Power battery, preparation method thereof and power utilization device

Abstract

The invention discloses a power battery, a preparation method thereof and a power utilization device, and relates to the technical field of batteries. The power battery comprises a battery cell module and a packaging assembly arranged on the periphery of the battery cell module in a surrounding mode, the packaging assembly comprises a packaging shell with a containing cavity and a packaging inner core arranged in the containing cavity, and the packaging shell is made of organic pouring sealant; and the material of the packaging inner core comprises a phase change material. The packaging shell formed by the pouring sealant material has fixing and insulating effects on the battery core, and meanwhile, the packaging shell with the accommodating cavity enables the pouring sealant to have a good packaging and protecting effect on the phase change material, so that the phase change material is prevented from being in direct contact with the battery, and the long-term insulativity and stability of the battery are not influenced. When the battery emits heat, heat can be transferred to the phase-change material of the internal packaging inner core through the packaging shell formed by the pouring sealant, so that the phase-change material stores heat in a phase-change manner, the temperature of the battery is further quickly reduced, the temperature between battery cores is balanced, and thermal runaway is reduced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a power battery, a preparation method thereof, and an electrical device. Background Art

[0002] With the rapid development of new energy vehicles, people are placing higher demands on battery power and range. High-energy-density battery packs have gradually become a hot topic in power battery research. Cylindrical batteries, due to their standardized production advantages (>98%), high energy density potential, and mechanical strength, have become a key approach for cost reduction (unit cost reduction of 34%) and breakthroughs in range in power vehicles. However, their uneven radial heat distribution (temperature differences between the center and surface of the cell can reach 15°C) leads to a high risk of thermal runaway. Once this occurs (trigger temperature >130°C), a chain reaction can occur within 30 seconds, threatening passenger safety.

[0003] In existing cylindrical battery packs, potting compound is a key functional material that connects the battery cells to the battery system. Filling the gaps between the cells, the potting compound stabilizes the cells, prevents displacement and friction, and protects against electrolyte corrosion and external moisture intrusion. However, in scenarios where the cells may experience thermal runaway (temperatures suddenly rising to 800°C), the potting compound exhibits significantly insufficient flame retardancy and thermal barrier properties. Summary of the Invention

[0004] The present application provides a power battery, a preparation method thereof, and an electrical device thereof, in order to improve the defects of existing potting glue in having obviously insufficient flame retardancy and heat barrier capability.

[0005] In a first aspect, the present application provides a power battery, comprising a cell module and a packaging assembly disposed around the cell module, wherein the packaging assembly comprises a packaging shell having a receiving cavity and a packaging core disposed in the receiving cavity, wherein: The material of the packaging shell includes organic potting glue; The material of the package core includes phase change material.

[0006] This application uses organic potting compound to form a cavity around the battery module and fills the cavity with phase change material. This allows the encapsulation shell formed by the potting compound to fix and insulate the battery. At the same time, the encapsulation shell with an accommodating cavity allows the potting compound to provide good encapsulation and protection for the phase change material, preventing direct contact between the phase change material and the battery, which would affect the battery's long-term insulation and stability. When the battery heats up, the heat can be transferred to the internal encapsulated core phase change material through the encapsulation shell formed by the potting compound, causing the phase change material to store heat through phase change, thereby quickly reducing the battery temperature, balancing the temperature between the battery cells, and reducing thermal runaway.

[0007] The thermal conductivity of potting compound is usually between 0.8 and 3 W / mk, which can conduct the heat of the battery to the phase change material, thereby reducing the temperature of the battery. The volume resistivity of potting compound is usually 5x10 12 Ω·cm~1x10 14 Ω·cm, which can provide better insulation performance. Choosing organic potting compound instead of inorganic potting compound can effectively protect the battery, enabling it to withstand various mechanical impacts and have long-term stability and reliability.

[0008] Phase change materials can typically be organic phase change materials such as paraffin waxes, fatty acids, and polyethylene glycols. They can also be inorganic phase change materials such as disodium hydrogen phosphate dodecahydrate, sodium sulfate decahydrate, calcium chloride hexahydrate, molten salts, and the like. Hydrogel materials can also be used. They provide phase change heat storage, promptly removing heat from the battery. At least one of a defoaming agent, a thermal conductor, a flame retardant, a hygroscopic agent, and a refrigerant can also be added to the package core. The defoaming agent can be selected from at least one of silicone, polyethers, mineral oil, and synthetic latex. The thermal conductor can be selected from at least one of aluminum oxide, zinc oxide, boron nitride, and graphene. The flame retardant can be selected from at least one of phosphate esters, aluminum hydroxide, magnesium hydroxide, and melamine cyanurate. The hygroscopic agent can be selected from at least one of calcium chloride, lithium chloride, and silica gel. The refrigerant can be selected from at least one of ethanol, ethylene glycol, and glycerol.

