Lithium ion battery with high and low temperature resistance and preparation method thereof

Abstract

The application discloses a lithium ion battery with high and low temperature resistance and a preparation method thereof. The lithium ion battery comprises a battery cell and a shell for packaging the battery cell. The outer surface of the shell is provided with a first groove and a second groove, and the first groove and the second groove are embedded side by side on the outer surface of the shell. The first groove and the second groove are respectively extended in a meandering manner from the center of the outer surface of the shell to the edge of the outer surface of the shell. The first groove is provided with a low-temperature-resistant material layer, and the phase transition temperature of the low-temperature-resistant material layer is -12 DEG C to -15 DEG C. The second groove is provided with a high-temperature-resistant material layer, and the phase transition temperature of the high-temperature-resistant material layer is 57 DEG C to 62 DEG C. The thickness of the low-temperature-resistant material layer is the same as the depth of the first groove, and the thickness of the high-temperature-resistant material layer is the same as the depth of the second groove. The outer surfaces of the low-temperature-resistant material layer, the high-temperature-resistant material layer and the shell are on the same horizontal plane. The lithium ion battery provided by the application can still maintain stable performance under extreme high and low temperature conditions.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a lithium-ion battery with high and low temperature resistance and its preparation method. Background Technology

[0002] Lithium-ion batteries, as a key component in modern energy applications, are widely used in consumer electronics, electric vehicles, and large-scale energy storage systems due to their high energy density, long cycle life, and environmental friendliness. However, with the diversification and extreme nature of application scenarios, the performance limitations of traditional lithium-ion batteries in high and low temperature environments are becoming increasingly apparent, becoming a bottleneck restricting their further development.

[0003] In low-temperature environments, lithium-ion batteries face severe performance degradation. As temperatures decrease, the viscosity of the electrolyte increases significantly, leading to a substantial reduction in the migration rate of lithium ions. This not only increases the internal impedance of the battery but also causes a sharp decline in charge and discharge efficiency. Specifically, this manifests as prolonged charging time and reduced discharge capacity, severely impacting the battery's practical performance in cold regions or low-temperature applications. For example, in environments below -15°C, the discharge capacity of conventional lithium-ion batteries may drop to less than 50% of that at room temperature.

[0004] On the other hand, high-temperature environments also pose significant challenges to the performance and safety of lithium-ion batteries. Increased temperature accelerates internal side reactions within the battery, such as electrolyte decomposition and structural changes in the positive and negative electrode materials. These reactions not only lead to rapid capacity decay and a significant reduction in cycle life but can also trigger more serious safety issues. For example, in environments above 60°C, batteries may experience thermal runaway, causing battery swelling, smoke, or even explosions.

[0005] In existing technologies, researchers have explored various methods to improve the temperature adaptability of lithium-ion batteries, such as developing novel electrolyte additives, improving electrode material structures, and optimizing battery management systems. However, these methods often only improve battery performance to a certain extent within a specific temperature range, making it difficult to simultaneously meet the requirements for use in high and low temperature environments. Furthermore, some improvements may increase battery manufacturing costs or reduce other performance indicators (such as energy density).

[0006] Therefore, developing a lithium-ion battery that can maintain stable performance over a wide temperature range, especially one that can still operate efficiently under extreme high and low temperature conditions, is of great significance for expanding the application areas of batteries, improving user experience, and ensuring safety. Summary of the Invention

[0007] The main objective of this invention is to address the shortcomings of existing lithium-ion batteries in meeting the requirements for use under high and low temperature conditions, and to provide a lithium-ion battery with high and low temperature resistance and its preparation method.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A lithium-ion battery with high and low temperature resistance includes: a battery cell and a casing for encapsulating the battery cell;

[0010] The outer surface of the housing is provided with a first groove and a second groove, and the first groove and the second groove are embedded side by side on the outer surface of the housing. The first groove and the second groove extend from the center of the outer surface of the housing to the edge of the outer surface of the housing in a U-shape.

[0011] The first groove is provided with a low-temperature resistant material layer, the phase transition temperature of which is -12℃ to -15℃; the second groove is provided with a high-temperature resistant material layer, the phase transition temperature of which is 57℃ to 62℃.

[0012] The thickness of the low-temperature resistant material layer is the same as the depth of the first groove, and the thickness of the high-temperature resistant material layer is the same as the depth of the second groove; and the outer surfaces of the low-temperature resistant material layer, the high-temperature resistant material layer, and the shell are on the same horizontal plane.

[0013] Preferably, the low-temperature resistant material layer comprises the following components in the indicated weight ratios: 40-50 parts of n-tetane, 25-35 parts of n-dodecane, 10-15 parts of 2-methylpentane, 3-5 parts of polyvinyl alcohol, 2-4 parts of graphene, 1-2 parts of nano-alumina, and 0.5-1 parts of silica aerogel.

