Battery cell and battery pack

Abstract

The invention 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; in the width direction of the shell, heat affected zones are arranged on the base material on the two sides of the welding convex part respectively; 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 meet the condition that A1 / A2 is larger than or equal to 1.0 and smaller than or equal to 1.5. According to the battery cell disclosed by the invention, the influence of the welding temperature on the base material in the welding process can be well controlled, so that the shell has good structural strength and is not easy to crack 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 batteries, 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 pressure relief valve can be normally opened. If the parameters of the pressure relief valve and the shell are not reasonably designed, the risk of the pressure relief valve not being normally opened or the shell being broken may occur. 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 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 prone to cracking and damage, thereby effectively improving the safety performance of the battery cell.

[0004] To solve the above technical problems, the present application is implemented as follows: According to one aspect of the present application, the present application provides a battery cell, comprising: a shell comprising a base material; a cover plate arranged at an open end of the shell; a welding protrusion is arranged on the base material in the length direction of the shell; and a heat-affected zone is arranged on the base material on both sides of the welding protrusion 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 the A1 and A2 satisfy: 1.0≤A1 / A2≤1.5.

[0005] In some embodiments, a pressure relief valve is further included; The pressure relief valve is arranged on the cover plate, and a notch is arranged on the end face of the pressure relief valve, and the notch is surrounded by an opening face on one side; In the thickness direction of the cover plate, the projection area of the cover plate is S2; and in the thickness direction of the pressure relief valve, the projection area of the opening face is S0. Wherein, the S0 and S1 satisfy: 5≤(100*S0 / S2) / (A1 / A2)≤15.

[0006] 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, and the t1 and t2 satisfy: 1.1≤t2 / t1≤2.0.

[0007] In some embodiments, the t1 is in the range of 0.25mm≤t1≤0.6mm.

[0008] In some embodiments, the t2 is in the range of 0.4mm≤t2≤0.8mm.

[0009] In some embodiments, the weld protrusion has a width in the width direction of the shell of 2mm~4mm.

[0010] In some embodiments, the heat affected zone on either side of the weld protrusion has a width in the width direction of the shell of 1mm~2mm.

[0011] In some embodiments, the base material has a tensile strength Rm, wherein 190Mpa≤Rm≤245Mpa.

[0012] In some embodiments, the weld protrusion is formed by welding the base material, and the welding has a power of 10kW~12kW and a speed of 40m / min~50m / min.

[0013] In some embodiments, the battery pack further comprises a pole and a pole group. The pole is disposed on the cover plate, and the pole group is disposed in the shell.

[0014] According to a 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.

[0015] The technical solutions of the present application have at least the following beneficial effects: 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.

[0016] 2. In the preferred embodiments of the present application, by limiting the relationship between the area of the designed 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 (100*S0 / S2) / (A1 / A2) within a certain range, the safety performance of the battery cell can be well improved, the heat affected zone has good structural strength, the opening surface can be normally opened for exhaust pressure relief, and the shell will not crack.

[0017] Additional aspects and advantages of the present application will be partially given in the following description, partially will become obvious from the following description, or will be understood by the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments consistent with the application and, together with the description, further serve to explain the principles of the application.

[0019] Figure 1 A schematic view of a housing structure of the battery cell is shown.

[0020] Figure 2 A schematic view of a side view structure of the housing of the battery cell is shown.

[0021] Figure 3 A schematic view of a partial enlarged structure of the middle housing is shown. Figure 2 A schematic view of a partial enlarged structure of the middle housing is shown.

[0022] Figure 4 A schematic view of a planar structure of the housing of the battery cell is shown.

[0023] Figure 5 A metallographic map of the welding convex part and the heat-affected zone of the housing base material is shown.

[0024] Figure 6 An enlarged map of the welding convex part of the housing base material is shown.

[0025] Figure 7 A schematic view of an explosion-proof valve structure of the battery cell is shown.

[0026] Figure 8 A schematic view of a battery cell structure is shown.

[0027] Explanation of reference numerals: 10 - battery cell 100 - housing; 110 - base material; 120 - welding convex part; 130 - heat-affected zone 200 - cover plate; 300 - pole; 400 - pole group 500 - explosion-proof valve; 510 - notch; 520 - opening surface; 530 - transition part; 540 - skirt

[0028] The specific embodiments of the application have been shown and described in the foregoing drawings and specification, it being understood that the application is not limited to the embodiments shown and described, but rather, includes all embodiments consistent with the claimed concept. DETAILED DESCRIPTION

[0029] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes can not be described again in some examples. The embodiments of the present application will be described below with reference to the accompanying drawings.

