A battery case

Abstract

The utility model provides a kind of battery shell, battery shell includes: shell body, the shell body has opening, the shell body includes bottom wall and the sidewall being arranged around the bottom wall;Thermal silica gel layer, the thermal silica gel layer includes first thermal silica gel layer and second thermal silica gel layer, the first thermal silica gel layer covers the inner surface of the bottom wall, the second thermal silica gel layer at least covers the partial area of the inner surface of the sidewall, and the edge of the second thermal silica gel layer is close to the edge of the first silica gel layer and is connected.The utility model effectively blocks the electron conduction path between aluminum shell and negative electrode, prevents the safety problem caused by electrochemical corrosion;At the same time, its high thermal conductivity characteristics significantly improve battery heat dissipation efficiency, avoid local overheating;And improve the overall compression strength and durability of shell, also take into account lightweight and space utilization.

Description

Technical Field

[0001] This utility model belongs to the field of battery technology, and specifically relates to a battery casing. Background Technology

[0002] If an aluminum-cased lithium battery experiences an internal short circuit, causing the casing to become conductive with the negative electrode, it can trigger electrochemical corrosion, leading to aluminum casing pulverization and safety risks. Current technologies generally use an inner surface insulating layer to prevent corrosion, but this often results in poor thermal conductivity, requires thicker casings, or affects welding, making it difficult to balance heat dissipation, energy density, and production reliability. Utility Model Content

[0003] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a battery casing that solves the problem that the prior art generally uses an inner surface insulation layer to prevent corrosion, but this often results in poor thermal conductivity, thickened casing, or interference with welding, making it difficult to balance heat dissipation, energy density, and production reliability.

[0004] To achieve the above and other related objectives, this utility model provides a battery casing, comprising:

[0005] A housing body having an opening, the housing body including a bottom wall and side walls surrounding the bottom surface;

[0006] A thermally conductive silicone layer, comprising a first thermally conductive silicone layer and a second thermally conductive silicone layer, wherein the first thermally conductive silicone layer covers the inner surface of the bottom wall, and the second thermally conductive silicone layer covers at least a portion of the inner surface of the side wall, and the edge of the second thermally conductive silicone layer near the bottom wall is connected to the edge of the first silicone layer.

[0007] In one embodiment of this utility model, the material of the thermally conductive silicone layer includes an organosilicon matrix and a thermally conductive filler. The organosilicon matrix includes one or more of vinyl silicone oil, methyl silicone oil, methyl vinyl silicone rubber, methyl phenyl silicone resin, and fluorosiloxane. The thermally conductive filler includes one or more of boron nitride, aluminum nitride, aluminum oxide, zinc oxide, and magnesium oxide. The organosilicon matrix accounts for 10wt% to 50wt%, and the thermally conductive filler accounts for 50wt% to 90wt%.

[0008] In one embodiment of this utility model, the thickness of the thermally conductive silicone layer is t, wherein 5μm≤t≤500μm.

[0009] In one embodiment of the present invention, along the direction from the opening to the bottom wall, the sidewall sequentially includes an uncoated area and a coated area, wherein the uncoated area is not covered by the second thermally conductive silicone layer, and the coated area is covered by the second thermally conductive silicone layer.

[0010] In one embodiment of this utility model, when the battery is placed upright, the lowest point of the uncoated area is higher than the liquid level of the electrolyte in the battery.

[0011] In one embodiment of this utility model, the height of the uncoated area is H, wherein 1mm≤H≤100mm.

[0012] In one embodiment of the present invention, the inner surface of the adhesive-coated area is thinned outward relative to the inner surface of the uncoated area to form a groove, and the thickness of the second thermally conductive silicone layer is greater than or equal to the depth of the groove.

[0013] In one embodiment of the present invention, an inner shell is further included, the inner shell covering the side of the thermally conductive silicone layer opposite to the shell body.

[0014] In one embodiment of the present invention, the wall thickness of the shell body accounts for 20% to 80% of the total wall thickness of the shell body and the inner shell.

[0015] In one embodiment of this utility model, the viscosity of the thermally conductive silicone layer before heating and curing is 100 mPa·s to 30000 mPa·s.

