Compact light-weight lithium ion battery module thermal runaway propagation inhibition structure

Abstract

The invention provides a compact light-weight lithium ion battery module thermal runaway propagation inhibition structure. Comprising heat insulation cylinders wrapping the peripheries of battery cells, a high-specific-heat-capacity heat conduction frame in which all the battery cells and the heat insulation cylinders are embedded, heat insulation plates arranged at the top of the high-specific-heat-capacity heat conduction frame, and cooling measures arranged on the side faces of the high-specific-heat-capacity heat conduction frame. Meanwhile, the structure is beneficial to uniform heating of each surface of each battery cell in the module, the heat quality of the single battery cells is fully utilized, and all the battery cells in the module participate in heat sharing. In addition, the frame plays a role in fixing the battery cell, and an additional battery cell fixing device is not needed in the assembly of the battery module. Therefore, the invention is beneficial to simplifying the module structure, providing a thermal runaway propagation inhibition structure with a smaller volume ratio, and reducing the energy density loss of the battery module caused by safety measures.

Description

Technical Field

[0001] The present invention belongs to the field of thermal safety of lithium-ion batteries, and in particular relates to a compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure. Background Art

[0002] In recent years, fire accidents of 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 of lithium-ion batteries, but in cases of mechanical abuse, thermal abuse, and electrical abuse, the battery cells are still more likely to experience thermal runaway. The harm caused by thermal runaway of a single battery cell is limited, but in the absence of countermeasures, thermal runaway can easily spread between adjacent batteries, causing cascade accidents, leading to serious fires and even explosions. Therefore, under the premise that it is difficult for lithium-ion batteries to achieve intrinsic safety in the short term, it is very necessary to study the technology to suppress the propagation of thermal runaway of lithium-ion batteries.

[0003] According to the heat destination of the thermal runaway battery in the battery module, the existing thermal runaway propagation suppression technology can be divided into four categories: heat dissipation, heat storage, insulation and coupling methods. The heat dissipation method is to use traditional liquid cooling, heat pipe cooling and spray cooling to bring the heat out of the module in a short time; the heat storage method is a passive method that relies on heat sinks such as metal plates and phase change materials to absorb the explosive heat generated by the thermal runaway battery cells and alleviate thermal shock; the insulation method is to use aerogel, epoxy resin and other new insulation materials to block the heat transfer between the thermal runaway battery cells and adjacent battery cells. Using only heat dissipation or heat storage methods will make the system complex or bulky, while using only insulation methods cannot take into account battery thermal management. Therefore, coupling heat dissipation or heat storage methods with insulation methods in a reasonable way is a more feasible solution.

[0004] An existing battery module for delaying the spread of heat (CN117352918A) uses an immersed phase change material to coat the battery cell, and sets a ceramic fiber coating on the outer ring of the phase change material, and sets an aerogel pad between the ceramic fiber material coatings of different battery cells. A lithium-ion battery module that can suppress the spread of thermal runaway (CN105633502B), each subunit is assembled in sequence by a thermal conductive sheet, a battery cell and an insulating pad. An insulating structure (CN205406679U) arranged between adjacent lithium-ion batteries to prevent the spread of thermal runaway, consisting of a central area made of a high thermal conductivity material, and a low thermal conductivity layer covering the outer wall of the central area for contact with the battery cell.

[0005] In general, the above technologies all use a similar sandwich structure, which has both heat dissipation and heat insulation functions. However, this structure is not conducive to the efficient use of the heat dissipation elements of the battery module as a whole. At the same time, because the thermal runaway cells produced by similar structures are locally overheated near the cells, the cells will enter the thermal runaway state first, and the thermal mass of the battery itself cannot be fully utilized. Therefore, the existing lithium-ion battery module heat spread prevention design still has the problem of bulky and bloated structure. Summary of the invention

