Busbar, battery module and battery pack

Abstract

The application discloses a busbar, a battery module and a battery pack. The busbar comprises at least two conductive sheets. By arranging a first weak part and a second weak part above a thinning area, when pressure relief, the thinning area will be first broken by the high-pressure gas in the single battery, the impact force will break the first weak part and the second weak part, and then the pressure relief valve can be efficiently and smoothly relieved. Moreover, when the first weak part and the second weak part are broken, the circuit connection between the adjacent two single batteries is also disconnected, thereby realizing short circuit protection, and finally realizing double protection of pressure relief protection and cell short circuit protection. In addition, the first weak part and the second weak part will also be melted due to overcurrent when subjected to strong current, and the double protection can also be achieved. The battery module with the above busbar can realize double protection of internal pressure relief protection and cell short circuit protection of the battery module. The battery pack with the above battery module has higher safety performance.

Description

TECHNICAL FIELD

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

[0002] In the field of cylindrical batteries, in order to improve the output voltage or current of the battery, a busbar is usually used to connect a plurality of single batteries in series and / or in parallel to form a battery module. The busbar can transmit the electrical energy generated by all single batteries to the output port of the battery module for use by external devices. In addition, the busbar can also evenly distribute the electrical energy difference between the single batteries, thereby improving the service life and performance of the entire battery module.

[0003] In a cylindrical battery module, the pressure relief valve of a single battery is designed on the same side as its positive and negative electrodes, and the busbar connects the positive and negative electrodes of a plurality of single batteries in series and / or in parallel through welding. This structure has a technical defect: when the pressure relief valve needs to relieve pressure, the busbar affects the pressure relief efficiency of the pressure relief valve, resulting in slow pressure relief efficiency of the pressure relief valve. When a large amount of heat is released inside the single battery, the heat inside the single battery under this structure cannot be quickly discharged, which can easily cause continuous thermal runaway reactions due to the rapid increase in heat of the surrounding single batteries, damaging the entire battery module. In addition, when a single battery itself has a short circuit, the busbar under this structure cannot provide timely and effective short circuit protection. SUMMARY

[0004] To overcome at least one of the above-mentioned defects of the prior art, one of the purposes of the present application is to provide a busbar that can improve the pressure relief efficiency of the pressure relief valve and also timely realize short circuit protection between single batteries, thereby realizing pressure relief protection and short circuit protection when the battery is abnormal.

[0005] The second purpose of the present application is to provide a battery module that can improve the efficient pressure relief of the pressure relief valve on the single battery and also timely realize short circuit protection between single batteries, thereby realizing double protection of the battery module.

[0006] The third purpose of the present application is to provide a battery pack that can ensure efficient pressure relief of the pressure relief valve on the single battery and also timely ensure short circuit protection between single batteries, thereby realizing double protection of the battery.

[0007] One of the technical solutions adopted by the present application to solve the problems is:

[0008] A busbar for connecting a plurality of single batteries in series and / or in parallel, comprising at least two conductive sheets, each conductive sheet comprising a positive electrode welding portion and a negative electrode welding portion.

[0009] The first weak part is arranged at the connection position of the positive electrode welding part of two adjacent conductive sheets, and the second weak part is arranged at the connection position of the positive electrode welding part and the negative electrode welding part in each conductive sheet.

[0010] The positive electrode welding part of each conductive sheet is connected with the positive electrode of the single battery, and the negative electrode welding part is connected with the negative electrode of an adjacent single battery.

[0011] The positive electrode of each single battery is provided with a pressure relief valve, and the positive electrode and the pressure relief valve are integrated structures. The pressure relief valve is provided with a thinned area which is opened when pressure relief is needed. The first weak part and the second weak part are respectively arranged above the thinned area. The first weak part and the second weak part are broken when the thinned area is opened, and / or the first weak part and the second weak part are melted when strong current is applied.

[0012] By arranging the first weak part and the second weak part of the busbar above the thinned area, when the pressure relief valve is opened, the thinned area is first opened by the high-pressure gas in the single battery, and the strong impact force of the rapidly opened pressure relief valve will break the first weak part and the second weak part, so that the pressure relief valve can be efficiently opened, and the busbar will not affect the opening of the pressure relief valve. At the same time, the first weak part and the second weak part are disconnected, so that the circuit connection loop between the adjacent two single batteries is also disconnected, so that the short circuit protection between the single batteries can be performed in time, and the internal pressure relief protection and the cell short circuit protection between the single batteries are simultaneously realized when the single battery is abnormal, so as to provide enhanced protection for the thermal safety and electrical safety operation of the battery. In addition, the first weak part and the second weak part will also be melted when strong current is applied, which also achieves the purpose of double protection, and realizes the internal pressure relief protection and the cell short circuit protection between the single batteries when the single battery is abnormal.

[0013] Further, the positive electrode welding part and the negative electrode welding part of each conductive sheet are respectively connected with the positive electrode and the negative electrode of the adjacent two single batteries, so that the adjacent two single batteries are connected in series to form a battery unit. The positive electrode welding parts of the two conductive sheets on the adjacent two battery units are connected to realize the parallel connection of the adjacent two battery units. The first connecting strip is arranged at the connection position of the positive electrode welding parts of the two conductive sheets on the adjacent two battery units.

[0014] In order to ensure the connection strength between the adjacent two conductive sheets and facilitate the transportation and installation of the busbar, the first connecting strip is arranged between the positive electrode welding parts of the adjacent two conductive sheets. The first connecting strip can also carry large current and reduce power loss.

[0015] Further, the first weak part is provided with two, two first weak parts are respectively arranged at two ends of the first connecting strip and close to the corresponding positive electrode welding part, and two first weak parts respectively face the thinning area of two adjacent pressure relief valves.

[0016] The technical scheme adopts two first weak parts, and two first weak parts respectively face the thinning area of two adjacent pressure relief valves, so that the connection of two adjacent conductive sheets can be independently broken when any one pressure relief valve is opened, thereby ensuring efficient pressure relief of the pressure relief valve and realizing circuit short circuit protection.

[0017] Further, the first weak part is a connecting sheet provided with a first notch.

[0018] Further, the first notch is located in the middle of the connecting sheet.

