Battery cell and battery pack

Abstract

The application relates to the technical field of batteries, in particular to a battery cell and a battery pack. The disclosed battery cell comprises a shell and a cover plate; the shell comprises a base material; the cover plate is arranged at the open end of the shell; a welding convex part is arranged on the base material in the length direction of the shell; heat affected zones are respectively arranged on the base materials on the two sides of the welding convex part in the width direction of the shell; the average grain size of the base material is A2, the average grain size of the heat affected zone material is A1, and A1 and A2 satisfy 1.0 <= A1 / A2 <= 1.5. The battery cell can well control the influence of welding temperature on the base material during the welding process, the shell has good structural strength and is not prone to cracking and damage, and the safety performance of the battery cell is effectively improved.

Description

TECHNICAL FIELD

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

[0002] The strength, thickness and other parameters of the shell in the battery have an important influence on whether the explosion-proof valve can be normally opened to release pressure. If the parameters of the explosion-proof valve and the shell are not reasonably designed, the explosion-proof valve may not be normally opened or the shell may be broken. SUMMARY

[0003] Therefore, the present application aims to at least solve one of the technical problems in the related art. To this end, the present application provides a battery cell and a battery pack, which can well control the influence of welding temperature on the base material during welding, so that the shell has good structural strength and is not easy to crack or break, thereby effectively improving the safety performance of the battery cell.

[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] In the length direction of the shell, a welding protrusion is arranged on the base material; in the width direction of the shell, a heat-affected zone is arranged on the base material on both sides of the welding protrusion, respectively;

[0009] The average grain size of the base material is A2, the average grain size of the heat-affected zone material is A1, and the A1 and A2 satisfy: 1.0≤A1 / A2≤1.5.

[0010] In some embodiments, an explosion-proof valve is further included;

[0011] The explosion-proof valve is arranged on the cover plate, an end surface of the explosion-proof valve is provided with a notch, and one side of the notch is surrounded to form an opening surface;

[0012] In the thickness direction of the cover plate, the projection area of the cover plate is S2; in the thickness direction of the explosion-proof valve, the projection area of the opening surface is S0;

[0013] Wherein, the S0 and S1 satisfy: 5≤(100*S0 / S2) / (A1 / A2)≤15.

[0014] In some embodiments, the thickness of the welding protrusion is t2, the thickness of the base material is t1, and t1 and t2 satisfy 1.1≤t2 / t1≤2.0 in the height direction of the shell.

[0015] In some embodiments, t1 is in the range of 0.25mm≤t1≤0.6mm.

[0016] In some embodiments, t2 is in the range of 0.4mm≤t2≤0.8mm.

[0017] In some embodiments, the width of the welding protrusion is 2mm~4mm in the width direction of the shell.

[0018] In some embodiments, the width of the heat-affected zone on either side of the welding protrusion is 1mm~2mm in the width direction of the shell.

[0019] In some embodiments, the tensile strength of the base material is Rm, and 190Mpa≤Rm≤245Mpa.

[0020] In some embodiments, the welding protrusion is formed by welding the base material, and the welding power is 10kW~12kW and the welding rate is 40m / min~50m / min during the welding process.

[0021] In some embodiments, the battery pack further comprises a pole and a pole group.

[0022] The pole is arranged on the cover plate, and the pole group is arranged in the shell.

[0023] According to the second aspect of the present application, the present application further provides a battery pack comprising the battery cell according to any one of the embodiments of the first aspect of the present application.

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

[0025] 1、In the present application, by limiting the ratio range of the average grain size of the base material and the heat-affected zone on the shell, the influence of the welding temperature on the base material during the welding process can be well controlled, the shell has good structural strength and is not easy to crack or break, and the safety performance of the battery cell is effectively improved.

[0026] 2. In the preferred embodiment of the present application, by setting the area of the design opening surface, the area of the cover plate, and the ratio of the average grain size of the base material and the heat-affected zone within a certain range, the safety performance of the battery cell can be improved, the heat-affected zone has good structural strength, and the opening surface can be normally opened to discharge and release pressure, and the shell will not crack.

