Self-forming packaging material and preparation method therefor and use thereof, and battery potting method

Abstract

The present application belongs to the technical field of packaged batteries, and particularly relates to a self-forming packaging material and a preparation method therefor and the use thereof, and a battery potting method. The self-forming packaging material provided by the present application is prepared from the following raw materials in percentages by mass: 60-80% of an inorganic hydrated salt, 5-15% of deionized water, 5-10% of an acrylic monomer, 0.3-5% of a cross-linking agent, 0.7-5% of a polysaccharide monomer, 2-10% of a moisturizing material, and 1-5% of an initiating material, wherein the moisturizing material comprises lithium chloride and / or calcium chloride. In the present application, the self-forming packaging material has heat absorption capability in the two stages of melting and decomposition; the melting temperature is 20-60ºC, and the heat absorbed during melting is greater than 140 J / g; in the thermal decomposition stage, a chemical reaction occurs at 100-200ºC, heat is actively absorbed, and the heat absorbed during decomposition is greater than 980 J / g; and spontaneous heat absorption is conducted once chemical reaction conditions are reached, forming a continuous heat absorption effect, thereby realizing the thermal management and thermal runaway protection of a battery.

Description

Self-forming packaging material, preparation method and application thereof, and method for encapsulating batteries

[0001] This application claims priority to the Chinese patent application filed with the Patent Office of China on March 27, 2024, with application number CN202410353898.4 and invention name “A self-forming packaging material, its preparation method and application, and method for encapsulating batteries”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the technical field of packaged batteries, and specifically relates to a self-forming packaging material, a preparation method and application thereof, and a method for encapsulating batteries. Background Art

[0003] With the increasing popularity of new energy vehicles, power batteries, as core components of these vehicles, are attracting significant attention for their technological development trends. Battery energy density determines the maximum driving range of electric vehicles and is a key factor influencing battery performance. However, higher energy density can complicate battery pack packaging, increase battery temperature control, and increase the risk of thermal runaway.

[0004] Battery potting technology is a new technology used to address the challenges of battery pack packaging. It involves introducing a mixture of components A and B into the arranged battery pack, allowing the liquid to fill the gaps between the cells and adhere tightly to them. The liquid then solidifies, providing support, fixation, and shock and impact protection. However, the thermal conductivity of battery potting compound is insufficient to effectively control the battery temperature.

[0005] Battery thermal runaway occurs when a battery's internal temperature rises rapidly during use or charging due to factors such as thermal, electrochemical, or mechanical / electrical factors. This rise cannot be effectively controlled or cooled, ultimately leading to serious safety issues such as overheating, combustion, or explosion. In addition to thermal management to prevent thermal runaway by controlling the battery temperature within the normal operating range, post-runaway protection primarily involves using insulation to slow the spread of heat. However, existing insulation materials can only slow the spread of heat, leaving the possibility of heat spreading to adjacent battery packs. Battery thermal runaway can be divided into three stages based on reaction kinetics: internal thermal runaway (90°C–200°C), battery bulging (200°C–350°C), and thermal runaway and explosive failure (350°C–850°C). Suppressing the runaway battery pack temperature within the first stage, controlling it within the initial stages of thermal runaway, is undoubtedly the most effective approach.

[0006] Summary of the Invention

[0007] In view of this, the present application provides a self-forming packaging material, a preparation method and application thereof, and a method for encapsulating batteries. The self-forming packaging material provided in the present application has a two-stage heat absorption capability, which can quickly absorb heat and control the thermal runaway temperature of the battery within 200°C, thereby preventing fire and explosion caused by high temperature.

[0008] In order to solve the above technical problems, the present application provides a self-forming packaging material, comprising the following raw materials in percentage by weight:

[0009] The moisturizing material includes lithium chloride and / or calcium chloride.

[0010] Preferably, the inorganic hydrated salt includes one or more of sodium acetate trihydrate, disodium hydrogen phosphate dodecahydrate, sodium sulfate decahydrate, calcium chloride hexahydrate, ammonium ferric sulfate dodecahydrate, aluminum sulfate 18hydrate, sodium carbonate decahydrate, potassium aluminum sulfate dodecahydrate, sodium thiosulfate pentahydrate, sodium aluminum silicate nonahydrate, sodium silicate pentahydrate, lithium chloride trihydrate, cobalt chloride hexahydrate, copper sulfate heptahydrate, ferrous sulfate heptahydrate, aluminum nitrate nonahydrate and calcium sulfate dihydrate.