[0019] Further, the connecting sheet forms a breakable part on both sides of the first notch, and the sum of the cross-sectional areas of two breakable parts is not greater than the cross-sectional area of the first notch.

[0020] Further, the width of the breakable part is a, the width of the connecting sheet is b, and the ratio of a / b is 0.12-0.15.

[0021] The first notch of the technical scheme reduces the cross section of the connecting sheet, so that the first weak part can be broken by the opened pressure relief valve, and when the first notch is located in the middle of the connecting sheet, the first notch is a through hole, the connecting sheet forms a breakable part on both sides of the first notch, and the cross section of the breakable part is much smaller than the cross-sectional area of the first notch, so that the first weak part is more easily broken by the opened pressure relief valve.

[0022] Further, in a single conductive sheet, the positive electrode welding part and the negative electrode welding part are connected by a second connecting strip, the second weak part is arranged in the second connecting strip, and the second weak part is close to the positive electrode welding part.

[0023] The technical scheme sets the second connecting strip to enhance the connection strength of the positive electrode welding part and the negative electrode welding part in each conductive sheet, and when the battery is subjected to self-expansion force or external impact, the second connecting strip can deform correspondingly to avoid the second weak part from being disconnected.

[0024] Further, the second weak part is a connecting sheet provided with a second notch.

[0025] Further, the second notch is located in the middle of the connecting sheet, the connecting sheet forms a breakable part on both sides of the second notch, and the cross-sectional area of the breakable part is much smaller than the cross-sectional area of the second notch.

[0026] Further, the width of the breakable part is a, the width of the connecting piece is b, and the ratio of a / b is 0.073-0.077.

[0027] The second gap of the technical solution reduces the cross section of the connecting piece. When the second gap is located in the middle of the connecting piece, the second gap is a through hole, the breakable part is formed on both sides of the second gap, and the cross section of the breakable part is much smaller than the cross section of the second gap, so that the second weak part is more easily broken by the pressure relief valve.

[0028] Further, the second connecting piece strip is provided with a buffer step, the positive electrode welding part and the second weak part are located on the upper step surface of the buffer step, and the negative electrode welding part is located on the lower step surface of the buffer step, and the upper step surface is connected with the lower step surface through an inclined surface.

[0029] The buffer step of the technical solution can match the height difference between the positive electrode and the negative electrode, so that the positive electrode welding part can be attached to the upper surface of the positive electrode, and the negative electrode welding part can be attached to the upper surface of the negative electrode. Secondly, it can provide buffer for the slight relative movement between the two adjacent single batteries, avoiding the deformation or fracture of the second weak part.

[0030] Further, the height difference between the upper step surface and the lower step surface is 1-2mm.

[0031] Further, the negative electrode of the single battery is an annular surface, and the negative electrode welding part is provided with an inner concave arc surface matched with the annular surface; the positive electrode of the single battery is a circular pole, and the positive electrode welding part is a circular surface matched with the circular pole.

[0032] The negative electrode welding part of the technical solution is provided with an inner concave arc surface, which can increase the welding area with the negative electrode and enhance the connection strength, and can avoid the pressure relief valve and avoid covering the thinning area of the pressure relief valve by the negative electrode welding part, thereby causing the pressure relief valve to be unable to normally open. The circular surface of the positive electrode welding part is matched with the circular pole of the positive electrode to enhance the connection strength.

[0033] Further, the positive electrode welding part is provided with a positioning through hole for welding connection with the positive electrode of the single battery.

[0034] The positioning through hole of the technical solution is beneficial to finding the positive electrode when laser welding the positive electrode welding part and the positive electrode, thereby realizing the accuracy of welding.

[0035] Further, the pressure relief valve is arranged around the four sides of the positive electrode, and when pressure relief, the positive electrode falls off with the pressure relief valve.

[0036] Further, the negative electrode of the single battery is arranged around the four sides of the pressure relief valve, and the thinning area is arranged close to the negative electrode.

[0037] The third technical scheme adopted by the present application to solve the problems is:

[0038] The battery module comprises a plurality of single batteries and the busbar.

[0039] Further, the positive electrode welding part and the negative electrode welding part of the conductive sheet correspond to the positive electrode and the negative electrode of the adjacent two single batteries respectively, so that the adjacent two single batteries are connected in series and form a battery unit; the adjacent two battery units are connected through the positive electrode welding parts of the adjacent two conductive sheets, realizing the parallel connection of the adjacent two battery units.

[0040] Further, the second notch is a glue leakage hole, and the adjacent two single batteries are bonded together by injecting viscous glue from the glue leakage hole.

[0041] The third technical scheme adopted by the present application to solve the problems is:

[0042] The battery pack comprises the battery module.

[0043] The busbar provided by the present application has the following technical effects:

[0044] By corresponding the first weak part and the second weak part of the busbar to the upper side of the thinning area, when the pressure relief valve is relieved, the thinning area will be first punched open by the high-pressure gas in the single battery, and the strong impact force of the rapidly opened pressure relief valve will break the first weak part and the second weak part, thereby enabling the pressure relief valve to be efficiently relieved without being affected by the busbar. At the same time that the first weak part and the second weak part are broken, the circuit connection loop between the adjacent two single batteries is also disconnected, so that even if a short circuit occurs between the single batteries, short circuit protection can be performed in time, and finally the double protection of internal pressure relief protection and cell short circuit protection when the single battery is abnormal is realized synchronously, thereby providing enhanced protection for the thermal safety and electrical safety operation of the battery. In addition, the first weak part and the second weak part will also be melted when subjected to a strong current, which also achieves the purpose of double protection, realizing the internal pressure relief protection when the single battery is abnormal and the cell short circuit protection between the single batteries.

[0045] The battery module provided by the application has the busbar, the first weak part and the second weak part of the busbar are arranged opposite the thinning area, the pressure relief valve can efficiently release pressure, and the circuit connection loop between two adjacent single batteries can be disconnected, so that short circuit protection can be performed in time even if a short circuit phenomenon occurs between the single batteries or in the battery module, and finally the double protection of internal pressure relief protection and cell short circuit protection of the battery module is realized synchronously, the thermal safety and electrical safety operation performance of the battery module are improved, and the first weak part and the second weak part can also be fused due to overcurrent when strong current is received, so that the double protection of pressure relief protection and short circuit protection is also achieved.

