Battery heat dissipation device

Abstract

This application relates to a battery heat dissipation device, belonging to the field of device heat dissipation technology. The battery heat dissipation device includes a battery body and a battery cover layer. A solid cooling medium is disposed inside the battery body. The battery cover layer surrounds the battery body, and its inner wall surface is attached to the outer surface of the battery body. The battery cover layer has flow channels for accommodating the fluid cooling medium. Cooling of the battery body is achieved through heat transfer between the fluid cooling medium, the battery cover layer, the solid cooling medium, and the battery body. The battery heat dissipation device provided in this application achieves full-dimensional heat dissipation coverage from the internal core to the external surface of the battery, solving the defects of insufficient heat exchange efficiency and uneven temperature distribution in existing technologies.

Description

Technical Field

[0001] This application belongs to the field of device heat dissipation technology and relates to a battery heat dissipation device. Background Technology

[0002] As electrochemical devices such as fuel cells and high-power-density battery packs develop towards higher power density and integration, the large amount of heat generated during their operation has become a key bottleneck restricting performance, lifespan, and safety. Efficient, uniform, and reliable heat dissipation technology is a prerequisite for the large-scale commercial application of these devices.

[0003] Currently, mainstream battery cooling solutions mainly include air cooling, liquid cooling, and immersion cooling. Air cooling has a simple structure but a low heat transfer coefficient, making it only suitable for low heat load scenarios. Traditional liquid cooling technology uses fluid circulation within a flow channel for heat exchange, achieving better heat dissipation efficiency than air cooling. However, the flow channel design is complex, fluid leakage is common, and it is difficult to penetrate into narrow spaces such as cell gaps, leading to localized overheating of the cells. Standard full immersion solutions require the entire battery body and its connectors to be immersed in the cooling medium. This not only results in a large volume and high cost of the required cooling medium but also places extremely high demands on the sealing and insulation protection of non-heat-dissipating parts such as battery electrode connectors and sensors, increasing system complexity and the risk of failure.

[0004] Therefore, there is an urgent need for an innovative immersion cooling solution, to develop a new type of cooling medium that combines high insulation and high heat transfer properties, and to achieve precise and efficient utilization of the cooling medium through innovative system design, thereby comprehensively solving the problem that it is difficult to optimize heat dissipation efficiency, safety and economy in the existing technology. Summary of the Invention

[0005] This application provides a battery heat dissipation device that achieves full-dimensional heat dissipation coverage from the internal core to the external surface of the battery, solving the defects of insufficient heat exchange efficiency, uneven temperature distribution, and complex system structure in the prior art.

[0006] In some embodiments, the battery heat dissipation device provided in this application includes a battery body and a battery cover layer; a solid cooling medium is disposed inside the battery body; the battery cover layer is disposed around the battery body, and the inner wall surface of the battery cover layer is attached to the outer surface of the battery body; the battery cover layer is provided with a flow channel for containing a fluid cooling medium; the battery body is cooled by heat transfer between the fluid cooling medium, the battery cover layer, the solid cooling medium and the battery body.

[0007] In some embodiments, the battery pack layer further includes an outer wall surface, the flow channel includes an inner flow channel and an outer flow channel, the inner flow channel is disposed between the inner wall surface and the outer wall surface of the battery pack layer, and the outer flow channel is disposed outside the outer wall surface of the battery pack layer; the fluid cooling medium includes an inner fluid cooling medium and an outer fluid cooling medium; the inner flow channel is used to contain the inner fluid cooling medium, and the outer flow channel is used to contain the outer fluid cooling medium.

[0008] In some embodiments, the battery body is composed of multiple battery cells, and the solid cooling medium fills the gaps between the battery cells inside the battery body and is in thermal contact with the surface of the battery cells; the inner fluid cooling medium forms a convective heat transfer surface with the inner wall and outer wall of the battery cover layer, respectively, and the outer fluid cooling medium forms a convective heat transfer surface with the outer wall of the battery cover layer; the heat generated by the battery cells is sequentially transferred through the solid cooling medium, the battery cover layer, the inner fluid cooling medium and the outer fluid cooling medium and then discharged outward.

