A square case lithium ion battery with enhanced heat conduction and a battery pack

Abstract

The utility model provides a kind of square shell lithium ion battery and battery pack of enhanced heat conduction, it is related to lithium ion battery heat conduction technical field, comprising: shell top cover and positive and negative pole connecting piece;First heat conduction plate is equipped between the shell top cover and the positive and negative pole connecting piece, the first heat conduction plate at least covers the welding area between the positive and negative pole connecting piece with positive and negative pole lug. Advantageous effect is by setting first heat conduction plate between shell top cover and positive and negative pole connecting piece, heat generated by positive and negative pole connecting piece can be conducted to battery shell, heat conduction is strengthened to dissipate heat to external air environment, heat dissipation efficiency can be improved by 10%, lithium ion battery 1C discharge temperature can reach the effect of reducing 5 ℃.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion battery thermal conductivity technology, and in particular to a square-shell lithium-ion battery and battery pack with enhanced thermal conductivity. Background Technology

[0002] In today's trend towards green transportation and sustainable development, lithium-ion batteries, with their high energy density, long cycle life, and relative environmental friendliness, have achieved widespread and mature application in various transportation sectors, including urban buses, passenger cars, and logistics vehicles. Furthermore, with continuous technological advancements and increasingly stringent environmental requirements, the electrification transformation of the heavy-duty truck sector has gradually become a focus of industry attention and is gaining increasing popularity.

[0003] However, the performance requirements for lithium-ion batteries in the heavy-duty truck sector are far more stringent than those for other vehicles. Electric heavy-duty trucks typically require individual lithium-ion batteries to possess characteristics such as large size, high capacity, and high power to meet practical needs such as heavy loads, long range, and rapid charging and discharging. However, these high-performance specifications also present significant challenges to battery heat dissipation. High-capacity, thicker individual lithium-ion batteries generate significantly more heat during operation due to active internal chemical reactions. Simultaneously, the increased thickness lengthens the internal heat conduction path, resulting in slower heat transfer. These combined factors lead to a substantial increase in temperature rise during use compared to smaller, thinner batteries.

[0004] Specifically, the area above the welding point of the battery's internal electrode tabs is a weak point for heat dissipation. As a critical component for current transmission within the battery, the electrode tabs generate significant heat during charging and discharging. However, due to their location inside the battery and the relatively enclosed space above them, there is a lack of effective heat dissipation channels, making it difficult for heat to be quickly conducted to the battery casing and dissipated into the external environment. This leads to heat accumulation in this area, causing localized temperature increases and impacting the overall performance and safety of the battery. Prolonged exposure to high temperatures not only accelerates the aging of internal battery materials, reducing battery capacity and cycle life, but may also trigger serious safety incidents such as thermal runaway. Utility Model Content

[0005] To address the problems existing in the prior art, this utility model provides a square-shell lithium-ion battery with enhanced thermal conductivity, including a top cover and positive and negative electrode connecting pieces; a first heat-conducting plate is provided between the top cover and the positive and negative electrode connecting pieces, and the first heat-conducting plate at least covers the welding area between the positive and negative electrode connecting pieces and the positive and negative electrode tabs.

[0006] Preferably, the two sides of the first heat-conducting plate are in contact with the top cover of the housing and the positive and negative electrode connecting pieces, respectively.

[0007] Preferably, it also includes a second heat-conducting plate disposed on the inner wall of both sides of the narrow face of the housing.

[0008] Preferably, the first heat-conducting plate and the second heat-conducting plate are made of pad material.

[0009] Preferably, the pad material is a carbon fiber thermally conductive material or a thermally conductive phase change material.

[0010] Preferably, the housing contains a core, and a heat-conducting element is provided between the bottom of the core and the inner wall of the housing.

[0011] Preferably, the thermally conductive component is a thermally conductive silicone pad.

[0012] Preferably, the inner wall at the bottom of the housing is provided with a water-cooling pipe.

[0013] Preferably, the heat-conducting component and the water-cooling pipe are separated by an aluminum plate.

[0014] This utility model also provides a battery pack, including the above-mentioned prismatic lithium-ion battery.

[0015] The above technical solution has the following advantages or beneficial effects: by setting a first heat-conducting plate between the top cover of the casing and the positive and negative electrode connecting plates, the heat generated by the positive and negative electrode connecting plates can be conducted to the battery casing, and the heat conduction is enhanced to dissipate the heat to the external air environment. The heat dissipation efficiency can be improved by 10%, and the 1C discharge temperature of the lithium-ion battery can be reduced by 5°C. Attached Figure Description

[0016] Figure 1 This is a schematic diagram showing the placement of the first heat-conducting plate in a preferred embodiment of the present invention. Figure 2 This is a schematic diagram showing the arrangement of the second heat-conducting plate and the heat-conducting component in a preferred embodiment of the present invention. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The present invention is not limited to this embodiment; other embodiments that conform to the spirit of the present invention may also fall within its scope.

