Battery cell connecting bar and battery module

Abstract

The invention discloses a battery cell connecting bar and a battery module, the battery cell connecting bar comprises a conducting bar and a plurality of connecting sheets, and each connecting sheet comprises a battery cell connecting part, a middle connecting part and a conducting bar connecting part which are connected in sequence; the battery cell connecting part is electrically connected with the battery cell, and the conducting bar connecting part is electrically connected with the conducting bar; the middle connecting part comprises a fusing structure; and the arrangement direction of the connecting sheets is parallel to the extension direction of the conducting bar. According to the technical scheme, in the early stage of thermal runaway of the battery cell, the thermal runaway battery cell can be cut out in time, electrical isolation is achieved, the runaway intensity of the thermal runaway battery cell is reduced, and thermal runaway spreading is avoided.

Description

A cell connector and battery module Technical Field

[0001] This invention relates to the field of battery thermal protection technology, and in particular to a cell connector and a battery module. Background Technology

[0002] Lithium-ion batteries are widely used in electronic products, new energy vehicles, and energy storage products. While bringing convenience to life, lithium-ion batteries can also cause serious safety problems under extreme conditions. For example, when lithium-ion batteries are subjected to mechanical impact, overcharge, over-discharge, or high temperatures, internal short circuits, material decomposition, and other side reactions can occur, leading to the generation of large amounts of gas, a rapid rise in temperature, and thermal runaway.

[0003] Individual batteries have low voltage and low energy, so in practical applications, multiple batteries are integrated into a battery pack by connecting them in series and / or in parallel via connectors. If one cell in the battery pack experiences thermal runaway, it can easily spread along the connectors to other cells, causing thermal runaway in surrounding cells as well. If enough heat accumulates, it may cause a fire or explosion.

[0004] Before and after a cell goes out of control, it remains connected to surrounding cells via connectors. Prior to the cell's failure, electrolyte leakage and internal short circuits cause a voltage drop, leading to charging by other cells connected in parallel. This means the failed cell is overcharged before the failure, with the charging current, related to internal resistance, reaching up to 1000A. This process exacerbates thermal runaway. Simultaneously, other cells connected in parallel experience high-current discharge, increasing their temperature. In battery modules with cells only connected in series and not in parallel, the failed cell remains electrically connected to the others, potentially causing arcing and ignition. Summary of the Invention

[0005] This invention provides a cell connection bar and a battery module that can disconnect the thermally runaway cell in the early stage of thermal runaway, achieve electrical isolation, reduce the severity of the runaway cell, and prevent the spread of thermal runaway.

[0006] In a first aspect, the present invention provides a battery cell connection bus, comprising: a conductive bus; a plurality of connecting pieces, each connecting piece including a battery cell connecting portion, an intermediate connecting portion and a conductive bus connecting portion connected in sequence; the battery cell connecting portion being electrically connected to a battery cell, and the conductive bus connecting portion being electrically connected to the conductive bus; the intermediate connecting portion including a fusible structure; and the arrangement direction of each connecting piece being parallel to the extension direction of the conductive bus.

[0007] Optionally, the fusion structure comprises an alloy material doped with nano-ceramic particles.

[0008] Optionally, in the alloy material of the fused structure, the doping concentration of the nano-ceramic particles is 1% to 5%.

[0009] Optionally, the fusion structure comprises an alloy material doped with magnesium.

[0010] Optionally, in the extending direction of the connecting piece, the distance between the edge of the fusible structure near the cell connection and the edge of the cell connection near the fusible structure is d; wherein, 0.5cm≤d≤2cm.

[0011] Optionally, the alloy material includes at least two of tin, bismuth, steel, lead, and cadmium.

[0012] Optionally, the melting point of the fusible structure is 70℃~140℃.

[0013] Optionally, the intermediate connecting portion includes a first intermediate portion, the fused structure, and a second intermediate portion connected sequentially; the widths of the first intermediate portion and the second intermediate portion are W1, and the width of the fused structure is W2; wherein, W2 < W1.

[0014] In a second aspect, the present invention provides a battery module, comprising: a plurality of battery cells, and the battery cell connection bar described in the first aspect; the battery cell connection bar is electrically connected to each of the battery cells.

[0015] Optionally, the battery module may also include a heat insulation plate located between two adjacent cells.

