Battery monomer, battery and electric device

Abstract

The embodiment of the utility model provides a battery monomer, a battery and a power utilization device. Wherein the battery cell comprises: a case; the explosion-proof valve is arranged on the shell; wherein the shell is provided with a weak part, and the weak part is arranged around the anti-explosion valve. In the above embodiment, the weak part is arranged in the surrounding area of the anti-explosion valve, and the weak part can be damaged before other walls or other parts of the shell in the process of thermal runaway in the battery monomer, so that the weak part can be matched with the anti-explosion valve to release pressure, the pressure release rate of the battery monomer is improved, the internal suffocation time of the shell is prevented from being too long, and the service life of the battery monomer is prolonged. Therefore, the safety of the single battery can be improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery cell, a battery, and an electrical device. Background Technology

[0002] In some related technologies, there is a problem of excessively large damage area when batteries experience thermal runaway. Utility Model Content

[0003] Some embodiments of this application propose a battery cell, a battery, and an electrical device to alleviate the problem of excessive damage area in the event of thermal runaway of a battery.

[0004] Some embodiments of this application provide a battery cell, including: a housing; and an explosion-proof valve disposed on the housing; wherein the housing has a weak portion, the weak portion being disposed around the explosion-proof valve.

[0005] In the above embodiments, by setting a weak point in the area around the explosion-proof valve, the weak point can be damaged before other walls or other parts of the casing during the thermal runaway process inside the battery cell. This can then work with the explosion-proof valve to release pressure, increase the pressure release rate of the battery cell, and prevent the internal air entrapment of the casing from being too long and resulting in non-directional pressure release. Therefore, the safety of the battery cell can be improved.

[0006] In some embodiments, the weak portion extends from the location adjacent to the explosion-proof valve in a direction away from the explosion-proof valve.

[0007] In the above embodiments, the weak part extends from the part adjacent to the explosion-proof valve in a direction away from the explosion-proof valve, which enables the weak part to work together with the explosion-proof valve to depressurize the inside of the housing, making the depressurization point more directional and concentrated, and preventing damage to surrounding components caused by the unconcentrated or uncertain direction of depressurization.

[0008] In some embodiments, the thickness of the weak portion is D, which is greater than or equal to 0.2 mm and less than or equal to 1.2 mm.

[0009] In the above embodiments, the smaller D is, the easier it is for the weak part to melt and rupture (the larger the melting and rupture area) during the thermal runaway of the battery cell, and the shorter the gas-filling time inside the casing. However, if D is too small, it will lead to insufficient rigidity of the weak part and a decrease in manufacturing yield. Therefore, D is greater than or equal to 0.2 mm and less than or equal to 1.2 mm, which can ensure that the weak part is damaged before other walls or parts of the casing, and can improve the pressure relief rate of the battery cell in conjunction with the explosion-proof valve, shorten the gas-filling time when thermal runaway occurs inside the casing, while also ensuring that the weak part meets the strength requirements.

[0010] In some embodiments, D is greater than or equal to 0.4 mm and less than or equal to 0.8 mm.

[0011] In the above embodiments, D is further limited to D being greater than or equal to 0.4 mm and less than or equal to 0.8 mm. This allows the structural strength of the weak part to better meet the setting requirements without excessively prolonging the air-holding time, so that the weak part is destroyed within a reasonable time, thereby better cooperating with the explosion-proof valve to improve the pressure relief rate of the battery cell.

[0012] In some embodiments, the distance between the outer edge of the explosion-proof valve in the first direction and the outer edge of the housing in the first direction is a1, the distance between the outer edge of the explosion-proof valve in the first direction and the outer edge of the weak portion in the first direction is a2, and the ratio of a2 to a1 is greater than or equal to 0.2 and less than or equal to 0.6.

[0013] In the above embodiments, the larger the ratio of a2 to a1, the larger the damaged area of ​​the casing, the higher the venting rate, and the shorter the venting time when thermal runaway occurs in a single battery cell. However, the risk of damage to the insulation protection components of the high-voltage connection part of the battery is also higher. Therefore, a ratio of a2 to a1 greater than or equal to 0.2 and less than or equal to 0.6 can both shorten the venting time and reduce the risk of damage to the insulation protection components of the high-voltage connection part of the battery.

[0014] In some embodiments, the ratio of a2 to a1 is greater than or equal to 0.3 and less than or equal to 0.5.

[0015] In the above embodiments, the ratio of a2 to a1 is further limited to greater than or equal to 0.3 and less than or equal to 0.5, which can reduce the risk of damage to the insulation protection of the high-voltage connection part of the battery cell while minimizing the holding time.

[0016] In some embodiments, a1 is greater than or equal to 25 mm and less than or equal to 200 mm; a2 is greater than or equal to 5 mm and less than or equal to 120 mm.

[0017] In the above embodiments, limiting the range of values ​​for a1 and a2 is beneficial to ensure that the ratio of a2 to a1 meets the design requirements, thereby reducing the risk of damage to the insulation protection components of the high-voltage connection part of the battery cell while minimizing the holding time.

[0018] In some embodiments, the distance between the outer edge of the explosion-proof valve in the second direction and the outer edge of the housing in the second direction is b1, the distance between the outer edge of the explosion-proof valve in the second direction and the outer edge of the weak portion in the second direction is b2, and the ratio of b2 to b1 is greater than or equal to 0.3 and less than or equal to 0.8.

[0019] In the above embodiments, the larger the ratio of b2 to b1, the larger the damaged area of ​​the casing, the higher the venting rate, and the shorter the venting time when thermal runaway occurs in a battery cell. However, the risk of damage to adjacent battery cells is also higher. Therefore, a ratio of b2 to b1 greater than or equal to 0.3 and less than or equal to 0.8 can both shorten the venting time and reduce the risk of damage to adjacent battery cells.