[0011] Preferably, the acrylic monomer includes one or more of acrylic acid, sodium acrylate, acrylamide, acrylate, stearic methacrylate, isopropyl acrylamide and hydroxyethyl methacrylate.

[0012] Preferably, the polysaccharide monomers include one or more of alginic acid, sodium alginate, chitosan, starch and pectin.

[0013] Preferably, the cross-linking agent comprises N,N-methylenebisacrylamide.

[0014] Preferably, the initiating material includes one or more of ammonium persulfate, potassium persulfate, hydrogen peroxide, dibenzoyl peroxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate and azobisisobutyronitrile.

[0015] The present application also provides a method for preparing the self-forming packaging material described in the above technical solution, comprising the following steps:

[0016] S1: mixing and melting the inorganic hydrated salt and the first portion of water to obtain solution A;

[0017] S2: dissolving the acrylic acid monomer in the second portion of water and mixing with a cross-linking agent, a polysaccharide monomer, and a moisturizing material for ion cross-linking to obtain a solution B; the moisturizing material comprises lithium chloride and / or calcium chloride;

[0018] S3: mixing the solution B and the solution A to obtain a solution C;

[0019] S4: dissolving the initiating material in the remaining water and mixing it with solution C to obtain the self-forming packaging material.

[0020] Preferably, the melting temperature is 10-20° C. higher than the melting temperature of the inorganic hydrated salt.

[0021] Preferably, the mixing of the solution B and the solution A is performed by adding the solution B into the solution A; during the adding process, the temperature of the system is 5 to 15° C. higher than the melting temperature of the inorganic hydrated salt.

[0022] The present application also provides the use of the self-forming packaging material described in the above technical solution or the self-forming packaging material prepared by the preparation method described in the above technical solution in battery potting.

[0023] The present application also provides a method for encapsulating a battery using the self-forming encapsulation material described in the above technical solution or the self-forming encapsulation material prepared by the preparation method described in the above technical solution, comprising the following steps:

[0024] The batteries to be packaged are arranged in a battery box, and the battery box is filled with self-forming packaging material, sealed, and cured to obtain a packaged battery pack.

[0025] Preferably, the distance between adjacent batteries in the battery box is greater than 0.5 mm.

[0026] Preferably, the curing temperature is 20 to 80° C., and the curing time is 1 to 40 minutes.

[0027] The present application provides a self-forming packaging material, comprising the following raw materials in percentage by weight: 60-80% inorganic hydrated salt, 5-15% water, 5-10% acrylic monomer, 0.3-5% crosslinking agent, 0.7-5% polysaccharide monomer, 2-10% moisturizing material, and 1-5% initiating material; the moisturizing material comprises lithium chloride and / or calcium chloride. In the present application, the self-forming packaging material is in a liquid state before forming, has low viscosity and is easy to flow, and can penetrate various narrow battery gaps; after being acted upon by the initiating material, the liquid material can be initiated by a corresponding initiating means (ultraviolet or high temperature), so that the acrylic monomer and the polysaccharide monomer and the crosslinking agent form a three-dimensional semi-interpenetrating network in the solution, and the hydrophilic groups (carboxyl and / or amino groups) in the monomers are used to restrict the hydrated inorganic salt (through a large number of hydrogen bonds connected to water molecules, the water molecules are restricted in the network. When the ion concentration is high, the water molecules form more hydrogen bonds, and the water absorption performance is relatively strong). After initiation, the material is solid. In the present application, the self-forming packaging material has two stages of heat absorption capacity. In the first stage, before 100°C, the unit heat absorption of the material melting between 20 and 60°C is greater than 140J / g; the unit heat absorption of the material decomposition between 100°C and 200°C is greater than 980J / g. The heat storage capacity of different temperature stages can proceed spontaneously after the temperature is reached, forming a continuous heat absorption effect, thereby realizing thermal management and thermal runaway protection of the battery, controlling the runaway battery in the early stage of temperature runaway, and reducing the risk of thermal runaway. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a DSC graph of the solid self-forming encapsulating material and disodium hydrogen phosphate dodecahydrate (DHPD) prepared in Example 1;

[0029] FIG2 is a schematic diagram of the structure of the arrangement of 18650 lithium-ion batteries in a battery box;

[0030] Figure 3 shows the temperature curves of different battery packs at different detection times;

[0031] FIG4 is a temperature variation curve of different positions of the battery pack of Comparative Example 1 at different detection times;

[0032] FIG5 is a temperature variation curve of different positions of the battery pack of Example 1 at different detection times. DETAILED DESCRIPTION

[0033] The present application provides a self-forming packaging material, comprising the following raw materials in percentage by weight:

[0034] The moisturizing material includes lithium chloride and / or calcium chloride.