[0046] The battery pack provided by the application has the battery module, the pressure relief valve can efficiently release pressure, and the circuit connection loop between two adjacent single batteries can be disconnected, so that short circuit protection can be performed in time even if a short circuit phenomenon occurs between the single batteries or in the battery module or the battery pack, and finally the double protection of internal pressure relief protection and cell short circuit protection of the battery pack is realized synchronously, the thermal safety and electrical safety operation performance of the battery pack are improved, and the first weak part and the second weak part can also be fused due to overcurrent when strong current is received, so that the double protection of pressure relief protection and short circuit protection is also achieved. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 It is a schematic view of the front structure of the busbar of the application;

[0048] Figure 2 It is a schematic view of the three-dimensional structure of the busbar of the application;

[0049] Figure 3 It is Figure 2 It is a schematic view of the local enlarged structure at A in the middle;

[0050] Figure 4 It is a schematic view of the front structure when the first weak part and the second weak part of the busbar of the application are disconnected;

[0051] Figure 5 It is a schematic view of the three-dimensional structure when the first weak part and the second weak part of the busbar of the application are disconnected;

[0052] Figure 6 It is a schematic view of the structure of the single battery of the application;

[0053] Figure 7 It is a schematic view of the front structure of the busbar in which a plurality of single batteries are connected in series and in parallel;

[0054] Figure 8 It is a schematic view of the three-dimensional structure of the busbar in which a plurality of single batteries are connected in series and in parallel;

[0055] Figure 9 Fig. 1 is a schematic diagram of a front view of a battery module according to the present application;

[0056] Figure 10 Fig. 2 is a schematic diagram of a perspective view of a battery module according to the present application.

[0057] In the drawings, the following reference numerals are used:

[0058] 1, single battery, 11, positive electrode, 12, negative electrode, 13, pressure relief valve, 131, thinning area;

[0059] 2, conductive sheet, 21, positive electrode welding part, 210, positioning through hole, 22, negative electrode welding part, 220, arc surface;

[0060] 23, first connecting strip, 230, first weak part, 2301, first notch, 2302, first breakable part;

[0061] 24, second connecting strip, 240, second weak part, 2401, second notch, 2402, second breakable part,

[0062] 25, buffer step, 250, upper step surface, 251, lower step surface, 252, inclined surface;

[0063] 26, processing positioning hole. DETAILED DESCRIPTION

[0064] In order to better understand and implement, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application.

[0065] In the description of the present application, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the present application.

[0066] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing the specific embodiments and are not intended to limit the present application.

[0067] Reference is made to Figure 1 and Figure 2The application discloses a busbar which is used for connecting a plurality of single batteries 1 in series and / or in parallel, so as to connect a plurality of single batteries 1 in series and / or in parallel into a battery module, as shown in Figure 7 and Figure 8 The busbar can transmit the electric energy generated by all the single batteries 1 to an output port of the battery module for use by external equipment.

[0068] In the embodiment, as shown in Figure 6 The single battery 1 is a cylindrical power battery, and the single battery 1 is provided with a positive electrode 11, a negative electrode 12 and a pressure relief valve 13, and the positive electrode 11, the negative electrode 12 and the pressure relief valve 13 on the single battery 1 are located on the same end surface of the single battery 1, so as to facilitate the busbar to connect a plurality of single batteries 1 in series and / or in parallel. Specifically, the positive electrode 11 of the single battery 1 is a positive electrode column, the pressure relief valve 13 is arranged around the periphery of the positive electrode 11, the negative electrode 12 is arranged around the periphery of the pressure relief valve 13, and the positive electrode 11, the negative electrode 12 and the pressure relief valve 13 of the single battery 1 are coaxially arranged. Since the positive electrode 11 of the single battery 1 is a positive electrode column, the upper surface of the positive electrode column is higher than the upper surfaces of the negative electrode 12 and the pressure relief valve 13 of the single battery 1, and the height difference facilitates the busbar to be connected to the positive electrode column and the negative electrode 12 respectively, and does not easily cause the positive and negative electrodes in the single battery 1 to be short-circuited. In some embodiments, the single battery 1 can also be a square battery or a rectangular battery or other shaped batteries, and the shape of the single battery 1 is not limited; when the single battery 1 can also be a square battery or a rectangular battery, the pressure relief valve 13 can be arranged on the positive electrode 11, and is not limited by the position of the negative electrode 12. In some embodiments, the pressure relief valve 13 can be a safety valve, a pressure release valve or an explosion-proof valve or other pressure relief devices.

[0069] As shown in Figure 6As shown, the positive electrode 11 of the single battery 1 and the pressure relief valve 13 are designed together, and the positive electrode 11 of the single battery 1 and the pressure relief valve 13 can be assembled in an integrated structure or integrally formed. When the pressure relief valve 13 is opened for pressure relief, the pressure relief valve 13 is detached from the single battery 1, and the positive electrode 11 is detached with the detachment of the pressure relief valve 13. When the internal pressure of the single battery 1 reaches the maximum pressure at which the pressure relief valve 13 is opened, in order to enable the pressure relief valve 13 to be smoothly opened, the pressure relief valve 13 is provided with a thinned area 131 for explosion when pressure relief, and the thinned area 131 is annularly arranged and is arranged close to the negative electrode 12 to maximize the opening area of the pressure relief valve 13, facilitating rapid pressure relief and improving safety performance. Among them, the thinned area 131 is a pressure relief notch of the pressure relief valve 13, which is a predetermined weak area that will break when reaching or exceeding a predetermined pressure; the pressure relief notch can be a groove, a notch, a weakening line or other forms of structure, and the depth, width and shape of the pressure relief notch can be set according to the actual situation, as long as it can break at the predetermined pressure. In some embodiments, when the pressure relief valve 13 is opened for pressure relief, the positive electrode 11 can also not be detached from the single battery 1, at this time, the pressure relief valve 13 needs to additionally add a circle of thinned area 131, and the added thinned area 131 needs to be close to the positive electrode 11, so that when the pressure relief valve 13 is opened for pressure relief, the two thinned areas 131 of the pressure relief valve 13 are exploded.

