Battery cell, battery device, and electric device

Abstract

Provided are a battery cell, a battery device, and an electric device. The battery cell comprises a housing and a pressure relief mechanism, the housing having a first wall portion, and the pressure relief mechanism being disposed on the first wall portion. The base material of the pressure relief mechanism is iron, and the pressure relief mechanism includes a weakened portion configured to be at least partially damaged so as to release pressure when the pressure inside the housing reaches a threshold. The weakest regions of the weakened portion are located on at least two sides of the weakened portion in the direction of width of the first wall portion. The weakest regions of the weakened portion are located on at least two sides of the weakened portion in the direction of width of the first wall portion, so that when the pressure inside the housing reaches the threshold, the two sides of the weakened portion in the direction of width of the first wall portion will fracture first. Even if the pressure relief zone defined by the weakened portion is not completely opened, the ejected high-temperature gas will not easily diffuse in the direction of width of the first wall portion, and will not easily diffuse to another battery cell adjacent thereto, thus being less likely to cause the thermal runaway of the another battery cell, which helps to improve the reliability of the battery device.

Description

Battery cell, battery device and electric device TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to a battery cell, a battery device and an electric device. BACKGROUND

[0002] Batteries are widely used in the field of new energy, for example, electric vehicles, new energy vehicles, etc. New energy vehicles and electric vehicles have become a new trend in the development of the automobile industry. The development of battery technology needs to consider various design factors, such as energy density, discharge capacity, charge-discharge rate and other performance parameters. In addition, the reliability of the battery also needs to be considered. However, the reliability of the current battery is poor.

[0003] SUMMARY

[0004] The purpose of the embodiments of the present application is to provide a battery cell, a battery device and an electric device, which aims to improve the problem of poor reliability of the battery cell in the related art.

[0005] In a first aspect, the embodiments of the present application provide a battery cell, which comprises a shell and a pressure relief mechanism, the shell has a first wall part, the pressure relief mechanism is arranged on the first wall part, the base material of the pressure relief mechanism is iron, the pressure relief mechanism comprises a weak part, the weak part is configured to be at least partially destroyed to release pressure when the pressure inside the shell reaches a threshold value; wherein the thinnest region of the weak part is located at least on both sides of the weak part in the width direction of the first wall part.

[0006] In the above technical solution, the base material of the pressure relief mechanism is iron, which can effectively improve the structural strength of the pressure relief mechanism, reduce the risk of early valve pressure relief of the pressure relief mechanism, and is beneficial to improving the service life and reliability of the battery cell. The thinnest region of the weak part is located at least on both sides of the weak part in the width direction of the first wall part. When the pressure inside the shell reaches the threshold value, the thinnest region of the weak part cracks first, that is, both sides of the weak part in the width direction of the first wall part crack first. In this way, even if the pressure relief area defined by the weak part is not completely opened, the high-temperature gas sprayed out is not easy to diffuse along the width direction of the first wall part, and when diffusing along other directions, the high-temperature gas is not easy to diffuse to another battery cell adjacent to it, and is not easy to cause thermal runaway of another battery cell, which is beneficial to improving the reliability of the battery device.

[0007] As an optional technical solution of the embodiments of the present application, the weak part is in the form of a closed ring, the difference between the minimum thicknesses of the cross sections of the weak part at any two positions in the extension direction of the weak part is less than 0.01 mm, and the cross sections are perpendicular to the extension direction.

[0008] In the technical solution, the minimum thickness of the cross section of the weak part at any two positions in the extension direction of the weak part is less than 0.01 mm, that is, the minimum thickness of the weak part at any two positions in the extension direction of the weak part is substantially the same. When the pressure inside the shell reaches the threshold value, the pressure relief mechanism can be cracked along the entire circumference of the weak part, so that the pressure relief area defined by the weak part can be separated from the pressure relief mechanism, the pressure relief area is not easy to hang on the pressure relief mechanism, and the risk of high-temperature gas injection to the adjacent battery cell is reduced, which is beneficial to improve the reliability of the battery cell.

[0009] As an optional technical solution of the embodiment, the minimum thickness of the cross section of the weak part at any two positions in the extension direction of the weak part is equal.

[0010] In the technical solution, the minimum thickness of the cross section of the weak part at any two positions in the extension direction of the weak part is equal. When the pressure inside the shell reaches the threshold value, the pressure relief mechanism can be cracked along the entire circumference of the weak part, so that the pressure relief area defined by the weak part can be separated from the pressure relief mechanism, the pressure relief area is not easy to hang on the pressure relief mechanism, and the risk of high-temperature gas injection to the adjacent battery cell is reduced, which is beneficial to improve the reliability of the battery cell.

[0011] As an optional technical solution of the embodiment, the minimum thickness of the weak part is H1, and 0.01 mm≤H1≤0.2 mm.

[0012] In the technical solution, when H1≥0.01 mm, the thickness of the weak part is large, and the weak part is not easy to be cracked in advance due to the change of the pressure inside the battery cell or the external impact, which is beneficial to reduce the risk of the destruction of the weak part in advance and improve the service life and reliability of the battery cell. When H1≤0.2 mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time to release pressure when the battery cell is out of control, which is beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 0.01 mm≤H1≤0.2 mm, the service life of the battery cell and the timeliness of the pressure relief can be considered.

[0013] As an optional technical solution of the embodiment, 0.01 mm≤H1≤0.15 mm.

[0014] In the technical solution, when H1 is greater than or equal to 0.01 mm, the thickness of the weak part is relatively large, the weak part is not prone to be broken in advance due to the pressure change inside the battery monomer or external impact, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life and reliability of the battery monomer. When H1 is less than or equal to 0.15 mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can open the pressure relief more timely when the battery monomer is out of control, which is more beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 0.01 mm≤H1≤0.15 mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0015] As an optional technical solution of the embodiment of the application, the weak part is in a closed ring shape, the weak part comprises a first weak section and a second weak section connected in a head-to-tail manner, the thickness of the second weak section is greater than that of the first weak section, and the second weak section is located on one side of the weak part in the length direction of the first wall part.

[0016] In the technical solution, by arranging the second weak section, the strength of the pressure relief mechanism at the position of the second weak section is weakened, so that the pressure relief area is more likely to be turned over and opened under the action of the internal gas pressure of the battery monomer. Not only can the opening probability of the pressure relief area be improved, but also the opening speed of the pressure relief area can be improved to achieve rapid pressure relief, reduce the risk of explosion and fire of the battery monomer, and improve the reliability of the battery monomer. By arranging the second weak section on one side of the weak part in the length direction of the first wall part, even if the pressure relief area is not completely opened, the high-temperature gas sprayed out will diffuse towards the length direction of the first wall part under the action of the pressure relief area. When diffusing along the length direction of the first wall part, the path to the adjacent battery monomer is farther, that is, the high-temperature gas sprayed out is less likely to diffuse to the adjacent battery monomer, which is less likely to cause thermal runaway of the adjacent battery monomer, and the reliability of the battery device can be improved.

[0017] As an optional technical solution of the embodiment of the application, the second weak section extends along a straight line trajectory.

[0018] In the technical solution, the second weak section extends along a straight line trajectory, which is convenient to manufacture and can open the pressure relief more quickly when the battery monomer is pressure relieved.

[0019] As an optional technical solution of the embodiment of the application, the second weak section extends along an arc trajectory.

[0020] In the technical solution, the second weak section extends along an arc trajectory, which is beneficial to reduce stress concentration.

[0021] As an optional technical solution of the embodiment of the present application, the thickness of the first weak section is H1, and the thickness of the second weak section is H2, and the following is met: H2-H1 >= 0.01mm, and optionally, H2-H1 >= 0.05mm.

[0022] In the above technical solution, when H2-H1 >= 0.01mm, the thickness of the second weak section is quite different from the thickness of the first weak section, and the second weak section is not easy to crack when the battery cell is pressure released, so that the second weak section can better guide the turning of the pressure release area.

[0023] When H2-H1 >= 0.05mm, the thickness of the second weak section is more different from the thickness of the first weak section, and the second weak section is more not easy to crack when the battery cell is pressure released, so that the second weak section can better guide the turning of the pressure release area.

[0024] As an optional technical solution of the embodiment of the present application, 0.05mm <= H2 <= 0.4mm.

[0025] In the above technical solution, when H2 >= 0.05mm, the thickness of the second weak section is large, which can reduce the risk of the second weak section cracking in advance due to the change of the pressure inside the battery cell or external impact, and is beneficial to improve the reliability of the battery cell. When H2 <= 0.4mm, the second thickness is not too large, thereby being beneficial to reduce the resistance of the turning of the pressure release area, facilitating the rapid turning of the pressure release area to open, and being beneficial to improve the timeliness of the pressure release of the battery cell. Therefore, when 0.05mm <= H2 <= 0.4mm, the thickness of the second weak section is moderate, the second weak section is neither easy to crack due to the change of the air pressure inside the battery cell, nor easy to facilitate the rapid turning of the pressure release area to open, and is beneficial to improve the timeliness of the pressure release of the battery cell.

[0026] As an optional technical solution of the embodiment of the present application, the first weak section includes a first section, a second section and a third section, the first section, the second section, the third section and the second weak section are connected in sequence, and the first section and the third section are located on both sides of the weak section in the width direction of the first wall part.

[0027] In the above technical solution, the first section and the third section are located on both sides of the weak section in the width direction of the first wall part, so that the line connecting the two ends of the second weak section is substantially parallel to the width direction of the first wall part. When the battery cell is pressure released, even if the pressure release area is not completely opened, the high-temperature gas sprayed will move substantially along the length direction of the first wall part after being bounced back through the pressure release area. The distance between the battery cell and the battery cell adjacent to it along the length direction of the first wall part is large, so the high-temperature gas sprayed is not easy to be bounced to another battery cell adjacent to it, and is not easy to cause thermal runaway of another battery cell, which is beneficial to improve the reliability of the battery cell.

[0028] As an optional technical solution of the embodiment of the application, the first segment and / or the third segment extends along a straight line trajectory.

[0029] In the above technical solution, by making the first segment and / or the third segment extend along a straight line trajectory, it is easier to split along the first segment and the third segment when the battery cell is depressurized, which can improve the opening speed of the pressure relief area and achieve rapid pressure relief.

[0030] As an optional technical solution of the embodiment of the application, the weak part is in the shape of an opening, and the opening end of the weak part is located on one side of the weak part in the length direction of the first wall part.

[0031] In the above technical solution, by making the opening end of the weak part located on one side of the weak part in the length direction of the first wall part, when the battery cell is depressurized, the pressure relief area is turned open around the opening end. Even if the pressure relief area is not completely opened, the high-temperature gas sprayed out will diffuse towards the length direction of the first wall part under the action of the pressure relief area, and when diffusing along the length direction of the first wall part, it is more difficult for the high-temperature gas to diffuse to the other battery cell adjacent to it, which is not easy to cause thermal runaway of the other battery cell, which is beneficial to improve the reliability of the battery device.

[0032] As an optional technical solution of the embodiment of the application, the material of the pressure relief mechanism is 304 stainless steel, 305 stainless steel or 316 stainless steel.

[0033] In the above technical solution, 304 stainless steel, 305 stainless steel and 316 stainless steel have the advantages of corrosion resistance, high temperature resistance, good processing performance, etc. The pressure relief mechanism made of 304 stainless steel, 305 stainless steel or 316 stainless steel has high strength, which can reduce the risk of deformation of the pressure relief mechanism under stress, which is beneficial to reduce the risk of early valve pressure relief of the pressure relief mechanism, improve the service life and reliability of the battery cell, and improve the consistency of the ignition pressure of multiple battery cells.

[0034] As an optional technical solution of the embodiment of the application, the battery cell includes an electrode assembly, which is accommodated in the shell; the electrode assembly includes a positive electrode sheet, which includes a positive electrode active material capable of reversible extraction-embedding metal ions, and the positive electrode active material includes a nickel-containing element compound.

[0035] In the aforementioned technical solutions, when the positive electrode active material of the positive electrode sheet includes a nickel-containing compound, it can effectively increase the energy density and cycle life of the battery cell. However, it also increases the gas generated during the use of the battery cell, especially in the event of thermal runaway. The rapid increase in internal temperature and the generation of a large amount of gas in the battery cell can easily trigger thermal runaway in adjacent cells. Therefore, this application offers better results for battery cells where the positive electrode active material includes a nickel-containing compound.

[0036] As an optional technical solution in this application embodiment, the nickel-containing compound includes a layered lithium-containing transition metal oxide, wherein the molar amount of nickel in the layered lithium-containing transition metal oxide accounts for more than 50% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide.

[0037] In the above technical solution, by making the molar amount of nickel in the layered lithium-containing transition metal oxide account for more than 50% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide, the energy density and cycle life of the battery cell can be effectively improved.

[0038] As an optional technical solution in this application embodiment, the molar amount of nickel in the layered lithium-containing transition metal oxide accounts for more than 80% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide.

[0039] In the above technical solution, by making the molar amount of nickel in the layered lithium-containing transition metal oxide account for more than 80% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide, the energy density and cycle life of the battery cell can be improved.

[0040] As an optional technical solution in this application embodiment, the layered lithium-containing transition metal oxide includes Li a Ni b Co c M d O e A f Wherein, 0 < a ≤ 1.2, 0.5 ≤ b < 1, optionally, 0.9 ≤ b < 1; 0 < c < 1; 0 < d < 1; 1 ≤ e ≤ 2; 0 ≤ f ≤ 1, M includes but is not limited to one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A includes but is not limited to one or more of N, F, S and Cl, which can improve the energy density of battery cells.

[0041] As an optional technical solution of the embodiment of the present application, the pressure relief mechanism comprises a raised portion and a connecting portion, the raised portion is located in the area surrounded by the weak portion, the connecting portion is located outside the weak portion and is arranged on the first wall portion, and the raised portion is a raised structure raised in a direction away from the inside of the shell.

[0042] In the above technical solution, the existing pressure relief mechanism will gradually arch away from the electrode assembly under the action of the internal pressure of the battery monomer when pressure relief, and then open under the action of the internal pressure of the battery monomer after arching. In the embodiment of the present application, the raised portion of the pressure relief mechanism is raised in a direction away from the electrode assembly, and the raised portion forms a pre-deformation on the inside of the weak portion, thereby facilitating the opening of the weak portion for pressure relief. In this way, under the same burst pressure, the thickness of the weak portion can be larger, and the weak portion is not easy to crack prematurely due to changes in the internal pressure of the battery monomer or external impact during normal use of the battery monomer, which is conducive to reducing the risk of premature destruction of the weak portion and improving the service life of the battery monomer. Compared with the aluminum material explosion-proof valve in the prior art, the thickness of the weak portion of the pressure relief mechanism provided in the embodiment of the present application is smaller, and a slight change in the thickness of the weak portion during manufacturing will result in a large change in the burst pressure of the battery monomer. By providing the raised portion, the thickness of the weak portion can be increased under the same burst pressure, and the larger the thickness of the weak portion, the easier it is to manufacture, thereby facilitating the consistency of the burst pressure of multiple battery monomers. Furthermore, when the battery monomer expands, the first wall portion is deformed under stress, and the raised portion can be stretched under the action of external force, thereby reducing the pulling of the weak portion by external force, reducing the risk of premature destruction of the weak portion, and improving the service life of the battery monomer.

[0043] As an optional technical solution of the embodiment of the present application, the boundary of the raised portion is at least partially adjacent to the boundary of the weak portion.

[0044] In the above technical solution, by making the boundary of the raised portion at least partially adjacent to the boundary of the weak portion, the raised portion can directly pull the weak portion through the adjacent part when the battery monomer is pressure relieved, so that the part of the weak portion adjacent to the boundary of the raised portion receives greater shear force, thereby facilitating the opening of the weak portion for pressure relief. In the same burst pressure, the thickness of the weak portion can be larger, and the weak portion is not easy to crack prematurely due to changes in the internal pressure of the battery monomer or external impact during normal use of the battery monomer, which is conducive to reducing the risk of premature destruction of the weak portion and improving the service life and reliability of the battery monomer. In addition, the larger the thickness of the weak portion, the easier it is to manufacture, thereby facilitating the consistency of the burst pressure of multiple battery monomers.

[0045] As an optional technical solution of the embodiment of the present application, the boundary of the raised portion is completely adjacent to the boundary of the weak portion.

[0046] In the technical solution, the boundary of the raised portion is completely adjacent to the boundary of the weak portion. When the battery cell is depressurized, the raised portion can directly pull the weak portion, so that the weak portion is subjected to greater shear force, thereby facilitating the opening of the weak portion for pressure relief. Under the same burst pressure, the thickness of the weak portion can be greater. When the battery cell is in normal use, the weak portion is less likely to be prematurely cracked due to changes in the internal pressure of the battery cell or external impact, thereby reducing the risk of premature damage to the weak portion and improving the service life and reliability of the battery cell. In addition, the greater the thickness of the weak portion, the easier it is to manufacture, thereby improving the consistency of the burst pressure of the plurality of battery cells.

[0047] As an optional technical solution of the embodiment, the minimum thickness of the weak portion is H1, and 0.01mm≤H1≤0.2mm is satisfied.