[0035] In the present application, the raw materials for preparing the self-forming packaging material include 60-80% of inorganic hydrated salts, preferably 65-70%, by weight percentage. In the present application, the inorganic hydrated salts preferably include one or more of sodium acetate trihydrate, disodium hydrogen phosphate dodecahydrate (DHPD), sodium sulfate decahydrate, calcium chloride hexahydrate, ammonium ferric sulfate dodecahydrate, aluminum sulfate 18hydrate, sodium carbonate decahydrate, potassium aluminum sulfate dodecahydrate, sodium thiosulfate pentahydrate, sodium aluminum silicate nonahydrate, sodium silicate pentahydrate, lithium chloride trihydrate, cobalt chloride hexahydrate, copper sulfate heptahydrate, ferrous sulfate heptahydrate, magnesium sulfate heptahydrate, aluminum nitrate nonahydrate and calcium sulfate dihydrate, more preferably acetate trihydrate. In the present application, the inorganic hydrated salt is preferably sodium acetate trihydrate, disodium hydrogen phosphate dodecahydrate, sodium sulfate decahydrate, calcium chloride hexahydrate, ammonium ferric sulfate dodecahydrate, aluminum sulfate 18hydrate, sodium carbonate decahydrate, potassium aluminum sulfate dodecahydrate, sodium thiosulfate pentahydrate, sodium aluminum silicate nonahydrate, sodium silicate pentahydrate, lithium chloride trihydrate, cobalt chloride hexahydrate, copper sulfate heptahydrate, ferrous sulfate heptahydrate, magnesium sulfate heptahydrate, aluminum nitrate nonahydrate and calcium sulfate dihydrate, more preferably sodium acetate trihydrate, disodium hydrogen phosphate dodecahydrate, sodium sulfate decahydrate or magnesium sulfate heptahydrate. In the present application, when the inorganic hydrated salt includes two or more of the above-mentioned specific substances, the present application has no special requirements for the proportion of the specific substances, and any proportion can be adopted. In the present application, the inorganic hydrated salt is an endothermic material.

[0036] In terms of mass percentage, in the present application, the raw materials for preparing the self-forming packaging material include 5-15% water, preferably 10-12%. In the present application, the water is preferably deionized water.

[0037] In this application, the raw materials for preparing the self-forming packaging material include 5-10% acrylic monomers, preferably 8-10%, by weight percentage. In this application, the acrylic monomers preferably include one or more of acrylic acid, sodium acrylate, acrylamide, acrylate, methacrylate stearate, isopropyl acrylamide, and hydroxyethyl methacrylate, more preferably one of acrylic acid, sodium acrylate, acrylamide, acrylate, methacrylate stearate, isopropyl acrylamide, and hydroxyethyl methacrylate, and even more preferably sodium acrylate, acrylamide, or acrylate. In this application, when the acrylic monomers include two or more of the above-mentioned specific substances, this application has no special requirements for the ratio of the specific substances, and any ratio can be used.

[0038] In this application, the raw materials for preparing the self-forming packaging material include 0.3-5% crosslinking agent, preferably 0.3%, by weight percentage. In this application, the crosslinking agent preferably includes N,N-methylenebisacrylamide.

[0039] In this application, the raw materials for preparing the self-forming packaging material include 0.7-5% polysaccharide monomers, preferably 0.7%, by weight percentage. In this application, the polysaccharide monomers preferably include one or more of alginic acid, sodium alginate, chitosan, starch, and pectin, more preferably one of alginic acid, sodium alginate, chitosan, starch, and pectin, and even more preferably chitosan or starch. In this application, when the polysaccharide monomers include two or more of the above-mentioned specific substances, this application has no special requirements for the ratio of the specific substances, and any ratio can be used.