[0016] This invention achieves synergistic optimization of insulation, mechanical strength, and thermal conductivity by incorporating a specifically structured thermally conductive silicone layer inside the battery casing. This layer, composed of a high-insulation silicone material and a high-thermal-conductivity filler, effectively blocks the electron conduction path between the aluminum casing and the negative electrode, preventing safety issues caused by electrochemical corrosion. Simultaneously, its high thermal conductivity significantly improves battery heat dissipation efficiency, avoiding localized overheating. Furthermore, through a rational formulation, thin-layer design, and multi-layer composite structure, it not only enhances the overall compressive strength and durability of the casing but also balances lightweight design and space utilization, fundamentally achieving a balance between battery safety, thermal management performance, and structural reliability. Specifically, it offers the following beneficial effects:

[0017] This invention effectively blocks the electrochemical corrosion path, improving battery safety and cycle life. Specifically, by covering the bottom and lower side walls of the casing with a thermally conductive silicone layer made of highly insulating organic silicone material, a reliable electronic barrier is formed, fundamentally preventing abnormal conduction between the aluminum casing and the negative electrode caused by production impurities, burrs, or assembly deviations, and significantly reducing safety risks such as leakage and thermal runaway caused by corrosion.

[0018] This invention enables efficient heat conduction and optimizes battery thermal management performance. Specifically, it employs a thermally conductive silicone layer composed of a high thermal conductivity filler and an organic silicone matrix. Its thermal conductivity is much higher than that of traditional PET / PP films or multi-layer organic coatings. This design significantly reduces the thermal resistance between the cell and the casing, promotes rapid heat transfer from the inside to the casing, and improves overall heat dissipation efficiency.

[0019] The partitioned coating design of this utility model takes into account both insulation protection and welding process compatibility. By setting a coated area and an uncoated area on the side wall, this design ensures that the laser welding area of ​​the top cover is an exposed metal surface, avoiding carbonization, blistering or gas release of the silicone material during high-temperature welding, thereby ensuring weld quality, airtightness and connection strength, and completely solving the process problem of traditional coatings interfering with welding.

[0020] This invention ensures insulation and thermal conductivity by thinning part of the shell and coating it with a thermally conductive silicone layer. At the same time, it also improves energy density and space utilization. The thinning design minimizes the occupation of internal battery space, which is beneficial to improving electrode material filling rate and volumetric energy density.

[0021] This invention enhances mechanical strength and improves overall reliability through a multi-layered composite structure. The design of the inner shell structure forms a three-layer composite system: outer shell – thermally conductive silicone layer – inner shell. This design not only protects the thermally conductive silicone layer from mechanical damage to the electrode components but also significantly improves the shell's resistance to pressure, bending, and fatigue through the coordinated load-bearing capacity of the inner and outer shells. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0023] Figure 1 This is a schematic diagram of the battery casing in one embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the thinning of the battery casing portion in one embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of adding an inner shell to the battery casing in one embodiment of the present invention.

[0026] Label Explanation:

[0027] 11. Bottom wall; 12. Side wall; 121. Uncoated area; 122. Coated area; 101. Opening; 20. Thermally conductive silicone layer; 30. Inner shell. Detailed Implementation

[0028] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0029] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0030] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the present invention.

[0031] Aluminum casings, as core structural components of power and energy storage lithium batteries, are widely used in new energy vehicles, energy storage power stations, and other fields. However, they face the risk of electrochemical corrosion during long-term use and production, a problem directly related to the battery's safety, lifespan, and reliability. In normal design, square aluminum casings are typically kept at a similar potential to the battery's positive electrode via electrical connection, maintaining a thermodynamically stable state and making them less prone to reaction. However, if impurities or burrs during production cause electronic channels to open up the aluminum casing to the negative electrode, the aluminum casing's potential is forcibly lowered until it reaches the lithium-aluminum alloy formation potential. This process triggers a series of chain reactions, such as lithium embedding into the aluminum lattice, leading to lattice expansion; aluminum crystal structure cracking, pulverization, and surface blackening; and the formation of porous or cracked structures, exacerbating electrolyte penetration and other problems, thus causing safety issues. Existing technologies utilize methods such as photosensitive resin composite coatings, PET / PP plastic films, or multilayer organic coatings on the inner surface of the aluminum casing to block electrochemical corrosion pathways. However, these methods generally suffer from poor thermal conductivity, impaired battery heat dissipation, reduced energy density, increased casing thickness, or interference with the top cover welding process. They also struggle to balance insulation, thermal management, structural compactness, and production compatibility, thus hindering the development of high-safety, high-energy-density batteries. Through further research, the applicant provides a battery casing and battery in this application that prevents electrochemical corrosion caused by conduction between the casing and the negative electrode, while simultaneously enhancing the strength and thermal conductivity of the aluminum casing.

