Staged thermal isolation device and battery module

Abstract

The invention relates to the technical field of energy storage battery protection, and discloses a staged thermal isolation device and a battery module, the staged thermal isolation device comprises a heat conduction layer, a heat absorption protection layer and an isolation layer, one side of the heat conduction layer is suitable for being connected with a battery cell; the heat absorption protection layer comprises a heat absorption plate and fire extinguishing assemblies, one side of the heat absorption plate is connected with the side, away from the battery cell, of the heat conduction layer, the heat absorption plate is filled with a phase change material, and the multiple fire extinguishing assemblies are connected with the heat absorption plate; the isolating layer comprises a fixing body and an isolating baffle, a cavity with an opening in one end is formed in the fixing body, the opening end of the fixing body is connected with the side, away from the heat conduction layer, of the heat absorption plate, and the isolating baffle is arranged in the cavity. And the response speed and the overall safety of the battery module under the thermal runaway condition are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage battery protection, in particular to a staged thermal isolation device and a battery module. BACKGROUND

[0002] Lithium ion battery is a rechargeable chemical power supply with lithium as the main active material, which has the advantages of high energy density, long cycle life, low self-discharge rate and no memory effect. Multiple lithium ion batteries are combined to form a battery module, which is widely used in portable electronic devices, electric vehicles and energy storage systems. In recent years, with the development of new energy industry, especially in the promotion of large-scale energy storage systems, the installed capacity of lithium ion batteries is also increasing. With the wide application of lithium ion batteries in energy storage power stations, electric vehicles and other fields, their safety has attracted increasing attention. Especially in the use of high energy density batteries, thermal runaway has become one of the key bottlenecks limiting their application. Thermal runaway of lithium ion batteries is usually triggered by overcharging, short circuit, mechanical damage and other factors, which in turn triggers a series of intense exothermic reactions, such as electrolyte combustion and positive material oxygen release, which may eventually lead to thermal spread and even battery module explosion, causing serious personal and property damage.

[0003] A battery module thermal isolation device includes a heat insulation layer, a fire retardant layer and a buffer layer. The heat insulation layer is connected to the battery cell through the buffer layer, which is used to absorb the size change caused by the expansion of the battery cell. The fire retardant layer is connected to the heat insulation layer. The heat insulation layer can effectively limit the spread of high temperature to the surrounding battery cells by reducing the heat conduction efficiency when the battery cell experiences thermal runaway. The fire retardant layer can inhibit the spread of fire when the battery cell is on fire. This thermal isolation device can only passively delay the spread of heat, but the response is slow and it is difficult to suppress the thermal runaway phenomenon in time and quickly. SUMMARY

[0004] Therefore, the present application provides a staged thermal isolation device to solve the problem of slow response and poor thermal blocking effect of existing battery module fire extinguishing.

[0005] In a first aspect, the present application provides a staged thermal isolation device, comprising:

[0006] A heat-conducting layer, one side of the heat-conducting layer being adapted to be connected to a battery cell;

[0007] A heat-absorbing protective layer, the heat-absorbing protective layer comprising: a heat-absorbing plate and a fire extinguishing assembly, one side of the heat-absorbing plate being connected to the side of the heat-conducting layer away from the battery cell, the heat-absorbing plate being filled with a phase change material, the heat-absorbing plate being adapted to absorb heat transferred from the battery cell through the heat-conducting layer when the battery cell experiences thermal runaway, a plurality of fire extinguishing assemblies being connected to the heat-absorbing plate, the fire extinguishing assemblies being adapted to release fire extinguishing medium after the heat-absorbing plate reaches a threshold temperature;

[0008] The isolation layer comprises a fixed body and an isolation baffle, the fixed body is internally provided with a cavity with an open end, and the open end of the fixed body is connected to the side of the heat absorption plate away from the heat conduction layer, and the isolation baffle is arranged in the cavity, and the isolation baffle has a folded state folded in the cavity at normal temperature and an unfolded state unfolded and covering the surface of the battery cell at high temperature.

