Battery pack and electric device

Abstract

The application relates to the technical field of batteries, and discloses a battery pack and an electric device, which comprise: a battery, a shell of the battery having a first wall, an explosion-proof valve and a pole assembly being arranged on the first wall, the explosion-proof valve having a weak portion, a battery core comprising a battery core body and a current lead-out end, the current lead-out end being welded with a first end face to form a first welding mark; and a conductive row, the battery being provided with at least two, the two batteries being electrically connected through the conductive row, the conductive row being welded with a second end face to form a second welding mark; wherein the minimum distance between the welding mark edge of the first welding mark and the second welding mark closest to the edge of the weak portion and the edge of the weak portion is d, the minimum distance between the first welding mark and the second welding mark is k, and 0.021<=k / d<=0.392 is satisfied. The application reduces the influence of heat generated at the pole assembly of the battery on the explosion-proof valve, reduces the risk of abnormal opening of the explosion-proof valve, guarantees the structural strength of the pole assembly after the first welding mark and the second welding mark are welded, and avoids the fracture failure of the pole assembly.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically to battery packs and electrical devices. Background Technology

[0002] As battery technology continues to advance, the requirements for its safety performance are also increasing. Battery casings typically have explosion-proof valves. In the event of thermal runaway caused by a short circuit, impact, or other abnormal conditions, the high-temperature, high-pressure gas generated inside the battery will break through the explosion-proof valve, thereby releasing pressure and preventing more serious safety accidents such as battery explosions. However, with battery use, the explosion-proof valves may open abnormally, affecting battery safety. Summary of the Invention

[0003] This invention provides a battery pack and an electrical device to solve the problem in the prior art where explosion-proof valves open abnormally, affecting the safety of battery use.

[0004] In a first aspect, the present invention provides a battery pack, comprising: A battery includes a casing, an explosion-proof valve, a terminal assembly, and a battery cell. The casing encloses a receiving space, and the battery cell is disposed within the receiving space. The casing has a first wall. The explosion-proof valve and the terminal assembly are spaced apart from each other along a first direction on the first wall. The explosion-proof valve has a weak portion, the thickness of which is less than the thickness of the first wall, so that when the internal pressure of the battery reaches a certain level, the weak portion is broken through to release pressure. Along the thickness direction of the first wall, the terminal assembly has a first end face close to the battery cell and a second end face away from the battery cell. The battery cell includes a cell body and a current lead-out terminal electrically connected to the cell body. The current lead-out terminal is welded to the first end face to form a first solder mark. A conductive busbar is provided, and at least two batteries are provided. The at least two batteries are electrically connected through the conductive busbar. The conductive busbar is welded to the second end face to form a second solder mark. Wherein, along the first direction, the minimum distance between the edge of the first solder mark and the edge of the weak part closest to the weak part is d mm, and along the thickness direction of the first wall, the minimum distance between the first solder mark and the second solder mark is k mm, satisfying 0.021≤k / d≤0.392.

[0005] Beneficial effects: By limiting the value relationship between the minimum heat transfer path length d mm between the first and second weld marks and the weak part, and the minimum distance k mm between the first and second weld marks, the influence of heat generation at the terminal assembly on the explosion-proof valve during battery charge and discharge cycles is reduced. This reduces the risk of abnormal valve opening while ensuring the structural strength of the terminal assembly after the first and second weld marks are welded, thus preventing the terminal assembly from breaking and failing. Specifically, if the value of k / d is too large, the heat transfer path between the first and / or second solder marks and the weak part is too short. During the battery charge and discharge cycle, the heat generated at the terminal assembly is easily transferred to the weak part of the explosion-proof valve, causing the structural strength of the explosion-proof valve to decrease under high temperature. This reduces the ultimate stress required for the explosion-proof valve to open, easily leading to abnormal opening of the explosion-proof valve and affecting the safety performance of the battery. If the value of k / d is too small, the distance between the first and second solder marks is too close. The welding heat of the first and second solder marks is too concentrated at the terminal assembly, affecting the structural strength of the terminal assembly and increasing the risk of breakage failure. This leads to increased resistance or current interruption, affecting the current transmission of the battery.

[0006] Secondly, the present invention also provides an electrical device including the aforementioned battery pack. Attached Figure Description

[0007] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the connection structure between a battery and a busbar according to an embodiment of the present invention; Figure 2 for Figure 1 A partially enlarged schematic diagram of the explosion-proof valve and terminal assembly in the battery pack shown; Figure 3 This is a schematic diagram of the structure of a first solder mark and a second solder mark according to an embodiment of the present invention; Figure 4 This is a schematic diagram of another first solder mark and a second solder mark according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of another first solder mark and a second solder mark according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of a first solder mark and a second solder mark projected onto a projection plane perpendicular to the thickness direction, according to an embodiment of the present invention. Figure 7 This is a schematic diagram of the orthographic projection of the first and second solder marks on a projection plane perpendicular to the thickness direction, according to another embodiment of the present invention. Figure 8 This is a schematic diagram of the structure of a battery according to an embodiment of the present invention; Figure 9 for Figure 8 A top view of the battery shown; Figure 10 for Figure 9 A cross-sectional view along the AA direction; Figure 11 for Figure 10 A magnified view of a portion of point B in the middle; Figure 12 This is a schematic diagram of the structure of a first solder mark and a first end face projected onto a projection plane perpendicular to the thickness direction according to an embodiment of the present invention. Figure 13 This is a schematic diagram of the structure of a second solder mark and a second end face projected onto a projection plane perpendicular to the thickness direction, according to an embodiment of the present invention. Figure 14 This is a schematic diagram of the layout structure of an electrode assembly and an explosion-proof valve on the housing according to an embodiment of the present invention; Figure 15 This is a schematic diagram of the layout structure of another pole assembly and explosion-proof valve on the housing according to another embodiment of the present invention; Figure 16 This is a schematic diagram of the structure of another explosion-proof valve according to an embodiment of the present invention; Figure 17 This is a schematic diagram showing the positional relationship between a first solder mark and a weak part according to an embodiment of the present invention; Figure 18 This is a schematic diagram showing the positional relationship between the first solder mark and the weak part in another embodiment of the present invention; Figure 19 This is a schematic diagram illustrating the positional relationship between the first solder mark and the weak point in another embodiment of the present invention; Figure 20 This is a schematic diagram illustrating the positional relationship between the first solder mark and the weak part in another embodiment of the present invention; Figure 21 This is a schematic diagram of the structure of a current lead-out terminal according to an embodiment of the present invention; Figure 22 This is a schematic diagram of another current lead-out terminal according to an embodiment of the present invention; Figure 23 for Figure 22 A partially enlarged schematic diagram of the intermediate connector and electrode tab; Figure 24 This is a top view of another battery according to an embodiment of the present invention; Figure 25 for Figure 24 A cross-sectional view along the CC direction; Figure 26 for Figure 25 A magnified view of a portion of point D in the middle; Figure 27 This is a schematic diagram of the structure of the first solder mark located near the weak point in an embodiment of the present invention; Figure 28 This is a schematic diagram of the structure of the second solder mark located near the weak point in an embodiment of the present invention; Figure 29 This is a schematic diagram of the structure of a battery pack according to an embodiment of the present invention; Figure 30 for Figure 29 A top view of the battery pack shown; Figure 31 for Figure 30 Partial sectional view along the EE direction; Figure 32 This is a schematic diagram of the structure of another battery according to an embodiment of the present invention; Figure 33 for Figure 32 A top view of the battery shown; Figure 34 for Figure 33 A cross-sectional view along the FF direction; Figure 35 This is a schematic diagram of the structure of another explosion-proof valve according to an embodiment of the present invention.

[0009] Explanation of reference numerals in the attached figures: 1. Battery; 11. Outer shell; 111. First wall; 1111. Inner wall surface; 1112. Main body of the wall; 1113. Protrusion; 11131. Fastening part; 11132. Connecting part; 112. Second wall; 113. Shell; 114. Cover plate; 12. Explosion-proof valve; 121. Weak part; 122. Groove; 123. Opening area; 124. Reinforcing rib; 125. Reinforcing area; 13. Terminal assembly; 131. First end face; 132. Second end face; 133. Terminal; 134. Riveting block; 14. Battery cell; 141. Battery cell body; 142. Current lead-out terminal; 1421. Tab; 14211. Tab layer; 1422. Adapter piece; 15. First solder mark; 16. Insulating barrier; 2. Conductive busbar; 3. Second solder mark; 10. Battery pack. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] The following is combined Figures 1 to 35 The following describes embodiments of the present invention.

[0012] According to an embodiment of the present invention, in one aspect, a battery pack 10 is provided, comprising: Battery 1 includes a casing 11, an explosion-proof valve 12, a terminal assembly 13, and a battery cell 14. The casing 11 encloses a receiving space, and the battery cell 14 is disposed within the receiving space. The casing 11 has a first wall 111. The explosion-proof valve 12 and the terminal assembly 13 are spaced apart from each other along a first direction on the first wall 111. The explosion-proof valve 12 has a weak part 121, the thickness of which is less than the thickness of the first wall, so that when the battery reaches a certain pressure, it breaks through the weak part to release pressure. Along the thickness direction of the first wall 111, the terminal assembly 13 has a first end face 131 close to the battery cell 14 and a second end face 132 away from the battery cell 14. The battery cell 14 includes a battery cell body 141 and a current lead-out terminal 142 electrically connected to the battery cell body 141. The current lead-out terminal 142 is welded to the first end face 131 to form a first solder mark 15. The conductive bus 2 is provided with at least two batteries 1. The at least two batteries 1 are electrically connected through the conductive bus 2. The conductive bus 2 is welded to the second end face 132 to form a second weld mark 3. Wherein, along the first direction, the minimum distance between the edge of the first weld mark 15 and the second weld mark 3 closest to the weak part and the edge of the weak part 121 is d mm, and along the thickness direction of the first wall 111, the minimum distance between the first weld mark 15 and the second weld mark 3 is k mm, satisfying 0.021≤k / d≤0.392.

[0013] The battery 1 of this embodiment limits the relationship between the length d mm of the minimum heat transfer path between the first solder mark 15 and the second solder mark 3 and the weak part 121 and the minimum distance k mm between the first solder mark 15 and the second solder mark 3. This reduces the impact of heat generation at the terminal assembly 13 on the explosion-proof valve 12 during the charge and discharge cycle of the battery 1, thereby reducing the risk of abnormal opening of the explosion-proof valve 12 and ensuring the structural strength of the terminal assembly 13 after the first solder mark 15 and the second solder mark 3 are welded, thus preventing the terminal assembly 13 from breaking and failing.

