Composite phase change material coupled air cooling battery, battery pack and thermal management method

Abstract

The invention relates to a composite phase change material coupled air cooling battery, which comprises a truss type air cooling plane layer arranged between a pair of soft package batteries and used for convection heat exchange ventilation between the batteries, and a pair of phase change material heat exchange plane layers arranged between the truss type air cooling plane layer and the pair of soft package batteries, the invention also provides a battery pack formed based on the battery and a thermal management method. By adopting a phase change-air cooling mode, the cooling efficiency of the battery is effectively improved, the problems that a battery phase change material is low in heat conductivity coefficient and flexibility and a liquid phase change material is easy to leak are effectively solved, and the problem that the temperature of the battery is nonuniform due to nonuniform heat production of the soft package battery 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 having a composite phase change material and an air cooling structure. Background Art

[0002] Traditional battery cooling methods mainly include air cooling, liquid cooling, etc. The mainstream air-cooled battery thermal management system on the market is an active air-cooled heat dissipation system based on the vehicle air-conditioning compressor as the cooling source + sealed pipeline + air + fan. The vehicle air-conditioning compressor can effectively cool the air, and then with the help of the pipeline inside the power battery, the air carrying the cold capacity can be effectively and accurately guided to the power battery, further taking away the heat generated by the battery. However, there is no turbulent structure in the sealed pipeline, and the heat exchange efficiency is low, resulting in a large capacity battery generating much more heat than the heat taken away by the air cooling during high-rate charging and discharging, which leads to serious safety hazards; at the same time, the energy consumption required to cool the air using the vehicle air-conditioning compressor is large, which will greatly consume the power in the battery, and thus seriously shorten the range of electric vehicles; secondly, in the air-cooling system, the air flow rate may be different in different areas of the battery. Areas with higher flow rates may take away more heat, while areas with lower flow rates may cause heat accumulation, making it difficult to achieve temperature uniformity of the battery.

[0003] Phase change materials are widely studied for thermal management of batteries because they can absorb and release a large amount of heat near the phase change temperature without causing significant temperature changes. However, there is currently no better phase change material that can be officially used in electric vehicles.

[0004] With the continuous innovation and optimization of battery technology, the overall capacity of power batteries is increasing day by day. At the same time, the development of fast charging technology has also increased the charging and discharging rate of batteries, which has led to a gradual increase in the heat generated by the batteries when they are working. Pure air cooling technology is difficult to meet the heat dissipation requirements of high-power density batteries. Therefore, a composite cooling method of phase change cooling coupled with air cooling must be applied, that is, to achieve better cooling effects with as little energy consumption as possible and reduce the temperature of power batteries to the greatest extent. 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 coupled air-cooled battery, battery pack and thermal management method that combines phase change cooling material and air-cooling channel truss structure to achieve battery composite cooling, enhance the convective heat exchange of air inside the battery, and improve the temperature uniformity of the battery.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a composite phase change material coupled air-cooled battery, comprising a pair of soft-pack batteries with a thickness of 6 to 15 mm, at least one truss-type air-cooled plane layer for convection heat exchange and ventilation between the batteries is provided between the pair of soft-pack batteries, and the thickness of the truss-type air-cooled plane layer is 2.5 to 6 mm; a pair of phase change material heat exchange plane layers are also provided between the truss-type air-cooled plane layer and the pair of soft-pack batteries; Among them, the truss-type air-cooled plane layer is composed of a plurality of truss monomers arranged in a matrix; the phase change material heat exchange plane layer 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 2 to 10 mm, and the composite phase change material is paraffin and thermoplastic rubber material with a mass ratio of 4 to 6:4 to 6; At the same time, the plane where the truss-type air-cooling plane layer, the phase change material heat exchange plane layer and the soft-pack battery are in contact with 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 sealed shell cavity, the truss plane layer has the same structure as the truss type air-cooled plane layer, and the composite phase change material with a density of 0.9 to 0.928 g / cm3 is filled in the truss plane layer and fills the sealed shell cavity.

