Battery with phase change material, battery pack and thermal management method

Abstract

The invention relates to a battery with a phase change material, which comprises a pair of soft package batteries, at least one phase change material heat exchange plane layer is arranged between the pair of soft package batteries, and a pair of heat conduction silica gel heat transfer plane layers is also arranged between the phase change material heat exchange plane layer and the pair of soft package batteries. The invention also provides a battery pack composed of the batteries and a thermal management method for the batteries. The problems that a battery phase change material is low in heat conductivity coefficient and low in flexibility, and a liquid phase change material is prone to leakage are effectively solved, and the problem that the temperature of a soft package battery is uneven due to uneven heat production is thoroughly solved.

Description

Technical Field

[0001] The present invention relates to the field of battery thermal management, and in particular to a battery and a battery pack made of composite phase change materials. Background Art

[0002] With the rapid development of electric vehicles and energy storage technology, the safety, stability and service life of power batteries as key energy storage devices have received widespread attention. Power batteries generate heat due to chemical reactions during the charging and discharging process, especially at high-rate charging and discharging, where the heat generation is more significant. If the heat is not dissipated in a timely and effective manner, the battery temperature will rise, which will affect the battery's performance, life and even safety. Therefore, effective thermal protection must be provided for power battery packs.

[0003] When absorbing or releasing heat, phase change materials can undergo phase change (such as from solid to liquid) within a fixed temperature range. This process can effectively regulate the temperature of power batteries. Among them, organic phase change materials paraffin are widely used due to their moderate phase change temperature, high latent heat value, low cost and ideal chemical properties. However, the thermal conductivity of paraffin [0.1~0.3W / (m·K)] is low, which makes it unable to efficiently absorb the heat generated by the battery during operation and has poor temperature control performance; paraffin with low thermal conductivity cannot transfer the heat generated by the battery to the entire material in time, so the heat will accumulate near the contact surface between the battery and the paraffin. This heat accumulation will cause the temperature of this area to rise, while the temperature of other areas is relatively low, making it difficult to achieve uniform temperature of the battery; secondly, due to the uneven surface of the battery itself and the uneven surface that paraffin may form during the phase change process, the uneven surface will lead to a reduction in the contact area, so that the phase change material cannot quickly absorb and transfer the heat generated by the battery, affecting the efficiency of the phase change material in cooling the battery; at the same time, the fluidity of the molten paraffin will cause the paraffin to leak after absorbing heat and changing from a crystalline state to an amorphous state.

[0004] As the use time of power batteries increases, the difference in heat generation rate in different areas gradually increases, and safety has become a crucial consideration. However, phase change materials with low thermal conductivity cannot meet the high requirements of current electric vehicles for heat dissipation performance and safety. Therefore, composite phase change materials with high thermal conductivity and no leakage must be used to cool the battery, further control the battery temperature, and improve the battery temperature uniformity. Summary of the invention

[0005] The purpose of the present invention is to avoid the shortcomings of the prior art and provide a composite phase change material based on an octahedral truss structure to achieve battery phase change cooling and improve the battery temperature uniformity. The composite phase change material battery, battery pack and thermal management method.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a battery with phase change material, including a pair of soft-pack batteries with a thickness of 6 to 15 mm, at least one phase change material heat exchange plane layer is provided between the pair of soft-pack batteries, and a pair of heat conductive silicone heat transfer plane layers with a thickness of 0.5 to 1.5 mm are also provided between the phase change material heat exchange plane layer and the pair of soft-pack batteries; The phase change material heat exchange plane layer is composed of a sealed shell and a composite phase change material in the sealed shell cavity, and the thickness of the phase change material heat exchange plane layer is 2 to 10 mm, and the composite phase change material is a paraffin and truss plane layer; At the same time, the plane where the heat-conductive silicone heat transfer plane layer, the phase change material heat exchange plane layer and the soft-pack battery contact each other is the heat exchange surface, and the surface areas of the heat exchange surfaces are matched.