[0009] In some embodiments, the internal flow channel is a network of micro-flow channels composed of multiple regularly arranged micro-flow channels, which extend along the axial direction of the battery body, and the micro-flow channel network constitutes a directional path for the delivery of the internal fluid cooling medium.

[0010] In some embodiments, the outer wall surface of the battery cover layer is provided with a plurality of recessed structures or protruding structures. The recessed structures are formed by the outer wall surface of the battery cover layer being recessed inward along the radial direction of the battery body, and the protruding structures are formed by the outer wall surface of the battery cover layer being protruded outward along the radial direction of the battery body.

[0011] In some embodiments, the external fluid cooling medium includes supercritical carbon dioxide and a high-insulation-strength gas, wherein the high-insulation-strength gas includes at least one of trifluoroiodomethane, sulfur hexafluoride, and perfluoroketone.

[0012] In some embodiments, the volume ratio of the supercritical carbon dioxide to the high-insulation-strength gas is 1:0.01-0.05.

[0013] In some embodiments, the internal fluid cooling medium includes an insulating antioxidant, which includes alkylated diphenylamine, and the insulating antioxidant accounts for 0.05% to 1.0% of the mass percentage of the internal fluid cooling medium.

[0014] In some embodiments, the internal fluid cooling medium further includes a metal corrosion inhibitor, which includes benzotriazole, and the metal corrosion inhibitor accounts for 0.01% to 0.05% by mass in the internal fluid cooling medium.

[0015] In some embodiments, the internal fluid cooling medium further includes a fluorinated liquid, which includes one or a combination of two of perfluoro-4-methyl-2-pentene and 1,1,1,3,3-pentafluoropropane.

[0016] The battery heat dissipation device provided in this application has at least the following beneficial effects:

[0017] 1. Construct a three-level gradient synergistic heat dissipation system of solid-liquid-gas, combined with a micro-flow channel network and an external wall surface enhanced heat transfer structure, which effectively destroys the heat transfer boundary layer, reduces heat transfer thermal resistance, and significantly improves convective heat transfer efficiency. At the same time, it achieves uniform temperature control across the entire battery domain, smooths temperature peaks, eliminates local overheating, and extends the battery cycle life.

[0018] 2. It adopts a dual cooling medium design with independent internal and external flow channels and physical isolation, combined with a high-insulation composite external cooling medium, an insulating material coating layer, and supporting insulation protection and leakage detection structure. It simultaneously meets the dual requirements of high heat exchange efficiency and high electrical insulation, greatly reducing the difficulty of insulation design and improving the electrical safety of the device operation.

[0019] 3. The non-integral immersion encapsulation structure significantly reduces the amount of cooling medium used, lowers system costs, and reduces the difficulty of sealing and protecting non-heat-dissipating parts; the antioxidant and anti-corrosion components added to the internal cooling medium can effectively extend the service life of the medium, protect the integrity of the heat exchange structure, and improve the long-term reliability of the device.

[0020] 4. Adopting a multi-form composite cooling medium design, it can flexibly switch between air and liquid cooling modes according to the real-time heat load of the battery, adapting to the heat dissipation requirements of all working conditions from low-load standby to high-power full-load operation, improving the flexibility of heat dissipation control and the adaptability of scenarios.

[0021] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of this application more apparent, specific embodiments of this application are given below. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the structure of the battery pack layer in this application; Figure 2This is a schematic diagram of the structure of the battery pack after the insulating protective ring is installed.

