Multi-layer functional composite battery cell heat insulation sheet and preparation method thereof
By designing a multi-layered functional composite cell heat shield, it integrates synergistic defense functions such as resistance to mechanical shock, absorption of latent heat, reflection of radiant heat, and blocking of heat conduction. This solves the problem of structural damage and functional failure of the cell heat shield during thermal runaway, thereby improving the thermal safety of the battery system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-02-09
- Publication Date
- 2026-05-08
AI Technical Summary
Existing battery cell insulation sheets, due to their simple structure and isolated function, cannot effectively resist explosive thermal shock and high-intensity radiant heat during thermal runaway, resulting in structural damage and failure of insulation function.
The multi-layer functional composite cell heat insulation sheet structure consists of a first fiber-reinforced phase change layer, a first reflective layer, a first heat insulation layer, a second reflective layer, a second heat insulation layer, a third reflective layer, and a second fiber-reinforced phase change layer from top to bottom. Through the symmetrical alternating structure of fiber-reinforced phase change layer-reflective layer-heat insulation layer, it achieves synergistic defense against mechanical impact, absorption of latent heat, reflection of radiant heat, and blocking of conduction.
Maintaining structural integrity and functional continuity under extreme thermal shock, improving the thermal safety threshold of the battery system, preventing aerogel brittle fracture, and achieving integrated defense from mechanical protection to active thermal buffering.
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Abstract
Description
Technical Field
[0001] This invention relates to a heat insulation sheet for battery cells and its preparation method. Background Technology
[0002] With the widespread application of lithium-ion batteries in new energy vehicles and energy storage, the safety problem of chain thermal propagation caused by thermal runaway is becoming increasingly serious. Therefore, setting up efficient heat insulation sheets between battery cells has become crucial to improving the safety of battery systems. Currently, the technological development of cell heat insulation sheets mainly revolves around improving basic heat insulation performance. Existing technical solutions can be roughly divided into three categories: First, using aerogels (such as silica and ceramic fiber aerogels) as the core heat insulation material to achieve static heat insulation through their extremely low thermal conductivity; second, composite flame-retardant layers (such as mica and fiberglass cloth) or encapsulation layers (such as PET film) on the heat insulation core material to improve fire resistance and structural integrity; and third, attempting to introduce phase change materials to delay temperature rise through latent heat absorption. However, the above-mentioned existing technologies still have significant shortcomings, especially in dealing with the extreme, dynamic, and explosive thermal shock generated during thermal runaway. The lack of structural functionality is a common defect, and most solutions only focus on a single dimension of "heat insulation". When the battery cell explodes, the shock wave and high-speed jet generated will first act on the surface of the heat insulation sheet. The porous aerogel layer in the existing structure is very easy to break and pulverize, causing the porous heat insulation structure on which it depends to be physically destroyed in an instant, and the heat insulation function will quickly fail.
[0003] In summary, current designs for battery cell insulation sheets are mostly based on steady-state or slow-heating conditions. Their simple structure and isolated functional layers make it difficult to form an effective protective loop in the extreme instant of thermal runaway. Once the first physical defense (impact resistance) is breached, the subsequent heat insulation and heat absorption functions become useless. Summary of the Invention
[0004] The present invention aims to solve the technical problem that existing battery cell heat insulation sheets, due to their simple structure and isolated function, cannot effectively resist the instantaneous explosive thermal shock and high-intensity radiant heat caused by thermal runaway, which easily leads to structural damage and immediate failure of the heat insulation function. The present invention provides a multi-layer functional composite battery cell heat insulation sheet and its preparation method.
[0005] The multilayer functional composite battery cell heat insulation sheet of the present invention is composed of, from top to bottom, a first fiber-reinforced phase change layer, a first reflective layer, a first heat insulation layer, a second reflective layer, a second heat insulation layer, a third reflective layer, and a second fiber-reinforced phase change layer.
[0006] The preparation method of the multilayer functional composite battery cell heat insulation sheet of the present invention is carried out according to the following steps:
[0007] S1. Preparation of composite layer preform: The silicone resin-phase change composite slurry is uniformly coated on the upper and lower surfaces of the glass fiber cloth, and then the reflective layer is immediately attached to the wet glass fiber cloth surface. After heating and drying, the fiber-reinforced phase change layer-reflective layer preform is obtained.