[0020] In some embodiments, the ratio of b2 to b1 is greater than or equal to 0.4 and less than or equal to 0.6.

[0021] In the above embodiments, the ratio of b2 to b1 is further limited to greater than or equal to 0.4 and less than or equal to 0.6, which can reduce the risk of damage to adjacent battery cells while minimizing the holding time.

[0022] In some embodiments, b1 is greater than or equal to 5 mm and less than or equal to 50 mm; b2 is greater than or equal to 1.5 mm and less than or equal to 40 mm.

[0023] In the above embodiments, limiting the range of values ​​for b1 and b2 is beneficial to ensure that the ratio of b2 to b1 meets the design requirements, thereby reducing the risk of damage to the insulation protection components of the high-voltage connection part of the battery cell 102 while minimizing the holding time.

[0024] In some embodiments, the wall of the housing where the explosion-proof valve is disposed is a first wall, the thickness of the first wall is D1, the melting point of the material of the first wall is T1, the energy density of the battery cell is E, and the ratio of the product of the square of T1 and D1 to E is greater than or equal to 1000.

[0025] In the above embodiments, by defining the relationship between the melting point T1 of the first wall material, the thickness D1 of the first wall, and the battery energy density E, it is possible to prevent large-area damage to the casing of the battery cell during thermal runaway, thereby improving the safety of the battery cell and helping to control the cost of the battery cell and the battery space utilization rate.

[0026] In some embodiments, the ratio of the product of the square of T1 and the product of D1 to E is greater than or equal to 2000.

[0027] In the above embodiments, the ratio of the product of the square of T1 and D1 to E is further limited to greater than or equal to 2000, which is more conducive to controlling the shell from large-area damage and further improves the safety of the battery cell.

[0028] In some embodiments, T1 is greater than or equal to 600°C and less than or equal to 1700°C; D1 is greater than or equal to 0.4 mm and less than or equal to 4 mm; and E is greater than or equal to 700 Wh / L.

[0029] In the above embodiments, by limiting the range of values ​​for the melting point T1 of the first wall material, the thickness D1 of the first wall, and the battery energy density E, the relationship between the melting point T1 of the first wall material, the thickness D1 of the first wall, and the battery energy density E can meet the preset requirements. This is beneficial to prevent large-area damage to the casing of the battery cell during thermal runaway, and also to control the cost of the battery cell and the battery space utilization rate.

[0030] In some embodiments, the wall of the housing other than the one where the explosion-proof valve is disposed is a second wall, the thickness of the second wall is D2, the melting point of the material of the second wall is T2, the energy density of the battery cell is E, and the ratio of the product of the square of T2 and D2 to E is greater than or equal to 400.

[0031] In the above embodiments, by defining the relationship between the melting point and thickness of the materials of the first wall of the casing and the second wall (other walls) other than the first wall, as well as the energy density of the battery, it is possible to make the battery cell less prone to large-area damage to the casing during thermal runaway, thereby improving the safety of the battery cell and helping to control the cost of the battery cell and the battery space utilization rate.

[0032] In some embodiments, the ratio of the product of the square of T2 and D2 to E is greater than or equal to 600.

[0033] In the above embodiments, the ratio of the product of the square of T2 and D2 to E is further limited to greater than or equal to 600, which is more conducive to controlling the shell from large-area damage and further improves the safety of the battery cell.

[0034] In some embodiments, T2 is greater than or equal to 600°C and less than or equal to 1700°C; D2 is greater than or equal to 0.15 mm and less than or equal to 2 mm; and E is greater than or equal to 700 Wh / L.

[0035] In the above embodiments, by limiting the range of values ​​for the melting point T2 of the second wall material, the thickness D2 of the second wall, and the battery energy density E, the relationship between the melting point T2 of the second wall material, the thickness D2 of the second wall, and the battery energy density E can meet the preset requirements. This is beneficial to prevent large-area damage to the casing of the battery cell during thermal runaway, and also to control the cost of the battery cell and the battery space utilization rate.

[0036] Some embodiments of this application provide a battery comprising the battery cell described above.

[0037] The battery provided in this application includes the battery cell in any of the above embodiments, and has the beneficial effects of the battery cell.

[0038] Some embodiments of this application also provide an electrical device that includes the battery described above.

[0039] The electrical device provided in this application includes the battery in any of the above embodiments, and accordingly possesses the beneficial effects of a battery.

[0040] Based on the above technical solution, this application has at least the following beneficial effects:

[0041] In the above embodiments, by setting a weak point in the area around the explosion-proof valve, the weak point can be damaged before other walls or other parts of the casing during the thermal runaway process inside the battery cell. This can then work with the explosion-proof valve to release pressure, increase the pressure release rate of the battery cell, and prevent the internal air entrapment of the casing from being too long and resulting in non-directional pressure release. Therefore, the safety of the battery cell can be improved. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0043] Figure 1 This is a schematic diagram of the structure of a vehicle disclosed in some embodiments of this application;

[0044] Figure 2 This is an exploded structural diagram of a battery disclosed in some embodiments of this application;

[0045] Figure 3 This is a cross-sectional schematic diagram of a battery cell disclosed in some embodiments of this application;

[0046] Figure 4 This is a top view schematic diagram of a single battery cell disclosed in some embodiments of this application;

[0047] Figure 5 yes Figure 3 An enlarged schematic diagram of the local structure H;

[0048] Figure 6 This is a front view schematic diagram of a battery cell disclosed in the first embodiment of this application;

[0049] Figure 7 yes Figure 6 AA sectional view;

[0050] Figure 8 This is a front view schematic diagram of a battery cell disclosed in the second embodiment of this application;

[0051] Figure 9 yes Figure 8 BB cross-sectional diagram.

