High-safety battery thermal management system giving consideration to high-temperature heat dissipation, low-temperature heating and thermal spread suppression

Abstract

The invention discloses a high-safety battery heat management system with high-temperature heat dissipation, low-temperature heating and heat spread suppression considered. The high-safety battery heat management system comprises a power battery pack and a heat management system, the power battery pack comprises a battery pack consisting of a plurality of square battery cells and a large-scale battery module formed by connecting the battery packs in parallel; a plurality of battery cells are connected in series in each battery pack, the battery packs are vertically arranged, the large-scale battery module is formed by horizontally arranging the battery packs, and each battery pack comprises equal or unequal battery cells; the thermal management system comprises a flexible flame-retardant phase-change material, a liquid cooling plate, a heating film and aerogel; a part of side surfaces between the battery cells are uniformly filled with a flexible flame-retardant phase-change material, the other side surfaces are wrapped by aerogel, the bottoms of the battery cells are connected with an integrated unit of a heating film and a liquid cooling plate, and the heating film is positioned at the positions of the battery cells for heating; the battery pack is cooled through water cooling and phase change latent heat; heating the battery pack through a heating film at the bottom of the battery cell; and the thermal runaway of the battery is inhibited through the combination of the flexible flame-retardant phase-change material and the aerogel.

Description

Technical Field

[0001] The present invention belongs to the field of battery thermal management, and in particular relates to a high-safety battery thermal management system that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression. Background Art

[0002] Compared with traditional fuel vehicles, electric vehicles have the advantages of zero emissions, low noise, energy saving and environmental protection, and have become one of the main development directions of the automotive industry in the future. However, the thermal safety of electric vehicles has become a bottleneck problem restricting the development of the entire industry, especially safety accidents caused by thermal runaway. The power battery, known as the heart of the electric vehicle, its performance will directly affect the vehicle's driving range, operating safety, etc. Temperature is the key to directly affecting the thermal safety of the power battery. Too high or too low temperature will cause a certain degree of decline and decay in battery performance, especially under different types of abuse, the risk of thermal runaway is higher. During the entire life cycle, it is crucial to control the power battery within a reasonable operating temperature range and maintain good temperature consistency. Therefore, thermal management of power batteries is very necessary and is considered to be one of the key technologies of electric vehicles. The main functions of the battery thermal management system are as follows: (1) Control the maximum temperature inside the battery pack; (2) Balance the temperature consistency within the battery module; (3) Rapid and balanced heating under low temperature conditions; (4) Ensure battery safety.

[0003] In recent years, the high-temperature heat dissipation systems of electric vehicle batteries mainly include air cooling systems, liquid cooling systems and PCM cooling systems. The low cooling efficiency of air cooling cannot match the growing large-scale power battery system, and the temperature consistency is poor. Phase change material cooling, as a new heat dissipation method, utilizes the latent heat in the phase change process of phase change materials to absorb the heat generated by the battery pack to achieve the advantages of uniform temperature and temperature control, and has high heat dissipation efficiency. The liquid cooling system uses liquid as the cooling medium and takes away the heat generated by the battery through convection heat transfer. The liquid cooling medium has a high heat transfer coefficient, large specific heat capacity, and fast cooling speed, which can effectively reduce the maximum temperature of the battery and improve the uniformity of temperature distribution. At the same time, the structure of the liquid cooling system is relatively compact.

[0004] Phase change materials and liquid cooling technology each have their own advantages for high-temperature heat dissipation. The effective combination of the two allows phase change materials to take on some of the functions of liquid cooling plates, reducing the overall energy consumption of the system, thereby achieving the dual advantages of excellent temperature uniformity and temperature control, and ultimately achieving better heat dissipation efficiency. Compared with high-temperature heat dissipation, low-temperature heating of power batteries has not received as much attention as high-temperature heat dissipation. Low-temperature heating mainly includes external heating and internal heating. Considering the mechanism of internal heating of the battery's internal performance degradation and aging, this is a factor we must consider, and external heating has great advantages. At the same time, electric vehicles may cause thermal runaway under abuse conditions such as overcharging, over-discharging, mechanical damage or external heating, which not only affects a single battery cell, but may also quickly spread to the entire battery pack, causing catastrophic consequences. An effective thermal runaway suppression system is very important.

[0005] Heat dissipation has always been the main research direction of phase change materials and liquid cooling coupling systems. There is still a lack of research on battery heating and flame retardancy. It is crucial to integrate the main functions that the battery system should have. While the battery should dissipate heat, it should also have the functions of heating and preventing the spread of thermal runaway, reduce the attenuation of battery performance in low temperature environments, and increase effective control of the battery when thermal runaway occurs.