[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, liquid phase paraffin and powdered thermoplastic rubber are stirred and mixed at a mass ratio of 4-6:4-6, and stirred for at least 30 minutes at a temperature above 80° C. to uniformly mix the thermoplastic rubber in the paraffin, thereby obtaining a liquid phase composite phase change material of paraffin / thermoplastic rubber; Then, the truss plane layer is placed into the cavity of the sealed housing, and then the composite phase change material of liquid paraffin / thermoplastic rubber is injected into the cavity of the sealed housing; The sealed shell containing the composite phase change material of liquid paraffin / thermoplastic rubber and the truss plane layer is placed in a vacuum box. 6 The vacuum pressure of Pa discharges the bubbles in the composite phase change material; Finally, the phase change material is naturally cooled to room temperature, and excess solid composite phase change material is removed, and the shell is sealed to obtain a phase change material heat exchange plane layer of paraffin / thermoplastic rubber / truss plane layer.

[0009] The thermoplastic rubber material used in the present invention mainly refers to: styrene-ethylene / butylene-styrene triblock copolymer, EPDM rubber and thermoplastic vulcanized rubber, etc., which have good flexibility and are all materials available on the market.

[0010] 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, forming a truss-type air-cooled plane layer; Then, the matrix arrangement of multiple truss monomers is 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 truss rod of the octahedron central structure, β is the angle between the truss rod of the octahedron 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 to 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 composite phase change material layer, then ; Where n is 1 to 5.

[0012] Furthermore, the sealing shell is provided with a slot for facilitating the installation of a plurality of the truss units, the depth of the slot is half the diameter of the truss rod constituting the truss unit, and the arrangement of the slot is matched with the arrangement shape of the plurality of truss units.

[0013] Furthermore, the present invention also provides a battery pack consisting of composite phase change material coupled air-cooled batteries, the battery pack comprising at least three soft-pack batteries, a pair of phase change material plane layers being provided between every two of the soft-pack batteries, and a truss-type air-cooled plane layer being sandwiched between the phase change material plane layers.

[0014] Furthermore, the present invention also provides a thermal management method for a battery coupled with air cooling by the composite phase change material, wherein the soft-pack battery will continuously generate heat during operation, and the phase change material plane layer will continuously absorb heat, so that the temperature of the phase change material plane layer gradually rises; When the temperature of the plane layer of the phase change material 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 the state of the phase change material gradually changes from solid to liquid. At the same time, during the heat absorption process, the phase change material plane layer continuously releases heat which will be continuously transferred to the truss-type air-cooled plane layer with relatively low temperature. The heat is cooled by air heat exchange in the truss-type air-cooled plane layer, realizing the composite heat exchange of phase change and air cooling for the soft-pack battery, and effectively controlling the operating temperature of the soft-pack battery to less than or equal to 45°C.

[0015] Furthermore, when heat flows from the phase change material plane layer into the truss-type air-cooled plane layer, the cold air flow flowing into the truss monomer contacts the surface of the truss monomer having heat. At this time, the ratio of the diameter d to the height h of the truss monomer in the truss-type air-cooled plane layer varies in the range of 0.20 to 0.24, so as to increase the area of ​​the truss monomer contacting the heat, increase the temperature of the truss monomer in the truss-type air-cooled plane layer, and finally transfer the heat from the surface of the truss monomer to the cold air flow; After the cold air flow passing through the surface of the truss monomer is heated, the temperature of the cold air flow increases, the density decreases, and the air expands. At this time, the porosity formed by the truss monomer varies in the range of 0.887 to 0.843, which is used to increase the flow resistance in the channel formed by the truss monomer, and make the cold air flow have a velocity gradient and a pressure gradient after passing through the truss monomer. After the cold air flow is heated, a longitudinal vortex of rotating fluid micro-clusters is formed in the pores formed by the truss monomer, and the vortex rotation axis of the longitudinal vortex is parallel to the flow direction of the air flow, which promotes the air flow rate and improves the heat exchange efficiency.

[0016] Furthermore, the present invention also provides another method for thermal management of a battery coupled with air cooling by the composite phase change material. 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 phase change material heat exchange plane layer 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 monomer in the truss plane layer inside the phase change material heat exchange plane layer varies in the range of: 0.08 to 0.174; the porosity of the formed truss plane layer varies in the range of: 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 composite phase change material with lower ambient temperature, so that the temperature distribution on the surface of the soft-pack battery is more uniform, avoiding local overheating of the soft-pack battery; At the same time, when the temperature of the phase change material plane layer 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 to prevent the phase change leakage of the composite phase change material filled in the gap surrounded by the truss monomers.