[0048] In the technical solution, when H1≥0.01mm, the thickness of the weak portion is greater, and the weak portion is less likely to be prematurely cracked due to changes in the internal pressure of the battery cell or external impact, thereby reducing the risk of premature damage to the weak portion and improving the service life and reliability of the battery cell. When H1≤0.2mm, the thickness of the weak portion is not too large, so that the pressure relief mechanism can be opened in time for pressure relief when the battery cell is in thermal runaway, thereby improving the timeliness of pressure relief of the pressure relief mechanism. Therefore, when 0.01mm≤H1≤0.2mm, the service life of the battery cell and the timeliness of pressure relief can be considered.

[0049] As an optional technical solution of the embodiment, the area enclosed by the weak portion is a pressure relief area, and the projection area of the pressure relief area along the thickness direction of the first wall portion is S; wherein, 100mm 2 ≤450mm 2 , and 0.010mm≤H1≤0.160mm; or, 350mm 2 ≤S≤850mm 2 , and 0.015mm≤H1≤0.170mm; or, 750mm 2 ≤S≤1250mm 2 , and 0.020mm≤H1≤0.180mm; or, 1150mm 2 ≤S≤1650mm 2 , and 0.025mm≤H1≤0.190mm; or, 1550mm 2 ≤S≤2100mm 2 , and 0.030mm≤H1≤0.200mm.

[0050] In the technical solution, when the projection area of the pressure relief area is large, the pressure relief area is more easily affected by the internal pressure to cause the weak part to crack, therefore, when the projection area of the pressure relief area is increased, in order to ensure the same blasting pressure, the thickness of the weak part can be increased. When 100mm 2 ≤S≤450mm 2 , and H1≥0.010mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the internal pressure of the battery monomer or external impact, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery monomer. When 100mm 2 ≤S≤450mm 2 , and H1≤0.160mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery monomer is out of control, which is beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 100mm 2 ≤S≤450mm 2 , and 0.010mm≤H1≤0.160mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0051] When 350mm 2 ≤S≤850mm 2 , and H1≥0.015mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the internal pressure of the battery monomer or external impact, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery monomer. When 350mm 2 ≤S≤850mm 2 , and H1≤0.170mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery monomer is out of control, which is beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 350mm 2 ≤S≤850mm 2 , and 0.015mm≤H1≤0.170mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0052] When 750mm 2 ≤S≤1250mm 2 , and H1≥0.020mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the internal pressure of the battery monomer or external impact, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery monomer. When 750mm 2 ≤S≤1250mm 2 , and H1≤0.180mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery monomer is out of control, which is beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 750mm2 ≤S≤1250mm 2 , and 0.020mm≤H1≤0.180mm, the service life of the battery monomer and the timeliness of pressure relief can be considered.

[0053] When 1150mm 2 ≤S≤1650mm 2 , and H1≥0.025mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the pressure inside the battery monomer or the external impact, which is beneficial to reduce the risk of the destruction of the weak part in advance and improve the service life of the battery monomer. When 1150mm 2 ≤S≤1650mm 2 , and H1≤0.190mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery monomer is out of control, which is beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 1550mm 2 ≤S≤2100mm 2 , and 0.025mm≤H1≤0.190mm, the service life of the battery monomer and the timeliness of pressure relief can be considered.

[0054] When 1550mm 2 ≤S≤2100mm 2 , and H1≥0.030mm, the thickness of the weak part is large, and the weak part is not easy to crack in advance due to the change of the pressure inside the battery monomer or the external impact, which is beneficial to reduce the risk of the destruction of the weak part in advance and improve the service life of the battery monomer. When 1550mm 2 ≤S≤2100mm 2 , and H1≤0.200mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened in time when the battery monomer is out of control, which is beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism. Therefore, when 1550mm 2 ≤S≤2100mm 2 , and 0.030mm≤H1≤0.200mm, the service life of the battery monomer and the timeliness of pressure relief can be considered.

[0055] As an optional technical solution of the embodiment of the application, 100mm 2 ≤S≤450mm 2 , and 0.020mm≤H1≤0.160mm; or, 350mm 2 ≤S≤850mm 2 , and 0.025mm≤H1≤0.170mm; or, 750mm 2 ≤S≤1250mm 2 , and 0.030mm≤H1≤0.180mm; or, 1150mm2 ≤S≤1650mm 2 , and 0.035mm≤H1≤0.190mm; or, 1550mm 2 ≤S≤2100mm 2 , and 0.040mm≤H1≤0.200mm.

[0056] In the above technical solutions, when 100mm 2 ≤S≤450mm 2 , and H1≥0.020mm, the thickness of the weak part is larger, the weak part is less likely to be cracked in advance due to the change of the pressure inside the battery monomer or external impact, and it is more conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery monomer. When 100mm 2 ≤S≤450mm 2 , and H1≤0.160mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened more timely when the battery monomer is out of control, and it is more conducive to improving the timeliness of the pressure relief mechanism. Therefore, when 100mm 2 ≤S≤450mm 2 , and 0.020mm≤H1≤0.160mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0057] When 350mm 2 ≤S≤850mm 2 , and H1≥0.025mm, the thickness of the weak part is larger, the weak part is less likely to be cracked in advance due to the change of the pressure inside the battery monomer or external impact, and it is more conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery monomer. When 350mm 2 ≤S≤850mm 2 , and H1≤0.170mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened more timely when the battery monomer is out of control, and it is more conducive to improving the timeliness of the pressure relief mechanism. Therefore, when 350mm 2 ≤S≤850mm 2 , and 0.025mm≤H1≤0.170mm, the service life and the timeliness of the pressure relief of the battery monomer can be considered.

[0058] When 750mm 2 ≤S≤1250mm 2 , and H1≥0.030mm, the thickness of the weak part is larger, the weak part is less likely to be cracked in advance due to the change of the pressure inside the battery monomer or external impact, and it is more conducive to reducing the risk of the weak part being damaged in advance and improving the service life of the battery monomer. When 750mm 2 ≤S≤1250mm2 When 750mm 2 ≤S≤1250mm 2 , and 0.030mm≤H1≤0.180mm, the service life of the battery cell and the timeliness of pressure relief can be better balanced.

[0059] When 1150mm 2 ≤S≤1650mm 2 , and H1≥0.035mm, the thickness of the weak part is larger, and the weak part is less likely to be prematurely cracked due to changes in internal pressure of the battery cell or external impact, which is more conducive to reducing the risk of the weak part being prematurely damaged and more conducive to improving the service life of the battery cell. When 1150mm 2 ≤S≤1650mm 2 , and H1≤0.190mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened more timely when the battery cell is out of control, which is more conducive to improving the timeliness of pressure relief of the pressure relief mechanism. Therefore, when 1550mm 2 ≤S≤2100mm 2 , and 0.035mm≤H1≤0.190mm, the service life of the battery cell and the timeliness of pressure relief can be better balanced.

[0060] When 1550mm 2 ≤S≤2100mm 2 , and H1≥0.040mm, the thickness of the weak part is larger, and the weak part is less likely to be prematurely cracked due to changes in internal pressure of the battery cell or external impact, which is more conducive to reducing the risk of the weak part being prematurely damaged and more conducive to improving the service life of the battery cell. When 1550mm 2 ≤S≤2100mm 2 , and H1≤0.200mm, the thickness of the weak part is not too large, so that the pressure relief mechanism can be opened more timely when the battery cell is out of control, which is more conducive to improving the timeliness of pressure relief of the pressure relief mechanism. Therefore, when 1550mm 2 ≤S≤2100mm 2 , and 0.040mm≤H1≤0.200mm, the service life of the battery cell and the timeliness of pressure relief can be better balanced.

[0061] As an optional technical solution of the embodiment of the application, the protrusion height of the protrusion part is H3, which satisfies: 0.2mm≤H3≤4.9mm.

[0062] In the technical solution, when H3 is greater than or equal to 0.2 mm, the bulging height of the bulging part is relatively high, so the deformation of the bulging part is relatively obvious, and under the same blasting pressure, the thickness of the weak part is relatively large, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery cell. When H3 is less than or equal to 4.9 mm, the bulging height of the bulging part is not too large, on the one hand, it is beneficial to reduce the occupation of the internal space of the battery or the battery cell and improve the energy density of the battery or the battery cell, and on the other hand, it is beneficial to reduce the risk of interference between the bulging part and other components. Therefore, when 0.2 mm≤H3≤4.9 mm, the service life and the energy density of the battery cell can be considered, and the risk of interference between the bulging part and other components can be reduced.

[0063] As an optional technical solution of the embodiment of the application, 0.3 mm≤H3≤3 mm.

[0064] In the technical solution, when H3 is greater than or equal to 0.3 mm, the bulging height of the bulging part is relatively high, so the deformation of the bulging part is more obvious, and under the same blasting pressure, the thickness of the weak part can be larger, which is beneficial to reduce the risk of the weak part being damaged in advance and improve the service life of the battery cell. When H3 is less than or equal to 3 mm, the bulging height of the bulging part is not too large, on the one hand, it is beneficial to reduce the occupation of the internal space of the battery or the battery cell and improve the energy density of the battery or the battery cell, and on the other hand, it is beneficial to reduce the risk of interference between the bulging part and other components. Therefore, when 0.3 mm≤H3≤3 mm, the service life and the energy density of the battery cell can be considered, and the risk of interference between the bulging part and other components can be reduced.

[0065] As an optional technical solution of the embodiment of the application, the connecting part is at least partially bulged in a direction facing the inside of the shell, and the weak part is connected to the part of the connecting part closest to the inside of the shell.

[0066] In the technical solution, by making the connecting part at least partially bulged in a direction away from the electrode assembly and connecting the weak part to the part of the connecting part farthest away from the electrode assembly, the connecting part is connected to the first wall part without affecting the weak part, which is beneficial to maintain the performance of the weak part and improve the service life of the battery cell.

[0067] As an optional technical solution of the embodiment of the application, the bulging height of the connecting part is H4, and 0.2 mm≤H4≤7 mm, and optionally, 0.2 mm≤H4≤5 mm.

[0068] In the technical solution, when H4 is greater than or equal to 0.2 mm, the height of the connection portion is relatively large, thereby facilitating reduction of the height of the raised portion beyond the surface of the connection portion farthest from the electrode assembly, reduction of the occupation of the battery monomer or the internal space of the battery, and improvement of the energy density of the battery monomer or the battery. When H4 is less than or equal to 7 mm, the height of the connection portion is not excessively large, thereby facilitating reduction of the manufacturing difficulty and saving of the manufacturing cost. Therefore, when 0.2 mm≤H4≤7 mm, the occupation of the raised portion to the battery monomer or the internal space of the battery can be effectively reduced, and the manufacturing cost of the battery monomer can be reduced.

[0069] When H4 is greater than or equal to 0.2 mm, the height of the connection portion is relatively large, thereby facilitating reduction of the height of the raised portion beyond the surface of the connection portion farthest from the electrode assembly, reduction of the occupation of the battery monomer or the internal space of the battery, and improvement of the energy density of the battery monomer or the battery. When H4 is less than or equal to 5 mm, the height of the connection portion is not excessively large, thereby more facilitating reduction of the manufacturing difficulty and saving of the manufacturing cost. Therefore, when 0.2 mm≤H4≤5 mm, the occupation of the raised portion to the battery monomer or the internal space of the battery can be effectively reduced, and the manufacturing cost of the battery monomer can be reduced.

[0070] As an optional technical solution of the embodiment, the connection portion comprises a first part and a second part, the first part is connected to the first wall portion, the second part is raised in a direction facing the inside of the shell relative to the first part, and the weak portion is connected to the second part; the first part is arranged around the outside of the second part, and the width of the first part is D1, which satisfies 0.05 mm≤D1≤0.5 mm.

[0071] In the technical solution, when D1 is greater than or equal to 0.05 mm, the width of the first part is relatively large, thereby facilitating connection of the first part to the first wall portion. When D1 is less than or equal to 0.5 mm, the width of the first part is not excessively large, thereby enabling the pressure relief area defined by the weak portion to be relatively large, and facilitating improvement of the timeliness of pressure relief of the battery monomer. Therefore, when 0.05 mm≤D1≤0.5 mm, the first part can be conveniently connected to the first wall portion, and the battery monomer can be rapidly pressure relieved.

[0072] As an optional technical solution of the embodiment, the pressure relief mechanism comprises a connection area, the connection area directly connects the connection portion and the raised portion, and the weak portion is arranged in the connection area; the width of the connection area is D2, which satisfies 0.3 mm≤D2≤2 mm.

[0073] In the technical solution, when D2 is greater than or equal to 0.3 mm, the width of the connecting area is relatively large, and it is easier to process the weak part in the connecting area. When D2 is less than or equal to 2 mm, the width of the connecting area is too large, and the connecting area is not easy to process and manufacture. Therefore, when 0.3 mm≤D2≤2 mm, it is beneficial to simplify production and reduce production cost.

[0074] As an optional technical solution of the embodiment, the pressure relief mechanism is provided with a pressure relief groove, and the pressure relief mechanism and the pressure relief groove correspond to the weak part.

[0075] In the technical solution, the weak part is formed on the pressure relief mechanism by opening the pressure relief groove on the pressure relief mechanism. When the battery cell is relieved, the pressure relief mechanism is cracked along at least part of the weak part, which is simple, convenient and low in cost.

[0076] As an optional technical solution of the embodiment, the width of the slot of the pressure relief groove is D3, and 0.02 mm≤D3≤0.8 mm, and optionally, 0.03 mm≤D3≤0.6 mm.

[0077] In the technical solution, when D3 is greater than or equal to 0.02 mm, the width of the slot of the pressure relief groove is relatively large, the width of the weak part is relatively large, the risk of the weak part being cracked due to the change of the internal gas pressure of the battery cell is reduced, and the reliability of the battery cell is improved. When D3 is less than or equal to 0.8 mm, the width of the slot of the pressure relief groove is not too large, and the weak part is timely cracked when the battery cell is relieved, and the timeliness of the relief of the battery cell is improved. Therefore, when 0.02 mm≤D3≤0.8 mm, the width of the slot of the pressure relief groove is moderate, the weak part is neither easy to be cracked due to the change of the internal gas pressure of the battery cell nor timely cracked when the battery cell is relieved, and the timeliness of the relief of the battery cell is improved.

[0078] When D3 is greater than or equal to 0.03 mm, the width of the slot of the pressure relief groove is larger, the width of the weak part is larger, the risk of the weak part being cracked due to the change of the internal gas pressure of the battery cell is reduced, and the reliability of the battery cell is improved. When D3 is less than or equal to 0.6 mm, the width of the slot of the pressure relief groove is not too large, and the weak part is timely cracked when the battery cell is relieved, and the timeliness of the relief of the battery cell is improved. Therefore, when 0.03 mm≤D3≤0.6 mm, the width of the slot of the pressure relief groove is more moderate, the weak part is neither easy to be cracked due to the change of the internal gas pressure of the battery cell nor timely cracked when the battery cell is relieved, and the timeliness of the relief of the battery cell is improved.

[0079] As an optional technical solution of the embodiment, the thickness of the pressure relief mechanism is H5, and 0.05 mm≤H5≤0.5 mm, and optionally, 0.05 mm≤H5≤0.3 mm.

[0080] In the technical solution, when H5 is greater than or equal to 0.05 mm, the thickness of the pressure relief mechanism is relatively large, the pressure relief mechanism has high structural strength, the risk of deformation of the pressure relief mechanism under stress can be reduced, and the service life and reliability of the battery monomer can be improved. When H5 is less than or equal to 0.5 mm, the thickness of the pressure relief mechanism is not too large, and the manufacturing cost of the battery monomer can be controlled. Therefore, when 0.05 mm≤H5≤0.5 mm, the service life, reliability and manufacturing cost of the battery monomer can be considered.

[0081] When H5 is greater than or equal to 0.05 mm, the thickness of the pressure relief mechanism is relatively large, the pressure relief mechanism has high structural strength, the risk of deformation of the pressure relief mechanism under stress can be reduced, and the service life and reliability of the battery monomer can be improved. When H5 is less than or equal to 0.3 mm, the thickness of the pressure relief mechanism is not too large, and the manufacturing cost of the battery monomer can be controlled. Therefore, when 0.05 mm≤H5≤0.3 mm, the service life, reliability and manufacturing cost of the battery monomer can be considered.

[0082] As an optional technical solution of the embodiment of the application, the pressure relief mechanism is arranged separately from the first wall part, the first wall part is provided with a pressure relief hole, and the pressure relief mechanism is mounted on the first wall part and covers the pressure relief hole.

[0083] In the technical solution, the pressure relief mechanism is arranged separately from the first wall part and mounted on the first wall part, so as to facilitate processing and manufacturing.

[0084] As an optional technical solution of the embodiment of the application, the base material of the first wall part is iron, and the pressure relief mechanism is welded to the first wall part.

[0085] In the technical solution, the base material of the pressure relief mechanism and the first wall part is iron. On the one hand, the structural strength of the first wall part and the pressure relief mechanism can be effectively improved, the risk of deformation of the first wall part and the pressure relief mechanism under stress can be reduced, the risk of early valve pressure relief of the pressure relief mechanism can be reduced, the service life and reliability of the battery monomer can be improved. On the other hand, the pressure relief mechanism and the first wall part are easy to weld, the phenomenon of welding cracks of the pressure relief mechanism and the end cover can be reduced, the risk of liquid leakage of the battery monomer can be reduced, and the reliability of the battery monomer can be improved.

[0086] As an optional technical solution of the embodiment of the application, the pressure relief mechanism is integrally formed with the first wall part.

[0087] In the technical solution, the pressure relief mechanism is integrally formed with the first wall part, without the need for additional welding or bonding processes, and the risk of liquid leakage of the pressure relief mechanism can be reduced. Moreover, during production, the initiation pressure of the processed battery monomers is easy to be consistent.