[0032] Please see Figure 1As shown, this utility model proposes a battery casing and a battery that can effectively block the electrochemical corrosion path between the casing and the negative electrode while taking into account the thermal conductivity, mechanical strength, thermal stability, and compatibility with subsequent packaging processes of the materials, fundamentally improving the safety and reliability of the battery. In this embodiment, the battery casing includes a casing body and a thermally conductive silicone layer 20. The casing body includes a bottom wall 11 and a side wall 12. The side wall 12 extends upward from the edge of the bottom wall 11 and surrounds the bottom wall 11 to form a receiving cavity. The casing body has an opening 101 located at the top of the casing for cell insertion and subsequent top cover welding and sealing. The thermally conductive silicone layer 20 includes a first thermally conductive silicone layer 21 and a second thermally conductive silicone layer 22. The first thermally conductive silicone layer 21 covers the inner surface of the bottom wall 11, and the second thermally conductive silicone layer 22 covers at least a portion of the inner surface of the side wall 12. The edge of the second thermally conductive silicone layer 22 near the bottom wall 11 is connected to the edge of the first thermally conductive silicone layer 21. Understandably, the thermally conductive silicone layer 20 is composed of an organosilicon material with good insulation properties and high thermal conductivity, ensuring excellent electrical insulation within the battery's operating voltage range. This effectively blocks the electron conduction path between the casing and the negative electrode, preventing the aluminum casing potential from being abnormally pulled down, avoiding electrochemical corrosion, and improving the battery's long-term safety and cycle life. Simultaneously, the thermally conductive silicone layer 20 has a high thermal conductivity, for example, 1.0–3.0 W / (m·K), significantly higher than traditional organic coatings or plastic films. This effectively promotes the transfer of heat from the battery's interior to the casing, improving overall heat dissipation efficiency and facilitating thermal management of the battery under high-rate charging / discharging or high-temperature conditions.

[0033] Please see Figure 1 As shown, in this embodiment, the material of the thermally conductive silicone layer 20 includes an organosilicon matrix and a thermally conductive filler. The organosilicon matrix is ​​selected from one or more of vinyl silicone oil, methyl silicone oil, methyl vinyl silicone rubber, methyl phenyl silicone resin, and fluorosiloxanes. These materials possess excellent heat resistance, weather resistance, flexibility, and electrical insulation properties. They maintain structural stability even at high temperatures and are not prone to aging or cracking, making them suitable as substrates for functional coatings inside batteries. The thermally conductive filler is selected from one or more of boron nitride (BN), aluminum nitride (AlN), aluminum oxide (Al₂O₃), zinc oxide (ZnO), and magnesium oxide (MgO). These fillers have high thermal conductivity, low electrical conductivity, and good chemical inertness, significantly improving the overall thermal conductivity of the composite material without sacrificing insulation performance.

[0034] Furthermore, in this embodiment, the weight ratios of the components in the thermally conductive silicone layer 20 are as follows: the silicone matrix accounts for 10wt% to 50wt%, and the thermally conductive filler accounts for 50wt% to 90wt%. The silicone matrix plays a role in bonding, film formation, and buffering. If its content is too low, for example, below 10wt%, it will result in insufficient coating and connection between filler particles, leading to problems such as cracking, decreased adhesion, and insufficient flexibility in the coating. During battery assembly or use, local peeling may occur, exposing the aluminum shell substrate and losing its insulating protection function. At the same time, an excessively low silicone matrix content will also reduce the material's workability, which is not conducive to uniform film formation in spraying or printing processes. Conversely, if the silicone matrix content is too high, for example, exceeding 50wt%, although the flexibility and process adaptability of the coating are improved, it will significantly dilute the volume concentration of the thermally conductive filler, resulting in a decrease in overall thermal conductivity and failing to meet the high-efficiency heat dissipation requirements of high-power batteries. When the thermally conductive filler content is below 50 wt%, heat transfer mainly relies on the low thermal conductivity of the silicone matrix, resulting in a low overall thermal conductivity of the composite coating, which is insufficient to meet the heat dissipation requirements of high-power charging and discharging of the power battery. If the filler content exceeds 90 wt%, the matrix phase is insufficient to completely cover the particles, increasing the brittleness of the coating. This makes it prone to microcracks during curing or assembly, leading to decreased adhesion or even localized peeling, which in turn affects the insulation reliability and long-term stability.

