Compact and lightweight thermal-runaway propagation suppression structure for lithium-ion battery module

Abstract

Provided in the present invention is a compact and lightweight thermal-runaway propagation suppression structure for a lithium-ion battery module. The structure comprises: thermal insulation sleeves, which each cover a battery cell; a high-specific-heat-capacity thermally-conductive frame, in which all battery cells and thermal insulation sleeves are embedded; thermal insulation plates, which are each placed at the top of the high-specific-heat-capacity thermally-conductive frame; and cooling measures, which are arranged on side faces of the high-specific-heat-capacity thermally-conductive frame. The overall lightweight structure in the present invention enables all the battery cells to share one heat dissipation element, thereby increasing the utilization rate of the heat dissipation element; moreover, the structure in the present invention facilitates the uniform heating of each surface of each battery cell in the module, makes full use of the thermal mass of an individual battery cell, and allows all the battery cells in the module to participate in heat sharing. In addition, the frame achieves the function of fixing the battery cells, and no additional battery-cell fixing apparatus is required for assembling the battery module. Therefore, the present invention is conducive to simplifying the structure of the module, providing a thermal-runaway propagation suppression structure with a smaller volume, and reducing the loss of energy density of the battery module caused by safety measures.

Description

A compact, lightweight structure for suppressing thermal runaway propagation in lithium-ion battery modules.

[0001] Technical Field

[0002] This invention belongs to the field of lithium-ion battery thermal safety, specifically relating to a compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure. Background Technology

[0003] In recent years, fires in new energy vehicles caused by thermal runaway of lithium-ion batteries have occurred frequently, seriously threatening the personal and property safety of users. An efficient thermal management system can effectively reduce the risk of thermal runaway in lithium-ion batteries, but under conditions of mechanical abuse, thermal abuse, and electrical abuse, the cells still have a relatively high probability of thermal runaway. While the damage caused by thermal runaway in a single cell is limited, in the absence of countermeasures, thermal runaway can easily propagate between adjacent cells, triggering cascading accidents and leading to serious fires or even explosions. Therefore, given that intrinsic safety of lithium-ion batteries is unlikely to be achieved in the short term, research on technologies to suppress the propagation of thermal runaway in lithium-ion batteries is essential.

[0004] Based on the heat dissipation of thermally runaway cells within a battery module, existing thermal runaway propagation suppression technologies can be categorized into four types: heat dissipation, heat storage, insulation, and coupling methods. Heat dissipation methods utilize traditional liquid cooling, heat pipe cooling, and spray cooling to remove heat from the module in a short time. Heat storage methods are passive, relying on heat sinks such as metal plates and phase change materials to absorb the explosive heat generated by the thermally runaway cell and mitigate thermal shock. Insulation methods utilize aerogels, epoxy resins, and other novel insulation materials to block heat transfer between the thermally runaway cell and adjacent cells. Using only heat dissipation or heat storage methods can lead to complex or bulky systems, while using only insulation methods cannot adequately address battery thermal management. Therefore, coupling heat dissipation or heat storage methods with insulation methods in a reasonable manner is a more feasible solution.

[0005] An existing battery module for delaying thermal runaway (CN117352918A) utilizes an immersed phase change material to coat the battery cell, with a ceramic fiber coating around the phase change material, and an aerogel pad between the ceramic fiber coatings of different battery cells. A lithium-ion battery module (CN105633502B) that can suppress the spread of thermal runaway consists of each sub-unit assembled sequentially from a thermally conductive sheet, a battery cell, and a thermal insulation pad. An insulating structure (CN205406679U) arranged between adjacent lithium-ion batteries to prevent the spread of thermal runaway comprises a central region made of a high thermal conductivity material and a low thermal conductivity layer covering the outer wall of the central region for contact with the battery cell.

[0006] In summary, the aforementioned technologies all employ a similar sandwich structure, providing both heat dissipation and insulation. However, this structure hinders the efficient utilization of heat dissipation resources within the overall battery module. Furthermore, due to the thermal runaway phenomenon occurring near adjacent cells in such structures, localized overheating can cause certain cells to enter thermal runaway prematurely, resulting in insufficient utilization of the battery's thermal mass. Therefore, existing thermal propagation prevention designs for lithium-ion battery modules still suffer from bulky and cumbersome structures. Summary of the Invention