[0017] The beneficial effects of the present invention are: 1. It can effectively solve the problems of low thermal conductivity and low flexibility of phase change materials. Since the octahedral truss structure has a high thermal conductivity, and the anisotropic thermal conductivity of the structure is utilized, the phase change material is combined with the octahedral truss structure to effectively improve the thermal conductivity of the composite phase change material. The thermoplastic rubber material has good flexibility, which can further improve the thermal stability and flexibility of the composite phase change material and the fit with the soft pack battery.

[0018] 2. It can effectively solve the problem of easy leakage of liquid phase change materials. Due to the abundant pore space in the octahedral truss structure, it can effectively adsorb the composite phase change material, thereby significantly reducing the risk of leakage of the liquid phase change material. This structure, as a supporting skeleton, not only enhances the integrity of the composite phase change material, but also significantly improves its structural stability.

[0019] 3. It can effectively solve the problem of uneven battery temperature caused by uneven heat generation in soft-pack batteries. Since the composite phase change material fits tightly with the soft-pack battery, the composite phase change material will gradually absorb the heat generated by the battery. At the same time, relying on the octahedral truss structure skeleton inside it, it can effectively transfer the heat inside the material, making the temperature distribution inside the battery pack more uniform and avoiding local overheating.

[0020] 4. It can effectively solve the problem of low air cooling efficiency. Since the flow inside the octahedral truss array structure is a longitudinal vortex along the flow direction, the convection heat transfer of the air inside is strengthened, and the heat transfer efficiency is greatly improved.

[0021] 5. It can effectively reduce the energy consumption of battery thermal management. It adopts phase change-air cooling method, which does not rely on external power supply or power device, and helps to reduce the overall energy consumption while maintaining the stable operation of the battery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the composite phase change material coupled air-cooled battery structure; Figure 2 Schematic diagram of explosion of composite phase change material coupled air-cooled battery structure; Figure 3 It is the structure diagram of the octahedral truss unit cell; Figure 4 is the structural diagram of the octahedral truss array; Figure 5 This is a structural diagram of the groove at the bottom of the sealing shell; Figure 6 Cooling air flow diagram of composite phase change material coupled air-cooled battery; Figure 7 Cooling air flow diagram of composite phase change material coupled air-cooled battery pack; Figure 8Temperature distribution cloud diagram of soft pack battery discharge simulation; Fig. 9 Schematic diagram of cooling air flow in the truss-type air-cooled plane layer; Fig.10 Thermocouple arrangement diagram during discharge of soft pack battery; Fig.11 Specific Example 1 Battery discharge temperature curve; Fig.12 Specific example 2: Battery discharge temperature curve.

[0023] In the figure: 1 soft-pack battery, 2 phase change material heat exchange plane layer, 21 sealed shell, 22 truss plane layer, 23 slot, 3 truss air-cooled plane layer, 31 truss monomer, 311 octahedral central structure, 312 tetrahedral structure, 4 cold air flow, 5 heat flow, 6 cold air flow after heating, 7 longitudinal vortex. DETAILED DESCRIPTION

[0024] 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.

[0025] The present invention is based on a battery coupled with composite phase change material and air cooling, that is, a phase change material heat exchange plane layer and a truss-type air cooling plane layer are arranged in the middle of the soft-pack battery. On the one hand, the composite phase change material with appropriate proportion has good thermal conductivity, flexibility and anti-leakage, which enhances the fit with the soft-pack battery, improves the heat absorption capacity of the soft-pack battery and reduces the risk of phase change material leakage; on the other hand, the cold air flow can be disturbed by the truss-type air cooling plane layer, which strengthens the convection heat exchange of the air inside it and greatly improves the heat exchange efficiency.

[0026] At the same time, the combination of phase change cooling and air cooling can achieve complementary advantages. Phase change materials absorb heat when the battery temperature rises, slowing down the temperature rise and improving the temperature uniformity of the battery; the air cooling system uses natural air flow to take away the heat in the phase change material without additional energy consumption, which is conducive to reducing the overall energy consumption of the battery thermal management system.

