Flame retardant materials, methods of making and using the same

Abstract

The present invention relates to a flame retardant material comprising: 55-70 wt.% of an alkali silicate condensate; 5-20 wt.% of a metal oxide comprising ZrO2; and a surfactant, wherein the metal oxide is partially co-formed with the alkali silicate condensate into a copolymeric network structure and partially embedded in the form of particles into the copolymeric network structure. The present invention further relates to a method for producing the flame retardant material comprising the steps of: providing a liquid component comprising an aqueous alkali silicate solution; providing a solid component comprising ZrO2 particles, mixing the liquid component with the solid component homogenously and forming a viscous slurry, coating the slurry on a carrier or injecting the slurry into a mold and ventilating and heating to dehydrate and condense and to solidify the slurry to obtain a foamable flame retardant material. The flame retardant material according to the present invention is especially used for stopping the propagation of thermal runaway of power cells.

Description

TECHNICAL FIELD

[0001] The present invention relates to a flame retardant material, a method for preparing the flame retardant material, and the use of the flame retardant material. The flame retardant material is particularly useful for preventing the propagation of thermal runaway of power cells and for protecting power cells from ignition by a high-temperature heat source. The present invention also relates to a battery module or CTP battery pack comprising such a flame retardant material. BACKGROUND

[0002] Lithium batteries are now increasingly widely used in the field of new energy vehicles as power sources. The development trend of lithium battery vehicles is long-range with high power and fast charging. In order to improve the range, the number of lithium batteries and the energy density of the unit cell need to be improved. Due to the pursuit of high energy density in the power battery industry, the battery separator also has a trend of becoming thinner. Although the reduction of the thickness of the separator helps to improve the unit weight density of the cell, it also has a very obvious impact on the safety of the battery. In recent years, due to the pursuit of high energy density in the development of power battery technology, the self-ignition of the battery often occurs after high-power fast charging in actual application scenarios, especially after mechanical collision. The self-ignition of the battery often releases a large amount of heat in a short time and causes thermal runaway due to heat conduction, which can quickly ignite the adjacent battery monomers and eventually ignite the entire battery pack. The entire combustion process often occurs very quickly and releases a large amount of heat, which is difficult to extinguish.

[0003] A mainstream solution at present is to improve the battery management system and introduce thermal insulation materials or flame retardant materials between the battery monomers, so that when a single cell ignites, the heat conduction and thermal runaway between the cells can be slowed down, thereby giving the driver and passengers of the vehicle relatively longer escape time. It is generally accepted that electric vehicles should be able to achieve an escape time of 5 minutes. That is, no severe thermal runaway within the battery pack occurs within 5 minutes after a single cell ignites.

[0004] The widely used thermal insulation material in the prior art is liquid silicone foamed silica gel sheet, which has a temperature resistance range of generally -40°C to 220°C. The foamed silica gel sheet is already in a foamed state, and it is difficult to further foam when it contacts a heat source or burns. In addition, common refractory materials are also used, which mainly contain SiO2 and / or TiO2 and / or Al2O3 and / or ZrO2, etc. The main forms thereof are a coating of refractory paint or a coating of silica gel and modified silica gel. The refractory temperature thereof is between 1200°C and 1700°C. Or a high polymer foamed flame-retardant material is used, a typical example of which is "Telite". The advantages thereof are good flame retardant performance (DIN5510 / BS6853 / GB8624-2012 B level), smooth surface and waterproof and dustproof, good thermal insulation performance, light weight, easy installation, etc. However, the problem thereof is that the temperature resistance thereof is relatively low (less than 200°C). Another disadvantage is that since it is a high polymer material, when the battery cell is in thermal runaway and reaches a high temperature, the high polymer material itself still has the risk of degradation, gas production and burning (http: / / www.pinlue.com / article / 2018 / 03 / 1021 / 545736349040.html).

[0005] Therefore, there is still a strong demand for a flame-retardant material for preventing the spread of thermal runaway of power batteries and protecting power batteries from being ignited by a high-temperature heat source and a flame-retardant member of a battery module made therefrom. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the above-mentioned and / or other defects in the prior art and to provide a novel refractory flame-retardant material which can more effectively retard flames, especially prevent thermal runaway of a battery module.

[0007] The first aspect of the present application provides a flame-retardant material, comprising: 55-70 wt.% of an alkali metal silicate condensate; 5-20 wt.% of a metal oxide containing ZrO2; and a surfactant, wherein the metal oxide partially co-forms a copolymer network structure with the alkali metal silicate condensate and partially embeds in the form of particles in the copolymer network structure.

[0008] The content of the alkali metal silicate condensate is 55-70 wt.%, preferably 55-65 wt.%, more preferably 57-62 wt.%, based on the total weight of the flame-retardant material.

[0009] The content of the metal oxide is 5-20 wt.%, preferably 7-15 wt.%, based on the total weight of the flame-retardant material. In one embodiment, the metal oxide preferably comprises ZrO2 and Al2O3, wherein the weight ratio of ZrO2 to Al2O3 is 1:1-1:5, preferably 1:1.5-1:3, and more preferably 1:2-1:2.7.

[0010] In one embodiment, the flame-retardant material further comprises a carbonate, which is one or more of magnesium carbonate (MgCO3), calcium carbonate (CaCO3), or dolomite (MgCO3-CaCO3). The content of the carbonate is 0.01-5 wt.%, preferably 0.1-4 wt.%, based on the total weight of the flame-retardant material. Since MgCO3 decomposes at 350°C and releases a large amount of CO2 at 700°C, and CaCO3 decomposes and releases CO2 at 825°C, a combination of MgCO3 and CaCO3 or the addition of dolomite (MgCO3-CaCO3) powder can be used to form a temperature gradient of CO2 release. Preferably, the flame-retardant material further comprises graphite. The content of the graphite is 1-20 wt.%, preferably 3-15 wt.%, and more preferably 3-11 wt.%, based on the total weight of the flame-retardant material.

[0011] In one embodiment, the surfactant is one or more of sodium dodecyl benzene sulfonate (SDBS), sodium n-octyl sulfate (SOS detergent), alpha-olefin sulfonate (AOS), fatty alcohol sulfate (FAS), fatty acid methyl ester sulfonate (MES), or fatty alcohol ether sulfate (AES), but is not limited thereto. The content of the surfactant is 0.05-1.2 wt.%, preferably 0.5-1.0 wt.%, based on the total weight of the flame-retardant material. Those skilled in the art can understand that any surfactant commonly used in the art can be used in the present application.

[0012] The flame-retardant material of the present application further comprises free water and crystal water. The content of the free water and crystal water in the flame-retardant material is 17-25 wt.%, preferably 20-22 wt.%, based on the total weight of the flame-retardant material. Among them, the content of the free water is 14-20 wt.%, and the content of the crystal water is 3-5 wt.%, based on the total weight of the flame-retardant material.

[0013] The glass transition interval of the flame-retardant material of the present application is 200-640°C. Preferably, the starting temperature of the glass transition of the flame-retardant material is about 200-220°C. In other words, the flame-retardant material starts to foam at the above-mentioned starting temperature.

