A single-motor-linked active phase change lithium battery full-temperature-range thermal management system

Abstract

This invention belongs to the field of thermal management technology for power batteries in new energy vehicles, and relates to a single-motor linked active phase change lithium battery full-temperature-range thermal management system, comprising: a composite phase change material, a thermally conductive aluminum rod, a cooling fan, and a bidirectional drive motor; the composite phase change material is attached to the surface of the lithium-ion battery, and the cooling fan's heat dissipation direction is towards the lithium-ion battery; the thermally conductive aluminum rod is inserted into the composite phase change material, and the bidirectional drive motor is poweredly connected to the cooling fan and the thermally conductive aluminum rod respectively; the composite phase change material is composed of the following components in parts by weight, which are then impregnated in foamed graphite with a porosity of 78% to 82%: polyethylene glycol 1.6 to 2.0 parts, calcium chloride 8.7 to 9.1 parts, and calcium chloride hexahydrate 88 to 9 parts; this invention integrates high-temperature heat dissipation and low-temperature active heating modules using a unidirectional clutch structure, transforming passive heat storage into active intelligent thermal management, effectively reducing the system volume, and achieving efficient and safe thermal management of the battery across the entire temperature range.

Description

Technical Field

[0001] This invention belongs to the field of thermal management technology for power batteries in new energy vehicles, specifically relating to a full-temperature-range thermal management system for a single-motor-linked active phase-change lithium battery. Background Technology

[0002] In recent years, with the rapid development of the new energy vehicle industry, pure electric vehicles, due to their significant advantages of zero emissions and high energy efficiency, have become the core path for achieving "dual carbon" goals in the transportation sector, playing a crucial role in global energy structure adjustment and energy conservation and emission reduction. Lithium-ion batteries, with their outstanding characteristics of high energy density, long cycle life, and low self-discharge rate, have become the preferred power source for electric vehicles. Their performance, safety, and lifespan directly determine the overall quality of new energy vehicles.

[0003] However, lithium-ion batteries are extremely sensitive to ambient temperature, with their optimal operating temperature range typically between 20°C and 40°C. Temperature deviations from this range severely impact battery performance and safety. At high temperatures, the internal chemical reaction rate accelerates, increasing the risk of thermal runaway and potentially leading to fires, explosions, and other safety incidents, threatening the lives and property of occupants. At low temperatures, the electrolyte viscosity increases, the ion solid-phase diffusion rate slows, and the charge transfer impedance increases sharply, resulting in a drastic drop in battery discharge capacity and significantly reduced charge-discharge efficiency, failing to meet the normal operating requirements of electric vehicles. Furthermore, low-temperature charging easily triggers lithium plating, where growing lithium dendrites can puncture the battery separator, causing internal short circuits and irreversible damage, further shortening battery life and creating safety hazards. Therefore, developing a full-temperature-range, efficient, and stable battery thermal management system to achieve precise temperature control under different environments is crucial for ensuring the safe and reliable operation of lithium-ion batteries and promoting the high-quality development of the new energy vehicle industry.

[0004] Currently, traditional lithium-ion battery thermal management systems primarily focus on cooling and heat dissipation under high-temperature conditions, paying relatively little attention to heating and insulation in low-temperature environments, making it difficult to meet the temperature control requirements across the entire temperature range. Existing low-temperature heating technologies are mainly divided into two categories: internal heating and external heating. While internal heating has the advantage of rapid heating, its control strategy is complex, hardware costs are high, and the heating current directly acts on the battery cell, which can easily accelerate internal battery aging and even cause safety risks such as localized overheating. Traditional external heating methods generally suffer from low energy efficiency, large system size, and uneven temperature distribution, failing to achieve rapid and uniform battery heating and making it difficult to adapt to the lightweight and miniaturized design requirements of new energy vehicles.

[0005] Phase change materials (PCMs), with their unique characteristics of high heat storage density and constant temperature during phase change, can achieve efficient heat storage and release. In recent years, they have become a research hotspot in the field of battery external thermal management, providing a new technical path for solving the problem of temperature control across the entire temperature range. PCMs can be divided into two main categories based on their main components: organic PCMs and inorganic PCMs. Among them, inorganic hydrated salt PCMs and organic PCMs are currently the two most widely used PCMs in the field of power battery thermal management. However, both have significant technical bottlenecks in practical applications, limiting their large-scale application in power battery thermal management.

