Battery cell, battery pack, and electric device

Abstract

The application relates to the technical field of batteries, in particular to a battery cell, a battery pack and a power utilization device. The provided battery cell comprises a shell, a cover plate and an explosion-proof valve; the shell comprises a base material; the cover plate is arranged at an open end of the shell; the explosion-proof valve is arranged on the cover plate; in the thickness direction of the explosion-proof valve, one side of the explosion-proof valve is provided with a notch, and one side of the notch is surrounded to form an opening surface; in the thickness direction of the cover plate, the projection area of the cover plate away from the shell is S2; in the thickness direction of the explosion-proof valve, the projection area of the opening surface is S0; in the length direction of the shell, a welding convex part is arranged on the base material; in the width direction of the shell, heat-affected zones are arranged on the base material on both sides of the welding convex part, and the structural tensile strength of the heat-affected zones is R; wherein S0, S2 and R satisfy: 15MPa <= S0 / S2 x R <= 25MPa. The battery cell can timely discharge high-temperature and high-pressure gas generated during thermal runaway, and cracking will not occur in the heat-affected zone of the welding seam.

Description

TECHNICAL FIELD

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

[0002] When the battery cell is in thermal runaway, if the high-temperature and high-pressure gas generated is not discharged in time, the shell of the battery cell may be cracked, causing a safety risk. Therefore, how to improve the efficient and timely discharge performance of the battery cell becomes increasingly important. SUMMARY

[0003] Therefore, the present application aims to at least partially solve one of the problems in the related art. To this end, the present application provides a battery cell, a battery pack and an electric device, which can discharge the high-temperature and high-pressure gas generated during thermal runaway outside the shell in time, and the shell has sufficient structural strength and will not be cracked in the heat-affected zone of the weld to cause the battery cell to catch fire and explode.

[0004] To solve the above technical problems, the present application is implemented as follows:

[0005] According to one aspect of the present application, the present application provides a battery cell, comprising:

[0006] a shell comprising a base material;

[0007] a cover plate arranged at an open end of the shell;

[0008] an explosion-proof valve arranged on the cover plate, one side of the explosion-proof valve being provided with a notch in the thickness direction of the explosion-proof valve, and the notch being surrounded by an opening surface on one side;

[0009] In the thickness direction of the cover plate, the projected area of the cover plate is S2; and in the thickness direction of the explosion-proof valve, the projected area of the opening surface is S0.

[0010] In the length direction of the shell, a welding protrusion is arranged on the base material; and in the width direction of the shell, a heat-affected zone is arranged on the base material on both sides of the welding protrusion, and the structural tensile strength of the heat-affected zone is R.

[0011] wherein the S0, S2 and R satisfy: 15MPa≤S0 / S2×R≤25MPa.

[0012] In some embodiments, the material tensile strength of the base material is Rm, and the Rm satisfies: 190Mpa≤Rm≤245Mpa.

[0013] In some embodiments, the R and Rm further satisfy: R=σRm, wherein 0.7≤σ≤0.95.

[0014] In some embodiments, the S0 satisfies: 170mm 2 ≤S0≤770mm 2 .

[0015] In some embodiments, the S2 satisfies: 1620mm 2 ≤S2≤8100mm 2 .

[0016] In some embodiments, in the height direction of the shell, the thickness of the welding protrusion is t2, and the thickness of the base material is t1, wherein 1.30≤t2 / t1≤1.68.

[0017] In some embodiments, the t1 further satisfies: 0.25mm≤t1≤0.6mm.

[0018] In some embodiments, the t2 further satisfies: 0.4mm≤t2≤0.8mm.

[0019] In some embodiments, in the width direction of the shell, the width of the welding protrusion is w, wherein 1.0mm 2 ≤t2×w≤3.2mm 2 .

[0020] In some embodiments, the w further satisfies: 2mm≤w≤4mm.

[0021] In some embodiments, the welding protrusion is formed by welding, and in the welding process, the power of the welding is 10kW~12kW, and the speed of the welding is 40m / min~50m / min.

[0022] According to another aspect of the present application, the present application provides a battery pack, comprising: the battery cell according to any one of the embodiments of the first aspect of the present application.