[0009] In some embodiments, the packaging shell includes a packaging inner layer that contacts the battery cell module and a packaging outer layer that does not contact the battery cell module, wherein the impact strength of the packaging outer layer of the battery cell module is less than the impact strength of the packaging inner layer. When the battery cell module is a cylindrical battery, the packaging shell is disposed on the side of the cylinder, and no packaging components are required on the top and bottom surfaces. When the battery cell module is square, the packaging shell is disposed on the four sides of the square, and no packaging components are required on the top and bottom surfaces. Since the packaging shell itself also encloses a cavity to accommodate the packaging inner core, the packaging component itself has a packaging inner layer that directly contacts the battery cell module, and a packaging outer layer that does not directly contact the battery cell module. Setting the impact strength of the packaging outer layer of the battery cell module to be less than the impact strength of the packaging inner layer can make the packaging inner layer more firmly bound and fixed to the battery cell module. When hydrogel is selected as the phase change material, when the battery cell experiences thermal runaway, the hydrogel material vaporizes to effectively dissipate heat and reduce temperature. The thermal conductivity of the vaporization layer produced during the vaporization process is <0.04W / mk, which has a good heat insulation effect and prevents the spread of thermal runaway. When the hydrogel vaporizes in large quantities, the large amount of vaporized water vapor can break through the organic potting glue layer on the outer layer of the package, further taking away heat to play a cooling role and reduce the probability of battery explosion.

[0010] In some embodiments, the impact strength of the outer layer of the package is 2 kJ / m 2 ~4kJ / m 2The impact strength of the outer packaging layer is within this range, so that when thermal runaway occurs in the battery cell, a large amount of vaporized water vapor can break through the organic potting layer of the outer packaging layer, further removing heat and having a cooling effect, reducing the probability of battery combustion and explosion. During normal operation, it can also provide packaging for the phase change material. The tensile strength of the outer packaging layer can be 0.1-0.5MPa, which can protect the internal packaging material while ensuring that the phase change component can break through the protective layer in the event of thermal runaway; and / or The impact strength of the inner layer of the package is 6kJ / m 2 ~10kJ / m 2 The impact strength of the inner packaging layer is within this range, providing fixation and insulation for the battery cell. Furthermore, when thermal runaway occurs, the large amount of vaporized water vapor will not break through the inner potting compound, reducing further damage to the battery. The tensile strength of the inner packaging layer can be greater than 1 MPa, enabling it to effectively protect the battery.

[0011] In some embodiments, the material of the outer packaging layer includes at least one of polyurethane, epoxy resin and liquid silicone. The material of the outer packaging layer is selected from at least one of the above materials, which can provide 2kJ / m 2 ~4kJ / m 2 The impact strength can provide fixation and insulation for the battery cell. At the same time, when the battery cell experiences thermal runaway, a large amount of vaporized water vapor will not break through the inner layer of potting glue, reducing further stimulation to the battery; and / or, The material of the inner layer of the package includes at least one of polyurethane, epoxy resin and liquid silicone. The material of the inner layer of the package is selected from at least one of the above materials, which can provide 6kJ / m 2 ~10kJ / m 2 The impact strength is so strong that when the battery cell experiences thermal runaway, a large amount of vaporized water vapor can break through the organic potting layer on the outer layer of the package, further taking away the heat to cool it down and reduce the probability of battery explosion. When working normally, it can also provide packaging for the phase change material.

[0012] Because the impact strength of the outer package layer is lower than that of the inner package layer, the crosslinking degree of the outer package layer material is lower than that of the inner package layer. For the outer package layer material, the crosslinking degree of polyurethane can be 5% to 12%, the crosslinking degree of epoxy resin can be 3% to 10%, and the crosslinking degree of liquid silicone can be 4% to 12%. For the inner package layer 212 material, the crosslinking degree of polyurethane can be 13% to 30%, the crosslinking degree of epoxy resin can be 12% to 26%, and the crosslinking degree of liquid silicone can be 13% to 28%.

[0013] In some embodiments, the thickness of the outer layer of the package is 0.1-3 mm. Within this range, the thickness of the outer layer of the package can protect the internal phase change material under normal conditions and ensure that the phase change component breaks through the protective layer to achieve a heat dissipation effect in the event of thermal runaway; and / or, The thickness of the inner packaging layer is 0.2-1 mm. Within this range, the inner packaging layer can effectively fix the battery core and protect the battery core from the influence of the phase change material.

[0014] In some embodiments, the phase change material comprises a hydrogel, wherein: The mass proportion of water in the hydrogel is 20% to 90%; and / or, The thermal conductivity of the hydrogel is 0.3W / mk to 1.2W / mk; and / or, The interfacial strength between the hydrogel and the potting compound is greater than or equal to 5 N / m; and / or, The compressive strength of the hydrogel is greater than or equal to 2.4 MPa; and / or, The hydrogel includes at least one of polyacrylamide, polyacrylic acid, poly(acrylic acid-co-acrylamide), sodium alginate, chitosan, dole gum and polyvinyl alcohol.