[0007] Furthermore, the phase change material heat exchange plane layer also includes at least one truss plane layer provided in the cavity of the sealed shell, and paraffin with a density of 0.88 to 0.92 g / cm3 is filled in the truss plane layer and fills the sealed shell cavity; The truss plane layer is composed of multiple truss monomers arranged in a matrix.

[0008] Furthermore, the preparation process of the phase change material heat exchange plane layer is as follows: First, heat the temperature of paraffin to above 80°C to completely melt the paraffin; Next, the truss plane layer is placed into the cavity of the sealed shell after drying, and liquid paraffin is then injected into the cavity; Then, the sealed shell containing the liquid paraffin and the truss plane layer is placed in a vacuum box, and the drying temperature is 60-70°C and 8-10×10 4 The vacuum pressure of Pa expels bubbles in the phase change material; Finally, the heat exchange layer of the phase change material of the paraffin / truss plane layer is obtained by naturally cooling to room temperature, removing excess solid paraffin, and sealing the shell.

[0009] Furthermore, the truss monomer includes: an octahedral central structure constructed by 36 truss rods and eight tetrahedral structures outside the octahedral central structure, wherein one tetrahedral structure is constructed by 6 truss rods; The three truss connection points of each face of the octahedral central structure are the three truss endpoints of a tetrahedral structure, and the truss connection points of the tetrahedral structure are the outer contour endpoints of the truss monomer, so that the outer contour of the truss monomer forms a cube structure; then, two truss monomers are connected to each other through the outer contour endpoints of the truss monomers to form a truss plane layer.

[0010] Furthermore, the matrix arrangement of the plurality of truss monomers is specifically as follows:x is the horizontal flow arrangement spacing of the truss monomer, S y is the span arrangement spacing of the truss monomer perpendicular to its horizontal direction, d is the truss diameter of the truss monomer, L is the length of the 411 truss rod of the octahedral central structure, β is the angle between the truss rod of the octahedral central structure and the vertical direction, then the setting distance between two truss monomers in the horizontal direction and the span direction is: , .

[0011] Furthermore, the angle β is 30-80°; the length of the truss rod of the octahedral central structure is L, and n is the number of truss monomers arranged in the thickness direction. is the thickness of the phase change material heat transfer plane layer, then ; Where n is 1 to 5.

[0012] Furthermore, the material of the heat-conductive silicone heat transfer plane layer is boron nitride, which is used to reduce the thermal resistance between the contact soft-pack battery and the phase change material heat exchange plane layer, thereby improving the heat dissipation efficiency.

[0013] The present invention also provides a battery pack composed of the batteries with phase change materials, the battery pack includes at least three soft-pack batteries, a pair of thermally conductive silicone heat transfer plane layers are provided between every two soft-pack batteries, and a phase change material heat exchange plane layer is sandwiched between the thermally conductive silicone heat transfer plane layers.

[0014] The present invention also provides a thermal management method of the battery having the phase change material. The soft-pack battery will continuously generate heat during operation, and the heat will be transferred to the phase change material heat exchange plane layer through the heat conductive silicone heat transfer plane layer. As the heat is absorbed, the temperature of the phase change material heat exchange plane layer gradually rises. When the temperature of the phase change material heat exchange plane layer reaches the phase change temperature point of the phase change material of 42°C, the phase change material begins to absorb heat at a constant temperature. At this time, the phase change material gradually changes from solid to liquid, realizing the phase change heat transfer of the soft-pack battery. The coordinated heat absorption of the thermal conductive silicone heat transfer plane layer and the phase change material heat exchange plane layer effectively controls the operating temperature of the soft-pack battery to less than or equal to 50°C.