[0088] In a second aspect, the embodiments of the present application further provide a battery device, which comprises the battery cell described above.

[0089] In a third aspect, the embodiments of the present application further provide a power consuming device, which comprises the battery cell described above, and the battery cell is used to provide electric energy for the power consuming device. BRIEF DESCRIPTION OF DRAWINGS

[0090] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation to the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0091] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application;

[0092] FIG. 2 is an exploded view of a battery device according to some embodiments of the present application;

[0093] FIG. 3 is a structural schematic diagram of a battery cell according to some embodiments of the present application;

[0094] FIG. 4 is an exploded view of the battery cell according to some embodiments of the present application;

[0095] FIG. 5 is a top view of a first wall according to some embodiments of the present application;

[0096] FIG. 6 is a sectional view of the position A-A in FIG. 5;

[0097] FIG. 7 is a structural schematic diagram of a pressure relief mechanism according to some embodiments of the present application;

[0098] FIG. 8 is a top view of the pressure relief mechanism according to some embodiments of the present application;

[0099] FIG. 9 is a sectional view of the position B-B in FIG. 8;

[0100] FIG. 10 is a top view of the pressure relief mechanism according to some other embodiments of the present application;

[0101] FIG. 11 is a sectional view of the pressure relief mechanism according to some other embodiments of the present application;

[0102] FIG. 12 is a top view of the pressure relief mechanism according to some other embodiments of the present application.

[0103] Icon: 10 - case; 11 - first case body; 12 - second case body; 20 - battery cell; 21 - housing; 211 - case; 212 - end cover; 213 - first wall portion; 2131 - pressure relief hole; 23 - electrode assembly; 231 - main body; 232 - tab; 24 - pressure relief mechanism; 241 - connecting portion; 2411 - first portion; 2412 - second portion; 2421 - connecting region; 2421a - weak portion; 24212 - first weak section; 24212a - first section; 24212b - second section; 24212c - third section; 24213 - second weak section; 2422 - pressure relief region; 24221 - protrusion; 245 - pressure relief groove; 25 - electrode terminal; 26 - protection member; 27 - insulation member; 100 - battery device; 200 - controller; 300 - motor; 1000 - vehicle. DETAILED DESCRIPTION

[0104] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0105] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion. The terms "first", "second" and the like in the specification and claims of the present application and the above description of drawings are used to distinguish different objects, not to describe a particular order or primary and secondary relationship.

[0106] In the present application, the phrase "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment can be included in at least one embodiment of the present application. The phrase appears at various places in the specification does not necessarily refer to the same embodiment, nor is it mutually exclusive or alternative to other embodiments.

[0107] In the description of the present application, it should be noted that unless specifically defined and limited otherwise, the terms "mount", "connected", "connection", "attach" should be broadly interpreted, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be directly connected, or indirectly connected through an intermediate medium; can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0108] The term "and / or" in the present application is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the present application generally represents that the front and rear associated objects have an "or" relationship.

[0109] In the embodiments of the present application, the same reference signs represent the same parts, and for the sake of brevity, the detailed description of the same parts is omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, and the overall thickness, length, width and other dimensions of the integrated device are only exemplary and should not constitute any limitation on the present application.

[0110] "Multiple" appearing in the present application means two or more (including two).

[0111] In the embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging.

[0112] The battery cell includes but is not limited to lithium ion battery, sodium ion battery, sodium lithium ion battery, lithium metal battery, sodium metal battery, lithium sulfur battery, magnesium ion battery, nickel hydrogen battery, nickel cadmium battery, lead-acid battery, etc.

[0113] The battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of the battery cell, active ions (such as lithium ions) are embedded and extracted between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode, which can reduce the risk of short circuit of the positive and negative electrodes, and at the same time allow the active ions to pass through.

[0114] In some embodiments, the positive electrode can be a positive electrode sheet, which can include a positive electrode current collector and a positive electrode active material arranged on at least one surface of the positive electrode current collector.

[0115] As an example, the positive electrode current collector has two opposite surfaces in its own thickness direction, and the positive electrode active material is arranged on any one or both of the two opposite surfaces of the positive electrode current collector.

[0116] As an example, the positive electrode current collector can employ a metal foil or a composite current collector. For example, as the metal foil, aluminum subjected to silver plating on the surface, stainless steel subjected to silver plating on the surface, stainless steel, copper, aluminum, nickel, a carbon electrode, carbon, nickel, or titanium, or the like can be employed. The composite current collector can include a high molecular material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, or the like) on a high molecular material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, or the like).

[0117] As an example, the positive electrode active material can include at least one of a lithium-containing phosphate, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material of a battery cell can also be used. These positive electrode active materials can be used alone only one or two or more can be used in combination. Among them, examples of the lithium-containing phosphate can include, but are not limited to, at least one of lithium iron phosphate (such as LiFeP04 (which can also be referred to simply as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnP04), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon. Examples of the lithium transition metal oxide can include, but are not limited to, lithium cobalt oxide (such as LiCo02), lithium nickel oxide (such as LiNi02), lithium manganese oxide (such as LiMn02, LiMn204), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be referred to simply as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be referred to simply as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be referred to simply as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be referred to simply as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be referred to simply as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05O2) and modified compounds thereof, etc.

[0118] In some embodiments, the positive electrode can employ a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. When the foamed metal is employed as the positive electrode, the foamed metal surface can be free of the positive electrode active material, or can be provided with the positive electrode active material. As an example, the foamed metal can be filled or / and deposited with a lithium source material, potassium metal, or sodium metal. The lithium source material can be lithium metal and / or a lithium-rich material.

[0119] In some embodiments, the negative electrode can be a negative electrode sheet, which can include a negative electrode current collector.

[0120] As an example, the negative electrode current collector can employ a metal foil, a foamed metal, or a composite current collector. For example, as the metal foil, aluminum with a silver-plated surface, stainless steel with a silver-plated surface, stainless steel, copper, aluminum, nickel, a carbon electrode, carbon, nickel, or titanium, etc. can be employed. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, etc. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0121] As an example, the negative electrode sheet can include a negative electrode current collector and a negative electrode active material provided on at least one surface of the negative electrode current collector.

[0122] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode active material is provided on either one or both of the two opposite surfaces of the negative electrode current collector.

[0123] As an example, the negative electrode active material can employ a negative electrode active material known in the art for use in a battery cell. As an example, the negative electrode active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, a silicon-based material, a tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can be selected from at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode active material for a battery cell can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0124] In some embodiments, the material of the positive electrode current collector can be aluminum, and the material of the negative electrode current collector can be copper.

[0125] In some embodiments, the separator is a separator film. The separator film can be any porous structure separator film known to have good chemical stability and mechanical stability.

[0126] As an example, the material of the separator film can include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single layer film or a multi-layer composite film. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different. The separator can be a separate component between the positive and negative electrodes or can be attached to the surface of the positive and negative electrodes.

[0127] In some embodiments, the battery cell further includes an electrolyte that functions to conduct ions between the positive and negative electrodes. The electrolyte can be in a liquid state, a gel state, or a solid state. Among them, the liquid electrolyte includes an electrolyte salt and a solvent.

[0128] In some embodiments, the electrolyte salt can include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobisoxalate borate, lithium bisoxalate borate, lithium difluorobisoxalate phosphate, and lithium tetrafluorobisoxalate phosphate.

[0129] In some embodiments, the solvent can include at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, butyrosulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent can also be an ether solvent. The ether solvent can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ether.

[0130] Among them, the gel electrolyte includes a polymer as a skeleton network of the electrolyte, and an ionic liquid-lithium salt.

[0131] In some embodiments, the electrode assembly is a wound structure. The positive electrode sheet and the negative electrode sheet are wound into a wound structure.

[0132] In some embodiments, the electrode assembly is a stacked structure.

[0133] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be provided, respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets can be alternately stacked.

[0134] As an example, the positive electrode sheet can be provided in a plurality of pieces, and the negative electrode sheet can be folded to form a plurality of folded sections stacked one on another, with one positive electrode sheet interposed between adjacent folded sections.

[0135] As an example, the positive electrode sheet and the negative electrode sheet can each be folded to form a plurality of folded sections stacked one on another.

[0136] As an example, a plurality of separators can be provided, each provided between any adjacent positive electrode sheet or negative electrode sheet.

[0137] As an example, a separator can be provided continuously, and can be provided between any adjacent positive electrode sheet or negative electrode sheet by folding or winding.

[0138] In some embodiments, the electrode assembly can have a cylindrical shape, a flat shape, or a polygonal shape.

[0139] In some embodiments, the electrode assembly can be provided with a tab, which can lead current out of the electrode assembly. The tab can include a positive tab and a negative tab.

[0140] In some embodiments, the battery cell can include a case. The case can be used to enclose components such as the electrode assembly and the electrolyte. The case can be a steel case, an aluminum case, a plastic case (e.g., a polypropylene case), a composite metal case (e.g., a copper-aluminum composite case), or an aluminum-plastic film.

[0141] In some embodiments, the case can be a sealed structure or a non-sealed structure. As an example, when the case is a sealed structure, the case can protect the electrode assembly and can prevent, to some extent, leakage of the electrolyte. When the case is a non-sealed structure, the case can protect the electrode assembly, and a sealing bag can be further included between the case and the electrode assembly. The sealing bag can be used to enclose components such as the electrode assembly and the electrolyte. Specifically, the sealing bag can be a bag-shaped insulating member or an aluminum-plastic film.

[0142] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell having another shape. The prismatic battery cell can include a square battery cell, a blade battery cell, or a polygonal battery cell such as a hexagonal battery cell.

[0143] A battery apparatus according to embodiments of the present application can include one or more battery cell assemblies to provide voltage and capacity. The battery cell assembly can include a plurality of battery cells connected in series, in parallel, or in a mixed connection through a busbar.

[0144] In some embodiments, a battery cell assembly is generally formed by arranging a plurality of battery cells; as an example, the battery cell assembly can be a battery module, which is formed by arranging and fixing a plurality of battery cells into a separate module.

[0145] As an example, the battery module can be formed by bundling a plurality of battery cells with a cable tie.

[0146] In some embodiments, the battery device can be a battery pack, which can include a box and one or more battery cell assemblies, the battery cell assemblies being accommodated in the box.

[0147] As an example, the battery cell assembly can be a battery module, which can be accommodated in the box by fixing the battery module in the box.

[0148] As an example, the battery cell assembly can also be accommodated in the box by directly fixing a plurality of battery cells in the box.

[0149] As an example, the box can include a first box body and a second box body. The first box body and the second box body are buckled so that a closed space is formed inside the box to accommodate the battery cell assembly. Here, closed means covered or closed, which can be sealed or unsealed. The first box body can be a top cover or a bottom plate.

[0150] As an example, the box can include a top cover, a frame and a bottom plate. The top cover and the bottom plate are respectively connected with the frame, so that a closed space is formed inside the box to accommodate the battery cell assembly.

[0151] As an example, the box can be part of the chassis structure of a vehicle. For example, the top cover of the box can be at least part of the floor of the vehicle, or the frame of the box can be at least part of the cross beam and the longitudinal beam of the vehicle.

[0152] In some embodiments, the battery device refers to an energy storage device, which includes a box, at least one side of which is provided with a door. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0153] At present, from the development of market situation, the application of batteries is more and more extensive. Batteries are not only applied to energy storage power supply systems such as hydroelectric, thermal, wind and solar power stations, but also widely used in electric bicycles, electric motorcycles, electric vehicles and other electric vehicles, military equipment, aerospace and other fields. With the continuous expansion of the application field of batteries, the demand for its market is also increasing.

[0154] Batteries are widely used in new energy fields, such as electric vehicles, new energy vehicles, etc. New energy vehicles and electric vehicles have become a new trend in the development of the automobile industry. The development of battery technology needs to consider various design factors, such as energy density, discharge capacity, charge-discharge rate, and other performance parameters. In addition, the reliability of the battery also needs to be considered. However, the reliability of the current battery is poor.

[0155] To improve the reliability of the battery cell, the prior art provides a pressure relief mechanism on the end cover of the battery cell. The pressure relief mechanism has a weak part. When the internal pressure of the battery cell reaches the burst pressure, the weak part is cracked to release the internal pressure of the battery cell, thereby reducing the risk of explosion and fire of the battery cell.

[0156] The pressure relief mechanism in the prior art is generally made of aluminum. The weak part is generally a non-closed structure with two open ends, such as a C-shaped or U-shaped weak part. The open end of the C-shaped or U-shaped weak part faces the width direction of the end cover, and the weak part defines a pressure relief area. For the pressure relief mechanism made of aluminum, the pressure relief area is prone to crack along the weak part and flip open around the open end of the C-shaped or U-shaped weak part when the battery cell is relieved. However, the pressure relief mechanism made of aluminum has low strength, and the weak part is prone to crack under the action of internal pressure changes or external impact of the battery cell, i.e., the weak part cracks before the internal pressure of the battery cell reaches the desired burst pressure, resulting in premature scrapping of the battery cell and poor reliability of the battery cell.

[0157] If only a material with higher strength is used to manufacture the pressure relief mechanism, the open end of the C-shaped or U-shaped weak part has high resistance when the battery cell is relieved, making it difficult for the pressure relief area to flip open around the open end of the C-shaped or U-shaped weak part after cracking along the weak part, or the angle of the flipped open pressure relief area is small, and the open opening is small, making it difficult to achieve rapid pressure relief. In addition, after the pressure relief area flips open, the pressure relief area still hangs on the pressure relief mechanism. Since the open end of the C-shaped or U-shaped weak part faces the width direction of the end cover, the high-temperature gas ejected from the battery cell is easily bounced back to the adjacent battery cell by the pressure relief area, thereby easily causing thermal runaway of the adjacent battery cell, resulting in poor reliability of the battery cell.

[0158] Therefore, the embodiments of the present application provide a battery cell. The battery cell includes a shell and a pressure relief mechanism. The shell has a first wall part, and the pressure relief mechanism is arranged on the first wall part. The base material of the pressure relief mechanism is iron. The pressure relief mechanism includes a weak part configured to be at least partially destroyed to release pressure when the internal pressure of the shell reaches a threshold value. The thinnest region of the weak part is located on both sides of the weak part in the width direction of the first wall part.

[0159] The base material of the pressure relief mechanism is iron, which can effectively improve the structural strength of the pressure relief mechanism, reduce the risk of the pressure relief mechanism opening the valve to relieve pressure in advance, and improve the service life and reliability of the battery monomer. The thinnest area of the weak part is located on both sides of the weak part in the width direction of the first wall part. When the pressure inside the shell reaches the threshold value, the thinnest area of the weak part will crack first, that is, the two sides of the weak part in the width direction of the first wall part will crack first. In this way, even if the pressure relief area defined by the weak part is not completely opened, the high-temperature gas sprayed out is not easy to diffuse along the width direction of the first wall part, and when diffusing along other directions, the high-temperature gas is not easy to diffuse to the other battery monomer adjacent to it, and is not easy to cause the other battery monomer to thermal runaway, which is beneficial to improve the reliability of the battery device.

[0160] The technical solutions described in the embodiments of the present application are applicable to various electric devices using battery monomers and battery devices, for example, mobile phones, portable devices, notebook computers, electric vehicles, electric toys, electric tools, vehicles, ships and spacecraft, etc. For example, the spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc.

[0161] The following embodiments are described for convenience with the electric device being a vehicle as an example.

[0162] Please refer to FIG. 1, which is a structural schematic diagram of a vehicle 1000 provided by some embodiments of the present application. The vehicle 1000 is internally provided with a battery device 100, which can be arranged at the bottom, head or tail of the vehicle 1000. The battery device 100 can be used for power supply of the vehicle 1000, for example, the battery device 100 can be used as an operating power source of the vehicle 1000.

[0163] The vehicle 1000 can also include a controller 200 and a motor 300, and the controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, for the working power demand of the vehicle 1000 during starting, navigation and driving.

[0164] In some embodiments of the present application, the battery device 100 can not only be used as an operating power source of the vehicle 1000, but also be used as a driving power source of the vehicle 1000, instead of or partially instead of fuel or natural gas to provide driving power for the vehicle 1000.

[0165] Please refer to FIG. 2, which is an exploded view of the battery device 100 provided by some embodiments of the present application. The battery device 100 can include a box 10 and a battery monomer 20, and the box 10 is used to accommodate the battery monomer 20.

[0166] The box 10 has an enclosed space inside for accommodating the battery cell 20. The box 10 can have various structures. In some embodiments, the box 10 can include a first box body 11 and a second box body 12, which are coupled to each other. The first box body 11 and the second box body 12 can have various shapes, such as a cuboid, a cylinder, etc. The first box body 11 can be a hollow structure with one side open, and the second box body 12 can also be a hollow structure with one side open. The open side of the second box body 12 is coupled to the open side of the first box body 11, and thus the box 10 with the enclosed space is formed. Alternatively, the first box body 11 can be a hollow structure with one side open, and the second box body 12 can be a plate-shaped structure. The second box body 12 is coupled to the open side of the first box body 11, and thus the box 10 with the enclosed space is formed.