[0024] In the attached diagram: 1. Inner wall surface; 2. Outer wall surface; 3. Inner flow channel; 4. Recessed / protruding structure; 5. Insulating protective ring; 6. Medium inlet and outlet. Detailed Implementation

[0025] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0026] The prefixes such as "first" and "second" used in this application embodiment are merely for distinguishing different descriptive objects and do not limit the position, order, priority, quantity, or content of the described objects. The use of ordinal numbers and other prefixes used to distinguish descriptive objects in this application embodiment does not constitute a limitation on the described objects. The description of the described objects is given in the claims or the context of the embodiments, and should not constitute unnecessary restrictions due to the use of such prefixes. Furthermore, in the description of this embodiment, unless otherwise stated, "multiple" means two or more.

[0027] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. In the description of the embodiments of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B; the term "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone.

[0028] In the embodiments provided in this application, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0029] As electrochemical devices such as fuel cells and high-power-density battery packs develop towards higher power density and integration, the large amount of heat generated during their operation has become a key bottleneck restricting performance, lifespan, and safety. Efficient, uniform, and reliable heat dissipation technology is a prerequisite for the large-scale commercial application of these devices.

[0030] Currently, mainstream battery cooling solutions mainly include air cooling, liquid cooling, and immersion cooling. Air cooling has a simple structure but a low heat transfer coefficient, making it only suitable for low heat load scenarios. While liquid cooling improves heat dissipation capacity, it suffers from multiple thermal resistance layers, uneven temperature distribution, and a complex and bulky system. In contrast, immersion cooling directly submerges the battery in an insulating coolant, achieving maximum contact area between the heat source and the cooling medium. This demonstrates significant advantages in heat dissipation uniformity and efficiency, and represents a cutting-edge research direction for high-power battery cooling.

[0031] However, existing immersion cooling technologies still suffer from several inherent defects that have not been adequately addressed, hindering their widespread application. Traditional immersion cooling relies heavily on the natural convection of the cooling medium or pump-driven overall flow, passively limiting its heat transfer efficiency to the medium's physical properties and flow regime. Especially under forced convection conditions, the cooling medium flowing over a smooth battery surface tends to form a thick laminar boundary layer, which constitutes the main thermal resistance. Current technologies lack proactive intervention and optimized design of the flow structure at the solid-liquid interface, failing to effectively disrupt the boundary layer to induce turbulence, thus limiting further improvements in the heat transfer coefficient. An ideal immersion cooling medium must simultaneously possess high insulation strength to ensure electrical safety, as well as high thermal conductivity and high heat capacity to improve heat transfer efficiency. Commonly used media such as mineral oil, silicone oil, and fluorinated liquids, while having good insulation properties, generally have low thermal conductivity, becoming a bottleneck for heat dissipation. On the other hand, some fluids with excellent heat transfer characteristics (such as supercritical carbon dioxide) have insufficient insulation properties. Existing technologies typically employ compromises or single-performance media, making it difficult to simultaneously meet the stringent requirements of efficient heat dissipation and absolute electrical safety within the extremely compact space of a battery.

[0032] Standard immersion solutions require the entire battery and its connectors to be submerged in the cooling medium. This not only results in a large volume and high cost of the required cooling medium (especially for special high-performance fluorinated liquids), but also places extremely high demands on the sealing and insulation of non-heat-dissipating components such as battery electrode joints and sensors, increasing system complexity and failure risk. The key to reducing system cost and improving reliability lies in precisely concentrating cooling resources on core heat-generating areas, reducing the amount of cooling medium used, and simplifying the sealing structure.

[0033] Therefore, to address the shortcomings of existing technologies, this embodiment proposes a battery heat dissipation device. This device is suitable for high-power-density batteries and battery heat dissipation and temperature control scenarios. Through a structural design of solid-fluid multi-medium synergistic heat exchange, it solves the pain points of insufficient heat exchange efficiency, uneven temperature distribution, and complex system structure of existing battery heat dissipation solutions.