[0014] Preferably, the high-temperature resistant material layer comprises the following components in the indicated weight ratios: 45-55 parts glyceryl stearate, 20-25 parts palmitic acid, 10-15 parts polyethylene glycol 4000, 3-5 parts carbon nanotubes, 2-3 parts boron nitride nanosheets, 1-2 parts expanded graphite, and 0.5-1 parts nano-magnesium oxide.

[0015] Preferably, the depth of the first groove is H1, the depth of the second groove is H2, the thickness of the low-temperature resistant material layer is h1, the thickness of the high-temperature resistant material layer is h2, and the wall thickness of the shell is H; wherein, H, H1, H2, h1, and h2 satisfy the following relationships: h1 = h2 = H1 = H2; 0.2H ≤ H1 ≤ 0.6H; 0.2H ≤ H2 ≤ 0.6H.

[0016] Preferably, the projected area of ​​the low-temperature resistant material layer is S1, the projected area of ​​the high-temperature resistant material layer is S2, and the projected area of ​​the shell is S; wherein, S1, S2 and S satisfy the relationship: 0.6S≤S1+S2≤S.

[0017] Preferably, the outer surface of the housing is further provided with a third groove, which is embedded side by side between the first groove and the second groove, and the third groove extends from the center of the outer surface of the housing to the edge of the outer surface of the housing in a U-shape.

[0018] The third groove is provided with a buffer thermally conductive material layer; the thickness of the buffer thermally conductive material layer is greater than the thickness of the low-temperature resistant material layer or the high-temperature resistant material layer, and the buffer thermally conductive material layer protrudes from the outer surface of the shell;

[0019] The buffer thermal conductive material layer includes a first aluminum foam, a second aluminum foam, and a third aluminum foam arranged sequentially from the outside to the inside. The densities ρ1 of the first aluminum foam, ρ2 of the second aluminum foam, and ρ3 of the third aluminum foam satisfy the relationship: ρ1 > ρ2 > ρ3. Furthermore, the first aluminum foam, the second aluminum foam, and the third aluminum foam are all provided with staggered pore structures. The porosities Q1 of the first aluminum foam, Q2 of the second aluminum foam, and Q3 of the third aluminum foam satisfy the relationship: Q1 < Q2 < Q3.

[0020] Preferably, the density ρ1 of the first aluminum foam is 0.8–1.2 g / cm³. 3 The density ρ2 of the second aluminum foam is 0.5–0.8 g / cm³. 3 The density ρ3 of the third aluminum foam is 0.2–0.5 g / cm³. 3 ;

[0021] The porosity Q1 of the first aluminum foam is 45% to 60%; the porosity Q2 of the second aluminum foam is 60% to 75%; and the porosity Q3 of the third aluminum foam is 75% to 90%.

[0022] Preferably, the outer surface of the housing is further provided with a third groove, which is embedded side by side between the first groove and the second groove, and the third groove extends from the center of the outer surface of the housing to the edge of the outer surface of the housing in a U-shape.

[0023] The third groove is provided with a heat insulation and buffer material layer, the thickness of which is greater than the thickness of the low temperature resistant material layer or the high temperature resistant material layer, and the heat insulation and buffer material layer protrudes from the outer surface of the shell.

[0024] The heat insulation and buffering material layer is ceramicized silicone foam, which comprises the following components in parts by weight: 30-40 parts vinyl silicone oil, 10-20 parts silica, 20-50 parts nano-ceramic powder, 0.1-1.0 parts ethynylcyclohexanol, 1-10 parts hydrogen-containing silicone oil, 1-10 parts hydroxyl silicone oil, 0.1-1.0 parts platinum catalyst, 10-20 parts β-nepheline, and 1-8 parts halloysite nanotubes.

[0025] Preferably, the outer surface of the housing is further provided with a third groove, which is embedded side by side between the first groove and the second groove, and the third groove extends from the center of the outer surface of the housing to the edge of the outer surface of the housing in a U-shape.

[0026] The third groove is provided with modified thermally conductive silicone, the porosity of which is 65% to 85%, the thickness of which is greater than the thickness of the low-temperature resistant material layer or the high-temperature resistant material layer, and the modified thermally conductive silicone protrudes from the outer surface of the shell.

[0027] Furthermore, this invention also provides a method for preparing a lithium-ion battery with high and low temperature resistance, comprising the following steps:

[0028] 1) The first and second grooves are formed on the outer surface of the housing by laser engraving, etching or stamping;

[0029] 2) Prepare low-temperature resistant material layer slurry and high-temperature resistant material layer slurry separately;

[0030] 3) Apply the low-temperature resistant material layer slurry to the first groove and apply the high-temperature resistant material layer slurry to the second groove;

[0031] 4) Dry the outer surface of the casing, then put the battery cell into the casing and seal it to obtain the lithium-ion battery.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] 1) This invention effectively solves the performance problem of lithium-ion batteries under extreme temperatures by respectively setting a low-temperature resistant material layer and a high-temperature resistant material layer on the outer surface of the battery casing, and greatly expands the battery's operating temperature range. Specifically, the phase transition temperature of the low-temperature resistant material layer is -12℃ to -15℃, and the phase transition temperature of the high-temperature resistant material layer is 57℃ to 62℃. This high-temperature resistant material layer is designed to absorb or release heat within a specific temperature range, enabling the lithium-ion battery to operate stably within the temperature range of -15℃ to 62℃.