[0027] In order to achieve the above object, the present invention provides the following specific implementation methods: Example 1: Figure 1 , Figure 3 , Figure 4As shown, a composite phase change material coupled air-cooled battery comprises a pair of soft-pack batteries 1 with a thickness of 6 to 15 mm, at least one truss-type air-cooled plane layer 3 for convection heat exchange and ventilation between the batteries is provided between the pair of soft-pack batteries 1, and the thickness of the truss-type air-cooled plane layer 3 is 2.5 to 6 mm; a pair of phase change material heat exchange plane layers 2 are also provided between the truss-type air-cooled plane layer 3 and the pair of soft-pack batteries 1, as shown in FIG. Figure 1 As shown; Among them, the truss-type air-cooled plane layer 3 is composed of a plurality of truss monomers 31 arranged in a matrix; the phase change material heat exchange plane layer 2 is composed of a sealed shell 21 and a composite phase change material in the sealed shell cavity, and the thickness of the phase change material heat exchange plane layer 2 is 2 to 10 mm, and the composite phase change material is paraffin and thermoplastic rubber material with a mass ratio of 4 to 6:4 to 6; At the same time, the plane where the truss-type air-cooling plane layer 3, the phase change material heat exchange plane layer 2 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.

[0028] like Figure 3 As shown, the truss monomer 31 includes: an octahedral central structure 311 constructed by 36 truss rods and eight tetrahedral structures 312 outside the octahedral central structure 311, wherein one tetrahedral structure 312 is constructed by 6 truss rods; The three truss connection points of each face of the octahedral central structure 311 are the three truss endpoints of a tetrahedral structure 312, and the truss connection points of the tetrahedral structure 312 are the outer contour endpoints of the truss monomer 31, so that the outer contour of the truss monomer 31 forms a cube structure; then, two truss monomers 31 are connected to each other through the outer contour endpoints of the truss monomers, forming a truss-type air-cooled plane layer 3; So, if Figure 4 As shown, the matrix arrangement of the multiple truss monomers 31 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 monomers perpendicular to the horizontal direction, d is the truss diameter of the truss monomers, L is the length of the truss rod of the octahedral central structure, β is the angle between the truss rod of the octahedral central structure 311 and the vertical direction, then the setting distance between the two truss monomers 31 in the horizontal direction and the span direction is: , .

[0029] The angle β is 30 to 80°; the length of the truss rod of the octahedral central structure 311 is L, and n is the number of truss monomers arranged in the thickness direction. is the thickness of the composite phase change material layer, then ; Where n is 1 to 5.

[0030] The size of the nodes in the truss monomers 31 affects the mechanical stability and thermal conductivity of the structure, while the diameter of the truss rod and its angle with the vertical direction determine the size of the nodes; its array structure looks complex, but it is a regular periodic structure, that is, an overall structure composed of multiple truss monomers 31.

[0031] 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 energy conductivity of the composite phase change material also change; at the same time, it will also affect the convective heat transfer efficiency and flow resistance in the truss-type air-cooled plane layer.

[0032] When the form of the array structure changes, its heat dissipation performance for paraffin / thermoplastic rubber materials and air cooling will change, resulting in changes in internal heat dissipation. Therefore, the amount of composite phase change material, the truss plane layer in the phase change material heat exchange plane layer, and the octahedral truss array structure in the truss air cooling plane layer can all be determined according to the heat dissipation requirements of the soft-pack battery, and are all necessary features to determine the heat dissipation effect.

[0033] Example 2: Figure 2 As shown, it is the same as Example 1, except that: further, the phase change material heat exchange plane layer 2 also includes at least one truss plane layer 22 provided in the sealed shell cavity, the truss plane layer 22 is consistent with the structure of the truss type air-cooled plane layer 3, and the composite phase change material with a density of 0.9 to 0.928 g / cm3 is filled in the truss plane layer 22 and fills the sealed shell cavity.