[0008] S2. Layered assembly: The fiber-reinforced phase change layer-reflective layer preform, the first heat insulation layer, the second heat insulation layer, and the fiber-reinforced phase change layer-reflective layer preform are stacked alternately in the structural order to obtain a multi-layer structure;
[0009] S3. Overall packaging: The multi-layer structure stacked in S2 is placed in the packaging film, and the layers are tightly bonded by hot pressing or vacuum packaging to obtain the cell heat insulation sheet.
[0010] This invention proposes a novel multilayer functional composite cell heat shield, whose layer structure can achieve synergistic defense against different stages and heat transfer modes in the thermal runaway chain reaction, from resisting mechanical shock, absorbing latent heat, blocking conduction and reflecting radiant heat, thereby maintaining structural integrity and continuous function under extreme thermal shock, fundamentally improving the thermal safety threshold of the battery system.
[0011] This invention, through its unique symmetrical alternating structure of "fiber-reinforced phase change layer - reflective layer - heat insulation layer", integrates for the first time in a prototype a synergistic defense function that resists mechanical shock, absorbs latent heat of phase change, reflects radiant heat, and blocks heat conduction. It fundamentally solves the industry problem that existing battery cell heat insulation sheets cannot resist the instantaneous explosive thermal shock of thermal runaway due to their simple structure and isolated function.
[0012] The outermost fiber-reinforced phase change layer of this invention resists explosive impact through a glass fiber cloth skeleton, preventing the internal aerogel from brittlely breaking; at the same time, the encapsulated phase change material can quickly absorb a large amount of latent heat, realizing integrated defense from mechanical protection to active thermal buffering, solving the fundamental problem that traditional heat insulation sheets suffer structural damage and immediate functional failure under instantaneous thermal shock. Detailed Implementation
[0013] Specific implementation method one: This implementation method is a multilayer functional composite battery cell heat insulation sheet, which is composed of a first fiber-reinforced phase change layer, a first reflective layer, a first heat insulation layer, a second reflective layer, a second heat insulation layer, a third reflective layer, and a second fiber-reinforced phase change layer from top to bottom.
[0014] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the first fiber-reinforced phase change layer and the second fiber-reinforced phase change layer have the same structure, both consisting of glass fiber cloth and an organosilicon resin-phase change composite coating coated and cured thereon. Everything else is the same as in Specific Implementation Method One.
[0015] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 2 in that the organosilicon resin-phase change composite coating is composed of the following components by weight: 10-20 parts organosilicon resin, 5-20 parts epoxy resin, 1-5 parts curing agent, 10-60 parts phase change material, and 40-60 parts anhydrous ethanol. Everything else is the same as in Specific Implementation Method 2.
[0016] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the phase change material is one or a mixture of several of the following: calcium chloride hexahydrate, magnesium chloride hexahydrate, sodium sulfate decahydrate, gypsum, sodium acetate, and sodium polyacrylate. Everything else is the same as in Specific Implementation Methods One to Three.
[0017] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that the first reflective layer, the second reflective layer, and the third reflective layer are all metal foils or vacuum-deposited metal films, and the material is one or a mixture of silver, aluminum, copper, or steel. Everything else is the same as in Specific Implementation Method Four.
[0018] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that both the first and second heat insulation layers are aerogel heat insulation layers, made of silica aerogel, ceramic fiber felt, or ceramic fiber paper. Everything else is the same as in Specific Implementation Method Five.
[0019] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that: the thickness of the first and second heat insulation layers is 0.5mm~1mm; the thickness of the first and second fiber-reinforced phase change layers is 0.2mm~0.4mm; and the thickness of the first, second, and third reflective layers is 0.012mm~0.015mm. Everything else is the same as in Specific Implementation Method Six.
[0020] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the outer side of the multilayer functional composite battery cell heat insulation sheet is further encapsulated by an encapsulation film, which can be a PET film, a PI film, or an aluminum-plastic film. Everything else is the same as in Specific Implementation Method Seven.
[0021] Specific Implementation Method Nine: This implementation method is the preparation method of the multilayer functional composite battery cell heat insulation sheet in Specific Implementation Method Eight, and is carried out according to the following steps:
[0022] S1. Preparation of composite layer preform: The silicone resin-phase change composite slurry is uniformly coated on the upper and lower surfaces of the glass fiber cloth, and then the reflective layer is immediately attached to the wet glass fiber cloth surface. After heating and drying, the fiber-reinforced phase change layer-reflective layer preform is obtained.