[0014] Specifically, if the value of k / d is too large, the heat transfer path between the first weld mark 15 and / or the second weld mark 3 and the weak part 121 may be too short, and the distance between the first weld mark 15 and the second weld mark 3 may be too far. The current transmission path is long, the heat dissipation rate inside the battery is slow, and the temperature rise is too fast. As a result, the heat generated by the terminal assembly 13 at the first weld mark and the second weld mark during the charge and discharge cycle of the battery 1 is easily transferred to the weak part 121 of the explosion-proof valve 12. This causes the structural strength of the explosion-proof valve 12 to decrease under high temperature, which in turn reduces the ultimate stress required for the explosion-proof valve 12 to open. This can easily lead to abnormal opening of the explosion-proof valve 12 and affect the safety performance of the battery 1. If the value of k / d is too small, the distance between the first weld mark 15 and the second weld mark 3 may be too close. The welding heat of the first weld mark 15 and the welding heat of the second weld mark 3 may be too concentrated at the terminal assembly 13, which may affect the structural strength of the terminal assembly 13 and increase the risk of breakage failure of the terminal assembly 13. This may lead to increased resistance or current interruption and affect the current transmission of the battery 1.

[0015] Preferably, the value of k / d satisfies 0.03≤k / d≤0.257.

[0016] Optionally, k / d can be any value from 0.021, 0.025, 0.03, 0.05, 0.1, 0.15, 0.2, 0.25, 0.257, 0.3, 0.35, 0.38, 0.392, or a value between any two values.

[0017] It is worth noting that when battery 1 experiences safety issues such as short circuits or thermal runaway, high-temperature and high-pressure gas is generated inside battery 1. By incorporating an explosion-proof valve 12, when the internal pressure of battery 1 reaches a certain value (i.e., the predetermined opening pressure of the explosion-proof valve 12), the high-temperature and high-pressure gas will break through the thinned area, causing the explosion-proof valve 12 to open and achieving directional pressure relief of battery 1 at the explosion-proof valve 12. However, researchers have discovered that during the use of battery 1, the explosion-proof valve 12 may open abnormally; that is, the explosion-proof valve 12 may open before the internal pressure of battery 1 reaches the predetermined opening pressure.

[0018] The study found that the abnormal opening of the explosion-proof valve 12 was mainly caused by heat. Under the influence of high temperature, the ultimate stress required for the explosion-proof valve 12 to open is reduced, resulting in the actual opening pressure of the explosion-proof valve 12 being less than the predetermined opening pressure, thus causing the explosion-proof valve 12 to open abnormally. In particular, with the increasing market demand for fast charging of battery 1, under the high-rate charging and discharging strategy, the high-temperature gas inside battery 1 will accumulate rapidly during the cycle of battery 1. In addition, the terminal assembly 13 is the main component for realizing the current transmission between the inside and outside of battery 1 and is the main heat source of battery 1. Furthermore, the electrical connection between the terminal assembly 13 and the cell 14, as well as the electrical connection between the terminal assembly 13 and external devices (other batteries 1 or electrical equipment), is usually welded, resulting in a large current transmission impedance and more serious heat generation. In the related technology, the explosion-proof valve 12 and the terminal assembly 13 in battery 1 are usually set on the same side of battery 1. The heat generated by the terminal assembly 13 is easily transferred to the explosion-proof valve 12, causing the explosion-proof valve 12 to be in a high-temperature environment for a long time. This causes the ultimate stress required for the explosion-proof valve 12 to open to gradually decrease, which can easily cause the explosion-proof valve 12 to open abnormally.

[0019] Therefore, in this embodiment, on the one hand, by controlling the minimum distance kmm between the first solder mark 15 and the second solder mark 3, the size of the current path between the first solder mark 15 and the second solder mark 3 is adjusted, thereby reducing the heat generated during the current transmission process. On the other hand, by controlling the length dmm of the minimum heat transfer path between the first solder mark 15 and the second solder mark 3 and the weak part 121, the heat generated at the pole assembly 13 is transferred to the weak area, thereby reducing the heat value. In summary, in this embodiment, by limiting the value of k / d, the impact of the heat generated at the pole assembly 13 on the explosion-proof valve 12 is reduced, ensuring the structural strength of the explosion-proof valve 12, reducing the risk of abnormal valve opening of the explosion-proof valve 12, and at the same time, ensuring the structural reliability of the pole assembly 13 itself and ensuring the current transmission effect.

[0020] It should be noted that the first direction refers to the spacing direction of the explosion-proof valve and the pole assembly on the first wall. It can be the length direction of the first wall, the width direction of the first wall, or other diagonal directions (e.g., a diagonal direction). In this embodiment, the first direction is the length direction of the first wall.

[0021] It is worth noting that, such as Figures 2 to 5 As shown, the minimum distance k mm between the first solder mark 15 and the second solder mark 3 along the thickness direction of the first wall 111 refers to the distance between one end of the first solder mark 15 inside the pole post assembly 13 (that is, the end of the first solder mark 15 close to the second solder mark 3) and one end of the second solder mark 3 inside the pole post assembly 13 (that is, the end of the second solder mark 3 close to the first solder mark 15) along the thickness direction of the first wall 111.

[0022] It is worth noting that, such as Figure 2As shown, the heat transfer path from the solder mark to the weak part 121 refers to the extension direction from the edge of the solder mark through the pole post assembly 13 to the first wall 111, and then along the first wall 111 from the pole post assembly 13 to the edge of the weak part 121. Specifically, for the first solder mark 15, along the thickness direction of the first wall 111, the distance between the first solder mark 15 and the side of the first wall 111 facing the battery cell 14 is L11 mm, and along the length direction of the first wall 111 (i.e., the first direction), the distance between the edge of the first solder mark 15 and the edge of the weak portion 121 is L12 mm. Therefore, the length of the heat transfer path between the first solder mark 15 and the weak portion 121 is D1 = L11 + L12. For the second solder mark 3, along the thickness direction of the first wall 111, the distance between the second solder mark 3 and the side of the first wall 111 away from the battery cell 14 is L21 mm, and along the length direction of the first wall 111 (i.e., the first direction), the distance between the edge of the second solder mark 3 and the edge of the weak portion 121 is L22 mm. Therefore, the length of the heat transfer path between the second solder mark 3 and the weak portion 121 is D2 = L21 + L22. Furthermore, along the first direction, the minimum distance d mm between the edge of the first and second solder marks closest to the weak part and the edge of the weak part is the minimum of L12 mm and L22 mm, that is, d = min[L12, L22]; in addition, the values ​​of L11 and L21 satisfy: 1 ​​≤ L11 ≤ 4, and / or, 1 ≤ L21 ≤ 4.

[0023] It is worth noting that, such as Figure 11 As shown, the electrode assembly 13 can be electrode 133, which is welded to the busbar 2 to achieve current transmission. Alternatively, as... Figure 26 As shown, the pole assembly 13 includes a pole 133 and a riveting block 134. The pole 133 is installed on the first wall 111 by the riveting block 134. The conductive bus 2 can be welded to the riveting block 134 to realize current transmission.

[0024] It should be noted that the first end face 131 does not necessarily have to be the end face of the terminal assembly 13 closest to the cell 14; that is, the first end face can be the innermost end face of the terminal assembly, or it can be any other end face facing the inside of the battery. Similarly, the second end face 132 does not necessarily have to be the end face of the terminal assembly furthest from the cell 14; that is, the second end face can be the outermost end face of the terminal assembly, or it can be any other end face facing the outside of the battery. The only requirement is that the first end face can be welded to the current lead and the second end face can be welded to the busbar to achieve current transfer between the inside and outside of the battery.

[0025] Specifically, in one embodiment, such as Figure 3 and Figure 4As shown, on the projection plane perpendicular to the thickness direction of the first wall 111, the orthographic projection of the first weld mark 15 and the orthographic projection of the second weld mark 3 at least partially overlap, that is, the first weld mark 15 and the second weld mark 3 are at least partially positioned opposite each other along the thickness direction of the first wall 111. At this time, the heat superposition between the positions where the first weld mark 15 and the second weld mark 3 are positioned opposite each other in the pole post assembly 13 is severe, increasing the impact of the welding of the first weld mark 15 and the second weld mark 3 on the structural strength of the pole post assembly 13, leading to an increased risk of fracture failure. Therefore, in this embodiment, the length d mm of the minimum heat transfer path between the first weld mark 15 and the second weld mark 3 and the weak part 121, and the minimum distance k mm between the first weld mark 15 and the second weld mark 3 satisfy 0.03≤k / d≤0.392, reducing the superposition of welding heat from the first weld mark 15 and the second weld mark 3 at the pole post assembly 13, further ensuring the structural strength of the pole post assembly 13, reducing the risk of fracture failure, and ensuring the current transmission effect of the pole post assembly 13.

[0026] Furthermore, in one embodiment, such as Figure 4 As shown, on the projection plane perpendicular to the thickness direction of the first wall 111, the orthographic projection of the first solder mark 15 falls within the range of the orthographic projection of the second solder mark 3, or the orthographic projection of the second solder mark 3 falls within the range of the orthographic projection of the first solder mark 15. That is, on the projection plane perpendicular to the thickness direction of the first wall 111, the area of ​​the orthographic projection of the first solder mark 15 is smaller than the area of ​​the orthographic projection of the second solder mark 3 and falls completely within the range of the orthographic projection of the second solder mark 3; or, the area of ​​the orthographic projection of the second solder mark 3 is smaller than the area of ​​the orthographic projection of the first solder mark 15 and falls completely within the range of the orthographic projection of the first solder mark 15; or, the area of ​​the orthographic projection of the first solder mark 15 is equal to the area of ​​the orthographic projection of the second solder mark 3 and the two completely overlap. At this time, there is the shortest current path between the first solder mark 15 and the second solder mark 3, which improves the current flow effect between the cell 14 and the busbar 2, reduces the heat generated by the terminal assembly 13 during the charging and discharging of the battery 1, reduces the impact of heat on the structural strength of the explosion-proof valve 12, and ensures the reliability of the explosion-proof valve 12.

[0027] Of course, such as Figure 3 As shown, on the projection plane perpendicular to the thickness direction of the first wall 111, the orthographic projection of the first solder mark 15 and the orthographic projection of the second solder mark 3 may only partially overlap. That is, on the projection plane perpendicular to the thickness direction of the first wall 111, there is a portion where the orthographic projection of the first solder mark 15 does not overlap with the orthographic projection of the second solder mark 3, and there is a portion where the orthographic projection of the second solder mark 3 does not overlap with the orthographic projection of the first solder mark 15.