[0015] Furthermore, the soft-pack battery will continuously generate heat during operation. Due to the uneven heat generation of the soft-pack battery, the surface temperature of the battery is unevenly distributed. The temperature at the center of the soft pack is high, and the temperature gradually decreases along the surrounding area, wherein the temperature near the negative electrode ear is the lowest. The heat exchange plane layer of the phase change material gradually absorbs the heat generated by the soft-pack battery. At this time, the ratio of the diameter d to the height h of the truss monomers in the truss plane layer inside the heat exchange plane layer of the phase change material ranges from 0.08 to 0.174; the porosity of the formed truss plane layer ranges from 0.980 to 0.900, which is used to absorb the heat in the high-temperature area of the soft-pack battery and transfer it to the surrounding composite phase change material with a lower temperature, making the temperature distribution on the surface of the soft-pack battery more uniform and avoiding local overheating of the soft-pack battery. Meanwhile, when the temperature of the heat exchange plane layer of the phase change material reaches the phase change temperature point of 42 °C of the phase change material, the phase change material begins to absorb heat at a constant temperature and gradually changes from a solid state to a liquid state. Relying on the truss plane layer, it prevents the phase change leakage of the composite phase change material filled in the voids surrounded by the truss monomers.

[0016] The beneficial effects of the present invention are as follows: 1. It can effectively solve the problem of low thermal conductivity of paraffin. Since the octahedral truss structure has a high thermal conductivity, and by utilizing the anisotropic thermal conductivity characteristics of this structure and combining paraffin with the octahedral truss structure, the thermal conductivity of paraffin can be effectively improved.

[0017] 2. It can effectively solve the problem of easy leakage of liquid-phase paraffin. Since there are abundant pore spaces in the octahedral truss structure, it can effectively adsorb paraffin, thus significantly reducing the risk of liquid-phase paraffin leakage. As a support framework, this structure not only enhances the integrity of paraffin but also significantly improves its structural stability.

[0018] 3. It can effectively solve the contact thermal resistance problem between the phase change material and the soft-pack battery. A thermal conductive silica gel sheet is arranged between the soft-pack battery and the composite phase change material. The thermal conductive silica gel sheet is soft in texture and can well fill the gap between the soft-pack battery and the composite phase change material, reducing the contact thermal resistance and improving the heat dissipation efficiency.

[0019] 4. It can effectively solve the problem of uneven battery temperature caused by uneven heat generation of the soft-pack battery. Since the composite phase change material is closely attached to the soft-pack battery through the thermal conductive silica gel sheet, the composite phase change material will gradually absorb the heat generated by the battery. At the same time, relying on the octahedral truss structure framework inside it, the heat inside the material can be effectively transferred, making the temperature distribution inside the battery pack more uniform and avoiding local overheating. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the battery structure of the composite phase change material of the present invention; Figure 2 It is an exploded schematic diagram of the battery structure of the composite phase change material of the present invention; Figure 3 It is a structural diagram of the truss monomer of the present invention; Figure 4 This is a planar structural diagram of the truss of the present invention; Figure 5 This is a schematic diagram of the battery pack structure of the present invention; Figure 6 This is a temperature distribution cloud diagram of the discharge simulation of the soft-pack battery of the present invention; Figure 7 The thermocouple arrangement diagram during the discharge process of the soft pack battery of the present invention; Figure 8 This is the battery discharge temperature curve of the specific example 1 of the present invention; Fig. 9 This is the battery discharge temperature curve of specific example 2 of the present invention.

[0021] In the figure: 1-soft-pack battery, 2-thermal conductive silicone heat transfer plane layer, 3-phase change material heat exchange plane layer, 31-sealed shell, 4-truss plane layer, 41-truss monomer, 411-octahedral central structure, 412-tetrahedral structure. DETAILED DESCRIPTION

[0022] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0023] The present invention is based on a battery of composite phase change material, that is, a phase change material heat exchange plane layer 3 and a heat conductive silicone heat transfer plane layer 2 are arranged in the middle of a soft pack battery 1. On the one hand, a heat conductive silicone heat transfer plane layer 2 is arranged between the phase change material heat exchange plane layer 3 and the soft pack battery 1. By using the heat conductive silicone heat transfer plane layer 2 to bond with the former two, the contact thermal resistance between the phase change material heat exchange plane layer 3 and the soft pack battery 1 can be reduced, and the heat conduction efficiency can be improved; on the other hand, the thermal conductivity of paraffin is enhanced by the octahedral truss structure, paraffin leakage is prevented, and heat dissipation efficiency is improved. At the same time, the octahedral truss structure has a rich pore space structure, and using it as a supporting skeleton improves the integrity, structural stability and anti-leakage performance of the composite phase change material.