[0006] The team has rich research experience in the preparation of composite phase change materials and their application in the field of battery thermal management, which is also one of its outstanding advantages. In particular, organic phase change materials represented by paraffin have overcome the above-mentioned technical difficulties of low mechanical strength, low thermal conductivity, easy leakage, flame retardancy and electrical insulation through material modification. At the same time, liquid cooling plates and heating film products are also outstanding advantages of the team. Summary of the invention

[0007] The purpose of the present invention is to provide a high-safety battery thermal management system that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, so as to solve the three major functions of high-temperature heat dissipation, low-temperature heating and thermal runaway spread suppression of the battery.

[0008] The present invention provides a high-safety battery thermal management system that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, including a power battery pack and a thermal management system; the power battery pack includes a battery pack composed of a plurality of square battery cells and a large-scale battery module composed of battery packs connected in parallel; a plurality of battery cells are connected in series in each of the battery packs, the battery packs are arranged vertically, and the large-scale battery module is formed by horizontally arranging the battery packs, and each of the battery packs includes an equal or unequal number of the battery cells; the thermal management system includes a flexible flame-retardant phase change material, a liquid cooling plate, a heating film, and an aerogel; the flexible flame-retardant phase change material is evenly filled on part of the side surfaces between the battery cells, and the remaining side surfaces are wrapped by the aerogel, the bottom of the battery cell is connected to an integrated unit of the heating film and the liquid cooling plate, and the heating film is located at the position of the battery cell for heating; the battery pack is cooled by water cooling and phase change latent heat; the battery pack is heated by the heating film at the bottom of the battery cell; and the thermal runaway of the battery is suppressed by the combination of the flexible flame-retardant phase change material and the aerogel.

[0009] Furthermore, the integrated unit of the heating film and the liquid cooling plate is formed by adhering the heating film and the liquid cooling plate via an adhesive film, and the heating film and the liquid cooling plate are pressed into one by means of flat plate hot pressing.

[0010] Furthermore, the heating position of the heating film is optimized, and only the battery cell position is retained for heating.

[0011] Furthermore, a thermal conductive pad is provided between the bottom of the battery core and the bottom of the flexible flame-retardant phase change material and the integrated unit of the heating film and the liquid cooling plate.

[0012] Furthermore, a first gap is left between the battery cells in the vertical direction, and the flexible flame-retardant phase change material is placed in the first gap.

[0013] Furthermore, the thickness of the first gap is controlled by a minimum thickness required to suppress the spread of thermal runaway when thermal runaway occurs in the battery cell.

[0014] Furthermore, the flexible flame-retardant phase change material is made by mixing 70% paraffin, 20% a mixture of hydroxystyrene-butylene glycol block copolymer and aluminum hydroxide, and 10% a flexible thermal conductive material.

[0015] Furthermore, the preparation method of the flexible flame-retardant phase change material is to heat the paraffin and the flexible material to 180°C for 2 hours, and then start the agitator and stir at a speed of 500r / min until they are dissolved until they are molten gel, add a variety of specific combustion aids and stir for another 0.5 hours, and then add thermal conductive materials in small amounts multiple times.

[0016] Furthermore, a second gap is left between the battery groups in the horizontal direction, and the aerogel is placed in the second gap.

[0017] Furthermore, the thickness of the second gap is controlled by a minimum thickness that satisfies the requirement that the maximum temperature of a side of an adjacent battery pack that is in close contact with the aerogel does not reach a runaway temperature when a thermal runaway occurs in the battery cell.

[0018] The present invention has good temperature uniformity and temperature control capabilities. In terms of cooling: the flexible flame-retardant phase change material evenly absorbs the heat generated by the battery cell, and then the heat is taken away by the liquid cooling plate at the bottom, so the effectiveness of the phase change material function is always guaranteed. At the same time, the heat generated by the battery cell can also be directly taken away by the liquid cooling plate, and the heat dissipation effect is better. In terms of heating: the heat is transferred to the battery cell through the heating film at the bottom, and the flexible flame-retardant phase change material also stores the heat generated after work through latent heat, which can maintain the temperature of the battery for a longer time and save power consumption.