[0034] 2) This invention provides a first groove and a second groove that are embedded side by side on the outer surface of the casing. The first groove and the second groove extend from the center of the outer surface of the casing in a U-shape to the edge of the outer surface of the casing. A low-temperature resistant material layer and a high-temperature resistant material layer are respectively provided in the first groove and the second groove. The outer surfaces of the low-temperature resistant material layer, the high-temperature resistant material layer and the casing are all on the same horizontal plane. Through the above structural design, the flatness and aesthetics of the battery appearance are guaranteed. The battery can effectively improve its high and low temperature resistance without increasing the wall thickness of the battery casing, thus ensuring that the volumetric energy density of the battery is not lost. Moreover, the U-shape design of the first groove and the second groove increases the heat exchange area and improves the temperature regulation efficiency. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of a lithium-ion battery according to an embodiment of the present invention;

[0036] Figure 2 This is a top view of a lithium-ion battery according to an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the structure of a lithium-ion battery according to another embodiment of the present invention;

[0038] Figure 4 This is a cross-sectional view of the buffer thermally conductive material layer in another embodiment of the present invention;

[0039] Figure 5 This is a schematic diagram of the structure of a lithium-ion battery according to another embodiment of the present invention;

[0040] Figure 6 This is a schematic diagram of the structure of a lithium-ion battery according to another embodiment of the present invention.

[0041] In the diagram: 1. Shell; 2. Low-temperature resistant material layer; 3. High-temperature resistant material layer; 4. Buffer and thermally conductive material layer; 41. First aluminum foam; 42. Second aluminum foam; 43. Third aluminum foam; 5. Thermal insulation and buffer material layer; 6. Modified thermally conductive silicone. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Please see the appendix Figures 1-2This embodiment provides a lithium-ion battery with high and low temperature resistance, comprising: a battery cell and a casing 1 for encapsulating the battery cell; wherein the battery cell comprises a positive electrode sheet, a separator and a negative electrode sheet stacked and wound in sequence; wherein the casing material can be made of aluminum, steel or aluminum alloy.

[0044] The outer surface of the housing 1 is provided with a first groove and a second groove, and the first groove and the second groove are embedded side by side on the outer surface of the housing 1. The first groove and the second groove extend from the center of the outer surface of the housing 1 to the edge of the outer surface of the housing 1 in a U-shape.

[0045] The first groove is provided with a low-temperature resistant material layer 2, the phase transition temperature of which is -12℃ to -15℃; the second groove is provided with a high-temperature resistant material layer 3, the phase transition temperature of which is 57℃ to 62℃.

[0046] The thickness of the low-temperature resistant material layer 2 is the same as the depth of the first groove, and the thickness of the high-temperature resistant material layer 3 is the same as the depth of the second groove; and the outer surfaces of the low-temperature resistant material layer 2, the high-temperature resistant material layer 3, and the shell 1 are on the same horizontal plane.

[0047] In one embodiment of this application, the low-temperature resistant material layer 2 comprises the following components in parts by weight: 40-50 parts of n-tetane, 25-35 parts of n-dodecane, 10-15 parts of 2-methylpentane, 3-5 parts of polyvinyl alcohol, 2-4 parts of graphene, 1-2 parts of nano-alumina, and 0.5-1 parts of silica aerogel.

[0048] Among them, n-tetane and n-dodecane serve as the main phase change materials, providing low-temperature phase change capability. Their combined use can regulate the phase change temperature and lower the freezing point. 2-Methylpentane further lowers the freezing point of the mixture, increases the material's fluidity, and improves low-temperature performance. Polyvinyl alcohol (PVA) acts as a thickener and structural stabilizer, improving the material's mechanical strength and shape stability. Graphene significantly improves the material's thermal conductivity, enhancing heat distribution within the phase change material. Nano-alumina strengthens the material's thermal stability, improving both thermal conductivity and mechanical strength. Silica aerogel provides excellent thermal insulation, reducing heat loss and improving the efficiency of the phase change material. The phase change temperature of this low-temperature resistant material layer 2 is -12℃ to -15℃. When this phase change temperature is reached, it can rapidly release heat, effectively regulating the battery temperature and improving the battery's low-temperature performance.