[0027] Additional aspects and advantages of the present application will be partially given in the following description, partially will become apparent from the following description, or will be understood by those skilled in the art through the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0028] The drawings incorporated into the specification and forming part of the specification, show embodiments consistent with the present application, and together with the specification, serve to explain the principles of the present application.

[0029] Figure 1 The shell structure schematic diagram provided by the present application is shown.

[0030] Figure 2 The shell side view structure schematic diagram provided by the present application is shown.

[0031] Figure 3 The shell structure schematic diagram provided by the present application is shown. Figure 2 The partial enlarged structure schematic diagram of the middle shell is shown.

[0032] Figure 4 The shell plane structure schematic diagram provided by the present application is shown.

[0033] Figure 5 The metallographic map of the welding convex part and the heat-affected zone of the shell base material provided by the present application is shown.

[0034] Figure 6 The enlarged map of the welding convex part of the shell base material provided by the present application is shown.

[0035] Figure 7 The explosion-proof valve structure schematic diagram of the battery cell provided by the present application is shown.

[0036] Figure 8 The battery cell structure schematic diagram provided by the present application is shown.

[0037] BRIEF DESCRIPTION OF DRAWINGS

[0038] 10 - battery cell:

[0039] 100 - shell; 110 - base material; 120 - welding convex part; 130 - heat-affected zone;

[0040] 200 - cover plate; 300 - pole; 400 - pole group;

[0041] 500 - rupture disc; 510 - score; 520 - opening face; 530 - transition; 540 - skirt.

[0042] The specific embodiments of the present application have been shown and described in the above-described drawings and specification, it is to be understood that the scope of the present application is not to be limited by any of the specific embodiments described or shown, but only by the scope of the appended claims. Various modifications within the scope of the present application will be readily apparent to those of ordinary skill in the art, and the scope of the present application should in no way be limited only by the description and figures above. DETAILED DESCRIPTION

[0043] The technical solutions of the present application and how the technical solutions solve the above technical problems will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described again in some embodiments. The embodiments of the present application will be described below with reference to the drawings.

[0044] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The endpoints of the ranges and any values should be understood to be approximate. The exact values will depend on the particular context or the particular embodiment. The ranges and values are approximations that are already "as close as practicable". Any numerical value, however, can be expressed within a range by either adding or subtracting a number that is approximately 10% of, or close to, the value. For example, a value can be expressed as follows: 1 to 2, or 1.0 ± 10%, or, more particularly, 1.0 ± 0.1, or 1 to 1.1, or 0.9 to 2, or 0.9 to 1.1, etc. Any numerical value, however, can be expressed within a range by either adding or subtracting a number that is approximately 10% of, or close to, the value. For example, a value can be expressed as follows: 1 to 2, or 1.0 ± 10%, or, more particularly, 1.0 ± 0.1, or 1 to 1.1, or 0.9 to 2, or 0.9 to 1.1, etc.

[0045] If not specifically explained, all the embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0046] If not specifically explained, all the technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0047] First, the terms appearing in the present application are explained:

[0048] Grain size: refers to the size of a single grain in a product body. The classification of grain size is often determined according to the structure type and material composition of the product body, for example, the grain size distribution of metal materials and ceramic materials may be completely different. In engineering applications, the control of grain size is crucial to improve the strength, toughness and corrosion resistance of materials.

[0049] Average grain size, the following methods can be used:

[0050] Scherrer formula: D = Kλ / (βcosθ), where K is a constant, λ is the X-ray wavelength, β is the half-height width of the diffraction peak, and θ is the diffraction angle.

[0051] Intercept method: the average intercept length of a grain is calculated by intercepting the grain with a straight line of a certain length. Let the length of the straight line be L and the total number of intercepted grains be N, then the average grain size is L / N.

[0052] Jade software: the average grain size is calculated by the half-height width of the diffraction peak using the Scherrer formula.