[0018] In a preferred embodiment of this utility model, based on the above-mentioned problems existing in the prior art, a square-shell lithium-ion battery with enhanced thermal conductivity is provided, such as... Figure 1 As shown, it includes a housing top cover 1 and positive and negative electrode connecting pieces 2; a first heat-conducting plate 3 is provided between the housing top cover 1 and the positive and negative electrode connecting pieces 2, and the first heat-conducting plate 3 at least covers the welding area between the positive and negative electrode connecting pieces 2 and the positive and negative electrode tabs.

[0019] Specifically, in this embodiment, the first heat-conducting plate 3 is disposed above the positive and negative electrode connecting piece 2 and below the top cover 1 of the casing. The two sides of the first heat-conducting plate 3 respectively contact the top cover 1 of the casing and the positive and negative electrode connecting piece 2, reducing thermal resistance. This allows the heat generated on the positive and negative electrode connecting piece 2 to be transferred more smoothly from the positive and negative electrode connecting piece 2 to the first heat-conducting plate 3, and then through the first heat-conducting plate 3 to the top cover 1 of the casing, and finally dissipated to the outside of the battery.

[0020] Furthermore, considering that the welding position of the internal electrode tabs in the battery will generate a lot of heat during the charging and discharging process, by setting the first heat-conducting plate 3 to at least cover the welding area between the positive and negative electrode tabs and the positive and negative electrode connecting pieces 2, the large amount of heat generated at the welding position can be directly transferred through the first heat-conducting plate 3, thereby reducing the working temperature of the battery cell.

[0021] Because the installation location of the first heat-conducting plate 3 is prone to heat accumulation during battery operation, and the space is relatively complex, it must possess a certain degree of rigidity to ensure that it can effectively perform its heat conduction function and be stably fixed above the welding position of the internal electrode connecting piece. The internal space of the battery is compact, and the layout of various components is precise and interconnected. When installing the first heat-conducting plate 3, it needs to be precisely placed above the welding position of the electrode connecting piece and tightly fitted with the surrounding battery structure. If the rigidity of the first heat-conducting plate 3 is insufficient, it is prone to deformation during installation. For example, when an operator attempts to place the first heat-conducting plate 3 in the designated position, it may bend or twist due to slight pressure or impact, resulting in inaccurate alignment with the welding position and potentially affecting the normal installation of other components.

[0022] The first heat-conducting plate 3, with its certain rigidity, maintains its shape and dimensional stability during installation. Operators can easily place it in the designated position and securely fix it inside the battery using simple fixing methods (such as clips, bolts, etc.). This stable installation not only improves installation efficiency but also reduces the risk of battery failure due to improper installation.

[0023] In addition, the battery structure above the welding position of the tab connection is relatively fragile. During the charging and discharging process, this area may be subjected to certain mechanical and thermal stresses due to the flow of current and the generation of heat. If this area lacks sufficient support, structural deformation and loosening may easily occur, thereby affecting the overall performance and safety of the battery. Therefore, the first heat-conducting plate 3 needs to provide both thermal conductivity and support.

[0024] In summary, the first heat-conducting plate 3 is preferably made of pad material, with a thickness of 0.9 mm and a thermal conductivity of 12 W / (m·K).

[0025] More preferably, the pad material should include at least the following two: The first option: The pad material can be carbon fiber thermal conductive material. The material composition is a carbon fiber thermal conductive sheet material obtained by filling an epoxy resin matrix with carbon fiber (C) and alumina (Al2O3) in a 1:1 ratio. The epoxy resin matrix, with its excellent adhesion and chemical stability, provides a stable supporting structure for the carbon fiber and alumina, ensuring their uniform dispersion. Carbon fiber, renowned for its high strength, high modulus, and excellent thermal conductivity, forms efficient heat conduction channels in composite materials, rapidly transferring heat away from the heat source. Alumina, also a material with good thermal conductivity, works in conjunction with carbon fiber to further enhance the thermal conductivity of the thermal conductive sheet. This 1:1 filling ratio has been carefully researched and experimentally verified, achieving a good balance between thermal conductivity, mechanical properties, and cost.

[0026] From a physical perspective, this carbon fiber thermal conductive material has a thickness range of 0.3~12mm. This wide thickness range allows it to adapt to the needs of different application scenarios. For example, in some electronic devices with stringent space requirements, a thinner 0.3mm thick thermal conductive sheet can be selected to save space; while in applications requiring higher pressure or stronger thermal conductivity, a thicker 12mm thermal conductive sheet can be selected to ensure sufficient thermal conductivity area and strength. Its density is 2.6±0.2g / cm³, a relatively moderate density that ensures thermal conductivity without adding excessive weight to the equipment. The applicable temperature range is -50~160℃, meaning it can operate normally in extremely cold and high-temperature environments. Whether in cold outdoor environments or high-temperature industrial production scenarios, it can stably perform its thermal conductivity function, providing a reliable thermal management solution for equipment.