[0007] To address at least one of the shortcomings of existing technologies, this invention provides a compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure. This invention utilizes a heat-insulating cylinder to encase the battery cell, embedding the heat-insulating cylinder and the battery cell together within a high specific heat capacity thermally conductive frame. When a battery cell in the battery module experiences thermal runaway, the high specific heat capacity thermally conductive frame absorbs and spatially averages the heat dissipated by the thermally runaway cell, while the heat-insulating cylinder reduces the rate at which the thermally runaway cell releases heat to the high specific heat capacity thermally conductive frame, providing time for the frame to average the heat. Furthermore, heat-insulating plates are placed on both sides of the cell's safety valve to reduce radiative heat transfer from the flames and high-temperature fumes generated by the thermally runaway cell to adjacent cells. Additionally, cooling measures are provided on the sides of the high specific heat capacity thermally conductive frame to accelerate heat dissipation.

[0008] The present invention is achieved by at least one of the following technical solutions.

[0009] A compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure includes multiple battery cells and a high specific heat capacity thermally conductive frame. The high specific heat capacity thermally conductive frame has grooves corresponding to the multiple battery cells. Each battery cell is covered with a heat insulation cylinder, and the heat insulation cylinder and the battery cell are embedded in the groove. Each heat insulation cylinder has heat insulation plates on both sides, and the heat insulation plates are located on the top of the high specific heat capacity thermally conductive frame.

[0010] Furthermore, the heat insulation cylinder is made of an electrically insulating material with a thermal conductivity of less than 0.05 W / (m·K), and the wall thickness of the heat insulation cylinder is 0.5 mm-2 mm.

[0011] Furthermore, the high specific heat capacity thermally conductive frame has a specific heat capacity greater than 2000 kJ / (m³). 3 It is made of a metal material with a thermal conductivity greater than 200 W / (m·K) and a high specific heat capacity thermal conductive frame wall thickness of 2mm-20mm.

[0012] Furthermore, the surface of the high specific heat capacity thermally conductive frame exposed to air is provided with a graphene electrically insulating sticker.

[0013] Furthermore, each battery cell includes a cell body, a positive electrode, a negative electrode, and a safety valve.

[0014] Furthermore, each heat insulation plate is located on both sides of the safety valve, and the thickness of the heat insulation plate is equal to the wall thickness of the high specific heat capacity heat-conducting frame at the corresponding location.

[0015] Furthermore, the heat insulation board is made of an electrically insulating material with a thermal conductivity of less than 0.3 W / (m·K).

[0016] Furthermore, the height of the insulation board is 20mm-100mm.

[0017] Furthermore, the electrical insulating material is epoxy resin or polyimide.

[0018] Furthermore, the outer surface of the high specific heat capacity thermally conductive frame is provided with cooling measures, which are phase change materials or liquid cooling plates.

[0019] Compared with existing technologies, the beneficial effects of the present invention are as follows:

[0020] This invention simplifies the module structure, provides a thermal runaway propagation suppression structure with a smaller volume fraction, and reduces the energy density loss of the battery module due to safety measures. This is mainly reflected in the following aspects:

[0021] (1) No additional cell fixing device is required. The high specific heat capacity thermally conductive frame in this invention can simultaneously serve to fix the cell. In addition, by connecting the proposed high specific heat capacity thermally conductive frame to the battery pack housing with bolts, it can directly replace the support beam in the battery pack.

[0022] (2) Efficient utilization of heat dissipation elements. For existing sandwich structures, when a cell in a battery module experiences thermal runaway, only the heat dissipation elements of adjacent cells can function. The thermal runaway prevention design for other cells within the module occupies a large amount of space but does not play a role, resulting in waste. The heat insulation cylinder combined with the high specific heat capacity thermally conductive frame design proposed in this invention allows all cells to share a single heat dissipation element, greatly improving the utilization rate of the heat dissipation element.

[0023] (3) Full utilization of cell thermal mass. Due to the low thermal conductivity in the direction perpendicular to the core layer, local heating will cause the local temperature of a single cell to rise rapidly. When the overall average temperature of the single cell is low, it will enter a thermal runaway state, and the thermal mass of the single cell will not be fully utilized. However, in the battery module using the proposed structure, after a cell thermally runs away, the heat insulation cylinder covering each cell allows the heat released by the thermally runaway cell to be preferentially conducted within the high specific heat capacity thermally conductive frame. After a certain period of time, the frame exhibits a relatively uniform temperature distribution, realizing uniform heating of each cell and each surface within the module. This not only makes full use of the thermal mass of the single cell itself, but also allows all cells within the module to participate in heat sharing. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0025] Figure 1 is a schematic diagram of a method for fixing the proposed battery module in a battery box according to an embodiment of the present invention;

[0026] Figure 2 is a schematic diagram of a compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure provided in an embodiment of the present invention;

[0027] Figure 3 is a schematic diagram of the battery cell structure proposed in an embodiment of the present invention;

[0028] Figure 4 shows the temperature curves of each cell surface after thermal runaway in the third cell of the battery module in Embodiment 2 of the present invention.