[0016] The technical solution provided by this invention provides a fusible structure in the middle connecting part of the connecting piece. In the early stage of thermal runaway of the battery cell, the fusible structure can melt under the heat generated by the battery cell, breaking the electrical connection between the middle connecting part and the battery cell connecting part. This allows the battery cell to be cut off in time, breaking the series and parallel connection between the thermal runaway battery cell and other battery cells electrically connected on the busbar, achieving electrical isolation, reducing the severity of the runaway of the thermal runaway battery cell, and preventing the spread of thermal runaway. Attached Figure Description

[0017] Figure 1 is a schematic diagram of a cell connection bar provided in an embodiment of the present invention; Figure 2 is a schematic diagram of a connecting piece provided in an embodiment of the present invention; Figure 3 is a schematic diagram of another connecting piece provided in an embodiment of the present invention; Figure 4 is a schematic diagram of a battery module provided in an embodiment of the present invention; Figure 5 is a schematic diagram of another battery module provided in an embodiment of the present invention; Figure 6 is a temperature curve of thermal runaway of a cell provided in the present invention. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0019] Figure 1 is a schematic diagram of a battery cell connection bar provided in an embodiment of the present invention. As shown in Figure 1, the battery cell connection bar 7 includes a conductive bar 3 and a plurality of connecting pieces 2. The connecting pieces 2 include a battery cell connection part 4, an intermediate connection part 5 and a conductive bar connection part 6 connected in sequence. The battery cell connection part 4 is used to electrically connect with the battery cell 1, and the conductive bar connection part 6 is electrically connected with the conductive bar 3. The intermediate connection part 5 includes a fusible structure 53. The arrangement direction of each connecting piece 2 is parallel to the extension direction X of the conductive bar 3.

[0020] The conductive busbar 3 includes conductive materials such as aluminum, copper, or nickel. The connecting pieces 3, except for the fusible link 53, may also include conductive materials such as aluminum or nickel. The fusible link 53 may include low-melting-point conductive materials such as bismuth-tin alloy, bismuth-indium-tin alloy, or bismuth-lead alloy, and can be configured according to actual needs. The arrangement direction of each connecting piece 2 is parallel to the extension direction X of the conductive busbar 3, and the extension direction Y of each connecting piece 2 intersects with the extension direction X of the conductive busbar 3. The conductive busbar connecting part 6 in each connecting piece 2 is electrically connected to the conductive busbar 3. The intermediate connecting part 5 and the battery cell connecting part 4 do not contact the conductive busbar 3, allowing the battery cell connecting part 4 to be electrically connected to the positive or negative terminal connecting part of the battery cell 1, thus achieving a reliable electrical connection between the battery cell 1 and the conductive busbar 3.

[0021] Specifically, the intermediate connection portion 5 is located between the busbar connection portion 6 and the cell connection portion 4, and is used to transmit electrical signals from the cell connection portion 4 to the busbar connection portion 6, or vice versa. By providing a fusible structure 53 in the intermediate connection portion 5 of the connecting piece 2, the fusible structure 53 can melt under the heat generated by the cell 1 in the early stage of thermal runaway, breaking the electrical connection path between the intermediate connection portion 5 and the cell connection portion 4, so that the cell 1 can be cut off in time, breaking the series and parallel connection relationship between the thermal runaway cell and other cells 1 electrically connected on the busbar 3, realizing electrical isolation, reducing the severity of the runaway of the thermal runaway cell, and preventing the spread of thermal runaway.

[0022] The technical solution provided by this invention provides a fusible structure in the middle connecting part of the connecting piece. In the early stage of thermal runaway of the battery cell, the fusible structure can melt under the heat generated by the battery cell, breaking the electrical connection between the middle connecting part and the battery cell connecting part. This allows the battery cell to be cut off in time, breaking the series and parallel connection between the thermal runaway battery cell and other battery cells electrically connected on the busbar, achieving electrical isolation, reducing the severity of the runaway of the thermal runaway battery cell, and preventing the spread of thermal runaway.

[0023] It should be noted that, in the early stage of thermal runaway of cell 1, the heat generated by cell 1 can melt the fuse structure 53. The material of the fuse structure 53 can be set according to actual needs. In an optional embodiment, the fuse structure 53 includes an alloy material doped with nano-ceramic particles.

[0024] The alloy materials include low-melting-point conductive materials such as bismuth-tin alloys, bismuth-indium-tin alloys, and bismuth-lead alloys. The nano-ceramic particles include alumina and silicon oxide, and can be selected according to actual needs; no specific limitations are made here.