[0049] The preparation method of the low-temperature resistant material layer 2 is as follows:

[0050] (1) Mix n-tetane, n-dodecane and 2-methylpentane according to the specified ratio and stir until homogeneous at room temperature;

[0051] (2) Dissolve polyvinyl alcohol (PVA) in a small amount of deionized water, heat to 60°C and stir until completely dissolved;

[0052] (3) Slowly add the solution from step (2) to the mixture from step (1) and disperse it evenly for 30 minutes using a high-speed shear machine;

[0053] (4) Disperse graphene in a small amount of ethanol and sonicate for 20 minutes;

[0054] (5) Add the suspension, nano alumina and silica aerogel from step (4) to the mixture from step (3) in sequence, and continue high-speed shearing for 15 minutes to obtain a low-temperature resistant material layer slurry.

[0055] (6) Apply the low-temperature resistant material layer slurry to the first groove and dry it to obtain the low-temperature resistant material layer 2 with the required shape and thickness.

[0056] In one embodiment of this application, the high-temperature resistant material layer 3 comprises the following components in parts by weight: 45-55 parts of glyceryl stearate, 20-25 parts of palmitic acid, 10-15 parts of polyethylene glycol 4000, 3-5 parts of carbon nanotubes, 2-3 parts of boron nitride nanosheets, 1-2 parts of expanded graphite, and 0.5-1 parts of nano-magnesium oxide.

[0057] Among them, glyceryl stearate and palmitic acid serve as the main phase change materials, providing high-temperature phase change capability; their combined use can adjust the phase change temperature range. Polyethylene glycol 4000 regulates the phase change temperature, increases the material's heat capacity, and improves its heat storage capacity. Carbon nanotubes significantly improve the material's thermal conductivity, enhancing the rapid distribution of heat within the phase change material. Boron nitride nanosheets further enhance thermal conductivity and improve the material's thermal stability. Expanded graphite increases the material's specific surface area, improves heat exchange efficiency, and enhances its thermal conductivity and flame retardancy. Nano-magnesium oxide enhances the material's thermal stability and flame retardancy, improving its structural integrity at high temperatures. The phase change temperature of this high-temperature resistant material layer 3 is 57℃~62℃. When this phase change temperature is reached, it can rapidly absorb heat, effectively regulating the battery temperature and improving the battery's high-temperature resistance.

[0058] The preparation method of the high-temperature resistant material layer 3 is as follows:

[0059] (1) Mix octadecyl glycerol and palmitic acid according to the ratio, heat and melt them in an oil bath at 85-95℃, and stir evenly;

[0060] (2) Add polyethylene glycol 4000 to the molten mixture in step (1) and continue stirring until completely dissolved;

[0061] (3) Disperse carbon nanotubes and boron nitride nanosheets in a small amount of N-methylpyrrolidone (NMP) and sonicate for 30 minutes;

[0062] (4) Slowly add the suspension from step (3) to the molten mixture from step (2) and stir at high speed for 45 minutes;

[0063] (5) Add expanded graphite and nano-magnesium oxide, and continue to stir at high speed for 20 minutes to obtain a high-temperature resistant material slurry;

[0064] (6) Apply the high-temperature resistant material layer slurry to the second groove and dry it to obtain the high-temperature resistant material layer 3 with the required shape and thickness.

[0065] In one embodiment of this application, the depth of the first groove is H1, the depth of the second groove is H2, the thickness of the low-temperature resistant material layer 2 is h1, the thickness of the high-temperature resistant material layer 3 is h2, and the wall thickness of the shell 1 is H; wherein H, H1, H2, h1, and h2 satisfy the following relationships: h1 = h2 = H1 = H2; 0.2H ≤ H1 ≤ 0.6H; 0.2H ≤ H2 ≤ 0.6H. By precisely controlling the dimensional ratio of the first groove, the second groove, the low-temperature resistant material layer 2, the high-temperature resistant material layer 3, and the shell 1, the overall structural strength and high and low temperature resistance of the battery are effectively maintained. If the groove depth is too small, it will be difficult to support the high-temperature resistant material layer; if the groove depth is too large, it will affect the strength of the shell 1. Therefore, this dimensional ratio combination design ensures that the high-temperature resistant material layer does not affect the overall integration of the battery and can fully perform its function.

[0066] In one embodiment of this application, the projected area of ​​the low-temperature resistant material layer 2 is S1, the projected area of ​​the high-temperature resistant material layer 3 is S2, and the projected area of ​​the shell 1 is S; wherein S1, S2, and S satisfy the relationship: 0.6S≤S1+S2≤S. By controlling the sum of the projected areas of the low-temperature resistant material layer 2 and the high-temperature resistant material layer 3 to satisfy the above relationship, it is ensured that the coverage area of ​​the material layers is large enough to effectively regulate the temperature of the entire shell 1.

[0067] In one embodiment of this application, as shown in the appendix Figures 3-4 As shown, the outer surface of the housing 1 is also provided with a third groove, which is embedded side by side between the first groove and the second groove, and the third groove extends from the center of the outer surface of the housing 1 to the edge of the outer surface of the housing 1 in a U-shape.