[0014] The flame retardant material of the present application can be formed into a self-supporting sheet or a molded piece by a molding process. The molding process can be, for example, coating, injection molding, extrusion, vacuum forming or casting. Such molding processes are well known to those skilled in the art.

[0015] A second aspect of the present application discloses a method for preparing a flame retardant material, comprising the steps of:

[0016] providing a liquid component comprising an aqueous alkali silicate solution,

[0017] providing a solid component comprising ZrO2 particles,

[0018] mixing the liquid component with the solid component homogeneously to form a viscous slurry,

[0019] coating the slurry on a carrier or injecting the slurry into a mold and venting and heating to dehydrate and condense and solidify the slurry to obtain the flame retardant material of the present application.

[0020] In one embodiment, the aqueous alkali silicate solution in the liquid component has a total solids content of 30-50 wt.%, preferably 35-45 wt.%, a modulus of 2.0-2.5, a pH of 11.5-12.5, and a viscosity of 40-50 mPas. The SiO2 content in the alkali silicate ranges from 20-30 wt%, preferably 25 wt%, and the alkali metal is Na and Li, with a molar ratio of 7:1, preferably 6:1.

[0021] In one embodiment, the solid component further comprises SiO2 particles. The pH of the liquid component is adjusted by adding an aqueous alkali hydroxide solution to the liquid component, so that after mixing the liquid component with the solid component, the SiO2 particles in the solid component can exist in the form of an aqueous alkali silicate in the slurry. The aqueous alkali hydroxide can be an aqueous NaOH solution, an aqueous KOH solution, or a combination thereof.

[0022] In one embodiment, the solid component further comprises one or more of Al2O3 particles, TiO2 particles, carbonates, and graphite. In a preferred embodiment, the solid component further comprises Al2O3 particles, carbonates, and graphite. The liquid component further comprises a surfactant selected from one or more of sodium dodecyl benzene sulfonate (SDBS), sodium n-octyl sulfate (SOS detergent), alpha-olefin sulfonate (AOS), fatty alcohol sulfate (FAS), fatty acid methyl ester sulfonate (MES), or fatty alcohol ether sulfate (AES), preferably sodium dodecyl benzene sulfonate.

[0023] In one specific embodiment, the dehydration condensation step of the method for preparing the flame-retardant material of the present application is carried out at a temperature not exceeding 240°C, preferably at 180-200°C. In one preferred embodiment, the dehydration condensation step is carried out at 190°C for 2 hours.

[0024] A third aspect of the present application discloses the use of the flame-retardant material in preparing cell flame-retardant members of a battery module or CTP battery pack, wherein the flame-retardant material is placed in the form of a self-supporting sheet or molded piece between single cells in the battery module or between single cells in the CTP battery pack.

[0025] A fourth aspect of the present application provides a battery module or CTP battery pack comprising the flame-retardant material of the present application or prepared according to the method of the present application. The flame-retardant material can be in the form of a self-supporting sheet or molded piece and is placed between single cells in the battery module or between single cells in the CTP battery pack.

[0026] The flame-retardant material of the present application and the cell flame-retardant members of the battery module or CTP battery pack made therefrom are capable of realizing stepwise foaming corresponding to different temperature intervals during combustion and ceramic sintering reaction at high temperature intervals. The ceramicized flame-retardant material is capable of plugging the broken gap of the thermal runaway battery and fixing its position, so as to control the combustion in a limited area, prevent the thermal runaway of power battery from spreading, and protect the entire power battery from being ignited by high-temperature heat source. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 TG-DSC curve of the flame-retardant material according to one embodiment of the present application is shown;

[0028] Figures 2A-2D Application of the flame-retardant material according to the present application in preventing the spread of thermal runaway in a battery module is shown. DETAILED DESCRIPTION

[0029] The technical features, advantages and implementation modes of the present application will be further described in a clear and understandable manner below by means of description of preferred embodiments and in conjunction with the drawings.

[0030] In one aspect, the present application provides a flame-retardant material comprising: 55-70 wt.% of alkali silicate condensate; 5-20 wt.% of metal oxide comprising Zr02; and a surfactant, wherein the metal oxide partially co-constitutes a copolymerized network structure with the alkali silicate condensate and partially embeds in the form of particles into the copolymerized network structure.

[0031] The basic framework of the fireproof material according to the present application is a silicate condensate forming a network structure. Since the silicate condensate is a material with chemical bond between adjacent units, the fireproof material according to the present application is an entirety, which will not easily scatter or collapse when the battery is on fire. In addition, when zirconium dioxide is added as a structure modifying material in the silicate condensate, Zr enters the network structure of the silicate to form a copolymerized network structure, because the structure modifying material can participate in polymerization, so that the product structure is stronger than that of ordinary fire-resistant coating, which is beneficial to the flowability, surface tension and foaming performance of the fireproof material itself at the glass transition temperature, on the one hand, and on the other hand, it can also make the material have stronger physical and mechanical properties and be more resistant to morphological changes under the conditions of battery fire, high temperature, deformation, gas release and the like.

[0032] Based on the copolymerized network structure as the basic framework, the fireproof material according to the present application has excellent fire-resistant and heat-insulating performance. First, since the fireproof material according to the present application has a hydrate structure, under high temperature conditions, the crystal water will separate and form water vapor, which will absorb and carry away heat, thereby playing a role in reducing temperature. On the other hand, because the glass transition temperature (Tg) of the silicate condensate is about 240°C, the polymer material will soften at high temperature, form a flow body and the surface tension will greatly decrease with the increase of temperature within a certain temperature range, and because of the presence of water vapor and the generation of carbon dioxide by thermal decomposition of the components in the auxiliary material, a large number of bubbles will be generated in the flow body and become a foamed material. This foamed material is a good thermal insulator, which fills the empty space inside the module, thereby covering the thermal runaway battery and its adjacent batteries, blocking air from participating in chemical reactions such as combustion, and the swelling material blocks heat transfer as a good thermal insulator. When maintained at 500°C or above for a relatively long time, the crystal water will gradually be lost, and when the temperature is above 700°C, the remaining silicate condensate structure will sinter and become ceramic. That is, the remaining metal oxides and silicates will together transform into a ceramic material with very dense and hard structure and high temperature resistance. Since it wraps the entire damaged and self-igniting battery, the ceramic material formed will solidify and cover the entire battery, block the leakage of the damaged battery and make it lose activity.