[0040] In this application, the raw materials used to prepare the self-forming packaging material include 2-10% moisturizing material, preferably 5-7%, by weight percentage. In this application, the moisturizing material includes lithium chloride and / or calcium chloride, preferably lithium chloride or calcium chloride. In this application, when the moisturizing material is lithium chloride and calcium chloride, there are no special requirements for the ratio of lithium chloride and calcium chloride, and any ratio can be used. In this application, the moisturizing material can better lock in moisture, prevent moisture loss in the material, and help maintain the function of the inorganic hydrated salt endothermic material.

[0041] In the present application, the raw materials for preparing the self-forming packaging material include 1 to 5% of an initiating material, preferably 2 to 4%, by weight percentage. In the present application, the initiating material preferably includes one or more of ammonium persulfate, potassium persulfate, hydrogen peroxide, dibenzoyl peroxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, and azobisisobutyronitrile, more preferably one of ammonium persulfate, potassium persulfate, hydrogen peroxide, dibenzoyl peroxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, and azobisisobutyronitrile, and even more preferably ammonium persulfate, potassium persulfate, or ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0042] In the present application, the viscosity of the self-forming encapsulating material before curing is preferably 20 to 3000 cp; the hardness of the solid material obtained after curing of the self-forming encapsulating material is preferably 40 to 400 HC, more preferably 100 to 300 HC.

[0043] In this application, inorganic hydrated salts absorb heat for thermal management and thermal runaway. Acrylic monomers and polysaccharide monomers, under the action of a crosslinker and an initiator, can form a three-dimensional semi-interpenetrating network within the molten hydrated salt. After crosslinking, the material is rendered solid, and the hydrated salt is restricted. Even if the hydrated salt melts above its melting point, the material remains solid and does not flow. The temperature control ability of inorganic hydrated salts is mainly reflected in bound water. Without bound water, there is no heat absorption ability. Adding a moisturizing material can better lock in moisture, prevent water loss, and help maintain the temperature control ability of the inorganic hydrated salt.

[0044] In this application, the self-forming packaging material means that the initial form of the material is liquid, which can fill the gaps between batteries in a fluid manner, and then the liquid solidifies through an in-situ polymerization reaction to form a gel or solid with a certain mechanical strength, which serves as a supporting material for the battery.

[0045] In the present application, the self-forming packaging material has two-stage heat absorption capacity. In the present application, the two-stage heat absorption capacity preferably includes the heat absorption capacity of the first stage material melting and the heat absorption capacity of the second stage material decomposition. In the present application, the melting temperature of the first stage material is preferably 20-60°C, more preferably 26.5-57.6°C; the unit weight heat absorption of melting is preferably >140J / g, more preferably 147.2-171.1J / g; the decomposition temperature of the second stage material is preferably 100-200°C; the unit weight heat absorption of the decomposition of the second stage material is preferably >980J / g, more preferably 983-1565J / g. The self-forming packaging material provided in the present application will spontaneously melt and decompose after reaching the heat absorption temperature, forming a continuous heat absorption effect.

[0046] The present application also provides a method for preparing the self-forming packaging material described in the above technical solution, comprising the following steps:

[0047] S1: mixing and melting the inorganic hydrated salt and the first portion of water to obtain solution A;

[0048] S2: dissolving the acrylic acid monomer in the second portion of water and mixing with a cross-linking agent, a polysaccharide monomer, and a moisturizing material for ion cross-linking to obtain a solution B; the moisturizing material comprises lithium chloride and / or calcium chloride;

[0049] S3: mixing the solution B and the solution A to obtain a solution C;

[0050] S4: dissolving the initiating material in the remaining water and mixing with solution C to obtain the self-forming encapsulating material;

[0051] There is no time sequence restriction for steps S1 and S2.

[0052] In the present application, an inorganic hydrated salt and a first portion of water are mixed and melted to obtain a solution A. In the present application, the mass percentage of the first portion of water to the total mass of water is preferably 10-30%, more preferably 20-25%. In the present application, the function of the first portion of water is to accelerate the melting process of the inorganic hydrated salt.

[0053] In the present application, the melting temperature is preferably 10-20°C higher than the melting temperature of the inorganic hydrated salt. In the present application, the melting is preferably accompanied by stirring. There is no special requirement for stirring in the present application, as long as the melting is complete.