[0035] Preferably, in this embodiment, the weight ratio of each component in the thermally conductive silicone layer 20 is as follows: the organic silicone matrix accounts for 15wt% to 25wt%, and the thermally conductive filler accounts for 75wt% to 85wt%. It is understood that at this ratio, the organic silicone matrix is ​​sufficient to fully wet and coat the high proportion of thermally conductive filler particles, forming a uniform and continuous three-dimensional network structure. The organic silicone matrix effectively fills the gaps between the filler particles, enhancing the density and interfacial adhesion of the coating, preventing localized peeling due to particle loosening or microcrack expansion, thereby ensuring the structural integrity of the thermally conductive silicone layer 20 during battery assembly and long-term service. Simultaneously, the thermal conductivity of the thermally conductive silicone layer with a high proportion of 75wt% to 85wt% thermally conductive filler is significantly higher than that of traditional organic insulating coatings and plastic insulating layers, effectively promoting rapid heat diffusion from the battery interior to the bottom of the casing, reducing the temperature difference between the cell center and the casing, and improving overall thermal management efficiency.

[0036] Please see Figure 1As shown, in this embodiment, the thickness t of the thermally conductive silicone layer 20 is set to 5μm≤t≤500μm. It is understood that when the thickness of the thermally conductive silicone layer 20 is less than 5μm, the coating is difficult to form a continuous and dense covering layer, easily resulting in defects such as pinholes, breaks, or localized thin areas, leading to a decrease in electrical insulation performance and an inability to effectively block the electronic conduction path between the casing and the negative electrode. During battery assembly, the electrode assembly may experience cracking of the ultra-thin coating due to localized pressure, exposing the aluminum casing and triggering a lithium intercalation reaction, inducing electrochemical corrosion. Furthermore, excessively thin coatings require extremely high uniformity of filler distribution, have a narrow process window, and are not conducive to large-scale stable production. While a thickness exceeding 500μm further improves insulation reliability, it brings a series of negative impacts: on the one hand, an excessively thick coating significantly occupies internal battery space, reducing the filling volume of the electrode assembly and causing a decrease in battery volumetric energy density; on the other hand, an excessively thick structure increases thermal resistance, hindering rapid heat conduction from the cell to the casing and weakening the heat dissipation effect. Preferably, the thickness of the thermally conductive silicone layer 20 is controlled between 30 μm and 50 μm. At this thickness, even with a small amount of micron-sized impurities or burrs, the coating can still maintain complete coverage, meeting the high-voltage insulation requirements of the power battery. The thin layer design of 30–50 μm significantly shortens the heat conduction path, and combined with the introduction of high thermal conductivity fillers, the coating achieves efficient heat conduction under low thermal resistance conditions. This thickness occupies minimal internal space in the battery, which is beneficial to improving the battery's energy density. In summary, the thermally conductive silicone layer 20 at this thickness not only ensures comprehensive electrochemical protection of the aluminum shell surface, preventing corrosion failure caused by the connection between the shell and the negative electrode, but also takes into account heat dissipation efficiency, energy density, and manufacturing feasibility.

[0037] Please see Figure 1 As shown, in this embodiment, along the direction from the opening 101 to the bottom wall 11, the side wall 12 sequentially includes an uncoated area 121 and a coated area 122. The uncoated area 121 does not cover the second thermally conductive silicone layer 22, while the coated area 122 is covered by the second thermally conductive silicone layer 21. That is, the second thermally conductive silicone layer 22 does not continuously cover the entire inner surface of the side wall 12, but a certain height of uncoated area 121 is reserved in the side wall area near the opening 101 to avoid the coating interfering with the welding process during the top cover encapsulation process.

[0038] Specifically, during the battery encapsulation stage, the top cover and the opening of the casing body need to be connected in an airtight manner through laser welding or resistance welding. If the thermally conductive silicone layer 20 extends to the welding area near the opening, the silicone material may carbonize, blister, or release volatile gases during the high-temperature welding process. This not only affects the weld formation quality but may also lead to incomplete welding, missed welding, or sealing failure. In severe cases, it may cause safety problems such as battery leakage or internal short circuit. In addition, carbonized residues may become conductive impurities, increasing the risk of short circuits between the casing and internal components.

[0039] It is understandable that the internal space of the battery corresponding to the uncoated area 121 is typically covered and isolated by the plastic and Mylar film under the cover plate. These structural components themselves have excellent electrical insulation properties and mechanical strength, effectively blocking the electrical connection between the top cover metal parts and the casing, while also wrapping and protecting the edges of the electrode assembly to prevent electrode burrs from piercing or slipping into the casing. Therefore, although the uncoated area is bare aluminum, because its location is far from the active electrode area and it is tightly covered by multiple insulating structures, the risk of short circuits in actual operation is extremely low. In summary, by setting a partitioned structure of coated and uncoated areas in this embodiment, this utility model ensures the insulation and thermal conductivity of critical contact areas while taking into account the process compatibility and sealing reliability of the top cover welding, achieving a unity of safety, reliability, and manufacturability.