[0009] Advantages

[0010] The heat conduction layer can quickly conduct the heat generated by the battery cell to the heat absorption protection layer, the heat absorption plate in the heat absorption protection layer absorbs and buffers the conducted heat by using the phase change material, and the heat is significantly delayed from spreading outward; the fire extinguishing assembly releases the fire extinguishing medium after the heat absorption plate reaches the set temperature threshold, has an active fire extinguishing function, and effectively inhibits the flame spread after the battery cell catches fire; the isolation baffle in the isolation layer is unfolded to cover the surface of the battery cell under high-temperature excitation, further forming a physical barrier to inhibit the spread of thermal runaway to adjacent battery cells. The heat isolation device realizes a cooperative protection mechanism of rapid response, effective absorption, active fire extinguishing and physical isolation, and improves the safety of the battery module in the case of thermal runaway.

[0011] In an optional embodiment, the fire extinguishing assembly comprises a fixed device and a gas fire extinguishing device, the fixed device is connected to the side wall of the heat absorption plate, and the gas fire extinguishing device is arranged on the fixed device.

[0012] In an optional embodiment, the gas fire extinguishing device comprises a gas storage unit, a sleeve and a gas guide pipe, the fixed device is provided with a fixed hole, the gas storage unit is arranged in the fixed hole, the gas storage unit is internally provided with a gas storage cavity, the gas storage cavity is filled with fire-retardant gas, the gas storage unit is provided with a gas outlet groove, the sleeve is sleeved on the gas storage unit and seals the gas outlet groove, and one end of the gas guide pipe is inserted into the sleeve and connected with the gas outlet groove.

[0013] Advantages

[0014] The gas storage unit is internally provided with a gas storage cavity and filled with fire-retardant gas, the gas outlet groove is used for releasing the fire extinguishing medium, the sleeve seals the gas outlet groove, effectively seals before triggering, and ensures stable gas storage. One end of the gas guide pipe is connected with the gas storage unit, and the other end is embedded in the frame groove of the battery module, which can guide the fire extinguishing medium to the key area between the battery cells, forming a rapid and efficient fire extinguishing path.

[0015] In an optional embodiment, the gas outlet groove is provided with a heat-sensitive embrittlement layer.

[0016] In an alternative embodiment, a slide rail is formed on the inner wall of the cavity, and a hot melt fixing block is arranged on the slide rail, and the isolation baffle is connected with the hot melt fixing block.

[0017] In an alternative embodiment, the isolation baffle is a shape memory alloy baffle.

[0018] In an alternative embodiment, the heat conduction layer is provided with a plurality of wave-shaped heat conduction structures.

[0019] Advantages

[0020] The wave-shaped heat conduction structure increases the surface area of the heat conduction layer, helps to improve the heat diffusion efficiency, and promotes the heat to be transmitted to the heat absorption protective layer more uniformly, avoiding the accumulation of local hot spots. On the other hand, the wave-shaped heat conduction structure has certain elastic buffering performance, can adapt to the size change of the battery cell in the process of thermal expansion and cold contraction, and enhances the fitting stability between the heat conduction layer and the battery cell.

[0021] In an alternative embodiment, a plurality of pressure release micro-holes are arranged at intervals on the trough section of the wave-shaped heat conduction structure.

[0022] Advantages

[0023] When the battery cell burns, the gas pressure inside the battery cell will increase, and the gas can slowly seep out through the pressure release micro-holes, avoiding the explosion of the battery cell caused by sudden increase of pressure.

[0024] In an alternative embodiment, a plurality of heat absorption cavities are formed on the heat absorption plate, and the heat absorption cavities are filled with the phase change material.

[0025] In a second aspect, the present application also provides a battery module, comprising: a battery shell and a plurality of battery cells, the battery shell is provided with a plurality of battery cells at intervals along the length direction, and each battery cell is connected with a staged heat isolation device near one side of the first end face or the second end face of the battery shell.

[0026] Advantages

[0027] Each battery cell is provided with a staged heat isolation device near the end of the battery shell, realizing the directional integrated arrangement of the battery cell unit and the heat isolation device. When a certain battery cell occurs thermal runaway, the corresponding heat isolation device can respond in the first time, and implement multiple protection measures such as heat conduction, absorption, fire extinguishing and physical isolation, effectively inhibit the spread of heat to adjacent battery cells, and prevent the occurrence of chain reaction. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor based on these drawings.