[0054] In this application, an acrylic acid monomer is dissolved in a second portion of water and then mixed with a crosslinker, a polysaccharide monomer, and a moisturizing material for ionic crosslinking to obtain Solution B. In this application, the mass percentage of the second portion of water relative to the total mass of water is preferably 10-60%, more preferably 45-50%. In this application, the dissolution is preferably performed under stirring, and there are no specific requirements for stirring, as long as complete dissolution is achieved.

[0055] In the present application, the mixing is preferably carried out under stirring conditions. The present application has no special requirements for the stirring, as long as the mixing can be uniform.

[0056] In the present application, the ionic crosslinking is that the polysaccharide monomers and acrylic monomers will first undergo ionic crosslinking with the metal cations in the moisturizing material. In the present application, a self-forming encapsulating material prepolymer is obtained through ionic crosslinking.

[0057] After obtaining solution A and solution B, the present application mixes the solution B and solution A to obtain solution C. In the present application, the mixing is preferably adding solution B to solution A. In the present application, the temperature of the system during the addition is preferably 5 to 15°C higher than the melting temperature of the inorganic hydrated salt, more preferably 10°C higher than the melting temperature of the inorganic hydrated salt. In the present application, the addition process is preferably accompanied by stirring. The present application has no special requirements for the stirring, as long as the mixture can be mixed evenly.

[0058] After obtaining solution C, the present application dissolves the initiator material in the remaining water and mixes it with solution C to obtain the self-forming encapsulating material. The present application has no special requirements for the dissolution, as long as it can be completely dissolved. In the present application, the mass concentration of the initiator solution obtained by dissolution is preferably greater than 1%, and more preferably 2-4%. In the present application, the mixing is preferably carried out under stirring conditions. The present application has no special requirements for the stirring, as long as it can be mixed evenly.

[0059] The present application preferably continuously stirs the liquid self-forming packaging material to prevent solidification.

[0060] The present application also provides the use of the self-forming packaging material described in the above technical solution or the self-forming packaging material prepared by the preparation method described in the above technical solution in battery potting.

[0061] The present application also provides a method for encapsulating a battery using the self-forming packaging material described in the above technical solution or the self-forming packaging material prepared by the preparation method described in the above technical solution, comprising the following steps:

[0062] The batteries to be packaged are arranged in a battery box, and the battery box is filled with self-forming packaging material, sealed, and cured to obtain a packaged battery pack.

[0063] In the present application, the battery to be packaged is preferably a lithium-ion battery.

[0064] In the present application, the spacing between adjacent batteries in the battery box is preferably greater than 0.5 mm, and more preferably 1 to 5 mm. This application has no special requirements for the shape and size of the battery box, and it can be designed according to the needs of the battery module. In the present application, the bottom of the battery box is sealed, and the top of the battery box is open or has a top cover with a hole, which is preferably a vent or a filling port.

[0065] In the present application, the flow rate of the self-forming packaging material during the filling process is preferably 0.1 to 2.4 L / min, more preferably 1 to 1.2 L / min. In the present application, the self-forming packaging material can fill all gaps in the battery box during the filling process.

[0066] The present application specifically defines the sealant, and conventional methods in the art may be used.

[0067] In the present application, the temperature for initiating curing is preferably 20-80°C, and the time for initiating curing is preferably 1-40 minutes. The present application preferably determines the curing initiation method based on the type of initiator. The present application can control the curing time by controlling reaction parameters such as reaction temperature, initiator concentration, and ultraviolet light intensity.

[0068] In this application, the cured packaging material preferably has a hardness of 40-100 HC, a tensile strength of 10-300 kPa, and a compressive elastic modulus of 300-3000 kPa. In this application, the cured packaging material can provide support and protection for the battery while also providing thermal management. In this application, the packaged battery pack is capable of multi-stage battery temperature control.

[0069] In order to further illustrate the present application, the technical solutions provided in the present application are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present application.

[0070] Example 1

[0071] The self-forming packaging material includes the following raw materials, calculated by weight percentage: 70% disodium hydrogen phosphate dodecahydrate, 10% deionized water, 8% sodium acrylate, 0.3% N,N-methylenebisacrylamide, 0.7% sodium alginate, 7% calcium chloride, and 4% potassium persulfate.