[0028] As an alternative implementation, in another embodiment, such as Figure 5As shown, on the projection plane perpendicular to the thickness direction of the first wall 111, the orthographic projection of the first solder mark 15 and the orthographic projection of the second solder mark 3 do not coincide. That is, on the projection plane perpendicular to the thickness direction of the first wall 111, the orthographic projection of the first solder mark 15 and the orthographic projection of the second solder mark 3 are completely separated.

[0029] Furthermore, in the above alternative implementations, such as Figure 5 As shown, along the first direction, the distance between the first solder mark 15 and the second solder mark 3 is e mm, satisfying 0.5≤e≤6. This setting ensures the effective transmission of current in battery 1 while reducing the risk of abnormal opening of the explosion-proof valve 12.

[0030] It is worth noting that if the value of e is too small, it can easily increase the current path from inside battery 1 to the outside, leading to increased impedance during current transmission and affecting the current transmission effect of battery 1. If the value of e is too large, it can easily cause the solder mark to be too close to the weak part 121, increasing the impact of heat on the weak part 121 at the solder mark. This can reduce the structural strength of the explosion-proof valve 12 under high temperature, thereby reducing the ultimate stress required for the explosion-proof valve 12 to open, which can easily lead to abnormal opening of the explosion-proof valve 12 and affect the safety performance of battery 1.

[0031] Preferably, the value of e satisfies 1≤e≤5.

[0032] Optionally, the value of e can be any one of 0.5, 0.8, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, or a value between any two values.

[0033] Furthermore, in the above alternative implementations, such as Figure 27 As shown, along the first direction, the first solder mark 15 is positioned closer to the weak point 121 than the second solder mark 3. That is, d = L12 < L22. The first solder mark 15 generates concentrated heat and is located inside the battery 1, resulting in poor heat dissipation. When the first solder mark 15 is close to the weak point 121, the heat influence on the weak point 121 increases, leading to a decrease in the structural strength of the explosion-proof valve 12 under high temperature. This, in turn, reduces the ultimate stress required for the explosion-proof valve 12 to open, making it prone to abnormal opening of the explosion-proof valve 12. At this time, the minimum distance k mm between the first solder mark 15 and the second solder mark 3 is made to satisfy 2.5 ≤ k ≤ 9. By further limiting the value of k, the current path between the first solder mark 15 and the second solder mark 3 is further reduced, improving the current transmission effect between the cell 14 and the conductor 2, and reducing the heat generated by the terminal assembly 13 during the charging and discharging process of the battery 1.

[0034] Or, such as Figure 28As shown, along the first direction, the second solder mark 3 is positioned closer to the weak point 121 than the first solder mark 15. That is, L12 > L22 = d. The second solder mark 3 is located outside the battery 1, providing better heat dissipation. During the charging and discharging process of the battery 1, the heat at the second solder mark 3 can be quickly dissipated to the external environment, reducing the heat impact on the weak point 121 and reducing the risk of abnormal opening of the explosion-proof valve 12.

[0035] Of course, such as Figure 2 As shown, along the first direction, the distance between the first solder mark 15 and the weak part 121 can also be the same as the distance between the second solder mark 3 and the weak part 121. That is, L12=L22=d.

[0036] In one embodiment, such as Figure 6 As shown, on the projection plane perpendicular to the thickness direction of the first wall 111, the area of ​​the orthographic projection of the first solder mark 15 is S1 mm. 2 The area of ​​the orthographic projection of the second solder mark 3 is S2 mm. 2 This satisfies S1 > S2. This configuration improves the overcurrent capacity of the cell 14 and terminal assembly 13 inside the battery 1, reduces the heat generated during the current transfer process between the current lead 142 and the terminal assembly 13, and reduces the temperature rise of the battery 1.

[0037] It is worth noting that the current lead 142 and the terminal assembly 13 are connected inside the battery 1, resulting in poor heat dissipation at the connection point. This can easily cause heat to accumulate inside the battery 1 during cycling, increasing the temperature rise of the battery 1. In contrast, the connection point between the terminal assembly 13 and the busbar 2 is located outside the battery 1, where heat dissipation is relatively better, thus having a relatively lower impact on the overall temperature rise of the battery 1. Therefore, in this embodiment, the first solder mark 15 has a larger soldering area than the second solder mark 3, reducing internal heat generation in the battery 1 and helping to control the temperature rise of the battery 1.

[0038] Specifically, in one embodiment, the area of ​​the orthographic projection of the first solder mark 15 is S1 mm. 2 The condition 15 ≤ S1 ≤ 215 is satisfied.

[0039] Optionally, S1 can be any value from 15, 20, 30, 50, 80, 100, 120, 150, 180, 200, 215 or a value between any two values.

[0040] Specifically, in one embodiment, the area of ​​the orthographic projection of the second solder mark 3 is S2 mm. 2 The condition 20 ≤ S2 ≤ 200 is satisfied.

[0041] Optionally, the value of S2 can be any one of 20, 40, 60, 80, 100, 120, 150, 180, 200 or a value between any two values.

[0042] Furthermore, in one embodiment, the area of ​​the orthographic projection of the first solder mark 15 is S1 mm. 2 The area S2 mm of the orthographic projection of the second solder mark 3 2 The following condition must be met: 5 ≤ S1 - S2 ≤ 150. This setting effectively controls the temperature rise of battery 1 while ensuring the overcurrent capacity between the terminal assembly 13 and the busbar 2.

[0043] It is worth noting that if the values ​​of S1-S2 are too small, the welding area of ​​the first solder mark 15 may be insufficient, resulting in insufficient improvement in the overcurrent capacity between the current lead 142 and the terminal assembly 13. This will still cause severe damage at the connection point between the current lead 142 and the terminal assembly 13 inside the battery 1, increasing the temperature rise of the battery 1. If the values ​​of S1-S2 are too large, the welding area of ​​the second solder mark 3 may be insufficient, leading to poor overcurrent capacity between the terminal assembly 13 and the busbar 2, affecting the overall overcurrent effect of the battery 1 and its charge / discharge performance.

[0044] Optionally, the values ​​of S1-S2 can be any one of 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, or any value between any two of them.

[0045] Of course, as an alternative implementation, in another embodiment, such as Figure 7 As shown, on the projection plane perpendicular to the thickness direction of the first wall 111, the area of ​​the orthographic projection of the first solder mark 15 is S1 mm. 2 The area of ​​the orthographic projection of the second solder mark 3 is S2 mm. 2 The condition is satisfied that S1 < S2. It is worth noting that when the battery pack 10 is subjected to vibration, if the vibration amplitudes of the two batteries 1 connected to the same conductive bar 2 are different, a tensile force will be generated on the conductive bar 2, which can easily cause the second solder mark 3 to crack. However, the battery cell 14 and the terminal assembly 13 are less stressed due to the constraint of the outer casing 11. Therefore, in this embodiment, the second solder mark 3 has a larger welding area than the first solder mark 15, which improves the welding strength of the conductive bar 2 and the terminal assembly 13 and reduces the risk of cracking of the second solder mark 3.

[0046] In one embodiment, such as Figure 11 and Figure 34As shown, the first wall 111 has a through mounting hole along its thickness direction. The pole assembly 13 is at least partially inserted through the mounting hole. The first wall 111 includes a wall body 1112 and a protrusion 1113 protruding from the wall body 1112 in the direction away from the battery cell 14. The protrusion 1113 includes a fastening part 11131 and a connecting part 11132. One end of the connecting part 11132 is connected to the fastening part 11131, and the other end of the connecting part 11132 is connected to the wall body 1112. The fastening part 11131 is pressed on the side of the pole assembly 13 away from the battery cell 14. The protrusion 1113 surrounds the mounting hole to form an inner wall surface 1111. An insulating barrier 16 is provided at least between the inner wall surface 1111 and the outer peripheral surface of the pole assembly 13. In the direction perpendicular to the thickness direction of the first wall 111, the thickness of the insulating barrier 16 is t mm, satisfying 0.3≤t≤1. This configuration reduces the risk of abnormal opening of the explosion-proof valve 12 while ensuring the overcurrent capacity of the pole assembly 13.

[0047] It is worth noting that by providing the insulating barrier 16, an insulating and sealing function is achieved between the first wall 111 and the pole assembly 13. The insulating barrier 16 can be a plastic part or a sealing ring. In addition, the insulating barrier 16 can also provide heat insulation.

[0048] Specifically, if the value of t is too small, the heat insulation effect of the insulating barrier 16 will be reduced, and the heat generated at the electrode assembly 13 will easily be transferred to the first wall 111 and reach the explosion-proof valve 12, affecting the structural strength of the explosion-proof valve 12 and leading to the risk of abnormal valve opening. If the value of t is too large, the setting of the insulating barrier 16 will easily encroach on the setting space of the electrode assembly 13, resulting in a reduction in the current-carrying area of ​​the electrode assembly 13, affecting the current-carrying capacity of the electrode assembly 13, leading to an increase in the heat generated by the electrode assembly 13 during charging and discharging, and increasing the safety risk.

[0049] Optionally, t can take any value from 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a value between any two values.

[0050] It is worth noting that the connecting part 11132 is set at a certain angle to the wall body 1112, with the angle ranging from 80° to 120°. Preferably, the connecting part 11132 is set perpendicular to the wall body 1112, that is, the angle is 90°. Furthermore, the connecting part 11132 and the wall body 1112 can be integrally connected, or they can be separate structures connected by welding.

[0051] It should be noted that the inner wall surface 1111 mentioned above can be the wall surface of the connecting part 11132 facing the outer peripheral surface of the pole post assembly 13, or it can be the wall surface of the fastening part 11131 facing the top surface of the pole post assembly 13.

[0052] Specifically, in this embodiment, the insulating barrier 16 is disposed around the outer peripheral surface of the pole post 133 and is located between the connecting part 11132 and the outer peripheral surface of the pole post 133, and between the fastening part 11131 and the outer peripheral surface of the pole post 133. The fastening part 11131 is bent relative to the connecting part 11132 and pressed onto the insulating barrier 16.

[0053] As an alternative implementation method, such as Figure 26 As shown, the electrode assembly 13 includes an electrode 133 and a riveting block 134, and the electrode 133 is mounted to the first wall 111 by the riveting block 134. Specifically, the end of the electrode 133 away from the battery cell 14 has a deformable part, and the riveting block 134 is riveted to the first wall 111 by the deformable part.

[0054] In one embodiment, such as Figure 12 As shown, on the projection plane perpendicular to the thickness direction of the first wall 111, the area of ​​the orthographic projection of the first solder mark 15 is S1 mm. 2 The area of ​​the orthographic projection of the first end face 131 is S3 mm. 2 The condition 0.1 ≤ S1 / S3 ≤ 0.6 is satisfied. This setting ensures the welding quality of the first solder mark 15 while also guaranteeing the current-carrying capacity between the battery cell 14 and the terminal assembly 13.