[0024] In order to achieve the above object, the present invention provides the following specific implementation methods: Example 1: Figure 1 As shown, a battery with phase change material includes a pair of soft-pack batteries 1 with a thickness of 6 to 15 mm, at least one phase change material heat exchange plane layer 3 is provided between the pair of soft-pack batteries 1, and a pair of heat conductive silicone heat transfer plane layers 2 with a thickness of 0.5 to 1.5 mm are further provided between the phase change material heat exchange plane layer 3 and the pair of soft-pack batteries 1; the heat conductive silicone heat transfer plane layer 2 is made of boron nitride, which is used to reduce the thermal resistance between the contact soft-pack battery 1 and the phase change material heat exchange plane layer 3, and improve the heat dissipation efficiency; The phase change material heat exchange plane layer 3 is composed of a sealed shell 31 and a phase change material in the sealed shell cavity, and the thickness of the phase change material heat exchange plane layer 3 is 2 to 10 mm, and the phase change material is paraffin; At the same time, the plane where the heat-conducting silicone heat transfer plane layer 2, the phase change material heat exchange plane layer 3 and the soft-pack battery 1 contact each other is the heat exchange surface, and the surface areas of the heat exchange surfaces are matched.

[0025] Example 2: Figure 2 , Figure 3 , Figure 4 As shown, it is the same as Example 1, except that: the phase change material heat exchange plane layer 3 also includes at least one truss plane layer 4 provided in the cavity of the sealed shell, and paraffin with a density of 0.88 to 0.92 g / cm3 is filled in the truss plane layer and fills the cavity of the sealed shell; like Figure 2 As shown, the present invention utilizes paraffin coupled with an octahedral truss structure to manufacture a novel composite phase change material. On the one hand, the octahedral truss structure improves the thermal conductivity of paraffin, allowing heat to be conducted more quickly from the battery surface to the phase change material, thereby effectively managing the heat of the battery; on the other hand, due to the abundant pore space in the octahedral truss structure, paraffin can be effectively adsorbed, thereby significantly reducing the risk of leakage of liquid paraffin.

[0026] The truss plane layer 4 is composed of a plurality of truss monomers 41 arranged in a matrix.

[0027] like Figure 3 As shown, the truss monomer 41 includes: an octahedral central structure 411 constructed by 36 truss rods and eight tetrahedral structures 412 outside the octahedral central structure 411, wherein one tetrahedral structure 412 is constructed by 6 truss rods; The three truss connection points of each face of the octahedral central structure 411 are the three truss endpoints of a tetrahedral structure 412, and the truss connection points of the tetrahedral structure 412 are the outer contour endpoints of the truss monomer 41, so that the outer contour of the truss monomer 41 forms a cube structure; then, the two truss monomers are connected to each other through the outer contour endpoints of the truss monomers, forming a truss plane layer 4.

[0028] like Figure 4 As shown, the matrix arrangement of the multiple truss monomers 41 is specifically as follows: x is the horizontal flow arrangement spacing of the truss monomer, S y is the span arrangement spacing of the truss monomer perpendicular to its horizontal direction, d is the truss diameter of the truss monomer, L is the length of the 411 truss rod of the octahedral central structure, β is the angle between the truss rod of the octahedral central structure and the vertical direction, then the setting distance between two truss monomers in the horizontal direction and the span direction is: , .