[0167] In the battery device 100, the battery cell 20 can be one or multiple. If the battery cell 20 is multiple, the multiple battery cells 20 can be connected in series, in parallel, or in a mixed manner. The mixed manner means that the multiple battery cells 20 are connected in series and in parallel. The multiple battery cells 20 can be connected in series, in parallel, or in a mixed manner to form a battery module, and the multiple battery modules are connected in series, in parallel, or in a mixed manner to form a whole, which is accommodated in the box 10. Alternatively, the multiple battery cells 20 can be directly connected in series, in parallel, or in a mixed manner, and the whole formed by the multiple battery cells 20 is accommodated in the box 10.

[0168] In some embodiments, the battery device 100 can further include a current collecting component. The multiple battery cells 20 can be electrically connected through the current collecting component to achieve the connection in series, in parallel, or in a mixed manner. The current collecting component can be a metal conductor, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc.

[0169] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, and FIG. 7. FIG. 3 is a structural schematic diagram of the battery cell 20 provided in some embodiments of the present application. FIG. 4 is an exploded view of the battery cell 20 provided in some embodiments of the present application. FIG. 5 is a top view of the first wall portion 213 provided in some embodiments of the present application. FIG. 6 is a sectional view of the position A-A in FIG. 5. FIG. 7 is a structural schematic diagram of the pressure relief mechanism 24 provided in some embodiments of the present application. The embodiments of the present application provide a battery cell 20, which includes an outer shell 21 and a pressure relief mechanism 24. The outer shell 21 has a first wall portion 213, and the pressure relief mechanism 24 is arranged on the first wall portion 213. The base material of the pressure relief mechanism 24 is iron. The pressure relief mechanism 24 includes a weak portion 2421a, which is configured to be at least partially destroyed to release pressure when the pressure inside the outer shell 21 reaches a threshold value. The thinnest region of the weak portion 2421a is located at least on both sides of the weak portion 2421a in the width direction of the first wall portion 213.

[0170] The battery cell 20 refers to the smallest unit that constitutes the battery device 100.

[0171] The housing 21 includes a casing 211 and an end cap 212. The casing 211 has an open-ended receiving space for receiving the electrode assembly 23. The end cap 212 is coupled to the casing 211 and closes the opening.

[0172] The end cap 212 refers to a component that covers the opening of the casing 211 to isolate the internal environment of the battery cell 20 from the external environment. Without limitation, the shape of the end cap 212 can be adapted to the shape of the casing 211 to fit the casing 211. Alternatively, the end cap 212 can be made of a material having a certain degree of hardness and strength, such as an aluminum alloy, so that the end cap 212 is less likely to deform when subjected to a pressing impact, allowing the battery cell 20 to have a higher structural strength and improved reliability. The material of the end cap 212 can include, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc. The end cap 212 is further provided with an electrode terminal 25 for electrically connecting to the tab 232 of the electrode assembly 23 to input or output the electric energy of the battery cell 20. The electrode terminal 25 can be directly connected to the tab 232, such as being directly welded to the tab 232. The electrode terminal 25 can also be indirectly connected to the tab 232, such as being indirectly connected to the tab 232 through a current collecting member. The battery cell 20 further includes an insulating member 27 disposed on the inner side of the end cap 212. The insulating member 27 can be used to isolate the electrically connecting components within the casing 211 from the end cap 212 to reduce the risk of short circuit. The insulating member 27 can be, for example, plastic, rubber, etc.

[0173] The casing 211 is a component for fitting the end cap 212 to form the internal environment of the battery cell 20, which can be used to accommodate the electrode assembly 23, the electrolyte, and other components. The casing 211 and the end cap 212 can be independent components, and an opening can be provided on the casing 211. The end cap 212 is made to cover the opening to form the internal environment of the battery cell 20. Without limitation, the end cap 212 and the casing 211 can also be integrated. Specifically, the end cap 212 and the casing 211 can first form a common joint surface before other components enter the casing, and then the end cap 212 is made to cover the casing 211 when it is necessary to seal the internal environment of the casing 211. The casing 211 can have various shapes and sizes, such as a cuboid, a cylinder, a hexagonal prism, etc. Specifically, the shape of the casing 211 can be determined according to the specific shape and size of the electrode assembly 23. The material of the casing 211 can include, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0174] The electrode assembly 23 is a component in which electrochemical reactions occur in the battery cell 20. One or more electrode assemblies 23 can be contained within the case 211. The electrode assembly 23 is mainly formed by winding or layering a positive electrode sheet and a negative electrode sheet, and an insulating film is generally provided between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and the negative electrode sheet have portions with active materials that constitute a main body 231 of the electrode assembly 23, and portions without active materials that each constitute a tab 232. The positive and negative tabs can be collectively located at one end of the main body 231 or at opposite ends of the main body 231. During charging and discharging of the battery cell 20, the positive and negative active materials react with an electrolyte.

[0175] The first wall portion 213 can be an end cap 212 of the case 21 or a wall of the case 211 of the case 21. Exemplarily, in FIGS. 3 and 4, the first wall portion 213 is the end cap 212. In other embodiments, the first wall portion 213 is a bottom wall of the case 211 that is disposed opposite the end cap 212. In yet other embodiments, the first wall portion 213 can also be a side wall of the case 211 that is adjacent to and connected to the end cap 212.

[0176] The pressure relief mechanism 24 is a component for opening when the internal pressure or temperature of the battery cell 20 reaches a burst pressure to release the internal pressure of the battery cell 20. The pressure relief mechanism 24 is a component that is mounted on the first wall portion 213, and the pressure relief mechanism 24 is provided separately from the first wall portion 213 and connected thereto. During manufacturing, a pressure relief hole 2131 is formed in the first wall portion 213, and the pressure relief mechanism 24 and the first wall portion 213 are provided separately and finally connected together so that the pressure relief mechanism 24 covers the pressure relief hole 2131. For example, the pressure relief mechanism 24 can be welded to the first wall portion 213. The pressure relief mechanism 24 can be a burst disc that is mounted on the first wall portion 213. The wall portion of the case 21 that is the first wall portion 213 can be determined by the position at which the pressure relief mechanism 24 is provided. For example, when the pressure relief mechanism 24 is provided in the end cap 212, the end cap 212 is the first wall portion 213. When the pressure relief mechanism 24 is provided in the bottom wall of the case 211, the bottom wall is the first wall portion 213. When the pressure relief mechanism 24 is provided in the side wall of the case 211, the side wall is the first wall portion 213.

[0177] “the base material of the pressure relief mechanism 24 is iron” means that the material with the largest mass percentage in the material of the pressure relief mechanism 24 is iron. For example, the material of the pressure relief mechanism 24 can be carbon steel or stainless steel. The carbon steel can be low carbon steel, medium carbon steel, or high carbon steel.

[0178] The weak portion 2421a functions as a pressure relief portion for enabling the pressure relief mechanism 24 to be broken along at least a portion of the weak portion 2421a to release the pressure inside the battery cell 20 when the internal pressure or temperature of the battery cell 20 reaches a threshold value. In some embodiments, the strength of the pressure relief mechanism 24 at the position of the weak portion 2421a can be lower than the strength of the pressure relief mechanism 24 at other positions, so that the weak portion 2421a can be broken by the internal pressure when the internal pressure or temperature of the battery cell 20 reaches a predetermined value to release the pressure inside the battery cell 20. In other embodiments, the melting point of the pressure relief mechanism 24 at the position of the weak portion 2421a can be lower than the melting point of the pressure relief mechanism 24 at other positions. In this way, the weak portion 2421a can be broken by the high temperature when the internal pressure or temperature of the battery cell 20 reaches a predetermined value to release the pressure inside the battery cell 20.

[0179] The weak portion 2421a can have a ring shape, for example, the weak portion 2421a can have a circular ring shape or an elliptical ring shape. The weak portion 2421a can also have a non-ring shape, for example, the weak portion 2421a can have a C shape or a U shape. The area enclosed by the weak portion 2421a is a pressure relief area 2422, where the area enclosed by the weak portion 2421a is the area in which the pressure relief mechanism 24 forms an opening after the weak portion 2421a is broken by the gas inside the housing 21. When the weak portion 2421a has a ring shape, the area enclosed by the weak portion 2421a is the area inside the ring shape. When the weak portion 2421a has a non-ring shape, the area enclosed by the weak portion 2421a is the area inside the ring shape formed by the weak portion 2421a itself and the line connecting the two ends of the weak portion 2421a. When the battery cell 20 is relieved, the pressure relief area 2422 is broken along the weak portion 2421a, thereby opening a larger opening to relieve pressure.

[0180] Please refer to FIG. 4, FIG. 5 and FIG. 6, the width direction of the first wall portion 213 is the Y direction shown in the figures. The length direction of the first wall portion 213 is the Z direction shown in the figures.

[0181] The thinnest region of the weakened portion 2421a is at least on both sides of the weakened portion 2421a in the width direction of the first wall portion 213. The thinnest region of the weakened portion 2421a can also be on one side of the weakened portion 2421a in the length direction of the first wall portion 213 and connected to the thinnest regions on both sides of the weakened portion 2421a in the width direction of the first wall portion 213.

[0182] The base material of the pressure relief mechanism 24 is iron, which can effectively improve the structural strength of the pressure relief mechanism 24, reduce the risk of the pressure relief mechanism 24 opening prematurely, and improve the service life and reliability of the battery monomer 20. The thinnest region of the weakened portion 2421a is at least on both sides of the weakened portion 2421a in the width direction of the first wall portion 213. When the pressure inside the shell 21 reaches the threshold value, the thinnest region of the weakened portion 2421a will crack first, that is, the two sides of the weakened portion 2421a in the width direction of the first wall portion 213 will crack first. Even if the weakened portion 2421a defines a pressure relief area 2422 that is not fully open, the high-temperature gas sprayed out is not easy to spread along the width direction of the first wall portion 213, but along other directions, because the path to the adjacent another battery monomer 20 is far away, the high-temperature gas is not easy to spread to the adjacent another battery monomer 20, and is not easy to cause another battery monomer 20 to thermal runaway, which is beneficial to improve the reliability of the battery device 100.

[0183] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6 and FIG. 7. In some embodiments, the weakened portion 2421a is in the shape of a closed ring. The difference between the minimum thicknesses of the cross sections of the weakened portion 2421a at any two positions in the extension direction of the weakened portion 2421a is less than 0.01 mm, and the cross sections are perpendicular to the extension direction.

[0184] The weakened portion 2421a is a ring structure extending along a ring trajectory. The extension direction of the weakened portion 2421a is the extension direction of the ring trajectory.

[0185] In the extension direction of the weakened portion 2421a, the difference between the minimum thicknesses of the cross sections of the weakened portion 2421a at any two positions in the extension direction of the weakened portion 2421a is less than 0.01 mm, that is, the minimum thicknesses of the weakened portion 2421a at any two positions in the extension direction of the weakened portion 2421a are substantially the same.

[0186] By making the difference between the minimum thicknesses of the cross sections of the weakened portion 2421a at any two positions in the extension direction thereof less than 0.01 mm, i.e., the minimum thicknesses of the weakened portion 2421a at any two positions in the extension direction thereof are substantially the same, when the pressure inside the shell 21 reaches the threshold value, the pressure relief mechanism 24 can crack along the entire circumference of the weakened portion 2421a, so that the pressure relief area 2422 defined by the weakened portion 2421a can be separated from the pressure relief mechanism 24, the pressure relief area 2422 is less likely to hang on the pressure relief mechanism 24 and block the gas eruption, the risk of high-temperature gas being ejected to the adjacent battery cell 20 is reduced, and the reliability of the battery cell 20 is improved.

[0187] Optionally, the minimum thicknesses of the cross sections of the weakened portion 2421a at any two positions in the extension direction thereof are equal.

[0188] By making the minimum thicknesses of the cross sections of the weakened portion 2421a at any two positions in the extension direction thereof equal, when the pressure inside the shell 21 reaches the threshold value, the pressure relief mechanism 24 can crack along the entire circumference of the weakened portion 2421a, so that the pressure relief area 2422 defined by the weakened portion 2421a can be separated from the pressure relief mechanism 24, the pressure relief area 2422 is less likely to hang on the pressure relief mechanism 24 and block the gas eruption, the risk of high-temperature gas being ejected to the adjacent battery cell 20 is reduced, and the reliability of the battery cell 20 is improved.

[0189] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6 and FIG. 7. In some embodiments, the minimum thickness of the weakened portion 2421a is H1, which satisfies: 0.01 mm≤H1≤0.2 mm.

[0190] H1 represents the minimum thickness of the weakened portion 2421a. When measuring, the thicknesses of the weakened portion 2421a at different positions can be measured multiple times and the average value is taken as H1.

[0191] The minimum thickness of the weakened portion 2421a can be: H1=0.01 mm, 0.02 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, etc.

[0192] When H1 is greater than or equal to 0.01 mm, the thickness of the weak portion 2421a is relatively large, and the weak portion 2421a is not prone to being broken in advance due to changes in the internal pressure of the battery monomer 20 or external impact, which is conducive to reducing the risk of the weak portion 2421a being damaged in advance and improving the service life and reliability of the battery monomer 20. When H1 is less than or equal to 0.2 mm, the thickness of the weak portion 2421a is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery monomer 20 is in thermal runaway, which is conducive to improving the timeliness of pressure relief of the pressure relief mechanism 24. Therefore, when 0.01 mm≤H1≤0.2 mm, the service life and the timeliness of pressure relief of the battery monomer 20 can be considered.

[0193] Optionally, 0.01 mm≤H1≤0.15 mm.

[0194] The minimum thickness of the weak portion 2421a can be: H1=0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, etc.

[0195] When H1 is greater than or equal to 0.01 mm, the thickness of the weak portion 2421a is relatively large, and the weak portion 2421a is not prone to being broken in advance due to changes in the internal pressure of the battery monomer 20 or external impact, which is conducive to reducing the risk of the weak portion 2421a being damaged in advance and improving the service life and reliability of the battery monomer 20. When H1 is less than or equal to 0.15 mm, the thickness of the weak portion 2421a is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery monomer 20 is in thermal runaway, which is conducive to improving the timeliness of pressure relief of the pressure relief mechanism 24. Therefore, when 0.01 mm≤H1≤0.15 mm, the service life and the timeliness of pressure relief of the battery monomer 20 can be considered.

[0196] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8 and FIG. 9, FIG. 8 is a top view of the pressure relief mechanism 24 provided by some embodiments of the application. FIG. 9 is a sectional view of the position B-B in FIG. 8. In some embodiments, the weak portion 2421a is in a closed ring shape, and the weak portion 2421a includes a first weak segment 24212 and a second weak segment 24213 connected in a head-to-tail manner. The thickness of the second weak segment 24213 is greater than that of the first weak segment 24212, and the second weak segment 24213 is located on one side of the weak portion 2421a in the length direction of the first wall portion 213.

[0197] The first weak section 24212 functions to relieve pressure, so as to enable the pressure relief mechanism 24 to split along at least a portion of the first weak section 24212 when the internal pressure or temperature of the battery monomer 20 reaches a threshold, to release the pressure inside the battery monomer 20. In other words, the first weak section 24212 is the thinnest area of the thinnest part 2421a.

[0198] The second weak section 24213 functions to guide at least a portion of the pressure relief area 2422 to flip open. The second weak section 24213 has a higher strength than the first weak section 24212. When the battery monomer 20 is relieved of pressure, the first weak section 24212 splits first, to allow the gas inside the battery monomer 20 to flow out. Then, the pressure relief area 2422 can flip outward around the connecting line between the two ends of the second weak section 24213 under the action of the gas, to open a larger opening, to achieve rapid pressure relief.

[0199] The second weak section 24213 is located on one side of the thinnest part 2421a in the length direction of the first wall part 213. Please refer to FIG. 8, the left-right direction is the length direction of the first wall part 213. At this time, the second weak section 24213 is located on the left side of the thinnest part 2421a. In this way, when the battery monomer 20 is relieved of pressure, even if the pressure relief area 2422 does not completely open, the high-temperature gas sprayed out will diffuse towards the length direction of the first wall part 213 under the action of the pressure relief area 2422, that is, the high-temperature gas sprayed out is less likely to diffuse to another battery monomer 20 adjacent thereto.

[0200] By providing the second weak section 24213, the strength of the pressure relief mechanism 24 at the position of the second weak section 24213 is weakened, so that the pressure relief area 2422 is more likely to flip open under the action of the internal pressure of the battery monomer 20, not only can improve the probability of the pressure relief area 2422 opening, but also can improve the opening speed of the pressure relief area 2422, to achieve rapid pressure relief, reduce the risk of explosion and fire of the battery monomer 20, and is conducive to improving the reliability of the battery monomer 20. By locating the second weak section 24213 on one side of the thinnest part 2421a in the length direction of the first wall part 213, when the battery monomer 20 is relieved of pressure, even if the pressure relief area 2422 does not completely open, the high-temperature gas sprayed out will diffuse towards the length direction of the first wall part 213 under the action of the pressure relief area 2422, and when diffusing along the length direction of the first wall part 213, the path to another battery monomer 20 adjacent thereto is farther, that is, the high-temperature gas sprayed out is less likely to diffuse to another battery monomer 20 adjacent thereto, and is less likely to cause another battery monomer 20 to thermal runaway, which is conducive to improving the reliability of the battery device 100.

[0201] Please refer to FIG. 10, which is a top view of the pressure relief mechanism 24 provided by some embodiments of the present application. In some embodiments, the second weak section 24213 extends along a straight line trajectory.

[0202] The second weak section 24213 extends along a straight line trajectory, i.e., the second weak section 24213 is straight.

[0203] The second weak section 24213 extends along a straight line trajectory, which is convenient in manufacturing and can be quickly opened when the battery cell 20 is pressure released.

