 196.5mg / 1540.25mm. 2 The first positive electrode material layer has a size of 60mm × 1688mm, the second positive electrode material layer has the same size as the first positive electrode material layer, and the width of the empty foil area of ​​the positive electrode sheet is 4.5mm.

[0103] <Preparation of Negative Electrode Sheets> Artificial graphite (anode active material), silicon carbide (SiC) (anode active material), sodium carboxymethyl cellulose (CMC-Na), and styrene-butadiene rubber (SBR) were mixed in a mass ratio of 82.45:14.55:1.7:1.3. Deionized water was then added as a solvent, and the mixture was stirred until homogeneous, yielding a cathode slurry with a solid content of 50 wt%. This cathode slurry was uniformly coated onto one surface of an 8 μm thick copper foil current collector and dried at 105 °C to obtain a cathode sheet with a single-sided coating of the first cathode material layer. The above steps were then repeated on the other surface of the same copper foil to obtain a cathode sheet coated with both the first and second cathode material layers.

[0104] The negative electrode sheet has dimensions of 67.45mm × 1730mm, and the coating weight of the first and second negative electrode material layers is 78mg / 1540.25mm. 2 The first negative electrode material layer has a size of 62mm × 1730mm, the second negative electrode material layer has the same size as the first negative electrode material layer, the sum of the thickness of the first negative electrode material layer and the negative electrode current collector is 40μm, and the width of the empty foil area of ​​the negative electrode sheet is 5.45mm.

[0105] <Isolation membrane> A polyethylene (PE) film with a thickness of 12μm was used as the separator.

[0106] <Preparation of Electrolyte> In a dry argon-atmospheric glove box, ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a mass ratio of 30:50:20 to obtain a base solvent. Lithium hexafluorophosphate (LiPF6) was then added to the base solvent and mixed thoroughly to obtain the electrolyte. Based on the mass of the electrolyte, the mass percentage of LiPF6 was 12.5%, with the remainder being the base solvent.

[0107] <Preparation of Cylindrical Cells> The separator, negative electrode, separator, and positive electrode prepared above are stacked sequentially and pre-wound, with the separator positioned between the negative and positive electrode sheets. Simultaneously, the first positive electrode material layer is positioned away from the center of the pre-wound electrode assembly, and the starting end of the first positive electrode material layer is located close to the center of the pre-wound electrode assembly. Then, the assembly is wound into an electrode assembly with a central hole using a 3.0 mm diameter needle. After removing the needle, a central needle with an outer diameter of 2.4 mm, a wall thickness of 0.5 mm, and a height of 60 mm is inserted into the central hole.

[0108] After the electrode assembly is installed in the casing, electrolyte is injected, it is sealed, and then subjected to high-temperature settling and formation, a cylindrical battery cell can be obtained. The upper limit voltage for formation is 3.6V, and the formation temperature is 45℃.

[0109] Refer to Table 1. In Table 1, S0 is the cross-sectional area of ​​the central pin, S1 is the sum of the cross-sectional areas of the multiple through holes on the central pin, S2 is the sum of the cross-sectional areas of the multiple blind holes on the central pin, H0 is the height of the central pin, and H1 is the height of the blind holes. In Comparative Example 1, the central pin is a solid tubular structure without through holes or blind holes. In Comparative Example 2, the central pin only has through holes. In Comparative Example 3, the central pin only has blind holes. In Examples 1-9, the central pin has both through holes and blind holes.

[0110] Table 1

[0111] Test method for the indentation distance of electrode assembly: (1) Cyclic cells are charged and discharged at an ambient temperature of 25±2℃. The charging and discharging voltage range is 2.5V to 4.2V. They are charged to 4.2V with a constant current of 3C, then charged to 0.05C with a constant voltage of 4.2V and left to stand for 5 minutes. Then they are discharged to 2.5V with a constant current of 6C. The above charging and discharging process is repeated 600 times.

[0112] (2) After the cylindrical battery cell is fully charged, industrial computed tomography (industrial CT, Zeiss Xradia620 Versa) is used to perform CT scans on the wound electrode assembly along the radial direction of the electrode assembly.