[0027] The second type: The pad material can be a thermally conductive phase change material. The material composition consists of copper particles doped with boron nitride. Copper particles themselves have extremely high thermal conductivity, making them an excellent heat-conducting medium. In thermally conductive phase change materials, copper particles, as the primary heat-conducting phase, can rapidly absorb and transfer heat. Boron nitride, on the other hand, is a material with good thermal conductivity and insulation properties. Its addition not only further improves the material's thermal conductivity but also enhances its hardness and mechanical strength. Boron nitride acts as a filler and support within the copper particles, allowing the material to withstand certain pressure and deformation while maintaining good thermal conductivity, making it less prone to damage.

[0028] This thermally conductive phase change material exhibits phase change properties, undergoing a phase transition from solid to liquid at a certain temperature. During this transition, the material absorbs a significant amount of heat while maintaining a relatively stable temperature, effectively controlling the rise in equipment temperature. When the temperature decreases, the material reverts from liquid to solid, releasing the absorbed heat. This phase change process continuously regulates the equipment temperature, providing a stable thermal environment. Its inherent rigidity allows it to better maintain its shape and position during installation and use, preventing displacement or deformation and ensuring the stability and reliability of its thermal conductivity.

[0029] In practical applications, the appropriate pad material should be selected according to the specific usage scenario and requirements to achieve the best thermal conductivity and equipment thermal management.

[0030] Furthermore, due to the unavoidable gaps between the battery cell and the inner walls of the narrow sides of the casing in the actual structure and operation of prismatic batteries, these gaps are usually filled with air. Air is a poor conductor of heat, with a thermal conductivity far lower than that of common metals and thermally conductive materials. During battery charging and discharging, the battery cell generates a large amount of heat, which should be quickly conducted to the battery casing and dissipated into the external environment. However, due to the air gaps between the battery cell and the inner walls of the narrow sides of the casing, the heat conduction path is severely hindered. Heat accumulates near the battery cell and cannot be effectively dissipated in a timely manner, leading to a localized temperature increase, which in turn affects the overall performance and safety of the battery. Prolonged exposure to high temperatures will gradually reduce the battery's capacity, significantly shorten its cycle life, and may even trigger serious safety accidents such as battery thermal runaway.

[0031] Based on this, in a preferred embodiment of the present invention, such as Figure 2 As shown, it also includes a second heat-conducting plate 4, which is disposed on the inner wall of both sides of the narrow face of the shell.

[0032] Specifically, in this embodiment, by setting the second heat-conducting plate 4, the heat generated by the battery cell can be quickly absorbed from the side of the battery and conducted to the battery casing, accelerating the heat dissipation and improving the heat dissipation efficiency by 20%, thereby reducing the operating temperature of the battery.

[0033] Furthermore, since the second heat-conducting plate 4 is installed along the height of the battery, if its rigidity is insufficient, it will gradually deform and bend under the influence of the battery's own weight, the pressure during battery assembly, and the minor vibrations generated during battery operation, making it unable to tightly adhere to the cell and the narrow inner wall of the casing. This would disrupt the originally designed heat conduction channel, preventing heat from being conducted along the expected path and significantly reducing the heat dissipation effect. Therefore, in a preferred embodiment of this invention, the second heat-conducting plate 4 is also made of pad material, with a preferred thickness of 1.35 mm and a thermal conductivity of 12 W / (m·K), to efficiently conduct the heat generated by the core from both narrow faces to the casing, thereby dissipating the heat to the outside air environment.

[0034] As can be seen, the second heat-conducting plate 4 also needs to have a certain degree of hardness, so that while ensuring thermal conductivity, it has sufficient hardness to support its own weight and resist external pressure, thereby stably performing its heat dissipation function and providing strong protection for the safe and efficient operation of the prismatic battery. The specific material parameters of the pad material are the same as those of the first heat-conducting plate 4, and will not be repeated here.

[0035] Inside the prismatic battery, the winding core, as a core component, generates a significant amount of heat during charging and discharging. Due to the battery's internal structure and electrolyte distribution, heat tends to accumulate and is difficult to dissipate in the bottom area of ​​the winding core. Therefore, in a preferred embodiment of this invention, such as... Figure 2 As shown, a core is loaded inside the shell, and a heat-conducting element 5 is provided between the bottom of the core and the inner wall of the shell to enhance the heat conduction at the bottom.