[0053] The shell is usually formed by winding and bending a metal foil and then welding. During the welding process, a welding area is formed on the metal foil. The metal foil near the welding area is affected by the welding heat, which changes the rigidity, strength or metal grain of the area. When the cover plate is installed on the shell to form a closed space, if thermal runaway occurs inside the battery, the explosion-proof valve on the cover plate can open to release pressure. However, if the welding process has a large impact on the metal foil near the welding area and the size of the explosion-proof valve is not reasonable, the explosion-proof valve may not open normally and the shell may crack.

[0054] In view of the technical problems existing in the prior art, the present application provides an electric core and a battery pack, which can well control the influence of welding temperature on the base material during the welding process, so that the shell has good structural strength and is not easy to crack or break, effectively improving the safety performance of the electric core.

[0055] In some embodiments of the present application, an electric core is provided, comprising: a shell 100 and a cover plate 200; the shell 100 comprises a base material 110; the cover plate 200 is arranged at the open end of the shell 100; in the length direction of the shell 100, a welding protrusion 120 is arranged on the base material 110; in the width direction of the shell 100, a heat affected zone 130 is arranged on the base material 110 on both sides of the welding protrusion 120; the average grain size of the base material 110 is A2, the average grain size of the heat affected zone 130 is A1, and A1 and A2 satisfy: 1.0≤A1 / A2≤1.5.

[0056] Reference Figure 1 The shell 100 is made of an aluminum foil, a copper foil or an aluminum alloy base material 110. Exemplarily, the base material 110 can be a rectangular aluminum alloy sheet. The two opposite edges of the rectangular base material 110 are connected together by winding and bending, and a welding protrusion 120 is formed on the base material 110 in the length direction of the shell 100. The cover plate 200 is made of an aluminum foil, a copper foil or an aluminum alloy metal material. The cover plate 200 is arranged at the open end of the shell 100. It can be understood that the two sides of the cover plate 200 are provided with upper and lower plastic parts made of insulating material, as well as sealing members, which are not limited in the present application. The shell 100 and the cover plate 200 form a containing space, and a pole group 400 can be arranged in the containing space.

[0057] ReferenceFigure 2 and Figure 3 The welding protrusion 120 is formed on the welding substrate 110. Since the metal substrate 110 has a thermal conductivity effect, heat-affected zones 130 are formed on the substrate 110 on both sides of the welding protrusion 120 in the width direction of the housing 100. For example,... Figure 5 As shown in the metallographic diagram, the central part is the weld protrusion 120, and the two sides are heat-affected zones 130. During the formation of the weld protrusion 120 from the weld substrate 110, the high temperature generated during welding significantly affects the substrate 110 near both sides of the weld protrusion 120, forming the heat-affected zones 130. The higher temperature affects the grain size of the metal, causing grain regrowth or recrystallization. Therefore, when designing and manufacturing the shell 100, the average grain size of the substrate 110 is A2, and the average grain size of the heat-affected zone 130 is A1. The ratio of A1 to A2 can be one of 1.0, 1.05, 1.1, 1.14, 1.2, 1.3, 1.4, or 1.5. Any value between or between any two of these factors; by limiting the range of the ratio of the average grain size of the substrate 110 and the heat-affected zone 130, it is possible to ensure that the shell 100 has a certain strength, and that the structural strength of the weld protrusion 120 and the heat-affected zone 130 of the shell 100 is not too low. Therefore, when thermal runaway occurs inside the cell, the heat-affected zone 130 of the shell 100 will not crack, leading to safety problems such as electrode side spraying, fire, and explosion. This allows the explosion-proof valve 500 on the cell to be supported and opened for venting and depressurization. This can better ensure that the cell has high safety performance. If the ratio of A1 and A2 is greater than the above range, it indicates that when the weld protrusion 120 is formed, the high temperature generated by welding has a greater impact on the heat-affected zone 130, resulting in coarser grains in the heat-affected zone 130, which reduces the structural strength of the heat-affected zone 130. This may cause the explosion-proof valve 500 to fail to open properly when the cell experiences thermal runaway, and the shell 100 of the heat-affected zone 130 to crack, which could easily lead to a safety accident. If the ratio of A1 to A2 is less than the above range, that is, the average grain size of the substrate 110 is larger, it is likely to reduce the overall structural strength of the casing 100. In addition to the casing 100 being prone to cracking due to thermal runaway of the battery cell, the casing 100 is also prone to damage or deformation when the battery cell is impacted, which may in turn damage the electrode group 400 and other components inside the battery cell.