[0068] The third groove is provided with a buffer thermal conductive material layer 4; the thickness of the buffer thermal conductive material layer 4 is greater than the thickness of the low temperature resistant material layer 2 or the high temperature resistant material layer 3, and the buffer thermal conductive material layer 4 protrudes from the outer surface of the shell 1.

[0069] The buffer thermal conductive material layer 4 includes a first aluminum foam 41, a second aluminum foam 42, and a third aluminum foam 43 arranged sequentially from the outside to the inside. The densities ρ1 of the first aluminum foam 41, ρ2 of the second aluminum foam 42, and ρ3 of the third aluminum foam 43 satisfy the relationship: ρ1 > ρ2 > ρ3. Furthermore, the first aluminum foam 41, the second aluminum foam 42, and the third aluminum foam 43 are all provided with staggered pore structures. The porosity Q1 of the first aluminum foam 41, the porosity Q2 of the second aluminum foam 42, and the porosity Q3 of the third aluminum foam 43 satisfy the relationship: Q1 < Q2 < Q3.

[0070] Each layer of aluminum foam can be installed in the third groove of the casing 1 through methods such as spraying or 3D printing. Aluminum foam is a novel lightweight functional material that combines the characteristics of metal and bubbles, giving it excellent energy absorption and buffering effects as well as thermal conductivity. It effectively absorbs the expansion force of the battery while minimizing the overall weight of the battery pack. During battery assembly, the three-layer aluminum foam structure with varying density and porosity can effectively absorb and disperse impact energy and has good thermal conductivity and heat dissipation, thus providing excellent buffering protection and thermal conductivity and heat dissipation performance. Specifically, the high-density and low-porosity first aluminum foam 41 can first receive and disperse external impact energy, reducing the direct transmission of impact force to the interior; the medium-density and high-porosity second aluminum foam 42 can further absorb and disperse the remaining impact energy. The low-density and high-porosity third aluminum foam 43 has extremely high energy absorption capacity and can ultimately absorb and disperse the remaining impact energy, protecting the individual battery cells. This application achieves the effect of absorbing and dispersing impact energy layer by layer by innovatively combining the porosity and density of each layer, thereby significantly improving the buffer protection performance of lithium-ion batteries and ensuring the safety and reliability of battery packs.

[0071] In one embodiment of this application, the density ρ1 of the first aluminum foam 41 is 0.8–1.2 g / cm³. 3 The preferred value is 0.95 g / cm³. 3 The density ρ2 of the second type of aluminum foam 42 is 0.5–0.8 g / cm³. 3 The preferred value is 0.65 g / cm³. 3 The density ρ3 of the third type of aluminum foam 43 is 0.2–0.5 g / cm³. 3 The preferred value is 0.35 g / cm³. 3 ;

[0072] The porosity Q1 of the first aluminum foam 41 is 45% to 60%, preferably 55%; the porosity Q2 of the second aluminum foam 42 is 60% to 75%, preferably 70%; and the porosity Q3 of the third aluminum foam 43 is 75% to 90%, preferably 85%.

[0073] In one embodiment of this application, as shown in the appendix Figure 5 As shown, the outer surface of the housing 1 is also provided with a third groove, which is embedded side by side between the first groove and the second groove, and the third groove extends from the center of the outer surface of the housing 1 to the edge of the outer surface of the housing 1 in a U-shape.

[0074] The third groove is provided with a heat insulation buffer material layer 5. The thickness of the heat insulation buffer material layer 5 is greater than the thickness of the low temperature resistant material layer 2 or the high temperature resistant material layer 3, and the heat insulation buffer material layer 5 protrudes from the outer surface of the shell 1.

[0075] The heat insulation and buffer material layer 5 is ceramicized silicone foam, which comprises the following components in parts by weight: 30-40 parts vinyl silicone oil, 10-20 parts silica, 20-50 parts nano-ceramic powder, 0.1-1.0 parts ethynylcyclohexanol, 1-10 parts hydrogen-containing silicone oil, 1-10 parts hydroxyl silicone oil, 0.1-1.0 parts platinum catalyst, 10-20 parts β-nepheline, and 1-8 parts halloysite nanotubes.

[0076] The ceramicized silicone foam provided by this invention not only has good elasticity under normal working conditions, providing excellent buffer protection for batteries during battery assembly, but also can rapidly form a self-supporting foam ceramic body at high temperatures, maintaining a high degree of cell structure retention, thereby exhibiting excellent heat insulation and flame retardant effects. Furthermore, it can withstand the burning of flames above 1300°C for a long time, effectively isolating the transmission of fire and temperature, controlling the fire range within a single battery area, and preventing adjacent batteries from catching fire.