[0034] The preparation process of the phase change material heat exchange plane layer 2 is as follows: First, heat the temperature of paraffin to above 80°C to completely melt the paraffin; Next, liquid phase paraffin and powdered thermoplastic rubber are stirred and mixed at a mass ratio of 4-6:4-6, and stirred for at least 30 minutes at a temperature above 80° C. to uniformly mix the thermoplastic rubber in the paraffin, thereby obtaining a liquid phase composite phase change material of paraffin / thermoplastic rubber; Then, the truss plane layer 22 is placed into the cavity of the sealed housing, and then the composite phase change material of liquid paraffin / thermoplastic rubber is injected into the cavity of the sealed housing; The sealed shell containing the composite phase change material of liquid paraffin / thermoplastic rubber and the truss plane layer is placed in a vacuum box. 6 The vacuum pressure of Pa discharges the bubbles in the composite phase change material; Finally, it is cooled naturally to room temperature, and excess solid composite phase change material is removed, and the shell is sealed to obtain the phase change material heat exchange plane layer 2 of the paraffin / thermoplastic rubber / truss plane layer.

[0035] Example 3: Figure 5 As shown, it is the same as Example 1, except that: a slot 23 is provided on the sealed shell 21 for convenient installation of multiple truss monomers 31, the depth of the slot 23 is half the diameter of the truss rod constituting the truss monomer 31, and the arrangement of the slot 23 is matched with the arrangement shape of the multiple truss monomers.

[0036] Example 4: Figure 7 As shown, the present invention also provides a battery pack composed of the composite phase change material coupled air-cooled battery of Example 1, the battery pack includes at least three soft-pack batteries 1, a pair of phase change material plane layers 3 are provided between every two soft-pack batteries 1, and a truss-type air-cooled plane layer 3 is sandwiched between the phase change material plane layers 3.

[0037] That is, Examples 1-3 provide a composite phase change material coupled air-cooled battery unit, which is highly modular and scalable, and can be flexibly combined and stacked to form a battery pack according to specific energy requirements, spatial layout or performance parameters in actual application scenarios.

[0038] Example 5: Figure 6 , Fig. 9 As shown, the present invention also provides a thermal management method for a battery coupled with air cooling by the composite phase change material of Example 1. The soft-pack battery 1 will continuously generate heat during operation, and the phase change material plane layer 2 will continuously absorb heat, so that the temperature of the phase change material plane layer 2 gradually rises; When the temperature of the phase change material plane layer 2 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 the state of the phase change material gradually changes from solid to liquid. At the same time, Figure 6 As shown, during the heat absorption process of the phase change material plane layer 2, the heat 5 continuously released will be continuously transferred to the truss-type air-cooled plane layer 3 with a relatively low temperature. The heat 5 is cooled by air heat exchange in the truss-type air-cooled plane layer 3, realizing the composite heat exchange of phase change-air cooling for the soft-pack battery 1, and effectively controlling the operating temperature of the soft-pack battery 1 to be less than or equal to 45°C.

[0039] like Fig. 9As shown, when the heat 5 flows from the phase change material plane layer 2 into the truss type air-cooled plane layer 3, the cold air flow 4 flowing into the truss monomer 31 contacts the surface of the truss monomer 31 having the heat 5. At this time, the ratio of the diameter d to the height h of the truss monomer 31 in the truss type air-cooled plane layer 3 varies in the range of 0.20 to 0.24, so as to increase the area of ​​the truss monomer 31 contacting the heat 5, so as to increase the temperature of the truss monomer 31 in the truss type air-cooled plane layer 3, and finally transfer the heat from the surface of the truss monomer 31 to the cold air flow 4; After the cold air flow 4 passing through the surface of the truss monomer 31 is heated, the temperature of the cold air flow 4 increases, the density decreases, and the air expands. At this time, the porosity formed by the truss monomer 31 varies in the range of 0.887 to 0.843, which is used to increase the flow resistance in the channel formed by the truss monomer 31, and make the cold air flow 4 have a velocity gradient and a pressure gradient after passing through the truss monomer 31. After the cold air flow 6 is heated, a longitudinal vortex 7 of rotating fluid micro-clusters is formed in the pores formed by the truss monomer 31, and the vortex rotation axis of the longitudinal vortex 7 is parallel to the flow direction of the air flow, which promotes the air flow rate and improves the heat exchange efficiency.