[0006] Specifically, while organic phase change materials (PCCs) offer advantages such as low phase separation and good stability, their relatively low latent heat of phase change, susceptibility to leakage, and typically extremely low thermal conductivity severely limit their thermal response rate, hindering rapid temperature control in batteries. Inorganic hydrated salt PCCs, on the other hand, boast high latent heat of phase change, readily available raw materials, and low cost. Their phase change enthalpy is significantly higher than that of traditional organic PCCs, making them more suitable for the high-efficiency thermal management requirements of power batteries. However, these materials generally suffer from severe supercooling and phase separation issues, and their low thermal conductivity further impacts their practical application. Supercooling is a key obstacle to the application of inorganic hydrated salt PCCs in low-temperature battery heating environments—under low-temperature conditions, due to supercooling, hydrated salts often fail to spontaneously crystallize and release heat at the required battery temperature, resulting in insufficient heat replenishment and hindering effective insulation and heating in low-temperature environments.

[0007] To address the aforementioned issues, current industry research on the modification of hydrated salt phase change materials primarily focuses on suppressing or eliminating supercooling to induce spontaneous crystallization and heat release at the target temperature. However, this modification method struggles to balance the material's supercooling characteristics with heating precision. In fact, if actively triggered crystallization of hydrated salt phase change materials could be achieved, the material's supercooling could be maintained or even increased, allowing it to trigger crystallization and release latent heat as needed at extremely low ambient temperatures. This would enable precise and rapid heating of the battery, significantly improving the efficiency of battery thermal management in low-temperature environments. Therefore, developing a novel composite phase change material that combines high thermal conductivity, high supercooling, high latent heat, and leak-proof performance has become a core requirement for overcoming current technological bottlenecks.

[0008] In addition, existing battery thermal management systems also suffer from unreasonable structural design: the cooling module and the heating module are usually designed and arranged as two independent systems. This separate design not only significantly increases the overall weight and space occupied by the battery pack, which is not in line with the development trend of lightweighting of new energy vehicles, but also leads to redundant system control logic, complex structure, increased system failure rate and maintenance cost, and at the same time, it cannot achieve efficient heat utilization.

[0009] In summary, the current field of battery thermal management urgently needs to solve two core technical challenges: First, there is a lack of composite phase change materials that combine high thermal conductivity, large subcooling, high latent heat, and leak-proof performance, making it impossible to achieve precise and rapid heating of batteries in low-temperature environments. Second, existing thermal management systems employ a discrete design, making it difficult to organically integrate high-temperature heat dissipation with low-temperature active-triggered phase change heat release, and also suffer from drawbacks such as large size, heavy weight, and complex control. Therefore, developing a full-temperature-range integrated battery thermal management solution that can solve the above technical challenges has significant practical significance and application value for promoting the development of the lithium-ion battery and new energy vehicle industries. Summary of the Invention

[0010] This invention provides the following technical solution: a single-motor-linked active phase-change lithium battery full-temperature-range thermal management system, comprising: Composite phase change materials are used to absorb heat during solid-liquid phase transition at high temperatures in lithium-ion batteries, and to release heat during liquid-solid phase transition at low temperatures in lithium-ion batteries.

[0011] The thermally conductive aluminum rod is used to perform axial linear reciprocating motion within the composite phase change material. At low temperatures, it triggers the exothermic crystallization of the composite phase change material, and at high temperatures, it assists in conducting the heat absorbed by the composite phase change material.

[0012] Cooling fans are used to cool lithium-ion batteries by air cooling.

[0013] A bidirectional drive motor is used to provide torque to the cooling fan in both forward and reverse directions, or to convert torque into reciprocating power to provide traction force for the heat-conducting aluminum rod via a crank-connecting rod mechanism. The bidirectional drive motor's forward and reverse rotation enables switching control between forced air cooling and actively triggered phase-change heating from a single power source.

[0014] The composite phase change material is attached to the surface of the lithium-ion battery, and the cooling fan is directed towards the lithium-ion battery. A thermally conductive aluminum rod is inserted into the composite phase change material, and a bidirectional drive motor is connected to both the cooling fan and the thermally conductive aluminum rod.

[0015] The composite phase change material is composed of the following components in parts by weight, which are then impregnated in foamed graphite with a porosity of 78% to 82%: 1.6 to 2.0 parts of polyethylene glycol, 8.7 to 9.1 parts of calcium chloride, and 88 to 9 parts of calcium chloride hexahydrate.