[0070] Designing the pressure relief valve 13 of the single battery 1 directly with the positive electrode 11 of the single battery 1, on the one hand, can ensure that when the internal pressure of the single battery 1 abnormally rises, the pressure relief valve 13 can respond quickly and accurately, and such real-time response capability helps to release the gas accumulated in the single battery 1 in time, preventing the single battery 1 from being dangerous due to excessive pressure; on the other hand, since the positive electrode 11 is one of the main areas of heat generation inside the single battery 1, designing the pressure relief valve 13 at the positive electrode 11 of the single battery 1 can more effectively utilize the heat dissipation performance of the pressure relief valve 13, helping to reduce the battery temperature and improve the thermal stability of the battery; the third aspect is that the integration of the pressure relief valve 13 and the positive electrode 11 of the battery can save the space inside the battery, making the battery structure more compact, which helps to improve the energy density and power density of the battery, while reducing the production cost. The fourth aspect is that by designing the pressure relief valve 13 together with the positive electrode 11 of the battery, the manufacturing process of the battery can be simplified, and the production difficulty can be reduced. Therefore, by designing the pressure relief valve 13 of the single battery 1 directly with the positive electrode 11 of the single battery 1, not only the safety performance and stability of the battery can be improved, but also the purposes of compact battery structure and simplified manufacturing process can be achieved.

[0071] Referring to Figure 1 and Figure 2The busbar of the application comprises at least two conductive sheets 2, each of which comprises a positive electrode welding portion 21 and a negative electrode welding portion 22, and a first weak portion 230 is arranged at the connection position of the positive electrode welding portions 21 of the two adjacent conductive sheets 2, and a second weak portion 240 is arranged at the connection position of the positive electrode welding portion 21 and the negative electrode welding portion 22 of each conductive sheet 2. Figure 8 As shown in FIG. 7 and FIG. 8, in each conductive sheet 2, the positive electrode welding portion 21 is connected with the positive electrode 11 of one single battery 1, and the negative electrode welding portion 22 is connected with the negative electrode 12 of the adjacent single battery 1, so as to realize the series connection of the two adjacent single batteries 1; the positive electrode welding portions 21 of the two adjacent conductive sheets 2 are respectively connected with the positive electrodes 11 of the two adjacent single batteries 1, so as to realize the parallel connection of the two adjacent single batteries 1. That is, each conductive sheet 2 realizes the series connection of the two adjacent single batteries 1 and forms a battery unit, the two adjacent battery units are connected through the positive electrode welding portions 21 of the two adjacent conductive sheets 2 to realize the parallel connection of the two adjacent battery units; the two adjacent battery units are arranged staggeredly, so that the single batteries 1 are arranged more compactly, so that more single batteries 1 can be arranged in a unit volume, thereby forming a battery module or a battery pack with small volume and large capacity. Specifically, the connection of the positive electrode welding portion 21 and the positive electrode 11 and the connection of the negative electrode welding portion 22 and the negative electrode 12 can be laser welding, or can be connected by pressure connection or screw connection.

[0072] When the positive electrode 11 of the single battery 1 and the pressure relief valve 13 are designed together, the busbar will hinder the opening of the pressure relief valve 13 when the busbar is welded with the positive electrode 11 of the single battery 1. The existing design has a busbar avoiding gap to avoid the position of the pressure relief valve, but in this way, the area left for the pressure relief valve on the battery end face is very limited, resulting in a small opening of the pressure relief valve, which is not fast enough for pressure relief, and the setting of the avoiding gap also reduces the connection area of the busbar and the positive electrode, thereby reducing the connection strength. Therefore, in the application, when the positive electrode 11 of the single battery 1 and the pressure relief valve 13 are designed together, the first weak portion 230 and the second weak portion 240 are arranged opposite to the thinned area 131, as shown in FIG. 9 and FIG. 10, so that when the pressure relief valve 13 is relieved, the pressure relief valve 13 can break the first weak portion 230 and the second weak portion 240, thereby ensuring that the pressure relief valve 13 can efficiently relieve pressure without being affected by the busbar. Figure 7 Figure 8 When the pressure relief valve 13 is relieved, the thinned area 131 will be first broken by the high-pressure gas in the single battery 1, and at the same time, the impact force of the rapid opening of the pressure relief valve 13 will break the first weak portion 230 and the second weak portion 240.

[0073] Figure 4 Figure 5 Figure 9 ​​​​and Figure 10 As shown in FIG. 6, the first weak part 230 and the second weak part 240 are disconnected at the same time, which disconnects the circuit connection loop between the two adjacent single batteries 1, so that the short circuit protection of the single battery 1 can be performed in time, and the double protection of the internal pressure relief protection and the cell short circuit protection of the single battery 1 in abnormal condition is realized synchronously, which provides enhanced protection for the thermal safety and electrical safety operation of the battery. In addition, the first weak part 230 and the second weak part 240 will also be melted due to overcurrent when subjected to strong current, which can also achieve the purpose of double protection, realizing the internal pressure relief protection and the cell short circuit protection between the single batteries 1 in abnormal condition. Figure 9 and Figure 10 As shown in FIG. 6, the first weak part 230 and the second weak part 240 are disconnected at the same time, which disconnects the circuit connection loop between the two adjacent single batteries 1, so that the short circuit protection of the single battery 1 can be performed in time, and the double protection of the internal pressure relief protection and the cell short circuit protection of the single battery 1 in abnormal condition is realized synchronously, which provides enhanced protection for the thermal safety and electrical safety operation of the battery. In addition, the first weak part 230 and the second weak part 240 will also be melted due to overcurrent when subjected to strong current, which can also achieve the purpose of double protection, realizing the internal pressure relief protection and the cell short circuit protection between the single batteries 1 in abnormal condition.