[0034] In some embodiments, the battery heat dissipation device includes a battery body and a battery cover layer. A solid cooling medium is disposed inside the battery body; the battery cover layer is disposed around the battery body, and the inner wall surface 1 of the battery cover layer is attached to the outer surface of the battery body; the battery cover layer is provided with a flow channel for containing a fluid cooling medium; the battery body is cooled by heat transfer between the fluid cooling medium, the battery cover layer, the solid cooling medium and the battery body.

[0035] Optionally, the battery body is a columnar structure formed by multiple cells connected in series or in parallel, which can be adapted to battery products with different power and size specifications.

[0036] The technical advantages of the above structure are: to achieve full-dimensional heat dissipation coverage of the battery from the internal core to the external surface, which not only quickly suppresses the internal temperature peaks of the battery and eliminates local temperature differences between cells through solid cooling medium, but also enables the continuous outward dissipation of heat through fluid cooling medium, taking into account both the transient response capability and steady-state heat exchange efficiency; at the same time, it does not require the entire battery to be immersed in the cooling medium, which greatly reduces the amount of cooling medium used, reduces system cost and the difficulty of sealing and protecting non-heat dissipation parts.

[0037] like Figure 1 As shown, in some embodiments, the battery pack layer further includes an outer wall surface 2, and the flow channels include an inner flow channel 3 and an outer flow channel. The inner flow channel 3 is disposed between the inner wall surface 1 and the outer wall surface 2 of the battery pack layer, and the outer flow channel is disposed outside the outer wall surface 2 of the battery pack layer. The fluid cooling medium includes an inner fluid cooling medium and an outer fluid cooling medium. The inner flow channel 3 is used to contain the inner fluid cooling medium, and the outer flow channel is used to contain the outer fluid cooling medium. The inner fluid cooling medium forms a convective heat transfer surface with the inner wall surface 1 and the outer wall surface 2 of the battery pack layer, respectively, and the outer fluid cooling medium forms a convective heat transfer surface with the outer wall surface 2 of the battery pack layer.

[0038] The heat dissipation coating is an integrated closed structure adapted to the shape of the battery body. It can be designed into a cylindrical, cuboid or other shapes according to the shape and size of the battery body. The shape of the inner wall 1 is completely matched with the shape of the outer surface of the battery body. The thickness difference between the inner wall 1 and the outer wall 2 is 3-30mm. The inner wall 1 and the flow channel are both made of epoxy resin board with good insulation and high strength. The inner flow channel 3 is a closed interlayer space formed between the inner wall 1 and the outer wall 2. The inner fluid cooling medium and the outer fluid cooling medium are two independent media that are physically not connected.

[0039] The above technical solution, through the design of dual independent internal and external flow channels, constructs a two-stage independent fluid heat exchange system. It can flexibly match the operating parameters of the two fluid cooling media according to the real-time heat load of the battery, and can even switch between gas and liquid cooling media according to the cooling demand. In the initial low-load stage, gas cooling media is used for cooling, and liquid cooling media is switched when the cooling demand is large. At the same time, the internal and external cooling media are physically isolated from each other. Combined with the insulation material coating structure, the insulation design difficulty of the device is greatly reduced, and the safety and stability of operation are improved.

[0040] In some embodiments, the heat generated by the battery body is first absorbed by the solid cooling medium. The unabsorbed heat is conducted to the battery cover layer through the outer surface of the battery body. Then, the heat of the battery cover layer is absorbed and carried away by the inner fluid cooling medium flowing in the inner channel 3 and the outer fluid cooling medium flowing in the outer channel.

[0041] The battery body comprises multiple cells, with a solid cooling medium filling the gaps between the cells and between the outer surface of the battery body and the cells, and in thermal contact with the cell surfaces. The thickness of the solid cooling medium is 5-10mm. During the charging and discharging process of the battery body, the heat generated is first absorbed by the solid cooling medium through thermal conduction, utilizing the latent heat of phase change to achieve rapid heat storage and buffering. The heat not absorbed by the solid cooling medium is directly conducted through the outer surface of the battery body to the inner wall 1 of the precisely fitted battery pack, and then undergoes forced convection heat exchange between the inner wall 1 and the inner fluid cooling medium in the inner flow channel 3. The directional flow of the inner fluid cooling medium continuously carries the heat out of the sealed interlayer. The heat carried by the inner fluid cooling medium is simultaneously conducted through the outer wall 2 of the battery pack to the outer fluid cooling medium in the outer flow channel, and the heat is finally dissipated outward through the convection heat exchange of the outer fluid cooling medium.