[0040] Example 6: Figure 8 As shown, the present invention also provides a thermal management method for a battery coupled with air cooling by the composite phase change material of Example 2. The soft-pack battery 1 will continuously generate heat during operation. Due to the uneven heat generation of the soft-pack battery 1, 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. The temperature near the negative electrode ear is the lowest. Figure 8 As shown; The phase change material heat exchange plane layer 2 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 in the truss plane layer 22 inside the phase change material heat exchange plane layer 2 varies in the range of: 0.08 to 0.174; the porosity of the formed truss plane layer 22 varies in the range of: 0.980 to 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 plane layer 2 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 22 to prevent the phase change leakage of the composite phase change material filled in the gap surrounded by the truss monomers.

[0041] The present invention utilizes paraffin, thermoplastic rubber material / octahedral truss structure to manufacture a novel composite phase change material. On the one hand, the thermoplastic rubber material provides good flexibility and elasticity, so that the composite material can adapt to the volume change of the battery during the charging and discharging process; on the other hand, the octahedral truss structure improves the thermal conductivity of the composite material, so that heat can be conducted from the battery surface to the phase change material more quickly, thereby effectively managing the heat of the battery.

[0042] 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 with a size of 227×161×12 mm, and set at least one truss-type air-cooling plane layer between the pair of soft-pack batteries for convective heat exchange and ventilation between the batteries. The truss-type air-cooling plane layer is composed of multiple truss monomers arranged in a matrix; The angle between the truss rod of the truss monomer in the truss-type air-cooled plane layer and the vertical direction is 45°, the truss diameter of the truss monomer is 1 mm, the length of the truss rod of the octahedral central structure is 3.5 mm, the ratio of the truss monomer diameter d to the height h is 0.2, and the porosity surrounded by the truss monomer is 0.887, and the thickness of the truss-type air-cooled plane layer is 5 mm; (2) A pair of phase change material heat exchange plane layers are also provided between the truss-type air-cooled 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 cavity of the sealed shell, and the thickness of the phase change material heat exchange plane layer is 9 mm. The composite phase change material is a triblock copolymer of paraffin wax and thermoplastic elastomer styrene-ethylene / butylene-styrene in a mass ratio of 6:4; The angle between the truss rod of the truss monomer in the truss plane layer inside the phase change material heat exchange plane layer and the vertical direction is 45°, the truss diameter of the truss monomer is 0.5 mm, the length of the truss rod of the octahedral central structure is 2 mm, the ratio of the truss monomer diameter d to the height h is 0.16, the porosity surrounded by the truss monomer is 0.912, and the number of truss monomers arranged in the thickness direction is 3; A card slot is provided on the sealed housing for facilitating installation of a plurality of the truss units, the depth of the card slot is half the diameter of the truss rod of the truss unit in the truss-type air-cooled plane layer, that is, the depth of the card slot is 0.5 mm, and the arrangement of the card slot matches the arrangement shape of the plurality of truss units; (3) The plane where the truss-type air-cooling 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 area of ​​the heat exchange surface is matched, that is, the length and width are both 227×161mm; (4) Arrange a thermocouple at the soft-pack battery near the phase change material heat exchange plane layer. The thermocouple arrangement position is as follows: Fig.10 As shown, the composite phase change material coupled air-cooled battery is discharged using a 2C discharge rate.

[0043] After the discharge test analysis, the temperature data curve is as follows Fig.11 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 45°C and the battery temperature difference within 1.6°C.

[0044] 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.

[0045] Specific example 2: (1) Take a pair of square soft-pack batteries with a size of 230×165×10mm, and set at least one truss-type air-cooling plane layer between the pair of soft-pack batteries for convective heat exchange and ventilation between the batteries. The truss-type air-cooling plane layer is composed of multiple truss monomers arranged in a matrix; The angle between the truss rod of the truss monomer in the truss-type air-cooled plane layer and the vertical direction is 45°, the truss diameter of the truss monomer is 1 mm, the length of the truss rod of the octahedral central structure is 3 mm, the ratio of the truss monomer diameter d to the height h is 0.22, and the porosity surrounded by the truss monomer is 0.865. The thickness of the truss-type air-cooled plane layer is 4.5 mm; (2) A pair of phase change material heat exchange plane layers are also provided between the truss-type air-cooled 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 cavity of the sealed shell, and the thickness of the phase change material heat exchange plane layer is 8 mm. The composite phase change material is a triblock copolymer of paraffin wax and thermoplastic elastomer styrene-ethylene / butylene-styrene in a mass ratio of 6:4; The angle between the truss rod of the truss monomer in the truss plane layer inside the phase change material heat exchange plane layer and the vertical direction is 45°, the truss diameter of the truss monomer is 0.5 mm, the length of the truss rod of the octahedral central structure is 2.83 mm, the ratio of the truss monomer diameter d to the height h is 0.125, the porosity surrounded by the truss monomer is 0.942, and the number of truss monomers arranged in the thickness direction is 2; A card slot is provided on the sealed housing for facilitating installation of a plurality of the truss units, the depth of the card slot is half the diameter of the truss rod of the truss unit in the truss-type air-cooled plane layer, that is, the depth of the card slot is 0.5 mm, and the arrangement of the card slot matches the arrangement shape of the plurality of truss units; (3) The plane where the truss-type air-cooling 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 area of ​​the heat exchange surface is matched, that is, the length and width are both 230×165mm; (4) Arrange a thermocouple at the soft-pack battery near the phase change material heat exchange plane layer. The thermocouple arrangement position is as follows: Fig.10 As shown, the composite phase change material coupled air-cooled battery is discharged using a 2C discharge rate.