[0025] Specifically, the nano-ceramic particles are solid particles. By doping the alloy material with solid nano-ceramic particles, when the alloy material melts, the doped nano-ceramic particles can keep the alloy material in a solid state. After cooling, the solid particles will not form continuous conductive points. In addition, the nano-ceramic particles have good insulation properties, which makes the solid particles have high resistivity after cooling, thereby improving the power-off capability of the solid particles. This prevents the cell connection part 4 from being electrically connected to the busbar connection part 6 through continuous conductive points, improves the electrical isolation reliability between the thermal runaway cell and other cells 1 connected to the busbar 3, and reduces the risk of thermal runaway propagation.

[0026] Optionally, in the alloy material of the fusion structure 53, the doping concentration of nano-ceramic particles is 1% to 5%.

[0027] Here, doping concentration represents the proportion of the concentration of nano-ceramic particles to the total concentration of nano-ceramic particles and alloy materials.

[0028] Specifically, if the doping concentration of nano-ceramic particles in the alloy material is less than 1%, the concentration is too low. After the alloy material melts, some alloy material may not be adsorbed by the nano-ceramic particles, forming a continuous conductive path. This causes the cell connection 4 and the busbar connection 6 to reconnect, resulting in low electrical isolation effectiveness. Conversely, if the doping concentration of nano-ceramic particles in the alloy material is greater than 5%, the concentration is too high. The insulating properties of the nano-ceramic particles reduce the conductivity of the fused structure 53, reducing the electrical signal transmission efficiency between the cell 1 and the busbar 3 during normal operation. Therefore, by setting the doping concentration of nano-ceramic particles in the alloy material to 1%~5%, the conductivity of the fused structure 53 is improved, and in the early stages of thermal runaway in the cell 1, the fused structure 53 can reliably disconnect after melting, improving the stability and reliability of electrical isolation.

[0029] It is understood that the above description uses an alloy material doped with nano-ceramic particles as an example of the fusion structure 53. In another optional embodiment, the fusion structure 53 includes an alloy material doped with magnesium.

[0030] Magnesium is chemically reactive and reacts rapidly with oxygen in the air to form insulating magnesium oxide.

[0031] Specifically, by doping magnesium into the alloy material, when the alloy material melts, the magnesium in the alloy material can be exposed and react with oxygen in the air to generate magnesium oxide. The magnesium oxide covers and encapsulates the alloy material, preventing the alloy material from flowing and blocking the electrical connection path between the battery cell connection part 4 and the busbar connection part 6, thereby enhancing insulation and improving electrical isolation reliability.

[0032] Optionally, the alloy material includes at least two of tin, bismuth, steel, lead, and cadmium.

[0033] Specifically, the alloy material formed by tin, bismuth, steel, lead, and cadmium has a low melting point. In the early stage of thermal runaway of cell 1, the heat generated by cell 1 can melt the alloy material formed by tin, bismuth, steel, lead, and cadmium, thereby improving the reliability of electrical isolation.

[0034] Optionally, Figure 2 is a schematic diagram of a connecting piece provided in an embodiment of the present invention. As shown in Figure 2, in the extending direction Y of the connecting piece 2, the distance between the edge of the fusible structure 53 near the cell connection part 4 and the edge of the cell connection part 4 near the fusible structure 53 is d.

[0035] Where 0.5cm≤d≤2cm.

[0036] Specifically, the cell connection part 4 is usually electrically connected to the positive or negative electrode of the cell 1 by welding or other methods. If the fusible link 53 is close to one edge of the cell connection part 4, and the distance d between the fusible link 4 and the edge of the cell connection part 4 close to the fusible link 53 is less than 0.5 cm, the high temperature generated during welding may cause the fusible link 53 to melt, breaking the electrical connection between the cell connection part 4 and the busbar connection part 6, thus preventing a reliable electrical connection between the cell 1 and the busbar 3. If the fusible link 53 is close to one edge of the cell connection part 4, and the distance d between the fusible link 53 and the edge of the cell connection part 4 close to the fusible link 53 is greater than 2 cm, the fusible link 53 is farther from the cell connection part 4. In the early stage of thermal runaway of the cell 1, the time required for the heat generated by the cell 1 to be transferred to the fusible link 53 is longer, the timeliness of the fusible link 53's response to thermal runaway decreases, and electrical isolation cannot be achieved in time. Thus, by setting the edge of the fuse structure 53 near the cell connection part 4, and the distance d between the fuse structure 53 and the edge of the cell connection part 4 near the fuse structure 53 is 0.5cm to 2cm, the conductivity reliability of the fuse structure 53 during normal operation of the cell 1 is improved, as well as the timeliness of electrical isolation in the event of thermal runaway of the cell 1.