[0058] The battery cell provided by this invention, by limiting the range of the ratio of the average grain size of the substrate and the heat-affected zone on the casing, can effectively control the influence of welding temperature on the substrate during the welding process, so that the casing has good structural strength and is not prone to cracking or damage, thus effectively improving the safety performance of the battery cell.

[0059] In some embodiments, the explosion-proof valve 500 is further included; the explosion-proof valve 500 is arranged on the cover plate 200, and a notch 510 is arranged on an end face of the explosion-proof valve 500; one side of the notch 510 is surrounded to form an opening face 520; in a thickness direction of the cover plate 200, a projection area of the cover plate 200 is S2; in a thickness direction of the explosion-proof valve 500, a projection area of the opening face 520 is S0; wherein S0 and S1 satisfy: 5≤(100*S0 / S2) / (A1 / A2)≤15.

[0060] With reference to Figure 7 and Figure 8 , the explosion-proof valve 500 is arranged on the cover plate 200, and a notch 510 is arranged on an end face of the explosion-proof valve 500; one side of the notch 510 is surrounded to form an opening face 520; in a thickness direction of the cover plate 200, a projection area of the cover plate 200 is S2; in a thickness direction of the explosion-proof valve 500, a projection area of the opening face 520 is S0; wherein S0 and S1 satisfy: 5≤(100*S0 / S2) / (A1 / A2)≤15.

[0061] In some embodiments, in a height direction of the shell 100, the thickness of the welding convex part 120 is t2, and the thickness of the base material 110 is t1; t1 and t2 satisfy: 1.1≤t2 / t1≤2.0.

[0062] With reference to Figure 2 and Figure 3As an example, in the height direction of the shell 100, the thickness of the welding convex portion 120 is t2, and the thickness of the base material 110 is t1, the ratio of t2 and t1 can be any one of 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2.0 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 convex portion 120 will not be too thick, which will cause the unevenness of the external shape of the shell 100, and then 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, which will cause the temperature at the position of the welding convex portion 120 to be too high, and then the high temperature will have too much influence on the welding convex portion 120 and the heat affected zone 130, which may cause the explosion-proof valve 500 of the battery cell not to open, and the welding convex portion 120 or the heat affected zone 130 of the shell 100 to break.

[0063] In some embodiments, t1 can be in the range of 0.25mm≤t1≤0.6mm.

[0064] Reference Figure 2 and Figure 3 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 reduce the influence of temperature on the base material 110 during welding, and ensure that the shell 100 is not easy to crack, so that 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, it may cause the shell 100 to deform and damage the internal components and elements of the battery cell; if it is greater than the above range, it may cause waste of raw materials, and then increase the cost.

[0065] In some embodiments, t2 can be in the range of 0.4mm≤t2≤0.8mm.

[0066] Reference Figure 2 and Figure 3The value 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 structural strength of a certain position is not weak, which is prone to cracking at this position. At the same time, the shell 100 also has a good appearance. If t2 is too large, the shell 100 will be uneven and difficult to install on other equipment.

[0067] In some embodiments, in the width direction of the shell 100, the width of the welding protrusion 120 is 2 mm to 4 mm.

[0068] Reference Figure 3 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 to form a shell 100 with maximum space, and the opposite 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.

[0069] In some embodiments, in the width direction of the shell 100, the width of the heat-affected zone 130 on either side of the welding protrusion 120 is 1 mm to 2 mm.