[0006] In order to solve at least one of the deficiencies in the prior art, the present invention provides a compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure. The present invention uses an insulation tube to cover the battery cell, and embeds the insulation tube together with the battery cell into a high specific heat capacity thermal conductive frame. When a battery cell in the battery module has thermal runaway, the high specific heat capacity thermal conductive frame is used to bear and spatially average the heat emitted by the thermal runaway battery cell, while the insulation tube plays a role in reducing the rate at which the thermal runaway battery cell releases heat to the high specific heat capacity thermal conductive frame, providing time for the high specific heat capacity thermal conductive frame to average heat. Insulation plates are further placed on both sides of the battery cell safety valve to reduce the radiation heat transfer of the flame and high-temperature smoke generated by the thermal runaway battery cell to the adjacent battery cell. In addition, cooling measures are provided on the side of the high specific heat capacity thermal conductive frame to accelerate heat extraction.

[0007] The present invention is achieved by at least one of the following technical solutions.

[0008] A compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure comprises a plurality of battery cells and a high specific heat capacity heat conductive frame, wherein the high specific heat capacity heat conductive frame is provided with grooves corresponding to the plurality of battery cells, each battery cell is coated with a heat insulating tube, and the heat insulating tube and the battery cell are embedded in the groove; heat insulating plates are provided on both sides of each heat insulating tube, and the heat insulating plates are located on the top of the high specific heat capacity heat conductive frame.

[0009] Furthermore, the thermal insulation tube is made of an electrical insulating material with a thermal conductivity lower than 0.05 W / (m·K), and the wall thickness of the thermal insulation tube is 0.5 mm-2 mm.

[0010] Furthermore, the high specific heat capacity heat conducting frame is composed of a heat capacity greater than 2000 kJ / (m 3 The heat conduction frame is made of a metal material with a thermal conductivity greater than 200W / (m·K) and a thermal conductivity greater than 200W / (m·K), and the wall thickness of the high specific heat capacity heat conduction frame is 2mm-20mm.

[0011] Furthermore, a graphene electrical insulating sticker is provided on the surface of the high specific heat capacity thermal conductive frame exposed to the air.

[0012] Furthermore, each battery cell includes a battery cell body, a positive electrode, a negative electrode and a safety valve.

[0013] Furthermore, each heat insulation board is located on both sides of the safety valve, and the thickness of the heat insulation board is equal to the wall thickness of the high specific heat capacity heat conductive frame at the corresponding position.

[0014] Furthermore, the heat insulation board is made of an electrical insulating material with a thermal conductivity lower than 0.3 W / (m·K).

[0015] Furthermore, the height of the heat insulation board is 20mm-100mm.

[0016] Furthermore, the electrical insulating material is epoxy resin or polyimide.

[0017] Furthermore, a cooling measure is provided on the outer surface of the high specific heat capacity heat conductive frame, and the cooling measure is a phase change material or a liquid cooling plate.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention is conducive to simplifying the module structure, providing a thermal runaway propagation suppression structure with a smaller volume, and reducing the energy density loss of the battery module caused by safety measures, which is mainly reflected in the following aspects:

[0020] (1) No additional battery cell fixing device is required. The high specific heat capacity heat conductive frame in the present invention can also play the role of fixing the battery cell. In addition, the proposed high specific heat capacity heat conductive frame is connected to the battery pack box by bolt connection, and it can directly replace the support beam in the battery pack.

[0021] (2) Efficient use of heat dissipation elements. With existing sandwich structures, when a battery cell in a battery module experiences thermal runaway, only the heat dissipation elements of the adjacent battery cell can function. The thermal runaway barrier design for other battery cells in the module takes up a lot of space but does not function, resulting in waste. The thermal insulation tube proposed in the present invention, combined with a high specific heat capacity thermal conductive frame design, allows all battery cells to share one heat dissipation element, greatly improving the utilization rate of the heat dissipation element.