[0055] It is worth noting that if the values ​​of S1 / S3 are too small, the welding area of ​​the first solder mark 15 may be too small, resulting in excessive impedance during current transmission and affecting the current carrying capacity between the cell 14 and the terminal assembly 13. If the values ​​of S1 / S3 are too large, the edge of the first solder mark 15 may be too close to the edge of the first end face 131, which may lead to problems such as incomplete soldering and affect the welding quality.

[0056] Optionally, S1 / S3 can be any value from 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 or a value between any two values.

[0057] Specifically, in one embodiment, the area of ​​the orthographic projection of the first end face 131 is S3 mm. 2 The condition is satisfied that 60≤S3≤2500.

[0058] Preferably, the value of S3 satisfies 60≤S3≤404.

[0059] Optionally, the value of S3 can be any one of 60, 100, 200, 300, 400, 404, 500, 1000, 1500, 2000, 2500, or a value between any two of them.

[0060] In one embodiment, such as Figure 13As shown, on the projection plane perpendicular to the thickness direction of the first wall 111, the area of ​​the orthographic projection of the second weld mark 3 is S2 mm. 2 The area of ​​the orthographic projection of the second end face 132 is S4 mm. 2 The condition 0.1 ≤ S2 / S4 ≤ 0.5 is satisfied. This setting ensures the welding quality of the second weld mark 3 while also guaranteeing the current-carrying capacity between the pole assembly 13 and the busbar 2.

[0061] It is worth noting that if the values ​​of S2 / S4 are too small, the welding area of ​​the second weld mark 3 may be too small, resulting in excessive impedance during current transmission and affecting the current carrying capacity between the terminal assembly 13 and the busbar 2. If the values ​​of S2 / S4 are too large, the edge of the second weld mark 3 may be too close to the edge of the second end face 132, which may lead to problems such as incomplete soldering and affect the welding quality.

[0062] Optionally, the value of S2 / S4 can be any one of 0.1, 0.2, 0.3, 0.4, 0.5 or a value between any two of them.

[0063] Specifically, in one embodiment, the area of ​​the orthographic projection of the second end face 132 is S4 mm. 2 It satisfies 80≤S4≤1200.

[0064] Preferably, the value of S4 satisfies 80≤S4≤800.

[0065] Optionally, the value of S4 can be any one of 80, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200 or a value between any two values.

[0066] In one embodiment, such as Figure 8 and Figure 14 As shown, two pole post assemblies 13 are provided with opposite polarities. Each pole post assembly 13 has a first solder mark 15 and a second solder mark 3. The two pole post assemblies 13 are both disposed on the first wall 111 and spaced apart along the length of the first wall 111. The explosion-proof valve 12 is disposed between the two pole post assemblies 13 along the length of the first wall 111. This arrangement improves the uniformity of heat distribution on both sides of the explosion-proof valve 12, preventing the heat transferred by the pole post assemblies 13 from concentrating on the same side of the explosion-proof valve 12, which would lead to an abnormal reduction in the structural strength of the weak part 121, thereby further reducing the risk of abnormal valve opening of the explosion-proof valve 12.

[0067] Furthermore, in one embodiment, such as Figure 14As shown, the distance between the two electrode assemblies 13 along the length of the first wall 111 is a mm, satisfying 80≤a≤270. This configuration reduces the heat generated by the battery cell 14 while minimizing the heat generated by the two electrode assemblies 13 due to the superposition of heat on the first wall 111.

[0068] It is worth noting that if the value of 'a' is too small, the two terminal components 13 may be too close together. The heat generated by the two terminal components 13 can easily be superimposed after being transferred to the first wall 111, resulting in excessive heating of the explosion-proof valve 12, affecting the structural strength of the explosion-proof valve 12, and posing a risk of abnormal valve opening. If the value of 'a' is too large, the distance between the positive and negative tabs connected to the two terminal components 13 may be too great, resulting in an excessively long current transmission path inside the cell 14. The impedance encountered during current transmission is too large, increasing the heat generation of the cell 14 and affecting the safety performance of the battery 1.

[0069] Optionally, the value of 'a' can be any one of 80, 100, 120, 150, 180, 200, 220, 250, 270, or a value between any two of them.

[0070] As an alternative implementation, in another embodiment, such as Figure 15 As shown, two pole post assemblies 13 are provided with opposite polarities. Each pole post assembly 13 has a first solder mark 15 and a second solder mark 3 formed on it. The housing 11 also has a second wall 112 disposed opposite to the first wall 111. One pole post assembly 13 is disposed on the first wall 111, and the other pole post assembly 13 is disposed on the second wall 112. On the projection plane perpendicular to the thickness direction of the first wall, the area of ​​the orthographic projection of the first solder mark is S1 mm. 2 The area of ​​the orthographic projection of the second solder mark is S2 mm. 2 The values ​​of S1 and / or S2 are satisfied, which satisfies 30≤S1≤215 and / or 40≤S2≤200. The two pole post assemblies 13 are respectively disposed on two walls of the housing 11, and the explosion-proof valve 12 is located on the same wall as one of the pole post assemblies 13. This reduces the heat exposure of the explosion-proof valve 12 and improves its structural strength. Therefore, the values ​​of S1 and / or S2 can be further limited, ensuring the structural strength of the explosion-proof valve 12 while further improving the welding strength of the first and / or second solder marks, and enhancing the current-carrying capacity between the battery cell and the busbar.

[0071] Specifically, in one embodiment, the minimum distance d mm between the edge of the first and second solder marks closest to the weak portion and the edge of the weak portion satisfies 25 ≤ d ≤ 130. This configuration reduces the impact of heat generation at the terminal assembly 13 during the charge-discharge cycle of battery 1 on the explosion-proof valve 12, thereby reducing the risk of abnormal valve opening of the explosion-proof valve 12, while also facilitating the layout of other components on the first wall 111.

[0072] It is worth noting that if the value of d is too small, the heat transfer path between the first solder mark 15 and / or the second solder mark 3 and the weak part 121 may be too short. During the charge and discharge cycle of the battery 1, the heat generated at the terminal assembly 13 may be easily transferred to the weak part 121 of the explosion-proof valve 12, which will reduce the structural strength of the explosion-proof valve 12 under high temperature. This will reduce the ultimate stress required for the explosion-proof valve 12 to open, which may cause abnormal opening of the explosion-proof valve 12 and affect the safety performance of the battery 1. If the value of d is too large, the layout of the terminal assembly 13 and the explosion-proof valve 12 may occupy too much space on the first wall 111, which is not conducive to the arrangement of other components on the first wall 111.

[0073] Preferably, the value of d satisfies 30≤d≤110.

[0074] Optionally, d can take any value from 25, 28, 30, 35, 40, 45, 50, 55, 60, 70, 80, 90, 100, 110, 120, 130, or a value between any two values.

[0075] Specifically, in one embodiment, the minimum distance k mm between the first solder mark 15 and the second solder mark 3 satisfies 2.5 ≤ k ≤ 10. This setting reduces the current path between the first solder mark 15 and the second solder mark 3, improves the current flow effect between the cell 14 and the busbar 2, and ensures the structural strength of the electrode assembly 13 after the first solder mark 15 and the second solder mark 3 are welded, thus preventing the electrode assembly 13 from breaking and failing.

[0076] It is worth noting that if the value of k is too small, the distance between the first solder mark 15 and the second solder mark 3 may be too close, causing the welding heat of the first solder mark 15 and the welding heat of the second solder mark 3 to be too concentrated at the terminal assembly 13, affecting the structural strength of the terminal assembly 13, increasing the risk of breakage failure of the terminal assembly 13, and thus leading to increased resistance or current interruption, affecting the current transmission of battery 1. If the value of k is too large, the overcurrent path between the first solder mark 15 and the second solder mark 3 may be extended, affecting the current transmission effect between the cell 14 and the busbar 2, resulting in increased heat generation of the terminal assembly 13 during the charging and discharging of battery 1. The heat generated at the terminal assembly 13 is transferred to the weak part 121 of the explosion-proof valve 12, causing the structural strength of the explosion-proof valve 12 to decrease under high temperature, thus reducing the ultimate stress required for the explosion-proof valve 12 to open, which may easily cause abnormal opening of the explosion-proof valve 12 and affect the safety performance of battery 1.

[0077] Preferably, the value of k satisfies 2.8≤k≤8.

[0078] Optionally, k can take any value from 2.5, 2.6, 2.7, 2.8, 2.9, 3, 4, 5, 6, 7, 8, 9, 10, or a value between any two values.

[0079] In one embodiment, such as Figure 2 and Figure 16 As shown, a groove 122 is formed on one side of the weak portion 121 along the thickness direction of the first wall 111. Specifically, the groove 122 is formed by etching (punching or corroding) on ​​the explosion-proof sheet substrate, thereby thinning the thickness of the explosion-proof sheet substrate at the groove 122 to form the weak portion 121.

[0080] It is worth noting that the cross-sectional shape of the groove 122 in the direction perpendicular to the extension path of the weak part 121 can be trapezoidal, triangular, U-shaped, or square.

[0081] Specifically, in one embodiment, such as Figure 35 As shown, the groove 122 has a non-closed annular structure along the circumference, and a reinforcing region 125 is formed in the non-closed area. The thickness of the reinforcing region 125 is greater than the thickness of the weak part 121. Along the first direction, the reinforcing region 125 is located closer to the first solder mark 15 and the second solder mark 3 than the groove 122. By avoiding making the groove 122 a continuous annular shape, the structural strength of the explosion-proof valve 12 can be improved, the cracking risk of the explosion-proof valve 12 can be reduced, and the reinforcing region 125 is located closer to the solder mark, reducing the impact of the heat from the solder mark on the weak part 121 of the explosion-proof valve 12 and reducing the risk of abnormal valve opening of the explosion-proof valve 12.

[0082] Of course, as an alternative implementation, the groove 122 can also be a completely closed annular structure along the circumference.

[0083] Specifically, in one embodiment, such as Figure 2 As shown, along the thickness direction of the first wall 111, the thickness of the weak part 121 is b mm, satisfying 0.04≤b≤0.3. This configuration ensures that the explosion-proof valve 12 can open under a predetermined pressure, allowing the high-temperature, high-pressure gas inside the battery 1 to be directionally discharged, achieving timely and directional pressure relief of the battery 1. Simultaneously, it maintains the structural strength of the explosion-proof valve 12, prevents abnormal opening of the explosion-proof valve 12, and ensures its reliability.