[0029] Figure 5 shows the temperature curves of each cell surface after thermal runaway in the third cell of the battery module in Embodiment 3 of the present invention.

[0030] In the diagram, 1-battery module, 11-cell, 111-cell body, 112-positive electrode, 113-negative electrode, 114-safety valve, 12-heat insulation cylinder, 13-high specific heat capacity thermal conductive frame, 14-heat insulation plate, 15-cooling measures, 16-connecting piece, 2-battery pack housing, 3-bolt. Embodiments of the present invention

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] A compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure includes a battery module 1 and a high specific heat capacity thermally conductive frame 13. The battery module includes multiple battery cells 11, which are welded and fixed together using aluminum alloy connecting pieces 16. The high specific heat capacity thermally conductive frame 13 has grooves corresponding to the multiple battery cells 11. Each battery cell is covered with a heat insulation cylinder 12, and the heat insulation cylinder 12 and the battery cell are embedded in the groove. Each heat insulation cylinder 12 has heat insulation plates 14 on both sides, and the heat insulation plates are located on the top of the high specific heat capacity thermally conductive frame 13.

[0034] The wall thickness of the heat insulation cylinder 12 is 0.5mm-2mm. The heat insulation cylinder 12 is made of an electrically insulating material with a thermal conductivity of less than 0.05W / (m·K).

[0035] The high specific heat capacity thermally conductive frame 13 has a specific heat capacity greater than 2000 kJ / (m³). 3 It is made of a metallic material with a thermal conductivity greater than 200 W / (m·K). The wall thickness of the high specific heat capacity thermally conductive frame is 2mm-20mm. The surface of the high specific heat capacity thermally conductive frame exposed to air is covered with a graphene electrically insulating sticker.

[0036] As shown in Figure 3, each battery cell includes a battery cell body 111, a positive electrode 112, a negative electrode 113, and a safety valve 114. Each heat insulation plate 14 is located on both sides of the safety valve 114. The thickness of the heat insulation plate is equal to the wall thickness of the high specific heat capacity heat-conducting frame at the corresponding position, and the height of the heat insulation plate is 20mm-100mm.

[0037] The heat insulation board is made of an electrically insulating material with high mechanical strength and a thermal conductivity of less than 0.3 W / (m·K), which can be epoxy resin or polyimide.

[0038] The outer surface of the high specific heat capacity thermally conductive frame is provided with cooling measures. The cooling measures are phase change materials or liquid cooling plates.

[0039] In this embodiment, the high specific heat capacity thermally conductive frame has threaded holes drilled on both end faces, and the battery module 1 is locked to the side wall of the battery pack housing 2 by bolts 3 and threaded holes, as shown in Figure 1.

[0040] Example 2

[0041] As shown in Figure 2, the present invention proposes a compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure, which includes multiple battery cells 11, a heat insulation cylinder 12 surrounding each battery cell 11, a high specific heat capacity thermally conductive frame 13 embedded with all battery cells and the heat insulation cylinder, and heat insulation plates 14 located on both sides of each battery cell 11, with the heat insulation plates 14 placed on top of the high specific heat capacity thermally conductive frame 13.

[0042] In this embodiment, the battery cell 11 has geometric dimensions of 130mm*50mm*180mm, a ternary lithium chemical system, a capacity of 50Ah, and a density of 2055.1kg / m³. 3 The specific heat capacity is 830 J / (kg·K), the thermal conductivity in the direction parallel to the core layer is 29.556 W / (m·K), and the thermal conductivity in the direction perpendicular to the core layer is 0.892 W / (m·K). The specific structure of the battery cell is shown in Figure 3. Each battery cell 11 includes a battery cell body 111, a positive electrode 112, a negative electrode 113, and a safety valve 114.

[0043] The heat insulation cylinder 12 is made of silica nano-aerogel, with a thermal conductivity of 0.018 W / (m·K) at room temperature, a thickness of 0.75 mm, and a density of 0.21 kg / m³. 3 Its specific heat capacity is 590.95 J / (kg·K).