[0023] According to a third aspect of the present application, the present application provides a power utilization device, comprising: the battery cell according to any one of the embodiments of the first aspect of the present application; and / or, the battery pack according to any one of the embodiments of the second aspect of the present application.

[0024] The technical solutions of the present application have at least the following beneficial effects:

[0025] In the present application, by limiting the ratio S0 / S2xR of the projection area of the cover plate and the opening surface and the tensile strength of the heat affected zone structure in the thickness direction of the cover plate, the high temperature and high pressure gas generated during thermal runaway can be discharged outside the shell in time, and the structural strength of the shell is sufficient, and rupture will not occur in the weld heat affected zone to cause the battery to catch fire and explode.

[0026] Additional aspects and advantages of the present application will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0028] Figure 1 A shell structure schematic diagram provided by the present application for the battery cell is shown.

[0029] Figure 2 A shell side view structure schematic diagram provided by the present application for the battery cell is shown.

[0030] Figure 3 A shell side view structure schematic diagram provided by the present application for the battery cell is shown. Figure 2 A partial enlarged structure schematic diagram of the middle shell is shown.

[0031] Figure 4 A shell structure schematic diagram provided by the present application for the battery cell is shown.

[0032] Figure 5 A shell structure schematic diagram provided by the present application for the battery cell is shown.

[0033] Figure 6 A shell structure schematic diagram provided by the present application for the battery cell is shown.

[0034] BRIEF DESCRIPTION OF DRAWINGS

[0035] 10 - battery cell:

[0036] 100 - shell; 110 - base material; 120 - welded protrusion; 130 - heat affected zone;

[0037] 200 - cover plate; 300 - pole; 400 - pole group;

[0038] 500 - explosion-proof valve; 510 - notch; 520 - opening surface; 530 - transition; 540 - skirt.

[0039] The specific embodiments of the present application have been shown and described in the above drawings and text. These drawings and text are not meant to limit the scope of the inventive concept in any way but are meant to illustrate the inventive concept to one of ordinary skill in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0040] The present application will be further illustrated by the following specific examples. It should be understood that these examples are intended to illustrate the present application and are not meant to limit the scope of the present application.

[0041] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges or values should be construed to be roughly about the ranges or values. The endpoints of the ranges of values stated as being the approximate values, and should be considered to include the precision of the endpoint and the precision of the various instruments used to determine the ranges or values.

[0042] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, if not specifically stated.

[0043] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, if not specifically stated.

[0044] All steps of the present application can be performed in sequence or randomly, preferably in sequence, if not specifically stated. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0045] If not specifically stated, "including" and "containing" mentioned in the present application means open-ended, and can also be closed. For example, "including" and "containing" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0046] Tensile strength of material: refers to the maximum stress value that the material can withstand when subjected to tensile load. It is an important mechanical property index to measure the material's resistance to tensile failure, usually expressed in megapascal (MPa) or other stress units. The tensile strength of the material is generally measured by experiment, for example, in the tensile test, the sample is clamped on the testing machine and subjected to tension until the sample breaks. In this process, the stress-strain curve can be drawn, and the following key parameters can be obtained: yield strength, ultimate tensile strength (UTS, Ultimate Tensile Strength) and fracture strength, etc.

[0047] When the battery cell experiences thermal runaway, a large amount of high-temperature and high-pressure gas will be generated inside the battery cell. The explosion-proof valve on the battery cell needs to be opened in time to discharge the gas and avoid the risk of cracking of the battery cell shell and side spraying. How to make the gas generation rate and the amount of gas generated during thermal runaway compatible with the exhaust rate and exhaust amount of the explosion-proof valve, and not cause the gas to be trapped, has become an important research topic.

[0048] In view of the problems existing in the prior art, the present application provides a battery cell, a battery pack and an electric device, which can well discharge the high-temperature and high-pressure gas generated during thermal runaway outside the shell in time, and the shell has sufficient structural strength and will not crack in the heat affected zone of the weld to cause the battery cell to catch fire and explode.