[0042] Through the above technical solution, a three-level gradient heat dissipation link is formed: "solid medium heat storage buffer - internal fluid medium secondary heat exchange - external fluid medium final dissipation". This realizes the efficient transfer of battery heat step by step, which not only avoids the problem of local overheating of the battery, but also ensures that the heat is continuously and stably dissipated to the outside, greatly improving the uniformity of the overall temperature distribution of the battery and extending the battery cycle life.

[0043] In some embodiments, the inner flow channel 3 is a network of micro-flow channels composed of multiple regularly arranged micro-flow channels. The micro-flow channels extend along the axial direction of the battery body, and the micro-flow channel network constitutes a directional path for the delivery of the internal fluid cooling medium.

[0044] Among them, the micro-channel network can be designed as an array of honeycomb, rectangle and square, forming a complete transport path for the fluid from the inlet to the outlet, avoiding the formation of flow dead zones in the cooling medium in the channel, and realizing full contact between the cooling medium and the heat exchange interface.

[0045] By planning a fixed directional flow path for the internal fluid cooling medium through a micro-channel network, the cooling medium can fully cover the outer surface of the battery body, eliminating heat dissipation blind spots. At the same time, it can constrain the flow state of the internal fluid cooling medium, increase the medium velocity and turbulence, effectively destroy the laminar boundary layer of the solid-liquid interface, reduce the heat transfer resistance, significantly improve the heat transfer coefficient of the internal fluid cooling medium, and further ensure uniform heat dissipation in all areas of the battery body.

[0046] In some embodiments, the outer wall surface 2 of the battery cover layer is provided with a plurality of recessed structures 4 or protruding structures 4. The recessed structure 4 is formed by the outer wall surface 2 of the battery cover layer being recessed inward along the radial direction of the battery body, and the protruding structure 4 is formed by the outer wall surface 2 of the battery cover layer being protruded outward along the radial direction of the battery body.

[0047] Among them, the recessed structure 4 can be uniformly distributed hemispherical recesses, with the distance between the centers of adjacent recesses being 1.5-3 times the recess radius, the recess depth being 1 / 20-1 / 10 of the thickness of the outer wall 2, and the number of recesses being 4-10 per square centimeter, thereby maximizing the heat exchange area and ensuring the uniformity of flow disturbance.

[0048] The recessed or protruding structure 4 on the outer wall surface 2 significantly increases the heat exchange area between the outer wall surface 2 and the external fluid cooling medium. At the same time, it can effectively disturb the flow state of the external fluid cooling medium, destroy the laminar boundary layer at the outer wall surface 2, enhance the convective heat transfer effect between the outer wall surface 2 and the external fluid cooling medium, and further improve the overall heat dissipation capacity of the device.

[0049] like Figure 2 As shown, in some embodiments, insulating protective rings 5 ​​are provided at both ends of the battery pack layer to further improve the insulation protection performance of the electrode parts. The insulating protective rings 5 ​​cover both ends of the inner flow channel 3, making the inner flow channel 3 a closed space.

[0050] In some embodiments, the insulating protective ring 5 is provided with a medium inlet / outlet 6 for the internal fluid cooling medium to enter and exit the battery pack layer, and at least two medium inlets / outlets 6 are symmetrically arranged around the central axis of the battery body.

[0051] In some embodiments, the outer wall surface 2 of the battery pack layer can also be connected to a current sensor to detect leakage current in the device and improve the safety protection capability of the device operation.