[0052] The accompanying drawings are not drawn to scale.

[0053] Marker explanation:

[0054] 1-Housing; 11-First wall; 12-Second wall; 13-Weak part; 2-Explosion-proof valve; 3-Battery cell; 4-Terminal; 5-End plate;

[0055] 100-Battery; 101-Box; 101a-First Box; 101b-Second Box; 102-Battery Cell; 200-Vehicle; 201-Axle; 202-Wheel; 203-Motor; 204-Controller. Detailed Implementation

[0056] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0057] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0058] The directional terms used in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0059] Currently, judging from market trends, the application of power batteries is becoming increasingly widespread. Power batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also widely applied in electric vehicles such as electric motorcycles and electric cars, as well as in aerospace and other fields. With the continuous expansion of power battery applications, market demand is also constantly increasing.

[0060] The battery disclosed in this application can be used as a power source for electrical devices or as an energy storage element in various energy storage systems.

[0061] Electrical devices can include mobile phones, portable devices, laptops, electric vehicles, electric cars, ships, spacecraft, electric toys, and power tools. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft; electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys; power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers.

[0062] For ease of explanation, the following embodiments use a vehicle 200 as an example of an electrical device provided in some embodiments of this application.

[0063] Please refer to Figure 1 , Figure 1This is a schematic diagram of the structure of a vehicle 200 provided in some embodiments of this application. The vehicle 200 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery 100 is disposed inside the vehicle 200, and the battery 100 can be located at the bottom, front, or rear of the vehicle 200. The battery 100 can be used to power the vehicle 200; for example, the battery 100 can serve as the operating power source for the vehicle 200. The vehicle 200 may also include an axle 201, wheels 202 connected to the axle 201, a motor 203, and a controller 204. The motor 203 drives the axle 201 to rotate, the controller 204 controls the operation of the motor 203, and the battery 100 provides electrical energy for the operation of the motor 203 and other components in the vehicle.

[0064] In some embodiments of this application, the battery 100 can not only serve as the operating power source for the vehicle 200, but also as the driving power source for the vehicle 200, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 200.

[0065] Please refer to Figure 2 , Figure 2 This is an exploded structural diagram of a battery 100 provided in some embodiments of this application. The battery 100 includes a housing 101 and a battery cell 102, with the battery cell 102 housed within the housing 101. The housing 101 includes a first housing 101a and a second housing 101b, which overlap each other, defining a space for accommodating the battery cell 102. The second housing 101b may be a hollow structure with one open end, while the first housing 101a may be a plate-like structure, covering the open side of the second housing 101b so that the first housing 101a and the second housing 101b together define the accommodating space. Alternatively, the first housing 101a and the second housing 101b may both be hollow structures with one open end, with the open side of the first housing 101a covering the open side of the second housing 101b. Of course, the box 101 formed by the first box 101a and the second box 101b can be of various shapes, such as a cylinder or a cuboid.

[0066] The battery cell 102 within the housing 101 can be one or more, and these cells can be connected in series, parallel, or in a mixed configuration. A mixed configuration means that some of the battery cells 102 are connected in series while others are connected in parallel. The battery cells 102 can be directly connected in series, parallel, or in a mixed configuration, and then the entire assembly of the battery cells 102 is housed within the housing 101. Alternatively, the battery 100 can also be composed of multiple battery cells 102 first connected in series, parallel, or in a mixed configuration to form a battery module, and then these battery modules are connected in series, parallel, or in a mixed configuration to form a whole, which is then housed within the housing 101. The battery 100 may also include other structures; for example, it may include a busbar component for electrical connection between the multiple battery cells 102.

[0067] The battery cell 102 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited to these. The battery cell 102 can be cylindrical, flat, cuboid, or other shapes.

[0068] refer to Figure 3 In some embodiments, each battery cell 102 includes a housing 1, a battery cell 3, an explosion-proof valve 2, and terminals 4. One or more battery cells 3 can be placed inside the housing 1, and the shape of the housing 1 can be determined based on the shape of the combination of one or more battery cells 3. For example, the housing 1 can be a hollow cuboid, cube, or cylinder, and one side of the housing 1 has an opening to allow one or more battery cells 3 to be placed inside the housing 1. The housing 1 includes an end plate 5. The end plate 5 can be provided on the opening side of the housing 1, and the end plate 5 closes the opening of the housing 1.

[0069] The battery cell 3 is formed by winding electrode sheets and a separator. Two tabs are formed on the battery cell 3. The two tabs are the positive tab and the negative tab, respectively. The end plate 5 is provided with two terminals 4, which are the positive terminal and the negative terminal, respectively. The positive terminal is connected to the positive tab, and the negative terminal is connected to the negative tab.

[0070] Explosion-proof valve 2 can be installed on end plate 5 (see reference). Figure 3 and Figure 6 Of course, it can also be installed on the housing 1. For example, the explosion-proof valve 2 can be installed on the wall of the housing 1 opposite to the end plate 5, generally on the bottom wall of the housing 1 (see reference). Figure 8 When thermal runaway occurs inside the casing 1, such as an electrical short circuit or a sudden accident like cell explosion, the cell will release a large amount of gas, and the temperature and pressure inside the casing 1 will increase rapidly. At this time, the high-temperature gas and gas-solid mixture will be quickly discharged to the outside through the explosion-proof valve 2 to avoid battery explosion or other more serious accidents.

[0071] For the embodiment where the explosion-proof valve 2 is located on the end plate 5: due to the space limitations of the tabs, adapter plates, and poles, the area of ​​the explosion-proof valve 2 cannot be made too large. For the embodiment where the explosion-proof valve 2 is located on the opposite side of the end plate 5, due to the requirements for the adhesive coating area or water-cooling area of ​​the bottom wall of the housing 1, the area of ​​the explosion-proof valve 2 also cannot be made too large.