[0049] The technical scheme of the present application is as follows:

[0050] In some embodiments of the present application, a battery cell is provided, comprising: a shell 100, a cover plate 200 and an explosion-proof valve 500; the shell 100 comprises a base material 110; the cover plate 200 is arranged at the open end of the shell 100; the explosion-proof valve 500 is arranged on the cover plate 200, and one side of the explosion-proof valve 500 is provided with a notch 510 in the thickness direction of the explosion-proof valve 500, and the notch 510 is surrounded by an opening face 520.

[0051] Reference Figures 1 to 5The shell 100 is made of aluminum foil, copper foil or aluminum alloy, etc. A containing space is arranged in the shell 100 for mounting the pole group 400, the tab and the connecting sheet, etc. The cover plate 200 is arranged at the open end of the shell 100, and the cover plate 200 and the shell 100 can be connected by welding or bonding, etc. Of course, those skilled in the art can understand that the two sides of the cover plate 200 can be respectively provided with plastic pads in the thickness direction of the cover plate 200, and the plastic pads can be made of rubber, polyolefin or other insulating materials. The cover plate 200 can also be provided with a through hole, and the through hole can be provided with an explosion-proof valve 500 or a pole 300. In the thickness direction of the explosion-proof valve 500, a notch 510 is arranged on the end face of the explosion-proof valve 500. It can be understood that the notch 510 can be arranged on the side close to the pole group 400, or on the side away from the pole group 400. One side of the notch 510 is surrounded to form an opening face 520, that is, the notch 510 forms a closed shape, which can be rectangular, annular, circular or elliptical or other arbitrary shape. The other side of the notch 510 is surrounded by a transition part 530, and the periphery of the transition part 530 is surrounded by a skirt 540. It can also be understood that in the thickness direction of the explosion-proof valve 500, the thickness of the notch 510 is less than the thickness of the opening face 520. In this way, the explosion-proof valve 500 can be more easily and effectively opened for exhaust and pressure relief from the notch 510.

[0052] In some embodiments, in the thickness direction of the cover plate 200, the projected area of the cover plate 200 is S2; in the thickness direction of the explosion-proof valve 500, the projected area of the opening face 520 is S0; in the length direction of the shell 100, the base material 110 is provided with a welding convex part 120; in the width direction of the shell 100, the base material 110 on both sides of the welding convex part 120 is respectively provided with a heat affected zone 130, and the structural tensile strength of the heat affected zone 130 is R; wherein S0, S2 and R satisfy: 15MPa≤S0 / S2×R≤25MPa.

[0053] As an example, the ratio of S0 / S2×R can be any one of 15MPa, 15.5MPa, 16MPa, 17MPa, 18MPa, 19MPa, 20MPa, 21MPa, 22MPa, 23MPa, 24MPa or 25MPa, or any point value between any two of them. It can be understood that, as Figure 1As shown, when the cover plate 200 is arranged on the shell 100, the explosion-proof valve 500 is arranged on the cover plate 200 to assemble the battery cell 10, the length direction of the shell 100 is the thickness direction of the cover plate 200, and the thickness direction of the explosion-proof valve 500 is also the length direction of the battery cell 10. By limiting the range of the projection area of the opening surface 520 and the projection area of the cover plate 200 and the structural tensile strength of the heat-affected zone 130, the high-temperature gas generated during thermal runaway of the battery cell 10 can be quickly discharged in time, thereby improving the safety performance of the battery cell. The structural tensile strength refers to the ability of a material or component to resist damage when subjected to tensile load. It is one of the important indicators for measuring the mechanical properties of materials, and is usually expressed as the maximum tensile stress per unit area (unit: MPa). If the above ratio is not within the range, the gas generated during thermal runaway may not be discharged in time, resulting in a gas retention phenomenon. The structural strength of the heat-affected zone 130 of the shell 100 cannot effectively resist the pressure strength of the battery cell during gas retention, thereby causing cracking and side spraying, which poses a safety risk.

[0054] The battery cell provided by the application can quickly discharge the high-temperature and high-pressure gas generated during thermal runaway outside the shell, and the structural strength of the shell is sufficient to prevent cracking in the weld heat-affected zone and cause the battery cell to catch fire or explode.

[0055] In some embodiments, the material tensile strength of the base material 110 is Rm, and Rm satisfies: 190Mpa≤Rm≤245Mpa.