[0033] In a preferred embodiment, the metal oxides in the flame-retardant material according to the application comprise Zr02and Al203. Surprisingly, when zirconium dioxide and aluminum oxide are added simultaneously as structure-modifying materials in a silicate condensate, the resulting flame-retardant material has particularly good product structure, particularly high water content, and a foaming temperature range and a ceramization sintering temperature interval that are particularly suitable for preventing thermal runaway of a battery module. In this case, the network-structured silicate composite material can have the following chemical formula:

[0034] M2O nSi a Zr b Al c O d mH20,

[0035] wherein M is at least one of Li, Na, K, preferably Li and Na, the molar ratio of which is preferably 1 :7;

[0036] 0.5 < a < 1.5, preferably 0.75 < a < 1.25, preferably 0.9 < a < 1.1 ;

[0037] 0.001 < b < 0.009, preferably 0.006 < b < 0.01 ;

[0038] 0.03 < c < 0.1, preferably 0.05 < c < 0.07;

[0039] 0.1 < d < 0.4, preferably 0.15 < d < 0.35, preferably 0.2 < d < 0.3;

[0040] n is 3-6, preferably 4-5;

[0041] m is 6-8, preferably 6.5-7.5.

[0042] In a preferred embodiment, the content of the alkali silicate condensate is 55-70 wt.%, preferably 55-65 wt.%, more preferably 57-62 wt.%, based on the total weight of the flame-retardant material.

[0043] In a preferred embodiment, the content of the metal oxides is 5-20 wt.%, preferably 7-15 wt.%. Preferably, the metal oxides comprise Zr02and Al203; preferably, the weight ratio of Zr02to Al203is 1 : 1 - 1 : 5, preferably 1 : 1.5 - 1 : 3, more preferably 1 : 2 - 1 : 2.7.

[0044] In a preferred embodiment, the fire-retardant material of the present application further comprises a carbonate salt, which can be magnesium carbonate, calcium carbonate, dolomite or a combination thereof. The content of the carbonate salt is 0.01-5 wt.%, preferably 0.1-4 wt.%, more preferably 0.5-2 wt.%, and most preferably 1%, based on the total weight of the fire-retardant material. If the content of the carbonate salt in the fire-retardant material is less than 0.01 wt.%, the effect of high-temperature decomposition to release carbon dioxide cannot be achieved; if the content of the carbonate salt in the fire-retardant material is greater than 5 wt.%, the content of the silicate, metal oxide and graphite will be reduced accordingly, and the satisfactory foaming effect cannot be achieved. Magnesium carbonate decomposes to release carbon dioxide at 350°C, and releases a large amount of CO2 at 700°C, and CaCO3 decomposes to release CO2 at 825°C, thereby achieving the effect of gradient foaming. In another embodiment, a combination of MgCO3 and CaCO3 or the addition of dolomite (MgCO3-CaCO3) powder can be used to form a temperature gradient for the release of CO2, thereby more effectively preventing the battery from burning.

[0045] In another preferred embodiment, the fire-retardant material of the present application further comprises graphite. The content of the graphite is 1-20 wt.%, preferably 3-15 wt.%, and more preferably 3-11 wt.%, based on the total weight of the fire-retardant material. The addition of graphite improves the heat conduction of the fire-retardant material, so that heat can be uniformly distributed inside the fire-retardant material. Graphite can quickly absorb heat during the foaming stage and quickly conduct heat to quickly foam. However, after the material foams, the heat conduction function of graphite is no longer needed. In other words, the role of the foamed material is to insulate heat. If the content of graphite in the fire-retardant material is less than 1 wt.%, the heat conduction effect of the graphite will be discontinuous; if the content of graphite in the fire-retardant material is too high, for example, greater than 20 wt.%, the material will lose the effect of foaming and heat insulation.

[0046] In a particularly preferred embodiment, the flame-retardant material of the present application comprises both a carbonate (e.g. magnesium carbonate) and graphite. In an especially preferred embodiment, the flame-retardant material comprises 5 wt.% graphite and 1 wt.% magnesium carbonate, based on the total weight of the flame-retardant material. In this case, there is a synergistic effect between the components in the flame-retardant material of the present application, which is particularly advantageous for preventing thermal runaway in the battery module. Firstly, the temperature range in which the metal oxide and the foaming material additive magnesium carbonate absorb heat is wider. At the same time, because the material contains multiple foaming materials (free water, crystal water, magnesium carbonate, etc.), the material can achieve the effect of gradient foaming. It should be noted here that the combustion of the battery occurs in stages. Firstly, the electrolyte burns, which is usually at 300-500°C, and then the metal materials in the battery burn in stages, until the temperature rises to 1800°C. Therefore, the flame-retardant material according to the present application is also a material that can match the temperature rise of the battery in stages, so that it can target the battery at each stage by foaming to cool the battery, isolate air and cover the battery to block the flame. On the other hand, if the foaming is concentrated in a narrow temperature range, the material system is likely to be damaged, and the pressure in the module will rise rapidly, causing negative effects. In addition, the presence of graphite can make the heat conduct and distribute uniformly in the material, so that when a cell is ignited, not only the refractory material adjacent to the cell foams, but also the relatively distant material can obtain heat and foam, thereby protecting the cells that are relatively far apart in advance.

[0047] It should be noted that the conventional silica gel flame-retardant material has very low thermal conductivity, which can reduce the heat transfer between the cells. The material of the present application is expected to have relatively high thermal conductivity, and the foamed and expanded material will have relatively low thermal conductivity, thereby blocking the transfer of heat. At the same time, it will cover the cell material and block the transfer of air.

[0048] In a preferred embodiment, the surfactant is sodium dodecyl benzene sulfonate, but is not limited thereto. The content of the surfactant is 0.05-1.2 wt.%, preferably 0.5-1.0 wt%, based on the total weight of the flame-retardant material. Due to the presence of the surfactant, the surface tension of the material decreases more rapidly when the glass transition temperature (Tg) of the material reaches about 240°C, thereby bringing about a more rapid foaming effect.

[0049] In a preferred embodiment, the flame-retardant material of the present application further comprises silicon carbide. Silicon carbide is a high-temperature foaming agent that foams a lot at 800-900°C. This can more advantageously achieve the effect of gradient foaming.

[0050] In a preferred embodiment, the flame retardant material further comprises free water and crystal water, based on the total weight of the flame retardant material. Therein, the content of free water and crystal water in the flame retardant material is 17-25 wt.%, preferably 20-22 wt.%, based on the total weight of the flame retardant material. Therein, the content of free water is 14-20 wt.% and the content of crystal water is 3-5 wt.%, based on the total weight of the flame retardant material.

[0051] In a preferred embodiment, the flame retardant material has a glass transition interval of 200 to 640 °C. The glass transition interval is the range of glass transition temperatures. In the glass transition interval, the surface tension of the flame retardant material decreases significantly and the flowability increases significantly. Preferably, the starting temperature of the glass transition interval of the flame retardant material of the present application is about 200-220 °C.

[0052] In a preferred embodiment, the flame retardant material of the present application is shaped into the form of a self-supporting sheet or a molded part. The shaping method can be, for example, coating, injection molding, extrusion molding, vacuum molding or casting, etc. The shaping method is preferably coating. Such shaping methods are known to the person skilled in the art.