[0204] Referring to FIG. 9 again, in some embodiments, the second weak section 24213 extends along an arc trajectory.

[0205] The second weak section 24213 extends along an arc trajectory, i.e., the second weak section 24213 is arc-shaped. For example, the second weak section 24213 can be circular arc-shaped.

[0206] The second weak section 24213 extends along an arc trajectory, which is beneficial to reduce stress concentration.

[0207] Referring to FIGS. 3, 4, 5, 6, 7, 8 and 9, in some embodiments, the thickness of the first weak section 24212 is H1, and the thickness of the second weak section 24213 is H2, which satisfies: H2-H1≥0.01 mm.

[0208] The thickness of the first weak section 24212 can be the minimum thickness of the weak section 2421a.

[0209] H2 represents the thickness of the second weak section 24213, which can be measured by measuring the thickness of the second weak section 24213 at different positions multiple times and taking the average value as H2.

[0210] H2-H1 represents the difference between the thickness of the second weak section 24213 and the thickness of the first weak section 24212.

[0211] The difference between the thickness of the second weak section 24213 and the thickness of the first weak section 24212 can be: H2-H1=0.01 mm, 0.02 mm, 0.03 mm, 0.05 mm, 0.08 mm, 0.1 mm, etc.

[0212] When H2-H1≥0.01 mm, the thickness of the second weak section 24213 is greatly different from the thickness of the first weak section 24212, and the second weak section 24213 is not easy to crack when the battery cell 20 is pressure released, so that the second weak section 2421a can better guide the turning of the pressure release area 2422.

[0213] Optionally, H2-H1≥0.05 mm.

[0214] The difference between the thickness of the second weak section 24213 and the thickness of the first weak section 24212 can be: H2-H1=0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, etc.

[0215] When H2-H1≥0.05mm, the thickness of the second weak section 24213 is more different from the thickness of the first weak section 24212, and the second weak section 24213 is less likely to crack when the battery cell 20 is pressure released, so that the second weak section 2421a can better guide the turning of the pressure release area 2422.

[0216] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8 and FIG. 9, in some embodiments, 0.05mm≤H2≤0.4mm.

[0217] The thickness of the second weak section 24213 can be: H2=0.05mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.28mm, 0.3mm, 0.32mm, 0.35mm, 0.38mm, 0.4mm.

[0218] When H2≥0.05mm, the thickness of the second weak section 24213 is large, which can reduce the risk of the second weak section 24213 cracking due to changes in internal pressure of the battery cell 20 or external impact, and is beneficial to improve the reliability of the battery cell 20. When H2≤0.4mm, the second thickness is not too large, thereby facilitating the reduction of the resistance of the pressure release area 2422 turning, facilitating the rapid turning of the pressure release area 2422 to open, and being beneficial to improve the timeliness of the pressure release of the battery cell 20. Therefore, when 0.05mm≤H2≤0.4mm, the thickness of the second weak section 24213 is moderate, the second weak section 24213 is neither easy to crack due to changes in internal pressure of the battery cell 20, nor facilitates the rapid turning of the pressure release area 2422 to open, and is beneficial to improve the timeliness of the pressure release of the battery cell 20.

[0219] Please refer to FIG. 7, FIG. 8 and FIG. 9, in some embodiments, the first weak section 24212 includes a first section 24212a, a second section 24212b and a third section 24212c, and the first section 24212a, the second section 24212b, the third section 24212c and the second weak section 24213 are connected end to end. The first section 24212a and the third section 24212c are located on both sides of the weak section 2421a in the width direction of the first wall portion 213.

[0220] The first weakened section 24212 includes a first section 24212a, a second section 24212b and a third section 24212c, the first section 24212a and the third section 24212c are oppositely arranged along the width direction of the first wall portion 213, one end of the second section 24212b is connected to one end of the first section 24212a, and the other end of the second section 24212b is connected to one end of the third section 24212c. The second weakened section 24213 connects the other end of the first section 24212a and the other end of the third section 24212c. The first section 24212a, the second section 24212b, the third section 24212c and the second weakened section 24213 together define a pressure relief area 2422.

[0221] The first section 24212a and the third section 24212c are located on both sides of the weakened portion 2421a in the width direction of the first wall portion 213, and the line connecting the two ends of the second weakened section 24213 is substantially parallel to the width direction of the first wall portion 213. When the battery cell 20 is relieved of pressure, even if the pressure relief area 2422 is not completely opened, the high-temperature gas sprayed out will move substantially along the length direction of the first wall portion 213 after being bounced back by the pressure relief area 2422. The distance between the battery cell 20 and the adjacent battery cell 20 along the length direction of the first wall portion 213 is large, so the high-temperature gas sprayed out is not easy to be bounced to the other adjacent battery cell 20, and the other adjacent battery cell 20 is not easy to cause thermal runaway. This is beneficial to improve the reliability of the battery cell 20.

[0222] Please refer to FIG. 7, FIG. 8 and FIG. 9. In some embodiments, the first section 24212a and / or the third section 24212c extends along a straight line trajectory.

[0223] The first section 24212a and / or the third section 24212c extends along a straight line trajectory, that is, the first section 24212a and / or the third section 24212c is linear.

[0224] By making the first section 24212a and / or the third section 24212c extend along a straight line trajectory, it is easier to crack along the first section 24212a and the third section 24212c when the battery cell 20 is relieved of pressure, which can improve the opening speed of the pressure relief area 2422 and achieve rapid pressure relief.

[0225] Please refer to FIG. 12, which is a top view of the pressure relief mechanism 24 provided in some embodiments of the present application. In some embodiments, the weakened portion is in the shape of an opening, and the opening end of the weakened portion is located on one side of the weakened portion in the length direction of the first wall portion.

[0226] The weak portion 2421a can be in a shape of C, U, or the like with an opening at one end. The opening end of the weak portion 2421a is located at one side of the weak portion 2421a in the length direction of the first wall portion 213. Referring to FIG. 12, the left-right direction is the length direction of the first wall portion 213. At this time, the opening end of the weak portion 2421a is located at the left side of the weak portion 2421a. In this way, when the battery cell 20 is depressurized, even if the pressure relief area 2422 is not completely opened, the high-temperature gas sprayed out can diffuse toward the length direction of the first wall portion 213 under the action of the pressure relief area 2422. When diffusing along the length direction of the first wall portion 213, the path to the other battery cell 20 adjacent thereto is farther, that is, the high-temperature gas sprayed out is less likely to diffuse to the other battery cell 20 adjacent thereto, and the other battery cell 20 is less likely to be triggered to thermal runaway. This is conducive to improving the reliability of the battery device 100.

[0227] By locating the opening end of the weak portion 2421a at one side of the weak portion 2421a in the length direction of the first wall portion 213, when the battery cell 20 is depressurized, the pressure relief area 2422 is opened by turning around the opening end. Even if the pressure relief area 2422 is not completely opened, the high-temperature gas sprayed out can diffuse toward the length direction of the first wall portion 213 under the action of the pressure relief area 2422. When diffusing along the length direction of the first wall portion 213, the path to the other battery cell 20 adjacent thereto is farther, that is, the high-temperature gas sprayed out is less likely to diffuse to the other battery cell 20 adjacent thereto, and the other battery cell 20 is less likely to be triggered to thermal runaway. This is conducive to improving the reliability of the battery device 100.

[0228] In some embodiments, the material of the pressure relief mechanism 24 is 304 stainless steel, 305 stainless steel, or 316 stainless steel.

[0229] 304 stainless steel, 305 stainless steel, and 316 stainless steel have the advantages of corrosion resistance, high temperature resistance, and good processing performance. The pressure relief mechanism 24 made of 304 stainless steel, 305 stainless steel, or 316 stainless steel has high strength, which can reduce the risk of deformation of the pressure relief mechanism 24 under stress, is conducive to reducing the risk of early valve opening and pressure relief of the pressure relief mechanism 24, is conducive to improving the service life and reliability of the battery cell 20, and is conducive to improving the consistency of the ignition pressure of the plurality of battery cells 20.

[0230] In some embodiments, the battery cell 20 includes an electrode assembly 23 accommodated in the housing 21. The electrode assembly 23 includes a positive electrode sheet including a positive electrode active material capable of reversible deintercalation-intercalation of metal ions, and the positive electrode active material includes a nickel element-containing compound.

[0231] In the case that the positive active material of the positive electrode plate includes a nickel-containing compound, the energy density and long cycle life of the battery monomer 20 can be effectively increased, and the gas generated during the use of the battery monomer 20 is also increased, especially in the case of thermal runaway of the battery monomer 20, the temperature inside the battery monomer 20 increases rapidly and a large amount of gas is generated, which is more likely to cause thermal runaway of adjacent battery monomers 20. Therefore, the battery monomer 20 with the positive active material including the nickel-containing compound has better effect in the present application.

[0232] In some embodiments, the nickel-containing compound includes a layered lithium-containing transition metal oxide, and the molar amount of nickel elements in the layered lithium-containing transition metal oxide accounts for more than 50% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide.

[0233] By making the molar amount of nickel elements in the layered lithium-containing transition metal oxide account for more than 50% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide, the energy density and long cycle life of the battery monomer 20 can be effectively improved.

[0234] Optionally, the molar amount of nickel elements in the layered lithium-containing transition metal oxide accounts for more than 80% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide.

[0235] By making the molar amount of nickel elements in the layered lithium-containing transition metal oxide account for more than 80% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide, the energy density and long cycle life of the battery monomer 20 can be more effectively improved.

[0236] In some embodiments, the layered lithium-containing transition metal oxide includes Li a Ni b Co c M d O e A f , wherein 0

[0237] For example, the layered lithium-containing transition metal oxide can include but is not limited to LiNi 0.5 Co 0.2 Mn 0.3 O2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25O2 (abbreviated as NCM 211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (abbreviated as NCM 622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM 811), LiNi 0.9 Co 0.06 Mn 0.04 O2, LiNi 0.96 Co 0.02 Mn 0.02 O2, LiNi 0.85 Co 0.15 Al 0.05 O2.

[0238] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8 and FIG. 9, in some embodiments, the pressure relief mechanism 24 includes a raised portion 24221 and a connecting portion 241, the raised portion 24221 is located in the area surrounded by the weakened portion 2421a. The connecting portion 241 is located outside the weakened portion 2421a and is provided on the first wall portion 213. The raised portion 24221 is a raised structure raised in a direction away from the inside of the shell 21.

[0239] The weakened portion 2421a divides the pressure relief mechanism 24 into two parts, one part is located inside the weakened portion 2421a, and the other part is located outside the weakened portion 2421a.

[0240] The raised portion 24221 is located inside the weakened portion 2421a, and the raised portion 24221 is a raised structure raised in a direction away from the electrode assembly 23. The raised structure is a structure in which the inner surface and the outer surface are both arched in a direction away from the electrode assembly 23.

[0241] The connecting portion 241 is located outside the weakened portion 2421a, and the connecting portion 241 is the part of the pressure relief mechanism 24 for connecting the first wall portion 213, for example, the connecting portion 241 can be welded to the first wall portion 213.

[0242] The existing pressure relief mechanism 24 is gradually arched away from the electrode assembly 23 under the action of the internal pressure of the battery monomer 20 when pressure relief, and then opens under the action of the internal pressure of the battery monomer 20. In the embodiment of the application, the bulge part 24221 of the pressure relief mechanism 24 is arched away from the electrode assembly 23, and the bulge part 24221 forms a pre-deformation on the inner side of the weak part 2421a, thereby facilitating the cracking of the weak part 2421a for pressure relief. In this way, under the same burst pressure, the thickness of the weak part 2421a can be greater, and the weak part 2421a is not easily cracked in advance due to changes in the internal pressure of the battery monomer 20 or external impact when the battery monomer 20 is normally used, which is beneficial to reduce the risk of the weak part 2421a being damaged in advance and improve the service life of the battery monomer 20. Compared with the aluminum material explosion valve in the prior art, the thickness of the weak part 2421a of the pressure relief mechanism 24 provided in the embodiment of the application is smaller, and a slight change in the thickness of the weak part 2421a will cause a great change in the burst pressure of the battery monomer 20 during manufacturing. By providing the bulge part 24221, the thickness of the weak part 2421a can be increased under the same burst pressure, and the greater the thickness of the weak part 2421a, the easier it is to manufacture, thereby facilitating the consistency of the burst pressure of the plurality of battery monomers 20. Furthermore, when the battery monomer 20 expands, the first wall part 213 is deformed under stress, and the bulge part 24221 can be stretched under the action of external force, thereby reducing the pulling of the weak part 2421a by external force and reducing the risk of the weak part 2421a being damaged in advance, which is beneficial to improve the service life of the battery monomer 20.

[0243] In some embodiments, the boundary of the bulge part 24221 at least partially abuts the boundary of the weak part 2421a.

[0244] The "boundary of the bulge part 24221 at least partially abuts the boundary of the weak part 2421a" can also be understood as the boundary of the bulge part 24221 at least partially overlaps the boundary of the weak part 2421a. In other words, at least a part of the weak part 2421a is directly connected to the bulge part 24221.

[0245] Please refer to FIG. 11, which is a cross-sectional view of the pressure relief mechanism 24 provided in some embodiments of the application. In FIG. 11, the boundary of the right end of the bulge part 24221 abuts the boundary of the weak part 2421a, that is, the right end of the bulge part 24221 is directly connected to the weak part 2421a. The boundary of the left end of the bulge part 24221 is gap-set from the boundary of the weak part 2421a, that is, the left end of the bulge part 24221 is gap-set from the weak part 2421a.

[0246] By making the boundary of the protrusion 24221 at least partially contiguous with the boundary of the weakened portion 2421a, when the battery cell 20 is depressurized, the protrusion 24221 can directly pull the weakened portion 2421a through the contiguous portion, so that the portion of the weakened portion 2421a that is contiguous with the boundary of the protrusion 24221 is subjected to a greater shear force, thereby facilitating the opening of the weakened portion 2421a to relieve pressure. In the case of the same burst pressure, the thickness of the weakened portion 2421a can be greater, and the weakened portion 2421a is less likely to be prematurely cracked due to changes in pressure inside the battery cell 20 or external impact during normal use of the battery cell 20, which is conducive to reducing the risk of premature damage to the weakened portion 2421a and improving the service life and reliability of the battery cell 20. In addition, the greater the thickness of the weakened portion 2421a, the easier it is to manufacture, thereby facilitating the consistency of the burst pressure of multiple battery cells 20.

[0247] Please refer to FIGS. 3, 4, 5, 6, 7, 8, and 9. In some embodiments, the boundary of the protrusion 24221 is completely contiguous with the boundary of the weakened portion 2421a.

[0248] The “boundary of the protrusion 24221 is completely contiguous with the boundary of the weakened portion 2421a” can also be understood as the boundary of the protrusion 24221 completely overlapping the boundary of the weakened portion 2421a. It should be noted that the weakened portion 2421a has an inner boundary close to the protrusion 24221 and an outer boundary arranged outside the inner boundary, and here it is only necessary to satisfy that the boundary of the protrusion 24221 completely overlaps the inner boundary of the weakened portion 2421a.

[0249] The “boundary of the protrusion 24221 is completely contiguous with the boundary of the weakened portion 2421a” can also be said to be that each part of the weakened portion 2421a is directly connected to the protrusion 24221.

[0250] Please refer to FIG. 6. In the embodiment shown in FIG. 6, the left and right ends of the protrusion 24221 are directly connected to the weakened portion 2421a.

[0251] By making the boundary of the protrusion 24221 completely contiguous with the boundary of the weak portion 2421a, when the battery cell 20 is depressurized, the protrusion 24221 can directly pull the weak portion 2421a, so that the weak portion 2421a is subjected to greater shear force, thereby facilitating the opening of the weak portion 2421a to depressurize. Under the same burst pressure, the thickness of the weak portion 2421a can be greater, and the weak portion 2421a is less likely to be prematurely cracked due to changes in pressure inside the battery cell 20 or external impact during normal use of the battery cell 20, which is conducive to reducing the risk of premature destruction of the weak portion 2421a and improving the service life and reliability of the battery cell 20. In addition, the greater the thickness of the weak portion 2421a, the easier it is to manufacture, thereby facilitating the consistency of the burst pressure of multiple battery cells 20.

[0252] In some embodiments, the minimum thickness of the weak portion 2421a is H1, satisfying 0.01mm≤H1≤0.2mm.

[0253] When H1≥0.01mm, the thickness of the weak portion 2421a is greater, and the weak portion 2421a is less likely to be prematurely cracked due to changes in pressure inside the battery cell 20 or external impact during normal use of the battery cell 20, which is conducive to reducing the risk of premature destruction of the weak portion 2421a and improving the service life and reliability of the battery cell 20. When H1≤0.2mm, the thickness of the weak portion 2421a is not too large, so that the pressure relief mechanism 24 can timely open to depressurize when the battery cell 20 is out of control, which is conducive to improving the timeliness of the pressure relief mechanism 24 to depressurize. Therefore, when 0.01mm≤H1≤0.2mm, the service life of the battery cell 20 and the timeliness of the pressure relief can be considered.