[0056] It can be understood that the material tensile strength Rm of the base material 110 can be any one of 190Mpa, 200Mpa, 210Mpa, 220Mpa, 230Mpa or 245Mpa, or any point value between any two of them. By limiting the material tensile strength of the base material 110, the shell 100 can have good structural strength and improve the safety performance of the battery cell.

[0057] In some embodiments, R and Rm also satisfy: R=σRm, where 0.7≤σ≤0.95.

[0058] It can be understood that, as an example, sigma can be any one of 0.7, 0.72, 0.75, 0.8, 0.85, 0.9 or 0.95, or any point value between any two of them. By limiting the range of the structural tensile strength, the heat-affected zone 130 can have good structural strength, and cracking of the heat-affected zone during thermal runaway can be avoided. In addition, during welding, the influence of high temperature generated during welding on the heat-affected zone is reduced, thereby further improving the safety performance of the battery cell.

[0059] In some embodiments, S0 satisfies: 170mm 2 ≤ S0 ≤ 770mm 2 .

[0060] Those skilled in the art can understand that, in the thickness direction of the explosion-proof valve 500, the projected area S0 of the opening surface 520 can be any one or any two of 170mm 2 , 200mm 2 , 300mm 2 , 400mm 2 , 500mm 2 , 600mm 2 , 650mm 2 , 700mm 2 , 750mm 2 or 770mm 2 ; by limiting the projected area of the opening surface 520, the explosion-proof valve 500 can have good exhaust capacity and exhaust rate, so that the gas generated inside the battery cell can be discharged in time, and gas retention and cracking of the shell 100 can be avoided; if the projected area of the opening surface 520 is too small, the gas may not be discharged in time, causing gas retention; if the projected area of the opening surface 520 is too large, the raw materials may be wasted, and the explosion-proof valve 500 may not be effectively opened and exhausted.

[0061] In some embodiments, S2 satisfies: 1620mm 2 ≤ S2 ≤ 8100mm 2 .

[0062] Those skilled in the art can understand that the area S2 can be any one or any two of 1620mm 2 , 1700mm 2 , 1800mm 2 , 2000mm 2 , 3000mm 2 , 4000mm 2 , 5000mm 2 , 6000mm 2 , 7000mm 2 or 8100mm 2 ; similarly, the battery cell can have good structural strength to prevent the shell 100 from cracking; at the same time, the explosion-proof valve 500 can be effectively opened.

[0063] In some embodiments, in the height direction of the shell 100, the thickness of the welding protrusion 120 is t2, and the thickness of the base material 110 is t1, wherein 1.30 ≤ t2 / t1 ≤ 1.68.

[0064] Reference is made to Figure 2 and Figure 3 It can be understood that, as an example, the thickness of the welding protrusion 120 is t2, the thickness of the base material 110 is t1, the ratio of t2 and t1 can be any one of 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65 or 1.68 or any point value between any two of them; by limiting the ratio of t2 and t1, the shell 100 can have better rigidity and strength, and when the base material 110 is welded to form the shell 100, the thickness of the welding protrusion 120 cannot be too thick, which can cause the unevenness of the external shape of the shell 100, and further affect the installation of the battery cell; at the same time, the shell 100 is not easy to break, when the thermal runaway occurs inside the battery cell, the shell 100 can resist the pressure inside the battery cell, so that the explosion-proof valve 500 opens to release pressure, so that the battery cell will not explode and cause dangerous events. If the above ratio is less than the range, the welding parameters may not be suitable, the welding power is too high or the welding speed is too slow, so that the temperature at the position of the welding protrusion 120 is too high, and the high temperature has too great an impact on the welding protrusion 120 and the heat affected zone 130, which can cause the explosion-proof valve 500 of the battery cell not to open, and the welding protrusion 120 or the heat affected zone 130 of the shell 100 to break. If the above ratio is greater than the range, the thickness of the base material 110 is thinner, which can make the rigidity or strength of the shell 100 not enough, and when a collision occurs, the shell 100 can be damaged or deformed, which can damage the pole group 400 inside the battery cell or the tabs on the pole group 400, affecting the normal work of the battery cell.