[0040] In this embodiment, when the battery is placed upright, the uncoated area 121 is positioned above the electrolyte surface. Specifically, the lowest point of the uncoated area 121 is higher than the electrolyte level in the battery. After the battery cell is filled with electrolyte and allowed to settle, the electrolyte level is typically located in the upper middle part of the battery cell assembly. Since the uncoated area 121 is located above the electrolyte level, the exposed aluminum material cannot directly contact the electrolyte, effectively preventing localized electrochemical reactions that may occur in the aluminum casing within the electrolyte environment. This further enhances the long-term chemical stability and safety. It is understood that the height of the uncoated area 121 can also be dynamically adjusted according to the electrolyte volume and level of different battery models to ensure it remains within a safe area above the electrolyte surface.

[0041] Please see Figure 1As shown, in this embodiment, the height H of the uncoated area 121 satisfies: 1mm ≤ H ≤ 100mm, to ensure the reliability of the top cover welding, while also taking into account insulation protection and space utilization efficiency. It is understandable that when the height H of the uncoated area 121 is less than 1mm, the uncoated area is too narrow, making it difficult to ensure that the welding interface is completely free of thermally conductive silicone residue in actual production. Under the high temperature of laser welding, the residual silicone may carbonize, bubble, or release gas, causing weld porosity, incomplete welding, or spatter, severely affecting welding strength and airtightness, and increasing the risk of leakage or internal short circuits. Conversely, when the height H of the uncoated area 121 exceeds 100mm, although it can fully guarantee the welding process window, it excessively compresses the coverage area of ​​the coated area on the sidewall, resulting in insufficient insulation protection of the upper part of the electrode assembly in contact with the shell. Especially under conditions such as cell expansion, vibration, or assembly misalignment, the electrode sheet or metal tab may contact the unprotected exposed aluminum shell, increasing the probability of local short circuits. Preferably, the height H of the uncoated area 121 is controlled within the range of 5mm≤H≤20mm, which can minimize the interference of the thermally conductive silicone layer 20 on the welding process, while ensuring that the thermally conductive silicone layer 20 blocks the electronic conduction path between the shell and the negative electrode and ensures the thermal conductivity of the thermally conductive silicone layer 20.

[0042] In this embodiment, the thermally conductive silicone can be coated onto the inner surface of the aluminum shell using various methods such as spraying, brushing, or pressure coating. After coating, the thermally conductive silicone needs to be cured by heating to form a stable thermally conductive silicone layer 20. The curing temperature is controlled between 80℃ and 180℃, preferably between 120℃ and 150℃. It is understood that when the temperature is below 80℃, the cross-linking reaction of the silicone matrix is ​​insufficient, resulting in insufficient coating hardness, poor adhesion, and decreased chemical resistance. On the other hand, temperatures above 180℃ may cause excessive growth of the oxide layer on the aluminum shell surface or lead to localized thermal stress deformation, affecting the dimensional accuracy of the shell. Preferably, the curing temperature is set between 120℃ and 150℃ to ensure both cross-linking density and mechanical strength while avoiding thermal damage to the aluminum alloy substrate.

[0043] In this embodiment, the viscosity of the thermally conductive silicone layer 20 before heating and curing is 100 mPa·s to 30000 mPa·s. If the viscosity is less than 100 mPa·s, the material has excessive fluidity, which can easily cause sagging, uneven thickness, or liquid accumulation at the bottom on the vertical sidewalls, leading to coating defects. When the viscosity is greater than 30000 mPa·s, it is difficult to disperse evenly by spraying or screen printing, which can easily cause problems such as gun clogging, stringing, or incomplete coverage. Preferably, controlling the viscosity between 3000 mPa·s and 10000 mPa·s can achieve the best workability. The material has good thixotropic properties, which can stably adhere to the vertical sidewalls without sagging, and can also be evenly spread by conventional coating equipment to form a wet film with high thickness consistency.

[0044] Please see Figure 2 As shown, in this embodiment, the inner surface of the glued area 122 is thinned towards the outside of the shell relative to the inner surface of the uncoated area 121 to form a groove. That is, the inner wall of the shell body of the glued area is locally thinned so that the wall thickness of the area is slightly lower than that of the uncoated area 121. The second thermally conductive silicone layer 22 is filled in the groove and its thickness is greater than or equal to the depth of the groove. It is understandable that by setting a groove in the coating area 122, an embedded space is reserved inside the casing to accommodate the second thermally conductive silicone layer 22. When the second thermally conductive silicone layer 22 fills the groove, its outer surface can be flush with or higher than the inner surface of the uncoated area 12, thereby maintaining the overall flatness of the internal contour of the battery casing and avoiding problems such as difficulty in assembling electrode components, uneven force, or local compression caused by coating protrusion. Furthermore, this structure achieves efficient utilization of the internal space of the casing. Compared to the coating directly covering the complete inner surface, which would occupy additional internal battery volume and reduce the filling space of electrode materials, this embodiment uses a groove to accommodate the thermally conductive silicone layer 20, minimizing the impact on the usable volume of the battery without affecting the coating function, which is beneficial to improving the volumetric energy density.