[0053] In another aspect, the present application also relates to a method for preparing a flame retardant material, comprising the following steps:

[0054] - providing a liquid component comprising an aqueous alkali silicate solution,

[0055] - providing a solid component comprising ZrO2 particles,

[0056] - mixing the liquid component with the solid component homogeneously and forming a viscous slurry,

[0057] - coating the slurry on a carrier or injecting it into a mold and ventilating and heating it to dehydrate and condense and solidify to obtain a foamable flame retardant material.

[0058] In a preferred embodiment, the aqueous alkali silicate solution in the liquid component has the following parameters: total solid content of 30-50 wt.%, preferably 35-45 wt.%; preferably, SiO2 content of 20-30 wt%, preferably 25 wt.%; preferably, modulus of 2.0-2.5; preferably, pH of 11.5-12.5; preferably, viscosity of 40-50 mPas.

[0059] In a preferred embodiment, the solid component further comprises Si02 particles, wherein the pH value of the liquid component is adjusted to 11.5 to 12.5 by adding an aqueous alkali metal hydroxide solution, such as an aqueous NaOH solution and / or an aqueous KOH solution, so that the Si02 particles in the solid component are present in the slurry in the form of an aqueous alkali metal silicate after mixing of the liquid component and the solid component. This embodiment is particularly preferred when preparing a flame retardant material having a high silicate content, since it avoids that the liquid component becomes too viscous, which would impede a homogeneous mixing of the liquid component and the solid component.

[0060] In a preferred embodiment, the liquid component or the solid component can comprise a surfactant. Preferably, the liquid component comprises a surfactant. In this way, a homogeneous mixing of the liquid component and the solid component can be facilitated.

[0061] In a preferred embodiment, the solid component further comprises AI2O3 particles, Ti02 particles, one or more of a carbonate (e.g. one or more of magnesium carbonate, calcium carbonate, dolomite), graphite. Preferably, the solid component further comprises AI2O3 particles, one or more of a carbonate (e.g. one or more of magnesium carbonate, calcium carbonate, dolomite), and graphite.

[0062] In a preferred embodiment, the dehydration condensation is carried out at a temperature of not more than 240°C, preferably at 180 to 200°C; preferably, the dehydration condensation is carried out at 190°C for 2 hours.

[0063] It is noted that the improvements and advantages mentioned in connection with the flame retardant material according to the present application also apply to the method according to the present application and vice versa.

[0064] In another aspect, the present application also relates to the use of a flame retardant material according to the present application or prepared by the method according to the present application for stopping the propagation of thermal runaway in a power battery and for protecting a power battery from ignition by a high-temperature heat source, wherein the flame retardant material is placed in the form of a self-supporting sheet or a molded part between single cells within a battery module or between single cells within a CTP battery pack.

[0065] In another aspect, the present application also relates to a battery module or a CTP battery pack comprising a flame retardant material according to the present application or prepared by the method according to the present application, wherein the flame retardant material is placed in the form of a self-supporting sheet or a molded part between single cells within the battery module or between single cells within the CTP battery pack.

[0066] Common power batteries are divided into square batteries, soft package batteries and cylindrical batteries. For these two batteries, they are arranged in order one by one in the module or in the CTP (Cell To Pack) battery. Therefore, a simple method of using the flame-retardant material according to the present application is to first make the material into a reasonable size of a thin sheet shape, and then put it into the module or the battery pack in the form of a sandwich with the battery core. If the cylindrical battery or the square shell with special size and the soft package battery, the material can also be injected into the mold according to the space requirement or the shape requirement, and then dehydrated and condensed into the designed structure shape in the mold, and then equipped into the module or the battery pack.

[0067] The flame-retardant material of the present application can introduce more advantages that ordinary flame-retardant materials do not have, for example:

[0068] The flame-retardant material of the present application can realize a stepped foaming temperature range, so that at different stages of single cell combustion, different flame temperatures can form a stepped stage of foaming;

[0069] Because of the presence of crystal water, in the process of water evaporation, heat can be taken away, and the temperature of the battery pack can be reduced, so as to slow down the speed of thermal runaway;

[0070] In the high temperature zone, the gas produced can be adjusted by adding the proportion of the auxiliary agent, such as magnesium carbonate, so that the gas released in the high temperature stage is not only water, but also carbon dioxide;

[0071] Because of the ceramic sintering reaction of metal oxide materials such as zirconium oxide, titanium oxide and aluminum oxide in the high temperature range, the flame-retardant material of the present application can obtain a fire resistance temperature of more than 2000℃. When the battery core completely loses control (usually reaching 1700-2000℃), it can still not degrade;

[0072] It can provide a more rapid foaming speed. Because of the relatively low glass transition temperature of the material and the rapid production of gas, the material can foam rapidly and cover the adjacent single cell, block the flame contact, air contact and reduce the heat conduction;

[0073] Because of its low glass transition temperature and its low surface tension, the material can foam and spread rapidly, so as to cover and protect the adjacent battery core well;

[0074] It can be sintered into a ceramic. Because the material contains metal oxide and water glass, the material can be sintered into a very heat stable ceramic material under high temperature conditions, and fill and solidify the damaged gap of the thermal runaway battery;

[0075] Because of the presence of graphite material, the material can foam rapidly.

[0076] The composition and the preparation method of the flame retardant material of the present application will be further specifically described below in combination with examples.

[0077] Sample preparation

[0078] Example 1

[0079] Example 1 of the present application is prepared from an aqueous alkali metal silicate solution, ZrO2, Al2O3, TiO2 powder, and a surfactant.

[0080] A. Preparation of raw materials

[0081] 1. Liquid component

[0082] The following components are weighed and mixed uniformly. Take the total weight of the liquid component as 100 g as the basis:

[0083] - 20 g of water;

[0084] - 2 g of NaOH solution (prepared at a concentration of 33%, manufacturer: Sigma-Aldrich);

[0085] - 2 g of KOH solution (prepared at a concentration of 45%, manufacturer: Sigma-Aldrich);

[0086] - 75 g of sodium silicate solution (manufacturer: Sigma-Aldrich; trade name: KENING, model: KN-40A);

[0087] - 1 g of sodium dodecyl benzene sulfonate SDBS (manufacturer: Sigma-Aldrich)

[0088] The total solid content of the liquid component is 40 wt%, the SiO2 content is 25 wt%, the modulus is 2, and the pH is 13 based on the total weight of the composition; the viscosity of the aqueous solution is 29 mPas.

[0089] 2. Solid component

[0090] The following components are weighed and mixed uniformly. Take the total weight of the solid component as 200 g as the basis:

[0091] - 140 g of fused SiO2 powder particles (manufacturer: RW-Fueller; trade name / model: RW Fueller Q1);

[0092] - 10 g of ZrO2 (manufacturer: Langfang Pengcai Surprise Chemical Industry);

[0093] - 40 g of fused Al2O3 powder particles (manufacturer: IMERYS; trade name: Aludor);

[0094] - 10 g of Ti02powder particles (manufacturer: Panzhihua Meiyun Titanium Industry Co., Ltd.; trade name: Ximei Yun MYR-510).