[0019] The present invention has the advantage of excellent thermal runaway suppression. When thermal runaway occurs in the battery cell, the temperature rises rapidly, and the heat is quickly absorbed through the phase change of the flexible flame-retardant phase change material. The parameters and thickness of the flexible flame-retardant phase change material are optimized, and the liquid cooling plate cooperates with it to dissipate heat. When thermal runaway occurs in a certain battery cell, the spread of the thermal runaway to the adjacent battery cells in the vertical direction can be controlled. The spread of the thermal runaway of the battery pack in the horizontal direction can be controlled by the flexible flame-retardant phase change material and the aerogel, thereby ensuring the overall safety.

[0020] The present invention has a high degree of integration capability. The flexible flame-retardant phase-change material has the largest contact surface with the battery cell, ensuring good heat dissipation, heating and flame retardancy. The aerogel ensures the horizontal side surface while allowing adjacent battery packs to fit closely, ensuring the volume utilization of the overall battery. The bottom heating film and liquid cooling plate are integrated into a unit, reducing the number of parts and solving the problem of the placement of the heating film. At the same time, the high elasticity and pressure resistance of the flexible flame-retardant phase-change material can allow the flexible flame-retardant phase-change material to fit closely to other parts to fill the gap, and avoid volume changes during phase change that damage the battery cell.

[0021] The present invention rationally couples the flexible flame-retardant phase change material with the liquid cooling plate cooling. The battery module has a compact structure and complete functions, which can meet all the main functions that the battery thermal management system needs to achieve: (1) Control the maximum temperature inside the battery pack; (2) Balance the temperature consistency within the battery module; (3) Rapid and balanced heating under low temperature conditions; (4) Ensure the safety of the battery. The system runs stably and reliably, and the battery module is large, which can meet the needs of electric vehicle batteries and has broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods and technical solutions of the present invention, the following briefly introduces the drawings required for the specific implementation methods and technical descriptions.

[0023] Figure 1 It is a three-dimensional diagram of a high-safety battery thermal management system of the present invention that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression.

[0024] Figure 2 For attachment Figure 1 A three-dimensional exploded view of a high-safety battery thermal management system that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression is shown.

[0025] Figure 3 For attachment Figure 1 A top view of a high-safety battery thermal management system that takes into account high-temperature heat dissipation, low-temperature heating, and heat spread suppression is shown.

[0026] Figure 4 For attachment Figure 1 A front view of a high-safety battery thermal management system that takes into account high-temperature heat dissipation, low-temperature heating, and heat spread suppression is shown.

[0027] Figure 5 For attachment Figure 1 A side view of a high-safety battery thermal management system that takes into account high-temperature heat dissipation, low-temperature heating, and heat spread suppression is shown.

[0028] In the figure: 1-battery cell; 2-battery pack; 3-flexible flame-retardant phase change material; 4-first gap; 5-aerogel; 6-second gap; 7-thermal pad; 8-integrated unit of heating film and liquid cooling plate; 9-liquid cooling plate; 10-heating film; 11-adhesive film; 12-hollow tube. DETAILED DESCRIPTION

[0029] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. The described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In addition, the implementation methods of the present invention are not limited to this. For unspecified process parameters, conventional techniques can be referred to.

[0030] See also Figure 1-Figure 5The present invention provides a high-safety composite battery thermal management system, comprising a plurality of battery packs 2, each battery pack 2 being composed of an equal number of battery cells 1, a flexible flame-retardant phase change material 3 being uniformly filled in a first gap 4 between adjacent battery cells 1, the flexible flame-retardant phase change material 3 being able to cool and heat the battery cell 1 by absorbing and releasing heat during phase change, an aerogel 5 being uniformly filled in a second gap 6 between adjacent battery packs 2, the aerogel 5 being a flame-retardant material being able to insulate heat, a thermal pad 7 being provided between the bottom of the battery cell 1 and the bottom of the flexible flame-retardant phase change material 3 and the integrated unit 8 of the heating film and the liquid cooling plate, and the bottom of the battery cell 1, the bottom of the flexible flame-retardant phase change material 3 and the bottom of the aerogel 5 being all in close contact with the top of the thermal pad 7, the bottom of the thermal pad 7 being in close contact with the integrated unit 8 of the heating film and the liquid cooling plate, the thermal pad 7 performing heat exchange between the heat change generated when the integrated unit 8 of the heating film and the liquid cooling plate is working and the battery cell 1 and the flexible flame-retardant phase change material 3, and the outer side of the battery pack 2 being sealed by a hollow plate 12.