[0015] The hydrogel material has certain mechanical strength and toughness, and can effectively withstand external forces such as vibration and impact faced by the buffer battery. Under normal use conditions, hydrogel can effectively cool and balance the temperature between battery cells as a heat storage material (the surface temperature difference between battery cells is <1°C); when the battery is overcharged or overheated, causing thermal runaway, the hydrogel material vaporizes to effectively dissipate heat and cool down. The thermal conductivity coefficient of the vaporization layer generated during the vaporization process is <0.04W / mk, which exhibits good thermal insulation and prevents the spread of thermal runaway; finally, a large amount of vaporized water vapor can break through the outer organic potting layer, further taking away heat and playing a cooling role.

[0016] The mass proportion of water in the hydrogel is within this range, which can effectively vaporize and dissipate heat when the battery is in thermal runaway. The thermal conductivity of the hydrogel is within this range, which can have a good thermal conductivity and temperature uniformity during normal use of the battery. The interface strength between the hydrogel and the potting glue is within this range, which can improve the compatibility between the package core and the potting glue, and ensure the stability of each structural component when the battery module is subjected to external collision impact, avoiding the problem of peeling and delamination. The compressive strength of the hydrogel is within this range, which can match the mechanical properties of different materials in the component. Selecting at least one of the above hydrogels can enable rapid construction, safe and convenient operation.

[0017] In some embodiments, the height of the battery module is H1, and the thickness of the package core is D1, where: 0.8≤D1 / H1≤0.9. Within this range, the ratio of the package core thickness to the battery module height can provide sufficient phase change material for cooling and heat dissipation while ensuring mechanical structural stability, thereby reducing the risk of thermal runaway.

[0018] In a second aspect, the present application provides a method for preparing a power battery, for preparing the power battery of the first aspect, comprising the following steps: Preparing a potting material layer on the surface of the battery cell module; preparing a phase change material layer on the surface of the potting glue material layer; A potting material layer is prepared on the remaining surface of the phase change material layer to obtain a power battery.

[0019] An organic potting glue material is scraped or sprayed on the battery array and pre-cured at room temperature for 0.5 hours to form a potting glue material layer; a hydrogel slurry is scraped or sprayed on the surface of the potting glue material layer and cured at room temperature for 5 to 10 minutes to prepare a phase change material layer; finally, an organic potting glue material is scraped or sprayed on the surface of the prepared phase change material layer and pre-cured at room temperature for 30 minutes to prepare a potting glue material layer, and the gel surface is encapsulated to obtain a power battery.

[0020] In some embodiments, the impact strength of the potting material layer prepared on the surface of the battery cell module is greater than the impact strength of the potting material layer prepared on the remaining surface of the phase change material layer. This can make the inner layer of the package more firmly bound and fixed to the battery cell module. When the phase change material is hydrogel, when the battery cell experiences thermal runaway, the hydrogel material vaporizes and can effectively dissipate heat and cool down. The thermal conductivity of the vaporized layer generated during the vaporization process is less than 0.04W / mk, which has a good heat-insulating effect and prevents the spread of thermal runaway. When the hydrogel vaporizes in large quantities, the large amount of vaporized water vapor can break through the organic potting layer of the outer layer of the package, further taking away heat to cool down the battery and reduce the probability of battery explosion.

[0021] In a third aspect, the present application provides an electrical device comprising the power battery of the first aspect. The electrical device includes, but is not limited to, new energy vehicles, energy storage, drones, flying cars, robots, and power tools. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1This is a schematic structural diagram of a power battery according to an embodiment of the present application.

[0024] Figure 2 This is a cross-sectional view of a power battery according to an embodiment of the present application.

[0025] Figure 3 This is a cross-sectional view of a packaging assembly of a power battery according to an embodiment of the present application.

[0026] Figure 4 This is a cross-sectional view of the packaging inner layer, packaging outer layer, and accommodating cavity of a power battery according to an embodiment of the present application.

[0027] Description of Figure Numbers: 100 power battery; 1 battery cell module; 2 packaging assembly; 21 packaging shell; 211 accommodating cavity; 212 packaging inner layer; 213 packaging outer layer; 22 packaging inner core. DETAILED DESCRIPTION

[0028] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of this application.

[0029] With the rapid development of new energy vehicles, people are placing higher demands on battery power and range. High-energy-density battery packs have gradually become a hot topic in power battery research. Cylindrical batteries, due to their standardized production advantages (>98%), high energy density potential, and mechanical strength, have become a key approach for cost reduction (unit cost reduction of 34%) and breakthroughs in range in power vehicles. However, their uneven radial heat distribution (temperature differences between the center and surface of the cell can reach 15°C) leads to a high risk of thermal runaway. Once this occurs (trigger temperature >130°C), a chain reaction can occur within 30 seconds, threatening passenger safety.