[0072] The preparation method of the self-forming packaging material is as follows:

[0073] Disodium hydrogen phosphate dodecahydrate was dissolved (with stirring) in a portion of deionized water (accounting for 25% of the total amount of deionized water) at 50° C. to obtain solution A;

[0074] Sodium acrylate was dissolved in a portion of deionized water (accounting for 50% of the total amount of deionized water) under stirring, and then N,N-methylenebisacrylamide, sodium alginate and calcium chloride were added, and the mixture was stirred until completely dissolved and then ion cross-linked to obtain solution B;

[0075] Add solution A to solution B at 50°C (with stirring) and mix well to obtain solution C;

[0076] Potassium persulfate was dissolved in the remaining deionized water and then added (with stirring) to solution C to obtain a liquid self-forming packaging material with a viscosity of 22 cP.

[0077] Example 2

[0078] The self-forming packaging material includes the following raw materials, calculated by weight percentage: 65% sodium acetate trihydrate, 15% deionized water, 8% acrylate, 0.3% N,N-methylenebisacrylamide, 0.7% chitosan, 10% lithium chloride, and 1% ethyl 2,4,6-trimethylbenzoylphenylphosphonate (photoinitiator). 。

[0079] The preparation method of the self-forming packaging material is as follows:

[0080] Dissolve sodium acetate trihydrate (with stirring) in a portion of deionized water (accounting for 25% of the total amount of deionized water) at 70° C. to obtain solution A;

[0081] Dissolve acrylate in a portion of deionized water (accounting for 25% of the total amount of deionized water) under stirring, then add N,N-methylenebisacrylamide, chitosan and lithium chloride, stir until completely dissolved and then perform ionic crosslinking to obtain solution B;

[0082] Add solution A to solution B at 70°C (with stirring) and mix well to obtain solution C;

[0083] Ethyl 2,4,6-trimethylbenzoylphenylphosphonate and the remaining deionized water were mixed and then added (with stirring) to Solution C to obtain a liquid self-forming packaging material with a viscosity of 20 cp.

[0084] Example 3

[0085] The self-forming packaging material includes the following raw materials, calculated by weight percentage: 70% sodium sulfate decahydrate, 12% deionized water, 10% acrylamide, 0.3% N,N-methylbisacrylamide, 0.7% starch, 5% calcium chloride, and 2% ammonium persulfate.

[0086] The preparation method of the self-forming packaging material is as follows:

[0087] Sodium sulfate decahydrate was dissolved (with stirring) in a portion of deionized water (accounting for 25% of the total amount of deionized water) at 50° C. to obtain solution A;

[0088] Dissolve acrylamide in a portion of deionized water (accounting for 50% of the total amount of deionized water) under stirring, then add N,N-methylenebisacrylamide, starch and calcium chloride, stir until completely dissolved, and then perform ionic crosslinking to obtain solution B;

[0089] Add solution A to solution B at 50°C (with stirring) and mix well to obtain solution C;

[0090] Ammonium persulfate was dissolved in the remaining deionized water and then added (with stirring) to Solution C to obtain a liquid self-forming packaging material with a viscosity of 22 cp.

[0091] Example 4

[0092] The self-forming packaging material includes the following raw materials, calculated by weight percentage: 60% magnesium sulfate heptahydrate, 25% deionized water, 7% sodium acrylate, 0.3% N,N-methylbisacrylamide, 0.7% starch, 5% calcium chloride, and 2% ammonium persulfate.

[0093] The preparation method of the self-forming packaging material is as follows:

[0094] Dissolve magnesium sulfate heptahydrate (with stirring) in a portion of deionized water (accounting for 25% of the total amount of deionized water) at 60° C. to obtain solution A;

[0095] Sodium acrylate was dissolved in a portion of deionized water (accounting for 50% of the total amount of deionized water) under stirring, and then N,N-methylenebisacrylamide, sodium alginate and calcium chloride were added, and the mixture was stirred until completely dissolved and then ion cross-linked to obtain solution B;

[0096] Add solution A to solution B at 60°C (with stirring) and mix well to obtain solution C;

[0097] Ammonium persulfate was dissolved in the remaining deionized water and then added (with stirring) to Solution C to obtain a liquid self-forming packaging material with a viscosity of 23 cp.

[0098] Example 5

[0099] A liquid self-forming encapsulation material was prepared according to the method of Example 1, except that the self-forming encapsulation material included the following raw materials: 80% disodium hydrogen phosphate dodecahydrate, 5% deionized water, 5% sodium acrylate, 0.3% N,N-methylenebisacrylamide, 0.7% sodium alginate, 7% calcium chloride, and 2% potassium persulfate. The viscosity of the obtained liquid self-forming encapsulation material was 21 cP.