[0031] The flexible flame-retardant phase change material 3 in the present invention is composed of 70% paraffin wax, 20% 20% hydroxystyrene-butylene block copolymer and aluminum hydroxide mixture, and 10% flexible thermal conductive material. The paraffin wax and the flexible material are heated to 180°C for 2 hours, and then the agitator is turned on and stirred at a speed of 500r / min until it is dissolved to a molten gel state, and a variety of specific combustion aids are added and stirred for 0.5 hours, and then a small amount of thermal conductive material is added multiple times to obtain a flexible flame-retardant phase change material 3. After being heated to completely melt, the flexible flame-retardant phase change material 3 is injected into the first gap 4 respectively and strictly sealed. The integrated unit 8 of the heating film and the liquid cooling plate is formed by pasting the liquid cooling plate 9 and the heating film 10 through the adhesive film 11, and then the heating film 10 and the liquid cooling plate 9 are pressed into one by flat hot pressing, and the heat dissipation of the liquid cooling plate 9 and the heating of the heating film 10 are verified, and the comparison is slightly different from the original working effect.

[0032] Flexible flame-retardant phase change material 3 not only has excellent flame-retardant properties, but also has high elasticity, compression resistance and aging resistance. The flame-retardant property can inhibit combustion when the battery has thermal runaway, and the flexible property also has the property of not squeezing the battery cell due to volume changes during normal operation.

[0033] Working process of the present invention: High-temperature heat dissipation: When the battery pack 2 is working, heat is generated, and the temperature rises and needs to be dissipated. When the temperature of the battery cell 1 is lower than the melting point of the flexible flame-retardant phase change material 3, the battery cell 1 directly transfers the heat to the liquid cooling plate 9 to take away the heat. At this time, the liquid cooling flow rate is not easy to be too high; when the temperature of the battery cell 1 is higher than the melting point of the flexible flame-retardant phase change material 3, the battery cell 1 takes away the heat through the liquid cooling plate 9, and at the same time, the battery cell 1 transfers heat to the flexible flame-retardant phase change material 3. The flexible flame-retardant phase change material 3 begins to melt and absorbs heat through latent heat, and then transfers the heat to the liquid cooling plate 9 to take away the heat. At this time, the flow rate needs to be increased to meet the cooling requirements.

[0034] Low-temperature heating: When the ambient temperature is low, the battery pack 2 needs to be heated. The heating film 10 at the bottom heats and transfers heat to the battery cell 1. The heat generated by the battery pack 2 after operation is stored in the flexible flame-retardant phase change material 3 through latent heat. When the vehicle is parked for a short time, the temperature of the battery pack 2 is maintained for a longer time, saving power consumption.

[0035] Thermal runaway spread suppression: When thermal runaway occurs in the battery cell 1, the flame retardant properties of the flexible flame retardant phase change material 3 are used to prevent combustion, and the flexible flame retardant phase change material 3 and the liquid cooling plate 9 quickly exchange heat to ensure that the maximum temperature of the connected battery cells 1 is below the temperature that causes thermal runaway, thereby controlling the spread of thermal runaway; the flame retardant material aerogel 5 is used to control the adjacent battery packs 2.

[0036] As described above, the present invention has good temperature uniformity and temperature control capabilities. In terms of cooling: the flexible flame-retardant phase change material 3 evenly absorbs the heat generated by the battery cell 1, and then the heat is taken away by the liquid cooling plate 9 at the bottom, so that the effectiveness of the function of the flexible flame-retardant phase change material 3 is always guaranteed. At the same time, the heat generated by the battery cell 1 can also be directly taken away by the liquid cooling plate 9, and the heat dissipation effect is better; in terms of heating: the heat is transferred to the battery cell 1 through the heating film 10 at the bottom, and the flexible flame-retardant phase change material 3 also stores the heat generated after work through latent heat, which can maintain the temperature of the battery for a longer time and save power consumption.

[0037] The present invention has the advantage of excellent thermal runaway suppression. When thermal runaway occurs in the battery cell 1, the temperature rises rapidly, and the heat is quickly absorbed through the phase change of the flexible flame-retardant phase change material 3. The parameters and thickness of the flexible flame-retardant phase change material 3 are optimized, and the liquid cooling plate 9 cooperates with the flexible flame-retardant phase change material 3 to dissipate heat. When thermal runaway occurs in a certain battery cell 1, the spread of the thermal runaway to the adjacent battery cell 1 in the vertical direction can be controlled. The spread of the thermal runaway of the battery pack 2 in the horizontal direction can be controlled by the flexible flame-retardant phase change material 3 and the aerogel 5 to ensure overall safety.