[0016] Preferably, the preparation of the composite phase change material includes the following steps: S1. Stir polyethylene glycol until the gel-like solid is completely dissolved into a liquid.

[0017] S2. Weigh calcium chloride and calcium chloride hexahydrate, grind them, and mix them with the polyethylene glycol solution obtained in step S1. Stir magnetically in a water bath at 42-48°C for no less than 30 minutes until the solid particles are completely dissolved to obtain the modified phase change material. The mass ratio of calcium chloride to calcium chloride hexahydrate is 1:5-15; the mass ratio of polyethylene glycol to calcium chloride is 1:3-6.

[0018] S3. The modified phase change material and foamed graphite are vacuum impregnated in an environment of 58-62℃ and -0.1 MPa for no less than 1 h to obtain a composite phase change material.

[0019] Preferably, the lithium-ion battery surface is provided with a thermocouple for real-time monitoring of the lithium-ion battery temperature; the thermocouple is electrically connected to a temperature controller, the temperature controller is electrically connected to a motor controller, and the motor controller is electrically connected to a bidirectional drive motor.

[0020] The output shaft torque of the bidirectional drive motor is connected to the torque input end of the reducer. The torque output end of the reducer is connected to the rotating parts of the cooling fan and the crank-connecting rod mechanism, respectively. The cooling fan and the crank-connecting rod mechanism are respectively equipped with a first one-way bearing and a second one-way bearing with opposite driving directions, used to drive the cooling fan or the crank-connecting rod mechanism respectively when the bidirectional drive motor rotates forward and backward, without interfering with each other. The translation part of the crank-connecting rod mechanism is connected to the heat-conducting aluminum rod. The main drive shaft has a first one-way bearing that locks clockwise at the end connected to the cooling fan, ensuring that the bidirectional drive motor only drives the cooling fan when rotating clockwise. The main drive shaft has a second one-way bearing that locks counterclockwise at the end connected to the crank-connecting rod crossbeam mechanism, ensuring that the bidirectional drive motor only drives the heat-conducting aluminum rod when rotating counterclockwise.

[0021] More preferably, when the composite phase change material is provided in multiple pieces, each piece of composite phase change material is matched with a set of thermally conductive aluminum rods, and the linear reciprocating motion directions of each set of thermally conductive aluminum rods are parallel to each other; the front end of each thermally conductive aluminum rod is connected to a crossbeam, and the crossbeam is connected to the translation part of the crank-connecting rod mechanism. When driven by a bidirectional drive motor, the crossbeam only moves linearly within the sliding track, thereby driving multiple thermally conductive aluminum rods to synchronously perform linear reciprocating motion.

[0022] More preferably, the thermocouples are provided in multiple locations, with the thermocouples respectively located at the center and diagonal of the surface of the lithium-ion battery.

[0023] More preferably, the control logic of the temperature controller is as follows: when the lithium-ion battery temperature is higher than 45°C, the temperature controller sends a command to the motor controller to make the bidirectional drive motor rotate clockwise, driving the cooling fan to force air cooling of the lithium-ion battery; when the lithium-ion battery temperature is in the range of 15°C to 45°C, the motor controller controls the bidirectional drive motor to stop rotating, and the composite phase change material naturally plays a role in absorbing heat, maintaining the lithium-ion battery temperature stability; when the lithium-ion battery temperature is lower than 15°C, the motor controller controls the bidirectional drive motor to rotate counterclockwise, driving the heat-conducting aluminum rod to make linear reciprocating motion in the composite phase change material through the crank-connecting rod mechanism, triggering the crystallization of the composite phase change material to release latent heat to heat the lithium-ion battery.

[0024] Preferably, the composite phase change material is composed of the following components in parts by weight, which are then impregnated in foamed graphite with a porosity of 80%: 1.8 parts polyethylene glycol, 8.9 parts calcium chloride, and 89.3 parts calcium chloride hexahydrate.

[0025] Preferably, the bidirectional drive motor, cooling fan, and drive shaft are each equipped with a support bearing housing and an end support bearing. This provides a fixed radial support point for the main drive shaft, preventing deformation of the main drive shaft and fan wobbling.

[0026] The beneficial effects of this invention are: 1. This invention features a highly integrated structure, making it easy to manufacture and maintain. It cleverly utilizes a single bidirectional drive motor combined with counter-arranged unidirectional bearings to achieve automatic switching between forward forced air cooling and reverse triggered heating from the same power source. It abandons complex and easily damaged multi-motor redundant control, as well as traditional PTC heating elements and complex cooling pipes, resulting in higher reliability and saving system space.