[0052] The accompanying insulation protection and leakage detection structure can enhance heat dissipation while ensuring the electrical safety of the device in all aspects.

[0053] In some embodiments, the external fluid medium serves as an important carrier for heat dissipation of the battery cell. It employs a mixed system of supercritical carbon dioxide and a gas with high insulation strength, enabling the external fluid medium to possess both excellent heat dissipation performance and electrical safety.

[0054] Specifically, the selection of high-insulation-strength gases includes trifluoroiodomethane (CF3I), sulfur hexafluoride (SF6), and perfluoroketone (C6F). 12 The gas can be one of the following: O, or a combination of two or more of the above three gases. These gases all possess extremely high insulation breakdown strength, which can effectively avoid safety hazards caused by dielectric conductivity during the operation of the battery cell. At the same time, they have strong chemical stability and will not react with the battery cell material.

[0055] In some embodiments, to balance heat dissipation efficiency and insulation performance, the volume ratio of supercritical carbon dioxide to high-insulation-strength gas is limited to 1:0.01 to 1:0.05. This ratio range is determined based on experimental verification: when the volume percentage of high-insulation-strength gas is less than 0.01, the insulation performance of the mixed medium cannot meet the high-voltage operating requirements of the battery cell, easily leading to partial discharge; when the percentage is greater than 0.05, it significantly reduces the fluidity and heat transfer coefficient of supercritical carbon dioxide, resulting in decreased heat dissipation efficiency. The 1:0.01-0.05 ratio range ensures that the mixed medium possesses excellent heat transfer characteristics close to those of supercritical carbon dioxide, while the synergistic effect of the high-insulation-strength gas ensures that the insulation strength of the medium reaches the safety standard corresponding to the battery cell's operating voltage, achieving dual protection of heat dissipation and insulation.

[0056] In some embodiments, the internal fluid cooling medium serves as the core heat dissipation carrier in scenarios with high cooling demand. It comprises insulating antioxidants, metal corrosion inhibitors, and fluoride liquids. The selection and proportioning of each component are based on heat dissipation efficiency, service life, and equipment compatibility. The insulating antioxidant added to the internal fluid cooling medium is specifically alkylated diphenylamine, which accounts for 0.05% to 1.0% of the total mass of the internal fluid cooling medium. Alkylated diphenylamine not only possesses excellent insulating properties, preventing interference from the battery cell circuitry caused by the conductivity of the cooling medium, but also slows down the aging and deterioration of the cooling medium by capturing free radicals in the medium and inhibiting oxidation chain reactions. Experimental data shows that alkylated diphenylamine within this ratio range can effectively reduce the oxidation rate of the medium under high-temperature conditions, extending the service life of the cooling medium, while ensuring that excessive addition does not increase the viscosity of the medium, thus maintaining its flow and heat dissipation performance.

[0057] To protect the internal metal components of the battery from corrosion by the cooling medium, a metal corrosion inhibitor—benzotriazole—is added to the internal fluid cooling medium at a mass percentage of 0.01% to 0.05%. Benzotriazole forms a dense chelate protective film with the active sites on the metal surface, blocking contact between the metal and trace amounts of moisture and oxygen in the cooling medium, thereby inhibiting electrochemical corrosion. This formulation balances corrosion inhibition effectiveness with cost-effectiveness: below 0.01%, a complete protective film cannot be formed, resulting in poor corrosion inhibition; above 0.05%, excess inhibitor may precipitate on the metal surface, clogging cooling channels and affecting medium flow; while the 0.01% to 0.05% range achieves a perfect balance between efficient corrosion inhibition and unobstructed channel flow.