[0044] The high specific heat capacity thermal conductive frame 13 is made of aluminum, with a thermal conductivity of 202.4 W / (m·K), a density of 0.21 kg / m³, and a specific heat capacity of 590.95 J / (kg·K). The wall thickness of the high specific heat capacity thermal conductive frame between the battery cells is 6 mm, and the wall thickness at both ends of the high specific heat capacity thermal conductive frame 13 is 7.5 mm.

[0045] The heat insulation board 14 is made of epoxy resin with a thermal conductivity of 0.15 W / (m·K). Its thickness is equal to the wall thickness of the high specific heat capacity thermally conductive frame 3 at the corresponding location, its height is 40 mm, its density is 1130 kg / m³, and its specific heat capacity is 1221 J / (kg·K). The heat insulation board 14 is placed on both sides of the battery cell safety valve 114 and fixed using epoxy AB strong adhesive. The surface of the high specific heat capacity thermally conductive frame 13 exposed to air is covered with graphene insulating paper to prevent unnecessary short circuits.

[0046] The battery module in this embodiment includes six cells 11, which are welded and fixed in series using aluminum alloy connecting pieces 16. The aluminum alloy grade is 6061, and the thickness of the connecting pieces 16 is 3mm.

[0047] As shown in Figure 4, for the battery module using the thermal runaway propagation suppression structure proposed in this invention, after the third cell (from left to right) experiences thermal runaway induced by needle puncture, the left and right sides of the affected cells within the module exhibit nearly identical temperature changes, indicating that the affected cells are uniformly heated. Specifically, the peak temperature of the second cell is 118°C, and the peak temperature of the first cell is 95°C. The results show that no thermal runaway propagation occurred within the battery module.

[0048] Example 3

[0049] As shown in Figure 2, the present invention proposes a compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure, which includes multiple battery cells 11, a heat insulation cylinder 12 surrounding each battery cell 11, a high specific heat capacity thermally conductive frame 13 embedded with all battery cells and the heat insulation cylinder, a heat insulation plate 14 located on both sides of each battery cell 11, the heat insulation plate 14 being placed on top of the high specific heat capacity thermally conductive frame 13, and cooling measures 15 on the sides of the high specific heat capacity thermally conductive frame 13.

[0050] In this embodiment, the battery cell 11 has geometric dimensions of 130mm*50mm*180mm, a ternary lithium chemical system, a capacity of 50Ah, and a density of 2055.1kg / m³. 3The specific heat capacity is 830 J / (kg·K), the thermal conductivity in the direction parallel to the core layer is 29.556 W / (m·K), and the thermal conductivity in the direction perpendicular to the core layer is 0.892 W / (m·K). The specific structure of the battery cell is shown in Figure 3. Each battery cell 11 includes a battery cell body 111, a positive electrode 112, a negative electrode 113, and a safety valve 114.

[0051] The heat insulation cylinder 12 is made of silica nano-aerogel, with a thermal conductivity of 0.018 W / (m·K) at room temperature, a thickness of 0.75 mm, and a density of 0.21 kg / m³. 3 Its specific heat capacity is 590.95 J / (kg·K).

[0052] The high specific heat capacity thermal conductive frame 13 is made of aluminum, with a thermal conductivity of 202.4 W / (m·K), a density of 0.21 kg / m³, and a specific heat capacity of 590.95 J / (kg·K). The wall thickness of the high specific heat capacity thermal conductive frame between the battery cells is 6 mm, and the wall thickness at both ends of the high specific heat capacity thermal conductive frame 13 is 7.5 mm.

[0053] The heat insulation plate 14 is made of epoxy resin with a thermal conductivity of 0.15 W / (m·K). Its thickness is equal to the wall thickness of the high specific heat capacity thermally conductive frame 13 at the corresponding location, its height is 40 mm, its density is 1130 kg / m³, and its specific heat capacity is 1221 J / (kg·K). The heat insulation plate 14 is placed on both sides of the battery cell safety valve 114 and fixed using epoxy AB strong adhesive. The surface of the high specific heat capacity thermally conductive frame 13 exposed to air is covered with graphene insulating paper to prevent unnecessary short circuits.

[0054] Cooling measure 5 involves cooling with a phase change material (PCM). The PCM used is a solid-solid PCM with a thickness of 8 mm, a phase change temperature of 42°C, a latent heat of phase change of 180,000 J / kg, a specific heat capacity of 1,800 J / (kg·K), and a density of 800 kg / m³. 3 .