[0036] Meanwhile, since there is electrolyte at the bottom of the winding core, and the electrolyte has a certain degree of chemical activity, it may corrode the materials in contact with it. This requires the bottom heat-conducting component to not only have good thermal conductivity to quickly conduct the heat generated by the winding core away, but also excellent corrosion resistance to ensure that it will not degrade or be damaged during long-term contact with the electrolyte, thereby ensuring the stable operation and safety of the battery. Based on this, in a preferred embodiment of this invention, the heat-conducting component 5 is a thermally conductive silicone pad, which can quickly transfer the heat from the bottom of the winding core to the inner wall of the bottom of the casing. Its soft texture can conform well to the uneven surfaces of the bottom of the winding core and the inner wall of the casing, filling the tiny gaps between them, reducing thermal resistance, and improving heat conduction efficiency. Moreover, the thermally conductive silicone pad has good flexibility and elasticity, and can automatically adjust its shape when the battery is subjected to vibration or temperature changes, maintaining close contact with the winding core and the casing, ensuring the stability of the heat dissipation effect. In addition, the thermally conductive silicone pad also has good insulation properties, which can effectively prevent safety hazards such as internal short circuits in the battery.

[0037] To further improve heat dissipation, in a preferred embodiment of this invention, a water-cooling pipe is provided on the inner wall of the bottom of the casing, and the forced convection heat dissipation coefficient of the water-cooling pipe is preferably 500 W / (m·K). When the battery is working, the heat generated by the winding core is quickly conducted to the inner wall of the bottom of the casing through the bottom thermally conductive silicone pad. At this time, the coolant in the water-cooling pipe begins to play its role. The coolant circulates within the water-cooling pipe, continuously absorbing the heat from the inner wall of the bottom of the casing and carrying it away. This forced convection method can quickly reduce the battery temperature, and compared with natural heat dissipation, the heat dissipation efficiency is greatly improved. It has been verified that the heat dissipation efficiency can be improved by 50%.

[0038] As can be seen, the bottom heat-conducting components and the water-cooling pipes on the inner wall of the bottom of the casing work together to form a highly efficient and reliable heat dissipation system. The bottom thermally conductive silicone pad, with its corrosion resistance, good thermal conductivity, and flexibility, effectively conducts heat from the bottom of the core to the inner wall of the bottom of the casing; while the water-cooling pipes quickly remove heat through forced convection, providing strong protection for the safe and stable operation of the prismatic battery, extending its lifespan, and improving its overall performance.

[0039] In a preferred embodiment of this utility model, the heat-conducting component 5 and the water-cooling pipe are separated by an aluminum plate (not shown in the figure). Considering that the heat-conducting component 5 is a thermally conductive silicone pad with a relatively soft material, the aluminum plate can be used to fix and support the thermally conductive silicone pad. Its shape is not limited.

[0040] This utility model also provides a battery pack, including the above-mentioned prismatic lithium-ion battery.

[0041] The above description is only a preferred embodiment of the present utility model and does not limit the implementation method and protection scope of the present utility model. Those skilled in the art should realize that all solutions obtained by equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present utility model.

Claims

1. A square-shell lithium-ion battery with enhanced thermal conductivity, comprising a top cover and positive and negative electrode connecting pieces; characterized in that, A first heat-conducting plate is provided between the top cover of the housing and the positive and negative electrode connecting pieces, and the first heat-conducting plate at least covers the welding area between the positive and negative electrode connecting pieces and the positive and negative electrode tabs.

2. The prismatic lithium-ion battery according to claim 1, characterized in that, The two sides of the first heat-conducting plate are respectively in contact with the top cover of the housing and the positive and negative electrode connecting pieces.

3. The prismatic lithium-ion battery according to claim 2, characterized in that, It also includes a second heat-conducting plate, which is disposed on the inner wall of both sides of the narrow face of the housing.

4. The prismatic lithium-ion battery according to claim 3, characterized in that, The first heat-conducting plate and the second heat-conducting plate are made of pad material.

5. The prismatic lithium-ion battery according to claim 4, characterized in that, The pad material is a carbon fiber thermally conductive material or a thermally conductive phase change material.

6. The prismatic lithium-ion battery according to claim 1, characterized in that, The housing contains a core, and a heat-conducting element is provided between the bottom of the core and the inner wall of the housing.

7. The prismatic lithium-ion battery according to claim 6, characterized in that, The thermally conductive component is a thermally conductive silicone pad.

8. The prismatic lithium-ion battery according to claim 6, characterized in that, The bottom inner wall of the shell is equipped with a water-cooling pipe.

9. The prismatic lithium-ion battery according to claim 8, characterized in that, The heat-conducting component and the water-cooling pipe are separated by an aluminum plate.

10. A battery pack, characterized in that, Including the prismatic lithium-ion battery as described in any one of claims 1-9.

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