[0065] In some embodiments, t1 also satisfies: 0.25mm≤t1≤0.6mm.

[0066] Reference is made to Figure 2 and Figure 3 It can be understood that, as an example, the value range of t1 can be any one of 0.25mm, 0.3mm, 0.4mm, 0.5mm or 0.6mm or any point value between any two of them; by limiting the thickness range of the base material 110, the shell 100 can have good structural strength, further reducing the impact of temperature on the base material 110 during welding, ensuring that the shell 100 is not easy to crack, and the battery cell has good safety; if it is less than the above range, the structural strength of the shell 100 will be reduced, the heat affected zone 130 of the shell 100 is easy to crack, and when the battery cell collides, the shell 100 can be deformed, damaging the internal components and elements of the battery cell; if it is greater than the above range, it can cause waste of raw materials, and further increase the cost.

[0067] In some embodiments, t2 also satisfies: 0.4mm≤t2≤0.8mm.

[0068] Reference is made to Figure 2 and Figure 3 It can be understood that, as an example, the value range of t2 can be any one of 0.4 mm, 0.45 mm, 0.5 mm, 0.6 mm, 0.7 mm or 0.8 mm or any point value between any two of them; by limiting the thickness of the welding protrusion 120, the overall structural strength of the shell 100 can be well controlled, the overall structural strength of the shell 100 is uniform, and the structure strength at a certain position is not weak, which is prone to cracking at this position, and at the same time, the shell 100 has a good appearance. If t2 is too large, the shell 100 will be uneven and not easy to install on other equipment.

[0069] In some embodiments, in the width direction of the shell 100, the width of the welding protrusion 120 is w, wherein 1.0 mm 2 ≤t2×w≤3.2 mm 2 .

[0070] It can be understood that, as an example, the width w of the welding protrusion 120 can be any one of 1.0 mm 2 , 1.1 mm 2 , 1.2 mm 2 , 1.3 mm 2 , 1.4 mm 2 , 1.5 mm 2 , 1.6 mm 2 , 1.7 mm 2 , 1.8 mm 2 , 1.9 mm 2 , 2.0 mm 2 , 2.2 mm 2 , 2.4 mm 2 , 2.6 mm 2 , 2.8 mm 2 , 3.0 mm 2 , 3.1 mm 2 , 3.15 mm 2 or 3.2 mm 2 or any point value between any two of them; by limiting the width of the welding protrusion 120, the base material 110 can be firmly connected, and at the same time, the influence of welding on the base material 110 can be ensured. As an example, the welding power and welding time can be controlled within a reasonable range, and thus the heat-affected zone 130 can have a good structural strength to avoid easy cracking of the heat-affected zone.

[0071] In some embodiments, w also satisfies: 2 mm≤w≤4 mm.

[0072] Reference is made to Figure 3It can be understood that, as an example, in the width direction of the shell 100, the width of the welding protrusion 120 can be any one of 2 mm, 2.5 mm, 3 mm or 4 mm or any point value between any two of them; by limiting the width of the welding protrusion 120, the use of the base material 110 can be maximized, the shell 100 with the largest space can be formed, and the relative edges of the base material 110 can be firmly welded. If the above width is too large, raw materials are wasted, and if it is too small, the welding protrusion 120 position is not firm after welding and is prone to cracking.

[0073] In some embodiments, the welding protrusion 120 is formed by welding, and in the welding process, the welding power is 10 kW-12 kW, and the welding rate is 40 m / min-50 m / min.

[0074] It can be understood that the welding protrusion 120 is formed by welding the base material 110, and in the welding process, the welding power can be 10 kW, 11 kW or 12 kW, and the welding rate can be any one of 40 m / min, 42 m / min, 45 m / min, 48 m / min or 50 m / min or any point value between any two of them; by limiting the welding power and the welding rate range, the base material 110 can form a shell 100 with excellent structural strength, so that the base material 110 grains in the welding area and the nearby area will not become coarse, affecting the structural strength of the shell 100, and thus reducing the safety performance of the battery cell.

[0075] In some embodiments of the present application, a battery pack is provided, comprising: the battery cell in any of the above embodiments.