[0077] Vinyl silicone oil serves as the primary polymer matrix, providing the necessary elasticity and flexibility in the foaming system. It can also enhance the material's mechanical strength by undergoing an addition reaction with hydrogen-containing silicone oil to form a cross-linked structure. Silica, acting as a reinforcing agent, increases the composite material's tear resistance and abrasion resistance while improving the silicone rubber's compression resistance, making the material less prone to deformation even under high loads. Nano-ceramic powder acts as a flame retardant, promoting the formation of a hard ceramic layer on the material surface at high temperatures, effectively preventing further propagation of flames and heat. Ethynylcyclohexanol acts as an inhibitor, controlling the polymerization rate and preventing structural instability caused by excessively rapid reactions. Hydrogen-containing silicone oil, as a cross-linking agent, reacts with vinyl silicone oil to form a silicone rubber network structure, enhancing the material's overall mechanical properties and thermal stability. Hydroxyl silicone oil acts as a foaming agent in this system, decomposing upon heating to produce gas and form a foam structure, thus providing good cushioning performance and low density. Platinum catalysts catalyze the addition crosslinking reaction of vinyl silicone oil and hydrogen-containing silicone oil, improving reaction efficiency and uniformity, and ensuring consistent material properties. β-Lithium nepheline, as a ceramic-forming agent, can promote the transformation of silicone rubber into ceramic at high temperatures, enhancing the material's high-temperature resistance and structural stability. Halloysite nanotubes, as a pore structure stabilizer, can form a uniformly distributed support structure in the material, enhancing pore structure stability and preventing collapse under high temperature or mechanical pressure.

[0078] Therefore, through these specific components and their synergistic effect, the silicone foam of this invention not only maintains excellent elasticity and flexibility, effectively protecting battery cells, but also significantly improves the material's performance under extreme conditions. Especially in thermal runaway fire scenarios, this material can rapidly form a self-supporting foam ceramic body, greatly enhancing its thermal insulation and flame retardant capabilities. This foam ceramic body can maintain its structural integrity and flame retardancy when subjected to high temperatures or direct flame irradiation, unlike traditional silicone foam which may crack, deform, collapse, or even pulverize under the same conditions, thus losing its protective ability.

[0079] The preparation method of this ceramicized silicone foam is as follows:

[0080] Step S1: Add vinyl silicone oil, silica, nano-ceramic powder, and β-nepheline to a kneader and knead into a ball at 100-150°C. Cool to obtain the base adhesive.

[0081] Step S2: Stir and mix hydroxyl silicone oil and halloysite nanotubes to obtain a foaming mixture; wherein the stirring speed is 23000-26000 r / min and the mixing time is 10-25 s;

[0082] Step S3: Add the above foaming mixture, ethynylcyclohexanol, hydrogen-containing silicone oil, and platinum catalyst to the base adhesive, mix evenly, and obtain the adhesive compound;

[0083] Step S4: The rubber compound is vulcanized and foamed using casting, calendering or molding processes to obtain ceramicized silicone foam.

[0084] The ceramicized silicone foam prepared by this invention has the following advantages:

[0085] 1) Excellent mechanical properties and elasticity: Due to the cross-linked structure of vinyl silicone oil and hydrogen-containing silicone oil, coupled with the reinforcing effect of silica, the silicone foam of the present invention has good elasticity and resistance to mechanical stress, which enables it to maintain its original shape and function after long-term use or repeated compression.

[0086] 2) Highly efficient flame retardant and heat insulation capabilities: The addition of nano-ceramic powder and β-lithium nepheline enables the material to quickly form a protective ceramic layer when subjected to high temperatures or flames. This structure not only effectively isolates the flames but also reduces heat transfer, protecting the internal structure from damage.

[0087] 3) Highly stable foam structure: The foam structure is formed by the gas generated from the decomposition of hydroxyl silicone oil, and its stability is enhanced by halloysite nanotubes, so that the foam is not easy to collapse even at high temperature and maintains a high cell structure retention rate.

[0088] 4) Excellent heat resistance: The controlled polymerization rate of ethynylcyclohexanol and the efficient catalytic effect of platinum catalyst ensure the uniform formation and stability of the silicone rubber network structure, thus maintaining performance even under extreme high temperature environments.

[0089] In one embodiment of this application, as shown in the appendix Figure 6 As shown, the outer surface of the housing 1 is also provided with a third groove, which is embedded side by side between the first groove and the second groove, and the third groove extends from the center of the outer surface of the housing 1 to the edge of the outer surface of the housing 1 in a U-shape.

[0090] The third groove is provided with modified thermally conductive silicone 6, the porosity of which is 65% to 85%, the thickness of which is greater than the thickness of the low-temperature resistant material layer 2 or the high-temperature resistant material layer 3, and the modified thermally conductive silicone 6 protrudes from the outer surface of the shell 1.