[0027] 2. This invention transforms passive heating into active heating, overcoming the bottleneck of low-temperature applications of inorganic phase change materials. Addressing the problem of excessive supercooling in inorganic hydrated salt phase change materials, which prevents timely heat release at low temperatures, this invention introduces a crank-slider device to drive an aluminum rod in linear reciprocating motion, thereby triggering the composite phase change material to crystallize and release heat at the desired temperature. It can actively heat the battery by breaking the supercooled state and instantly triggering crystallization and latent heat release at low temperatures through purely mechanical physical disturbance.

[0028] 3. This invention provides efficient full-temperature coverage, significantly extending battery life in extreme environments. It utilizes forced air cooling at high temperatures, passive heat storage via composite phase change materials at room temperature, and active phase change heating at extremely low temperatures. This not only efficiently utilizes the composite phase change material but also provides full-temperature thermal management for the battery, avoiding lithium plating damage during charging and discharging at low temperatures and the risk of thermal runaway at high temperatures.

[0029] 4. This invention has excellent battery temperature uniformity. The high supercooling and high latent heat of phase change materials of this invention, combined with the high thermal conductivity foam graphite skeleton, and the two aluminum rods driven by the crossbeam to perform synchronous temperature uniform disturbance, greatly improve the heat transfer rate inside the system, effectively eliminate the temperature gradient inside the battery, and ensure the temperature uniformity of the battery under complex operating conditions. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of a single-motor-linked active phase-change lithium battery full-temperature-range thermal management system according to the present invention. Figure 2 This is a comparison diagram of the latent heat of phase change and undercooling of the embodiments of the present invention and Comparative Example 1; Figure 3 This is a comparison diagram of the latent heat of phase change and undercooling between the embodiments of the present invention and Comparative Example 2; Figure 4 This is a graph showing the leakage rate over time according to an embodiment of the present invention. Figure 5 This is a control logic diagram of an embodiment of the present invention; Figure 6 This is an assembly diagram of the thermally conductive aluminum rod and the composite phase change material according to an embodiment of the present invention; Figure 7 This is a diagram showing the crank-connecting rod-beam mechanism and sliding track connection according to an embodiment of the present invention; Figure 8 This is a schematic diagram showing the distribution of thermocouples on the front and back sides of a lithium-ion battery pack according to an embodiment of the present invention. Figure 9 This is a schematic diagram of the connection between the thermocouple and the temperature controller in an embodiment of the present invention.

[0031] In the diagram, 1. Bidirectional drive motor; 2. Motor controller; 3. Reducer; 4. Temperature controller; 5. Main drive shaft; 6. Support bearing housing; 7. First one-way bearing; 8. End support bearing; 9. Cooling fan; 10. Second one-way bearing; 11. Crank-connecting rod mechanism; 12. Crossbeam; 13. Thermally conductive aluminum rod; 14. Sliding track; 15. Composite phase change material; 16. Lithium-ion battery; 17. Thermocouple. Detailed Implementation

[0032] The relevant technologies of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0033] like Figures 1-9As shown, this embodiment of a single-motor-linked active phase change lithium battery full-temperature-range thermal management system specifically includes an actively triggered composite phase change material 15, and a full-temperature-range thermal management system structure based on single-motor linkage for high-temperature heat dissipation and low-temperature active phase change triggering.

[0034] First, a composite phase change material with high thermal conductivity, high latent heat, and large supercooling is prepared, including the following steps: Stir polyethylene glycol in a beaker at a rate of 200 r / min for 10 min until the gel-like solid is completely dissolved into a liquid. Weigh calcium chloride and calcium chloride hexahydrate, grind them, mix them with polyethylene glycol solution, place them in a water bath at 45°C and stir with a magnetic stirrer at a rate of 200 r / min for 30 min until the solid particles are completely dissolved to obtain the modified phase change material. To obtain the modified phase change material with the best performance, the amount of polyethylene glycol was first fixed, and the mass ratio of calcium chloride to calcium chloride hexahydrate was investigated. After determining the optimal mass ratio of calcium chloride to calcium chloride hexahydrate, the mass ratio of calcium chloride to polyethylene glycol was then investigated based on this. After determining the final composition of the modified phase change material, in order to prevent material leakage and improve thermal conductivity, the modified phase change material with the largest latent heat of phase change and foamed graphite were vacuum impregnated for 1 h in an environment of 60℃ and -0.1 MPa to obtain composite phase change material 15.