[0070] Reference Figure 3 In the width direction of the shell 100, the width of the heat-affected zone 130 on either side of the welding protrusion 120 can be any one of 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.8 mm or 2 mm or any point value between any two of them. By limiting the width of the heat-affected zone 130, the welding power, time, etc. during welding can be well guaranteed, thereby minimizing the influence of welding temperature, making the grain size between the heat-affected zone 130 and the base material 110 relatively small, and the shell 100 has good structural strength and is not prone to cracking.

[0071] In some embodiments, the tensile strength of the base material 110 is Rm, wherein 190 Mpa≤Rm≤245 Mpa.

[0072] It can be understood that the tensile strength Rm of the material of the substrate 110 can be any one of 190 Mpa, 200 Mpa, 210 Mpa, 220 Mpa, 230 Mpa or 245 Mpa, or any point value between any two of them; by limiting the material tensile strength of the substrate 110, the shell 100 can have good structural strength, and the safety performance of the battery cell can be improved.

[0073] In some embodiments, the welding convex part 120 is formed by welding the substrate 110, and the welding power is 10kW~12kW and the welding speed is 40m / min~50m / min during the welding process.

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

[0075] In some embodiments, the battery cell further comprises a pole 300 and a pole group 400; the pole 300 is arranged on the cover plate 200, and the pole group 400 is arranged in the shell 100.

[0076] Reference Figure 8 The battery cell further comprises a pole 300, the pole 300 can pass from one side of the cover plate 200 to the other side and be connected to the cover plate 200, and the pole group 400 can be provided with a tab, one end of the tab being connected to the pole 300, so as to realize the charging and discharging of the battery cell.

[0077] In some embodiments of the present application, a battery pack is also provided, which comprises the battery cell in any of the above embodiments.

[0078] Since the battery provided by the embodiments 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.

[0079] 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, and the following embodiments are only part of the embodiments of the present application, not a limitation of the present application.

[0080] Embodiment 1

[0081] In Example 1, the various parameters for the cell are t1 = 0.25 mm, t2 = 0.42 mm, t2 / t1 = 1.68, S0 = 170 mm 2 , S2 = 1620 mm 2 , 100*S0 / S2 = 10.49, A1 = 0.02 mm, A2 = 0.016 mm, A1 / A2 = 1.25, (100*S0 / S2) / (A1 / A2) = 8.40.

[0082] Example 2

[0083] Example 2 differs only in that t1 = 0.3 mm, t2 = 0.5 mm, t2 / t1 = 1.67, S0 = 209 mm 2 , S2 = 1890 mm 2 , 100*S0 / S2 = 11.06, A1 = 0.019 mm, A2 = 0.017 mm, A1 / A2 = 1.12, (100*S0 / S2) / (A1 / A2) = 9.89.

[0084] Example 3

[0085] Example 3 differs only in that t1 = 0.35 mm, t2 = 0.55 mm, t2 / t1 = 1.57, S0 = 240 mm 2 , S2 = 2100 mm 2 , 100*S0 / S2 = 11.43, A1 = 0.02 mm, A2 = 0.016 mm, A1 / A2 = 1.25, (100*S0 / S2) / (A1 / A2) = 9.14.

[0086] Example 4

[0087] Example 4 differs only in that t1 = 0.4 mm, t2 = 0.57 mm, t2 / t1 = 1.43, S0 = 299 mm 2 , S2 = 2500 mm 2 , 100*S0 / S2 = 11.96, A1 = 0.021 mm, A2 = 0.018 mm, A1 / A2 = 1.17, (100*S0 / S2) / (A1 / A2) = 10.25.

[0088] Example 5

[0089] Example 5 differs only in that t1 = 0.45 mm, t2 = 0.58 mm, t2 / t1 = 1.29, S0 = 336 mm 2 , S2 = 3360 mm 2, 100*S0 / S2=10.00, A1=0.02mm, A2=0.015mm, A1 / A2=1.33, (100*S0 / S2) / (A1 / A2)=7.50.