[0072] Because batteries with high energy density have a thermal runaway gas production rate of ≥1.8L / Ah and a gas production rate of ≥35L / s, they are prone to gas production rate exceeding gas exhaust rate due to insufficient pressure relief area of ​​explosion-proof valve 2. This leads to a continuous increase in internal gas pressure and prolonged gas stagnation, resulting in non-directional pressure relief problems such as large-area rupture of casing 1 or explosion of end plate 5, which further leads to thermal diffusion at the 100-layer level of the battery.

[0073] Based on this, some embodiments of this application provide a battery cell 102, which has a weak part 13 in the area around the explosion-proof valve 2 of the housing 1. During the thermal runaway of the battery cell 102, the weak part 13 can be destroyed, which, together with the explosion-proof valve 2, increases the pressure relief area of ​​the battery cell 102, improves the pressure relief rate, prevents the battery from being trapped for too long, and prevents non-directional pressure relief problems such as the end plate 5 from bursting, thereby improving the safety of the battery.

[0074] refer to Figure 3 and Figure 4 In some embodiments, the battery cell 102 includes a housing 1 and an explosion-proof valve 2.

[0075] The explosion-proof valve 2 is located in the housing 1.

[0076] The housing 1 has a weak part 13, which surrounds the explosion-proof valve 2.

[0077] In the above embodiment, by setting a weak part 13 in the area around the explosion-proof valve 2, the weak part 13 can be damaged before other walls or other parts of the housing 1 during the thermal runaway process inside the battery cell 102. This can then work with the explosion-proof valve 2 to release pressure, increase the pressure release rate of the battery cell 102, and prevent the internal air entrapment of the housing 1 from being too long and causing non-directional pressure release. Therefore, the safety of the battery cell 102 can be improved.

[0078] In some embodiments, the weak portion 13 is annular and is arranged around the explosion-proof valve 2.

[0079] In some embodiments, the weak portion 13 extends from the portion adjacent to the explosion-proof valve 2 in a direction away from the explosion-proof valve 2.

[0080] In the above embodiment, the weak part 13 extends from the part adjacent to the explosion-proof valve 2 in a direction away from the explosion-proof valve 2, so that the weak part 13 and the explosion-proof valve 2 can work together to depressurize the inside of the housing 1, making the depressurization location more directional and concentrated, and preventing damage to the surrounding environment and components due to the non-concentrated or uncertain depressurization direction.

[0081] refer to Figure 5 In some embodiments, the thickness of the weak portion 13 is D, where D is greater than or equal to 0.2 mm and less than or equal to 1.2 mm.

[0082] In the above embodiments, the smaller D is, the easier it is for the weak part 13 to melt and rupture (the larger the melting and rupture area) during the thermal runaway of the battery cell 102, and the shorter the gas-filling time inside the casing 1. However, if D is too small, the rigidity of the weak part 13 will be insufficient, and the manufacturing yield will be reduced. Therefore, D is greater than or equal to 0.2 mm and less than or equal to 1.2 mm, which can ensure that the weak part 13 is damaged before other walls or parts of the casing 1, thereby improving the pressure relief rate of the battery cell 102 in conjunction with the explosion-proof valve 2 and shortening the gas-filling time when thermal runaway occurs inside the casing 1, while also ensuring that the weak part 13 meets the strength requirements.

[0083] In some embodiments, D is greater than or equal to 0.4 mm and less than or equal to 0.8 mm.

[0084] In the above embodiment, D is further limited to D greater than or equal to 0.4 mm and less than or equal to 0.8 mm, which can make the structural strength of the weak part 13 more in line with the setting requirements, without excessively prolonging the air-holding time, so that the weak part 13 is destroyed within a reasonable time, thereby better cooperating with the explosion-proof valve 2 to improve the pressure relief rate of the battery cell 102.

[0085] The wall of the housing 1 where the explosion-proof valve 2 is installed is the first wall 11, and the thickness of the first wall 11 is D1, where D1 is greater than D.

[0086] refer to Figure 4 In some embodiments, the distance between the outer edge of the explosion-proof valve 2 in the first direction X and the outer edge of the housing 1 in the first direction X is a1, and the distance between the outer edge of the explosion-proof valve 2 in the first direction X and the outer edge of the weak part 13 in the first direction X is a2. The ratio of a2 to a1 is greater than or equal to 0.2 and less than or equal to 0.6.

[0087] In the above embodiments, the larger the ratio of a2 to a1, the larger the damaged area of ​​the casing 1 when thermal runaway occurs in the battery cell 102, the higher the venting rate, and the shorter the venting time. However, the risk of damage to the insulation protection components of the high-voltage connection part of the battery is also higher. Therefore, a ratio of a2 to a1 greater than or equal to 0.2 and less than or equal to 0.6 can both shorten the venting time and reduce the risk of damage to the insulation protection components of the high-voltage connection part of the battery.

[0088] In the above embodiment, the explosion-proof valve 2 is disposed on the first wall 11 of the housing 1. The first wall 11 is rectangular, and the first direction X can be the length direction of the first wall 11. Alternatively, the first direction X is the width direction of the battery cell 102.

[0089] In some embodiments, the ratio of a2 to a1 is greater than or equal to 0.3 and less than or equal to 0.5.

[0090] In the above embodiments, the ratio of a2 to a1 is further limited to greater than or equal to 0.3 and less than or equal to 0.5, which can reduce the risk of damage to the insulation protection of the high-voltage connection part of the battery cell 102 while minimizing the holding time.