[0076] In some embodiments of the present application, a battery pack is provided, comprising: the battery cell in any of the above embodiments.

[0077] In some embodiments, the electrical device includes the battery pack in any of the above embodiments.

[0078] Optionally, the battery cell can further include a positive electrode tab, a negative electrode tab and a separator. As an example, the positive electrode tab includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector in the thickness direction. The "positive electrode active material layer disposed on at least one surface of the positive electrode current collector" means that the positive electrode active material layer can be disposed on one surface of the positive electrode current collector in the thickness direction of the positive electrode current collector, or can be disposed on both surfaces of the positive electrode current collector in the thickness direction of the positive electrode current collector. The "surface" herein can be the entire area of the positive electrode current collector, or can be a partial area of the positive electrode current collector, and the present application is not particularly limited as long as the purpose of the present application can be achieved. In the present application, the separator is not particularly limited as long as the purpose of the present application can be achieved. Optionally, the separator includes, but is not limited to, a polymer separator of at least one of polyethylene, polypropylene, polyacrylonitrile, polysulfone, polyarylether sulfone, polyvinyl alcohol, and polyvinylidene fluoride.

[0079] As an example, the electric device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, an energy storage device, an amusement device, an elevator and a lifting device, etc. The electric toy includes a stationary or mobile electric toy, such as a game console, an electric car toy, an electric ship toy or an electric aircraft toy, etc. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator and an electric planer, etc. The energy storage device can be an energy storage wall, a base station energy storage, a container energy storage, etc. The amusement device can be a carousel, a free fall machine, etc. The vehicle can be a fuel automobile, a gas automobile or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile or a range extended automobile, etc. The vehicle is internally provided with a battery, which can be arranged at the bottom, the head or the tail of the vehicle. The battery can be used for power supply of the vehicle, for example, the battery can be used as an operating power source of the vehicle. The vehicle can further include a controller and a motor, and the controller is used to control the battery to supply power to the motor, for example, to meet the working power demand of the vehicle during starting, navigation and driving. The battery can not only be used as an operating power source of the vehicle, but also be used as a driving power source of the vehicle, to replace or partially replace fuel or natural gas to provide driving power for the vehicle.

[0080] Since the battery provided by the embodiment of the present application adopts all the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0081] The present application will be described in detail below in conjunction with the drawings and examples, but the implementation and protection of the present application are not limited thereto. The following embodiments are only part of the embodiments of the present application, and are not a limitation on the present application.

[0082] Embodiment 1

[0083] The parameters for the cell in Example 1 are: t1 = 0.25 mm, t2 = 0.42 mm, w = 2.5 mm, Rm = 195 MPa, σ = 0.75, R = 146.25 MPa, S2 = 1620 mm 2 S0 = 170 mm 2 t2 x w = 1.05 mm 2 t2 / t1 = 1.68, S0 / S2 x R = 15.35 MPa.

[0084] Example 2

[0085] The only difference between Example 2 is: t1 = 0.3 mm, t2 = 0.5 mm, w = 2 mm, Rm = 195 MPa, σ = 0.7, R = 136.5 MPa, S2 = 1890 mm 2 S0 = 209 mm 2 t2 x w = 1.00 mm 2 t2 / t1 = 1.67, S0 / S2 x R = 15.09 MPa.

[0086] Example 3

[0087] The only difference between Example 3 is: t1 = 0.35 mm, t2 = 0.55 mm, w = 2.2 mm, Rm = 195 MPa, σ = 0.7, R = 136.5 MPa, S2 = 2100 mm 2 S0 = 240 mm 2 t2 x w = 1.21 mm 2 t2 / t1 = 1.57, S0 / S2 x R = 15.60 MPa.

[0088] Example 4

[0089] The only difference between Example 4 is: t1 = 0.4 mm, t2 = 0.57 mm, w = 2.2 mm, Rm = 195 MPa, σ = 0.75, R = 146 MPa, S2 = 2500 mm 2 S0 = 299 mm 2 t2 x w = 1.25 mm 2 t2 / t1 = 1.43, S0 / S2 x R = 17.49 MPa.