[0254] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8 and FIG. 9, in some embodiments, the area enclosed by the weak portion 2421a is a pressure relief area 2422, and the projection area of the pressure relief area 2422 along the thickness direction of the first wall portion 213 is S; wherein, 100mm 2 ≤450mm 2 , and 0.010mm≤H1≤0.160mm; or, 350mm 2 ≤S≤850mm 2 , and 0.015mm≤H1≤0.170mm; or, 750mm 2 ≤S≤1250mm 2 , and 0.020mm≤H1≤0.180mm; or, 1150mm 2 ≤S≤1650mm 2 , and 0.025mm≤H1≤0.190mm; or, 1550mm 2 ≤S≤2100mm 2and 0.030 mm ≤ H1 ≤ 0.200 mm.

[0255] Please refer to FIG. 4, FIG. 6 and FIG. 9, in some embodiments, the thickness direction of the first wall portion 213 is the X direction shown in the figures.

[0256] The pressure relief area 2422 is the area of the pressure relief mechanism 24 enclosed by the weakened portion 2421a, i.e. the area of the pressure relief mechanism 24 inside the weakened portion 2421a. When the battery cell 20 is relieved of pressure, the weakened portion 2421a cracks along the edge of the pressure relief area 2422, so that the pressure relief area 2422 can open to relieve pressure.

[0257] The pressure relief area 2422 includes the above-mentioned raised portion 24221. For example, the pressure relief area 2422 can be locally raised in the direction away from the electrode assembly 23 to form the raised portion 24221, or the pressure relief area 2422 can be entirely raised in the direction away from the electrode assembly 23 to form the raised portion 24221. Please refer to FIG. 6, in the embodiment shown in FIG. 6, the pressure relief area 2422 is entirely raised in the direction away from the electrode assembly 23 to form the raised portion 24221, at this time, the pressure relief area 2422 is the raised portion 24221.

[0258] S represents the projected area of the pressure relief area 2422 in the thickness direction of the first wall portion 213. Please refer to FIG. 9, in FIG. 9, S is marked with a mesh line. It should be noted that here the mesh line is only to facilitate the display of S, and does not represent any physical meaning.

[0259] The projected area of the pressure relief area 2422 in the thickness direction of the first wall portion 213 can be: S = 100 mm 2 , 150 mm 2 , 200 mm 2 , 250 mm 2 , 300 mm 2 , 350 mm 2 , 400 mm 2 , 450 mm 2 , 500 mm 2 , 550 mm 2 , 600 mm 2 , 650 mm 2 , 700 mm 2 , 750 mm 2 , 800 mm 2 , 850 mm 2 , 900 mm 2 , 950 mm 2 , 1000 mm 2 , 1050 mm 2 , 1100 mm 2 , 1150 mm2 1200 mm 2 1250 mm 2 1300 mm 2 1350 mm 2 1400 mm 2 1450 mm 2 1500 mm 2 1550 mm 2 1600 mm 2 1650 mm 2 1700 mm 2 1750 mm 2 1800 mm 2 1850 mm 2 1900 mm 2 1950 mm 2 2000 mm 2 2050 mm 2 2100 mm 2 and so on.

[0260] When 100 mm 2 ≤ S ≤ 450 mm 2 , 0.010 mm ≤ H1≤ 0.160 mm. When 100 mm 2 ≤ S ≤ 450 mm 2 , the minimum thickness of the weak portion 2421a along the thickness direction of the first wall portion 213 can be: 0.010 mm, 0.020 mm, 0.030 mm, 0.040 mm, 0.050 mm, 0.060 mm, 0.070 mm, 0.080 mm, 0.090 mm, 0.100 mm, 0.110 mm, 0.120 mm, 0.130 mm, 0.140 mm, 0.150 mm, 0.160 mm, and so on.

[0261] When the projection area of the pressure relief area 2422 is large, the pressure relief area 2422 is more likely to be broken by the internal pressure, so when the projection area of the pressure relief area 2422 is increased, the thickness of the weak portion 2421a can be increased to ensure the same burst pressure. 2 ≤ S ≤ 450 mm 2 , and H1≥ 0.010 mm, the thickness of the weak portion 2421a is large, and the weak portion 2421a is not easy to be broken in advance due to the change of the internal pressure of the battery monomer 20 or external impact, which is beneficial to reduce the risk of the weak portion 2421a being damaged in advance, and is beneficial to improve the service life of the battery monomer 20. 2 ≤ S ≤ 450 mm 2, and H1≤0.160 mm, the thickness of the weak portion 2421a is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery cell 20 is in thermal runaway, which is conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 100 mm 2 ≤S≤450 mm 2 , and 0.010 mm≤H1≤0.160 mm, the service life of the battery cell 20 and the timeliness of pressure relief can be considered.

[0262] When 350 mm 2 ≤S≤850 mm 2 , 0.015 mm≤H1≤0.170 mm. When 350 mm 2 ≤S≤850 mm 2 , the minimum thickness of the weak portion 2421a along the thickness direction of the first wall portion 213 can be: H1=0.015 mm, 0.020 mm, 0.030 mm, 0.040 mm, 0.050 mm, 0.060 mm, 0.070 mm, 0.080 mm, 0.090 mm, 0.100 mm, 0.110 mm, 0.120 mm, 0.130 mm, 0.140 mm, 0.150 mm, 0.160 mm, 0.170 mm, etc.

[0263] When 350 mm 2 ≤S≤850 mm 2 , and H1≥0.015 mm, the thickness of the weak portion 2421a is large, and the weak portion 2421a is not easy to crack in advance due to the change of the pressure inside the battery cell 20 or external impact, which is conducive to reducing the risk of the weak portion 2421a being damaged in advance, and is conducive to improving the service life of the battery cell 20. When 350 mm 2 ≤S≤850 mm 2 , and H1≤0.170 mm, the thickness of the weak portion 2421a is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery cell 20 is in thermal runaway, which is conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 350 mm 2 ≤S≤850 mm 2 , and 0.015 mm≤H1≤0.170 mm, the service life of the battery cell 20 and the timeliness of pressure relief can be considered.

[0264] When 750 mm 2 ≤S≤1250 mm 2 , 0.020 mm≤H1≤0.180 mm. When 750 mm 2 ≤S≤1250 mm 2When the weak part 2421a has a minimum thickness along the thickness direction of the first wall part 213, it can be: H1 = 0.020mm, 0.030mm, 0.040mm, 0.050mm, 0.060mm, 0.070mm, 0.080mm, 0.090mm, 0.100mm, 0.110mm, 0.120mm, 0.130mm, 0.140mm, 0.150mm, 0.160mm, 0.170mm, 0.180mm, etc.

[0265] When 750mm 2 ≤S≤1250mm 2 When H1 ≥ 0.020 mm, the thickness of the weak part 2421a is relatively large. The weak part 2421a is less likely to crack prematurely due to pressure changes inside the battery cell 20 or external impacts, which helps reduce the risk of premature damage to the weak part 2421a and improves the lifespan of the battery cell 20. When 750 mm... 2 ≤S≤1250mm 2 When H1 ≤ 0.180 mm, the thickness of the weak part 2421a will not be too large, allowing the pressure relief mechanism 24 to open and relieve pressure in a timely manner when the battery cell 20 experiences thermal runaway, thus improving the timeliness of pressure relief by the pressure relief mechanism 24. Therefore, when 750 mm 2 ≤S≤1250mm 2 When 0.020mm≤H1≤0.180mm, the lifespan of the battery cell 20 and the timeliness of pressure relief can be taken into account.

[0266] When 1150mm 2 ≤S≤1650mm 2 When 0.025mm ≤ H1 ≤ 0.190mm. When 1150mm 2 ≤S≤1650mm 2 When the weak part 2421a has a minimum thickness along the thickness direction of the first wall part 213, it can be: H1 = 0.025mm, 0.030mm, 0.040mm, 0.050mm, 0.060mm, 0.070mm, 0.080mm, 0.090mm, 0.100mm, 0.110mm, 0.120mm, 0.130mm, 0.140mm, 0.150mm, 0.160mm, 0.170mm, 0.180mm, 0.190mm, etc.

[0267] When 1150mm 2 ≤S≤1650mm 2, and H1 is greater than or equal to 0.025 mm, the thickness of the weak portion 2421a is relatively large, the weak portion 2421a is not prone to be cracked in advance due to the pressure change inside the battery monomer 20 or external impact, which is beneficial to reduce the risk of the weak portion 2421a being damaged in advance, and is beneficial to improve the service life of the battery monomer 20. When 1150 mm 2 ≤ S ≤ 1650 mm 2 , and H1 is less than or equal to 0.190 mm, the thickness of the weak portion 2421a is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery monomer 20 is out of control, which is beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 1550 mm 2 ≤ S ≤ 2100 mm 2 , and 0.025 mm ≤ H1 ≤ 0.190 mm, the service life and the timeliness of the pressure relief of the battery monomer 20 can be considered.

[0268] When 1550 mm 2 ≤ S ≤ 2100 mm 2 , 0.030 mm ≤ H1 ≤ 0.200 mm. When 1550 mm 2 ≤ S ≤ 2100 mm 2 , the minimum thickness of the weak portion 2421a along the thickness direction of the first wall portion 213 can be: H1 = 0.030 mm, 0.040 mm, 0.050 mm, 0.060 mm, 0.070 mm, 0.080 mm, 0.090 mm, 0.100 mm, 0.110 mm, 0.120 mm, 0.130 mm, 0.140 mm, 0.150 mm, 0.160 mm, 0.170 mm, 0.180 mm, 0.190 mm, 0.200 mm, etc.

[0269] When 1550 mm 2 ≤ S ≤ 2100 mm 2 , and H1 is greater than or equal to 0.030 mm, the thickness of the weak portion 2421a is relatively large, the weak portion 2421a is not prone to be cracked in advance due to the pressure change inside the battery monomer 20 or external impact, which is beneficial to reduce the risk of the weak portion 2421a being damaged in advance, and is beneficial to improve the service life of the battery monomer 20. When 1550 mm 2 ≤ S ≤ 2100 mm 2 , and H1 is less than or equal to 0.200 mm, the thickness of the weak portion 2421a is not too large, so that the pressure relief mechanism 24 can be opened in time when the battery monomer 20 is out of control, which is beneficial to improve the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 1550 mm 2 ≤ S ≤ 2100 mm 2 , and 0.030 mm ≤ H1 ≤ 0.200 mm, the service life and the timeliness of the pressure relief of the battery monomer 20 can be considered.

[0270] In some embodiments, 100 mm 2 ≤ S ≤ 450 mm 2 , and 0.020 mm ≤ H1≤ 0.160 mm; or, 350 mm 2 ≤ S ≤ 850 mm 2 , and 0.025 mm ≤ H1≤ 0.170 mm; or, 750 mm 2 ≤ S ≤ 1250 mm 2 , and 0.030 mm ≤ H1≤ 0.180 mm; or, 1150 mm 2 ≤ S ≤ 1650 mm 2 , and 0.035 mm ≤ H1≤ 0.190 mm; or, 1550 mm 2 ≤ S ≤ 2100 mm 2 , and 0.040 mm ≤ H1≤ 0.200 mm.

[0271] When 100 mm 2 ≤ S ≤ 450 mm 2 , 0.020 mm ≤ H1≤ 0.160 mm. When 100 mm 2 ≤ S ≤ 450 mm 2 , the minimum thickness of the weak portion 2421a in the thickness direction of the first wall portion 213 can be: H1= 0.020 mm, 0.025 mm, 0.030 mm, 0.035 mm, 0.040 mm, 0.045 mm, 0.050 mm, 0.055 mm, 0.060 mm, 0.065 mm, 0.070 mm, 0.075 mm, 0.080 mm, 0.085 mm, 0.090 mm, 0.095 mm, 0.100 mm, 0.105 mm, 0.110 mm, 0.115 mm, 0.120 mm, 0.125 mm, 0.130 mm, 0.135 mm, 0.140 mm, 0.145 mm, 0.150 mm, 0.155 mm, 0.160 mm, etc.

[0272] When 100 mm 2 ≤ S ≤ 450 mm 2 , and H1≥ 0.020 mm, the thickness of the weak portion 2421a is greater, the weak portion 2421a is less likely to be prematurely cracked due to changes in pressure inside the battery cell 20 or external impact, and it is more advantageous to reduce the risk of the weak portion 2421a being prematurely damaged and to improve the life of the battery cell 20. When 100 mm 2 ≤ S ≤ 450 mm 2, and H1≤0.160mm, the thickness of the weak portion 2421a is not too large, so that the pressure relief mechanism 24 can be opened more timely when the battery cell 20 is in thermal runaway, which is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 100mm 2 ≤S≤450mm 2 , and 0.020mm≤H1≤0.160mm, the service life of the battery cell 20 and the timeliness of pressure relief can be better balanced.

[0273] When 350mm 2 ≤S≤850mm 2 , 0.025mm≤H1≤0.170mm. When 350mm 2 ≤S≤850mm 2 , the minimum thickness of the weak portion 2421a along the thickness direction of the first wall portion 213 can be: H1=0.025mm, 0.030mm, 0.035mm, 0.040mm, 0.045mm, 0.050mm, 0.055mm, 0.060mm, 0.065mm, 0.070mm, 0.075mm, 0.080mm, 0.085mm, 0.090mm, 0.095mm, 0.100mm, 0.105mm, 0.110mm, 0.105mm, 0.110mm, 0.115mm, 0.120mm, 0.125mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.155mm, 0.160mm, 0.165mm, 0.170mm, etc.

[0274] When 350mm 2 ≤S≤850mm 2 , and H1≥0.025mm, the thickness of the weak portion 2421a is larger, and the weak portion 2421a is less likely to be prematurely cracked due to changes in internal pressure of the battery cell 20 or external impact, which is more conducive to reducing the risk of premature damage of the weak portion 2421a and improving the service life of the battery cell 20. When 350mm 2 ≤S≤850mm 2 , and H1≤0.170mm, the thickness of the weak portion 2421a is not too large, so that the pressure relief mechanism 24 can be opened more timely when the battery cell 20 is in thermal runaway, which is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 350mm 2 ≤S≤850mm 2 , and 0.025mm≤H1≤0.170mm, the service life of the battery cell 20 and the timeliness of pressure relief can be better balanced.

[0275] When 750mm2 ≤S≤1250mm 2 When 750mm 2 ≤S≤1250mm 2 , the minimum thickness of the weak portion 2421a in the thickness direction of the first wall portion 213 can be: H1=0.030mm, 0.035mm, 0.040mm, 0.045mm, 0.050mm, 0.055mm, 0.060mm, 0.065mm, 0.070mm, 0.075mm, 0.080mm, 0.085mm, 0.090mm, 0.095mm, 0.100mm, 0.105mm, 0.110mm, 0.115mm, 0.120mm, 0.125mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.155mm, 0.160mm, 0.165mm, 0.170mm, 0.175mm, 0.180mm, etc.

[0276] When 750mm 2 ≤S≤1250mm 2 , and H1≥0.030mm, the thickness of the weak portion 2421a is greater, the weak portion 2421a is less likely to be prematurely cracked due to changes in pressure inside the battery monomer 20 or external impact, and it is more conducive to reducing the risk of the weak portion 2421a being prematurely damaged, and more conducive to improving the service life of the battery monomer 20. When 750mm 2 ≤S≤1250mm 2 , and H1≤0.180mm, the thickness of the weak portion 2421a is not too large, so that the pressure relief mechanism 24 can open the pressure relief more timely when the battery monomer 20 is out of control, and it is more conducive to improving the timeliness of the pressure relief of the pressure relief mechanism 24. Therefore, when 750mm 2 ≤S≤1250mm 2 , and 0.030mm≤H1≤0.180mm, the service life and the timeliness of the pressure relief of the battery monomer 20 can be better balanced.

[0277] When 1150mm 2 ≤S≤1650mm 2 , 0.035mm≤H1≤0.190mm. When 1150mm 2 ≤S≤1650mm 2When 1150 mm < S < 1650 mm, and H1 ≥ 0.035 mm, the thickness of the weak portion 2421a is greater, the weak portion 2421a is less likely to be cracked in advance due to the pressure change inside the battery monomer 20 or external impact, and it is more conducive to reducing the risk of the weak portion 2421a being damaged in advance, and more conducive to improving the service life of the battery monomer 20.

[0278] When 1150 mm < S < 1650 mm, and H1 ≥ 0.035 mm, the thickness of the weak portion 2421a is greater, the weak portion 2421a is less likely to be cracked in advance due to the pressure change inside the battery monomer 20 or external impact, and it is more conducive to reducing the risk of the weak portion 2421a being damaged in advance, and more conducive to improving the service life of the battery monomer 20. 2 2 When 1150 mm < S < 1650 mm, and H1 ≥ 0.035 mm, the thickness of the weak portion 2421a is greater, the weak portion 2421a is less likely to be cracked in advance due to the pressure change inside the battery monomer 20 or external impact, and it is more conducive to reducing the risk of the weak portion 2421a being damaged in advance, and more conducive to improving the service life of the battery monomer 20. 2 2 When 1150 mm < S < 1650 mm, and H1 ≥ 0.035 mm, the thickness of the weak portion 2421a is greater, the weak portion 2421a is less likely to be cracked in advance due to the pressure change inside the battery monomer 20 or external impact, and it is more conducive to reducing the risk of the weak portion 2421a being damaged in advance, and more conducive to improving the service life of the battery monomer 20. 2 2 When 1150 mm < S < 1650 mm, and H1 ≥ 0.035 mm, the thickness of the weak portion 2421a is greater, the weak portion 2421a is less likely to be cracked in advance due to the pressure change inside the battery monomer 20 or external impact, and it is more conducive to reducing the risk of the weak portion 2421a being damaged in advance, and more conducive to improving the service life of the battery monomer 20.