[0029] Figure 1 Structure diagram of the phase separation heat insulation device of the embodiment of the present application;

[0030] Figure 2 Structure diagram of the heat conduction layer of the embodiment of the present application;

[0031] Figure 3 Side view of the wave-shaped heat conduction structure of the embodiment of the present application;

[0032] Figure 4 Structure diagram of the heat absorption protective layer of the embodiment of the present application;

[0033] Figure 5 Structure diagram of the gas fire extinguishing device of the embodiment of the present application;

[0034] Figure 6 Structure diagram of the insulation layer of the embodiment of the present application;

[0035] Figure 7 Schematic diagram of the battery module of the embodiment of the present application.

[0036] Explanation of reference signs:

[0037] 1, heat conduction layer, 11, wave-shaped heat conduction structure, 12, pressure release micro-hole, 13, riveting hole;

[0038] 2, electric core;

[0039] 3, heat absorption protective layer, 31, heat absorption plate, 311, heat absorption cavity, 32, fire extinguishing assembly, 321, fixing device, 322, gas fire extinguishing device, 3221, gas storage unit, 3222, sleeve, 3223, gas guide pipe, 3224, gas storage cavity, 3225, gas outlet groove, 3226, heat-sensitive embrittlement layer;

[0040] 4, insulation layer, 41, fixed body, 42, insulation baffle, 43, slide rail, 44, hot melt fixed clamping block. Specific embodiments

[0041] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0042] The embodiments of the present application are described below with reference to the drawings. Figures 1 to 7

[0043] According to the embodiments of the present application, in one aspect, a staged thermal isolation device is provided, comprising: a heat conduction layer 1, a heat absorption protection layer 3 and an isolation layer 4, one side of the heat conduction layer 1 is adapted to be connected with a battery cell 2; the heat absorption protection layer 3 comprises: a heat absorption plate 31 and a fire extinguishing assembly 32, one side of the heat absorption plate 31 is connected with the side of the heat conduction layer 1 away from the battery cell 2, the heat absorption plate 31 is filled with a phase change material, the heat absorption plate 31 is adapted to absorb heat transferred through the heat conduction layer 1 when the battery cell 2 is in thermal runaway, a plurality of fire extinguishing assemblies 32 are connected with the heat absorption plate 31, the fire extinguishing assembly 32 is adapted to release fire extinguishing medium after the heat absorption plate 31 reaches a threshold temperature; the isolation layer 4 comprises: a fixed body 41 and an isolation baffle 42, the fixed body 41 is internally provided with a cavity with an open end, and the open end of the fixed body 41 is connected with the side of the heat absorption plate 31 away from the heat conduction layer 1, the isolation baffle 42 is arranged in the cavity, and the isolation baffle 42 has a folded state of being folded in the cavity at normal temperature, and an unfolded state of being unfolded and covering the surface of the battery cell 2 at high temperature.

[0044] The heat conduction layer 1 is provided with a riveting hole 13 at each corner, when the heat conduction layer 1 is connected with the battery cell 2, it will be directly attached to the surface of the battery cell 2 shell through the heat conduction silica gel first, and then riveted with the battery cell 2 through the riveting hole 13, to realize the fixed connection with the battery cell 2. The heat conduction layer 1 is attached to the outer surface of the battery cell 2, which can quickly conduct the heat generated by the battery cell 2 during operation to the external structure. The heat conduction layer 1 is made of high thermal conductivity materials such as copper foil, aluminum foil or graphite sheet, to enhance the timeliness and uniformity of heat transfer.

[0045] The heat absorption protection layer 3 is arranged on the side of the heat conduction layer 1 away from the battery cell 2, the heat absorption plate 31 adopts a metal shell structure, and is filled with phase change materials such as paraffin, low melting point metal alloy or fatty acid compound in the inside, the phase change material can absorb a large amount of heat at the initial stage of thermal runaway of the battery cell 2, to realize temperature buffering and delay the spread of heat. A plurality of fire extinguishing assemblies 32 are uniformly arranged on the heat absorption plate 31, after the heat absorption plate 31 is conducted to the threshold temperature, the fire extinguishing assembly 32 is automatically opened and releases the preset fire extinguishing medium, such as inert gas or dry powder extinguishing agent, which can quickly suppress the initial flame caused by thermal runaway and avoid the spread of fire.