[0055] The battery module in this embodiment includes six cells 11, which are welded and fixed in series using aluminum alloy connecting pieces 16. The aluminum alloy grade is 6061, and the thickness of the connecting pieces 16 is 3mm.

[0056] As shown in Figure 5, for the battery module using the thermal runaway propagation suppression structure proposed in this invention, after the third cell (from left to right) experiences thermal runaway induced by needle puncture, the left and right sides of the affected cells within the module exhibit nearly identical temperature changes, indicating that the affected cells are uniformly heated. The peak temperature of the second cell is 105°C, and the peak temperature of the first cell is 85°C. The results show that no thermal runaway propagation occurred within the battery module.

[0057] This invention provides a compact, lightweight lithium-ion battery module thermal runaway propagation suppression structure. When a cell in the battery module experiences thermal runaway, a high specific heat capacity thermally conductive frame 13 is used to absorb and spatially average the heat dissipated by the thermally runaway cell. A heat insulation cylinder 12 reduces the rate at which the thermally runaway cell releases heat to the high specific heat capacity thermally conductive frame 13, providing time for the frame to average the heat. Furthermore, heat insulation plates 14 are placed on both sides of the safety valve of the cell 11 to reduce radiative heat transfer from the flames and high-temperature fumes generated by the thermally runaway cell to adjacent cells. Additionally, cooling measures 15 are provided on the sides of the high specific heat capacity thermally conductive frame to accelerate heat dissipation.

[0058] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A compact, lightweight lithium-ion battery module thermal runaway propagation suppression structure, characterized in that, It includes multiple battery cells (11) and a high specific heat capacity thermal conductive frame (13). The high specific heat capacity thermal conductive frame (13) has grooves corresponding to the multiple battery cells (11). Each battery cell (11) is covered with a heat insulation cylinder (12). The heat insulation cylinder (12) and the battery cell (11) are embedded in the groove. Each heat insulation cylinder (12) has heat insulation plates (14) on both sides. The heat insulation plates (14) are located on the top of the high specific heat capacity thermal conductive frame (13).

2. The compact, lightweight lithium-ion battery module thermal runaway propagation suppression structure according to claim 1, characterized in that, The heat insulation cylinder (12) is made of an electrically insulating material with a thermal conductivity of less than 0.05 W / (m·K), and the wall thickness of the heat insulation cylinder (12) is 0.5 mm to 2 mm.

3. The compact, lightweight lithium-ion battery module thermal runaway propagation suppression structure according to claim 1, characterized in that, The high specific heat capacity thermally conductive frame (13) has a specific heat capacity greater than 2000 kJ / (m³). 3 The high specific heat capacity thermally conductive frame (13) is made of a metal material with a thermal conductivity greater than 200 W / (m·K) and a wall thickness of 2 mm-20 mm.

4. The compact, lightweight lithium-ion battery module thermal runaway propagation suppression structure according to claim 1, characterized in that, The high specific heat capacity thermally conductive frame (13) has a graphene electrically insulating sticker on the surface exposed to air.

5. The compact, lightweight lithium-ion battery module thermal runaway propagation suppression structure according to claim 1, characterized in that, Each cell (11) includes a cell body (111), a positive electrode (112), a negative electrode (113), and a safety valve (114).

6. The compact, lightweight lithium-ion battery module thermal runaway propagation suppression structure according to claim 5, characterized in that, Each heat insulation plate (14) is located on both sides of the safety valve (114), and the thickness of the heat insulation plate (14) is equal to the wall thickness of the high specific heat capacity heat-conducting frame (13) at the corresponding position.

7. The compact, lightweight lithium-ion battery module thermal runaway propagation suppression structure according to claim 1, characterized in that, The heat insulation board (14) is made of an electrically insulating material with a thermal conductivity of less than 0.3 W / (m·K).

8. A compact, lightweight lithium-ion battery module thermal runaway propagation suppression structure according to claim 7, characterized in that, The height of the heat insulation board (14) is 20mm-100mm.

9. A compact, lightweight lithium-ion battery module thermal runaway propagation suppression structure according to claim 7, characterized in that, The electrical insulating material is epoxy resin or polyimide.

10. A compact, lightweight lithium-ion battery module thermal runaway propagation suppression structure according to any one of claims 1 to 9, characterized in that, The outer surface of the high specific heat capacity thermally conductive frame (13) is provided with cooling measures, which are phase change materials or liquid cooling plates.

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