[0074] For the case that the first weak part 230 and the second weak part 240 are melted due to overcurrent when subjected to strong current, there are two melting conditions. The first melting condition is that the first weak part 230 realizes parallel connection of the two single batteries 1, when the internal circuit of the single battery 1 is short-circuited or thermal runaway occurs, or when external short circuit or collision of the single battery 1 occurs, the first weak part 230 will be melted to cut off the short circuit from spreading to the parallel single battery 1, avoiding the thermal runaway from spreading to the adjacent single battery 1. The second melting condition is that the second weak part 240 realizes series connection of the two single batteries 1, when the battery module composed of the single batteries 1 is externally short-circuited or internally short-circuited due to collision, the second weak part 240 will be melted to cut off the short circuit from spreading to the series single battery 1, avoiding the thermal runaway from spreading to the adjacent single battery 1.

[0075] When the battery is abnormal, for example, subjected to external collision, the internal circuit short circuit and the battery internal thermal runaway will occur synchronously, so the double protection of the internal pressure relief protection and the cell short circuit protection realized synchronously in the present application can effectively enhance the safe operation of the battery. In addition, the short circuit protection of the circuit is realized by the melted first weak part 230 and the second weak part 240 by the pressure relief valve 13, which is faster and consumes less time than the short circuit protection realized by melting, so the safety is higher.

[0076] In the present embodiment, referring to FIG. 6, Figure 9 and Figure 10As shown, since the positive electrode 11 of the single battery 1 and the pressure relief valve 13 are in an integrated structure, and the pressure relief valve 13 is arranged around the positive electrode 11, the thinning area 131 of the pressure relief valve 13 is close to the negative electrode 12. After the pressure relief valve 13 is opened, the first weak part 230 and the second weak part 240 are broken, so that the pressure relief valve 13 and the positive electrode 11 are separated from the single battery 1, and the opening of the pressure relief valve 13 is further increased, so that the single battery 1 is quickly and timely relieved.

[0077] In some embodiments, if the pressure relief valve 13 does not normally open or does not need to open or the pressure relief valve 13 opens with small pressure, that is, the first weak part 230 and the second weak part 240 are not broken, when the battery circuit is short-circuited, the first weak part 230 and the second weak part 240 can also be fused by the overload of the large current, thereby providing short-circuit protection between the single batteries 1 and preventing the spread of thermal runaway.

[0078] In this embodiment, referring to Figure 1 and Figure 2 As shown, the first weak part 230 is provided with two, and the two first weak parts 230 are respectively close to the positive electrode welding part 21 of the adjacent two conductive sheets 2, and the two first weak parts 230 are respectively opposite to the thinning area 131 of the adjacent two pressure relief valves 13. The application adopts two first weak parts 230, and the two first weak parts 230 are respectively opposite to the thinning area 131 of the adjacent two pressure relief valves 13, so that the connection of the adjacent two conductive sheets 2 can be independently broken when any one of the pressure relief valves 13 is opened, so that the pressure relief valve 13 on each single battery 1 can be smoothly opened to achieve efficient pressure relief, and short-circuit protection on any single battery 1 can also be achieved; The setting of the two first weak parts 230 can break the first weak part 230 and the second weak part 240 on the corresponding conductive sheet 2 when any one of the adjacent pressure relief valves 13 is opened, so that the connection of the adjacent two conductive sheets 2 can be independently broken, and each conductive sheet 2 can be separated from the end of the single battery 1 with the corresponding pressure relief valve 13 and the positive electrode 11. In some embodiments, the first weak part 230 can also be provided with one, as long as the first weak part 230 corresponding to the thinning area 131 of the pressure relief valve 13 is easily broken by the pressure relief valve 13, but the first weak part 230 is provided with one, which can cause the connection strength of the positive electrode welding part 21 of the adjacent two conductive sheets 2 to be weakened, and the first weak part 230 can be severely deformed or even broken when the battery is subjected to external impact.

[0079] Further, in order to enhance the connection strength of the positive electrode welding portions 21 of the two adjacent conductive sheets 2, the first connecting sheet strip 23 is arranged between the positive electrode welding portions 21 of the two adjacent conductive sheets 2, and the two first weak portions 230 are arranged on the first connecting sheet strip 23 and at the two ends of the first connecting sheet strip 23 respectively. The first connecting sheet strip 23 can not only ensure the connection strength between the two adjacent conductive sheets 2, facilitate the transportation and installation of the busbar, but also bear the external impact force, avoid the breakage of the first weak portion 230, and further bear the large current and reduce the electric loss.

[0080] In the embodiment, as shown in Figure 1 and Figure 2 , the first weak portion 230 is a first connecting sheet with a first notch 2301, and the first connecting sheet is arranged at the two ends of the first connecting sheet strip 23. Preferably, the first notch 2301 is arranged at the middle of the first connecting sheet, and in this case, the first notch 2301 is a through hole. The first connecting sheet forms the first breakable portion 2302 at the two sides of the first notch 2301, and the sum of the cross-sectional areas of the two first breakable portions 2302 is not greater than the cross-sectional area of the first notch 2301.

[0081] The first notch 2301 is arranged to reduce the cross section of the first connecting sheet, so that the first weak portion 230 can be easily and quickly broken when the pressure relief valve 13 is opened. When the first notch 2301 is arranged at the middle of the first connecting sheet, the first notch 2301 is a through hole, the first connecting sheet forms the first breakable portion 2302 at the two sides of the first notch 2301, and the cross section of the first breakable portion 2302 is much smaller than the cross-sectional area of the first notch 2301. In the case that the first breakable portion 2302 can bear the rated current during the charging and discharging of the single battery 1, the width and thickness of the first breakable portion 2302 can be designed as small as possible, so that the first weak portion 230 can be easily broken by the opened pressure relief valve 13.

[0082] Furthermore, to ensure that the first fragile part 2302 can withstand the rated current during the charging and discharging of the single battery 1, while also making the first weak part 230 more susceptible to breakage by the impact force of the opened pressure relief valve 13, it is also necessary to ensure the connection strength of the first weak part 230 during installation and transportation. Therefore, this application sets the width of the first fragile part 2302 to 'a', the width of the first connecting piece to 'b', and the ratio of a / b to '0.12-0.15'. Preferred values ​​are 0.13 and 0.14. When the ratio of a / b is less than 0.12, the first weak part 230 may sometimes melt due to its inability to withstand the rated current during battery charging and discharging, or it may fail to meet the connection strength requirements, making it prone to deformation or breakage during installation and transportation. When the ratio of a / b is greater than 0.15, although the first weak part 230 can meet the requirements of the rated current and connection strength during battery charging and discharging, it will make the first weak part 230 difficult to be broken by the impact force of the opened pressure relief valve 13, or difficult to be melted in the overcurrent state, which will cause the dual protection of the first weak part 230 to fail. Therefore, the ratio of a / b needs to be set to the range of 0.12-0.15.