[0029] The angle β is 30-80°; the length L of the truss rod of the octahedral central structure 411, n is the number of truss monomers 41 arranged in the thickness direction, is the thickness of the phase change material heat exchange plane layer 3, then ; Where n is 1 to 5.

[0030] As the β angle changes, the length of the truss rod changes, and the diameter of the truss rod changes, which in turn affects the changes in its structural porosity and thermal conductivity, and the heat storage capacity and thermal conductivity of the composite phase change material also change. When the form of the array structure changes, its thermal conductivity to paraffin will change, resulting in changes in internal heat dissipation. Therefore, the amount of paraffin used and the octahedral truss array structure in the truss plane layer in the phase change material heat exchange plane layer must be determined according to the heat dissipation requirements of the soft-pack battery.

[0031] Example 3: The same as Example 2, except that the preparation process of the phase change material heat exchange plane layer 3 is as follows: First, heat the temperature of paraffin to above 80°C to completely melt the paraffin; Next, the truss plane layer 4 is placed into the cavity of the sealed housing after drying, and liquid paraffin is then injected into the cavity; Then, the sealed shell containing the liquid paraffin and the truss plane layer 4 is placed in a vacuum box, and the drying temperature is 60 to 70°C and 8 to 10×10 4 The vacuum pressure of Pa expels bubbles in the phase change material; Finally, it is cooled naturally to room temperature, and excess solid paraffin is removed, and the shell is sealed to obtain the phase change material heat exchange plane layer 3 of the paraffin / truss plane layer.

[0032] Example 4: Figure 5 As shown, the present invention also provides a battery pack composed of batteries with phase change materials provided in Example 1, Example 2 and Example 3, the battery pack includes at least three soft-pack batteries 1, a pair of thermally conductive silicone heat transfer plane layers 2 are provided between every two of the soft-pack batteries 1, and a phase change material heat exchange plane layer 3 is sandwiched between the thermally conductive silicone heat transfer plane layers 2.

[0033] like Figure 5 As shown, the battery pack composed of the battery cells provided by the present invention can be flexibly combined and stacked according to the specific energy requirements, spatial layout or performance parameters in the actual application scenario because the battery cells are highly modular and scalable.

[0034] Embodiment 5: The present invention also provides a thermal management method for a battery having a phase change material as provided in Embodiment 1, The soft-pack battery 1 will continuously generate heat during operation, and the heat will be transferred to the phase change material heat exchange plane layer 3 through the heat conductive silicone heat transfer plane layer 2. As the heat is absorbed, the temperature of the phase change material heat exchange plane layer 3 gradually rises; When the temperature of the phase change material heat exchange plane layer 3 reaches the phase change temperature point of the phase change material 42°C, the phase change material begins to absorb heat at a constant temperature. At this time, the phase change material gradually changes from solid to liquid, realizing the phase change heat transfer of the soft-pack battery 1. The coordinated heat absorption of the thermal conductive silicone heat transfer plane layer 2 and the phase change material heat exchange plane layer 3 effectively controls the operating temperature of the soft-pack battery 1 to be less than or equal to 50°C.

[0035] Embodiment 6: The present invention also provides a thermal management method for a battery having a phase change material as provided in Embodiments 2 and 3. The soft-pack battery 1 will continuously generate heat during operation. The uneven heat generation of the soft-pack battery 1 leads to uneven temperature distribution on the battery surface. The temperature at the center of the soft-pack is high, and the temperature gradually decreases along the periphery. The temperature near the negative electrode ear is the lowest. The phase change material heat exchange plane layer 3 gradually absorbs the heat generated by the soft-pack battery 1. At this time, the ratio of the diameter d to the height h of the truss monomer 41 in the truss plane layer 4 inside the phase change material heat exchange plane layer 3 varies in the range of: 0.08~0.174; the porosity of the formed truss plane layer 4 varies in the range of: 0.980~0.900, which is used to absorb the heat in the high temperature area of ​​the soft-pack battery 1 and transfer it to the composite phase change material with lower ambient temperature, so that the temperature distribution on the surface of the soft-pack battery 1 is more uniform, avoiding local overheating of the soft-pack battery 1; At the same time, when the temperature of the phase change material heat exchange plane layer 3 reaches the phase change temperature point of the phase change material 42°C, the phase change material begins to absorb heat at a constant temperature and gradually changes from solid to liquid, relying on the truss plane layer 4 to prevent the phase change leakage of the composite phase change material filled in the gap surrounded by the truss monomers.