[0084] Specifically, if the value of b is too small, the structural strength of the explosion-proof valve 12 may be insufficient. During the charging and discharging cycle of battery 1, the heat generated at the terminal assembly 13 will be transferred to the weak part 121 of the explosion-proof valve 12, causing the structural strength of the explosion-proof valve 12 to be further reduced under high temperature. This will reduce the ultimate stress required for the explosion-proof valve 12 to open, which may lead to abnormal opening of the explosion-proof valve 12 and affect the safety performance of battery 1. If the value of b is too large, the opening pressure of the explosion-proof valve 12 may be too large. When battery 1 experiences thermal runaway, the explosion-proof valve 12 may not be able to open preferentially. This may cause the weak part of the outer casing 11 to be broken, causing the high-temperature and high-pressure gas inside battery 1 to rush out from the broken part of the outer casing 11. This will prevent the high-temperature and high-pressure gas from being discharged in a directional manner, causing thermal propagation. This may cause the adjacent battery 1 to also experience thermal runaway under the influence of the high-temperature and high-pressure gas, leading to a more serious safety accident.

[0085] Optionally, b can take any value from 0.04, 0.05, 0.08, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3, or a value between any two values.

[0086] Furthermore, in one embodiment, such as Figure 2 As shown, the groove 122 is located on the side of the explosion-proof valve 12 facing away from the battery cell 14. At this time, the side of the explosion-proof valve 12 facing the battery cell 14 is a flat surface, and the explosion-proof valve 12 is subjected to a more balanced force from the high-temperature and high-pressure gas inside the battery 1, reducing the risk of abnormal opening of the explosion-proof valve 12.

[0087] Of course, as alternative implementation methods, such as Figure 16 As shown, the groove 122 can also be located on the side of the explosion-proof valve 12 facing the battery cell 14.

[0088] In one embodiment, such as Figures 17 to 20 As shown, on the projection plane perpendicular to the first direction, at least a portion of the orthographic projection of the weak portion 121 does not coincide with the orthographic projection of the first solder mark 15. This arrangement prevents the entire weak portion 121 from being completely affected by the heat generated by the first solder mark 15, further ensuring the structural strength of the explosion-proof valve 12, preventing abnormal opening of the explosion-proof valve 12, and ensuring the reliability of the explosion-proof valve 12.

[0089] It is worth noting that, such as Figure 17 As shown, on the projection plane perpendicular to the length direction of the first wall 111, along the width direction of the first wall 111, the orthographic projection of the weak portion 121 does not coincide with the orthographic projection of the first solder mark 15. Or, as... Figure 18 and Figure 19As shown, on the projection plane perpendicular to the length direction of the first wall 111, along the width direction of the first wall 111, a portion of the orthographic projection of the weak portion 121 coincides with the orthographic projection of the first solder mark 15; at this time, along the width direction of the first wall 111, a portion of the orthographic projection of the first solder mark 15 may not coincide with the orthographic projection of the weak portion 121 (e.g. Figure 18 As shown), it can also be that the orthographic projection of the first solder mark 15 falls completely within the orthographic projection of the weak portion 121 and the width of the first solder mark 15 is smaller than the width of the weak portion 121 (as shown). Figure 19 (As shown).

[0090] Preferred, such as Figure 20 As shown, on the projection plane perpendicular to the length direction of the first wall 111, the orthographic projection of the first solder mark 15 and the orthographic projection of the weak part 121 are spaced apart along the thickness direction of the first wall 111. That is, the first solder mark 15 and the weak part 121 are located on different planes in the thickness direction of the first wall 111.

[0091] Specifically, in one embodiment, on a projection plane perpendicular to the first direction, the orthographic projection of the weak portion 121 at least partially coincides with the orthographic projection of the first solder mark 15 and / or the second solder mark 3. In this case, the weak portion 121 is more susceptible to heat generation from the pole assembly 13, increasing the risk of abnormal opening of the explosion-proof valve 12. Therefore, along the first direction, the minimum distance d mm between the edge of the first solder mark 15 and the second solder mark 3 closest to the weak portion 121 and the edge of the weak portion 121 satisfies 28 ≤ d ≤ 130. By further limiting the value of d, the heat transferred from the pole assembly 13 to the weak portion 121 is reduced, thereby reducing the risk of abnormal opening of the explosion-proof valve 12.

[0092] Furthermore, in one embodiment, such as Figure 8 As shown, the weak part 121 encloses and forms the opening area 123. The explosion-proof valve 12 also includes a reinforcing rib 124, which is disposed in the opening area 123. This arrangement can further improve the structural strength of the explosion-proof valve 12 and reduce the risk of abnormal valve opening.

[0093] In one embodiment, such as Figure 21 and Figure 34As shown, the current lead-out terminal 142 includes a tab 1421, which is connected to the battery cell body 141. The tab 1421 is welded to the terminal assembly 13 to form a first solder mark 15. The minimum distance d mm between the edge of the first solder mark and the edge of the weak part, which is closest to the weak part, satisfies 30≤d≤130. At this time, the tab 1421 is directly connected to the terminal assembly 13, and the impedance encountered during current transmission is small, which reduces the heat generation at the terminal assembly 13, reduces the heat of the explosion-proof valve 12, and improves the structural strength of the explosion-proof valve 12. Therefore, the value of d can be further limited, which can ensure the structural strength of the explosion-proof valve 12 while providing layout space for other components on the first wall 111.

[0094] Additionally, in another embodiment, such as Figure 11 , Figure 22 and Figure 23 As shown, the current lead-out terminal 142 includes a tab 1421 and an adapter piece 1422. The tab 1421 is connected to the cell body 141, and the tab 1421 and the adapter piece 1422 are welded together. The adapter piece 1422 is welded to the terminal assembly 13 to form a first solder mark 15. The tab 1421 includes several tab layers 14211 stacked along the thickness direction of the first wall 111, and the thickness of each tab layer 14211 is c μm, satisfying 4≤c≤18. At this time, the adapter piece 1422 is used to transfer between the tab 1421 and the terminal assembly 13. The impedance encountered during current transmission is relatively large, which affects the overcurrent capacity between the tab 1421 and the terminal assembly 13. Therefore, by limiting the value of c, the internal resistance of the tab 1421 is reduced, and the overcurrent effect is improved.

[0095] Specifically, in one embodiment, the tab layer is copper foil, and the value of c satisfies 4≤c≤12.

[0096] Specifically, in another embodiment, the tab layer is aluminum foil, and the value of c satisfies 6≤c≤18.

[0097] Optionally, c can take any value from 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or a value between any two values.

[0098] It is worth noting that for the formation of the first weld mark, the tabs and terminal blocks can be directly welded to the terminal block assembly or adapter plate, that is, several layers of tabs can be directly welded to the terminal block assembly or adapter plate. The welding method can be one or more of ultrasonic welding, laser welding, or resistance welding; alternatively, a combination of laser welding and ultrasonic welding can be used, that is, multiple layers of tabs are first ultrasonically pre-welded, and then the tabs and terminal block assembly or adapter plate are laser welded. The second weld mark can be formed using laser welding, resistance welding, ultrasonic welding, etc., with laser welding being preferred to ensure the strength and quality of the weld.

[0099] In one embodiment, the charging time for battery 1 from 10% SOC to 80% SOC is less than 20 minutes, and the minimum distance k mm between the first solder mark 15 and the second solder mark 3 satisfies 2.5 ≤ k ≤ 8. At this time, battery 1 meets the fast charging requirement, and the heat generated at the terminal assembly 13 is relatively large, which increases the heat exposure of the explosion-proof valve 12 and increases the risk of abnormal opening of the explosion-proof valve 12. Therefore, by further limiting the value of k, the overcurrent path between the first solder mark 15 and the second solder mark 3 is reduced, the overcurrent effect between the cell 14 and the conductor 2 is improved, the heat generated by the terminal assembly 13 during the charging and discharging process of battery 1 is reduced, the impact of heat on the structural strength of the explosion-proof valve 12 is reduced, and the reliability of the explosion-proof valve 12 is ensured.

[0100] It is worth noting that the charging strategy and charging time test method for "Battery 1 being charged from 10% SOC to 80% SOC" mentioned above are as follows: The prepared battery is placed at 25°C for 4 hours until thermal equilibrium is reached; the battery is charged at a constant current of 0.1C to the upper limit voltage, and then charged at a constant voltage until the current is less than or equal to 0.05C; then it is discharged at 0.1C to the lower limit voltage, and the above steps are repeated 3 times, with the capacity discharged in the third cycle as the battery discharge capacity; after standing for 10 minutes, it is discharged at 1C to 2.5V, after standing for 10 minutes, it is charged at 0.33C to 10% SOC; then it is first charged at a constant current of 4C, and then the charging rate is gradually reduced in increments of 0.2C until it drops to 0.4C, with the cutoff condition for each charge being charging to the upper limit voltage; the charging time between 10% SOC (10%×C) and 80% SOC (80%×C) is recorded. When the positive electrode active material includes lithium iron phosphate, the upper limit voltage is 3.65V; when the positive electrode active material includes lithium nickel cobalt manganese oxide, the upper limit voltage is 4.25V.

[0101] Furthermore, in one embodiment, the battery 1 is charged from 10% SOC to 80% SOC, and the maximum temperature of the terminal assembly 13 does not exceed 90°C. This setting avoids excessive heat generation at the terminal assembly 13, which would increase the risk of abnormal opening of the explosion-proof valve 12, and ensures the safe use of the battery 1.

[0102] It is worth noting that the charging strategy for "Battery 1 charging from 10% SOC to 80% SOC" and the test method for the terminal component temperature are as follows: The battery is placed at 25°C and left to stand for 4 hours until thermal equilibrium is reached; the battery is charged at a constant current of 0.1C to the upper limit voltage, and then charged at a constant voltage until the current is less than or equal to 0.05C; then discharged at 0.1C to the lower limit voltage, and the above steps are repeated 3 times, with the capacity discharged in the third cycle as the battery discharge capacity; a temperature sensor is installed at the battery terminal, left to stand for 10 minutes, discharged at 1C to 2.5V, left to stand for 10 minutes, and charged at 0.33C to 10% SOC; then it is first charged at a constant current rate of 4C, and then the charging rate is gradually reduced in 0.2C increments until it drops to 0.4C. The cutoff condition for each charge is charging to the upper limit voltage, and the highest temperature of the battery during the charging process is recorded, which is the highest temperature of the battery when it is charged from 10% SOC to 80% SOC. When the positive electrode active material includes lithium iron phosphate, the upper limit voltage is 3.65V; when the positive electrode active material includes lithium nickel cobalt manganese oxide, the upper limit voltage is 4.25V.