[0058] The main component of the internal fluid cooling medium—that is, the remainder after deducting the insulating antioxidant and metal corrosion inhibitor—is a fluorinated liquid. Specifically, the fluorinated liquid is selected from any one of perfluoro-4-methyl-2-pentene and 1,1,1,3,3-pentafluoropropane, or a combination of two of them. This type of fluorinated liquid possesses unique thermodynamic properties, with a boiling point range of 45°C to 80°C under standard atmospheric pressure, which perfectly matches the normal operating temperature and abnormal heating temperature range of the battery cell. When the battery cell temperature rises to near the boiling point of the fluorinated liquid, the medium can absorb a large amount of heat through phase change, rapidly reducing the battery cell temperature. At the same time, it has strong chemical inertness and good compatibility with battery cell materials, cavity structural components, and other additives, and will not decompose or react to generate harmful substances. Furthermore, it has low viscosity and good fluidity, allowing it to circulate rapidly within the cooling channel, improving overall heat dissipation efficiency.

[0059] In some embodiments, the solid cooling medium serves as a key heat dissipation component in the battery heat dissipation device, fitting the gaps between battery cells. Cross-linked and modified polyethylene glycol is used as the core phase change material. Through precise molecular weight control and structural modification, efficient adsorption and slow release of localized high temperatures within the battery cell gaps are achieved. Specific design details and performance characteristics are as follows: The core reason for choosing polyethylene glycol (PEG) as the base material for the solid cooling medium is its excellent latent heat of phase change, chemical stability, and compatibility with battery cell materials. PEG itself is a non-toxic and odorless polymer compound that does not chemically react with battery electrode materials or cavity structural components. Furthermore, its volume change during phase change is gradual, preventing mechanical stress damage to the battery cell due to expansion or contraction.

[0060] To further optimize its phase change performance and structural stability, polyethylene glycol was cross-linked and modified: a three-dimensional network structure was constructed by introducing a cross-linking agent to improve the material's formability and high-temperature stability, and to avoid melting and loss at high temperatures; at the same time, the regularity of the molecular chain was adjusted by chemical modification to make the phase change process more stable and the latent heat release more persistent, adapting to the temperature fluctuation scenarios during the operation of the battery cell.

[0061] Using polyethylene glycol (PEG) as the base material as a solid cooling medium allows for precise matching of the battery cell's operating temperature range and heat dissipation requirements by adjusting the PEG's molecular weight. As the molecular weight increases, the PEG's melting temperature and crystallization temperature also increase with the number average molecular weight. When the molecular weight is between 4000 and 6000, the melting temperature is ≤70℃ and the crystallization temperature is ≤45℃.

[0062] The design of this parameter range is fully adapted to the working characteristics of the battery cell: the normal operating temperature of the battery cell is usually between 25-55℃, at which time the solid cooling medium remains solid and does not undergo phase change; when the temperature of the battery cell rises above 60℃ due to high load operation or local short circuit, the cooling medium initiates a melting phase change and absorbs some heat; when the temperature rises further to the dangerous threshold of above 70℃, the medium completely melts, absorbs a large amount of latent heat, and rapidly reduces the local temperature of the gap between the battery cells, preventing the battery cell from triggering thermal runaway due to overheating.

[0063] Meanwhile, polyethylene glycol of different molecular weights can be flexibly selected according to the specific heating power of the battery cell: for example, high-power battery cells can use polyethylene glycol with a molecular weight of about 4000-6000, which has a latent heat of molten metal of up to 68.7kJ / kg and a larger heat absorption capacity.

[0064] The solid cooling medium is installed using a "gap-filling" method, directly placed within the cell gaps inside the battery body cavity, closely adhering to the battery surface for extremely close-range heat exchange. Its heat dissipation process consists of two stages: the first stage is the melting initiation stage, where the solid cooling medium begins to melt when the cell temperature rises above 55°C, absorbing heat through molecular restructuring and slowing the rate of temperature increase; the second stage is the complete melting stage, where the solid cooling medium completely transforms from a solid to a liquid state when the temperature further rises above 60°C. During this process, it absorbs a large amount of latent heat, rapidly carrying away heat from the cell surface and keeping the cell temperature within a safe range. When the battery load decreases and the temperature drops, the liquid cooling medium recrystallizes back into a solid state, releasing latent heat and completing the heat dissipation cycle, thus achieving dynamic regulation of the cell temperature.