[0083] In this embodiment, the width of the first fragile part 2302 is 0.7mm, and its error fluctuation value is ±0.05mm, that is, the width of the first fragile part 2302 is between 0.65mm and 0.75mm; correspondingly, the width of the first connecting piece is 5mm, and its error fluctuation value is ±0.05mm, that is, the width of the first connecting piece is between 4.95mm and 5.05mm.

[0084] In this embodiment, see Figure 1 and Figure 2 As shown, in a single conductive sheet 2, its positive electrode welding portion 21 and its negative electrode welding portion 22 are connected by a second connecting strip 24. A second weak portion 240 is provided on the second connecting strip 24, and the second weak portion 240 is close to the positive electrode welding portion 21. The second connecting strip 24 in this application enhances the connection strength between the positive electrode welding portion 21 and its negative electrode welding portion 22 in each conductive sheet 2. When the battery is subjected to its own expansion force or external impact, the second connecting strip 24 can deform accordingly, thus preventing the second weak portion 240 from breaking. The second connecting strip 24 mainly realizes the series connection of two adjacent single cells 1, and needs to carry a large current; therefore, the width of the second connecting strip 24 is wider and the cross-section is larger. The first connecting strip 23 mainly realizes the parallel connection of two adjacent single cells 1, and needs to carry a smaller current; therefore, the width of the first connecting strip 23 is narrower and the cross-section is smaller. Therefore, the width of the second connecting strip 24 is set to be greater than the width of the first connecting strip 23.

[0085] Further, the second weak portion 240 is a second connecting piece with a second notch 2401, and the second notch 2401 is also used to reduce the cross-sectional area of the small second connecting piece. The second notch 2401 is located in the middle of the second connecting piece, and the second connecting piece forms a second breakable portion 2402 on both sides of the second notch 2401, and the cross-sectional area of the second breakable portion 2402 is much smaller than that of the second notch 2401.

[0086] The second notch 2401 is provided to reduce the cross-sectional area of the second connecting piece, so that the second weak portion 240 can be easily and quickly broken when the pressure relief valve 13 is opened. When the second notch 2401 is located in the middle of the second connecting piece, the second notch 2401 is a through hole, and the second connecting piece forms a second breakable portion 2402 on both sides of the second notch 2401, and the cross-sectional area of the second breakable portion 2402 is much smaller than that of the second notch 2401, so that the second weak portion 240 is more easily broken by the impact force of the opened pressure relief valve 13. In the case of ensuring that the second breakable portion 2402 can withstand the rated current during charging and discharging of the single battery 1, the width and thickness values of the second breakable portion 2402 can be designed as small as possible, so that the second weak portion 240 is more easily broken by the impact force of the opened pressure relief valve 13.

[0087] Further, to ensure that the second breakable portion 2402 can withstand the rated current during charging and discharging of the single battery 1, and that the second weak portion 240 is more easily broken by the impact force of the opened pressure relief valve 13, it is also necessary to ensure the connection strength of the second weak portion 240 during installation and transportation. Therefore, the width value of the second breakable portion 2402 is set to a, the width value of the second connecting piece is set to b, and the ratio of a / b is set to 0.073-0.077. The preferred values are 0.074, 0.075 and 0.076. When the ratio of a / b is less than 0.073, the second weak portion 240 may be fused due to the inability to withstand the rated current during charging and discharging of the battery, and may not meet the connection strength requirement, so that it is easy to deform or break during installation and transportation. When the ratio of a / b is greater than 0.077, although the second weak portion 240 can meet the requirements of the rated current during charging and discharging of the battery and the connection strength requirement, it will not be easily broken by the impact force of the opened pressure relief valve 13, or it will not be easily broken in the overcurrent state, thereby causing the double protection of the second weak portion 240 to fail. Therefore, the ratio of a / b is set to be within the range of 0.073-0.077.

[0088] In this embodiment, the width of the second fragile part 2402 is 2.1 mm, with a tolerance of ±0.05 mm, meaning the width of the second fragile part 2402 is between 2.05 mm and 2.15 mm. Correspondingly, the width of the second connecting piece is 28 mm, with a tolerance of ±0.05 mm, meaning the width of the second connecting piece is...

[0089] Between 27.95mm and 28.05mm.

[0090] When multiple individual cells 1 are connected in series and parallel together in a busbar to form a battery module, and foaming adhesive is needed to be injected between adjacent individual cells 1 to bond all individual cells 1 together, the second notch 2401 can serve as a leakage hole. Adjacent individual cells 1 are bonded together by the foaming adhesive injected through the leakage hole, and excess adhesive can also overflow from the leakage hole, ensuring the uniformity of the adhesive filling between adjacent individual cells 1. In some embodiments, the foaming adhesive can also be other adhesives.

[0091] In this embodiment, see Figure 2 and Figure 3 As shown, the second connecting strip 24 is provided with a buffer step 25. The positive electrode welding part 21 and the second weak part 240 are both located on the upper step surface 250 of the buffer step 25, and the negative electrode welding part 22 is located on the lower step surface 251 of the buffer step 25. In the vertical direction, the upper step surface 250 is located above the lower step surface 251. In a single cell 1 where the positive and negative electrodes 12 are on the same end face, there will be a certain height difference between the upper surface of the positive electrode 11 and the upper surface of the negative electrode 12. This height difference facilitates the connection of the busbar to the positive electrode post and the negative electrode 12 respectively, and does not easily lead to a short circuit in the single cell 1. In this embodiment, the upper surface of the positive electrode 11 is higher than the upper surface of the negative electrode 12, so the upper step surface 250 is located above the lower step surface 251. In addition, the upper surface of the positive electrode 11 of the single cell 1 is also higher than the upper surface of the pressure relief valve 13 of the single cell 1, so that there is a gap between the bottom surface of the second weak part 240 and the upper surface of the corresponding pressure relief valve 13. When it is necessary to inject foaming adhesive between adjacent single cells 1 for foaming, the second notch 2401 serves as a leakage hole. After the foaming adhesive is injected from the second notch 2401, it can flow into the gap between adjacent single cells 1 by means of the gap between the bottom surface of the second weak part 240 and the upper surface of the corresponding pressure relief valve 13.