[0091] In some embodiments, a1 is greater than or equal to 25 mm and less than or equal to 200 mm; a2 is greater than or equal to 5 mm and less than or equal to 120 mm.

[0092] In the above embodiments, limiting the range of values ​​for a1 and a2 is beneficial to ensure that the ratio of a2 to a1 meets the design requirements, thereby reducing the risk of damage to the insulation protection components of the high-voltage connection portion of the battery cell 102 while minimizing the holding time.

[0093] In some embodiments, the distance between the outer edge of the explosion-proof valve 2 in the second direction Y and the outer edge of the housing 1 in the second direction Y is b1, and the distance between the outer edge of the explosion-proof valve 2 in the second direction Y and the outer edge of the weak part 13 in the second direction Y is b2. The ratio of b2 to b1 is greater than or equal to 0.3 and less than or equal to 0.8.

[0094] In the above embodiments, the larger the ratio of b2 to b1, the larger the damaged area of ​​the casing 1, the higher the venting rate, and the shorter the venting time when thermal runaway occurs in the battery cell 102. However, the risk of damage to adjacent battery cells 102 is also higher. Therefore, a ratio of b2 to b1 greater than or equal to 0.3 and less than or equal to 0.8 can both shorten the venting time and reduce the risk of damage to adjacent battery cells 102.

[0095] In the above embodiment, the explosion-proof valve 2 is disposed on the first wall 11 of the housing 1. The first wall 11 is rectangular, and the second direction Y can be the width direction of the first wall 11. Alternatively, the second direction Y is the thickness direction of the battery cell 102.

[0096] In some embodiments, the ratio of b2 to b1 is greater than or equal to 0.4 and less than or equal to 0.6.

[0097] In the above embodiments, the ratio of b2 to b1 is further limited to greater than or equal to 0.4 and less than or equal to 0.6, which can reduce the risk of damage to adjacent battery cells 102 while minimizing the holding time.

[0098] In some embodiments, b1 is greater than or equal to 5 mm and less than or equal to 50 mm; b2 is greater than or equal to 1.5 mm and less than or equal to 40 mm.

[0099] In the above embodiments, limiting the range of values ​​for b1 and b2 is beneficial to ensure that the ratio of b2 to b1 meets the design requirements, thereby reducing the risk of damage to the insulation protection components of the high-voltage connection part of the battery cell 102 while minimizing the holding time.

[0100] In some embodiments, the distance between the outer edge of the explosion-proof valve 2 in the first direction X and the outer edge of the housing 1 in the first direction X is a1, and the distance between the outer edge of the explosion-proof valve 2 in the second direction Y and the outer edge of the housing 1 in the second direction Y is b1, where a1 is greater than b1; wherein the first direction X intersects the second direction Y.

[0101] In the above embodiment, the explosion-proof valve 2 is disposed on the first wall 11 of the housing 1. The first wall 11 is rectangular, and the first direction X can be the length direction of the first wall 11. Alternatively, the first direction X is the width direction of the battery cell 102. The second direction Y can be the width direction of the first wall 11. Alternatively, the second direction Y is the thickness direction of the battery cell 102. The direction from the end plate 5 of the battery cell 102 to the bottom wall of the housing 1 on the opposite side is the height direction of the battery cell 102.

[0102] In some embodiments, the distance between the outer edge of the explosion-proof valve 2 in the first direction X and the outer edge of the weak portion 13 in the first direction X is a2, and the distance between the outer edge of the explosion-proof valve 2 in the second direction Y and the outer edge of the weak portion 13 in the second direction Y is b2, where a2 is greater than b2.

[0103] In some specific embodiments, the explosion-proof valve 2 is disposed on the first wall 11 of the housing 1. The first wall 11 is rectangular, and the first direction X can be the length direction of the first wall 11. Alternatively, the first direction X is the width direction of the battery cell 102. The second direction Y can be the width direction of the first wall 11. Alternatively, the second direction Y is the thickness direction of the battery cell 102.

[0104] In some specific embodiments, along the thickness direction of the battery cell 102, the distance between the edge of the explosion-proof valve 2 and the edge of the weak part 13 is b2, and the distance between the edge of the explosion-proof valve 2 and the edge of the housing 1 is b1. The following conditions are met between b2 and b1: 0.3≤b2 / b1≤0.8, preferably 0.4≤b2 / b1≤0.6, and 5 mm≤b1≤50 mm, 1.5 mm≤b2≤40 mm.

[0105] In the above embodiments, the larger the ratio of b2 to b1, the larger the damaged area of ​​the casing 1, the greater the exhaust rate, and the shorter the suffocation time when the battery experiences thermal runaway, but the higher the risk of damage to adjacent battery cells 102.

[0106] The following is an example of a thermal runaway test method for a single battery cell (102):

[0107] 1. Select a heating plate according to the size of the battery cell 102. The size of the heating plate should cover the large surface of the battery cell 102 as much as possible (coverage area ≥ 60%). The large surface of the battery cell 102 is the surface of the battery cell 102 that extends along the width and height directions.

[0108] 2. Before testing, charge the battery cell 102 to 100% SOC and ensure that the temperature of the battery cell 102 is 25±5℃.

[0109] 3. Sensor Arrangement: 1) Temperature Sensing Wire Arrangement: Apply a layer of Teflon to the center area of ​​each of the two large surfaces of the battery cell 102, arrange the temperature sensing wire on top of the Teflon, and then apply another layer of Teflon; 2) Voltage Sampling Wire Arrangement: Apply a layer of Teflon to the positive terminal, negative terminal, and outer casing of the battery cell 102, arrange the voltage sampling wire on top of the Teflon, and then apply another layer of Teflon; 3) Gas Tube Arrangement: Drill a hole in the first wall 11 of the casing 1 of the battery cell 102, insert the gas tube into the hole and seal it, and connect the gas tube to the pressure sensor; 4) Connect the temperature sensing wire, voltage sampling wire, and pressure sensor to the data acquisition instrument to collect and analyze data in real time. The data acquisition instrument's acquisition frequency is ≤0.1s.