[0103] In one embodiment, such as Figure 31 and Figure 32 As shown, the outer casing 11 includes a housing 113 and a cover plate 114. At least one end of the housing 113 forms an opening. The cover plate 114 is welded to the housing 113 and seals the opening. The thickness of the cover plate 114 is greater than the thickness of the housing 113. The explosion-proof valve 12 and the pole assembly 13 are both disposed on the cover plate 114. That is, the cover plate 114 is the first wall 111 mentioned above. This arrangement can improve the stability and reliability of the pole assembly 13 installed on the first wall 111 (i.e., the cover plate 114), reduce the deformation of the cover plate 114 together with the pole assembly 13, and reduce the risk of cracking of the first weld mark 15 and the second weld mark 3.

[0104] Of course, in other alternative embodiments, the first wall 111 may also be the wall of the housing 113.

[0105] In one embodiment, the first wall contains titanium, with a titanium content of 70% to 99.8% by mass. That is, the outer shell is made of titanium, which has higher strength. When the electrode assembly is fixed to the titanium shell, the installation stability and reliability of the electrode assembly can be significantly improved, reducing the risk of cracking of the first and second weld marks. Therefore, the value of k / d is set to satisfy 0.021 ≤ k / d ≤ 0.38. By further limiting the value of k / d, the influence of heat from the electrode assembly on weak points is further reduced, lowering the risk of abnormal valve opening in the explosion-proof valve.

[0106] The method for testing the titanium content in the battery casing is as follows: (1) Sample preparation: First, the battery casing sample to be tested needs to be properly treated to facilitate X-ray penetration and excitation of fluorescence. The treatment methods may include cutting, grinding, polishing and other steps to ensure that the surface of the battery casing sample is flat and free of contamination.

[0107] (2) X-ray excitation: High-energy X-rays are used to irradiate the surface of the battery casing sample to excite the characteristic X-ray fluorescence of each element. The wavelength or energy characteristics of these fluorescence spectra correspond to the types of elements, thereby determining which elements are contained in the battery casing sample.

[0108] (3) Spectral collection and analysis: X-rays reflected from the surface of the battery casing sample and fluorescence spectra are collected using a spectrometer. The type and content of elements can be determined by the position and intensity of characteristic spectral lines.

[0109] (4) Matrix effect correction: Due to the interaction between various elements in the battery casing sample (matrix effect), the collected spectral data needs to be corrected to eliminate the influence of this interaction on the analysis results and improve the accuracy of the analysis.

[0110] (5) Interpretation of results: Based on the corrected data, the content of each element in the battery casing sample can be calculated, and then the mass of Ti element in the battery casing sample can be obtained as a percentage of the total mass of the battery casing sample, i.e., the mass content of Ti element.

[0111] According to an embodiment of the present invention, another aspect provides an electrical device including the battery pack 10 described above.

[0112] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0113] The preparation of the example battery and the comparative battery includes the following steps: (1) Preparation of the positive electrode: The positive electrode active material, conductive agent (e.g., acetylene black), and binder (e.g., PVDF) are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, the positive electrode sheet is obtained by rolling and slitting.

[0114] Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98): (4~1): (4~1).

[0115] (2) Preparation of negative electrode: The negative electrode active material, conductive agent (e.g., acetylene black), thickener (e.g., carboxymethyl cellulose (CMC)), and binder (e.g., styrene-butadiene rubber (SBR)) are mixed, and deionized water is added as a solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector copper foil, air-dried at room temperature, and then transferred to an oven for further drying. Finally, the negative electrode sheet is obtained by rolling and slitting.

[0116] Specifically, the ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0117] (3) Preparation of electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0118] (4) Preparation of the diaphragm: Polyethylene film is selected as the diaphragm.

[0119] (5) Preparation of lithium-ion batteries: The aforementioned positive electrode, separator, and negative electrode are sequentially wound or stacked to form a bare cell. The current lead of the bare cell is welded to the first end face of the electrode post on the first wall to form the first weld mark. The welded bare cell is then placed in the housing space. The battery is dried, injected with electrolyte, and then packaged, left to stand, formed, and calibrated to obtain a lithium-ion battery.

[0120] In addition to the above-mentioned battery material selection, this application may also select other materials, and is not limited to the materials limited by the above preparation method. The positive electrode active material can be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate; the conductive agent in the positive electrode sheet can also be selected from one or more graphite, superconducting carbon, Ketjen black, Super P, carbon nanotubes, graphene, and carbon nanofibers; the binder in the positive electrode sheet can also be selected from one or more polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene ternary copolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternary copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, and carboxymethyl chitosan; the positive electrode current collector can also be selected from one or more stainless steel, aluminum, nickel, carbon electrode, carbon, nickel, and titanium with silver plating; the positive electrode current collector can also include composite current collectors, which may include a polymer material base layer and a metal layer. Composite current collectors can be formed by forming metallic materials (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver and silver alloys, etc.) on a polymer substrate (such as a substrate of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0121] The negative electrode active material can be selected from one or more of the following negative electrode active main materials: artificial graphite, natural graphite, silicon carbide, silicon oxide, lithium titanate, etc.; the conductive agent in the negative electrode sheet can be selected from one or more of the following: conductive carbon black, conductive graphite, carbon nanotubes, graphene, carbon fiber, etc.; the binder in the negative electrode sheet can be selected from one or more of the following: styrene-butadiene rubber, polyacrylic acid and its salts, sodium alginate, etc.; the thickener in the negative electrode sheet can be selected from one or more of the following: sodium carboxymethyl cellulose, polyacrylonitrile multi-component copolymer, etc.; the negative electrode current collector can also be selected from one or more of the following: stainless steel with silver plating, stainless steel, copper, nickel, carbon electrode, carbon, nickel, titanium, etc.; the negative electrode current collector can also include composite current collectors, which can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0122] The membrane material can be selected from at least one of glass fiber, nonwoven fabric, polypropylene (PP) and polyvinylidene fluoride.

[0123] Battery pack manufacturing method Two batteries are prepared according to the above battery preparation method. The two batteries are electrically connected through a conductive busbar, and the conductive busbar is welded to the second end face of the battery terminal to form a second solder mark.

[0124] The difference between the batteries in each embodiment and the comparative battery lies in the values ​​of k and d, as shown in Table 1.

[0125] Specifically, the test method for the minimum distance k mm between the first weld mark 15 and the second weld mark 3 along the thickness direction of the first wall 111 is as follows: the distance from the first end face to the second end face of the battery terminal is measured by X-ray tomography (CT), and the average value is taken as k mm after three measurements.

[0126] Specifically, along the first direction, the test method for determining the minimum distance d mm between the edge of the first weld mark 15 and the edge of the weak part 121 closest to the weak part is as follows: use a micrometer to measure the shortest distance from the first weld mark and the orthographic projection of the first wall to the weak part, and record it as L12 mm; use a micrometer to measure the shortest distance from the second weld mark and the orthographic projection of the first wall to the weak part, and record it as L22 mm; take the minimum value between L12 and L22, which is d.

[0127] The relevant performance of the batteries in the above embodiments and comparative examples was tested, and the test results are recorded in Table 1. The test methods are as follows: Performance Test 1: Weak Point Opening Stress Test Following the battery preparation method described above, 20 battery packs were prepared for each of the embodiments and comparative examples. The k and d values ​​of the batteries in each embodiment and comparative example are shown in Table 1 below. Apart from this, the remaining structures are identical. Ten of the 20 batteries were charged to their upper limit voltage at a charging rate of 0.33C at a temperature of 25°C. The batteries in each embodiment and comparative example were subjected to a battery puncture test according to GB / T31485-2015 standard. A high-temperature resistant steel needle with a diameter of 5mm was used to penetrate the battery from a direction perpendicular to the battery's surface at a speed of 25±5mm per second, triggering thermal runaway. The pressure at the weak point of the penetrated battery in each battery pack was measured, and the average value was recorded as P1. MPa. The remaining 10 battery packs out of 20 were left to stand at 25°C for 1 hour, then charged at 0.33C to the upper limit voltage at ambient temperature of 25°C. After standing for 20 minutes, they were discharged at 0.33C to the lower limit voltage and left to stand for 20 minutes. This cycle was repeated 3 times, and the discharge capacity of the 3rd cycle was recorded as the actual capacity C1 of the battery. The batteries were then charged at 25°C at twice the actual capacity (2C1) to the upper limit voltage, left to stand for 20 minutes, then discharged at twice the actual capacity (2C1) to the lower limit voltage and left to stand for 20 minutes. This cycle of charging and discharging at twice the actual capacity (1C1) was repeated 500 times. Finally, the batteries were charged at 0.33C1 to the upper limit voltage, and the process was carried out according to GB / T31485-2015. The standard procedure involves a battery end-point puncture test using a high-temperature resistant steel needle with a diameter of 5 mm. The needle is inserted into the battery at a speed of 25 ± 5 mm per second from a direction perpendicular to the battery's surface to trigger thermal runaway. The pressure at the weak point of the punctured battery in each battery pack is measured, and the average value is recorded as P2 MPa. The pressure change rate is calculated using the formula: pressure change rate = (|P1 - P2|) / P1 × 100%. The pressure change rate at the weak point after each cycle is then considered good. If the pressure change rate is less than 5%, the result is considered good. If the pressure change rate is greater than 5% but less than 10%, the result is considered acceptable. If the pressure change rate is greater than or equal to 10%, the result is considered unacceptable.

[0128] When the positive electrode active material includes nickel-cobalt-manganese ternary materials, the upper limit voltage of the battery is 4.25V and the lower limit voltage is 2.5V. When the positive electrode active material includes lithium iron phosphate, the upper limit voltage of the battery is 3.65V and the lower limit voltage is 2.5V.

[0129] The positive electrode active material used in this test was selected from LiNi. 0.6 Co 0.2 Mn 0.2Taking O2 as an example, other positive electrode materials all meet the above test requirements. The mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2. The negative electrode active material is selected from artificial graphite. The ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2. The cell style is selected as wound cell. Other cell types all meet the above test requirements.

[0130] Performance Test 2: Solder Seal Cracking Test Following the battery preparation method described above, 100 battery packs were prepared for each embodiment and comparative example. The k and d values ​​of the batteries in each embodiment and comparative example are shown in Table 1 below. Apart from this, the remaining structures are identical. The battery packs of each embodiment and comparative example were placed in a vibration table and subjected to random vibration in the Z / Y / X directions and sinusoidal fixed-frequency vibration according to national standard GB38031-2020.8.2. After continuous random vibration for 12 hours and sinusoidal fixed-frequency vibration for 2 hours in each direction, the first and / or second solder marks were observed for cracking. If cracking occurred, the number of cracked battery packs was recorded as n. The cracking rate was calculated using the formula: cracking rate = (n / 100) × 100%. If the cracking rate was less than or equal to 2%, it was considered good; if the cracking rate was greater than 2% and less than or equal to 5%, it was considered qualified; and if it was greater than 5%, it was considered unqualified.