[0030] In existing cylindrical battery packs, potting compound is a key functional material that connects the battery cells to the battery system. The potting compound, filling the gaps between the cells, stabilizes the cells, prevents displacement and friction, and protects against electrolyte corrosion and external moisture intrusion. Furthermore, the thermally conductive potting compound quickly conducts heat from the cells to the liquid cooling plate or heat dissipation structure, equalizing the temperature between the cells. Furthermore, its flame retardant properties effectively slow the spread of flames and suppress the release of harmful gases. When high-energy-density cylindrical batteries experience thermal runaway, a single potting compound presents several significant drawbacks. When the temperature difference between the top and bottom of the cylindrical cell exceeds 10°C, the potting compound's lateral thermal conductivity drops by over 30%, resulting in uneven radial heat distribution. The polymer-based potting compound exhibits a significant difference in thermal expansion coefficient from the aluminum shell and copper tabs of the battery cell. This makes the interface susceptible to debonding during long-term temperature cycling, creating a thermally resistant interface. Electrolyte penetration or moisture intrusion accelerates potting compound aging, further reducing the material's thermal conductivity. More importantly, in the event of thermal runaway (where temperatures suddenly rise to 800°C), the potting compound's flame retardancy and thermal barrier properties are significantly insufficient. Ordinary UL94V-0 grade compounds decompose above 500°C and release flammable gases, exacerbating the chain reaction. While the aerogel layer can slow heat conduction, it cannot prevent the potting compound's structural collapse (its elastic modulus decreases by 90% above 600°C), leading to failure of the liquid cooling line. When faced with thermal runaway, the failed potting compound accumulates heat, preventing it from effectively and promptly dissipating it, potentially triggering a chain reaction in adjacent cells. Furthermore, the active cooling system's response speed in the early stages of thermal runaway (typically ≥10 seconds) struggles to keep up with the sudden heat generation rate (peak heat generation rate of 50W / s).

[0031] A phase-change microcapsule for lithium battery potting adhesive and its preparation method utilizes oil-in-water and self-assembly techniques to prepare a type of aluminum hydroxide-coated paraffin phase-change microcapsule. Compared to existing organic-shell phase-change microcapsules, these microcapsules exhibit higher thermal conductivity. Furthermore, because aluminum hydroxide is an excellent inorganic flame retardant, they address the issues of low thermal conductivity when added alone, easy leakage during solid-liquid phase transitions, and flammability. These microcapsules, added as a phase-change filler to lithium-ion battery potting adhesives, enhance the safety of these batteries. However, the overall mass of the phase-change material is low, the overall thermal conductivity is not high, and there is still a risk of leakage at high temperatures.

[0032] In view of this, the present application provides a power battery, a preparation method thereof, and an electrical device to improve the problem that the existing potting compound has obviously insufficient flame retardancy and heat barrier capability.

[0033] First, as Figures 1 to 4 As shown, the present application provides a power battery 100, including a cell module 1 and a packaging assembly 2 arranged around the cell module 1, wherein the packaging assembly 2 includes a packaging shell 21 having an accommodating cavity 211 and a packaging core 22 arranged in the accommodating cavity 211, wherein: The material of the package shell 21 includes organic potting glue; The material of the package core 22 includes phase change material.

[0034] This application uses an organic potting compound to form a cavity 211 around the battery module 1 and fills the cavity with a phase change material. This allows the encapsulation shell 21 formed by the potting compound to fix and insulate the battery cell. At the same time, the encapsulation shell 21 with the cavity 211 allows the potting compound to provide good encapsulation and protection for the phase change material, preventing direct contact between the phase change material and the battery, which would affect the battery's long-term insulation and stability. When the battery heats up, the heat can be transferred through the encapsulation shell 21 formed by the potting compound to the phase change material in the internal encapsulation core 22, causing the phase change material to store heat through phase change, thereby rapidly reducing the battery temperature, balancing the temperature between the battery cells, and reducing thermal runaway.

[0035] The thermal conductivity of potting compound is usually between 0.8 and 3 W / mk, which can conduct the heat of the battery to the phase change material, thereby reducing the temperature of the battery. The volume resistivity of potting compound is usually 5x10 12 Ω·cm~1x10 14 Ω·cm, which can provide better insulation performance. Choosing organic potting compound instead of inorganic potting compound can effectively protect the battery from various mechanical impacts and ensure long-term stability and reliability.

[0036] Phase change materials can generally be organic phase change materials such as paraffin, fatty acids, polyethylene glycol, etc. They can also be inorganic phase change materials such as disodium hydrogen phosphate dodecahydrate, sodium sulfate decahydrate, calcium chloride hexahydrate, molten salt, etc. They can also be hydrogel materials. They provide phase change heat storage and promptly remove the heat of the battery. At least one of a defoaming agent, a thermal conductor, a flame retardant, a hygroscopic agent, and a refrigerant can also be added to the package core 22. The defoaming agent can be selected from at least one of silicone, polyether, mineral oil, and synthetic latex. The thermal conductor can be selected from at least one of aluminum oxide, zinc oxide, boron nitride, and graphene. The flame retardant can be selected from at least one of phosphate esters, aluminum hydroxide, magnesium hydroxide, and melamine cyanurate. The hygroscopic agent can be selected from at least one of calcium chloride, lithium chloride, and silica gel. The refrigerant can be selected from at least one of ethanol, ethylene glycol, and glycerol.