[0045] Please see Figure 3 As shown, in another embodiment, the battery housing further includes an inner housing 30, which covers the side of the thermally conductive silicone layer 20 away from the housing body, i.e., the side of the thermally conductive silicone layer 20 facing the internal space of the battery, forming a multi-layer composite structure of housing body—thermally conductive silicone layer 20—inner housing 30. This not only achieves synergy between electrochemical corrosion protection and thermal management functions, but also enhances the mechanical integrity and assembly compatibility of the overall structure through the inner housing 30. While ensuring the insulation and thermal conductivity of the thermally conductive silicone layer 20, it also effectively guarantees the strength of the housing. By covering the outer surface of the thermally conductive silicone layer 20 with an inner housing 30, direct contact between the electrode components and the functional coating can be effectively isolated, avoiding mechanical damage and significantly improving the long-term reliability and durability of the coating. Simultaneously, as the first physical barrier inside the battery, the inner housing further enhances the ability to block potential short-circuit sources such as burrs and foreign objects, improving the battery's safety margin.

[0046] For example, the thickness of the housing body can be reduced compared to the traditional housing. After applying adhesive, an aluminum shell (inner housing 30) is pressed onto the inner surface of the thermally conductive silicone to keep the overall thickness unchanged. Through this structural design, the overall external dimensions and total wall thickness of the battery housing remain unchanged, which is compatible with the existing module design and does not require changes to the external structural matching relationship. The inner housing 30 is used to house the electrode assembly. The housing body and the inner housing 30 provide support and heat dissipation. The thermally conductive silicone layer 20 achieves the dual functions of insulation and heat conduction.

[0047] Please see Figures 1 to 3As shown, in this embodiment, the shell body serves as the outer shell, and its thickness accounts for 20% to 80% of the total thickness of the shell body and the inner shell 30. When the thickness of the shell body is less than 20%, its rigidity and deformation resistance as an external load-bearing structure decrease significantly, making it difficult to effectively resist external mechanical impacts or compressive stress during battery module assembly. Furthermore, an excessively thin metal substrate also affects the heat transfer efficiency from the inside to the outside shell, weakening the overall heat dissipation performance. Conversely, when the thickness of the shell body exceeds 80%, the inner shell 30 becomes correspondingly too thin, making it difficult to fully utilize its physical protection function for the thermally conductive silicone layer 20. An excessively thin inner shell 30 is prone to localized yielding, wrinkling, or cracking during electrode assembly or battery cycle expansion, losing its flat support and insulation function for the internal battery cells, increasing the risk of short circuits. Preferably, the thickness of the shell body accounts for 40% to 60% of the total thickness of the shell body and the inner shell. Under this ratio, the shell body and the inner shell 30 work together to bear internal and external loads, the stress distribution is more uniform, and the overall compressive strength, bending strength and fatigue resistance of the shell are significantly improved. This makes it suitable for power batteries and energy storage systems under high cycle and high vibration conditions.

[0048] This invention also proposes a battery comprising a battery casing as described in the above embodiments. The battery can be a prismatic battery or a cylindrical battery.

[0049] This utility model also proposes a method for preparing a battery casing:

[0050] Step 1: Mix methyl vinyl silicone and boron nitride at a certain mass ratio to obtain a uniformly dispersed thermally conductive silicone.

[0051] Step 2: Apply the thermally conductive silicone prepared in Step 1 to the inner surface of the aluminum shell using a spraying device. Spray a certain thickness and leave a certain height of uncoated area 121 at the opening of the aluminum shell.

[0052] Step 3: The aluminum shell with thermally conductive silicone coating on the inner surface prepared in Step 2 is cured by heating.

[0053] To better understand the advantages of the lithium battery aluminum shell inner surface insulation treatment scheme proposed in this utility model, an analysis can be conducted through comparative embodiments and specific implementation methods:

[0054] Example 1: This example provides a battery casing, which is prepared in the following manner:

[0055] Step 1: Mix methyl vinyl silica gel and boron nitride at a mass ratio of 20%:80% to obtain a uniformly dispersed thermally conductive silica gel with a viscosity of 6500 mPa·s;

[0056] Step 2: Apply the thermally conductive silicone prepared in Step 1 to the inner surface of the aluminum shell using a spraying device. The spraying thickness is 40 μm, and the height of the blank area at the opening of the aluminum shell is 10 mm.