[0095] The bulk density of the solid component was measured to be 440 g / cm3based on GB / T 16913.3-1997 using a bulk density tester (manufacturer: Ji Hangbo Co.; model: HYL-103 natural bulk density meter). 3 .

[0096] B. Preparation method

[0097] The liquid component and the solid component were mixed uniformly at a weight ratio of 1:2 to form a viscous slurry. The slurry was uniformly coated on a surface with a Teflon material as a carrier to form a coated material. The coating thickness was 3 cm. The prepared coated material was passed through a four-stage drying oven at 190 °C with a four-stage oven transmission, and the total drying time was 2 hours. The oven had an auxiliary hot air blowing function. The first stage was a slight wind drying with a wind speed of about 0.1-0.2 m / s, and the drying time was 60 minutes. From the second stage to the fourth stage, it was weak wind drying, and the wind speed gradually increased from 1.0 m / s, 1.5 m / s, to 2.0 m / s, and the drying time was 20 minutes, 20 minutes, and 20 minutes, respectively. Then the dried and cured sheet material was peeled off from the surface of the Teflon base material to form the finally prepared flame-retardant material sheet. In detection or actual use, the prepared flame-retardant material can be cut into the required size according to the needs.

[0098] Example 2

[0099] The flame-retardant composition of Example 2 was prepared using the same liquid component and preparation method as Example 1, except that the composition of the solid component was different.

[0100] The solid component of Example 2 was composed of 140 g of molten Si02, 50 g of Zr02, and 10 g of graphite powder (manufacturer: Zhongnuo New Material; model: 3N-4N; density 1 g / cm3 3 ) based on a total weight of 200 g of the solid component.

[0101] The bulk density of the solid component was measured to be 500 g / cm3based on GB / T 16913.3-1997 using a bulk density tester (manufacturer: Ji Hangbo Co.; model: HYL-103 natural bulk density meter). 3 .

[0102] Examples 3-10

[0103] The flame-retardant compositions of Examples 3-10 were prepared using the same method as Example 1, except that the composition of the solid component was different. The composition of the solid component is shown in Table 1.

[0104] In Example 7, MgCO3 powder was added, in Example 8, dolomite powder was added, in Example 9, CaCO3 powder was added; and in Example 10, SiC powder was added.

[0105] Comparative Examples 1-5

[0106] The flame-retardant compositions of Comparative Examples 1-5 were prepared using the same method as Example 1, except that the composition of the solid component was different. The composition of the solid component is shown in Table 1.

[0107] The solid component of Comparative Example 1 consisted of 210 g of fused SiO2, 5 g of ZrO2, 50 g of fused Al2O3 powder particles, and 5 g of graphite powder, based on a total weight of 270 g of the solid component. The liquid component and the solid component were mixed in a weight ratio of 1 :2.7. The drying temperature was set to 205°C.

[0108] The solid component of Comparative Example 2 consisted of 90 g of fused SiO2, 20 g of ZrO2, and 20 g of fused Al2O3 powder particles, based on a total weight of 130 g of the solid component. The liquid component and the solid component were mixed in a weight ratio of 1 :1.3. The drying temperature was set to 140°C.

[0109] The solid component of Comparative Example 3 consisted of 174 g of fused SiO2, 16 g of fused Al2O3 powder particles, and 10 g of graphite powder, based on a total weight of 200 g of the solid component. The liquid component and the solid component were mixed in a weight ratio of 1 :2.

[0110] The solid component of Comparative Example 4 consisted of 120 g of fused SiO2, 30 g of ZrO2, and 40 g of fused Al2O3 powder particles, and 10 g of graphite powder, based on a total weight of 200 g of the solid component. The liquid component and the solid component were mixed in a weight ratio of 1 :2.

[0111] The solid component of Comparative Example 5 consisted of 180 g of fused SiO2, 5 g of ZrO2, and 5 g of fused Al2O3 powder particles, and 10 g of graphite powder, based on a total weight of 200 g of the solid component. The liquid component and the solid component were mixed in a weight ratio of 1 :2.

[0112] Sample analysis and results

[0113] DSC and TG curves of the prepared samples were recorded with a thermogravimetric analyzer (manufacturer: NETZSCH STA; model: 449F3) to obtain the glass transition onset temperature, glass transition interval, mass loss, crystalline water and free water content of each sample. In addition, the sample was heated with a high temperature muffle furnace and the appearance change of the sample was observed to obtain the foaming time, foaming onset temperature, foaming end temperature, ceramization sintering onset temperature, ceramization completion temperature and refractory temperature.

[0114] 1. Glass transition temperature interval (°C) reflects the temperature interval of material foaming, the larger the glass transition temperature interval, the greater the temperature range in which the battery can be protected from thermal runaway. Moreover, battery thermal runaway is a staged process due to the different ignition points of different components inside the battery. Therefore, a larger foaming temperature interval can stage the process of battery combustion at different thermal runaway stages in a larger range.

[0115] 2. Glass transition onset temperature (°C) reflects the starting temperature of material foaming, if the starting temperature is too low, the battery will start to foam when it is working normally; if the starting temperature is too high, the battery will foam later than the combustion of the battery, and cannot effectively protect the battery from thermal runaway.

[0116] 3. Mass loss (wt.%) reflects the amount of foaming, the greater the mass loss, the better the foaming effect, and vice versa.

[0117] 4. Free water content and crystalline water content (wt.%): The total water content is one of the indicators of the foaming capacity of the material. The continuous release of water vapor can continuously take away heat to cool the flame-retardant material and the battery. Among them, free water can produce water vapor at about 100-300°C, and crystalline water can produce water vapor at a temperature greater than about 300°C. Once the glass transition temperature of 200°C is reached, the material can foam rapidly and a large amount of gas is produced, and there is no time gap.

[0118] 5. Foaming time: The foaming time described herein is the time (seconds) for the flame-retardant material to change from a solid state to a foamed state at a temperature of about 300°C. The shorter the foaming time, the more rapid the mechanism by which the flame-retardant material protects the battery when the battery is on fire. Conversely, if the foaming time is too long, it will not have the effect of preventing heat spread.

[0119] 6. The temperature interval of the foaming onset temperature and the foaming end temperature (°C) is the temperature range in which the material can actually effectively protect the battery.

[0120] 7. Ceramization sintering onset temperature and ceramization sintering completion temperature (°C): describes when the battery temperature is very high, the foamed material will eventually be sintered into a ceramic material, thus filling the voids of the burning cell and sealing the battery. The suitable temperature range for ceramization sintering onset temperature and ceramization sintering completion temperature is 600-900 °C, so that the material can quickly start to convert into a ceramic material when it ends foaming. If the onset temperature is too low, it will affect foaming; if the onset temperature is too high, it will not effectively seal the battery. For example, the melting point of aluminum foil is 660 °C, so the onset temperature is preferably slightly lower than the melting point of aluminum foil. If the completion temperature is too low, it will affect foaming; if the completion temperature is too high, it will also not effectively seal the battery.