[0092] The application sets the buffer step 25, which can match the height difference between the positive electrode 11 and the negative electrode 12, so that the positive electrode welding part 21 can be attached to the upper surface of the positive electrode 11, and the negative electrode welding part 22 can be attached to the upper surface of the negative electrode 12, facilitating the welding and fixing of the busbar and the positive and negative electrodes 12; secondly, it can provide a buffer for the slight relative movement between the two adjacent single batteries 1, avoiding the deformation or breakage of the second weak part 240.

[0093] Further, the upper step surface 250 and the lower step surface 251 are connected by the inclined surface 252, and the connection between the upper step surface 250, the lower step surface 251 and the inclined surface 252 is arc-shaped. The arc shape and the inclined surface 252 both provide a larger buffer deformation for the buffer step 25, thereby enabling it to withstand a larger impact force or relative displacement. The height difference between the upper step surface 250 and the lower step surface 251 is 1-2 mm, and preferably, the height difference is 1.5 mm.

[0094] Further, the second connecting strip 24 is provided with a machining positioning hole 26, which is located between the buffer step 25 and the second weak part 240. The machining positioning hole 26 provides positioning for the busbar during machining, so as to realize accurate machining of the busbar.

[0095] In this embodiment, as shown in Figure 6 , since the positive electrode 11, the negative electrode 12 and the pressure relief valve 13 of the single battery 1 are coaxially arranged, and the positive electrode 11 is in the middle, the pressure relief valve 13 and the negative electrode 12 are sequentially arranged outside. That is, the positive electrode 11 is a pole, and the pressure relief valve 13 and the negative electrode 12 are circular rings surrounding the pole. As shown in Figure 1 and Figure 2 , in order to cooperate with the annular surface of the negative electrode 12 and avoid the pressure relief valve 13, the negative electrode welding part 22 is provided with an inner concave arc surface 220 cooperating with the annular surface; in order to cooperate with the circular pole of the positive electrode 11, the positive electrode welding part 21 is provided with a circular surface cooperating with the upper surface of the circular pole.

[0096] The negative electrode welding part 22 of the application is provided with an inner concave arc surface 220, which can increase the welding area with the negative electrode 12 and enhance the connection strength, and can avoid the pressure relief valve 13, so as to avoid covering the thinning area 131 of the pressure relief valve 13 by the negative electrode welding part 22, thereby causing the pressure relief valve 13 to be unable to normally open. The circular surface of the positive electrode welding part 21 cooperates with the circular pole of the positive electrode 11, thereby increasing the connection area and enhancing the connection strength.

[0097] In this embodiment, as shown in Figure 1 and Figure 2The positive electrode welding part 21 is provided with a positioning through hole 210 for welding connection with the positive electrode 11 of the single battery 1. When the robot performs laser welding, the positive electrode 11 can be locked through the positioning through hole 210, so that the positive electrode welding part 21 can be accurately welded to the positive electrode 11. The positive electrode 11 is provided with a groove opposite the positioning through hole 210, for accommodating the welding liquid, so that the positive electrode 11 is more firmly connected with the positive electrode welding part 21.

[0098] The positioning through hole 210 of the technical solution is beneficial to finding the positive electrode 11 when laser welding the positive electrode welding part 21 and the positive electrode 11, thereby realizing the accuracy of welding.

[0099] The application also provides a battery module, as shown in Figures 7 to 10 The battery module includes a plurality of single batteries 1 and the bus bar described above. The bus bar connects the plurality of single batteries 1 in series and / or parallel through the plurality of conductive sheets 2, thereby forming the battery module.

[0100] The battery module of the application is arranged in that the first weak part 230 and the second weak part 240 of the bus bar are located above the thinning area 131. When the pressure relief valve 13 is used for pressure relief, the first weak part 230 and the second weak part 240 can be broken by the pressure relief valve 13, so that the pressure relief valve 13 can efficiently release pressure, and at the same time, the circuit connection loop between the adjacent two single batteries 1 can be disconnected. Therefore, even if a short circuit phenomenon occurs between the single batteries 1 or inside and outside the battery module, the short circuit protection can be performed in time, and finally, the double protection of the battery module, i.e., the pressure relief protection and the cell short circuit protection, is realized synchronously, and the thermal safety and electrical safety operation performance of the battery module are improved. In addition, the first weak part 230 and the second weak part 240 can also be melted due to overcurrent when subjected to strong current, and the double protection of the pressure relief protection and the short circuit protection can also be achieved.

[0101] Further, as shown in Figure 7 and Figure 8 The positive electrode welding part 21 of each of the adjacent two conductive sheets 2 is connected with the positive electrode 11 of the adjacent two single batteries 1, so that the adjacent two single batteries 1 are connected in parallel. The positive electrode welding part 21 and the negative electrode welding part 22 of each of the conductive sheets 2 are connected with the positive electrode 11 and the negative electrode 12 of the adjacent two single batteries 1, respectively, so that the adjacent two single batteries 1 are connected in series. That is, each of the conductive sheets 2 connects the adjacent two single batteries 1 in series to form a battery unit, and the adjacent two battery units are connected through the positive electrode welding part 21 of the adjacent two conductive sheets 2, so that the adjacent two battery units are connected in parallel. The adjacent two battery units are arranged staggered, so that the single batteries 1 are arranged more compactly, thereby maximizing the capacity of the battery module while minimizing the volume.

[0102] When the battery module is assembled, the foaming glue needs to be injected between the adjacent single batteries 1 for foaming, so that when all the single batteries 1 are bonded together by the foaming glue, the second notch 2401 can serve as a glue leakage hole, the adjacent single batteries 1 are bonded together by the foaming glue injected from the glue leakage hole, and the excess glue can also overflow from the glue leakage hole, ensuring the uniformity of the filling glue between the adjacent single batteries 1. In some embodiments, the foaming glue can also be other bonding glue.

