Composite protection structure, power battery box cover and power battery

Abstract

The utility model discloses a kind of composite protective structures, between cover and electric core, for the protection of power battery box cover cover, including impact resistance layer and gradient heat insulation layer stacked above impact resistance layer;The impact resistance layer is made of high-temperature-resistant metal material or ablation material;The gradient heat insulation layer includes aerogel-ceramic fiber composite pad and intumescent flame-retardant coating, the aerogel-ceramic fiber composite pad has nano-porous structure, the intumescent flame-retardant coating can carbonize expansion.This technical scheme realizes double protection mechanism by the coupling effect of multiple physical fields: in the stage of jet impact, impact resistance layer relieves or resists high-temperature eruption material high-speed impact using its material properties;In the stage of heat conduction, gradient heat insulation layer inhibits gas convection heat transfer through the nano-porous structure of aerogel-ceramic fiber composite pad, and builds heat insulation barrier by the carbonization reaction of intumescent flame-retardant coating.

Description

Technical Field

[0001] This utility model relates to the field of power battery safety protection technology, and more specifically to a composite protection structure, a power battery box cover, and a power battery. Background Technology

[0002] As lithium-ion battery energy density evolves towards high-energy systems above 400 Wh / kg, high-nickel ternary, semi-solid-state electrolyte, and all-solid-state electrolyte systems have become research hotspots in the field of electrochemical energy storage. However, thermodynamic analysis shows that the increase in system energy density will directly lead to an increase in the enthalpy of reaction per unit mass during cell thermal runaway by about 18-25%.

[0003] When these high-energy battery cells trigger thermal runaway, the ejected material at the safety valve exhibits multiphase flow characteristics, with the gas-solid mixture ejected at velocities of 120-180 m / s and temperatures exceeding 1000°C. It is noteworthy that these high-temperature particles, under the influence of turbulent flow, create a continuous thermo-mechanical coupling impact on the battery module's top cover. When the local temperature of the aluminum alloy substrate in the cover exceeds its solidus temperature, liquid phase migration occurs, ultimately leading to structural failure or thermal decomposition and combustion of the electrophoretic coating.

[0004] Existing protective technologies are mainly based on silicate mineral insulation treatment. Typical implementation schemes include composite barrier layers of mica paper or mica board. However, when the temperature exceeds 700℃, the mechanical properties of mica deteriorate sharply, causing high-speed ejected materials to break through the mica. These defects make it difficult for existing insulation solutions to meet the technical requirements of "no fire and no explosion" for thermal runaway protection in GB38031 standard. Utility Model Content

[0005] Technical problem to be solved by the utility model In view of this, one of the objectives of this utility model is to provide a composite protective structure, a power battery box cover, and a power battery. By constructing a power battery box cover jet protection structure based on a high-temperature resistant, impact-resistant, and gradient thermal insulation composite structure, the problem of thermal protection failure of existing silicate-based thermal insulation materials when dealing with thermal runaway jets at ≥800℃ is solved.

[0006] Technical solution and beneficial effects of this utility model The first aspect of this utility model discloses a composite protective structure located between the cover and the battery cell for the protection of the power battery box cover, including an impact-resistant layer and a gradient heat insulation layer stacked on top of the impact-resistant layer; The impact-resistant layer is made of high-temperature resistant metal material or ablation material; The gradient insulation layer includes an aerogel-ceramic fiber composite pad and an intumescent flame-retardant coating. The aerogel-ceramic fiber composite pad has a nanoporous structure, and the intumescent flame-retardant coating can carbonize and expand.

[0007] This technical solution achieves a dual protection mechanism through multi-physics field coupling: during the jet impact stage, the impact-resistant layer uses its material properties to mitigate or resist the high-speed impact of the high-temperature ejected material; during the heat conduction stage, the gradient insulation layer inhibits gas convection heat transfer through the nanoporous structure of the aerogel-ceramic fiber composite pad, and constructs a heat insulation barrier by means of the carbonization reaction of the intumescent flame-retardant coating.

[0008] Furthermore, the impact-resistant layer is made of a high-temperature resistant metal material or an ablation material with a melting point greater than 1000°C.

[0009] Furthermore, the high-temperature resistant metal material of the impact-resistant layer is nickel or steel.

[0010] Furthermore, the high-temperature resistant metal material has a porous structure and is made of foamed nickel or foamed steel.

[0011] Porous foam nickel or foam steel can reduce airflow impact speed while ensuring smooth airflow, and also effectively reduce weight and cost.

[0012] Furthermore, the ablation material of the impact-resistant layer is composed of a matrix material and a filler. The matrix material is one or more of phenolic resin, epoxy resin, and silicone rubber, and the filler is one or more of asbestos fiber, silicon dioxide, and metal oxide.

[0013] The matrix material has good bonding strength and erosion resistance, and the filler has low density and certain reactivity. The ablation material formed by these components can effectively meet the requirements for impact resistance.

[0014] Furthermore, the impact-resistant layer is plate-shaped or block-shaped, and its size covers the injection range of the safety valve.