[0036] In the process of making batteries, soft-pack batteries of different sizes are taken to illustrate the technical effects of the present invention. Now, the present invention is described in detail with reference to specific examples and drawings: Specific example 1: (1) Take a pair of square soft-pack batteries 1 with a size of 110×60×12 mm, and set at least one phase change material heat exchange plane layer 3 between the pair of soft-pack batteries 1. The phase change material heat exchange plane layer 3 is composed of a sealed shell and a composite phase change material in the cavity of the sealed shell, and the thickness of the phase change material heat exchange plane layer 3 is 10 mm, and the composite phase change material is paraffin and a truss plane layer; The angle between the truss rod of the truss monomer of the truss plane layer 4 in the phase change material heat exchange plane layer 3 and the vertical direction is 45°, the truss diameter of the truss monomer 41 is 0.2 mm, the length of the truss rod of the octahedral central structure is 1.4 mm, the ratio of the truss monomer diameter d to the height h is 0.1, and the porosity surrounded by the truss monomer is 0.963, and the number of truss monomers arranged in the thickness direction is 5; (2) A pair of heat-conducting silicone heat-transfer plane layers with a thickness of 1 mm are provided between the phase change material heat-exchange plane layer 3 and the pair of soft-pack batteries 1; (3) The plane where the heat-conducting silicone heat transfer plane layer 2, the phase change material heat exchange plane layer 3 and the soft-pack battery 1 contact each other is the heat exchange surface, and the surface areas of the heat exchange surfaces are matched, that is, the length and width are both 110×60 mm; (4) Arrange a thermocouple at the soft-pack battery near the heat-conducting silicone heat transfer plane layer 2. The thermocouple is arranged at the following position: Figure 7 As shown, the composite phase change material coupled air-cooled battery is discharged using a 2C discharge rate.

[0037] After the discharge test analysis, the temperature data curve is as follows Figure 8 As shown in the figure, as the discharge time of the battery pack increases, its average temperature continues to increase. At a discharge rate of 2C, the cooling method of the composite phase change material can keep the maximum surface temperature of the battery within 49.7°C and the battery temperature difference within 0.7°C.

[0038] At the same time, in the initial stage of discharge, the battery surface has uneven temperature distribution due to uneven heat generation of the soft-pack battery. Under the action of the composite phase change material and thermal conductive silicone, the temperature difference on the battery surface gradually decreases and the battery temperature is effectively controlled. This proves that the battery has significant temperature control effect.

[0039] Specific example 2: (1) Take a pair of square soft-pack batteries 1 with a size of 260×165×10 mm, and set at least one phase change material heat exchange plane layer 3 between the pair of soft-pack batteries 1. The phase change material heat exchange plane layer 3 is composed of a sealed shell and a composite phase change material in the cavity of the sealed shell, and the thickness of the phase change material heat exchange plane layer is 10 mm, and the composite phase change material is paraffin and a truss plane layer; The angle between the truss rod of the truss monomer 41 of the truss plane layer in the phase change material heat exchange plane layer 3 and the vertical direction is 45°, the truss diameter of the truss monomer is 0.4 mm, the length of the truss rod of the octahedral central structure is 1.77 mm, the ratio of the truss monomer diameter d to the height h is 0.16, and the porosity surrounded by the truss monomer is 0.912, and the number of truss monomers 41 arranged in the thickness direction is 4; (2) A pair of heat-conducting silicone heat-transfer plane layers 2 with a thickness of 1 mm are provided between the phase change material heat-exchange plane layer 3 and the pair of soft-pack batteries 1; (3) The plane where the heat transfer plane layer of the thermally conductive silicone rubber, the heat transfer plane layer of the phase change material and the soft-pack battery are in contact with each other is the heat transfer surface, and the surface areas of the heat transfer surfaces are matched, that is, the length and width are both 260×165 mm; (4) Arrange a thermocouple at the soft-pack battery near the heat-conducting silicone heat transfer plane layer 2. The thermocouple is arranged at the following position: Figure 7 As shown, the composite phase change material coupled air-cooled battery is discharged using a 2C discharge rate.