[0057] Step 3: The aluminum shell with thermally conductive silicone coating on the inner surface prepared in Step 2 is cured by heating at a temperature of 120°C.

[0058] The battery casing 100 has the following specifications: casing pressure resistance 1.55MPa, 0.25P discharge termination temperature 27.5℃, and temperature after 10 minutes of rest 27.1℃.

[0059] Example 2: The mass ratio of methyl vinyl silica gel to boron nitride was adjusted to 15%:85%, while other parameters remained the same as in Example 1. The battery casing 100 obtained had the following data: casing withstand voltage 1.49 MPa, 0.25P discharge termination temperature 27.3℃, and temperature after 10 minutes of rest 26.8℃.

[0060] Example 3: The coating thickness was adjusted to 80μm, and other parameters remained the same as in Example 1. The battery casing 100 was obtained with the following data: casing pressure resistance 1.82MPa, 0.25P discharge termination temperature 28℃, and temperature after 10min of rest 27.7℃.

[0061] Example 4: The heating temperature was adjusted to 150℃, and other parameters remained the same as in Example 1; the battery casing 100 was obtained with the following data: casing pressure resistance 1.52MPa, 0.25P discharge termination temperature 27.4℃, and temperature after 10 minutes of rest 27.1℃.

[0062] Comparative Example 1: The inner surface of the aluminum shell remains unchanged and is not insulated; the battery shell 100 data is as follows: shell withstand pressure 1.27MPa, 0.25P discharge termination temperature 27.1℃, temperature after 10min rest 26.6℃.

[0063] Comparative Example 2: Except for the opening at the adhesive coating area 121, the wall thickness is reduced by 50µm, and thermally conductive silicone is applied to the thinned area. The thermally conductive silicone layer is 50µm thick. Everything else remains the same as in Example 1. The battery casing 100 data is as follows: casing withstand voltage 1.46MPa, 0.25P discharge termination temperature 27.2℃, and temperature after 10 minutes of rest 26.6℃.

[0064] Comparative Example 3: The aluminum shell substrate was thinned to half the thickness of the shell body in Example 1. After applying adhesive, an inner shell 30 was pressed onto the inner surface of the thermally conductive silicone. The inner shell 30 had the same thickness as the shell body, and other aspects remained the same as in Example 1. The battery shell 100 data are as follows: shell pressure resistance 1.61MPa, 0.25P discharge termination temperature 27.3℃, and temperature after 10 minutes of rest 26.9℃.

[0065] Comparative Example 4: The thermally conductive silicone material was replaced with PET plastic, and everything else remained the same as in Example 1; the data for the tank shell 100 are as follows: shell pressure resistance 1.31MPa, 0.25P discharge termination temperature 28.6℃, and temperature after 10 minutes of rest 28.2℃.

[0066] Table 1. Data from this embodiment and the comparative example.

[0067] Example 1 1.55 27.5 27.1 Example 2 1.49 27.3 26.8 Example 3 1.82 28.0 27.7 Example 4 1.52 27.4 27.1 Comparative Example 1 1.27 27.1 26.6 Comparative Example 2 1.46 27.2 26.6 Comparative Example 3 1.61 27.3 26.9 Comparative Example 4 1.31 28.6 28.2

[0068] By comparing the data from the embodiments and the comparative examples, it can be seen that the aluminum shell in this embodiment generally has a higher pressure resistance than that in the comparative example, indicating that a reasonable insulating coating design helps to improve the overall mechanical properties of the shell. In particular, Embodiment 3 further improved the shell pressure resistance to 1.82 MPa by increasing the coating thickness. Furthermore, the cell discharge termination temperature and the temperature change after storage in this embodiment are relatively stable, indicating that the thermally conductive silicone layer can effectively conduct heat and prevent overheating inside the battery. In contrast, when PET plastic was used as the insulating layer in Comparative Example 4, the cell temperature increased significantly, indicating that its thermal conductivity is far inferior to that of thermally conductive silicone.

[0069] In summary, this embodiment achieves an optimized balance between shell pressure resistance and thermal management performance by adjusting parameters such as coating thickness and heating temperature, and it is highly compatible with existing production processes. In contrast, the design scheme in the comparative example has problems such as insufficient shell pressure resistance or poor thermal management performance, making it difficult to meet the needs of practical applications.