[0090] Example 6

[0091] The only difference in Example 6 is that t1=0.5mm, t2=0.58mm, t2 / t1=1.16, and S0=512mm. 2 S2=3600mm 2 , 100*S0 / S2=14.22, A1=0.025mm, A2=0.020mm, A1 / A2=1.25, (100*S0 / S2) / (A1 / A2)=11.38.

[0092] Example 7

[0093] The only difference in Example 7 is that t1=0.5mm, t2=0.65mm, t2 / t1=1.30, and S0=560mm. 2 S2 = 4320mm 2 , 100*S0 / S2=12.96, A1=0.022mm, A2=0.018mm, A1 / A2=1.22, (100*S0 / S2) / (A1 / A2)=10.61.

[0094] Example 8

[0095] The only difference in Example 8 is that t1=0.55mm, t2=0.66mm, t2 / t1=1.20, and S0=592mm. 2 S2 = 4725mm 2 , 100*S0 / S2=12.53, A1=0.024mm, A2=0.019mm, A1 / A2=1.26, (100*S0 / S2) / (A1 / A2)=9.92.

[0096] Example 9

[0097] The only difference in Example 9 is that t1=0.55mm, t2=0.68mm, t2 / t1=1.24, and S0=576mm. 2 S2=5250mm 2 , 100*S0 / S2=10.97, A1=0.023mm, A2=0.016mm, A1 / A2=1.44, (100*S0 / S2) / (A1 / A2)=7.63.

[0098] Example 10

[0099] Example 10 differs only in that: t1 = 0.55 mm, t2 = 0.7 mm, t2 / t1 = 1.27, S0 = 684 mm 2 , S2= 5700 mm 2 , 100*S0 / S2 = 12.00, A1 = 0.022 mm, A2 = 0.017 mm, A1 / A2 = 1.29, (100*S0 / S2) / (A1 / A2) = 9.27.

[0100] Example 11

[0101] Example 11 differs only in that: t1 = 0.6 mm, t2 = 0.8 mm, t2 / t1 = 1.33, S0 = 741 mm 2 , S2= 6840 mm 2 , 100*S0 / S2 = 10.83, A1 = 0.03 mm, A2 = 0.021 mm, A1 / A2 = 1.43, (100*S0 / S2) / (A1 / A2) = 7.58.

[0102] Example 12

[0103] Example 12 differs only in that: t1 = 0.6 mm, t2 = 0.78 mm, t2 / t1 = 1.30, S0 = 770 mm 2 , S2= 8100 mm 2 , 100*S0 / S2 = 9.51, A1 = 0.032 mm, A2 = 0.022 mm, A1 / A2 = 1.45, (100*S0 / S2) / (A1 / A2) = 6.54.

[0104] Comparative Example 1

[0105] Comparative Example 1 differs only in that: t1 = 0.5 mm, t2 = 0.58 mm, t2 / t1 = 1.16, S0 = 700 mm 2 , S2= 3600 mm 2 , 100*S0 / S2 = 19.44, A1 = 0.025 mm, A2 = 0.020 mm, A1 / A2 = 1.25, (100*S0 / S2) / (A1 / A2) = 15.56.

[0106] Comparative Example 2

[0107] Comparative Example 2 differs only in that: t1 = 0.6 mm, t2 = 0.78 mm, t2 / t1 = 1.30, S0 = 580 mm 2 , S2= 8100 mm 2, S0 = 420 mm, S2 = 2500 mm, 100 * S0 / S2 = 16.80, A1 = 0.02 mm, A2 = 0.018 mm, A1 / A2 = 1.11, (100 * S0 / S2) / (A1 / A2) = 15.12.

[0108] Comparative Example 3

[0109] Comparative Example 3 differs only in that t1 = 0.4 mm, t2 = 0.57 mm, t2 / t1 = 1.43, S0 = 420 mm 2 , S2 = 2500 mm 2 , 100 * S0 / S2 = 16.80, A1 = 0.02 mm, A2 = 0.018 mm, A1 / A2 = 1.11, (100 * S0 / S2) / (A1 / A2) = 15.12.