[0022] (3) Full utilization of the thermal mass of the battery cell. Due to the low thermal conductivity in the direction perpendicular to the core layer, local heating will cause the local temperature of the single cell to rise rapidly, and the single cell will enter a thermal runaway state when the overall average temperature of the single cell is low, and the thermal mass of the single cell cannot be fully utilized. In the battery module that uses the proposed structure, after a cell thermally runs away, the insulation tube wrapped around each cell allows the heat released by the thermal runaway cell to be preferentially conducted within the high specific heat capacity thermal conductive frame. After a certain period of time, the frame presents a relatively uniform temperature distribution, achieving uniform heating of all surfaces of each cell in the module, which not only makes full use of the thermal mass of the single cell itself, but also allows all cells in the module to participate in heat sharing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0024] Figure 1 A schematic diagram of a method for fixing a battery module in a battery box provided in an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of a compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure provided by an embodiment of the present invention;

[0026] Figure 3 A schematic diagram of the structure of a battery cell according to an embodiment of the present invention;

[0027] Figure 4 is a temperature curve of the surface of each battery cell after the third battery cell in the battery module of Example 2 of the present invention has thermal runaway;

[0028] Figure 5 The temperature curve of the surface of each battery cell after the third battery cell in the battery module of Example 3 of the present invention has thermal runaway;

[0029] In the figure, 1-battery module, 11-battery cell, 111-battery cell body, 112-positive electrode, 113-negative electrode, 114-safety valve, 12-thermal insulation tube, 13-high specific heat capacity thermal conductive frame, 14-thermal insulation board, 15-cooling measures, 16-connecting plate, 2-battery pack box, 3-bolts. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] A compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure comprises a battery module 1 and a high specific heat capacity heat conductive frame 13. The battery module comprises a plurality of battery cells 11, and the plurality of battery cells 11 are welded and fixed using an aluminum alloy connecting piece 16. The high specific heat capacity heat conductive frame 13 is provided with grooves corresponding to the plurality of battery cells 11, and each battery cell is coated with a heat insulating tube 12, and the heat insulating tube 12 and the battery cell are embedded in the groove; heat insulating plates 14 are provided on both sides of each heat insulating tube 12, and the heat insulating plates are located on the top of the high specific heat capacity heat conductive frame 13.

[0033] The wall thickness of the heat insulating tube 12 is 0.5 mm to 2 mm. The heat insulating tube 12 is made of an electrical insulating material with a thermal conductivity lower than 0.05 W / (m·K).

[0034] The high specific heat capacity heat conducting frame 13 has a specific heat capacity greater than 2000 kJ / (m 3 The high specific heat capacity heat conducting frame is made of a metal material with a thermal conductivity greater than 200 W / (m·K). The wall thickness of the high specific heat capacity heat conducting frame is 2 mm to 20 mm. The surface of the high specific heat capacity heat conducting frame exposed to air is provided with a graphene electrical insulation sticker.

[0035] like Figure 3 As shown, 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 board 14 is located on both sides of the safety valve 114, and the thickness of the heat insulation board is equal to the wall thickness of the high specific heat capacity heat conductive frame at the corresponding position, and the height of the heat insulation board is 20mm-100mm.

[0036] The heat insulation board is made of an electrical insulating material with high mechanical strength and a thermal conductivity lower than 0.3 W / (m·K), and may be epoxy resin or polyimide.

[0037] The outer surface of the high specific heat capacity heat conducting frame is provided with cooling means, which is a phase change material or a liquid cooling plate.

[0038] In this embodiment, the high specific heat capacity heat conductive frame is drilled with threaded holes on both end faces, and the battery module 1 is locked on the side wall of the battery pack box 2 by bolts 3 and threaded holes. Figure 1 shown.

[0039] Example 2

[0040] like Figure 2 As shown, the present invention proposes a compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure, including multiple battery cells 11, a thermal insulation tube 12 wrapped around each battery cell 11, a high specific heat capacity thermal conductive frame 13 embedded with all battery cells including the thermal insulation tube, and thermal insulation plates 14 located on both sides of each battery cell 11, and the thermal insulation plates 14 are placed on the top of the high specific heat capacity thermal conductive frame 13.