[0113] (3) See Figure 7 , Figure 7 The scan image of the electrode assembly after 600 cycles of charging and discharging of the cylindrical battery cell provided in some embodiments of this application is defined as point E, the maximum indentation position of the electrode assembly (the point where the indentation is closest to the winding axis) is defined as point E, and the indentation position of the electrode assembly (the electrode plate with a height greater than or equal to 0.2 mm protruding towards the winding axis is defined as point F) is defined as point F. The distance between point E and point F is the indentation distance of the electrode assembly.

[0114] Cycle capacity retention test of cylindrical cells: (1) Cyclic cells are charged and discharged in a constant temperature chamber at 25°C. They are charged to 4.2V with a constant current of 3C and then charged to 0.05C with a constant voltage of 4.2V. After standing for 5 minutes, they are discharged to 2.5V with a constant current of 6C. This is the first cycle. The discharge capacity C1 of the first cycle is recorded.

[0115] (2) After 600 cycles of the above cycle process, record the discharge capacity C600 of the cylindrical cell. Then the capacity retention rate (%) of the 600th cycle is C600 / C1×100%.

[0116] Based on Table 1, the following conclusions can be drawn: (1) Referring to Comparative Examples 1-3 and Examples 1-9, if the center pin does not have through holes or blind holes (Comparative Example 1), the space inside the cylindrical cell for accommodating gas is smaller. During the cyclic charging and discharging process, the cylindrical cell is prone to generating large pressure, causing the pressure relief valve of the cylindrical cell to open prematurely, which will reduce the cycle capacity retention rate of the cylindrical cell and thus result in a lower cycle life. If the center pin only has through holes (Example 2), it will affect the support strength of the center pin. The center pin cannot resist the expansion force of the electrode assembly during the cycle, causing the stress concentration point of the electrode assembly to deform due to compression. The indentation distance of the electrode assembly is larger, which will reduce the cycle capacity retention rate of the cylindrical cell and thus result in a lower cycle life. If the center pin only has blind holes (Comparative Example 3), the gas inside the cylindrical cell can only flow through the inner hole of the tubular structure of the center pin. The slow gas flow makes the pressure relief speed of the cylindrical cell slower, causing the pressure relief valve of the cylindrical cell to open prematurely, which will reduce the cycle capacity retention rate of the cylindrical cell and thus result in a lower cycle life. The center pin of this application is provided with through holes and blind holes (Examples 1-9), which can not only make the support strength of the center pin higher and reduce the risk of indentation of the inner ring of the electrode assembly, but also allow the blind holes and through holes to accommodate gas, which is beneficial to balance the internal gas chamber of the cylindrical cell. The through holes can also be used for the flow of internal gas, which makes the pressure relief speed of the cylindrical cell faster. Therefore, the indentation distance of the cylindrical cell is smaller, while reducing the cycle capacity retention rate of the cylindrical cell, thereby making the cycle life of the cylindrical cell higher.

[0117] (2) Referring to Examples 1-5, when S1 / S0 is less than 10% and S2 / S0 is less than 10%, the sum of the cross-sectional areas of the multiple through holes and the sum of the cross-sectional areas of the multiple blind holes is small, resulting in a smaller sum of the volumes of the multiple through holes and the multiple blind holes. This means that less gas can be contained, and the internal pressure of the cylindrical cell is larger, causing the pressure relief valve of the cylindrical cell to open earlier, which reduces the cycle capacity retention rate of the cylindrical cell and thus results in a lower cycle life. When S1 / S0 is greater than 40% and S2 / S0 is greater than 30%, the sum of the cross-sectional areas of the multiple through holes and the sum of the cross-sectional areas of the multiple blind holes is larger, resulting in lower support strength of the center pin. This increases the risk of indentation of the inner ring of the electrode assembly, resulting in a larger indentation distance of the electrode assembly, which reduces the cycle capacity retention rate of the cylindrical cell and thus reduces the cycle life of the cylindrical cell. When 10%≤S1 / S0≤40% and 10%≤S2 / S0≤30%, the indentation distance of the cylindrical cell can be smaller, the cycle capacity retention rate of the cylindrical cell can be higher, and the cycle life of the cylindrical cell can be higher.