[0091] The modified thermally conductive silicone 6 with a porosity of 65% to 85% is placed in the third groove. It not only has good thermal conductivity, but also has a good energy absorption and buffering effect. In addition, when the battery is assembled, the modified thermally conductive silicone 6 can fix two adjacent batteries and absorb the battery expansion force. Moreover, its thermal conductivity can reach 6-10 W / (m·k), which can accelerate the heat conduction and dissipation of the battery pack at high temperature and reduce the internal temperature of the battery pack.

[0092] The preparation method of the modified thermally conductive silicone 6 is as follows:

[0093] 1) Boron nitride and KH570 silane coupling agent were dispersed in 100 ml of aqueous solution at a mass ratio of 10:1, with concentrations of 40 mg / ml and 4 mg / ml, respectively. The mixed dispersion was placed in a water bath for sonication at 0°C for 40 min. After centrifugation to remove excess solvent, the mixture was cooled and dried to obtain modified boron nitride powder.

[0094] 2) Modified boron nitride powder and graphene were dispersed in a mixed solvent of alcohol and water at a mass ratio of 1:5, with concentrations of 1.2 mg / ml and 6 mg / ml, respectively. At the same time, 2 mg / ml of carbon nanotubes were added. The mixture was ultrasonically sonicated at 1200W for 10 min using an ultrasonic cell disruptor to obtain graphene slurry.

[0095] 3) Immerse polyurethane foam in 2 mol / L NaOH solution, treat it in 40℃ warm water for 3.5 h, and then soak it in 5 mg / ml aniline methyltriethoxysilane aqueous solution for 24 h to obtain modified polyurethane porous foam.

[0096] 4) The modified polyurethane porous foam structure was impregnated in the uniform graphene slurry prepared above, and ultrasonicated in a water bath at 0°C for 20 min. It was then dried at 60°C, and then heated from 60°C to 200°C at a rate of 15°C per minute, and then heated from 200°C to 380°C at a rate of 3°C per minute for 30 min to remove the porous material, thus obtaining a three-dimensional porous graphene-boron nitride composite material.

[0097] 5) The three-dimensional porous graphene-boron nitride composite material obtained above is immersed in silicone (Wacker SEMICOSIL 9212), the air bubbles are removed by vacuuming, and it is placed in an oven at 125°C for curing for 15 minutes to obtain modified thermally conductive silicone 6.

[0098] Furthermore, this invention also provides a method for preparing a lithium-ion battery with high and low temperature resistance, comprising the following steps:

[0099] 1) A first groove and a second groove are formed on the outer surface of the housing 1 by laser engraving, etching or stamping;

[0100] 2) Prepare low-temperature resistant material layer slurry and high-temperature resistant material layer slurry separately;

[0101] 3) Apply the low-temperature resistant material layer slurry to the first groove and apply the high-temperature resistant material layer slurry to the second groove;

[0102] 4) Dry the outer surface of the casing 1, then put the battery cell into the casing for encapsulation, inject electrolyte, and form to obtain the lithium-ion battery.

[0103] This preparation method uses laser engraving, etching, or stamping to create grooves on the outer surface of the casing, which allows for precise control of the size and shape of the grooves, ensuring uniform coating of the material layers. The process of coating the low-temperature resistant material layer slurry and the high-temperature resistant material layer slurry can be adjusted and optimized as needed to ensure the quality and performance of the material layers. Finally, through drying and encapsulation processes, a tight bond between the material layers and the casing is ensured, improving the overall performance and reliability of the battery.

[0104] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0105] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A lithium ion battery with high and low temperature resistance, characterized in that, The application relates to a battery cell and a shell for packaging the battery cell. The shell is provided with a first groove and a second groove which are embedded side by side on the outer surface of the shell and extend in a meandering manner from the center of the outer surface of the shell to the edge of the outer surface of the shell. The first groove is provided with a low-temperature-resistant material layer, and the phase transition temperature of the low-temperature-resistant material layer is -12 DEG C to -15 DEG C; the second groove is provided with a high-temperature-resistant material layer, and the phase transition temperature of the high-temperature-resistant material layer is 57 DEG C to 62 DEG C. The thickness of the low-temperature-resistant material layer is the same as the depth of the first groove, the thickness of the high-temperature-resistant material layer is the same as the depth of the second groove, and the outer surfaces of the low-temperature-resistant material layer, the high-temperature-resistant material layer and the shell are on the same horizontal plane. The low-temperature-resistant material layer comprises the following components in a weight ratio: 40-50 parts of n-tridecane, 25-35 parts of n-dodecane, 10-15 parts of 2-methylpentane, 3-5 parts of polyvinyl alcohol, 2-4 parts of graphene, 1-2 parts of nano-aluminum oxide and 0.5-1 part of silica aerogel. The high-temperature-resistant material layer comprises the following components in a weight ratio: 45-55 parts of glyceryl octadecanoate, 20-25 parts of palmitic acid, 10-15 parts of polyethylene glycol 4000, 3-5 parts of carbon nanotubes, 2-3 parts of boron nitride nanosheet, 1-2 parts of expanded graphite and 0.5-1 part of nano-magnesium oxide. The depth of the first groove is H1, the depth of the second groove is H2, the thickness of the low-temperature-resistant material layer is h1, the thickness of the high-temperature-resistant material layer is h2, and the wall thickness of the shell is H; wherein H, H1, H2, h1 and h2 satisfy the relationship: h1 = h2 = H1 = H2; 0.2H <= H1 <= 0.6H; 0.2H <= H2 <= 0.6H.