[0023] S2. Layered assembly: The fiber-reinforced phase change layer-reflective layer preform, the first heat insulation layer, the second heat insulation layer, and the fiber-reinforced phase change layer-reflective layer preform are stacked alternately in the structural order to obtain a multi-layer structure;
[0024] S3. Overall packaging: The multi-layer structure stacked in S2 is placed in the packaging film, and the layers are tightly bonded by hot pressing or vacuum packaging to obtain the cell heat insulation sheet.
[0025] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Nine in that the composite slurry coating in S1 is applied using a doctor blade coating, roller coating, or slot extrusion coating method. Everything else is the same as in Specific Implementation Method Nine.
[0026] The invention was verified using the following experiments:
[0027] Experiment 1: This experiment is a multilayer functional composite cell heat insulation sheet, which is composed of a first fiber-reinforced phase change layer, a first reflective layer, a first heat insulation layer, a second reflective layer, a second heat insulation layer, a third reflective layer, and a second fiber-reinforced phase change layer from top to bottom;
[0028] The first fiber-reinforced phase change layer and the second fiber-reinforced phase change layer have the same structure, both consisting of glass fiber cloth (0.2 mm thick) and an organosilicon resin-phase change composite coating coated and cured thereon.
[0029] The organosilicon resin-phase change composite coating is composed of the following components by weight: 15 parts organosilicon resin, 10 parts epoxy resin, 2 parts amine curing agent, 20 parts phase change material, and 40 parts anhydrous ethanol.
[0030] The phase change material is magnesium chloride hexahydrate;
[0031] The first, second, and third reflective layers are all aluminum foil with a thickness of 0.015 mm.
[0032] The first and second insulation layers are both aerogel insulation layers made of aluminum silicate fiber paper with a thickness of 0.5 mm.
[0033] The outer side of the multi-layer functional composite cell heat insulation sheet also needs to be covered and encapsulated by an encapsulation film, which is an aluminum-plastic film.
[0034] The above-mentioned method for preparing the multilayer functional composite battery cell heat insulation sheet is carried out according to the following steps:
[0035] S1. Preparation of composite layer preform: Mix 15 parts of silicone resin, 10 parts of epoxy resin, 2 parts of amine curing agent, 20 parts of phase change material and 40 parts of anhydrous ethanol into a slurry. Then, use a scraper to evenly coat the slurry onto the upper and lower surfaces of the glass fiber cloth. Immediately afterwards, attach the reflective layer to the wet glass fiber cloth surface and dry and cure at 80°C to obtain an integrated fiber-reinforced phase change layer-reflective layer preform.
[0036] S2. Layered assembly: The fiber-reinforced phase change layer-reflective layer preform, the first heat insulation layer, the second heat insulation layer, and the fiber-reinforced phase change layer-reflective layer preform are stacked alternately in the structural order to obtain a multi-layer structure;
[0037] S3. Overall packaging: The multi-layer structure stacked in S2 is placed in an aluminum-plastic film and vacuum-sealed to tightly bond the layers, resulting in a cell heat insulation sheet.
[0038] Experiment 2: The difference between this experiment and Experiment 1 is that the organosilicon resin-phase change composite coating is composed of the following components by weight: 15 parts organosilicon resin, 10 parts epoxy resin, 2 parts amine curing agent, 40 parts phase change material, and 40 parts anhydrous ethanol. Everything else is the same as in Experiment 1.
[0039] Experiment 3: The difference between this experiment and Experiment 2 is that both the first and second insulation layers are aerogel insulation layers made of mullite fiber felt with a thickness of 0.5 mm. Everything else is the same as Experiment 2.
[0040] Comparative Example 1: This experiment demonstrates a method for preparing a battery cell heat insulation sheet, specifically carried out according to the following steps:
[0041] S1. Preparation of composite layer preform: Mix 15 parts of silicone resin, 20 parts of epoxy resin, 5 parts of amine curing agent, 40 parts of phase change material and 40 parts of anhydrous ethanol into a slurry. Then, use a scraper to evenly coat the slurry onto the upper and lower surfaces of a 1 mm thick aluminum silicate fiber paper. Dry and cure at 80°C to obtain a 1.5 mm thick fiber paper phase change layer.
[0042] S2. Encapsulation: The fiber paper phase change layer prepared in S1 is placed in an aluminum-plastic film and vacuum-encapsulated to tightly bond the layers, thus obtaining the cell heat insulation sheet.
[0043] Comparative Example 2: A 1.5mm thick mullite fiber felt was placed in an aluminum-plastic film and vacuum-sealed to tightly bond the layers, thus obtaining a battery cell heat insulation sheet.