[0030] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the present application. Any numerical values need not be a precision value, unless expressly indicated as such. In this application, the use of "about" means that a value can be the exact value or close to the value within a range of values. For numerical ranges, the endpoints are included in the ranges.

[0031] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, if not specifically stated.

[0032] 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.

[0033] First, the terms appearing in the present application are explained: Grain size: refers to the size of a single grain in the product. The classification of grain size is often determined according to the structure type of the product and the composition of the material, 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.

[0034] Average grain size, the following methods can be used: 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.

[0035] Chopping line method: by using a straight line of a certain length to cut through the grain, the average length of a grain cut through is calculated. Let the length of the straight line be L, and the total number of grains cut through be N, then the average grain size is L / N.

[0036] Jade software: using Scherrer formula, the average grain size is calculated by the half-height width of the diffraction peak.

[0037] The shell is usually formed by winding and bending a metal foil and then welding, and a welding area is formed on the metal foil during the welding process. The metal foil near the welding area is affected by the welding heat, and the rigidity, strength or metal grain of the area is changed. 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 be opened to release pressure, but if the welding process has a great 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 be broken.

[0038] 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, thereby effectively improving the safety performance of the electric core.

[0039] 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.

[0040] Reference Figure 1 The shell 100 is made of a base material 110 such as aluminum foil, copper foil or aluminum alloy. For example, 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 a metal material such as aluminum foil, copper foil or aluminum alloy. It can be understood that the cover plate 200 is provided with upper and lower plastic parts made of insulating material and a sealing member on both sides, and the present application does not make specific limitations on this. The shell 100 and the cover plate 200 form a containing space, and a pole group 400 can be arranged in the containing space.

[0041] Reference Figure 2 and Figure 3 The welding protrusion 120 is formed by welding the base material 110, and the base material 110 made of a metal material has a heat conduction effect. Therefore, in the width direction of the shell 100, a heat-affected zone 130 is formed on the base material 110 on both sides of the welding protrusion 120. For example, as shown in Figure 5The metallographic map shows that the middle part is the welding convex part 120, and the two sides are heat affected zones 130. During the process of forming the welding convex part 120 from the welding base material 110, the high temperature generated by welding has a great influence on the base material 110 near the two sides of the welding convex part 120, forming the heat affected zone 130. The high temperature will affect the grain size of the metal, causing the grain to grow again or recrystallize, etc. Therefore, when designing and manufacturing the shell 100, the average grain size of the base material 110 is A2, the average grain size of the heat affected zone 130 is A1, and the ratio of A1 and A2 can be any one of 1.0, 1.05, 1.1, 1.14, 1.2, 1.3, 1.4 or 1.5 or any point value between any two of them. By limiting the ratio range of the average grain size of the base material 110 and the heat affected zone 130, the shell 100 can have certain strength, and the structural strength of the welding convex part 120 and the heat affected zone 130 of the shell 100 will not be too low, so that when thermal runaway occurs inside the battery cell, the heat affected zone 130 of the shell 100 will not crack, causing the cell side to spray, fire and explosion, etc. Safety problems, so that the explosion-proof valve 500 on the battery cell can support opening and pressure relief. In this way, the battery cell can better ensure high safety performance. If the ratio of A1 and A2 is greater than the above range, it indicates that when the welding convex part 120 is formed by welding, the high temperature generated by welding has a great influence on the heat affected zone 130, causing the grain of the heat affected zone 130 to be coarse, thereby reducing the structural strength of the heat affected zone 130, and possibly causing the explosion-proof valve 500 to not open normally when the battery cell is in thermal runaway, and the shell 100 of the heat affected zone 130 to crack, which is prone to cause safety accidents. If the ratio of A1 and A2 is less than the above range, that is, the average grain size of the base material 110 is larger, which may reduce the overall structural strength of the shell 100. In addition to the shell 100 being prone to cracking when the battery cell is in thermal runaway, the shell 100 is prone to damage or deformation when the battery cell is in collision, which may cause damage to the cell group 400 inside the battery cell.