2. The lithium ion battery with high and low temperature resistance according to claim 1, characterized in that: The normal projection area of the low-temperature-resistant material layer is S1, the normal projection area of the high-temperature-resistant material layer is S2, and the normal projection area of the shell is S; wherein S1, S2 and S satisfy the relationship: 0.6S <= S1 + S2 <= S. 3.The lithium ion battery with high and low temperature resistance of claim 1, wherein: The outer surface of the shell is further provided with a third groove which is embedded side by side between the first groove and the second groove and extends in a meandering manner from the center of the outer surface of the shell to the edge of the outer surface of the shell.

4. The lithium ion battery with high and low temperature resistance according to claim 1, characterized in that: The third groove is provided with a buffer heat-conducting material layer. The thickness of the buffer heat-conducting material layer is greater than the thickness of the low-temperature-resistant material layer or the high-temperature-resistant material layer, and the buffer heat-conducting material layer protrudes from the outer surface of the shell. ​ The buffer heat-conducting material layer comprises first, second and third foamed aluminum arranged in sequence from outside to inside, the density p1 of the first foamed aluminum, the density p2 of the second foamed aluminum and the density p3 of the third foamed aluminum satisfy the relationship: p1>p2>p3; and the first, second and third foamed aluminum are all provided with staggered arranged air hole structures, the porosity Q1 of the first foamed aluminum, the porosity Q2 of the second foamed aluminum and the porosity Q3 of the third foamed aluminum satisfy the relationship: Q1<Q2<Q3.

5. The lithium ion battery with high and low temperature resistance according to claim 4, characterized in that: The density p1 of the first aluminum foam is 0.8-1.2 g / cm 3 ; the density p2 of the second aluminum foam is 0.5-0.8 g / cm 3 ; and the density p3 of the third aluminum foam is 0.2-0.5 g / cm 3 . The porosity Q1 of the first foamed aluminum is 45% to 60%; the porosity Q2 of the second foamed aluminum is 60% to 75%; and the porosity Q3 of the third foamed aluminum is 75% to 90%.

6. The lithium ion battery with high and low temperature resistance according to claim 1, characterized in that: The outer surface of the shell is further provided with a third groove, the third groove is embedded side by side between the first groove and the second groove, and the third groove extends in a meandering manner from the center of the outer surface of the shell to the edge of the outer surface of the shell; The third groove is provided with a heat-insulating buffer material layer, the thickness of the heat-insulating buffer material layer is greater than the thickness of the low-temperature-resistant material layer or the high-temperature-resistant material layer, and the heat-insulating buffer material layer protrudes from the outer surface of the shell; The heat-insulating buffer material layer is ceramicized silica gel foam, which comprises the following components in a weight ratio: 30-40 parts of vinyl silicone oil, 10-20 parts of white carbon black, 20-50 parts of nano ceramic powder, 0.1-1.0 parts of ethynylcyclohexanol, 1-10 parts of hydrogen-containing silicone oil, 1-10 parts of hydroxyl silicone oil, 0.1-1.0 parts of platinum catalyst, 10-20 parts of β-lithia, and 1-8 parts of halloysite nanotube.

7. The lithium ion battery with high and low temperature resistance according to claim 1, characterized in that: The outer surface of the shell is further provided with a third groove, the third groove is embedded side by side between the first groove and the second groove, and the third groove extends in a meandering manner from the center of the outer surface of the shell to the edge of the outer surface of the shell; The third groove is provided with modified heat-conducting silica gel, the porosity of the modified heat-conducting silica gel is 65% to 85%, the thickness of the modified heat-conducting silica gel is greater than the thickness of the low-temperature-resistant material layer or the high-temperature-resistant material layer, and the modified heat-conducting silica gel protrudes from the outer surface of the shell.

8. The method for preparing a lithium ion battery with high and low temperature resistance according to any one of claims 1-7, characterized in that, The method comprises the following steps: 1) setting a first groove and a second groove on the outer surface of the shell by laser engraving, etching or stamping; 2) preparing a low-temperature-resistant material layer slurry and a high-temperature-resistant material layer slurry respectively; 3) coating the low-temperature-resistant material layer slurry in the first groove and the high-temperature-resistant material layer slurry in the second groove; 4) drying the outer surface of the shell, and then packaging the electric core in the shell to obtain the lithium ion battery.

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