[0110] 4. Assemble the fixture: Ensure the fixture completely covers the large surface of the battery cell 102, with a clamping force of 3000N. Note: The arrangement sequence of the fixture, heating plate, and battery cell 102 is: fixture + heating plate + battery cell + fixture.

[0111] 5. Test: Turn on the data acquisition instrument to collect temperature, voltage and air pressure data, and then turn on the heating plate at 500W to heat the battery cell 102 until the battery cell 102 thermally runs away.

[0112] 6. Obtain the pressure holding time of battery cell 102. Based on the temperature, voltage, and air pressure data collected by the data acquisition instrument, determine the thermal runaway moment and the valve opening moment, and calculate the pressure holding time of battery cell 102 according to the formula: pressure holding time = valve opening moment - thermal runaway moment.

[0113] Thermal runaway determination criteria: a) The triggering object generates a voltage drop, which drops to more than 25% of the initial voltage; b) The temperature at the detection point reaches the maximum operating temperature specified by the manufacturer; c) The temperature rise rate at the detection point, dT / dt, is ≥1℃ / s and lasts for more than 3s.

[0114] When a) and c) or b) and c) occur, thermal runaway is determined, and the moment of thermal runaway is identified.

[0115] Valve opening time determination: When the air pressure drops by more than 25%, it can be determined that the valve has been opened. The moment when the air pressure begins to drop is the valve opening time.

[0116] Both the valve opening moment and the thermal runaway moment can be obtained from the data acquisition unit.

[0117] Table 1 shows the technical effects of the battery performance under different designs. In Comparative Example 1, b2 / b1 is less than the minimum value, resulting in an excessively long internal pressure buildup time during battery thermal runaway, leading to the explosion of the top end plate 5. In Comparative Example 2, b2 / b1 is greater than the maximum value, the area of ​​the weak part 13 is too large, and the battery thermal runaway ejection material damages the explosion-proof valve of the adjacent battery cell 102.

[0118] Table 1

[0119]

[0120] In some specific embodiments, along the width direction of the battery cell 102, the distance between the edge of the explosion-proof valve 2 and the edge of the weak part 13 is a2, and the distance between the edge of the explosion-proof valve 2 and the edge of the housing 1 is a1. The following conditions are met between a2 and a1: 0.2≤a2 / a1≤0.6, preferably 0.3≤a2 / a1≤0.5, and 25mm≤a1≤200mm, 5mm≤a2≤120mm.

[0121] In the above embodiments, the larger a2 / a1 is, the larger the damaged area of ​​the casing 1 will be when the battery experiences thermal runaway, the greater the exhaust rate will be, and the shorter the suffocation time will be. However, the risk of damage to the insulating protective components of the high-voltage connection of the battery will be higher.

[0122] Table 2 shows the technical effects of the battery performance under different designs. In Comparative Example 1, a2 / a1 was less than the minimum value, resulting in an excessively long internal pressure buildup time during battery thermal runaway, leading to the bursting of the top end plate 5. In Comparative Example 2, a2 / a1 was greater than the maximum value, and the area of ​​the weak part 13 was too large. The battery thermal runaway ejection valve damaged the insulation protection component of the high-voltage connection, causing the insulation protection component to fail.

[0123] Table 2

[0124]

[0125] In some specific embodiments, the thickness D of the shell material in the area where the weak part 13 is located satisfies: 0.2 mm ≤ D ≤ 1.2 mm, preferably 0.4 ≤ D ≤ 0.8 mm.

[0126] In the above embodiments, the smaller D is, the easier it is for the weak part 13 to melt and break during the thermal runaway process (the larger the melting and breaking area), and the shorter the gas-holding time. However, if D is too small, it will lead to insufficient local stiffness of the weak part 13, and reduce the manufacturing yield.

[0127] Table 3 shows the technical effects of battery performance under different designs. In Comparative Example 1, D is less than the minimum value, resulting in a battery process yield of less than 90%. In Comparative Example 2, D is greater than the maximum value, resulting in excessively long internal pressure build-up time during thermal runaway, leading to the problem of the top end plate 5 bursting open.

[0128] Table 3

[0129]

[0130] In some related technologies, high-energy-density batteries require a thermal runaway valve temperature ≥1000℃, a valve release time ≤12s, cell weight loss ≥70%, gas production ≥1.8L / Ah, gas production rate ≥35L / s, and energy density ≥700Wh / L. When the battery casing's thermal shock resistance is insufficient, it can lead to large-area damage to the casing under the impact of high-temperature, high-speed airflow and particulate matter during thermal runaway, resulting in thermal diffusion at the battery pack level.

[0131] Based on this, refer to Figure 5 , Figure 7 and Figure 9 In some embodiments, the wall of the housing 1 where the explosion-proof valve 2 is located is a first wall 11, the thickness of the first wall 11 is D1, the melting point of the material of the first wall 11 is T1, the energy density of the battery is E, and the ratio of the product of the square of T1 and D1 to E is greater than or equal to 1000.

[0132] In the above embodiments, by defining the relationship between the material melting point T1 of the first wall 11, the thickness D1 of the first wall 11, and the battery energy density E, it is possible to prevent large-area damage to the casing 1 during the thermal runaway of the battery cell 102, thereby improving the safety of the battery cell 102 and helping to control the cost of the battery cell 102 and the battery space utilization rate.