[0042] The battery cell provided by the present application can limit the ratio range of the average grain size of the base material and the heat affected zone on the shell, thereby well controlling the influence of the welding temperature on the base material during the welding process, making the shell have good structural strength and being not easy to crack or break, and effectively improving the safety performance of the battery cell.

[0043] In some embodiments, the explosion-proof valve 500 is further included; the explosion-proof valve 500 is arranged on the cover plate 200, and the end surface of the explosion-proof valve 500 is provided with a notch 510, and one side of the notch 510 is surrounded to form an opening surface 520; in the thickness direction of the cover plate 200, the projection area of the cover plate 200 is S2; in the thickness direction of the explosion-proof valve 500, the projection area of the opening surface 520 is S0; wherein S0 and S1 satisfy: 5≤(100*S0 / S2) / (A1 / A2)≤15.

[0044] Reference 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. The notch 510 can be arranged on the end face of the explosion-proof valve 500 close to the pole group 400, or can be arranged on the end face of the explosion-proof valve 500 away from the pole group 400. One side of the notch 510 is surrounded to form an opening face 520. It can be understood that the other side of the notch 510 is provided with a transition part 530, and a skirt 540 is arranged around the transition part 530. In the thickness direction of the cover plate 200, the projected area of the cover plate 200 is S2, and if the surface of the cover plate 200 is flat without concave-convex, the surface area of the cover plate 200 away from the shell 100 is S2. In the thickness direction of the explosion-proof valve 500, the projected area of the opening face 520 is S0, and the ratio of (100*S0 / S2) / (A1 / A2) can be any one of 5, 5.5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15, or any point value between any two of them. By limiting the range of the above ratio, the relationship between the opening face 520 of the explosion-proof valve 500 and the cover plate 200, and the base material 110 and the heat-affected zone 130 is controlled, which can further improve the safety performance of the battery cell. After the thermal runaway occurs in the battery cell, the opening face 520 can normally open and release pressure, and the shell 100 is not cracked. If it is less than the above range, the area of the opening face 520 can be too small, the grain size difference between the base material 110 and the heat-affected zone 130 on the shell 100 is too large, the structural strength of the shell 100 is poor, and the heat-affected zone 130 is easy to crack. If it is greater than the above range, the area of the opening face 520 is large, the grain size difference between the base material 110 and the heat-affected zone 130 on the shell 100 is small, the structural strength of the shell 100 as a whole is uniform and high, and is not easy to crack, but under the same conditions, it can cause abnormal opening of the explosion-proof valve 500, which is also not conducive to the safety performance of the battery cell.

[0045] In some embodiments, in the 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, and t1 and t2 satisfy: 1.1≤t2 / t1≤2.0.

[0046] Reference 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. 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, and 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.

[0047] In some embodiments, t1 is in the range of 0.25mm≤t1≤0.6mm.

[0048] 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; limiting the thickness range of the base material 110 can well guarantee that the shell 100 has 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.

[0049] In some embodiments, t2 is in the range of 0.4mm≤t2≤0.8mm.

[0050] 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 convex part 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.

[0051] In some embodiments, in the width direction of the shell 100, the width of the welding convex part 120 is 2 mm to 4 mm.

[0052] Reference Figure 3 In the width direction of the shell 100, the width of the welding convex part 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 convex part 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 convex part 120 position is not firm after welding and is prone to cracking.

[0053] 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 convex part 120 is 1 mm to 2 mm.

[0054] 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 convex part 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.

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

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] In some embodiments of the present application, a battery pack is also provided, which comprises the battery cell in any of the above embodiments.

[0062] 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.

[0063] 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.

[0064] Embodiment 1 In Example 1, the individual parameters of 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.

[0065] Example 2 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.

[0066] Example 3 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.

[0067] Example 4 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.

[0068] Example 5 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 = 0.02 mm, A2 = 0.015 mm, A1 / A2 = 1.33, (100*S0 / S2) / (A1 / A2) = 7.50.

[0069] Example 6 Example 6 differs only in that: t1=0.5 mm, t2=0.58 mm, t2 / t1=1.16, S0=512 mm 2 , S2=3600 mm 2 , 100*S0 / S2=14.22, A1=0.025 mm, A2=0.020 mm, A1 / A2=1.25, (100*S0 / S2) / (A1 / A2)=11.38.