[0040] After the discharge test analysis, the temperature data curve is as follows Fig. 9 As shown in the figure, as the discharge time of the battery pack increases, its average temperature continues to increase. At a discharge rate of 2C, the cooling method of composite phase change materials coupled with natural wind can keep the maximum surface temperature of the battery within 50°C and the battery temperature difference within 1°C.

[0041] At the same time, in the initial stage of discharge, the battery surface has uneven temperature distribution due to uneven heat generation of the soft-pack battery. Under the effect of composite phase change material coupled with air cooling, the temperature difference on the battery surface gradually decreases and the battery temperature is effectively controlled. This proves that the battery temperature control effect is significant.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery having a phase change material, characterized in that: It comprises a pair of soft-pack batteries (1) with a thickness of 6 to 15 mm, at least one phase change material heat exchange plane layer (3) is provided between the pair of soft-pack batteries (1), and a pair of heat conductive silicone heat transfer plane layers (2) with a thickness of 0.5 to 1.5 mm are also provided between the phase change material heat exchange plane layer (3) and the pair of soft-pack batteries (1); The phase change material heat exchange plane layer (3) is composed of a sealed shell (31) and a composite phase change material in the cavity of the sealed shell, and the thickness of the phase change material heat exchange plane layer (3) is 2 to 10 mm, and the composite phase change material is paraffin and a truss plane layer; At the same time, the plane where the heat-conducting silica gel heat transfer plane layer (2), the phase change material heat exchange plane layer (3) and the soft-pack battery (1) contact each other is the heat exchange surface, and the surface areas of the heat exchange surfaces are arranged to match each other.

2. The battery having a phase change material as claimed in claim 1, characterized in that: The phase change material heat exchange plane layer (3) further comprises at least one truss plane layer (4) provided in the cavity of the sealed shell, paraffin with a density of 0.88 to 0.92 g / cm3 is filled in the truss plane layer and fills the cavity of the sealed shell; The truss plane layer (4) is composed of a plurality of truss monomers (41) arranged in a matrix.

3. The battery having a phase change material as claimed in claim 2, characterized in that: The preparation process of the phase change material heat exchange plane layer (3) is as follows: First, heat the temperature of paraffin to above 80°C to completely melt the paraffin; Next, the truss plane layer (4) is placed in the cavity of the sealed housing after drying, and liquid paraffin is then injected into the cavity; Then, the sealed shell containing the liquid paraffin and the truss plane layer (4) is placed in a vacuum box and dried at a temperature of 60 to 70°C and 8 to 10 4 The vacuum pressure of Pa expels bubbles in the phase change material; Finally, the heat exchange layer (3) of the phase change material of the paraffin / truss plane layer is obtained by naturally cooling to room temperature, removing excess solid paraffin, and sealing the shell.

4. The battery with phase change material as claimed in claim 2, characterized in that: The truss monomer (41) comprises: an octahedral central structure (411) constructed by 36 truss rods and eight tetrahedral structures (412) outside the octahedral central structure (411), wherein one tetrahedral structure (412) is constructed by 6 truss rods; The three truss connection points of each face of the octahedral central structure (411) are the three truss end points of a tetrahedral structure (412), and the truss connection points of the tetrahedral structure (412) are the outer contour end points of the truss monomer (41), so that the outer contour of the truss monomer (41) forms a cube structure; then, two truss monomers are connected to each other through the outer contour end points of the truss monomers, forming a truss plane layer (4).