[0041] In this embodiment, the battery cell 11 has a geometric size of 130 mm*50 mm*180 mm, a chemical system of ternary lithium, a capacity of 50 Ah, and a density of 2055.1 kg / m 3 , the specific heat capacity is 830J / (kg·K), the thermal conductivity in the direction parallel to the core layer is 29.556W / (m·K), and the thermal conductivity in the direction perpendicular to the core layer is 0.892W / (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 .

[0042] The material of the heat insulation tube 12 is silicon dioxide nano-aerogel, whose thermal conductivity is 0.018W / (m·K) at room temperature, thickness is 0.75mm, density is 0.21kg / m 3 , the specific heat capacity is 590.95 J / (kg·K).

[0043] The material of the high specific heat capacity thermal conductive frame 13 is aluminum, with a thermal conductivity of 202.4W / (m·K), a density of 0.21kg / m3, and a specific heat capacity of 590.95J / (kg·K). The wall thickness of the high specific heat capacity thermal conductive frame between the battery cells is 6mm, and the wall thickness of the two ends of the high specific heat capacity thermal conductive frame 13 is 7.5mm.

[0044] The material of the heat insulation board 14 is epoxy resin, with a thermal conductivity of 0.15W / (m·K), a thickness equal to the wall thickness of the high specific heat capacity heat conductive frame 3 at the corresponding position, a height of 40mm, a density of 1130kg / m3, and a specific heat capacity of 1221J / (kg·K). The heat insulation board 14 is placed on both sides of the battery safety valve 114 and fixed with epoxy AB super glue. The surface of the high specific heat capacity heat conductive frame 13 exposed to the air is affixed with graphene insulation paper to avoid unnecessary short circuits.

[0045] The battery module of this embodiment includes six battery cells 11, and the six battery cells 11 are welded and fixed in series using aluminum alloy connecting pieces 16. The grade of the aluminum alloy is 6061, and the thickness of the connecting piece 16 is 3 mm.

[0046] like Figure 4 As shown, for the battery module using the thermal runaway propagation suppression structure proposed by the present invention, after the third battery cell (from left to right) was punctured and caused thermal runaway, the left and right sides of the affected battery cells in the module showed almost consistent temperature changes, indicating that the affected battery cells were heated uniformly. Among them, the peak temperature of the second battery cell was 118°C, and the peak temperature of the first battery cell was 95°C. The results show that thermal runaway did not propagate in the battery module.

[0047] Example 3

[0048] like Figure 2As shown, the present invention proposes a compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure, including multiple battery cells 11, a thermal insulation tube 12 wrapped around each battery cell 11, a high specific heat capacity thermal conductive frame 13 embedded with all battery cells including the thermal insulation tube, and thermal insulation plates 14 located on both sides of each battery cell 11, the thermal insulation plates 14 are placed on the top of the high specific heat capacity thermal conductive frame 13, and cooling measures 15 are provided on the sides of the high specific heat capacity thermal conductive frame 13.

[0049] In this embodiment, the battery cell 11 has a geometric size of 130 mm*50 mm*180 mm, a chemical system of ternary lithium, a capacity of 50 Ah, and a density of 2055.1 kg / m 3 , the specific heat capacity is 830J / (kg·K), the thermal conductivity in the direction parallel to the core layer is 29.556W / (m·K), and the thermal conductivity in the direction perpendicular to the core layer is 0.892W / (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 .

[0050] The material of the heat insulation tube 12 is silicon dioxide nano-aerogel, whose thermal conductivity is 0.018W / (m·K) at room temperature, thickness is 0.75mm, density is 0.21kg / m 3 , the specific heat capacity is 590.95 J / (kg·K).