[0131] Table 1:

[0132] As can be seen from Table 1, in Examples 1 to 20, the value of k / d is in the range of 0.021 to 0.392. Therefore, in the battery packs of Examples 1 to 20, the test results of the weak part opening pressure test and the solder cracking test are all qualified or above, that is, there are no unqualified cases.

[0133] Furthermore, in Examples 10 to 18, the value of k / d is in the range of 0.03 to 0.257. Therefore, in the battery packs of Examples 10 to 18, the test results of the weak part opening pressure test and the solder cracking test are all good.

[0134] Furthermore, in Examples 1, 2, 7, 8, and 19, the value of k / d is in the range of 0.021 to 0.392, but not in the range of 0.03 to 0.257 and less than 0.03. Therefore, in the battery packs of Examples 1, 2, 7, 8, and 19, the cracking rate of the solder cracking test is greater than 2% and less than or equal to 5%, and the test result is qualified.

[0135] Furthermore, in Examples 3 to 6, 9 and 20, the value of k / d is in the range of 0.021 to 0.392, but not in the range of 0.03 to 0.257 and is greater than 0.257. Therefore, in the battery packs of Examples 3 to 6, 9 and 20, the pressure change rate in the weak part opening pressure test is greater than 5% and less than 10%, and the test result is qualified.

[0136] As can be seen from Table 1, in Comparative Example 3 and Comparative Example 4, the value of k / d is not in the range of 0.021 to 0.392 and is less than 0.021, which results in a cracking rate of more than 5% in the solder cracking test of the battery packs in Comparative Example 3 and Comparative Example 4, and the test results are unqualified.

[0137] As can be seen from Table 1, in Comparative Examples 1, 2 and 5, the value of k / d is not in the range of 0.021 to 0.392 and is greater than 0.392. This results in the pressure change rate of the weak part in the battery packs of Comparative Examples 1, 2 and 5 being greater than or equal to 10% during the opening pressure test, and the test result is unqualified.

[0138] The following is an explanation of the terms used in this application.

[0139] Battery packs can serve as the operating power source for electrical devices, or as the driving power source for electrical devices, replacing or partially replacing fuel or natural gas to provide driving power for vehicles. Electrical devices include: energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other technological fields.

[0140] A battery pack consists of multiple batteries, which can be connected in series, parallel, or a combination thereof. A combination thereof means that multiple batteries are connected in both series and parallel.

[0141] The battery pack is a cluster-level battery structure formed by multiple batteries connected in series, where the number of batteries in each cluster is strictly configured according to voltage and capacity requirements. Specifically, the battery unit of the battery pack includes multiple batteries, some of which are connected in series to form a cluster that meets the preset power supply voltage requirements, and at least one spare battery among the multiple batteries is bypassed.

[0142] The battery pack may include battery cells and a switching control unit.

[0143] A battery stores chemical energy and converts it into electrical energy in a controllable manner. In recyclable batteries, the active materials can be reactivated by charging after discharge, allowing for continued use. A battery includes a casing, battery cells housed within the casing, and an electrolyte.

[0144] An enclosure is a component used to provide a space to house electrode assemblies and other parts and isolate them from the external environment. An enclosure typically includes a housing with an opening at at least one end, which can be closed by a battery cover to seal and isolate the internal environment of the battery cell from the external environment.

[0145] The outer casing is made of at least one of the following materials: copper, titanium, iron, aluminum, stainless steel, and aluminum alloy.

[0146] A battery cell is the component in a battery where electrochemical reactions occur; it is the smallest unit in a battery capable of carrying out electrochemical reactions such as charging and discharging. A battery cell typically consists of a positive electrode, a negative electrode, and a separator located between the positive and negative electrodes. Battery cells can be either wound or stacked. The main shapes of battery cells are cylindrical and cuboid.

[0147] Lithium-ion cells mainly rely on the insertion and extraction of lithium ions between the positive and negative electrode plates to function.

[0148] The positive electrode is one of the core components in a battery that carries the positive electrode active material. During charging, metal ions (e.g., lithium ions) are released from the positive electrode active material (oxidation reaction), migrate through the electrolyte, and intercalate into the negative electrode. During discharging, metal ions (e.g., lithium ions in a lithium battery) are released from the negative electrode and intercalated into the positive electrode active material (reduction reaction), thus realizing the storage and release of lithium ions.

[0149] A positive electrode generally includes a positive current collector and a positive active material layer. The positive active material layer is coated on at least one surface of the positive current collector and includes: a positive active material, a conductive agent, and a binder. The positive active material includes, but is not limited to, at least one of the following: lithium phosphates, lithium transition metal oxides and their respective modified compounds, or other conventional materials that can be used as positive active materials for batteries. These positive active materials can be used alone or in combination. The lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Lithium transition metal oxides include, but are not limited to, at least one of lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt aluminum oxides, lithium nickel cobalt manganese oxides, and their modified compounds. Lithium nickel cobalt manganese oxides satisfy the general chemical formula LiNi. x Co y Mn z M fO2, where 0.1 < x < 1, 0.1 < y < 1, 0.1 < z < 1, and x + y + z + f = 1, M is a dopant element, and M includes at least one of Al, Mg, Ti, Zr, B, P, Nb, Ta, W, Zr, and V.

[0150] The positive electrode current collector includes a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The positive electrode current collector can also include a composite current collector, which may include a polymer material substrate and a metal layer. Composite current collectors are formed by forming a metal material (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0151] The positive electrode conductive agent includes, but is not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon nanotubes, graphene and carbon nanofibers.

[0152] The positive electrode binder includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0153] The negative electrode includes a negative current collector and a negative active layer disposed on at least one surface of the negative current collector. The negative current collector is a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The negative current collector may also include a composite current collector, which may include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0154] The negative electrode active layer includes the negative electrode active material, conductive components, and binders. The negative electrode active material can be carbon-based materials such as graphite, porous carbon, hard carbon, soft carbon, and mesophase carbon microspheres, or silicon-based materials such as elemental silicon, silicon oxides, silicon-carbon composites, and silicon-ammonia composites. The conductive agent can be conductive carbon black, carbon nanotubes, etc., and the binder can be styrene-butadiene rubber, polyacrylic acid, etc.

[0155] A separator is positioned between the positive and negative electrode plates to separate them and prevent short circuits. The separator can be at least one of glass fiber, non-woven fabric, polyethylene (PE), polypropylene (PP), and polyvinylidene fluoride (PVDF). A coating can also be applied to the separator surface. This coating can be inorganic or organic, wherein the inorganic coating material includes at least one of alumina, silicon dioxide, titanium dioxide, magnesium oxide, zirconium oxide, and boehmite; and the organic coating includes at least one of aramid coating and PVDF coating.

[0156] The battery cell also includes tabs, which are located on one side of the positive / negative current collector and are either separate from or integrally formed with the current collector. The tabs are electrically connected to the current collector to conduct current through it. When the tabs and current collector are separate, they can be connected by welding. The tabs are made of a highly conductive metal material (such as copper, aluminum, or nickel).

[0157] The electrolyte is located between the positive and negative electrodes, serving to conduct ions between them. Electrolytes include liquid electrolytes, gel polymer electrolytes, and solid electrolytes; among them, liquid electrolytes refer to electrolytes that are in a liquid state, possessing the function of conducting ions while isolating electrons; liquid electrolytes are composed of chemical substances such as solvents, electrolyte salts, and additives; solvents can be carbonates, carboxylic esters, or ethers, etc.; electrolyte salts can be lithium salts, sodium salts, or zinc salts; additives can be ethylene carbonate, fluoroethylene carbonate, propylene sulfite, ethylene sulfite, etc.

[0158] Terminals are used to electrically connect the battery cell located inside the casing to external devices (adjacent batteries or other electrical equipment) located outside the casing. The battery can discharge to external devices through the cell output terminals (tabs) and the external device output terminals (terminals), and an external power source can charge the battery through the terminals and tabs. Terminals can be directly electrically connected to the cell tabs, or they can be electrically connected to the tabs through metal adapters.

[0159] The electrode post is made of metal materials including but not limited to copper, aluminum, aluminum alloy, and copper-aluminum alloy.

[0160] The adapter piece has one end for electrical connection to the battery cell output terminal (tab), and the other end for electrical connection to the battery output terminal (post), allowing current to flow between the tab and post. The adapter piece is made of at least one of the following conductive metals: aluminum, aluminum alloy, or aluminum metal. The specific material of the adapter piece is selected based on the materials of the battery's posts and tabs.

[0161] An explosion-proof valve is a component or part that can be actuated to release internal pressure or temperature when the internal pressure or temperature of a battery cell reaches a predetermined threshold.

[0162] During battery use, explosion-proof valves are mainly used to prevent excessive pressure buildup inside the battery, which could cause deformation or explosion, by allowing gas to escape and reducing the internal pressure of the battery in the event of thermal runaway or other situations.

[0163] The materials used for explosion-proof valves are not limited, including but not limited to aluminum, steel, and alloys. The shape of the explosion-proof valve is not limited, such as square, oblong, elliptical, racetrack-shaped, etc. The type of explosion-proof valve is not limited, such as a notched explosion-proof valve, which can be formed by stamping or laser etching. The explosion-proof valve includes a weak point, designed to rupture when the internal pressure or temperature of the battery reaches a certain threshold, releasing the internal pressure or temperature. The weak point includes grooves, which can be formed by stamping or laser etching. The groove shape can be V-shaped, rectangular, U-shaped, trapezoidal, or multi-level grooves, etc. The grooves can be located on the inner and / or outer surfaces of the cover plate.

[0164] The explosion-proof valve and the housing can be separate structures, that is, the housing and the explosion-proof valve plate are manufactured separately and then fixed (welded) together; or an integrated explosion-proof valve can be used, that is, a weak part is made on the wall of the housing, which can be formed by mechanical cutting, laser etching or other methods.

[0165] The insulating barrier can be made of plastic, rubber, or other insulating materials. Plastics can include polyethylene terephthalate (PET), polypropylene (PP), polycarbonate (PC), polyvinyl chloride (PVC), etc., and rubber can include fluororubber, nitrile rubber, or isobutyl rubber, etc.

[0166] Busbars are used to electrically connect the terminals (current output terminals) of at least two batteries to enable series or parallel connection of multiple battery cells. Busbar materials include metals or alloys such as copper, aluminum, tungsten, and manganese.