[0090] Example 5

[0091] The only difference between Example 5 is: t1 = 0.45 mm, t2 = 0.58 mm, w = 2.5 mm, Rm = 210 MPa, σ = 0.75, R = 157.5 MPa, S2 = 3360 mm 2 S0 = 336 mm2 t2 x w = 1.45 mm 2 t2 / t1 = 1.29, S0 / S2 x R = 15.75 MPa.

[0092] Example 6

[0093] Example 6 differs only in that t1 = 0.5 mm, t2 = 0.58 mm, w = 2.5 mm, Rm = 210 MPa, σ = 0.75, R = 157.5 MPa, S2 = 3600 mm 2 S0 = 512 mm 2 t2 x w = 1.45 mm 2 t2 / t1 = 1.16, S0 / S2 x R = 22.40 MPa.

[0094] Example 7

[0095] Example 7 differs only in that t1 = 0.5 mm, t2 = 0.65 mm, w = 3 mm, Rm = 210 MPa, σ = 0.75, R = 157.5 MPa, S2 = 4320 mm 2 S0 = 560 mm 2 t2 x w = 1.95 mm 2 t2 / t1 = 1.30, S0 / S2 x R = 20.42 MPa.

[0096] Example 8

[0097] Example 8 differs only in that t1 = 0.55 mm, t2 = 0.66 mm, w = 3 mm, Rm = 210 MPa, σ = 0.8, R = 168 MPa, S2 = 4725 mm 2 S0 = 592 mm 2 t2 x w = 1.98 mm 2 t2 / t1 = 1.20, S0 / S2 x R = 21.05 MPa.

[0098] Example 9

[0099] Example 9 differs only in that t1 = 0.55 mm, t2 = 0.68 mm, w = 3.2 mm, Rm = 220 MPa, σ = 0.8, R = 176 MPa, S2 = 5250 mm 2 S0 = 576 mm 2 t2 x w = 2.18 mm 2 t2 / t1 = 1.24, S0 / S2 x R = 19.31 MPa.

[0100] Example 10

[0101] Example 10 differs only in that t1 = 0.55 mm, t2 = 0.7 mm, w = 3.2 mm, Rm = 220 MPa, σ = 0.85, R = 187 MPa, S2 = 5700 mm 2 , S0 = 684 mm 2 , t2 x w = 2.24 mm 2 , t2 / t1 = 1.27, S0 / S2 x R = 22.44 MPa.

[0102] Example 11

[0103] Example 11 differs only in that t1 = 0.6 mm, t2 = 0.8 mm, w = 4 mm, Rm = 245 MPa, σ = 0.95, R = 232 MPa, S2 = 6840 mm 2 , S0 = 741 mm 2 , t2 x w = 3.20 mm 2 , t2 / t1 = 1.33, S0 / S2 x R = 25.21 MPa.

[0104] Example 12

[0105] Example 12 differs only in that t1 = 0.6 mm, t2 = 0.78 mm, w = 4 mm, Rm = 220 MPa, σ = 0.95, R = 209 MPa, S2 = 8100 mm 2 , S0 = 770 mm 2 , t2 x w = 3.12 mm 2 , t2 / t1 = 1.30, S0 / S2 x R = 19.87 MPa.

[0106] Comparative Example 1

[0107] Comparative Example 1 differs only in that t1 = 0.3 mm, t2 = 0.42 mm, w = 2 mm, Rm = 195 MPa, σ = 0.75, R = 146 MPa, S2 = 1620 mm 2 , S0 = 150 mm 2 , t2 x w = 0.84 mm 2 , t2 / t1 = 1.40, S0 / S2 x R = 13.54 MPa.

[0108] Comparative Example 2

[0109] Comparative Example 2 differs only in that t1 = 0.45 mm, t2 = 0.58 mm, w = 2.5 mm, Rm = 210 MPa, σ = 0.75, R = 157.5 MPa, S2 = 3360 mm 2 , S0 = 300 mm 2 , t2 x w = 1.45 mm2 t2 / t1 = 1.29, S0 / S2 x R = 14.06 MPa.