[0121] 8. Fire resistance temperature (°C): the fire resistance temperature is the temperature at which the sintered ceramic material does not soften, melt or disintegrate. The higher the fire resistance temperature, the better the fire resistance and refractory performance of the material. For example, in power batteries, copper is an important component of the positive electrode material, with a melting point of about 1084 °C; aluminum is an important component of the negative electrode material and soft package material, with a melting point of about 660 °C; iron is an important material for cylindrical and prismatic cells, with a melting point of about 1535 °C. The fire resistance temperature of the materials described herein is higher than 1700 °C, and in some embodiments, the fire resistance temperature of the material can be higher than 2500 °C.

[0122] 9. Ceramization sintering state indicates the appearance of the material after ceramization is completed. The material described herein forms a hard ceramic-like solid after sintering, thus being able to prevent the burning materials in the battery from spewing out, and the molten metal materials from flowing out.

[0123] The compositions and properties of the fire-resistant materials prepared according to Examples 1-10 and Comparative Examples 1-5 are shown in Table 1 and Table 2 below.

[0124]

[0125]

[0126] From the compositions and properties of the fire-resistant compositions of Examples 1-10 and Comparative Examples 1-5 listed in Table 1 and Table 2, it can be seen that:

[0127] Basic composition and properties of Examples 1-10

[0128] From the calculated compositions, it can be seen that in the fire-retardant materials according to Examples 1-10, the content of alkali silicate ranges from 55 to 70 wt.%, the content of metal oxide ranges from 5 to 20 wt.%, and the metal oxide can only contain Zr02 (Example 2), or can contain Zr02 and Al203 (Examples 3-10), and additionally can contain Ti02 (Example 1). The fire-retardant materials according to the present application can contain graphite (Examples 2-5, 7-10) or can not contain graphite (Examples 1 and 6), and can additionally contain MgC03 (Example 7), dolomite (Example 8), and CaC03 (Example 9) as additional foaming components, and SiC (Example 10). The water content of Examples 1-10 according to the present application is 21-22 wt.%, the foaming start temperature is 200-210°C, the foaming end temperature is 500-800°C, the sintering start temperature for ceramicization is 550-650°C, and the fire resistance temperature is above 1700.

[0129] Comparison of Examples 1-10 with Comparative Examples 1-2

[0130] The weight ratio of liquid component to solid component used in Examples 1-10 of the present application is 1:2.

[0131] In contrast, in the preparation of Comparative Example 1, the weight ratio of liquid component to solid component used is 1:2.7, the drying temperature is 205°C, the alkali silicate content of Comparative Example 1 obtained is 70.7 wt.%, which is higher than the upper limit of 70 wt.% defined in the present application, the water content is as low as 12%, and the foaming temperature range is 310-320°C; while in the preparation of Comparative Example 2, the weight ratio of liquid component to solid component used is 1:1.3, the drying temperature is 140°C, the alkali silicate content of Comparative Example 2 obtained is 49.3 wt.%, which is lower than the lower limit of 55 wt.% defined in the present application, the water content is as high as 35%, and the foaming start temperature is 140°C.

[0132] The excessive amount of solid component as represented by Comparative Example 1 can result in the following negative effects: the mixing of liquid component and solid component and the laying of the material after mixing are very difficult; the water content of the material is too low, resulting in insufficient foaming; and the foaming start temperature is too high, missing the best control point and failing to effectively prevent thermal runaway. The excessive amount of liquid component as represented by Comparative Example 2 can result in the following negative effects: the water content of the material is too high, and the foaming start temperature is too low, so that foaming can start when the battery is normally working; and due to the high water content, the high-voltage insulation is adversely affected.

[0133] Comparison of Examples 1-10 with Comparative Examples 3-5

[0134] The weight ratio of liquid component to solid component used in Comparative Examples 3-5 is 1:2, which is the same as in Examples 1-10.

[0135] Comparative Example 3 does not contain Zr02as required according to the present application. Comparative Examples 4 and 5 have metal oxide contents of 25.4 wt.% and 3.0 wt.% respectively, which exceed the upper and lower limits defined according to the present application.

[0136] The test results show that Examples 1-10 according to the defined content range of the present application have more suitable properties for stopping the propagation of thermal runaway of power batteries than Comparative Examples 3-5 outside the defined content range of the present application, in particular in terms of the foaming temperature interval.

[0137] The glass transition start temperature of Examples 1-10 according to the present application is 200-210°C, which is exactly in the temperature range at which the electrolyte starts to burn, so the flame-retardant material according to the present application is particularly suitable for stopping the propagation of thermal runaway of power batteries. The glass transition start temperature of Comparative Examples 3-5 is significantly too high (250°C) to start foaming immediately in the first phase of the battery thermal runaway process and to block the heat conduction between the battery cells.

[0138] The glass transition interval of Examples 1-10 according to the present application is 200-640°C, which is significantly larger than the glass transition interval of Comparative Examples 3-5 (250-500°C). Therefore, Examples 1-10 according to the present application can suppress the progress of battery burning in different thermal runaway phases in a staged manner over a larger temperature range.

[0139] The amount of substance loss, i.e. the water content, of Examples 1-6 according to the present application, consisting of the free water content and the crystalline water content, is 21-22 wt.%; Examples 7-10 according to the present application have a higher amount of substance loss of 22.3 wt.% due to the additional foaming components, i.e. carbonates and SiC. In contrast, the water content of Comparative Examples 4 and 5 is either too high or too low: the high metal oxide content and the low silicate content in Comparative Example 4 result in a low water content (13 wt.%), which ultimately leads to poor foaming performance and a low amount of foaming; the low metal oxide content and the high silicate content in Comparative Example 5 result in a high water content (27 wt.%), which is advantageous for foaming but has a negative impact on the high-voltage insulation within the battery and is also not advantageous for the corrosion resistance of other materials within the battery pack.

[0140] The foaming time of the graphite-containing examples 2-5 and 7-10 according to the present application at a temperature of 300°C is less than 5 seconds, wherein the foaming time is shortened with increasing graphite content, preferably less than 3 seconds, thus enabling a rapid heat conduction, which means that when a failed cell heats up, not only the material in close proximity to the failed cell can be foamed, but also the material at a distance can be foamed, thus enabling a protection of the whole system from heat conduction. The foaming time of the graphite-free examples 1 and 6 at a temperature of 300°C is much longer (< 30 seconds) and the foaming is not uniform, only partial foaming occurs. It can be concluded that the graphite component is the main factor influencing the foaming speed.

[0141] The foaming temperature interval of examples 1-6 according to the present application is about 210-500°C, examples 7-10 according to the present application have a wider foaming temperature interval due to the additional foaming component, i.e. carbonate and SiC, for example example 10 reaches 215-800°C. In comparison, the foaming temperature interval of comparative examples 3-5 is 260-280°C. It is surprisingly found that the flame retardant material according to the present application has a significantly wider foaming temperature interval compared to example 5 and comparative example 5 having similar composition, thus enabling a protection of the battery in a wider range.