[0167] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery pack, characterized in that, include: A battery (1) includes a casing (11), an explosion-proof valve (12), a terminal assembly (13), and a battery cell (14). The casing (11) encloses a receiving space, and the battery cell (14) is disposed within the receiving space. The casing (11) has a first wall (111). The explosion-proof valve (12) and the terminal assembly (13) are spaced apart from each other along a first direction on the first wall (111). The explosion-proof valve (12) has a weak portion (121), the thickness of which is less than the thickness of the first wall, so that the battery cell (14) can be disposed within the receiving space. When the internal pressure of the battery reaches a certain level, it breaks through the weak part to release pressure. Along the thickness direction of the first wall (111), the electrode assembly (13) has a first end face (131) close to the cell (14) and a second end face (132) away from the cell (14). The cell (14) includes a cell body (141) and a current lead-out terminal (142) electrically connected to the cell body (141). The current lead-out terminal (142) is welded to the first end face (131) to form a first solder mark (15). Conductive bus (2), at least two batteries (1) are provided, at least two batteries (1) are electrically connected through the conductive bus (2), and the conductive bus (2) is welded to the second end face (132) to form a second solder mark (3). Wherein, along the first direction, the minimum distance between the edge of the first weld (15) and the second weld (3) closest to the weak part and the edge of the weak part (121) is d mm, and along the thickness direction of the first wall (111), the minimum distance between the first weld (15) and the second weld (3) is k mm, satisfying 0.021≤k / d≤0.

392.

2. The battery pack according to claim 1, characterized in that, On the projection plane perpendicular to the thickness direction of the first wall (111), the orthographic projection of the first solder mark (15) and the orthographic projection of the second solder mark (3) are at least partially overlapped, satisfying 0.03≤k / d≤0.

392.

3. The battery pack according to claim 2, characterized in that, On the projection plane perpendicular to the thickness direction of the first wall (111), the orthographic projection of the first solder mark (15) falls within the range of the orthographic projection of the second solder mark (3), or the orthographic projection of the second solder mark (3) falls within the range of the orthographic projection of the first solder mark (15).

4. The battery pack according to claim 1, characterized in that, On the projection plane perpendicular to the thickness direction of the first wall (111), the orthographic projection of the first solder mark (15) does not coincide with the orthographic projection of the second solder mark (3).

5. The battery pack according to claim 4, characterized in that, Along the first direction, the distance between the first solder mark (15) and the second solder mark (3) is e mm, which satisfies 0.5≤e≤6.

6. The battery pack according to claim 4, characterized in that, Along the first direction, the first solder mark (15) is located closer to the weak part (121) than the second solder mark (3), and the minimum distance k mm between the first solder mark (15) and the second solder mark (3) satisfies 2.5≤k≤9.

7. The battery pack according to claim 4, characterized in that, Along the first direction, the second solder mark (3) is positioned closer to the weak part (121) than the first solder mark (15).

8. The battery pack according to claim 1, characterized in that, On the projection plane perpendicular to the thickness direction of the first wall (111), the area of ​​the orthographic projection of the first solder mark (15) is S1 mm. 2 The area of ​​the orthographic projection of the second solder mark (3) is S2 mm. 2 The condition is that S1 > S2.

9. The battery pack according to claim 8, characterized in that, The area of ​​the orthographic projection of the first solder mark (15) is S1mm. 2 The area S2 mm of the orthographic projection of the second solder mark (3) 2 The condition is satisfied that 5 ≤ S1 - S2 ≤ 150.

10. The battery pack according to claim 1, characterized in that, On the projection plane perpendicular to the thickness direction of the first wall (111), the area of ​​the orthographic projection of the first solder mark (15) is S1 mm. 2 The area of ​​the orthographic projection of the second solder mark (3) is S2 mm. 2 The condition is that S1 < S2.

11. The battery pack according to claim 1, characterized in that, The first wall (111) has a through mounting hole along its thickness direction. The electrode assembly (13) passes through the mounting hole at least partially. The first wall (111) includes a wall body (1112) and a protrusion (1113) protruding from the wall body (1112) in a direction away from the battery cell (14). The protrusion (1113) includes a fastening part (11131) and a connecting part (11132). One end of the connecting part (11132) is connected to the fastening part (11131). The other end of the connecting part (11132) is connected to the wall body (1112). The fastening part (11131) is pressed on the side of the pole assembly (13) away from the cell (14). The protrusion (1113) surrounds the mounting hole to form an inner wall surface (1111). An insulating barrier (16) is provided at least between the inner wall surface (1111) and the outer peripheral surface of the pole assembly (13). In the direction perpendicular to the thickness direction of the first wall (111), the thickness of the insulating barrier (16) is t mm, which satisfies 0.3≤t≤1.

12. The battery pack according to claim 1, characterized in that, On the projection plane perpendicular to the thickness direction of the first wall (111), the area of ​​the orthographic projection of the first solder mark (15) is S1 mm. 2 The area of ​​the orthographic projection of the first end face (131) is S3 mm. 2 The condition 0.1 ≤ S1 / S3 ≤ 0.6 is satisfied; and / or, On the projection plane perpendicular to the thickness direction of the first wall (111), the area of ​​the orthographic projection of the second solder mark (3) is S2 mm. 2 The area of ​​the orthographic projection of the second end face (132) is S4 mm. 2 The condition 0.1 ≤ S2 / S4 ≤ 0.5 is satisfied.

13. The battery pack according to claim 1, characterized in that, Two pole posts (13) are provided and their polarities are opposite. Each pole post (13) has a first solder mark (15) and a second solder mark (3). The two pole posts (13) are both provided on the first wall (111) and are spaced apart along the length direction of the first wall (111). Along the length direction of the first wall (111), the explosion-proof valve (12) is provided between the two pole posts (13).

14. The battery pack according to claim 10, characterized in that, Along the length direction of the first wall (111), the distance between the two pole post assemblies (13) is a mm, satisfying 80≤a≤270.

15. The battery pack according to claim 1, characterized in that, Two pole post assemblies (13) are provided with opposite polarities. Each pole post assembly (13) has a first solder mark (15) and a second solder mark (3). The outer shell (11) also has a second wall (112) disposed opposite to the first wall (111). One pole post assembly (13) is disposed on the first wall (111), and the other pole post assembly (13) is disposed on the second wall (112). On the projection plane perpendicular to the thickness direction of the first wall (111), the area of ​​the orthographic projection of the first solder mark (15) is S1 mm. 2 The area of ​​the orthographic projection of the second solder mark (3) is S2 mm. 2 The condition is satisfied that 30≤S1≤215 and / or 40≤S2≤200.

16. The battery pack according to any one of claims 1 to 15, characterized in that, The minimum distance d mm between the edge of the first solder mark (15) and the edge of the weak part (121) closest to the weak part satisfies 25 ≤ d ≤ 130; and / or, The minimum distance k mm between the first solder mark (15) and the second solder mark (3) satisfies 2.5≤k≤10.

17. The battery pack according to any one of claims 1 to 15, characterized in that, The weak part (121) forms a groove (122) on one side along the thickness direction of the first wall (111).

18. The battery pack according to claim 17, characterized in that, The groove (122) is a non-closed annular structure along the circumference, and a reinforcing area (125) is formed in the non-closed area. The thickness of the reinforcing area (125) is greater than the thickness of the weak part (121). Along the first direction, the reinforcing area (125) is set closer to the first solder mark (15) and the second solder mark (3) than the groove (122).

19. The battery pack according to claim 17, characterized in that, Along the thickness direction of the first wall (111), the thickness of the weak part (121) is b mm, satisfying 0.04≤b≤0.

3.

20. The battery pack according to claim 17, characterized in that, The groove (122) is located on the side of the explosion-proof valve (12) away from the battery cell (14).

21. The battery pack according to any one of claims 1 to 15, characterized in that, On a projection plane perpendicular to the first direction, at least a portion of the orthographic projection of the weak portion (121) does not coincide with the orthographic projection of the first solder mark (15).

22. The battery pack according to claim 17, characterized in that, The weak part (121) encloses and forms an opening area (123), and the explosion-proof valve (12) also includes a reinforcing rib (124), which is disposed in the opening area (123).

23. The battery pack according to any one of claims 1 to 15, characterized in that, The current lead-out terminal (142) includes a tab (1421), which is connected to the cell body (141). The tab (1421) is welded to the terminal assembly (13) to form the first solder mark (15). The minimum distance d mm between the edge of the first solder mark (15) and the edge of the weak part (121) closest to the weak part satisfies 30≤d≤130.

24. The battery pack according to any one of claims 1 to 15, characterized in that, The current lead-out terminal (142) includes a tab (1421) and an adapter plate (1422). The tab (1421) is connected to the cell body (141). The tab (1421) and the adapter plate (1422) are welded together. The adapter plate (1422) and the terminal assembly (13) are welded together to form the first solder mark (15). The tab (1421) includes several layers of tab layers (14211) stacked along the thickness direction of the first wall (111). The thickness of each layer of tab layer (14211) is c μm, satisfying 4≤c≤18.

25. The battery pack according to any one of claims 1 to 15, characterized in that, The charging time of the battery (1) from 10% SOC to 80% SOC is less than 20 minutes, and the minimum distance k mm between the first solder mark (15) and the second solder mark (3) satisfies 2.5≤k≤8.

26. The battery pack according to claim 25, characterized in that, The battery (1) is charged from 10% SOC to 80% SOC, and the maximum temperature of the terminal assembly (13) does not exceed 90°C.

27. The battery pack according to any one of claims 1 to 15, characterized in that, The outer casing (11) includes a housing (113) and a cover plate (114). At least one end of the housing (113) forms an opening. The cover plate (114) is welded to the housing (113) and seals the opening. The thickness of the cover plate (114) is greater than the thickness of the housing (113). The explosion-proof valve (12) and the pole assembly (13) are both disposed on the cover plate (114).

28. The battery pack according to any one of claims 1 to 15, characterized in that, On a projection plane perpendicular to the first direction, the orthographic projection of the weak portion (121) at least partially coincides with the orthographic projection of the first solder mark (15) and / or the second solder mark (3). Along the first direction, the minimum distance d mm between the edge of the first solder mark (15) and the edge of the weak portion (121) closest to the weak portion (121) satisfies 28≤d≤130.

29. The battery pack according to any one of claims 1 to 15, characterized in that, The first wall (111) contains titanium, and the mass content of the titanium is 70% to 99.8%, satisfying 0.021≤k / d≤0.

38.

30. An electrical device, characterized in that, The battery pack (10) includes any one of claims 1 to 29.

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