[0046] ​The isolation layer 4 is located at the end of the heat absorption protective layer 3 away from the heat conduction layer 1, and can physically shield the battery cell 2 when the battery cell 2 is completely out of control. The isolation layer 4 includes a fixed body 41 and an isolation baffle 42 arranged therein, and the fixed body 41 is fixed to the heat absorption protective layer 3 and the side wall of the battery module by epoxy resin. When the battery cell 2 is not on fire, the isolation baffle 42 is accommodated in the cavity in a folded state; when the battery cell 2 is on fire and the temperature of the battery module rises, the isolation baffle 42 is expanded by heat and covers the external surface of the battery cell 2, forming a physical barrier to effectively block the heat and flame from spreading to the adjacent battery cell 2.

[0047] The heat conduction layer 1 can conduct the heat on the battery cell 2 to the heat absorption protective layer 3, and in the initial stage of the heat loss of the battery cell 2, the heat conduction layer 1 can effectively inhibit the spread of heat and release the fire extinguishing medium to effectively inhibit the combustion of the battery cell 2; when the battery cell 2 is on fire and the heat is out of control, the isolation layer 4 isolates the battery cell 2, effectively preventing the spread of heat in the battery module and blocking the flame and heat radiation. The heat isolation device realizes delayed temperature rise, inhibited combustion to physical isolation of the battery cell 2 through multi-stage response to the heat loss of the battery cell 2, greatly improving the thermal safety performance of the battery module. Through the rapid heat conduction of the heat conduction layer 1, the heat buffering and fire extinguishing response of the heat absorption protective layer 3, and the automatic expansion and blocking function of the isolation layer 4, a multi-stage collaborative protection mechanism of “heat conduction-heat absorption-fire extinguishing-blocking” is constructed, effectively improving the response speed and overall safety of the battery module in the case of heat loss.

[0048] In one embodiment, a plurality of wave-shaped heat conduction structures 11 are arranged on the heat conduction layer 1.

[0049] Specifically, the plurality of wave-shaped heat conduction structures 11 are arranged along the height direction of the battery cell 2, and the wave-shaped heat conduction structure 11 is a sheet-shaped metal with continuous undulations in a wave shape, which is pressed from a high-thermal-conductivity material and has a uniform wave crest and wave trough after anodic oxidation treatment to enhance corrosion resistance. The heat conduction structure significantly increases the contact area between the heat conduction layer 1 and the battery cell 2, and improves the heat transfer efficiency per unit time. At the same time, the battery cell 2 will deform elastically when subjected to external pressure, and the heat conduction structure can alleviate the damage to the battery cell 2 caused by external impact. At the same time, the wave-shaped heat conduction structure 11 provides a certain elastic buffering performance for the battery cell 2, which can adapt to the size change caused by the heat imbalance and expansion of the battery cell 2, and maintain the stability of the fit between the heat conduction layer 1 and the battery cell 2.

[0050] In one embodiment, a plurality of pressure release micro-holes 12 are arranged on the wave trough section of the wave-shaped heat conduction structure 11.

[0051] Specifically, the wave trough section of the wavy heat conduction structure 11 is provided with a plurality of pressure release micro-holes 12 spaced apart along the width direction of the battery cell 2. When the battery cell 2 abnormally heats up, gas is generated. When the pressure in the battery cell 2 rises due to the generation of gas, the pressure release micro-holes 12 can provide a gas discharge channel for the battery cell 2, preventing the rapid accumulation of pressure in the battery cell 2, which can cause the battery cell 2 to rupture or explode.

[0052] The pore size of the pressure release micro-holes 12 can be designed to be 0.1mm to 1mm, and the hole distance is determined according to the size of the heat conduction layer 1 and the size of the battery cell 2, to ensure that the gas can be effectively released without significantly weakening the mechanical strength of the heat conduction layer 1.

[0053] In one embodiment, the heat absorption plate 31 is provided with a plurality of heat absorption cavities 311.