[0110] Comparative Example 3

[0111] Comparative Example 3 differs only in that t1 = 0.55 mm, t2 = 0.59 mm, w = 3.2 mm, Rm = 190 MPa, σ = 0.7, R = 133 MPa, S2 = 5250 mm 2 S0 = 576 mm 2 t2 x w = 1.89 mm 2 t2 / t1 = 1.07, S0 / S2 x R = 15.59 MPa.

[0112] Performance test:

[0113] In order to verify the rationality of the explosion-proof valve area design, different sizes of DOE were arranged to verify the safety performance of the battery cell, and the results are shown in Table 1.

[0114] Table 1. Test results:

[0115]

[0116] It can be seen that when the explosion-proof valve area satisfies 15≤S0 / S2 x R≤25, the battery cell safety test is passed, the exhaust area meets the safety requirement of the battery cell, and there is no problem of tearing at the shell weld. On the contrary, when the exhaust area is insufficient, the explosion-proof valve does not open, the shell weld tears and catches fire, and the battery cell safety test fails.

[0117] The part of the present application not described in detail is the technology known to those skilled in the art.

[0118] The basic principles of the present application are described above in combination with specific embodiments, but it should be pointed out that the advantages, advantages, effects and the like mentioned in the present application are only examples and not limitations, and these advantages, advantages, effects and the like cannot be considered as the must-have of each embodiment of the present application. In addition, the above specific details are only for the purpose of example and for the purpose of understanding, and are not limited to the above specific details to realize the present application.

[0119] It should be noted that the term "and / or" or " / " used herein 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, which means that there are three cases of A alone, A and B together, and B alone. The singular form "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural form, unless the context clearly indicates otherwise.

[0120] In the DETAILED DESCRIPTION and in the claims, a list of items connected with the term "at least one of" can mean any combination of the items in the list. For example, if the list contains items A, B, and C, the phrase "at least one of A, B, and C" can mean A alone; B alone; C alone; A and B together; A and C together; B and C together; or A, B, and C together. The item A can include a single element or multiple elements. The item B can include a single element or multiple elements. The item C can include a single element or multiple elements.

[0121] Finally, it should be noted that the above embodiments are merely used to illustrate the technical solutions of the present application, rather than limit the present application; even though the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalent replacements; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, characterized in that, include: The housing, including the base material; A cover plate is provided at the open end of the housing; An explosion-proof valve is provided on the cover plate. In the thickness direction of the explosion-proof valve, one side of the explosion-proof valve is provided with a groove, and one side of the groove forms an opening surface. In the thickness direction of the cover plate, the projected area of ​​the cover plate is S2; in the thickness direction of the explosion-proof valve, the projected area of ​​the opening surface is S0. Along the length of the housing, a welding protrusion is provided on the substrate; along the width of the housing, heat-affected zones are respectively provided on the substrate located on both sides of the welding protrusion, and the tensile strength of the heat-affected zones is R. S0, S2 and R satisfy: 15MPa≤(S0 / S2)×R≤25MPa; The tensile strength of the substrate is Rm, which satisfies: 190MPa≤Rm≤245MPa; R and Rm also satisfy: R=σRm, where 0.7≤σ≤0.95; The S0 satisfies: 170mm 2 ≤S0≤770mm 2 The S2 satisfies: 1620mm 2 ≤S2≤8100mm 2 ; In the height direction of the housing, the thickness of the welding protrusion is t2, and the thickness of the substrate is t1, wherein 1.30≤t2 / t1≤1.68; 0.25mm≤t1≤0.6mm; 0.4mm≤t2≤0.8mm; In the width direction of the housing, the width of the welded protrusion is w, where 1.0 mm 2 ≤t2×w≤3.2mm 2 ;2mm≤w≤4mm; Wherein, the length direction of the housing is the thickness direction of the cover plate, the thickness direction of the explosion-proof valve, and the length direction of the battery cell.

2. The battery cell according to claim 1, characterized in that, The welding protrusion is formed by welding. During the welding process, the welding power is 10kW~12kW and the welding speed is 40m / min~50m / min.

3. A battery pack, characterized in that, include: The battery cell according to claim 1 or 2.

4. An electrical appliance, characterized in that, include: The battery cell according to claim 1 or 2; Alternatively, the battery pack as described in claim 3.

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