[0035] Furthermore, the composite phase change material 15 is composed of 1.8 wt% polyethylene glycol, 8.9 wt% calcium chloride, 89.3 wt% calcium chloride hexahydrate, and foamed graphite with a porosity of 80%.

[0036] After the composite phase change material was prepared, a full-temperature thermal management system based on high-temperature heat dissipation and low-temperature active phase change triggering was designed. The system structure includes a bidirectional drive motor 1, a reduction gear, a cooling fan 9, a one-way bearing, a motor controller 2, a temperature controller 4, a lithium-ion battery 15, a crank-connecting rod mechanism 11, a sliding track, a composite phase change material with high supercooling, a thermally conductive aluminum rod 13, and a thermocouple 17.

[0037] Furthermore, there are six thermocouples 17 in total, three installed on the front battery and three installed on the back battery, respectively installed at the center and diagonal positions of the battery.

[0038] Furthermore, thermocouple 17 is connected to temperature controller 4. When the battery temperature is above 45°C, the controller sends a command to the motor controller, causing the motor to rotate clockwise, thereby driving the cooling fan to cool the battery. When the battery temperature is within the range of 15°C to 45°C, the motor controller 2 sends a command to stop the motor. When the battery temperature is below 15°C, the motor controller 2 sends a command to rotate the motor counterclockwise, thereby driving the heat-conducting aluminum rod 13 to perform linear reciprocating motion within the composite phase change material 15 through the crank-connecting rod mechanism 11, triggering the crystallization of the composite phase change material 15 to heat the battery.

[0039] Furthermore, a clockwise-locking one-way bearing is connected to the motor spindle before connecting to the fan, so that when the motor rotates clockwise, it only drives the fan to rotate; a counterclockwise-locking one-way bearing is connected to the motor spindle before connecting to the crank connecting rod crossbeam mechanism, so that when the motor rotates counterclockwise, it only drives the heat-conducting aluminum rod 13 to move.

[0040] Furthermore, support bearings and bearing seats are fixedly installed on the main drive shaft 5 near the cooling fan 9 and the crank connecting rod mechanism 11, respectively, to provide a fixed radial support fulcrum for the motor main shaft, making the shaft rotation more stable and preventing problems such as main shaft deformation and fan shaking.

[0041] Furthermore, a thermally conductive aluminum rod 13 is inserted into each composite phase change material 15, and the ends of the two thermally conductive aluminum rods 13 are connected by a crossbeam 12. The motor drives the crossbeam 12 through the crank-connecting rod mechanism 11. Under the constraint of the sliding track, the crossbeam 12 only makes linear translation, thereby simultaneously pulling the two thermally conductive aluminum rods 13 to make synchronous linear reciprocating motion without eccentric load.

[0042] Example To prepare a phase change material with the highest latent heat, the content of polyethylene glycol 600 was first fixed, and the effect of the anhydrous calcium chloride solute ratio on the latent heat of phase change was investigated to determine the optimal anhydrous calcium chloride solute ratio. Three mass ratios were investigated: Group 1: 1:5 ratio of calcium chloride to calcium chloride hexahydrate; Group 2: 1:10 ratio of calcium chloride to calcium chloride hexahydrate; Group 3: 1:15 ratio of calcium chloride to calcium chloride hexahydrate.

[0043] Based on the determined optimal anhydrous calcium chloride solute ratio, the effect of polyethylene glycol 600 solubilizer ratio on the latent heat of phase change of the phase change material was investigated to determine the optimal polyethylene glycol 600 ratio and thus the final preparation ratio. Four mass ratios were investigated: Group 4: polyethylene glycol 600 to calcium chloride mass ratio of 1:3; Group 5: polyethylene glycol 600 to calcium chloride mass ratio of 1:4; Group 6: polyethylene glycol 600 to calcium chloride mass ratio of 1:5; Group 7: polyethylene glycol 600 to calcium chloride mass ratio of 1:6.

[0044] The final modified phase change material consists of 1.8 wt% polyethylene glycol, 8.9 wt% calcium chloride, and 89.3 wt% calcium chloride hexahydrate.