5. The battery having a phase change material as claimed in claim 4, characterized in that: The matrix arrangement of the plurality of truss monomers (41) is specifically as follows: x is the horizontal flow arrangement spacing of the truss monomer, S y is the span arrangement spacing of the truss monomer perpendicular to its horizontal direction, d is the truss diameter of the truss monomer, L is the length of the 411 truss rod of the octahedral central structure, β is the angle between the truss rod of the octahedral central structure and the vertical direction, then the setting distance between two truss monomers in the horizontal direction and the span direction is: ， 。 6. The battery having a phase change material as claimed in claim 5, characterized in that: The angle β is 30-80°; the truss rod length L of the octahedral central structure (411), n ​​is the number of truss monomers (41) arranged in the thickness direction, is the thickness of the phase change material heat exchange plane layer (3), then ; Where n is 1 to 5.

7. The battery having a phase change material according to any one of claims 1 to 6, characterized in that: The material of the heat-conducting silica gel heat transfer plane layer (2) is boron nitride, and is used to reduce the thermal resistance between the contact soft-pack battery (1) and the phase change material heat exchange plane layer (3), thereby improving the heat dissipation efficiency.

8. A battery pack composed of batteries with phase change materials, characterized in that: The battery pack comprises at least three soft-pack batteries (1), a pair of heat-conducting silicone heat transfer plane layers (2) are provided between every two of the soft-pack batteries (1), and a phase change material heat exchange plane layer (3) is sandwiched between the heat-conducting silicone heat transfer plane layers (2).

9. A thermal management method for a battery having a phase change material according to claims 1, 3-7, characterized in that: The soft-pack battery (1) will continuously generate heat during operation, and the heat will be transferred to the phase change material heat exchange plane layer (3) through the heat conductive silica gel heat transfer plane layer (2). As the heat is absorbed, the temperature of the phase change material heat exchange plane layer (3) gradually rises. When the temperature of the phase change material heat exchange plane layer (3) reaches the phase change temperature point of the phase change material, 42°C, the phase change material begins to absorb heat at a constant temperature. At this time, the phase change material gradually changes from a solid state to a liquid state, thereby achieving phase change heat transfer for the soft-pack battery (1). The coordinated heat absorption of the heat conductive silicone heat transfer plane layer (2) and the phase change material heat exchange plane layer (3) effectively controls the operating temperature of the soft-pack battery (1) to be less than or equal to 50°C.

10. A thermal management method for a battery having a phase change material according to claims 2, 3-7, characterized in that: The soft-pack battery (1) will continuously generate heat during operation. The uneven heat generation of the soft-pack battery (1) leads to uneven temperature distribution on the battery surface. The temperature at the center of the soft pack is high, and the temperature gradually decreases along the periphery. The temperature is lowest in the area close to the negative electrode ear. The phase change material heat exchange plane layer (3) gradually absorbs the heat generated by the soft pack battery (1). At this time, the ratio of the diameter d to the height h of the truss monomer (41) in the truss plane layer (4) inside the phase change material heat exchange plane layer (3) varies in the range of 0.08 to 0.174; the porosity of the formed truss plane layer (4) varies in the range of 0.980 to 0.900, and is used to absorb the heat in the high temperature area of ​​the soft pack battery (1) and transfer it to the composite phase change material with a lower ambient temperature, so that the temperature distribution on the surface of the soft pack battery (1) is more uniform, thereby avoiding local overheating of the soft pack battery (1); At the same time, when the temperature of the phase change material heat exchange plane layer (3) reaches the phase change temperature point of the phase change material, 42°C, the phase change material begins to absorb heat at a constant temperature and gradually changes from a solid state to a liquid state, relying on the truss plane layer (4) to prevent the phase change leakage of the composite phase change material filled in the gap surrounded by the truss monomers.

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