[0133] For high-energy-density batteries, by limiting the relationship between the melting point T1 of the material of the first wall 11, the thickness D1 of the first wall 11, and the energy density E of the battery, it is more conducive to solving the problem of large-area damage to the casing 1 and improving safety.

[0134] In some embodiments, the ratio of the product of the square of T1 and D1 to E is greater than or equal to 2000.

[0135] In the above embodiment, the ratio of the product of the square of T1 and D1 to E is further limited to greater than or equal to 2000, which is more conducive to controlling the shell 1 from large-area damage and further improves the safety of the battery cell 102.

[0136] In some embodiments, T1 is greater than or equal to 600°C and less than or equal to 1700°C; D1 is greater than or equal to 0.4 mm and less than or equal to 4 mm; E is greater than or equal to 700 Wh / L.

[0137] In the above embodiments, by limiting the range of the material melting point T1 of the first wall 11, the thickness D1 of the first wall 11, and the battery energy density E, the relationship between the material melting point T1 of the first wall 11, the thickness D1 of the first wall 11, and the battery energy density E can meet the preset requirements. This is beneficial to prevent large-area damage to the casing 1 during the thermal runaway of the battery cell 102, and also beneficial to control the cost of the battery cell 102 and the battery space utilization rate.

[0138] refer to Figure 7 and Figure 9 In some embodiments, the wall of the housing 1 that is not equipped with the explosion-proof valve 2 is a second wall 12, the thickness of the second wall 12 is D2, the melting point of the material of the second wall 12 is T2, the energy density of the battery is E, and the ratio of the product of the square of T2 and D2 to E is greater than or equal to 400.

[0139] In the above embodiments, by defining the relationship between the melting point and thickness of the materials of the first wall 11 of the casing 1 and the second wall 12 (other walls) other than the first wall 11 and the energy density of the battery, it is possible to make the battery cell 102 less prone to large-area damage to the casing 1 during thermal runaway, thereby improving the safety of the battery cell 102 and helping to control the cost of the battery cell 102 and the battery space utilization rate.

[0140] For high-energy-density batteries, by defining the relationship between the melting point and thickness of the materials of the first wall 11 and the second wall 12 (other walls) of the casing 1 and the energy density of the battery, it is more conducive to mitigating the problem of large-area damage to the casing 1 and improving safety.

[0141] In some embodiments, the ratio of the product of the square of T2 and D2 to E is greater than or equal to 600.

[0142] In the above embodiment, the ratio of the product of the square of T2 and D2 to E is further limited to greater than or equal to 600, which is more conducive to controlling the shell 1 from large-area damage and further improves the safety of the battery cell 102.

[0143] In some embodiments, T2 is greater than or equal to 600°C and less than or equal to 1700°C; D2 is greater than or equal to 0.15 mm and less than or equal to 2 mm; E is greater than or equal to 700 Wh / L.

[0144] In the above embodiments, by limiting the range of values ​​for the material melting point T2 of the second wall 12, the thickness D2 of the second wall 12, and the battery energy density E, the relationship between the material melting point T2 of the second wall 12, the thickness D2 of the second wall 12, and the battery energy density E can meet the preset requirements. This is beneficial to prevent large-area damage to the casing 1 during the thermal runaway of the battery cell 102, and also beneficial to control the cost of the battery cell 102 and the battery space utilization rate.

[0145] In some specific embodiments, the battery includes an explosion-proof valve, and the surface where the explosion-proof valve is located is the first wall 11. The melting point T1 of the material of the first wall 11, the thickness D1 of the first wall 11, and the energy density E of the battery satisfy the following conditions: T1²*D1 / E ≥ 1000, preferably T1²*D1 / E ≥ 2000; and 600 ≤ T1 ≤ 1700℃, 0.4 ≤ D1 ≤ 4 mm, and E ≥ 700 Wh / L. Among these, T1, D1, and T1²*D1 / E must simultaneously meet the requirements.

[0146] The higher the battery energy density, the higher the temperature of the thermal runaway ejector valve, the faster the gas generation rate, and the more material is ejected (greater weight loss), thus placing higher demands on the thermal shock resistance of the casing. The casing's thermal shock resistance is affected by the material's melting point and wall thickness, with the melting point having a greater influence. A higher material melting point results in stronger thermal shock resistance, but also higher material costs for the same volume. Conversely, thicker casing walls result in stronger thermal shock resistance, but lower battery space utilization and higher material costs.

[0147] Table 4 shows the technical performance of the battery under different designs of the first wall 11. The material with a melting point of 630℃ is aluminum, the material with a melting point of 1500℃ is steel, and the material with a melting point of 1660℃ is titanium.

[0148] Table 4

[0149]

[0150] According to Table 4, in Example 1, T1²*D1 / E is less than the minimum value, leading to thermal runaway, and the damaged area of ​​the first wall 11 accounts for more than 10% of the total area of ​​the first wall 11. In Example 3, D1 is greater than the maximum value, resulting in a battery space utilization rate of <80%. In Example 7, both D1 and T1²*D1 / E are less than the minimum value, causing the damaged area of ​​the first wall 11 to account for more than 10% of the total area of ​​the first wall 11 during the thermal runaway process.

[0151] Because the battery ejects material from the explosion-proof valve during thermal runaway, the thermal shock resistance requirement of the first wall 11 is higher than that of the other walls.

[0152] In some specific embodiments, the wall of the housing 1 that is not equipped with the explosion-proof valve 2 is a second wall 12. The melting point T2 of the material of the second wall 12, the thickness D2 of the second wall 12, and the battery energy density E satisfy the following conditions: T2²*D2 / ≥400, preferably T2²*D2 / E≥600, and 600≤T2≤1700℃, 0.15≤D2≤2mm, and E≥700Wh / L. Among these, T2, D2, and T2²*D2 / E must simultaneously meet the requirements.