[0054] Specifically, the heat absorption plate 31 is made of aluminum plastic composite film, which has good heat conduction performance, and is bonded to the outer side of the heat conduction layer 1 by high-temperature resistant double-sided adhesive tape. The heat conduction plate is processed with a plurality of heat absorption cavities 311 arranged in an array, the cavities are honeycomb-shaped, and penetrate the thickness direction of the heat absorption plate 31.

[0055] Each heat absorption cavity 311 is filled with phase change material (a mixture of paraffin and expanded graphite, with red phosphorus flame retardant added), and the cavity is sealed by aluminum plastic composite film after being filled with phase change material and vacuum heat sealed to prevent leakage of the phase change material. The phase change material can play a role in heat absorption and buffering, and its normal state is solid. When the temperature reaches a threshold value, the paraffin melts and absorbs latent heat, slowing down the temperature rise rate. In addition, it also has the effect of flame retardation and explosion suppression. The expanded graphite forms a heat conduction network, and the red phosphorus releases free radicals when heated, interrupting the combustion chain reaction. The aluminum plastic composite film prevents the phase change material from leaking out after melting, prevents the liquid paraffin from flowing everywhere, maintains the stability of the structure, and improves the heat absorption efficiency.

[0056] In one embodiment, the fire extinguishing assembly 32 includes a fixing device 321 and a gas fire extinguishing device 322, the fixing device 321 is connected to the side wall of the heat absorption plate 31, and the gas fire extinguishing device 322 is arranged on the fixing device 321.

[0057] The fixing device 321 is connected to the side wall of the heat absorption plate 31, which is used to stably support the gas fire extinguishing device 322 and ensure that it can accurately release the fire extinguishing medium when triggered by heat. Specifically, the fixing device 321 is fixed on the side wall of the heat absorption plate 31, and the gas fire extinguishing device 322 is arranged on the fixing device 321 to ensure that the fire extinguishing medium can be completely released. The gas fire extinguishing device 322 is in a sealed state, and when the temperature of the heat absorption plate 31 rises to a certain temperature, the gas fire extinguishing device 322 is opened, accurately intervening in the early stage of thermal runaway of the battery cell 2, effectively reducing the risk of heat diffusion and combustion.

[0058] In one embodiment, the gas fire extinguishing device 322 comprises a gas storage unit 3221, a sleeve 3222 and a gas guide pipe 3223, the fixing device 321 is provided with a fixing hole, the gas storage unit 3221 is arranged in the fixing hole, the gas storage unit 3221 is provided with a gas storage cavity 3224, the gas storage cavity 3224 is filled with fire-retardant gas, the gas storage unit 3221 is provided with a gas outlet groove 3225, the sleeve 3222 is sleeved on the gas storage unit 3221 and blocks the gas outlet groove 3225, and one end of the gas guide pipe 3223 is inserted into the sleeve 3222 and connected with the gas outlet groove 3225.

[0059] Specifically, the gas storage unit 3221 is a hollow cylindrical structure made of polyimide film, which is installed in the fixing hole of the fixing device 321 or is directly fixed on the side wall of the heat absorption protection layer 3 by laser welding. The gas storage unit 3221 is internally provided with the gas storage cavity 3224 filled with fire-retardant gas such as nitrogen, carbon dioxide or perfluorohexanone powder, which is kept in a sealed state under normal conditions to ensure stable pressure. The gas storage unit 3221 is provided with the gas outlet groove 3225 on the outer wall, and the outlet of the gas outlet groove 3225 is sleeved and blocked by the sleeve 3222. One end of the gas guide pipe 3223 is inserted into the sleeve 3222 and communicates with the gas outlet groove 3225, and the other end is embedded in the frame groove of the battery module and is arranged adjacent to the arrangement area of the plurality of battery cells 2. The gas guide pipe 3223 can be made of high-temperature resistant hose or metal bellows to ensure stable and reliable gas guide path.

[0060] In one embodiment, the gas outlet groove 3225 is provided with a heat-sensitive embrittlement layer 3226.