[0279] When 1550 mm < S < 2100 mm, and 0.040 mm ≤ H1 ≤ 0.200 mm. When 1550 mm < S < 2100 mm, and 0.040 mm ≤ H1 ≤ 0.200 mm. 2 2 When 1550 mm < S < 2100 mm, and 0.040 mm ≤ H1 ≤ 0.200 mm. When 1550 mm < S < 2100 mm, and 0.040 mm ≤ H1 ≤ 0.200 mm. 2 2 ​​​​​When the weak point 2421a has a minimum thickness along the thickness direction of the first wall portion 213, it can be: H1 = 0.040mm, 0.045mm, 0.050mm, 0.055mm, 0.060mm, 0.065mm, 0.070mm, 0.075mm, 0.080mm, 0.085mm, 0.090mm, 0.095mm, 0.100mm, 0.105mm, 0.110mm, 0.115mm, 0.120mm, 0.1 25mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.125mm, 0.130mm, 0.135mm, 0.140mm, 0.145mm, 0.150mm, 0.155mm, 0.160mm, 0.165mm, 0.170mm, 0.175mm, 0.180mm, 0.185mm, 0.190mm, 0.195mm, 0.200mm, etc.

[0280] When 1550mm 2 ≤S≤2100mm 2 When H1 ≥ 0.040 mm, the thickness of the weak part 2421a is greater, making it less prone to premature cracking due to internal pressure changes or external impacts on the battery cell 20. This reduces the risk of premature damage to the weak part 2421a and improves the lifespan of the battery cell 20. When 1550 mm... 2 ≤S≤2100mm 2 When H1 ≤ 0.200 mm, the thickness of the weak part 2421a will not be too large, allowing the pressure relief mechanism 24 to open more promptly in the event of thermal runaway of the battery cell 20, thus improving the timeliness of pressure relief. Therefore, when 1550 mm 2 ≤S≤2100mm 2 Furthermore, when 0.040mm≤H1≤0.200mm, it is better able to balance the service life of the battery cell 20 and the timeliness of pressure relief.

[0281] Please refer to Figures 3, 4, 5, 6, 7, 8 and 9. In some embodiments, the height of the raised portion 24221 is H3, which satisfies the condition: 0.2mm≤H3≤4.9mm.

[0282] H3 represents the height of the protrusion of the protrusion portion 24221. In some embodiments, the pressure relief mechanism 24 is provided with a pressure relief groove 245, and the position corresponding to the pressure relief groove 245 of the pressure relief mechanism 24 forms a weak portion 2421a. Referring to FIG. 6, when the pressure relief groove 245 is arranged on the side of the pressure relief mechanism 24 away from the electrode assembly 23, the weak portion 2421a has a first surface facing the electrode assembly 23, and the maximum distance from the first surface to the inner surface of the protrusion portion 24221 can be measured as H3. When the pressure relief groove 245 is arranged on the side of the pressure relief mechanism 24 facing the electrode assembly 23, the weak portion 2421a has a second surface away from the electrode assembly 23, and the maximum distance from the second surface to the outer surface of the protrusion portion 24221 can be measured as H3. When the pressure relief mechanism 24 is provided with pressure relief grooves 245 on both sides along the thickness direction of the first wall portion 213, the maximum distance from the opening of the pressure relief groove 245 arranged on the side of the pressure relief mechanism 24 away from the electrode assembly 23 to the outer surface of the protrusion portion 24221 can be measured as H3.

[0283] The height of the protrusion of the protrusion portion 24221 can be: H3 = 0.2 mm, 0.25, 0.3, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 4.9 mm, etc.

[0284] When H3≥0.2 mm, the height of the protrusion of the protrusion portion 24221 is relatively high, so that the deformation of the protrusion portion 24221 is more obvious, and under the same burst pressure, the thickness of the weak portion 2421a is larger, which is beneficial to reduce the risk of the weak portion 2421a being damaged in advance, and is beneficial to improve the service life of the battery monomer 20. When H3≤4.9 mm, the height of the protrusion of the protrusion portion 24221 is not too large, on the one hand, it is beneficial to reduce the occupation of the internal space of the battery device 100 or the battery monomer 20, and improve the energy density of the battery device 100 or the battery monomer 20, on the other hand, it is beneficial to reduce the risk of interference between the protrusion portion 24221 and other components. Therefore, when 0.2 mm≤H3≤4.9 mm, the service life and energy density of the battery monomer 20 can be considered, and the risk of interference between the protrusion portion 24221 and other components can be reduced.

[0285] Optionally, 0.3 mm≤H3≤3 mm.

[0286] The height of the protrusion of the protrusion portion 24221 can be: H3 = 0.3 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, etc.

[0287] When H3≥0.3mm, the bulging height of the bulging part 24221 is higher, so the deformation of the bulging part 24221 is more obvious, and under the same burst pressure, the thickness of the weak part 2421a can be larger, which is conducive to reducing the risk of the weak part 2421a being damaged in advance and improving the service life of the battery monomer 20. When H3≤3mm, the bulging height of the bulging part 24221 is not too large, on the one hand, it is conducive to reducing the occupation of the internal space of the battery device 100 or the battery monomer 20, improving the energy density of the battery device 100 or the battery monomer 20, and on the other hand, it is conducive to reducing the risk of interference between the bulging part 24221 and other components. Therefore, when 0.3mm≤H3≤3mm, the service life and energy density of the battery monomer 20 can be better balanced, and the risk of interference between the bulging part 24221 and other components can be reduced.

[0288] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8 and FIG. 9, in some embodiments, the connecting part 241 is at least partially bulged in a direction facing the inside of the shell 21, and the weak part 2421a is connected to the part of the connecting part 241 closest to the inside of the shell 21.

[0289] The connecting part 241 can be partially bulged in a direction facing the electrode assembly 23, or the connecting part 241 can be entirely bulged in a direction facing the electrode assembly 23. The weak part 2421a is connected to the part of the connecting part 241 closest to the electrode assembly 23.

[0290] Please refer to FIG. 6, in the embodiment shown in FIG. 6, the connecting part 241 includes a first part 2411 and a second part 2412, the first part 2411 is connected to the first wall part 213, and the second part 2412 is bulged in a direction facing the inside of the shell 21 relative to the first part 2411, the weak part 2421a is connected to the second part 2412, and the first part 2411 is arranged around the outside of the second part 2412.

[0291] By making the connecting part 241 at least partially bulged in a direction away from the electrode assembly 23, and connecting the weak part 2421a to the part of the connecting part 241 farthest away from the electrode assembly 23, the weak part 2421a is less likely to be affected when the connecting part 241 is connected to the first wall part 213, which is conducive to maintaining the performance of the weak part 2421a and improving the service life of the battery monomer 20.

[0292] In some embodiments, the bulging height of the connecting part 241 is H4, which satisfies: 0.2mm≤H4≤7mm.

[0293] H4 represents the height of the protrusion of the connecting portion 241. The connecting portion 241 includes a first portion 2411 connected to the first wall portion 213 and a second portion 2412 protruding in a direction toward the inside of the case 21 relative to the first portion 2411, and the weak portion 2421a is connected to the second portion 2412, and the first portion 2411 is provided around the outside of the second portion 2412. The first portion 2411 has a third face facing the electrode assembly 23, and the second portion 2412 has a fourth face facing the electrode assembly 23, and the maximum distance between the third face and the fourth face can be measured as H4.

[0294] The height of the protrusion of the connecting portion 241 can be: H4 = 0.2 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, etc.

[0295] When H4 ≥ 0.2 mm, the height of the protrusion of the connecting portion 241 is large, thereby facilitating reduction of the height of the protrusion portion 24221 beyond the surface of the connecting portion 241 farthest from the electrode assembly 23, reduction of the occupation of the internal space of the battery cell 20 or the battery device 100, and improvement of the energy density of the battery cell 20 or the battery device 100. When H4 ≤ 7 mm, the height of the protrusion of the connecting portion 241 is not too large, thereby facilitating reduction of the manufacturing difficulty and saving of the manufacturing cost. Therefore, when 0.2 mm ≤ H4 ≤ 7 mm, the occupation of the internal space of the battery cell 20 or the battery device 100 by the protrusion portion 24221 can be effectively reduced, and the manufacturing cost of the battery cell 20 can be reduced.

[0296] Optionally, 0.2 mm ≤ H4 ≤ 5 mm.

[0297] The height of the protrusion of the connecting portion 241 can be: H4 = 0.2 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.8 mm, 4 mm, 4.2 mm, 4.5 mm, 4.8 mm, 5 mm, etc.

[0298] When H4≥0.2 mm, the protrusion height of the connecting portion 241 is large, thereby facilitating reduction of the height of the protrusion portion 24221 beyond the surface of the connecting portion 241 farthest from the electrode assembly 23, reduction of the occupation of the internal space of the battery monomer 20 or the battery device 100, and improvement of the energy density of the battery monomer 20 or the battery device 100. When H4≤5 mm, the protrusion height of the connecting portion 241 is not too large, thereby facilitating reduction of the manufacturing difficulty and saving of the manufacturing cost. Therefore, when 0.2 mm≤H4≤5 mm, the occupation of the internal space of the battery monomer 20 or the battery device 100 by the protrusion portion 24221 can be effectively reduced, and the manufacturing cost of the battery monomer 20 can be reduced.

[0299] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8 and FIG. 9. In some embodiments, the connecting portion 241 comprises a first portion 2411 and a second portion 2412, the first portion 2411 is connected to the first wall portion 213, and the second portion 2412 protrudes in a direction towards the inside of the shell 21 relative to the first portion 2411. The weak portion 2421a is connected to the second portion 2412. The first portion 2411 is annularly arranged outside the second portion 2412, and the width of the first portion 2411 is D1, which satisfies: 0.05 mm≤D1≤0.5 mm.

[0300] The first portion 2411 is a portion of the connecting portion 241 for connecting with the first wall portion 213. The second portion 2412 is a portion of the connecting portion 241 protruding relative to the first portion 2411. The second portion 2412 protrudes in a direction towards the inside of the shell 21 relative to the first portion 2411.

[0301] The first portion 2411 is an annular structure annularly arranged outside the second portion 2412.

[0302] D1 represents the width of the first portion 2411. The width of the first portion 2411 can be: D1=0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm.

[0303] When D1≥0.05 mm, the width of the first portion 2411 is large, thereby facilitating connection of the first portion 2411 to the first wall portion 213. When D1≤0.5 mm, the width of the first portion 2411 is not too large, thereby enabling the pressure relief area 2422 defined by the weak portion 2421a to be large, and facilitating improvement of the timeliness of pressure relief of the battery monomer 20. Therefore, when 0.05 mm≤D1≤0.5 mm, the first portion 2411 can be conveniently connected to the first wall portion 213, and the battery monomer 20 can be quickly relieved of pressure.

[0304] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8 and FIG. 9, in some embodiments, the pressure relief mechanism 24 comprises a connecting area 2421 directly connecting the connecting portion 241 and the protruding portion 24221. The weak portion 2421a is arranged on the connecting area 2421, and the width of the connecting area 2421 is D2, which satisfies: 0.3mm≤D2≤2mm.

[0305] The connecting area 2421 is the area directly connecting the connecting portion 241 and the protruding portion 24221 in the pressure relief mechanism 24. The connecting area 2421 can be an annular structure, and the weak portion 2421a is arranged on the connecting area 2421.

[0306] D2 represents the width of the connecting area 2421. The width of the connecting area 2421 can be: D2=0.3mm, 0.5mm, 0.8mm, 1mm, 0.12mm, 1.5mm, 1.8mm, 2mm, etc.

[0307] When D2≥0.3mm, the width of the connecting area 2421 is larger, and it is easier to process the weak portion 2421a on the connecting area 2421. When D2≤2mm, the width of the connecting area 2421 is too large, making it difficult to process and manufacture the connecting area 2421. Therefore, when 0.3mm≤D2≤2mm, it is beneficial to simplify production and reduce production cost.

[0308] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8 and FIG. 9, in some embodiments, the pressure relief mechanism 24 is provided with a pressure relief groove 245, and the weak portion 2421a is formed at the corresponding position of the pressure relief mechanism 24 and the pressure relief groove 245.

[0309] The pressure relief mechanism 24 has a fifth surface and a sixth surface arranged oppositely in the thickness direction of the first wall portion 213. Among them, the fifth surface faces the electrode assembly 23, and the sixth surface faces away from the electrode assembly 23. The sixth surface can be provided with the pressure relief groove 245, or the fifth surface can be provided with the pressure relief groove 245. Taking the sixth surface provided with the pressure relief groove 245 as an example, that is, the pressure relief groove 245 is recessed from the sixth surface to the fifth surface, and the weak portion 2421a is the part between the groove bottom surface of the pressure relief groove 245 and the fifth surface.

[0310] The pressure relief groove 245 can be formed in various ways, such as stamping forming, cold heading forming, etc. Taking the way of stamping forming to form the pressure relief groove 245 as an example, the pressure relief groove 245 can be formed on the pressure relief mechanism 24 along the thickness direction of the first wall portion 213.

[0311] The pressure relief groove 245 is formed by stamping or cold heading, which causes cold work hardening of the groove wall of the pressure relief groove 245 (change in grain arrangement, lattice distortion, reduction in metal plasticity, and increase in material hardness), which enhances the ability to resist external impact and is not easily damaged by external impact. This helps to reduce the risk of liquid leakage of the pressure relief mechanism 24.

[0312] The weak portion 2421a is formed on the pressure relief mechanism 24 by opening the pressure relief groove 245 on the pressure relief mechanism 24, and when the battery cell 20 is relieved, the pressure relief mechanism 24 is broken along at least part of the weak portion 2421a, which is simple, convenient, and low in cost.

[0313] Referring to FIGS. 3, 4, 5, 6, 7, 8, and 9, in some embodiments, the width of the notch of the pressure relief groove 245 is D3, which satisfies 0.02mm≤D3≤0.8mm.

[0314] D3 represents the width of the notch of the pressure relief groove 245. The width of the notch of the pressure relief groove 245 can be 0.02mm, 0.05mm, 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, etc.

[0315] When D3≥0.02mm, the width of the notch of the pressure relief groove 245 is large, so that the width of the weak portion 2421a is large, which can reduce the risk of the weak portion 2421a being broken due to changes in the internal gas pressure of the battery cell 20, and helps to improve the reliability of the battery cell 20. When D3≤0.8mm, the width of the notch of the pressure relief groove 245 is not too large, which helps to cause the weak portion 2421a to break in time when the battery cell 20 is relieved, and helps to improve the timeliness of the relief of the battery cell 20. Therefore, when 0.02mm≤D3≤0.8mm, the width of the notch of the pressure relief groove 245 is moderate, the weak portion 2421a is neither easily broken due to changes in the internal gas pressure of the battery cell 20, nor can it break in time when the battery cell 20 is relieved, which helps to improve the timeliness of the relief of the battery cell 20.

[0316] Alternatively, 0.03mm≤D3≤0.6mm.

[0317] The width of the notch of the pressure relief groove 245 can be: D3 = 0.03 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.25 mm, 0.28 mm, 0.3 mm, 0.32 mm, 0.35 mm, 0.38 mm, 0.4 mm, 0.42 mm, 0.45 mm, 0.48 mm, 0.5 mm, 0.52 mm, 0.55 mm, 0.58 mm, 0.6 mm, etc.

[0318] When D3≥0.03 mm, the width of the notch of the pressure relief groove 245 is larger, so that the width of the weak portion 2421a is larger, which can reduce the risk of the weak portion 2421a cracking due to the change of the gas pressure inside the battery monomer 20, and is beneficial to improve the reliability of the battery monomer 20. When D3≤0.6 mm, the width of the notch of the pressure relief groove 245 is not too large, so as to facilitate the weak portion 2421a to crack in time when the battery monomer 20 is relieved, and is beneficial to improve the timeliness of the pressure relief of the battery monomer 20. Therefore, when 0.03 mm≤D3≤0.6 mm, the width of the notch of the pressure relief groove 245 is more moderate, the weak portion 2421a neither easily cracks due to the change of the gas pressure inside the battery monomer 20, nor can crack in time when the battery monomer 20 is relieved, which is beneficial to improve the timeliness of the pressure relief of the battery monomer 20.

[0319] Please refer to FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8 and FIG. 9, in some embodiments, the thickness of the pressure relief mechanism 24 is H5, which satisfies: 0.05 mm≤H5≤0.5 mm.

[0320] H5 represents the thickness of the pressure relief mechanism 24. It should be noted that the thickness of the pressure relief mechanism 24 refers to the thickness of the pressure relief mechanism 24 at the non-weak position. For example, in the embodiment in which the pressure relief mechanism 24 is provided with the pressure relief groove 245, the thickness of the pressure relief mechanism 24 is the thickness of the area of the pressure relief mechanism 24 except the pressure relief groove 245. When measuring, the average value of multiple measurements can be taken as H5.

[0321] The thickness of the pressure relief mechanism 24 can be: H5 = 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, etc.

[0322] When H5 is greater than or equal to 0.05 mm, the thickness of the pressure relief mechanism 24 is relatively large, the pressure relief mechanism 24 has relatively high structural strength, and the risk of deformation of the pressure relief mechanism 24 under stress can be reduced, which is beneficial to improving the service life and reliability of the battery monomer 20. When H5 is less than or equal to 0.5 mm, the thickness of the pressure relief mechanism 24 is not too large, which is beneficial to controlling the manufacturing cost of the battery monomer 20. Therefore, when 0.05 mm≤H5≤0.5 mm, the service life, reliability and manufacturing cost of the battery monomer 20 can be considered.