[0037] Optionally, the melting point of the fusible structure 53 is 70℃~140℃.

[0038] Specifically, if the melting point of the fuse structure 53 is less than 70°C, it may fail to fuse properly, causing the battery cell 1 to be unable to reliably connect to the busbar 3, affecting operational stability. Conversely, if the melting point of the fuse structure 53 is greater than 140°C, it cannot promptly disconnect the electrical connection between the battery cell 1 and the busbar 3 in the early stages of thermal runaway, resulting in low timeliness of disconnection and a high risk of thermal runaway propagation. Therefore, by setting the melting point of the fuse structure 53 between 70°C and 140°C, the timeliness of the fuse structure 53 in the event of thermal runaway of the battery cell 1 is improved, thereby enhancing the reliability of electrical isolation.

[0039] Optionally, Figure 3 is a schematic diagram of another connecting piece provided in an embodiment of the present invention. As shown in Figure 3, the intermediate connecting part 5 includes a first intermediate part 51, a fusion structure 53 and a second intermediate part 52 connected in sequence; the width of the first intermediate part 51 and the second intermediate part 52 is W1, and the width of the fusion structure 53 is W2; wherein, W2 < W1.

[0040] Specifically, the materials of the first intermediate portion 51 and the second intermediate portion 52 can be the same or different. For example, both the first intermediate portion 51 and the second intermediate portion 52 are made of nickel. The material of the first intermediate portion 51 can also be the same as the material of the fusible structure 53, so that both the first intermediate portion 51 and the fusible structure 53 can be melted when thermal runaway occurs in the battery cell 1, thereby improving the reliability of electrical isolation. By setting the width W2 of the fusible structure 53 to be smaller than the width W1 of the first intermediate portion 51 or the second intermediate portion 52, the heat generated by the battery cell 1 in the early stage of thermal runaway causes the fusible structure 53 to melt quickly, improving the timeliness and reliability of electrical isolation.

[0041] Figure 4 is a schematic diagram of a battery module provided in an embodiment of the present invention. As shown in Figure 4, the battery module 100 further includes: a plurality of battery cells 1, and a battery cell connection row 7 provided in any embodiment of the present invention, wherein the battery cell connection row 7 is electrically connected to each battery cell 1.

[0042] Among them, cell 1 includes a positive electrode 11 and a negative electrode 12.

[0043] Specifically, the cell connection bus 7 includes a positive electrode conductive bus 31, a positive electrode connecting piece 21, a negative electrode conductive bus 32, and a negative electrode connecting piece 22. The positive electrode connecting piece 21 is electrically connected to the positive electrode conductive bus 31 and the positive electrode 11 of the cell 1, and the negative electrode connecting piece 22 is electrically connected to the negative electrode conductive bus 32 and the negative electrode 12 of the cell 1. Thus, by electrically connecting the positive electrode of each cell 1 to the positive electrode conductive bus 31 and the negative electrode of each cell 1 to the negative electrode conductive bus 31, the cells 1 are connected in parallel via the cell connection bus 7. The electrical connection method between each cell 1 and the cell connection bus 7 can also be other; this example only illustrates a parallel connection. Specific electrical connection methods can be set according to actual needs and are not specifically limited here.

[0044] The battery module 100 includes the cell connection row 7 provided in any embodiment of the present invention. Therefore, the battery module 100 possesses the technical features of the cell connection row 7 provided in the embodiments of the present invention, and can achieve the beneficial effects of the cell connection row 7 provided in the embodiments of the present invention. The similarities can be referred to the above description of the cell connection row 7 provided in the embodiments of the present invention, and will not be repeated here.

[0045] In an optional embodiment, FIG5 is a schematic diagram of another battery module provided by an embodiment of the present invention. As shown in FIG5, the battery module 100 further includes a heat insulation plate 8 located between two adjacent cells 1.

[0046] The material of the heat insulation board 8 includes bubble cotton or heat insulation foam, which can be set according to actual needs, and no specific limitation is made here.