[0015] In the event of thermal runaway, the safety valve ejects material in a jet-like manner. The requirement can be met by covering the area of ​​the safety valve's ejection with an impact-resistant layer, which can reduce the amount of impact-resistant layer material used, further improve utilization efficiency, and reduce economic costs.

[0016] Furthermore, the impact-resistant layer and the gradient heat insulation layer are bonded together with a high-temperature resistant adhesive.

[0017] High-temperature resistant adhesives have advantages such as high bonding strength, good sealing performance, and corrosion resistance, and are easy to use.

[0018] Furthermore, the gradient heat insulation layer is tightly bonded to the cover, and there is a predetermined gap between the impact-resistant layer and the battery cell.

[0019] There is a predetermined gap between the impact-resistant layer and the battery cell, which can ensure a certain amount of venting space and achieve smooth venting.

[0020] The second aspect of this utility model also relates to a power battery box cover, including a cover body and the aforementioned composite protective structure.

[0021] Because of the aforementioned composite protective structure, the battery box cover can effectively prevent damage caused by thermal runaway, thus improving its applicability.

[0022] A third aspect of this utility model also relates to a power battery, including a battery cell and the aforementioned power battery cover, wherein the gap between the power battery cover and the battery cell is between 2-20 mm.

[0023] Because of the aforementioned composite protection structure, this power battery can effectively prevent damage caused by thermal runaway, thus improving product performance.

[0024] In addition to the purposes, features, and effects described above, this utility model has other purposes, features, and effects. The present utility model will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0025] Figure 1 This is an exploded view of the composite protective structure according to an embodiment of the present invention; Figure 2 This is a three-dimensional schematic diagram of the composite protective structure according to an embodiment of the present utility model; Figure 3 This is a front view schematic diagram of the composite protective structure according to an embodiment of the present utility model.

[0026] The following are the labels in the diagram: 1. Cover, 2. Gradient insulation layer, 3. Impact-resistant layer, 4. Battery cell, 5. Safety valve. Detailed Implementation

[0027] To enable those skilled in the art to better understand this technical solution, the technical solution of this utility model will be clearly and completely described below in conjunction with the accompanying drawings and embodiments.

[0028] The structures, proportions, and sizes illustrated in the accompanying drawings are merely for illustrative purposes and are not intended to limit the scope of this invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of this invention, should still fall within the scope of the disclosed technical content. Similarly, terms such as "front," "back," "upper," "lower," "top," "bottom," "inner," and "outer" used in this specification are merely for clarity and not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this invention.

[0029] Currently, existing power battery box cover protection technologies are mainly based on silicate mineral thermal insulation treatment. When the temperature exceeds 700℃, high-speed ejected material will break through the thermal insulation layer, making it difficult to meet the "no fire, no explosion" requirements for thermal runaway protection. To address the above problems, the basic idea of ​​this utility model is to construct a power battery box cover jet protection structure based on a high-temperature resistant, impact-resistant, gradient thermal insulation composite structure, which solves the problems of material brittleness, particle penetration, and thermal protection failure of existing silicate-based thermal insulation materials when dealing with thermal runaway jets at ≥800℃.

[0030] refer to Figures 1 to 3 As shown, a composite protective structure of this utility model embodiment is located between the cover 1 and the battery cell 4 for the protection of the power battery box cover 1, including an impact-resistant layer 3 and a gradient heat insulation layer 2 stacked on top of the impact-resistant layer 3. The impact-resistant layer 3 is made of high-temperature resistant metal or ablation material and is used to mitigate or resist the impact of high-temperature ejected material. The gradient insulation layer 2 comprises an aerogel-ceramic fiber composite pad and an intumescent flame-retardant coating. The aerogel-ceramic fiber composite pad has a nanoporous structure, and the intumescent flame-retardant coating can carbonize and expand. The nanoporous structure suppresses gas convective heat transfer, and the carbonization and expansion reaction of the coating constructs an insulation barrier. The pore size of the nanoporous structure is typically between 20-50 nm, within which the effect of suppressing gas convective heat transfer is relatively good. The insulation material can also be made of other low-density flexible materials, as long as they meet the requirements of gradient insulation.

[0031] A dual protection mechanism is achieved through multi-physics coupling: during the jet impact stage, the impact-resistant layer uses its material properties to mitigate or resist the impact of high-temperature ejected material; during the heat conduction stage, the gradient insulation layer inhibits gas convection heat transfer through the nanoporous structure of the aerogel-ceramic fiber composite pad, and constructs a heat insulation barrier by means of the carbonization reaction of the intumescent flame-retardant coating.

[0032] Preferably, the impact-resistant layer 3 is made of a high-temperature resistant metal material or an ablation material with a melting point greater than 1000°C. High-temperature resistant metal materials such as nickel, steel, or other high-temperature resistant metal materials are not limited here.

[0033] Specifically, the high-temperature resistant metal material of the impact-resistant layer 3 has a porous structure and is made of foamed nickel or foamed steel.

[0034] Porous foam nickel or foam steel can reduce airflow impact velocity while ensuring smooth airflow passage, and may also effectively reduce weight and lower economic costs.