[0070] Example 7 Example 7 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=0.022 mm, A2=0.018 mm, A1 / A2=1.22, (100*S0 / S2) / (A1 / A2)=10.61.

[0071] Example 8 Example 8 differs only in that: t1=0.55 mm, t2=0.66 mm, t2 / t1=1.20, S0=592 mm 2 , S2=4725 mm 2 , 100*S0 / S2=12.53, A1=0.024 mm, A2=0.019 mm, A1 / A2=1.26, (100*S0 / S2) / (A1 / A2)=9.92.

[0072] Example 9 Example 9 differs only in that: t1=0.55 mm, t2=0.68 mm, t2 / t1=1.24, S0=576 mm 2 , S2=5250 mm 2 , 100*S0 / S2=10.97, A1=0.023 mm, A2=0.016 mm, A1 / A2=1.44, (100*S0 / S2) / (A1 / A2)=7.63.

[0073] Example 10 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.

[0074] Example 11 Example 11 differs only in that: t1 = 0.6 mm, t2 = 0.8 mm, t2 / t1 = 1.33, S0 = 741 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.

[0075] Example 12 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.

[0076] Comparative Example 1 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.

[0077] Comparative Example 2 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 , 100*S0 / S2= 7.16, A1= 0.032 mm, A2= 0.022 mm, A1 / A2= 1.45, (100*S0 / S2) / (A1 / A2)= 4.92.

[0078] Comparative Example 3 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=0.02mm, A2=0.018mm, A1 / A2=1.11, (100*S0 / S2) / (A1 / A2)=15.12.

[0079] Comparative Example 4 Comparative Example 4 differs only in that t1=0.5mm, t2=0.65mm, t2 / t1=1.30, S0=560mm 2 , S2=4320mm 2 , 100*S0 / S2=12.96, A1=0.028mm, A2=0.018mm, A1 / A2=1.56, (100*S0 / S2) / (A1 / A2)=8.33.

[0080] Performance test: 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.

[0081] Table 1. Test results: Table 1 continued 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, and no shell rupture problem occurs, and has better safety performance.

[0082] The part of the present application not described in detail is the technology known to the person skilled in the art.

[0083] In the above embodiments, the description of each embodiment has its own emphasis, and the part not described in detail in a certain embodiment can be referred to the related description of other embodiments. The technical features of the above embodiments can be combined arbitrarily, and in order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.

[0084] Other embodiments of the present application will be readily apparent to those skilled in the art in view of the description, appended claims, and accompanying drawings. The present application is intended to include any variations, uses, or adaptations of the application following, in general, the principles of the application and including such steps and features to the extent that they exist in the prior art. The specification and examples given are considered exemplary only, with the true scope and spirit of the application indicated by the following claims.

[0085] It should be noted that the terms "and / or" or " / " as used herein merely describes associated objects under an associative relationship, that is, there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist together, B exists 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.

[0086] In the DETAILED DESCRIPTION and in the claims, a list of items connected by the term "at least one of" or "one or more of" can mean any combination of the items in the list. For example, if the items A, B, and C are listed, 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. In another example, if items A, B, and C are listed, the phrase "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. The items A can include a single element or multiple elements. The items B can include a single element or multiple elements. The items C can include a single element or multiple elements.

[0087] It should be understood that the application is not limited to the precise construction that has been described above and illustrated in the accompanying drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the application is limited only by the claims that follow.

Claims

1. An electric cell, characterized by, include: The housing, including the base material; A cover plate is provided at the open end of the housing; 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. A1 and A2 satisfy: 1.0≤A1 / A2≤1.

5.

2. The electric cell of claim 1, wherein, It also includes explosion-proof valves; The 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; 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.

3. The electric cell of claim 1, wherein, 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.

4. The cell of claim 3, wherein, 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.

5. The electric cell of claim 1, wherein, In the width direction of the housing, the width of the welding protrusion is 2mm to 4mm.

6. The electric cell of claim 1, wherein, 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.

7. The electric cell of claim 1, wherein, The tensile strength of the substrate is Rm, wherein 190 MPa ≤ Rm ≤ 245 MPa.

8. The electric cell of claim 1, wherein, 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.

9. The battery cell of any one of claims 1-8, wherein, 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.

10. A battery pack, characterized by, include: The battery cell according to any one of claims 1 to 9.

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