[0047] Specifically, by setting a heat insulation plate 8 between two adjacent cells 1 to isolate the temperature between the two cells 1, when one of the cells 1 experiences thermal runaway, the heat insulation plate 8 can reduce the transfer rate of heat from the thermally runaway cell to the adjacent cell 1, further reducing the spread of thermal runaway.

[0048] Figure 6 is a temperature curve diagram of thermal runaway of a battery cell provided by the present invention. As shown in Figure 6, the solid black line represents the temperature curve of thermal runaway of battery cell 1 in battery module 100 provided by the present application, and the dashed black line represents the temperature curve of thermal runaway of battery cell in battery module 200 using battery cell connection bar without fuse structure 53 in the prior art. Heating film is attached to the surface of battery cell in battery module 200 and battery module 100 respectively. The heating film is controlled to heat the battery cell at a temperature rise rate of 4℃ / min~7℃ / min. When the temperature of the battery cell body rises to 130℃, the temperature of conductive bar 3 in battery module 100 rises to 110℃. At this time, fuse structure 53 melts, and thermal runaway trigger battery cell disconnects from the other two battery cells. When the temperature of thermal runaway trigger battery cell rises to 180℃, the explosion-proof valve of battery cell opens, and the voltage of thermal runaway trigger battery cell begins to decrease. When the temperature rises to 240℃, the cell's temperature rise rate is greater than 1℃ / 1s, indicating that the thermally runaway cell has entered a thermal runaway state. Throughout the process, the highest temperature of the thermally runaway cell approaches 500℃. The current in the parallel circuit was detected to be 0A throughout the entire process.

[0049] In battery module 200, the explosion-proof valve of the runaway cell opens at 170℃, and the voltage begins to drop. When the temperature of the runaway cell reaches 250℃, the temperature rise rate of the cell is >1℃ / s, indicating that the cell has entered a thermal runaway state. Furthermore, as the cell voltage begins to drop, the parallel circuit begins to detect current, and the detected current increases as the voltage of the trigger cell decreases. Approximately 3 seconds before thermal runaway occurs, the detected current reaches a maximum of about 1000A. The highest temperature of the thermally runaway cell approaches 800℃, accompanied by the rupture of the cell casing.

[0050] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A battery cell connector, characterized in that, include: A conductive busbar (3); a plurality of connecting pieces (2), each connecting piece (2) including a cell connecting part (4), an intermediate connecting part (5) and a conductive busbar connecting part (6) connected in sequence; the cell connecting part (4) is used to electrically connect with the cell (1), and the conductive busbar connecting part (6) is electrically connected with the conductive busbar (3); the intermediate connecting part (5) includes a fusible structure (53); the arrangement direction of each connecting piece (2) is parallel to the extension direction of the conductive busbar (3).

2. The cell connection bar according to claim 1, characterized in that, The fusion structure (53) comprises an alloy material doped with nano-ceramic particles.

3. The cell connection bar according to claim 2, characterized in that, In the alloy material of the fused structure (53), the doping concentration of the nano-ceramic particles is 1%~5%.

4. The cell connection bar according to claim 1, characterized in that, The fusion structure (53) comprises an alloy material doped with magnesium.

5. The cell connection bar according to claim 1, characterized in that, In the extending direction of the connecting piece (2), the distance between the side edge of the fusible structure (53) near the battery cell connection part (4) and the side edge of the battery cell connection part (4) near the fusible structure (53) is d; wherein, 0.5cm≤d≤2cm.

6. A cell connection busbar according to any one of claims 2 or 4, characterized in that, The alloy material includes at least two of tin, bismuth, steel, lead, and cadmium.

7. The cell connection bar according to claim 1, characterized in that, The melting point of the fusible structure (53) is 70℃~140℃.

8. The cell connection bar according to claim 1, characterized in that, The intermediate connecting part (5) includes a first intermediate part (51), the fused structure (53) and a second intermediate part (52) connected in sequence; the width of the first intermediate part (51) and the second intermediate part (52) is W1, and the width of the fused structure (53) is W2; wherein, W2 < W1.

9. A battery module, characterized in that, include: Multiple battery cells (1) and a battery cell connection bar (7) as described in any one of claims 1 to 8; the battery cell connection bar (7) is electrically connected to each of the battery cells (1).

10. The battery module according to claim 9, characterized in that, Also includes: A heat insulation plate (8) is located between two adjacent cells (1).

Images