[0035] In addition, the impact-resistant layer 3 can also be made of an ablation material. In some embodiments, the ablation material of the impact-resistant layer 3 consists of a matrix material and a filler, wherein the matrix material is one or more of phenolic resin, epoxy resin, and silicone rubber, and the filler is one or more of asbestos fiber, silica, and metal oxide.

[0036] The matrix material has good bonding strength and erosion resistance. Erosion resistance refers to the material's ability to resist surface damage when subjected to high-speed airflow impact. The filler has low density and a certain degree of reactivity. Reactivity means that the filler can undergo chemical reactions or physical interactions with other substances. The resulting ablation material can effectively meet the impact resistance requirements.

[0037] In some embodiments, the impact-resistant layer 3 is plate-shaped or block-shaped, and its size covers the spray range of the safety valve 5; the thickness is usually 1-20mm, and the specific size is determined according to factors such as the thermal runaway characteristics of the battery cell and cost.

[0038] In the event of thermal runaway, the ejected material from the safety valve is usually jet-shaped. The requirement can be met by covering the area of ​​the safety valve ejection with an impact-resistant layer, which can reduce the amount of impact-resistant layer material used, further improve utilization efficiency, and reduce costs.

[0039] In some embodiments, the impact-resistant layer 3 and the gradient heat insulation layer 2 are bonded together by a high-temperature resistant adhesive. The high-temperature resistant adhesive has advantages such as high bonding strength, good sealing performance, and corrosion resistance, and is easy to use.

[0040] Preferably, the gradient heat insulation layer 2 and the cover 1 are closely fitted together, making them more compact and saving energy; while there is a predetermined gap between the impact-resistant layer 3 and the battery cell 4, usually between 2-20mm, which provides ventilation space and enables smooth ventilation.

[0041] This protective structure can block high-temperature, high-speed solid ejections when thermal runaway occurs in the battery cell, reduce the impact speed of high-speed airflow, isolate the thermal impact of high-temperature ejections on the cover, and prevent the cover from melting and breaking down under the dual effects of high temperature and high-speed impact, which could lead to battery pack fire, thus greatly improving the overall safety of the battery pack.

[0042] The second aspect of this utility model also relates to a power battery box cover, including a cover body 1 and the aforementioned composite protective structure.

[0043] Because of the aforementioned composite protective structure, the battery box cover can effectively prevent damage caused by thermal runaway, thus improving its applicability.

[0044] The third aspect of this utility model also relates to a power battery, including a battery cell 4 and the aforementioned power battery cover, wherein the gap between the power battery cover and the battery cell 4 is between 2-20 mm.

[0045] Because of the aforementioned composite protection structure, this power battery can effectively prevent damage caused by thermal runaway, thus improving product performance.

[0046] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. If any person skilled in the art, inspired by this description, designs a similar structure to the present invention without departing from its inventive spirit, such design shall fall within the protection scope of the present invention.

Claims

1. A composite protective structure, located between the cover (1) and the battery cell (4), for protecting the cover (1) of a power battery box, characterized in that, It includes an impact-resistant layer (3) and a gradient insulation layer (2) stacked on top of the impact-resistant layer (3); The impact-resistant layer (3) is made of high-temperature resistant metal material or ablation material; The gradient insulation layer (2) includes an aerogel-ceramic fiber composite pad and an intumescent flame-retardant coating. The aerogel-ceramic fiber composite pad has a nanoporous structure, and the intumescent flame-retardant coating can carbonize and expand.

2. The composite protective structure according to claim 1, characterized in that, The impact-resistant layer (3) is made of high-temperature resistant metal material or ablation material with a melting point greater than 1000℃.

3. The composite protective structure according to claim 2, characterized in that, The high-temperature resistant metal material of the impact-resistant layer (3) is nickel or steel.

4. The composite protective structure according to claim 3, characterized in that, The high-temperature resistant metal material of the impact-resistant layer (3) has a porous structure and is made of foamed nickel or foamed steel.

5. The composite protective structure according to claim 2, characterized in that, The ablation material of the impact-resistant layer (3) is composed of a matrix material and a filler. The matrix material is one or more of phenolic resin, epoxy resin, and silicone rubber, and the filler is one or more of asbestos fiber, silicon dioxide, and metal oxide.

6. The composite protective structure according to claim 2, characterized in that, The impact-resistant layer (3) is plate-shaped or block-shaped, and its size is sufficient to cover the spray range of the safety valve (5).

7. The composite protective structure according to claim 1, characterized in that, The impact-resistant layer (3) and the gradient heat insulation layer (2) are bonded together with high-temperature resistant adhesive.

8. The composite protective structure according to claim 1, characterized in that, The gradient heat insulation layer (2) is tightly bonded to the cover (1), and there is a predetermined gap between the impact-resistant layer (3) and the battery cell (4).

9. A power battery box cover, characterized in that, It includes a cover (1) and a composite protective structure as described in any one of claims 1 to 8.

10. A power battery, characterized in that, It includes a battery cell (4) and a power battery box cover as described in claim 9, wherein the gap between the power battery box cover and the battery cell (4) is between 2 and 20 mm.

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