[0037] The battery cell module 1 can be a high-nickel ternary system, a high-nickel high-silicon combination system, lithium iron phosphate, lithium cobalt oxide / lithium manganese oxide and other cylindrical batteries. The outer shell of the cylindrical battery is an insulating PP or PET film; the battery cell arrangement can be one or more combinations of horizontal array arrangement, horizontal lying stacking or diagonal stacking.

[0038] In combination with the first aspect, in some embodiments provided herein, the packaging shell 21 includes a packaging inner layer 212 that contacts the battery cell module 1 and a packaging outer layer 213 that does not contact the battery cell module 1, wherein the impact strength of the packaging outer layer 213 of the battery cell module 1 is less than the impact strength of the packaging inner layer 212. When the battery cell module 1 is a cylindrical battery, the packaging shell 21 is provided on the side of the cylinder, and the packaging component 2 does not need to be provided on the top and bottom surfaces. When the battery cell module 1 is square, the packaging shell 21 is provided on the four sides of the square, and the packaging component 2 does not need to be provided on the top and bottom surfaces. Because the packaging shell 21 itself also encloses a cavity to accommodate the packaging inner core 22, the packaging assembly 2 itself has a packaging inner layer 212 that directly contacts the battery cell module 1, and a packaging outer layer 213 that does not directly contact the battery cell module 1. The impact strength of the packaging outer layer 213 of the battery cell module 1 is set to be lower than the impact strength of the packaging inner layer 212, so that the packaging inner layer 212 can more firmly bind and fix the battery cell module 1. When the phase change material is a hydrogel, when the battery cell experiences thermal runaway, the hydrogel material vaporizes to effectively dissipate heat and reduce the temperature. The thermal conductivity of the vaporized layer produced during the vaporization process is less than 0.04W / mk, which has an excellent thermal insulation effect and prevents the spread of thermal runaway. When the hydrogel vaporizes in large quantities, the large amount of vaporized water vapor can break through the organic potting layer of the packaging outer layer 213, further removing heat and having a cooling effect, reducing the probability of battery explosion.

[0039] In combination with the first aspect, in some embodiments provided in this application, the impact strength of the outer packaging layer 213 is 2 kJ / m 2 ~4kJ / m 2 The impact strength of the outer packaging layer 213 within this range allows for a large amount of vaporized water vapor to break through the organic potting compound layer of the outer packaging layer 213 when thermal runaway occurs, further removing heat and cooling the battery, reducing the probability of explosion. During normal operation, the outer packaging layer 213 also provides encapsulation for the phase change material. The tensile strength of the outer packaging layer 213 can be between 0.1 and 0.5 MPa, allowing it to both protect the internal packaging material and ensure that the phase change component can break through the protective layer during thermal runaway.

[0040] In combination with the first aspect, in some embodiments provided in this application, the impact strength of the packaging inner layer 212 is 6 kJ / m 2 ~10kJ / m 2 The impact strength of the inner packaging layer 212 is within this range, providing fixation and insulation for the battery cell. Furthermore, when thermal runaway occurs, the large amount of vaporized water vapor will not break through the inner potting compound, reducing further damage to the battery. The tensile strength of the inner packaging layer 212 can be greater than 1 MPa, effectively protecting the battery.

[0041] In combination with the first aspect, in some embodiments provided in the present application, the material of the outer packaging layer 213 includes at least one of polyurethane, epoxy resin and liquid silicone. The material of the outer packaging layer 213 is selected from at least one of the above materials, which can provide 2kJ / m 2 ~4kJ / m 2 The impact resistance can provide fixation and insulation for the battery cell. At the same time, when the battery cell experiences thermal runaway, a large amount of vaporized water vapor will not break through the inner layer of potting glue, reducing further stimulation to the battery.

[0042] In combination with the first aspect, in some embodiments provided in this application, the material of the encapsulation inner layer 212 includes at least one of polyurethane, epoxy resin and liquid silicone. The material of the encapsulation inner layer 212 is selected from at least one of the above materials, which can provide 6kJ / m 2 ~10kJ / m 2 The impact resistance is such that when the battery cell experiences thermal runaway, a large amount of vaporized water vapor can break through the organic potting glue layer of the outer package layer 213, further taking away the heat to play a cooling role, reducing the probability of battery explosion, and during normal operation, it can provide packaging for the phase change material.

[0043] Because the impact strength of outer packaging layer 213 is lower than that of inner packaging layer 212, the crosslinking degree of the material of outer packaging layer 213 is lower than that of inner packaging layer 212. Among the materials of outer packaging layer 213, the crosslinking degree of polyurethane can be 5% to 12%, the crosslinking degree of epoxy resin can be 3% to 10%, and the crosslinking degree of liquid silicone can be 4% to 12%. Among the materials of inner packaging layer 212, the crosslinking degree of polyurethane can be 13% to 30%, the crosslinking degree of epoxy resin can be 12% to 26%, and the crosslinking degree of liquid silicone can be 13% to 28%.