[0065] The solid-liquid phase change cycle characteristic of the solid cooling medium in this technical solution enables it to achieve passive and efficient heat dissipation without additional power, complementing the gaseous and liquid cooling media to jointly construct a comprehensive and multi-layered battery heat dissipation system.

[0066] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be covered. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A battery heat dissipation device, characterized in that, include: The battery body contains a solid cooling medium. A battery cover layer is disposed around the battery body, and the inner wall surface of the battery cover layer is attached to the outer surface of the battery body; the battery cover layer is provided with a flow channel for containing a fluid cooling medium; The cooling of the battery body is achieved through heat transfer between the fluid cooling medium, the battery cover layer, the solid cooling medium and the battery body.

2. The battery heat dissipation device according to claim 1, characterized in that, The battery pack layer also includes an outer wall surface, and the flow channel includes an inner flow channel and an outer flow channel. The inner flow channel is disposed between the inner wall surface and the outer wall surface of the battery pack layer, and the outer flow channel is disposed outside the outer wall surface of the battery pack layer. The fluid cooling medium includes an inner fluid cooling medium and an outer fluid cooling medium; the inner flow channel is used to contain the inner fluid cooling medium, and the outer flow channel is used to contain the outer fluid cooling medium.

3. The battery heat dissipation device according to claim 2, characterized in that, The battery body is composed of multiple cells, and the solid cooling medium fills the gaps between the cells inside the battery body and is in thermal contact with the surface of the cells. The internal fluid cooling medium forms convective heat transfer surfaces with the inner and outer walls of the battery pack layer, respectively, and the external fluid cooling medium forms a convective heat transfer surface with the outer wall of the battery pack layer. The heat generated by the battery cell is sequentially transferred through the solid cooling medium, the battery pack layer, the inner fluid cooling medium, and the outer fluid cooling medium, and then discharged outwards.

4. The battery heat dissipation device according to claim 2, characterized in that, The internal flow channel is a network of micro-flow channels arranged in a regular pattern. The micro-flow channels extend along the axial direction of the battery body, and the micro-flow channel network forms a directional path for the internal fluid cooling medium transport.

5. The battery heat dissipation device according to claim 2, characterized in that, The outer wall surface of the battery cover layer is provided with multiple recessed or protruding structures. The recessed structure is formed by the outer wall surface of the battery cover layer being recessed inward along the radial direction of the battery body, and the protruding structure is formed by the outer wall surface of the battery cover layer being protruded outward along the radial direction of the battery body.

6. The battery heat dissipation device according to any one of claims 2-5, characterized in that, The external fluid cooling medium includes supercritical carbon dioxide and a high-insulation-strength gas, wherein the high-insulation-strength gas includes at least one of trifluoroiodomethane, sulfur hexafluoride, and perfluoroketone.

7. The battery heat dissipation device according to claim 6, characterized in that, The volume ratio of supercritical carbon dioxide to high-insulation-strength gas is 1:0.01-0.

05.

8. The battery heat dissipation device according to any one of claims 2-5, characterized in that, The internal fluid cooling medium includes an insulating antioxidant, which includes alkylated diphenylamine, and the insulating antioxidant accounts for 0.05% to 1.0% of the mass percentage of the internal fluid cooling medium.

9. The battery heat dissipation device according to claim 8, characterized in that, The internal fluid cooling medium also includes a metal corrosion inhibitor, which includes benzotriazole, and the metal corrosion inhibitor accounts for 0.01% to 0.05% of the mass percentage of the internal fluid cooling medium.

10. The battery heat dissipation device according to claim 9, characterized in that, The internal fluid cooling medium also includes a fluorinated liquid, which includes one or a combination of two of perfluoro-4-methyl-2-pentene and 1,1,1,3,3-pentafluoropropane.

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