[0100] Test Example 1

[0101] The liquid self-forming encapsulating materials prepared in Examples 1 to 5 were cured according to the following method and the melting temperature, heat absorption per unit weight of melting, and heat absorption per unit weight of decomposition of the cured solid materials were measured using DSC. The results are listed in Table 1. The DSC procedure is as follows:

[0102] 1. Keep at 0℃ for 1 minute;

[0103] 2. Raise the temperature to 200°C at a rate of 1°C / min;

[0104] 3. Maintain temperature at 200℃ for 1 minute.

[0105] The liquid self-forming packaging materials prepared in Examples 1 and 5 were thermally cured at a temperature of 60°C for 3 minutes to obtain a solid self-forming packaging material; the liquid self-forming packaging material prepared in Example 2 was subjected to a curing reaction at 70°C for 40 minutes using ultraviolet light to obtain a solid self-forming packaging material; the liquid self-forming packaging materials prepared in Examples 3 and 4 were subjected to a curing reaction at a constant temperature of 50°C for 40 minutes using ultraviolet light to obtain a solid self-forming packaging material.

[0106] Table 1 Performance parameters of solid self-forming packaging materials prepared in Examples 1 to 5

[0107] FIG1 is a thermal analysis curve (DSC) diagram of the solid self-forming packaging material prepared in Example 1 and disodium hydrogen phosphate dodecahydrate (DHPD).

[0108] Combining Table 1 and Figure 1, it can be seen that the solid-state self-forming packaging materials prepared in Examples 1-5 exhibit an endothermic peak below 100°C, demonstrating a certain melting heat absorption capacity. The melting temperatures are comparable to those of pure hydrated salts, with no significant impact on the melting temperature of the hydrated salts themselves. A decomposition peak is observed after 100°C. Due to the addition of additional deionized water, the reduction in the decomposition heat absorption rate is significantly reduced compared to the reduction in the melting heat absorption rate, maintaining a high level of heat absorption per unit weight.

[0109] Test Example 2

[0110] The thermal management test of the lithium-ion battery pack was carried out according to the following method; 18650 lithium-ion batteries were used as test objects, three in parallel were connected as a group, and three groups were connected in series for a total of nine batteries, arranged in a crisscross pattern in the battery box, with a distance of 1mm between two adjacent batteries. The battery pack without potting material was used as a bare cell; the liquid self-forming packaging material prepared in Example 1 was filled into the battery box at a rate of 1L / min, and then sealed and cured (60°C, 3min) to obtain a battery pack potted with the self-forming packaging material; the battery box was filled with silicone potting glue (purchased from Shanghai Putai New Materials Technology Co., Ltd.) to obtain a battery pack potted with silicone potting glue as comparative example 1. The center battery temperature at a 3C discharge rate was tested using a thermocouple at different times.

[0111] FIG2 is a schematic structural diagram of the arrangement of batteries in a battery box.

[0112] The results of the maximum temperature of the central battery are listed in Table 2. Figure 3 is a temperature curve diagram of different battery groups at different detection times.

[0113] Table 2 The maximum temperature of the central battery obtained by the test

[0114] It can be seen from Table 2 and Figure 3 that the curve of Example 1 shows a stage with a relatively gentle slope. This is due to the continuous heat absorption of the first endothermic peak, which causes the temperature slope to become gentle. This plays a role in temperature control in the test. The maximum temperature drops from 109°C for the bare cell and 92°C for the potting compound to 54°C. The temperature drops significantly, and the temperature control effect of the self-forming packaging material of Example 1 is significant.

[0115] Test Example 3

[0116] The battery thermal runaway test of the lithium-ion battery pack is carried out according to the following method: the battery arrangement is the same as that of Test Example 2, with 9 batteries arranged in a tic-tac-toe pattern, with materials filled between the batteries, and the positive and negative poles connected by iron sheets to simulate the heat transfer through the iron sheets during thermal runaway of the actual battery pack. After the battery is fully charged, the positive pole faces down and the negative pole faces up. A new energy battery short-circuit needle puncture and extrusion explosion-proof test chamber is used for a needle puncture test. A needle puncture machine is used to pierce the negative pole of the central battery (No. 5) to a depth of 20 mm to induce thermal runaway. A high-temperature thermocouple is pasted in the center of each battery to monitor the temperature changes of each battery.