[0118] (3) Referring to Examples 3 and 6-9, when H1 / H0 is less than 50%, the volume of the blind hole is small, and it can hold less gas. The internal pressure of the cylindrical cell is large, which causes the pressure relief valve of the cylindrical cell to open earlier, which will reduce the cycle capacity retention rate of the cylindrical cell and thus make the cycle life of the cylindrical cell low. When H1 / H0 is greater than 80%, the volume of the blind hole is large, and the support strength of the center pin is low, which increases the risk of the inner ring of the electrode assembly sinking, resulting in a large sinking distance of the electrode assembly, which will reduce the cycle capacity retention rate of the cylindrical cell and thus make the cycle life of the cylindrical cell low. When 50%≤H1 / H0≤80%, the sinking distance of the cylindrical cell is small, and the cycle capacity retention rate of the cylindrical cell is high, resulting in a high cycle life of the cylindrical cell.

[0119] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0120] The above are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A cylindrical cell, characterized by, The electrode assembly comprises: an electrode assembly with a winding structure, the electrode assembly having a central hole; a central needle arranged in the central hole, the central needle being a tubular structure, along the axial direction of the central needle, the central needle having opposite first and second end faces; the central needle is provided with a through hole and a blind hole, along the axial direction of the central needle, the through hole penetrates the first end face and the second end face, the blind hole penetrates the first end face and does not penetrate the second end face, the through hole and the blind hole are arranged at intervals around the circumference of the central needle.

2. The cylindrical cell of claim 1, wherein, Along the axial direction of the central needle, the height of the central needle is H0, the height of the blind hole is H1, 50%≤H1 / H0≤80%.

3. The cylindrical cell of claim 1, wherein, The central needle is provided with a plurality of through holes and a plurality of blind holes, and the plurality of through holes and the plurality of blind holes are arranged at intervals along the circumferential direction of the central needle.

4. The cylindrical cell of claim 3, wherein, Along the circumferential direction of the central needle, the through holes and the blind holes are alternately arranged at intervals.

5. The cylindrical cell of claim 4, wherein, The distance of each through hole to the axis of the central needle is equal, the distance of each blind hole to the axis of the central needle is equal, and the distance of the through hole to the axis of the central needle is less than the distance of the blind hole to the axis of the central needle.

6. The cylindrical cell of claim 5, wherein, Along the circumferential direction of the central needle, the distance of any through hole to the blind holes located on both sides of the through hole is equal.

7. The cylindrical cell of claim 3, wherein, The total cross-sectional area of the plurality of through holes is S1, and the total cross-sectional area of the plurality of blind holes is S2, 0.8≤S2 / S1≤1.

2.

8. The cylindrical cell of claim 3, wherein, The cross-sectional area of the central needle is S0, the total cross-sectional area of the plurality of through holes is S1, 10%≤S1 / S0≤40%; the total cross-sectional area of the plurality of blind holes is S2, 10%≤S2 / S0≤30%.

9. The cylindrical cell of claim 3, wherein, The distance between any adjacent through hole and blind hole is G, 0.5mm≤G≤1mm.

10. The cylindrical cell of claim 1, wherein, Along the radial direction of the central needle, the wall thickness of the central needle is T, the diameter of the through hole is D1, 0.1≤D1 / T≤0.3; and / or, The diameter of the blind hole is D2, 0.05≤D2 / T≤0.

2.

11. The cylindrical cell of claim 1, wherein, The electrode assembly comprises a negative electrode tab, the negative electrode tab comprising a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer being arranged on at least one side of the negative electrode current collector in the thickness direction thereof, the negative electrode active material layer comprising a silicon-based material, the negative electrode tab having an expansion coefficient k, the number of through holes being N1, the number of blind holes being N2, 0.1≤k≤0.5, 10%≤N2 / N1≤40%; or, 0.5≤k≤1.0, 70%≤N2 / N1≤95%.

12. The cylindrical cell of claim 1, wherein, The electrode assembly comprises a main body, a positive electrode tab and a negative electrode tab, the positive electrode tab being arranged at the first end of the main body in the winding axis direction of the electrode assembly, the negative electrode tab being arranged at the second end of the main body in the winding axis direction, the first end and the second end being the two ends of the electrode assembly in the winding axis direction respectively; The first end face is closer to the positive electrode tab than the second end face.

13. The cylindrical cell of claim 1, wherein, In a radial direction of the center needle, an outer diameter of the center needle is 2mm-5mm, an inner diameter of the center needle is 1mm-3mm, and a wall thickness of the center needle is 0.5mm-1mm.

14. An electrical device, characterized by A cylindrical battery cell as claimed in any one of claims 1-13 for providing electrical energy.

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