[0044] In combination with the first aspect, in some embodiments provided in the present application, the thickness of the outer packaging layer 213 is 0.1~3mm. The thickness of the outer packaging layer 213 is within this range, which can protect the internal phase change material under normal circumstances and ensure that the phase change component breaks through the protective layer to achieve heat dissipation effect in the event of thermal runaway.

[0045] In conjunction with the first aspect, in some embodiments provided herein, the thickness of the packaging inner layer 212 is 0.2-1 mm. Within this range, the packaging inner layer 212 can effectively secure the battery cell and protect it from the effects of the phase change material.

[0046] In conjunction with the first aspect, in some embodiments provided herein, the phase change material comprises a hydrogel, wherein: the mass fraction of water in the hydrogel ranges from 20% to 90%. The hydrogel material possesses a certain degree of mechanical strength and toughness, effectively withstanding external forces such as vibration and impact faced by the buffer battery. Under normal operating conditions, the hydrogel, as a heat storage material, can effectively cool and balance the temperature between battery cells (the surface temperature difference between cells is <1°C). When the battery is overcharged or overheated, causing thermal runaway, the hydrogel material vaporizes, effectively dissipating heat and cooling the battery. The vaporized layer produced during the vaporization process has a thermal conductivity of <0.04W / mk, exhibiting excellent insulation and preventing the spread of thermal runaway. Finally, the large amount of vaporized water vapor can break through the outer organic potting layer, further removing heat and providing a cooling effect. The mass fraction of water in the hydrogel within this range allows for effective vaporization and heat dissipation during thermal runaway.

[0047] In conjunction with the first aspect, in some embodiments provided herein, the phase change material includes a hydrogel, wherein the hydrogel has a thermal conductivity of 0.3 W / mk to 1.2 W / mk. Within this range, the hydrogel can provide good thermal conductivity and temperature uniformity during normal battery use.

[0048] In conjunction with the first aspect, in some embodiments provided herein, the phase change material includes a hydrogel, wherein the interfacial strength between the hydrogel and the potting compound is greater than or equal to 5 N / m. This interfacial strength between the hydrogel and the potting compound is within this range, thereby improving the compatibility between the package core 22 and the potting compound, ensuring the stability of various structural components when the battery module is subjected to external impact, and preventing delamination.

[0049] In conjunction with the first aspect, in some embodiments provided herein, the phase change material comprises a hydrogel, wherein: the compressive strength of the hydrogel is greater than or equal to 2.4 MPa. The compressive strength of the hydrogel is within this range, which can meet the matching of mechanical properties of different materials in the component.

[0050] In conjunction with the first aspect, in some embodiments provided herein, the phase change material comprises a hydrogel, wherein the hydrogel comprises at least one of polyacrylamide, polyacrylic acid, poly(acrylic acid-co-acrylamide), sodium alginate, chitosan, dole gum, and polyvinyl alcohol. Selecting at least one of these hydrogels allows for rapid construction and safe and convenient operation.

[0051] In conjunction with the first aspect, in some embodiments provided herein, the height of the battery cell module 1 is H1, and the thickness of the package core 22 is D1, where: 0.8≤D1 / H1≤0.9. Within this range, the ratio of the package core 22 thickness to the battery cell module 1 height can provide sufficient phase change material for cooling and heat dissipation while ensuring mechanical structural stability, thereby reducing the risk of thermal runaway.

[0052] In a second aspect, the present application provides a method for preparing a power battery 100 , for preparing the power battery 100 of the first aspect, comprising the following steps: Preparing a potting material layer on the surface of the battery cell module 1; preparing a phase change material layer on the surface of the potting glue material layer; A potting material layer is prepared on the remaining surface of the phase change material layer to obtain the power battery 100 .

[0053] An organic potting material is scraped or sprayed on the battery array and pre-cured at room temperature for 0.5 hours to form a potting material layer. A hydrogel slurry is scraped or sprayed on the surface of the potting material layer and cured at room temperature for 5 to 10 minutes to prepare a phase change material layer. Finally, an organic potting material is scraped or sprayed on the surface of the prepared phase change material layer and pre-cured at room temperature for 30 minutes to prepare a potting material layer. The gel surface is encapsulated to obtain a power battery 100.

[0054] In combination with the second aspect, in some embodiments provided in the present application, the impact strength of the potting material layer prepared on the surface of the battery cell module 1 is greater than the impact strength of the potting material layer prepared on the remaining surface of the phase change material layer. This can make the inner layer 212 of the package more firmly bound and fixed to the battery cell module 1. When the phase change material is hydrogel, when thermal runaway occurs in the battery cell, the vaporization of the hydrogel material can effectively dissipate heat and cool down. The thermal conductivity of the vaporization layer generated during the vaporization process is less than 0.04W / mk, which has a good heat insulation effect and prevents the spread of thermal runaway. When the hydrogel vaporizes in large quantities, a large amount of vaporized water vapor can break through the organic potting glue layer of the outer layer 213 of the package, further taking away heat to play a cooling role and reduce the probability of battery explosion.