[0117] The test results are listed in Table 3. FIG4 and FIG5 are temperature change curves of different positions of the battery packs of Comparative Example 1 and Example 1 at different test times, respectively.

[0118] Table 3 Maximum temperatures of the center and surrounding batteries detected

[0119] It can be seen from Table 3 and Figures 4 and 5 that in the thermal runaway test, after the temperature of the runaway battery in Example 1 exceeds 100°C, the surrounding materials continue to absorb heat, suppressing the temperature of the central battery to below 200°C, and the maximum temperature of the surrounding batteries does not exceed 50°C, which is still within the normal operating temperature range of the battery, and has a good thermal runaway protection effect.

[0120] Although the above embodiment provides a detailed description of the present application, it is only a part of the embodiments of the present application, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present application.

Claims

1. A self-forming packaging material, characterized in that Including the following raw materials in percentage by mass: The moisturizing material includes lithium chloride and / or calcium chloride.

2. The self-forming packaging material according to claim 1, characterized in that: The inorganic hydrated salt includes one or more of sodium acetate trihydrate, disodium hydrogen phosphate dodecahydrate, sodium sulfate decahydrate, calcium chloride hexahydrate, ammonium ferric sulfate dodecahydrate, aluminum sulfate 18hydrate, sodium carbonate decahydrate, potassium aluminum sulfate dodecahydrate, sodium thiosulfate pentahydrate, sodium aluminum silicate nonahydrate, sodium silicate pentahydrate, lithium chloride trihydrate, cobalt chloride hexahydrate, copper sulfate heptahydrate, ferrous sulfate heptahydrate, aluminum nitrate nonahydrate and calcium sulfate dihydrate.

3. The self-forming packaging material according to claim 1, characterized in that: The acrylic monomer includes one or more of acrylic acid, sodium acrylate, acrylamide, acrylate, stearic methacrylate, isopropyl acrylamide and hydroxyethyl methacrylate.

4. The self-forming packaging material according to claim 1, characterized in that: The polysaccharide monomers include one or more of alginic acid, sodium alginate, chitosan, starch and pectin.

5. The self-forming packaging material according to claim 1, characterized in that: The cross-linking agent includes N,N-methylenebisacrylamide.

6. The self-forming packaging material according to claim 1, characterized in that: The initiating material includes one or more of ammonium persulfate, potassium persulfate, hydrogen peroxide, dibenzoyl peroxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate and azobisisobutyronitrile.

7. A method for preparing the self-forming packaging material according to any one of claims 1 to 6, comprising the following steps: S1: mixing and melting the inorganic hydrated salt and the first portion of water to obtain solution A; S2: dissolving the acrylic acid monomer in the second portion of water and mixing with a cross-linking agent, a polysaccharide monomer, and a moisturizing material for ion cross-linking to obtain a solution B; the moisturizing material comprises lithium chloride and / or calcium chloride; S3: mixing the solution B and the solution A to obtain a solution C; S4: dissolving the initiating material in the remaining water and mixing with solution C to obtain the self-forming encapsulating material; There is no time sequence restriction for steps S1 and S2.

8. The preparation method according to claim 7, characterized in that: The melting temperature is 10-20° C. higher than the melting temperature of the inorganic hydrated salt.

9. The preparation method according to claim 7, characterized in that: The mixing of the solution B and the solution A is performed by adding the solution B into the solution A; during the adding process, the temperature of the system is 5 to 15° C. higher than the melting temperature of the inorganic hydrated salt.

10. Use of the self-forming packaging material according to any one of claims 1 to 6 or the self-forming packaging material prepared by the preparation method according to any one of claims 7 to 9 in battery potting.

11. A method for encapsulating a battery using the self-forming encapsulating material according to any one of claims 1 to 6 or the self-forming encapsulating material prepared by the preparation method according to any one of claims 7 to 9, comprising the following steps: The batteries to be packaged are arranged in a battery box, and the battery box is filled with self-forming packaging material, sealed, and cured to obtain a packaged battery pack.

12. The method according to claim 11, characterized in that The distance between adjacent batteries in the battery box is greater than 0.5 mm.

13. The method according to claim 11, characterized in that The flow rate of the self-forming packaging material during the filling process is 0.1 to 2.4 L / min.

14. The method according to claim 11, characterized in that The curing temperature is 20-80° C. and the curing time is 1-40 minutes.

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