[0044] Thermal insulation performance tests were conducted using multilayer functional composite battery cell thermal insulation sheets prepared in Experiments 1-3, as well as those prepared in Comparative Examples 1 and 2. The test samples measured 100mm × 100mm × 1.5mm. Thermocouples were attached to the top and bottom surfaces of the samples with tape to measure the hot and cold surface temperatures. An alcohol torch was ignited to begin heating. Once the flame temperature stabilized at 900℃, the test samples were quickly placed on an iron stand, and timing began. After maintaining this temperature for 5 minutes, the hot surface temperature (facing the flame) and the cold surface temperature (facing away from the flame) of each sample were recorded. The thermal insulation temperature difference was calculated; a higher thermal insulation temperature difference indicated better thermal insulation performance.
[0045] The test results are shown in the table below:
[0046]
[0047] As can be seen from the table above, under the same thermal conditions, comparing the temperature difference between the hot and cold surfaces, the thermal insulation effect of the multilayer functional composite cell thermal insulation sheet prepared by the present invention is better than that of the single-component cell thermal insulation sheet of the same thickness (Comparative Examples 1 and 2).
Claims
1. A multi-layer functional composite battery cell heat insulation sheet, characterized in that... The multi-layer functional composite battery cell heat insulation sheet is composed of a first fiber-reinforced phase change layer, a first reflective layer, a first heat insulation layer, a second reflective layer, a second heat insulation layer, a third reflective layer, and a second fiber-reinforced phase change layer from top to bottom.
2. The multilayer functional composite cell heat insulation sheet according to claim 1, characterized in that... The first fiber-reinforced phase change layer and the second fiber-reinforced phase change layer have the same structure, both consisting of glass fiber cloth and an organosilicon resin-phase change composite coating coated and cured thereon.
3. The multilayer functional composite cell heat insulation sheet according to claim 2, characterized in that... The organosilicon resin-phase change composite coating is composed of the following components by weight: 10-20 parts organosilicon resin, 5-20 parts epoxy resin, 1-5 parts curing agent, 10-60 parts phase change material, and 40-60 parts anhydrous ethanol.
4. The multilayer functional composite cell heat insulation sheet according to claim 3, characterized in that... The phase change material is one or a mixture of several of the following: calcium chloride hexahydrate, magnesium chloride hexahydrate, sodium sulfate decahydrate, gypsum, sodium acetate, and sodium polyacrylate.
5. The multilayer functional composite cell heat insulation sheet according to claim 1, characterized in that... The first, second, and third reflective layers are all metal foils or vacuum-deposited metal films, and the material is one or a mixture of silver, aluminum, copper, or steel.
6. The multilayer functional composite cell heat insulation sheet according to claim 1, characterized in that... The first and second insulation layers are both aerogel insulation layers, made of silica aerogel, ceramic fiber felt, or ceramic fiber paper.
7. A multilayer functional composite cell heat insulation sheet according to claim 1, characterized in that... The thickness of the first and second heat insulation layers is 0.5mm to 1mm; the thickness of the first and second fiber-reinforced phase change layers is 0.2mm to 0.4mm; and the thickness of the first, second, and third reflective layers is 0.012mm to 0.015mm.
8. The multilayer functional composite cell heat insulation sheet according to claim 1, characterized in that... The outer side of the multi-layer functional composite battery cell heat insulation sheet also needs to be covered and encapsulated by an encapsulation film, which is a PET film, PI film, or aluminum-plastic film.
9. The method for preparing a multilayer functional composite battery cell heat insulation sheet as described in claim 4, characterized in that... The preparation method described herein is carried out according to the following steps: S1. Preparation of composite layer preform: The silicone resin-phase change composite slurry is uniformly coated on the upper and lower surfaces of the glass fiber cloth, and then the reflective layer is immediately attached to the wet glass fiber cloth surface. After heating and drying, the fiber-reinforced phase change layer-reflective layer preform is obtained. S2. Layered assembly: The fiber-reinforced phase change layer-reflective layer preform, the first heat insulation layer, the second heat insulation layer, and the fiber-reinforced phase change layer-reflective layer preform are stacked alternately in the structural order to obtain a multi-layer structure; S3. Overall packaging: The multi-layer structure stacked in S2 is placed in the packaging film, and the layers are tightly bonded by hot pressing or vacuum packaging to obtain the cell heat insulation sheet.
10. The method for preparing a multilayer functional composite battery cell heat insulation sheet according to claim 9, characterized in that... The composite slurry coating in S1 is applied using blade coating, roller coating, or slot extrusion.