[0142] The ceramization sintering start temperature of examples 1-10 according to the present application is 550°C or 650°C, which matches the typical foaming temperature interval of 210-500°C, thus enabling a ceramization sintering starting after the foaming is essentially finished, thus not affecting the foaming. In addition, the ceramization sintering start temperature is slightly below the melting point of the aluminum foil of 660°C, thus enabling an effective sealing of the battery pores before the aluminum foil melts.

[0143] The fire resistance temperature of examples 1-10 according to the present application is higher than 1700°C, and, in example 2, the fire resistance temperature of the material can be higher than 2500°C. It can be concluded that the flame retardant material according to the present application has a particularly high fire resistance temperature due to the presence of Zr02, thus, when a cell heats up completely out of control (typically 1700-2000°C is reached), degradation does not occur.

[0144] The above results show that the flame retardant material examples 1-10 according to the present application have various performance parameters, i.e. glass transition start temperature, glass transition interval, mass loss, crystallization water and free water content, foaming time, foaming start temperature, foaming end temperature, ceramization sintering start temperature, ceramization completion temperature, and fire resistance temperature, which meet the requirements for battery flame retardation compared to comparative examples 3-5.

[0145] Without wishing to be bound by theory, it is believed that the reason why the flame retardant material according to the present application has the above-mentioned properties is that in the composition of the flame retardant material according to the present application, the metal oxide such as zirconium oxide, especially zirconium oxide and aluminum oxide, forms a copolymerized network structure into the network structure of silicate, thereby favoring the flowability, surface tension and foaming properties of the flame retardant material itself at the glass transition temperature, and due to the copolymerized network structure, the flame retardant material can have stronger physical and mechanical properties and is more resistant to morphological changes under conditions such as battery fire, high temperature, deformation, gas release, etc.

[0146] Preferred examples

[0147] In the examples 1-6 according to the present application, examples 3-6 are preferred. They have a short foaming time of less than 3 seconds, a foaming start temperature of 210°C and a foaming end temperature of 500-510°C.

[0148] Example 1 does not contain graphite and has a long foaming time and uneven foaming.

[0149] Example 2 contains only zirconium oxide as the metal oxide, and the flame retardant material of example 2 is slightly inferior to examples 3-6 containing zirconium oxide and aluminum oxide as the metal oxide, not only in the process but also in the final flame retardant properties. In the process, due to the very high density of the zirconium oxide powder itself, when the solid component is only zirconium oxide, the mixing of the solid component and the liquid component is more difficult to be uniform, so process difficulties will occur. In addition, even if the process difficulties are overcome, the final product density is relatively large, mainly reflected in the foaming speed will be relatively slow. The foaming speed of example 2 is about one to two seconds slower than that of example 3 system, the foaming time is less than 6 seconds, and the foaming start temperature is about 220°C.

[0150] More preferred than the preferred example 4 is the flame retardant material to which an additional foaming component is added, especially the flame retardant material according to example 7. By comparing the flame retardant materials containing (examples 7-10) and not containing (examples 1-6) the additional foaming component, it can be seen that the presence of the additional foaming component such as MgCO3 (example 7), dolomite (example 8) and CaCO3 (example 9) and SiC (example 10) makes the foaming end temperature rise from 500°C of example 6 to 600°C (example 7), and even up to 800°C (example 10), increasing the foaming temperature range, which is conducive to realizing gradient foaming. Among them, magnesium carbonate (example 7) is most preferably used as the additional foaming component, because its foaming end temperature (600°C) is lower than the start temperature of ceramic sintering (650°C), which means that the foaming process has ended when the ceramic sintering process begins, thereby being able to more effectively utilize the additional foaming component.

[0151] Figure 1 Typical TG-DSC curves of the flame-retardant material according to the present invention are shown. The TG curves show that approximately 17 wt.% weight is lost before 300°C, and approximately 5 wt.% weight is lost between 300 and 800°C. Furthermore, the DSC curves show a strong endothermic peak in the temperature range of 300-800°C, which reflects the excellent foaming flame-retardant properties of the flame-retardant material of the present invention within this temperature range.

[0152] Figures 2A-2D The application of the flame-retardant material according to the present invention in a battery module is shown.

[0153] Figure 2A A battery module with flame-retardant material in the form of a self-supporting sheet is shown. Figure 2B The exploded view shows a flame-retardant material in the form of a self-supporting sheet placed between individual cells within a battery module. Figure 2C The diagram illustrates the initial ignition of a single battery cell. At this stage, the flame-retardant material softens, forming a cast body. Its surface tension decreases significantly with increasing temperature. The presence of water vapor and the carbon dioxide produced by the thermal decomposition of additives cause the cast body to generate numerous bubbles, becoming a foaming material. During this process, the evaporation of water vapor carries away heat, slowing the rate of battery temperature rise and extending the time required to trigger thermal runaway. Figure 2D As shown, the foamed material fills the empty space inside the module, thus encapsulating the thermally runaway battery cell and its adjacent cells, preventing air from participating in combustion and other chemical reactions. Simultaneously, the expanded material acts as a good insulator, blocking heat transfer. If the temperature continues to rise above 500℃, on the one hand, the combustion point will be encapsulated, isolating it from air; on the other hand, the remaining silicate condensate structure and metal oxides will sinter and ceramize, preventing the flame from spreading. Because the material encapsulates the entire damaged, spontaneously combusting battery cell, the resulting ceramic material will solidify and encapsulate the entire cell, blocking the leakage points and rendering it inactive.

[0154] The flame-retardant material of the present application has a wider foaming temperature range and stronger structural properties compared with the flame-retardant coating used in the prior art power battery by using a specific proportion of metal oxide as a structural modification material in the silicate condensate. When the battery cell is on fire, the free water in the flame-retardant material will first be separated and form water vapor under high temperature conditions, and at the same time absorb and take away heat. At the same time, the flame-retardant material softens to form a casting body under high temperature, and a large number of bubbles are generated in the casting body due to the presence of water vapor to form a foamed material as a good thermal insulator. On the other hand, due to the presence of graphite as a good thermal conductor, the heat can be quickly conducted within the material system after the flame-retardant material is heated, causing uniform and rapid foaming, and then the foam with thermal insulation properties rapidly fills the empty space in the battery module and between the modules, wrapping and blocking the air. As the battery cell continues to burn, when the temperature continues to rise or is maintained above 500℃ for a long time, the crystal water is gradually lost, and the remaining silicate condensate and metal oxide material is sintered and ceramicized to convert into a solid high-temperature-resistant ceramic material with a very dense and hard structure. In the later stage of the battery cell burning, the sintered ceramic material wrapped around the damaged self-igniting battery cell or filled and plugged the broken opening during the battery cell burning, thereby making the battery cell lose activity and unable to continue to burn. In summary, the flame-retardant material of the present application can sequentially undergo the continuous process of foaming, ceramic sintering after the battery cell is on fire and provide continuous protection for the damaged self-igniting battery cell. The self-ignition of the power battery cell often releases a large amount of heat in a short time, and since the flame-retardant material of the prior art cannot provide continuous state changes, the battery module may have a thermal runaway during the time interval of the state change of the flame-retardant material. In contrast, the flame-retardant material of the present application can provide continuous flame-retardant protection for the damaged self-igniting battery cell, thereby effectively avoiding the spread of thermal runaway of the battery cell and improving the stability and safety of the power battery.