[0051] The material of the high specific heat capacity thermal conductive frame 13 is aluminum, with a thermal conductivity of 202.4W / (m·K), a density of 0.21kg / m3, and a specific heat capacity of 590.95J / (kg·K). The wall thickness of the high specific heat capacity thermal conductive frame between the battery cells is 6mm, and the wall thickness of the two ends of the high specific heat capacity thermal conductive frame 13 is 7.5mm.

[0052] The material of the heat insulation board 14 is epoxy resin, with a thermal conductivity of 0.15W / (m·K), a thickness equal to the wall thickness of the high specific heat capacity heat conductive frame 13 at the corresponding position, a height of 40mm, a density of 1130kg / m3, and a specific heat capacity of 1221J / (kg·K). The heat insulation board 14 is placed on both sides of the battery safety valve 114 and fixed with epoxy AB super glue. The surface of the high specific heat capacity heat conductive frame 13 exposed to the air is affixed with graphene insulation paper to avoid unnecessary short circuits.

[0053] Cooling measure 5 is phase change material cooling. The phase change material used is solid-solid phase change material with a thickness of 8 mm, a phase change temperature of 42 °C, a phase change latent heat of 180,000 J / kg, a specific heat capacity of 1800 J / (kg·K), and a density of 800 kg / m 3 .

[0054] The battery module of this embodiment includes six battery cells 11, and the six battery cells 11 are welded and fixed in series using aluminum alloy connecting pieces 16. The grade of the aluminum alloy is 6061, and the thickness of the connecting piece 16 is 3 mm.

[0055] like Figure 5 As shown, for the battery module using the thermal runaway propagation suppression structure proposed by the present invention, after the third battery cell (from left to right) was punctured and caused thermal runaway, the left and right sides of the affected battery cells in the module showed almost consistent temperature changes, indicating that the affected battery cells were heated evenly. Among them, the peak temperature of the second battery cell was 105°C, and the peak temperature of the first battery cell was 85°C. The results show that thermal runaway did not propagate in the battery module.

[0056] The embodiment of the present invention provides a compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure. When a battery cell in the battery module experiences thermal runaway, the high specific heat capacity heat conductive frame 13 is used to bear and spatially average the heat emitted by the thermal runaway battery cell, while the heat insulating tube 12 plays a role in reducing the rate at which the thermal runaway battery cell releases heat to the high specific heat capacity heat conductive frame 13, providing time for the high specific heat capacity heat conductive frame 13 to average heat. Insulation plates 14 are further placed on both sides of the safety valve of the battery cell 11 to reduce the radiation heat transfer of the flame and high-temperature smoke generated by the thermal runaway battery cell to the adjacent battery cell. In addition, cooling measures 15 are provided on the side of the high specific heat capacity heat conductive frame to accelerate heat extraction.

[0057] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure, characterized in that: The invention comprises a plurality of battery cells (11) and a high specific heat capacity heat conductive frame (13), wherein the high specific heat capacity heat conductive frame (13) is provided with grooves corresponding to the plurality of battery cells (11), each battery cell (11) is coated with a heat insulating tube (12), and the heat insulating tube (12) and the battery cell (11) are embedded in the groove; and heat insulating plates (14) are provided on both sides of each heat insulating tube (12), and the heat insulating plates (14) are located on the top of the high specific heat capacity heat conductive frame (13).

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

3. A compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure according to claim 1, characterized in that: The high specific heat capacity heat conducting frame (13) is composed of a material with a specific heat capacity greater than 2000 kJ / (m 3 The high specific heat capacity heat conducting 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 to 20 mm.

4. A compact and lightweight lithium-ion battery module thermal runaway propagation suppression structure according to claim 1, characterized in that: A graphene electrical insulation sticker is provided on the surface of the high specific heat capacity heat conducting frame (13) exposed to the air.

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

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

7. A compact and 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 electrical insulating material with a thermal conductivity lower than 0.3 W / (m·K).

8. A compact and 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 and 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 and 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 heat conducting frame (13) is provided with a cooling measure, and the cooling measure is a phase change material or a liquid cooling plate.

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