[0046] After the discharge test analysis, the temperature data curve is as follows Fig.12 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 44.9°C and the battery temperature difference within 0.7°C.

[0047] 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.

[0048] 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 composite phase change material coupled air cooling battery, characterized in that: The invention comprises a pair of soft-pack batteries (1) with a thickness of 6 to 15 mm, at least one truss-type air-cooling plane layer (3) for convective heat exchange and ventilation between the batteries is provided between the pair of soft-pack batteries (1), and the thickness of the truss-type air-cooling plane layer (3) is 2.5 to 6 mm; and a pair of phase change material heat exchange plane layers (2) are also provided between the truss-type air-cooling plane layer (3) and the pair of soft-pack batteries (1); The truss-type air-cooled plane layer (3) is composed of a plurality of truss monomers (31) arranged in a matrix; the phase change material heat exchange plane layer (2) is composed of a sealed shell (21) 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 (2) is 2 to 10 mm, and the composite phase change material is paraffin and thermoplastic rubber material in a mass ratio of 4 to 6:4 to 6; At the same time, the plane where the truss-type air-cooling plane layer (3), the phase change material heat exchange plane layer (2) 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 composite phase change material coupled air-cooled battery according to claim 1, characterized in that: The phase change material heat exchange plane layer (2) further comprises at least one truss plane layer (22) disposed in the sealed shell cavity, the truss plane layer (22) having the same structure as the truss type air cooling plane layer (3), and the composite phase change material having a density of 0.9 to 0.928 g / cm3 is filled in the truss plane layer (22) and fills the sealed shell cavity.

3. The composite phase change material coupled air-cooled battery according to claim 2, characterized in that: The preparation process of the phase change material heat exchange plane layer (2) is as follows: First, heat the temperature of paraffin to above 80°C to completely melt the paraffin; Next, liquid phase paraffin and powdered thermoplastic rubber are stirred and mixed at a mass ratio of 4-6:4-6, and stirred for at least 30 minutes at a temperature above 80° C. to uniformly mix the thermoplastic rubber in the paraffin, thereby obtaining a liquid phase composite phase change material of paraffin / thermoplastic rubber; Then, the truss plane layer (22) is placed in the cavity of the sealed housing, and then the liquid paraffin / thermoplastic rubber composite phase change material is injected into the cavity of the sealed housing; The sealed shell containing the composite phase change material of liquid paraffin / thermoplastic rubber and the truss plane layer is placed in a vacuum box. 6 The vacuum pressure of Pa discharges the bubbles in the composite phase change material; Finally, the shell is naturally cooled to room temperature, excess solid composite phase change material is removed, and the shell is sealed to obtain a phase change material heat exchange plane layer (2) of paraffin / thermoplastic rubber / truss plane layer.