[0038] The present invention has a high degree of integration capability. The flexible flame-retardant phase-change material 3 and the battery cell 1 have the largest contact surface, ensuring good heat dissipation, heating and flame retardancy. The aerogel 5 ensures the horizontal side and can make the adjacent battery pack 2 close together, ensuring the volume utilization of the overall battery. The heating film and liquid cooling plate integrated unit 8 at the bottom reduce the number of parts and solve the problem of the placement of the heating film 10. At the same time, the high elasticity and pressure resistance of the flexible flame-retardant phase-change material 3 can make the flexible flame-retardant phase-change material 3 close to other parts to fill the gap, and avoid the volume change during phase change to crush the battery cell 1.

[0039] The present invention rationally couples the flexible flame-retardant phase change material 3 and the liquid cooling plate 9 together for cooling. The battery module has a compact structure and complete functions, which can meet all the main functions that the battery thermal management system needs to achieve: (1) controlling the maximum temperature inside the battery pack; (2) balancing the temperature consistency within the battery module; (3) rapid and balanced heating under low temperature conditions; (4) ensuring the safety of the battery. The system operates stably and reliably, and the battery module is large, which can meet the needs of electric vehicle batteries and has broad market prospects.

[0040] The above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A high-safety battery thermal management system that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, characterized in that: It comprises a power battery pack and a thermal management system; the power battery pack comprises a battery pack composed of several square battery cells and a large-scale battery module composed of battery packs connected in parallel; several battery cells are connected in series in each battery pack, the battery packs are arranged vertically, and the large-scale battery module is formed by arranging the battery packs horizontally, and each battery pack comprises an equal or unequal number of battery cells; the thermal management system comprises a flexible flame-retardant phase change material, a liquid cooling plate, a heating film, and an aerogel; part of the side surfaces between the battery cells are uniformly filled with the flexible flame-retardant phase change material, and the remaining side surfaces are wrapped by the aerogel, the bottom of the battery cell is connected to the integrated unit of the heating film and the liquid cooling plate, and the heating film is located at the battery cell position for heating; the battery pack is cooled by water cooling and phase change latent heat; the battery pack is heated by the heating film at the bottom of the battery cell; the thermal runaway of the battery is suppressed by the combination of the flexible flame-retardant phase change material and the aerogel.

2. The high-safety battery thermal management system according to claim 1 that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, characterized in that: The integrated unit of the heating film and the liquid cooling plate is formed by adhering the heating film and the liquid cooling plate via an adhesive film, and the heating film and the liquid cooling plate are pressed into one by means of flat plate hot pressing.

3. The high-safety battery thermal management system according to claim 1 that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, characterized in that: The heating position of the heating film is optimized, and only the battery cell position is retained for heating.

4. The high-safety battery thermal management system according to claim 1 that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, characterized in that: A thermal pad is provided between the bottom of the battery core, the bottom of the flexible flame-retardant phase change material, and the integrated unit of the heating film and the liquid cooling plate.

5. The high-safety battery thermal management system according to claim 1 that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, characterized in that: A first gap is left between the battery cells in the vertical direction, and the flexible flame-retardant phase change material is placed in the first gap.

6. The high-safety battery thermal management system according to claim 5 that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, characterized in that: The thickness of the first gap is controlled by a minimum thickness required to suppress the spread of thermal runaway when thermal runaway occurs in the battery cell.

7. The high-safety battery thermal management system according to claim 1 that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, characterized in that: The flexible flame-retardant phase-change material is prepared by mixing 70% of paraffin wax, 20% of a mixture of hydroxystyrene-butylene copolymer and aluminum hydroxide, and 10% of a flexible thermal conductive material.

8. The high-safety battery thermal management system according to claim 7 that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, characterized in that: The preparation method of the flexible flame-retardant phase change material is to heat paraffin and flexible material to 180°C for 2 hours, turn on the stirrer and stir at a speed of 500r / min until they are dissolved until they are molten gel, add a variety of specific combustion aids and stir for another 0.5 hours, and then add thermal conductive material in small amounts multiple times.

9. The high-safety battery thermal management system according to claim 1 that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, characterized in that: A second gap is left between the battery groups in the horizontal direction, and the aerogel is placed in the second gap.

10. The high-safety battery thermal management system according to claim 9 that takes into account high-temperature heat dissipation, low-temperature heating and heat spread suppression, characterized in that: The thickness of the second gap is controlled by a minimum thickness that satisfies the requirement that the maximum temperature of a side of an adjacent battery pack that is close to the aerogel does not reach a runaway temperature when a thermal runaway occurs in the battery cell.

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