[0153] Table 5 shows the technical performance of the battery under different designs for the second wall 12. Aluminum has a melting point of 630℃, steel has a melting point of 1500℃, and titanium has a melting point of 1660℃.

[0154] Table 5

[0155]

[0156] According to Table 5, in Example 1, T2²*D2 / E is less than the minimum value, resulting in the damaged area of ​​the second wall 12 during the thermal runaway process exceeding 10% of the total area of ​​the second wall 12. In Example 3, D2 is greater than the maximum value, resulting in a battery space utilization rate of <80%. In Example 7, both D2 and T2²*D2 / E are less than the minimum value, resulting in the damaged area of ​​the second wall 12 during the thermal runaway process exceeding 10% of the total area of ​​the second wall 12.

[0157] refer to Figure 6 and Figure 7 The explosion-proof valve 2 can be installed on the end plate 5. The end plate 5 is the first wall 11 with a thickness of D1. The other walls of the housing 1 besides the first wall 11 are the second wall 12 with a thickness of D2, which is less than D1.

[0158] refer to Figure 8 and Figure 9 The explosion-proof valve 2 can be installed on the wall of the housing 1 opposite to the end plate 5, that is, the explosion-proof valve 2 is installed on the second wall 12. The thickness of the first wall 11 is D1, and the other walls of the housing 1 other than the first wall 11 are the second wall 12. The thickness of the second wall 12 is D2, and D2 is less than D1.

[0159] Some embodiments of this application also provide a battery comprising the battery cell of any of the above embodiments.

[0160] The battery provided in this application includes the battery cell in any of the above embodiments, and has the beneficial effects of the battery cell.

[0161] Some embodiments of this application also provide an electrical device that includes the battery in any of the above embodiments.

[0162] The electrical device provided in this application includes the battery in any of the above embodiments, and accordingly possesses the beneficial effects of a battery.

[0163] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that, include: Shell (1); as well as Explosion-proof valve (2) is provided in the housing (1); The housing (1) is provided with a weak part (13), which is arranged around the explosion-proof valve (2); The distance between the outer edge of the explosion-proof valve (2) in the first direction (X) and the outer edge of the housing (1) in the first direction (X) is a1, and the distance between the outer edge of the explosion-proof valve (2) in the first direction (X) and the outer edge of the weak part (13) in the first direction (X) is a2. The ratio of a2 to a1 is greater than or equal to 0.2 and less than or equal to 0.

6.

2. The battery cell according to claim 1, characterized in that, The weak part (13) extends from the part adjacent to the explosion-proof valve (2) in a direction away from the explosion-proof valve (2).

3. The battery cell according to claim 1, characterized in that, The thickness of the weak part (13) is D, which is greater than or equal to 0.2 mm and less than or equal to 1.2 mm.

4. The battery cell according to claim 3, characterized in that, The diameter D is greater than or equal to 0.4 mm and less than or equal to 0.8 mm.

5. The battery cell according to claim 1, characterized in that, The ratio of a2 to a1 is greater than or equal to 0.3 and less than or equal to 0.

5.

6. The battery cell according to claim 1 or 5, characterized in that, a1 is greater than or equal to 25 mm and less than or equal to 200 mm; a2 is greater than or equal to 5 mm and less than or equal to 120 mm.

7. The battery cell according to claim 1, characterized in that, The distance between the outer edge of the explosion-proof valve (2) in the second direction (Y) and the outer edge of the housing (1) in the second direction (Y) is b1, and the distance between the outer edge of the explosion-proof valve (2) in the second direction (Y) and the outer edge of the weak part (13) in the second direction (Y) is b2. The ratio of b2 to b1 is greater than or equal to 0.3 and less than or equal to 0.

8.

8. The battery cell according to claim 7, characterized in that, The ratio of b2 to b1 is greater than or equal to 0.4 and less than or equal to 0.

6.

9. The battery cell according to claim 7 or 8, characterized in that, The b1 is greater than or equal to 5 mm and less than or equal to 50 mm; the b2 is greater than or equal to 1.5 mm and less than or equal to 40 mm.

10. The battery cell according to claim 1, characterized in that, The shell (1) is provided with the explosion-proof valve (2) as a first wall (11), the thickness of the first wall (11) is D1, the melting point of the material of the first wall (11) is T1, the energy density of the battery cell is E, and the ratio of the product of the square of T1 and D1 to E is greater than or equal to 1000.

11. The battery cell according to claim 10, characterized in that, The ratio of the square of T1 to the product of D1 and E is greater than or equal to 2000.

12. The battery cell according to claim 10 or 11, characterized in that, The T1 is greater than or equal to 600℃ and less than or equal to 1700℃; the D1 is greater than or equal to 0.4 mm and less than or equal to 4 mm; the E is greater than or equal to 700 Wh / L.

13. The battery cell according to claim 1, characterized in that, The shell (1) is not the wall of the explosion-proof valve (2) which is the second wall (12). The thickness of the second wall (12) is D2. The melting point of the material of the second wall (12) is T2. The energy density of the battery cell is E. The ratio of the product of the square of T2 and D2 to E is greater than or equal to 400.

14. The battery cell according to claim 13, characterized in that, The ratio of the product of the square of T2 and the product of D2 to E is greater than or equal to 600.

15. The battery cell according to claim 13 or 14, characterized in that, The T2 is greater than or equal to 600℃ and less than or equal to 1700℃; the D2 is greater than or equal to 0.15 mm and less than or equal to 2 mm; the E is greater than or equal to 700 Wh / L.

16. A battery, characterized in that, Includes the battery cell according to any one of claims 1 to 15.

17. An electrical device, characterized in that, Includes the battery according to claim 16.

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