4. The composite phase change material coupled air-cooled battery according to claim 1, characterized in that: The truss monomer (31) comprises: an octahedral central structure (311) constructed by 36 truss rods and eight tetrahedral structures (312) outside the octahedral central structure (311), wherein one tetrahedral structure (312) is constructed by 6 truss rods; The three truss connection points of each face of the octahedral central structure (311) are the three truss end points of a tetrahedral structure (312), and the truss connection points of the tetrahedral structure (312) are the end points of the outer contour of the truss monomer (31), so that the outer contour of the truss monomer (31) forms a cube structure; then, two truss monomers (31) are connected to each other through the end points of the outer contour of the truss monomer, forming a truss-type air-cooled plane layer (3); Then, the matrix arrangement of the multiple truss monomers (31) 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 monomers perpendicular to their horizontal direction, d is the truss diameter of the truss monomers, L is the length of the truss rod of the octahedral central structure, β is the angle between the truss rod of the octahedral central structure (311) and the vertical direction, then the setting distance between two truss monomers (31) in the horizontal direction and the span direction is: ， 。 5. The composite phase change material coupled air cooling battery according to claim 4, characterized in that: The angle β is 30 to 80°; the length of the truss rod of the octahedral central structure (311) is L, and n is the number of truss monomers arranged in the thickness direction. is the thickness of the composite phase change material layer, then ; Where n is 1 to 5.

6. The composite phase change material coupled air-cooling battery according to any one of claims 1 to 5, characterized in that: The sealing shell (21) is provided with a slot (23) for conveniently installing a plurality of the truss monomers (31); the depth of the slot (23) is half the diameter of a truss rod constituting the truss monomer (31); and the arrangement of the slot (23) matches the arrangement shape of the plurality of truss monomers.

7. A battery pack composed of composite phase change material coupled air-cooled batteries, characterized in that: The battery pack comprises at least three soft-pack batteries (1), a pair of phase change material plane layers (3) are provided between every two of the soft-pack batteries (1), and a truss-type air-cooling plane layer (3) is sandwiched between the phase change material plane layers (3).

8. A thermal management method for a battery using the composite phase change material coupled with air cooling as claimed in claims 1, 3-6, characterized in that: The soft-pack battery (1) will continuously generate heat during operation, and the phase change material plane layer (2) will continuously absorb the heat, causing the temperature of the phase change material plane layer (2) to gradually rise; When the temperature of the phase change material plane layer (2) 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 the state of the phase change material gradually changes from solid to liquid. At the same time, during the heat absorption process, the phase change material plane layer (2) continuously releases heat (5), which is continuously transferred to the truss-type air-cooled plane layer (3) with a relatively low temperature. The heat (5) is cooled by air heat exchange in the truss-type air-cooled plane layer (3), thereby realizing a composite heat exchange of phase change and air cooling for the soft-pack battery (1), and effectively controlling the operating temperature of the soft-pack battery (1) to be less than or equal to 45°C.

9. The thermal management method of a battery according to claim 8, characterized in that: When heat (5) flows from the phase change material plane layer (2) into the truss-type air-cooled plane layer (3), the cold air flow (4) flowing into the truss monomer (31) contacts the surface of the truss monomer (31) having the heat (5). At this time, the ratio of the diameter d to the height h of the truss monomer (31) in the truss-type air-cooled plane layer (3) varies in the range of 0.20 to 0.24, so as to increase the area of ​​the truss monomer (31) contacting the heat (5), thereby increasing the temperature of the truss monomer (31) in the truss-type air-cooled plane layer (3), and finally transferring the heat from the surface of the truss monomer (31) to the cold air flow (4); After the cold air flow (4) passing through the surface of the truss monomer (31) is heated, the temperature of the cold air flow (4) increases, the density decreases, and the air expands. At this time, the porosity formed by the truss monomer (31) varies in the range of 0.887 to 0.843, so as to increase the flow resistance in the channel formed by the truss monomer (31), and make the cold air flow (4) have a velocity gradient and a pressure gradient after passing through the truss monomer (31). After the cold air flow (6) is heated, a longitudinal vortex (7) in which fluid micro-clusters rotate is formed in the pores formed by the truss monomer (31), and the vortex rotation axis of the longitudinal vortex (7) is parallel to the flow direction of the air flow, thereby promoting the air flow rate and improving the heat exchange efficiency.

10. A thermal management method for a battery using the composite phase change material coupled with air cooling as claimed in claims 2, 3-6, 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 (2) 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 in the truss plane layer (22) inside the phase change material heat exchange plane layer (2) varies in the range of 0.08 to 0.174; the porosity of the formed truss plane layer (22) 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 plane layer (2) 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 (22) 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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