[0103] The embodiment also provides a battery pack comprising the battery module.

[0104] The battery pack of the present application can ensure that the pressure relief valve 13 can efficiently relieve pressure by arranging the first and second weak parts 230 and 240 of the busbar opposite the thinned area 131, and when the pressure relief valve 13 is relieved, the thinned area 131 will be first blown open by the high-pressure gas in the single battery 1, and the impact force of the rapid opening of the pressure relief valve 13 will break the first and second weak parts 230 and 240, which can realize the double protection of ensuring that the pressure relief valve 13 can efficiently relieve pressure and disconnecting the circuit connection loop between the adjacent two single batteries 1, so that even if a short circuit occurs in the single battery 1 or the battery module or the battery pack, the short circuit protection can be performed in time, and finally the double protection of internal pressure relief protection and cell short circuit protection of the battery pack is realized synchronously, which improves the thermal safety and electrical safety operation performance of the battery pack. In addition, the first and second weak parts 230 and 240 will also be blown off when subjected to a strong current, which can also achieve the double protection of pressure relief protection and short circuit protection.

[0105] The battery pack of the present embodiment can be applied to various fields, for example, it can be installed on electric vehicles, electric bicycles, electric motorcycles and other electric devices, and can also be installed on mobile devices such as smart phones, and can also be installed on unmanned aerial vehicles, model aircrafts, and energy storage systems such as power grid energy storage and solar energy storage, and even industrial robots and medical devices can also be used.

[0106] The technical means disclosed in the present application scheme is not limited to the technical means disclosed in the above-mentioned embodiments, but also includes the technical solutions composed of any combination of the above technical features. It should be noted that for ordinary technical personnel in the technical field, without departing from the principle of the present application, a number of improvements and refinements can be made, and these improvements and refinements are also considered within the protection scope of the present application.

Claims

1. A battery module, characterized by: The battery includes a plurality of single batteries and busbars, the busbars connect the single batteries in series and / or in parallel through conductive sheets, each conductive sheet includes a positive electrode welding part and a negative electrode welding part, and at least two conductive sheets are provided. A first weak part is arranged at the connection between the positive electrode welding parts of two adjacent conductive sheets, and a second weak part is arranged at the connection between the positive electrode welding part and the negative electrode welding part of each conductive sheet. In each conductive sheet, the positive electrode welding part is connected with the positive electrode of the single battery, and the negative electrode welding part is connected with the negative electrode of an adjacent single battery. In each single battery, a pressure relief valve is arranged at the positive electrode, the positive electrode and the pressure relief valve are in an integrated structure, the pressure relief valve is provided with a thinned area which is broken when pressure relief, the first weak part and the second weak part are respectively located above the thinned area, the first weak part and the second weak part are broken by strong impact force when the thinned area is broken, and / or the first weak part and the second weak part are melted by overcurrent when strong current is applied. The pressure relief valve is arranged around the positive electrode, when pressure relief, the positive electrode is separated from the pressure relief valve, and the negative electrode of the single battery is arranged around the pressure relief valve.

2. The battery module of claim 1, wherein: The positive electrode welding part and the negative electrode welding part of each conductive sheet are respectively connected with the positive electrode and the negative electrode of two adjacent single batteries, so that the two adjacent single batteries are connected in series and form a battery unit, two adjacent battery units are connected through the positive electrode welding parts of two conductive sheets arranged thereon, so that the two adjacent battery units are connected in parallel, and the first connecting strip is arranged at the connection between the positive electrode welding parts of two conductive sheets arranged on two adjacent battery units.

3. The battery module of claim 2, wherein: The first weak part is provided with two first weak parts which are respectively arranged at the two ends of the first connecting strip and close to the corresponding positive electrode welding part, and the two first weak parts respectively face the thinned areas of two adjacent pressure relief valves.

4. The battery module of any one of claims 1-3, wherein: The first weak part is a connecting strip provided with a first notch.

5. The battery module of claim 4, wherein: The first notch is located in the middle of the connecting strip.

6. The battery module of claim 4, wherein: The connecting strip forms a breakable part on both sides of the first notch, and the sum of the cross-sectional areas of the two breakable parts is not greater than the cross-sectional area of the first notch.

7. The battery module of claim 6, wherein: The width of the breakable part is a, the width of the connecting strip is b, and the ratio of a / b is 0.12-0.

15.

8. The battery module of claim 1, wherein: In a single conductive sheet, the positive electrode welding part and the negative electrode welding part are connected through a second connecting strip, the second weak part is arranged on the second connecting strip, and the second weak part is close to the positive electrode welding part.

9. The battery module of claim 1 or 8, wherein: The second weak part is a connecting strip provided with a second notch.

10. The battery module of claim 9, wherein: The second notch is located in the middle of the connecting strip, the connecting strip forms a breakable part on both sides of the second notch, the cross-sectional area of the breakable part is much smaller than the cross-sectional area of the second notch, the width of the breakable part is a, the width of the connecting strip is b, and the ratio of a / b is 0.073-0.

077.

11. The battery module of claim 8, wherein: The second connecting strip is provided with a buffer step, the positive electrode welding part and the second weak part are located on the upper step surface of the buffer step, the negative electrode welding part is located on the lower step surface of the buffer step, and the upper step surface is connected with the lower step surface through an inclined surface.

12. The battery module of claim 11, wherein: The height difference between the upper step surface and the lower step surface is 1-2 mm.

13. The battery module of claim 1 or 8, wherein: The negative electrode of the single battery is a ring surface, the negative electrode welding part is provided with an inner concave arc surface matched with the ring surface; the positive electrode of the single battery is a circular pole, and the positive electrode welding part is a circular surface matched with the circular pole.

14. The battery module of any one of claims 1-3, wherein: The positive electrode welding part is provided with a positioning through hole for welding connection with the positive electrode of the single battery.

15. The battery module of claim 1, wherein: The thinning area is close to the negative electrode.

16. The battery module of claim 9, wherein: The second notch is a glue leakage hole, and two adjacent single batteries are adhered together through the viscous glue injected from the glue leakage hole.

17. A battery pack characterized by: The battery module comprises the battery module as claimed in any one of claims 1-16.

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