[0061] Specifically, the gas storage unit 3221 is thinned at the cavity wall at the gas outlet groove 3225 to form a heat-sensitive embrittlement area, and the heat-sensitive embrittlement area is coated with a heat-sensitive embrittlement coating. The heat-sensitive embrittlement layer 3226 covers the inside of the gas outlet groove 3225 of the gas storage unit 3221 and can be made of hot melt film or high molecular embrittlement material, which remains stable at room temperature or normal working temperature and plays a role in closing the gas outlet groove 3225 and sealing the gas storage cavity 3224.

[0062] The heat absorption protection layer 3 will heat up due to thermal runaway of the battery cell 2, the heat-sensitive embrittlement area of the gas storage unit 3221 breaks when the heat absorption plate 31 reaches the critical temperature, the gas outlet groove 3225 is opened, and the fire-retardant gas is quickly delivered to the gap between the battery cells 2 through the gas guide pipe 3223 and directly acts on the fire source part to reduce the oxygen concentration and effectively inhibit the spread of fire.

[0063] In one embodiment, the inner wall of the cavity is provided with a sliding rail 43, the sliding rail 43 is provided with a hot melt fixing block 44, and the isolation baffle 42 is connected with the hot melt fixing block 44.

[0064] Specifically, the cavity is a semi-closed rectangular space arranged inside the fixed body 41, one end of which is open, and the inner wall of which is symmetrically provided with sliding rails 43 along the length direction, which provide sliding paths for the unfolding of the isolation baffle 42. The surface of the sliding rail 43 is coated with a silicon carbide coating to reduce frictional resistance and ensure the smoothness of the unfolding process of the isolation baffle 42.

[0065] The hot-melt fixing block 44 is installed in the sliding rail 43 and is fixedly connected with the sliding rail 43 in the cavity, thereby stably fixing the isolation baffle 42 in the folded state. The hot-melt fixing block 44 is made of a nickel-based high-temperature alloy material, which has good mechanical strength at room temperature. When the temperature rises to the melting point of the hot-melt fixing block 44, the fixing block melts, the isolation baffle 42 slides out along the sliding rail 43 and unfolds, and covers the surface of the battery cell 2.

[0066] In one embodiment, the isolation baffle 42 is a shape memory alloy baffle.

[0067] Specifically, the shape memory alloy baffle is preferably made of a nickel-titanium alloy (NiTi) or a copper-based memory alloy material, which can be processed into a folded state at room temperature and maintain the stable shape, and quickly recover to the preset unfolded shape after reaching a specific excitation temperature (for example, 70℃-120℃), thereby having good temperature control responsiveness and repeated reliability.

[0068] In this embodiment, the isolation baffle 42 is folded into a Z-shaped compressed state inside the cavity and is fixed in the folded state by the hot-melt fixing block 44. When the battery cell 2 undergoes thermal runaway and the temperature in the cavity rapidly rises to the phase transition temperature range of the shape memory alloy, the isolation baffle 42 unfolds and covers the surface of the battery cell 2, thereby forming effective physical isolation and blocking the spread of heat radiation, flames and high-temperature gas between adjacent battery cells 2.

[0069] According to the embodiment of the present application, on the other hand, a battery module is also provided, which comprises the staged thermal isolation device and further comprises: a battery housing and a plurality of battery cells 2, the battery housing is provided with a plurality of battery cells 2 spaced along the length direction thereof, and each battery cell 2 is connected with one staged thermal isolation device near one side of the first end face or the second end face of the battery housing.

[0070] Specifically, the battery module comprises a battery housing and a plurality of battery cells 2, and the battery cells 2 are linearly arranged or matrixly arranged in the battery housing. Each battery cell 2 is provided with a set of staged thermal isolation devices, the thermal isolation devices are arranged in close contact with the surface of the battery cell 2, and are alternately arranged along the length direction of the battery housing in the order of “battery cell 2-isolation device-battery cell 2-isolation device”, thereby forming a modular and periodic layout.

[0071] Once the cell 2 shows signs of thermal runaway during operation, its corresponding staged thermal isolation device first responds, quickly conducting heat to the heat absorption protection layer 3 through the heat conduction layer 1, and the phase change material in the heat absorption plate 31 absorbs heat and delays transmission. At the same time, the isolation baffle 42 in the isolation layer 4 of the adjacent cell 2 away from the side of its staged thermal isolation device pops out, first protecting the adjacent cell 2 from being damaged. If the temperature continues to rise, the fire extinguishing assembly 32 starts to release fire-retardant gas to directly suppress the fire source; at the same time, the isolation baffle 42 in the isolation layer 4 expands under the action of high temperature, covering the heat source cell 2, and forming a physical blocking barrier to prevent the flame or heat from spreading to both sides.