[0055] In a third aspect, this application provides an electrical device comprising the power battery 100 of the first aspect. Such electrical devices include, but are not limited to, new energy vehicles, energy storage systems, drones, flying cars, robots, and power tools. Such electrical devices incorporate all the technical solutions of the power battery 100 and, therefore, possess all the beneficial effects of the power battery 100. This application will not further elaborate on these details.

[0056] The technical solution provided by this application is described in detail below with reference to the embodiments. A cylindrical battery is used as an example for illustration, and the battery cell modules are all of the same size.

[0057] Example 1 Embodiment 1 of the present application provides a power battery, including a cell module and a packaging assembly disposed around the cell module, wherein the packaging assembly includes a packaging shell having an accommodating cavity and a packaging inner core disposed in the accommodating cavity, and the packaging shell includes a packaging inner layer that contacts the cell module and a packaging outer layer that does not contact the cell module: The material of the outer packaging layer includes polyurethane with a cross-linking strength of 6%, a thickness of 0.1 mm, and an impact strength of 2 kJ / m 2 ; The material of the inner layer of the package includes epoxy resin with a cross-linking strength of 18%, a thickness of 0.2 mm, and an impact strength of 6 kJ / m 2 ; The material of the encapsulated inner core includes polyacrylamide hydrogel, has a thickness of 50 mm, and water accounts for 20% of the mass.

[0058] Example 2 Embodiment 2 of the present application provides a power battery, including a cell module and a packaging assembly disposed around the cell module, wherein the packaging assembly includes a packaging shell having an accommodating cavity and a packaging inner core disposed in the accommodating cavity, and the packaging shell includes a packaging inner layer that contacts the cell module and a packaging outer layer that does not contact the cell module: The material of the outer layer of the package includes epoxy resin with a cross-linking strength of 5%, a thickness of 1.5 mm, and an impact strength of 4 kJ / m 2 ; The material of the inner packaging layer includes silicone with a cross-linking strength of 20%, a thickness of 1 mm, and an impact strength of 10 kJ / m 2 ; The material of the package core includes dole gum, has a thickness of 60 mm, and the mass proportion of water is 90%.

[0059] Example 3 Embodiment 3 of the present application provides a power battery, including a cell module and a packaging assembly disposed around the cell module, wherein the packaging assembly includes a packaging shell having an accommodating cavity and a packaging inner core disposed in the accommodating cavity, and the packaging shell includes a packaging inner layer that contacts the cell module and a packaging outer layer that does not contact the cell module: The material of the outer packaging layer includes silicone with a cross-linking strength of 8%, a thickness of 3mm, and an impact strength of 3kJ / m 2 ; The material of the inner layer of the package includes polyurethane with a cross-linking strength of 24%, a thickness of 0.6 mm, and an impact strength of 8 kJ / m 2 ; The material of the package inner core includes polyvinyl alcohol hydrogel, has a thickness of 55 mm, and the mass proportion of water is 50%.

[0060] Comparative Example 1 Comparative Example 1 of the present application provides a power battery, which is similar to Example 1, except that only the solid packaging shell is formed by the inner layer of potting glue.

[0061] Comparative Example 2 Comparative Example 2 of the present application provides a power battery, which is similar to Example 1, except that it only has a packaging inner layer and a packaging inner core, but no packaging outer layer.

[0062] Comparative Example 3 Comparative Example 3 of the present application provides a power battery, which is similar to Example 1, except that it only has a packaging outer layer and a packaging inner core, but no packaging inner layer.

[0063] Comparative Example 4 Comparative Example 4 of the present application provides a power battery, which is similar to Example 1, except that it does not have a packaging component.

[0064] Comparative Example 5 Comparative Example 5 of the present application provides a power battery, which is similar to Example 1, except that half of the surface in contact with the battery cell is encapsulated by the encapsulation inner core material, and half of the surface in contact with the battery cell is encapsulated by the encapsulation inner layer material.

[0065] Performance Testing The power batteries of Examples 1 to 3 and the power batteries of Comparative Examples 1 to 5 were subjected to performance tests to test their thermal runaway performance. The specific test method is as follows: A standard 21700 battery cell (6000mAh, 3.6V, built-in 8mΩ) was selected as the research object for experimental testing of battery thermal runaway caused by overheating. The specific procedure was as follows: Two fully charged cylindrical batteries were placed in the center of a 62mm*41mm*80mm epoxy resin tank. The negative terminals of the batteries were secured to the bottom of the tank with PU glue, with a spacing of 5mm between the batteries. A heating plate was attached to one of the batteries (cell 1). The sides of cell 1 and the adjacent cell (cell 2) were both fitted with temperature monitoring thermocouples. An inner layer of potting compound, a phase change material, and an outer layer of potting compound were sequentially injected into the battery tank. After fully curing for 1 hour, the heating plate was applied to induce thermal runaway in cell 1. Heating was stopped after thermal runaway occurred. The temperature changes of the runaway battery and the adjacent cells were monitored, and the experimental phenomena were observed. The specific test results are shown in Table 1.