[0110] Comparative Example 4

[0111] Comparative Example 4 differs only in that t1 = 0.5 mm, t2 = 0.65 mm, t2 / t1 = 1.30, S0 = 560 mm 2 , S2 = 4320 mm 2 , 100 * S0 / S2 = 12.96, A1 = 0.028 mm, A2 = 0.018 mm, A1 / A2 = 1.56, (100 * S0 / S2) / (A1 / A2) = 8.33.

[0112] Performance test:

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

[0114] Table 1. Test results:

[0115]

[0116] Continuation of Table 1

[0117]

[0118]

[0119] As can be seen from the test results in Table 1, compared with the battery cells in Comparative Examples 1-4, the battery cell in the embodiment has a normally opened explosion-proof valve, smooth exhaust, no shell rupture problem, and better safety performance.

[0120] The part of the present application not described in detail is the technology known to those skilled in the art.

[0121] In the above embodiments, the description of each of the embodiments focuses on differences from other embodiments. A person of ordinary skill in the art can refer to the relevant descriptions of other embodiments for parts not described in detail in each embodiment. The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the disclosure.

[0122] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the application encompass any and all variations or modifications of the application herein described and falling within the scope of the present application. It is intended that the specification and examples be considered exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0123] It should be noted that the terms "and / or" or " / " as used herein merely indicates that a list of items is to be taken as an "or" unless otherwise stated. The terms "comprising," "including," "containing," etc. shall be construed as open-ended terms (meaning that the list of items following the term is an example of the items, and is not an exhaustive list) unless otherwise indicated. The term "consisting of" shall be construed as a closed term (meaning that the list of items following the term is an exhaustive list of the items) unless otherwise indicated.

[0124] In the DETAILED DESCRIPTION and in the claims, a list of items joined by the term "at least one of" or "one or more of" can mean any single one of the items in the list, or combinations of any of the items in the list. For example, if the list of items includes A, B, and C, the phrases "at least one of A, B, and C" or "one or more 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.

[0125] It is to be understood that the application is not limited to the precise construction herein described and as shown in the attached drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the present application. The scope of the application is to be interpreted only by the appended claims.

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 disposed on the cover plate, and the end face of the explosion-proof valve is provided with a groove, and one side of the groove forms an opening surface; 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. The average grain size of the substrate material is A2, and the average grain size of the heat-affected zone material is A1, wherein A1 and A2 satisfy: 1.0≤A1 / A2≤1.5; 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. Wherein, S0 and S1 satisfy: 5≤(100×S0 / S2) / (A1 / A2)≤15.

2. The battery cell according to claim 1, characterized in that, In the height direction of the housing, the thickness of the welding protrusion is t2, and the thickness of the substrate is t1, wherein t1 and t2 satisfy: 1.1≤t2 / t1≤2.

0.

3. The battery cell according to claim 2, characterized in that, The value of t1 is in the range of 0.25mm ≤ t1 ≤ 0.6mm; And / or, the value of t2 is in the range of 0.4mm≤t2≤0.8mm.

4. The battery cell according to claim 1, characterized in that, In the width direction of the housing, the width of the welding protrusion is 2mm to 4mm.

5. The battery cell according to claim 1, characterized in that, In the width direction of the housing, the width of the heat-affected zone located on either side of the weld protrusion is 1mm to 2mm.

6. The battery cell according to claim 1, characterized in that, The tensile strength of the substrate is Rm, wherein 190MPa≤Rm≤245MPa.

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

8. The battery cell according to any one of claims 1 to 7, characterized in that, It also includes pole posts and pole groups; The pole post is disposed on the cover plate, and the pole assembly is disposed in the housing.

9. A battery pack, characterized in that, include: The battery cell according to any one of claims 1 to 8.

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