[0155] Although the exemplary embodiments have been described in the foregoing description, it is to be understood that many modifications, substitutions, and changes can be made to the exemplary embodiments without departing from the spirit and scope of this disclosure. For example, the order of the steps recited in the claims can be changed, or omitted. Accordingly, the exemplary embodiments are not to be considered as limited to the precise embodiments described in the foregoing description.

Claims

1. A flame retardant material comprising: - 55-70 wt.% of an alkali silicate condensate, - 5-20 wt.% of a metal oxide, the metal oxide comprising Zr02 and AI2O3, and - a surfactant, wherein the metal oxide partially co-forming a co-polymeric network structure with the alkali silicate condensate and partially embedded in the co-polymeric network structure in the form of particles.

2. The flame retardant material of claim 1, wherein, The content of the alkali silicate condensate is 55-65 wt.% based on the total weight of the flame retardant material.

3. The flame retardant material of claim 2, wherein, The content of the alkali silicate condensate is 57-62 wt.% based on the total weight of the flame retardant material.

4. The flame retardant material of claim 1, wherein, The content of the metal oxide is 7-15 wt.% based on the total weight of the flame retardant material.

5. The flame retardant material of claim 4, wherein, The weight ratio of Zr02 to AI2O3 is 1 : 1-1 :

5.

6. The flame retardant material of claim 5, wherein, The weight ratio of Zr02 to AI2O3 is 1 : 1.5-1 :

3.

7. The flame retardant material of claim 5, wherein, The weight ratio of Zr02 to AI2O3 is 1 : 2-1 : 2.

7.

8. The flame retardant material of claim 1, wherein, The flame retardant material further comprises a carbonate, the carbonate being one or more of magnesium carbonate, calcium carbonate or dolomite, the content of the carbonate being 0.01-5 wt.% based on the total weight of the flame retardant material.

9. The flame retardant material of claim 8, wherein, The content of the carbonate is 0.1-4 wt.% based on the total weight of the flame retardant material.

10. The flame retardant material of claim 1, wherein, The flame retardant material further comprises graphite, wherein the content of graphite is 1-20 wt.% based on the total weight of the flame retardant material.

11. The flame retardant material of claim 10, wherein, The content of graphite is 3-15 wt.% based on the total weight of the flame retardant material.

12. The flame retardant material of claim 10, wherein, The content of graphite is 3-11 wt.% based on the total weight of the flame retardant material.

13. The flame retardant material of claim 1, wherein, The surfactant is one or more of sodium dodecylbenzenesulfonate (SDBS), sodium n-octyl sulfate (SOS detergent), alpha-olefin sulfonate (AOS), fatty alcohol sulfate (FAS), fatty acid methyl ester sulfonate (MES) and / or fatty alcohol ether sulfate (AES), the content of the surfactant being 0.05-1.2 wt.% based on the total weight of the flame retardant material.

14. The flame retardant material of claim 13, wherein, The content of the surfactant is 0.5-1.0 wt.% based on the total weight of the flame retardant material.

15. The flame retardant material of claim 1, wherein, The flame retardant material further comprises free water and crystal water, wherein the content of free water and crystal water in the flame retardant material is 17-25 wt.% based on the total weight of the flame retardant material.

16. The flame retardant material of claim 15, wherein, The content of free water and crystal water in the flame retardant material is 20-22 wt.% based on the total weight of the flame retardant material.

17. The flame retardant material of claim 15, wherein, The content of free water is 14-20 wt.% and the content of crystal water is 3-5 wt.% based on the total weight of the flame retardant material.

18. The flame retardant material according to any one of claims 1-17, wherein, The glass transition temperature interval of the flame retardant material is 200°C to 640°C, the onset temperature of the glass transition of the material being 200°C-220°C.

19. The flame retardant material of claim 18, wherein, The flame retardant material is shaped in the form of a self-supporting sheet or a molded part.

20. A method of making a flame retardant material as claimed in any one of claims 1 to 19 wherein, The method comprises the following steps: - providing a liquid component comprising an aqueous alkali silicate solution, - providing a solid component comprising Zr02 particles and AI2O3 particles, - mixing the liquid component with the solid component homogeneously and forming a viscous slurry, - drying the viscous slurry to form a solid material, and - sintering the solid material to form the flame retardant material. - applying the slurry on a carrier or into a mold and venting and heating it to dehydrate and condense and cure it to obtain a fire-retardant material.

21. The method of claim 20, wherein, The total solids content of the aqueous alkali silicate solution in the liquid component is 30-50 wt.%, the modulus is 2.0-2.5, the pH is 11.5-12.5, and the viscosity is 40-50 mPas; wherein the SiO2 content in the alkali silicate ranges from 20 to 30 wt%.

22. The method of claim 21, wherein, The total solids content of the aqueous alkali silicate solution in the liquid component is 35-45 wt.%.

23. The method of claim 21, wherein, The SiO2 content in the alkali silicate ranges from 25 wt.%.

24. The method of claim 21, wherein, The solid component further comprises SiO2 particles, wherein the pH of the liquid component is adjusted by adding alkali hydroxide to the liquid component, so that after mixing the liquid component and the solid component, the SiO2 particles in the solid component can exist in the slurry in the form of aqueous alkali silicate.

25. The method of claim 24, wherein, The solid component further comprises one or more of TiO2 particles, carbonate, graphite; and the liquid component further comprises a surfactant selected from one or more of sodium dodecyl benzene sulfonate (SDBS), sodium n-octyl sulfate (SOS detergent), alpha-olefin sulfonate (AOS), fatty alcohol sulfate (FAS), fatty acid methyl ester sulfonate (MES), or fatty alcohol ether sulfate (AES).

26. The method of claim 24, wherein, The solid component further comprises carbonate and graphite.

27. The method of any one of claims 20-26, wherein, The dehydration and condensation is carried out at a temperature of no more than 240°C.

28. The method of claim 27, wherein, The dehydration and condensation is carried out at 180-200°C.

29. The method of claim 27, wherein, The dehydration and condensation is carried out at 190°C for 2 hours.

30. Use of the flame-retardant material according to one of claims 1 to 19 for the production of a cell flame barrier of a battery module or CTP battery pack, wherein The fire-retardant material is placed in the form of a self-supporting sheet or a molded piece between single cells within a battery module or between single cells within a CTP battery pack.

31. A battery module or CTP battery pack comprising a flame retardant material according to one of claims 1 to 19 or a flame retardant material prepared according to the method of any one of claims 20-29, wherein, The fire-retardant material is placed in the form of a self-supporting sheet or a molded piece between single cells within a battery module or between single cells within a CTP battery pack.

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