[0072] Although the embodiments of the present application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the present application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A staged thermal isolation device, characterized by, The application relates to a thermal runaway protection device for a battery cell, which comprises the following parts: a heat-conducting layer (1) which is suitable for being connected with a battery cell (2) on one side; a heat-absorbing protection layer (3) which comprises a heat-absorbing plate (31) and a fire extinguishing assembly (32), one side of the heat-absorbing plate (31) is connected with the side of the heat-conducting layer (1) which is away from the battery cell (2), the heat-absorbing plate (31) is filled with a phase change material, the heat-absorbing plate (31) is suitable for absorbing heat transferred from the battery cell (2) through the heat-conducting layer (1) when the battery cell (2) is in thermal runaway, and a plurality of fire extinguishing assemblies (32) are connected with the heat-absorbing plate (31), the fire extinguishing assemblies (32) are suitable for releasing fire extinguishing medium after the heat-absorbing plate (31) reaches a threshold temperature; an isolation layer (4) which comprises a fixed body (41) and an isolation baffle (42), the fixed body (41) is internally provided with a cavity which is open at one end, and the open end of the fixed body (41) is connected with the side of the heat-absorbing plate (31) which is away from the heat-conducting layer (1), the isolation baffle (42) is arranged in the cavity, and the isolation baffle (42) has a folded state of being folded in the cavity at normal temperature and an unfolded state of being unfolded and covering the surface of the battery cell (2) at high temperature.

2. The staged thermal isolation device of claim 1, wherein, The fire extinguishing assembly (32) comprises a fixing device (321) and a gas fire extinguishing device (322), the fixing device (321) is connected with the side wall of the heat-absorbing plate (31), and the gas fire extinguishing device (322) is arranged on the fixing device (321).

3. The staged thermal isolation device of claim 2, wherein, The gas fire extinguishing device (322) comprises a gas storage unit (3221), a sleeve (3222) and a gas guide pipe (3223), the fixing device (321) is provided with a fixing hole, the gas storage unit (3221) is arranged in the fixing hole, the gas storage unit (3221) is internally provided with a gas storage cavity (3224) which is filled with fire-retardant gas, the gas storage unit (3221) is provided with a gas outlet groove (3225), the sleeve (3222) is sleeved on the gas storage unit (3221) and seals the gas outlet groove (3225), and one end of the gas guide pipe (3223) is inserted into the sleeve (3222) and connected with the gas outlet groove (3225).

4. The staged thermal isolation device of claim 3, wherein, The gas outlet groove (3225) is provided with a heat-sensitive fragile layer (3226).

5. The staged thermal isolation device of claim 1, wherein, The inner wall of the cavity is provided with a sliding rail (43), the sliding rail (43) is provided with a hot melt fixing clamping block (44), and the isolation baffle (42) is connected with the hot melt fixing clamping block (44).

6. The staged thermal isolation device of claim 5, wherein, The isolation baffle (42) is a shape memory alloy baffle.

7. The staged thermal isolation device of claim 1, wherein, The heat-conducting layer (1) is provided with a plurality of wave-shaped heat-conducting structures (11).

8. The staged thermal isolation device of claim 7, wherein, A plurality of pressure release micro-holes (12) are arranged on the trough section of the wave-shaped heat-conducting structure (11) at intervals.

9. The staged thermal isolation device of claim 1, wherein, A plurality of heat-absorbing cavities (311) are arranged on the heat-absorbing plate (31), and the heat-absorbing cavities (311) are filled with the phase change material.

10. A battery module comprising the staged thermal isolation device of any one of claims 1-9, wherein, The application relates to a thermal runaway protection device for a battery cell, which comprises the following parts: A battery casing and multiple battery cells (2), wherein multiple battery cells (2) are arranged in the battery casing at intervals along its length, and each battery cell (2) is connected to a staged thermal isolation device on one side near the first end face or the second end face of the battery casing.

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