[0066] Table 1 Performance of the power batteries of Examples 1 to 3 and Comparative Examples 1 to 5

[0067] As shown in Table 1, in Examples 1 to 3, the surface temperature of the batteries is significantly lower than that without potting glue (Comparative Example 4), the temperature of the adjacent No. 2 battery cell is lower than 280°C, the appearance of the battery cell is intact, and no thermal runaway chain reaction occurs.

[0068] In Comparative Example 1, the out-of-control battery cell cannot be cooled and dissipated, causing the temperature of the adjacent battery cells to be significantly higher, triggering the critical value of thermal runaway and causing a chain reaction.

[0069] In comparative example 2, during long-term use, the phase change components may be damaged or deteriorated due to external impacts, the influence of ambient temperature and humidity, and their heat dissipation and cooling effects may be reduced. When facing thermal runaway of the battery, there is a risk that the cooling and heat dissipation effects may be greatly reduced.

[0070] Although the adjacent No. 2 battery cell in Comparative Example 3 did not experience thermal runaway, the battery had the defect of chemical corrosion under high temperature and high pressure conditions or long-term storage and use, and there was a risk of leakage.

[0071] In comparative example 4, there is no use of potting glue. Both battery cells will quickly thermally run away, and the battery cells lack mechanical fixation, which may cause them to explode or burst out of the packaging slot during the runaway process.

[0072] Comparative Example 5 has a relatively low proportion of phase change material, which fails to prevent thermal runaway, and half of it is in direct contact with the battery cell, posing a risk of chemical corrosion during long-term storage or normal use.

[0073] In summary, by using an organic potting compound to form a cavity around the battery module and then filling the cavity with a phase-change material, the potting compound's encapsulation shell can secure and insulate the battery cell. Furthermore, the encapsulation shell with an accommodating cavity provides the potting compound with excellent encapsulation and protection for the phase-change material, preventing direct contact between the phase-change material and the battery, which could affect the battery's long-term insulation and stability. When the battery heats up, the heat can be transferred through the potting compound's encapsulation shell to the internal phase-change material, causing the phase-change material to undergo a phase change and store heat, thereby rapidly reducing the battery's temperature, equalizing the temperature between the cells, and reducing thermal runaway.

[0074] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments / methods or examples. In addition, those skilled in the art may combine and combine different embodiments / methods or examples described in this specification and the features of different embodiments / methods or examples, unless they are contradictory.

[0075] It should be noted that, in the present application, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment comprising a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or equipment comprising the elements. In the present application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly specified.

[0076] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A power battery, characterized in that: The invention comprises a battery cell module and a packaging component arranged around the battery cell module, wherein the packaging component comprises a packaging shell having an accommodating cavity and a packaging core arranged in the accommodating cavity, wherein: The material of the packaging shell includes organic potting glue; The material of the package core includes phase change material.

2. The power battery according to claim 1, characterized in that: The packaging shell includes a packaging inner layer that contacts the battery cell module and a packaging outer layer that does not contact the battery cell module, wherein the impact strength of the packaging outer layer of the battery cell module is lower than the impact strength of the packaging inner layer.

3. The power battery according to claim 2, wherein: The impact strength of the outer layer of the package is 2kJ / m 2 ~4kJ / m 2 and / or, The impact strength of the inner layer of the package is 6kJ / m 2 ~10kJ / m 2 .

4. The power battery according to claim 2, wherein: The material of the outer packaging layer includes at least one of polyurethane, epoxy resin and liquid silicone; and / or, The material of the inner packaging layer includes at least one of polyurethane, epoxy resin and liquid silicone.

5. The power battery according to claim 2, wherein: The thickness of the outer packaging layer is 0.1-3 mm; and / or, The thickness of the inner packaging layer is 0.2-1 mm.

6. The power battery according to claim 1, wherein: The phase change material comprises a hydrogel, wherein: The mass proportion of water in the hydrogel is 20% to 90%; and / or, The thermal conductivity of the hydrogel is 0.3W / mk to 1.2W / mk; and / or, The interfacial strength between the hydrogel and the potting compound is greater than or equal to 5 N / m; and / or, The compressive strength of the hydrogel is greater than or equal to 2.4 MPa; and / or, The hydrogel includes at least one of polyacrylamide, polyacrylic acid, poly(acrylic acid-co-acrylamide), sodium alginate, chitosan, dole gum and polyvinyl alcohol.

7. The power battery according to claim 1, wherein: The height of the battery cell module is H1, and the thickness of the package core is D1, wherein: 0.8≤D1 / H1≤0.

9.

8. A method for preparing a power battery according to any one of claims 1 to 7, characterized in that: The following steps are involved: Preparing a potting material layer on the surface of the battery cell module; preparing a phase change material layer on the surface of the potting glue material layer; A potting material layer is prepared on the remaining surface of the phase change material layer to obtain a power battery.

9. The method for preparing a power battery according to claim 8, wherein: The impact resistance of the potting material layer prepared on the surface of the battery core module is greater than the impact resistance of the potting material layer prepared on the remaining surface of the phase change material layer.

10. An electrical device, characterized in that: Comprising the power battery according to any one of claims 1 to 7.

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