[0070] The present invention provides a battery casing that creatively solves the core contradiction in the prior art of balancing insulation protection and thermal management by setting a thermally conductive silicone layer on the inner surface of the aluminum casing. While ensuring electrochemical safety, it significantly improves the battery's heat dissipation performance, structural strength and manufacturing compatibility.

[0071] This invention effectively blocks the electrochemical corrosion path, improving battery safety and cycle life. Specifically, by covering the bottom and lower side walls of the casing with a thermally conductive silicone layer made of highly insulating organic silicone material, a reliable electronic barrier is formed, fundamentally preventing abnormal conduction between the aluminum casing and the negative electrode caused by production impurities, burrs, or assembly deviations, and significantly reducing safety risks such as leakage and thermal runaway caused by corrosion.

[0072] This invention enables efficient heat conduction and optimizes battery thermal management performance. Specifically, it employs a thermally conductive silicone layer composed of a high thermal conductivity filler and an organic silicone matrix. Its thermal conductivity is much higher than that of traditional PET / PP films or multi-layer organic coatings. This design significantly reduces the thermal resistance between the cell and the casing, promotes rapid heat transfer from the inside to the casing, and improves overall heat dissipation efficiency.

[0073] The partitioned coating design of this utility model takes into account both insulation protection and welding process compatibility. By setting a coated area and an uncoated area on the side wall, this design ensures that the laser welding area of ​​the top cover is an exposed metal surface, avoiding carbonization, blistering or gas release of the silicone material during high-temperature welding, thereby ensuring weld quality, airtightness and connection strength, and completely solving the process problem of traditional coatings interfering with welding.

[0074] This invention ensures insulation and thermal conductivity by thinning part of the shell and coating it with a thermally conductive silicone layer, while also improving energy density and space utilization. The thinning design minimizes the occupation of internal battery space, which is beneficial for improving electrode material filling rate and volumetric energy density.

[0075] This invention enhances mechanical strength and improves overall reliability through a multi-layered composite structure. The design of the inner shell structure forms a three-layer composite system: outer shell – thermally conductive silicone layer – inner shell. This design not only protects the thermally conductive silicone layer from mechanical damage to the electrode components but also significantly improves the shell's resistance to pressure, bending, and fatigue through the coordinated load-bearing capacity of the inner and outer shells.

[0076] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A battery casing, characterized in that, include: A housing body having an opening, the housing body including a bottom wall and side walls surrounding the bottom wall; A thermally conductive silicone layer, comprising a first thermally conductive silicone layer and a second thermally conductive silicone layer, wherein the first thermally conductive silicone layer covers the inner surface of the bottom wall, and the second thermally conductive silicone layer covers at least a portion of the inner surface of the side wall, and the edge of the second thermally conductive silicone layer near the bottom wall is connected to the edge of the first thermally conductive silicone layer.

2. The battery casing according to claim 1, characterized in that, The thermally conductive silicone layer is made of an organosilicon matrix and a thermally conductive filler. The organosilicon matrix includes one of vinyl silicone oil, methyl silicone oil, methyl vinyl silicone rubber, methyl phenyl silicone resin, and fluorosiloxane. The thermally conductive filler includes one of boron nitride, aluminum nitride, aluminum oxide, zinc oxide, and magnesium oxide.

3. The battery casing according to claim 1, characterized in that, The thickness of the thermally conductive silicone layer is t, where 5μm≤t≤500μm.

4. The battery casing according to claim 1, characterized in that, Along the direction from the opening to the bottom wall, the sidewall sequentially includes an uncoated area and a coated area, wherein the uncoated area is not covered by the second thermally conductive silicone layer, and the coated area is covered by the second thermally conductive silicone layer.

5. The battery casing according to claim 4, characterized in that, When the battery is placed upright, the lowest point of the uncoated area is higher than the liquid level of the electrolyte in the battery.

6. The battery casing according to claim 4, characterized in that, The height of the uncoated area is H, where 1mm ≤ H ≤ 100mm.

7. The battery casing according to claim 4, characterized in that, The inner surface of the coated area is thinned outward relative to the inner surface of the uncoated area to form a groove, and the thickness of the second thermally conductive silicone layer is greater than or equal to the depth of the groove.

8. The battery casing according to claim 4, characterized in that, It also includes an inner housing that covers the side of the thermally conductive silicone layer facing away from the housing body.

9. The battery casing according to claim 8, characterized in that, The wall thickness of the shell body accounts for 20% to 80% of the total wall thickness of the shell body and the inner shell.

10. The battery casing according to claim 1, characterized in that, The viscosity of the thermally conductive silicone layer before heating and curing is 100 mPa·s to 30000 mPa·s.

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