[0323] Optionally, 0.05 mm≤H5≤0.3 mm.

[0324] The thickness of the pressure relief mechanism 24 can be: H5=0.05 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.25 mm, 0.28 mm, 0.3 mm, etc.

[0325] When H5 is greater than or equal to 0.05 mm, the thickness of the pressure relief mechanism 24 is relatively large, the pressure relief mechanism 24 has relatively high structural strength, and the risk of deformation of the pressure relief mechanism 24 under stress can be reduced, which is beneficial to improving the service life and reliability of the battery monomer 20. When H5 is less than or equal to 0.3 mm, the thickness of the pressure relief mechanism 24 is not too large, which is more beneficial to controlling the manufacturing cost of the battery monomer 20. Therefore, when 0.05 mm≤H5≤0.3 mm, the service life, reliability and manufacturing cost of the battery monomer 20 can be considered.

[0326] In some embodiments, the pressure relief mechanism 24 is provided separately from the first wall portion 213, the first wall portion 213 is provided with a pressure relief hole 2131, and the pressure relief mechanism 24 is mounted to the first wall portion 213 and covers the pressure relief hole 2131.

[0327] The "pressure relief mechanism 24 is provided separately from the first wall portion 213, the first wall portion 213 is provided with a pressure relief hole 2131, and the pressure relief mechanism 24 is mounted to the first wall portion 213 and covers the pressure relief hole 2131" means that, during manufacturing, the pressure relief hole 2131 is formed on the first wall portion 213, the pressure relief mechanism 24 and the first wall portion 213 are provided separately, and finally connected together. For example, the pressure relief mechanism 24 can be welded to the first wall portion 213. The pressure relief mechanism 24 can be a rupture disc mounted to the first wall portion 213.

[0328] In some embodiments, the pressure relief mechanism 24 is arranged at one end of the pressure relief hole 2131 facing the electrode assembly 23. The battery monomer 20 includes a protective member 26 arranged at one end of the pressure relief hole 2131 away from the electrode assembly 23 and covering the pressure relief hole 2131.

[0329] The pressure relief mechanism 24 is arranged separately from the first wall portion 213 and is mounted to the first wall portion 213, so as to facilitate manufacturing.

[0330] Optionally, the first wall portion 213 is made of iron, and the pressure relief mechanism 24 is welded to the first wall portion 213.

[0331] The first wall portion 213 is made of iron refers to that the material with the largest mass percentage in the material of the first wall portion 213 is iron. For example, the material of the first wall portion 213 can be carbon steel or stainless steel. The carbon steel can be low-carbon steel, medium-carbon steel or high-carbon steel. For example, the material of the first wall portion 213 can be 304 stainless steel, 305 stainless steel, 316 stainless steel, etc.

[0332] The pressure relief mechanism 24 and the first wall portion 213 are both made of iron, which can effectively improve the structural strength of the first wall portion 213 and the pressure relief mechanism 24, reduce the risk of deformation of the first wall portion 213 and the pressure relief mechanism 24 under stress, and is beneficial to reduce the risk of early valve relief of the pressure relief mechanism 24, and is beneficial to improve the service life and reliability of the battery monomer 20. On the other hand, the pressure relief mechanism 24 and the first wall portion 213 are easier to weld, which is beneficial to reduce the phenomenon of welding cracks between the pressure relief mechanism 24 and the end cover 212, thereby reducing the risk of liquid leakage of the battery monomer 20 and improving the reliability of the battery monomer 20.

[0333] In some other embodiments, the pressure relief mechanism 24 is integrally formed with the first wall portion 213.

[0334] Integrally formed refers to that the first wall portion 213 and the pressure relief mechanism 24 are provided as an integral structure. For example, the pressure relief mechanism 24 can be formed on the first wall portion 213 by stamping or cold heading.

[0335] Integrally forming the pressure relief mechanism 24 with the first wall portion 213 eliminates the need for additional welding or bonding processes, which is beneficial to reduce the risk of liquid leakage of the pressure relief mechanism 24. Moreover, during production, it is easy to make the initiation pressure of the processed battery monomer 20 more consistent.

[0336] The application also provides a battery device 100, which comprises the battery monomer 20 described above.

[0337] The application also provides a power consumption device, which comprises the battery monomer 20 described above, and the battery monomer 20 is used to provide electric energy for the power consumption device.

[0338] According to some embodiments of the application, please refer to FIGS. 3-9.

[0339] The battery monomer 20 provided by the embodiment of the present application comprises an outer shell 21 and a pressure relief mechanism 24, the outer shell 21 has a first wall part 213, and the pressure relief mechanism 24 is arranged on the first wall part 213. The base material of the pressure relief mechanism 24 is iron. The pressure relief mechanism 24 comprises a weak part 2421a configured to be at least partially destroyed to release pressure when the pressure inside the outer shell 21 reaches a threshold value, wherein the thinnest region of the weak part 2421a is located at least on both sides of the weak part 2421a in the width direction of the first wall part 213. The base material of the pressure relief mechanism 24 is iron, which can effectively improve the structural strength of the pressure relief mechanism 24, reduce the risk of early valve pressure relief of the pressure relief mechanism 24, and help to improve the service life and reliability of the battery monomer 20. The thinnest region of the weak part 2421a is located at least on both sides of the weak part 2421a in the width direction of the first wall part 213, and when the pressure inside the outer shell 21 reaches the threshold value, the thinnest region of the weak part 2421a cracks first, that is, both sides of the weak part 2421a in the width direction of the first wall part 213 crack first. Therefore, even if the pressure relief area 2422 defined by the weak part 2421a is not completely opened, the high-temperature gas is not easy to diffuse along the width direction of the first wall part 213, and when diffusing along other directions, the high-temperature gas is not easy to diffuse to the other battery monomer 20 adjacent to it, and is not easy to cause thermal runaway of the other battery monomer 20, which helps to improve the reliability of the battery device 100.

[0340] In some embodiments, the weak part 2421a is in a closed ring shape. The minimum thickness of the cross section of the weak part 2421a at any two positions in the extension direction thereof is equal. By making the minimum thickness of the cross section of the weak part 2421a at any two positions in the extension direction thereof equal, when the pressure inside the outer shell 21 reaches the threshold value, the pressure relief mechanism 24 can crack along the entire circumference of the weak part 2421a, so that the pressure relief area 2422 defined by the weak part 2421a can be separated from the pressure relief mechanism 24, and the pressure relief area 2422 is not easy to hang on the pressure relief mechanism 24, not easy to block the gas eruption, which reduces the risk of high-temperature gas being sprayed to the adjacent battery monomer 20, and helps to improve the reliability of the battery monomer 20.

[0341] In some embodiments, the weak portion 2421a is in a closed loop shape, the weak portion 2421a comprises a first weak section 24212 and a second weak section 24213 connected end to end, the thickness of the second weak section 24213 is greater than the thickness of the first weak section 24212, and the second weak section 24213 is located at one side of the weak portion 2421a in the length direction of the first wall portion 213. By arranging the second weak section 24213, the strength of the pressure relief mechanism 24 at the position of the second weak section 24213 is weakened, so that the pressure relief area 2422 is more easily turned open under the action of the internal gas pressure of the battery monomer 20, not only can improve the probability of opening of the pressure relief area 2422, but also can improve the opening speed of the pressure relief area 2422, realize rapid pressure relief, reduce the risk of explosion and fire of the battery monomer 20, and is beneficial to improve the reliability of the battery monomer 20. By locating the second weak section 24213 at one side of the weak portion 2421a in the length direction of the first wall portion 213, even if the pressure relief area 2422 is not completely opened when the battery monomer 20 is pressure relieved, the high-temperature gas sprayed will diffuse towards the length direction of the first wall portion 213 under the action of the pressure relief area 2422, and when diffusing along the length direction of the first wall portion 213, the path to the other battery monomer 20 adjacent to it is farther, that is, the high-temperature gas sprayed is less likely to diffuse to the other battery monomer 20 adjacent to it, and is less likely to cause thermal runaway of the other battery monomer 20, which is beneficial to improve the reliability of the battery device 100.

[0342] In yet some embodiments, the weak portion is in an open shape, and the open end of the weak portion is located at one side of the weak portion in the length direction of the first wall portion. By locating the open end of the weak portion 2421a at one side of the weak portion 2421a in the length direction of the first wall portion 213, when the battery monomer 20 is pressure relieved, the pressure relief area 2422 turns open around the open end, even if the pressure relief area 2422 is not completely opened, the high-temperature gas sprayed will diffuse towards the length direction of the first wall portion 213 under the action of the pressure relief area 2422, and when diffusing along the length direction of the first wall portion 213, the path to the other battery monomer 20 adjacent to it is farther, that is, the high-temperature gas sprayed is less likely to diffuse to the other battery monomer 20 adjacent to it, and is less likely to cause thermal runaway of the other battery monomer 20, which is beneficial to improve the reliability of the battery device 100.

[0343] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A battery cell, wherein, The battery cell comprises: a housing having a first wall portion; a pressure relief mechanism arranged on the first wall portion, a base material of the pressure relief mechanism being iron, the pressure relief mechanism comprising a weak portion configured to be at least partially destroyed to release pressure inside the housing when the pressure reaches a threshold value; a thinnest region of the weak portion is located on both sides of the weak portion in a width direction of the first wall portion.

2. The battery cell of claim 1, wherein, The weak portion is in a closed ring shape, and a difference between minimum thicknesses of cross sections of the weak portion at any two positions in an extension direction of the weak portion is less than 0.01 mm, the cross sections being perpendicular to the extension direction.

3. The battery cell of claim 2, wherein, The minimum thicknesses of the cross sections of the weak portion at any two positions in the extension direction are equal.

4. The battery cell of claim 3, wherein, The minimum thickness of the weak portion is H1, and 0.01 mm≤H1≤0.2 mm is satisfied.

5. The battery cell of claim 4, wherein, 0.01 mm≤H1≤0.15 mm is satisfied.

6. The battery cell of claim 1, wherein, The weak portion is in a closed ring shape, and the weak portion comprises a first weak segment and a second weak segment connected in a head-to-tail manner, a thickness of the second weak segment is greater than a thickness of the first weak segment, and the second weak segment is located on one side of the weak portion in a length direction of the first wall portion.

7. The battery cell of claim 6, wherein, The second weak segment extends along a straight line trajectory.

8. The battery cell of claim 6, wherein, The second weak segment extends along an arc line trajectory.

9. The battery cell of any one of claims 6-8, wherein, The thickness of the first weak segment is H1, the thickness of the second weak segment is H2, and H2-H1≥0.01 mm is satisfied, and optionally, H2-H1≥0.05 mm is satisfied.

10. The battery cell of claim 9, wherein, 0.01 mm≤H1≤0.2 mm is satisfied.

11. The battery cell of claim 9 or 10, wherein, 0.05 mm≤H2≤0.4 mm is satisfied.

12. The battery cell of any one of claims 6-11, wherein, The first weak segment comprises a first segment, a second segment, and a third segment, the first segment, the second segment, the third segment, and the second weak segment are connected in a head-to-tail manner, and the first segment and the third segment are located on both sides of the weak portion in a width direction of the first wall portion.

13. The battery cell of claim 12, wherein, The first segment and / or the third segment extend along a straight line trajectory.

14. The battery cell of claim 1, wherein, The weak portion is in an open shape, and an open end of the weak portion is located on one side of the weak portion in a length direction of the first wall portion.

15. The battery cell of any one of claims 1-14, wherein, The pressure relief mechanism is made of 304 stainless steel, 305 stainless steel, or 316 stainless steel.

16. The battery cell of any one of claims 1-15, wherein, The battery cell comprises an electrode assembly accommodated in the housing. The electrode assembly comprises a positive electrode sheet, the positive electrode sheet comprises a positive electrode active material capable of reversible deintercalation-intercalation of metal ions, and the positive electrode active material comprises a nickel-containing element compound.

17. The battery cell of claim 16, wherein, The nickel-containing element compound comprises a layered lithium-containing transition metal oxide, and a molar amount of nickel element in the layered lithium-containing transition metal oxide accounts for more than 50% of a total molar amount of transition metal elements in the layered lithium-containing transition metal oxide.

18. The battery cell of claim 17, wherein, The molar amount of nickel element in the layered lithium-containing transition metal oxide accounts for more than 80% of the total molar amount of transition metal elements in the layered lithium-containing transition metal oxide.

19. The battery cell of claim 17 or 18, wherein, said layered lithium-containing transition metal oxide comprises Li a Ni b Co c M d O e A f , 0 < a < 1.2, 0.5 < b < 1, optionally 0.9 < b < 1; 0＜c＜1； 0 1 20. The battery cell of any one of claims 1-19, wherein, The pressure relief mechanism comprises a bulge part and a connecting part, the bulge part is located in the area surrounded by the weak part, the connecting part is located outside the weak part and is arranged on the first wall part, and the bulge part is a bulge structure rising in a direction away from the inside of the shell.

21. The battery cell of claim 20, wherein, The boundary of the bulge part at least partially abuts the boundary of the weak part.

22. The battery cell of claim 21, wherein, The boundary of the bulge part completely abuts the boundary of the weak part.

23. The battery cell of any one of claims 20-22, wherein, The minimum thickness of the weak part is H1, and 0.01mm≤H1≤0.2mm is satisfied.

24. The battery cell of claim 23, wherein, The area surrounded by the weak part is a pressure relief area, and the projection area of the pressure relief area along the thickness direction of the first wall part is S. 100 mm 2 ≤ 450 mm 2 and 0.010 mm ≤ H1≤ 0.160 mm; or, 350 mm 2 ≤ S ≤ 850 mm 2 and 0.015 mm ≤ H1 ≤ 0.170 mm; or, 750 mm 2 ≤ S ≤ 1250 mm 2 and 0.020 mm ≤ H1 ≤ 0.180 mm; or, 1150 mm 2 ≤ S ≤ 1650 mm 2 and 0.025 mm ≤ H1 ≤ 0.190 mm; or, 1550 mm 2 ≤ S ≤ 2100 mm 2 and 0.030 mm ≤ H1 ≤ 0.200 mm.

25. The battery cell of claim 24, wherein, 100 mm 2 ≤ S ≤ 450 mm 2 and 0.020 mm ≤ H1 ≤ 0.160 mm; or, 350 mm 2 ≤ S ≤ 850 mm 2 and 0.025 mm ≤ H1 ≤ 0.170 mm; or, 750 mm 2 ≤ S ≤ 1250 mm 2 and 0.030 mm ≤ H1 ≤ 0.180 mm; or, 1150 mm 2 ≤ S ≤ 1650 mm 2 and 0.035 mm ≤ H1 ≤ 0.190 mm; or, 1550 mm 2 ≤ S ≤ 2100 mm 2 and 0.040 mm ≤ H1 ≤ 0.200 mm.

26. The battery cell of any one of claims 20-25, wherein, The bulge height of the bulge part is H3, and 0.2mm≤H3≤4.9mm is satisfied.

27. The battery cell of claim 26, wherein, 0.3mm≤H3≤3mm.

28. The battery cell of any one of claims 20-27, wherein, The connecting part at least partially rises in a direction facing the inside of the shell, and the weak part is connected to the part of the connecting part closest to the inside of the shell.

29. The battery cell of claim 28, wherein, The bulge height of the connecting part is H4, and 0.2mm≤H4≤7mm is satisfied, and optionally, 0.2mm≤H4≤5mm is satisfied.

30. The battery cell of claim 28 or 29, wherein, The connecting part comprises a first part and a second part, the first part is connected to the first wall part, and the second part rises in a direction facing the inside of the shell relative to the first part, and the weak part is connected to the second part. The first part is arranged on the outside of the second part, and the width of the first part is D1, and 0.05mm≤D1≤0.5mm is satisfied.

31. The battery cell of any one of claims 20-30, wherein, The pressure relief mechanism comprises a connecting area, the connecting area directly connects the connecting part and the bulge part, and the weak part is arranged in the connecting area. The width of the connecting area is D2, and 0.3mm≤D2≤2mm is satisfied.

32. The battery cell of any one of claims 1-31, wherein, The pressure relief mechanism is provided with a pressure relief groove, and the position corresponding to the pressure relief mechanism and the pressure relief groove forms the weak part.

33. The battery cell of claim 32, wherein, The width of the slot of the pressure relief groove is D3, and 0.02mm≤D3≤0.8mm is satisfied, and optionally, 0.03mm≤D3≤0.6mm is satisfied.

34. The battery cell of any one of claims 1-33, wherein, The thickness of the pressure relief mechanism is H5, and 0.05mm≤H5≤0.5mm is satisfied, and optionally, 0.05mm≤H5≤0.3mm is satisfied.

35. The battery cell of any one of claims 1-34, wherein, The pressure relief mechanism is separately arranged with the first wall part, the first wall part is provided with a pressure relief hole, the pressure relief mechanism is mounted on the first wall part and covers the pressure relief hole.

36. The battery cell of claim 35, wherein, The base material of the first wall part is iron, and the pressure relief mechanism is welded to the first wall part.

37. The battery cell of any one of claims 1-34, wherein, The pressure relief mechanism is integrally formed with the first wall part.

38. A battery device, wherein, The battery cell comprises the battery cell according to any one of claims 1-37.

39. An electrical device, comprising: The battery cell is used to provide electric energy for the electric device.

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