[0045] The prepared optimal phase change material was vacuum impregnated with foamed graphite with a porosity of 80% at 60℃ and -0.1 MPa for 1 h to obtain a composite phase change material. A leakage test was then conducted on the composite phase change material in an oven at 40℃. Figure 4 The leakage rate of the composite phase change material over time is shown. After 24 hours in the oven, the leakage rate was only 3.71%. This is because foamed graphite, as a porous medium, can adsorb the phase change material within its porous structure through surface tension and capillary action, thus shaping the phase change material and reducing leakage during melting. The thermal conductivity of the uncomposite phase change material and the composite phase change material were compared, and the results are shown in Table 1. The thermal conductivity of the uncomposite phase change material was only 0.6 W / (m·K), while the composite phase change material has a thermal conductivity of 56 W / (m·K), an improvement of approximately 92 times. The composite phase change material not only solved the leakage problem but also significantly improved thermal conductivity. Table 1 compares the thermal conductivity of the uncomposite phase change material and the composite phase change material.

[0046]

[0047] Combination Figure 1 As shown in the attached figures, a full-temperature-range thermal management system based on single-motor linkage for high-temperature heat dissipation and low-temperature active phase change triggering is designed. The system includes: Thermocouple 17 is connected to temperature controller 4, such as Figure 5 As shown, when the temperature of the lithium-ion battery 16 is higher than 45°C, the temperature controller 4 sends a command to the motor controller 2, causing the bidirectional drive motor 1 to rotate clockwise, thereby driving the cooling fan 9 to dissipate heat and cool the battery.

[0048] Furthermore, when the battery temperature is within the range of 15℃ to 45℃, the temperature controller 4 sends a command to the motor controller 2 to stop the bidirectional drive motor 1 from rotating. When the battery temperature is below 15℃, the temperature controller 4 sends a command to the motor controller 2 to make the bidirectional drive motor 1 rotate counterclockwise, thereby driving the heat-conducting aluminum rod 13 to move linearly within the composite phase change material 15 through the crank-connecting rod-beam mechanism 11, triggering crystallization in the composite phase change material to heat the battery.

[0049] Before connecting the main drive shaft 5 to the cooling fan 9, a first one-way bearing 7 that is locked clockwise is connected to ensure that the motor only drives the fan to rotate when it rotates clockwise.

[0050] A counterclockwise locked second one-way bearing 10 is connected to the main drive shaft 5 before the crank connecting rod crossbeam mechanism 11, which ensures that the motor only drives the aluminum rod to move when it rotates counterclockwise.

[0051] Support bearing housing 6 and end support bearing 8 are installed near the fan and crank assembly, respectively. This provides a fixed fulcrum for the motor spindle, making the shaft rotate more smoothly and preventing problems such as spindle deformation and fan shaking.

[0052] Each composite phase change material 15 has a thermally conductive aluminum rod 13 inserted inside it. The two thermally conductive aluminum rods are connected by a crossbeam 12. The crossbeam is driven by a crank-connecting rod crossbeam mechanism 11. The crossbeam moves only in a straight line under the constraint of the sliding track 14, thereby simultaneously pulling the two thermally conductive aluminum rods to make synchronous linear reciprocating motion to trigger the crystallization of the composite phase change material.

[0053] Comparative Example 1 Pure calcium chloride hexahydrate was used as Comparative Example 1. The latent heat of phase change and undercooling of the phase change materials in Comparative Example 1 and the examples were compared. Figure 2 As shown, Figure 2 It can be noted that the latent heat of phase change (LCH) of the phase change material prepared in the examples is 197.14 J / g, the solidification temperature is -21.5℃, and the supercooling is 52℃. Comparative Example 1 has a LCH of 149.94 J / g, a solidification temperature of -0.5℃, and a supercooling of 30℃. Compared to Comparative Example 1, the examples show a 31.5% increase in LCH and a 73% increase in supercooling. This is because the added polyethylene glycol 600 nonionic surfactant increases the solubility of the inorganic salt, thus maintaining supercooling at low temperatures. Furthermore, the added calcium chloride dissolves in the unsaturated solution after the addition of polyethylene glycol 600, generating new hydrated salt crystals, thus increasing the LCH of the phase change material.

[0054] Comparative Example 2 Comparative Example 2: Pure calcium chloride hexahydrate and foamed graphite with a porosity of 80% were vacuum impregnated for 1 h at 60℃ and -0.1 MPa. Figure 3This is a comparison chart of the latent heat of phase change (LCH) and supercooling of the composite LCH materials in Comparative Example 2 and the Examples. It can be seen that the LCH of the composite LCH material prepared in the Examples is 135.84 J / g, the solidification temperature is 12.5℃, and the supercooling is 16.9℃. Comparative Example 2 has a LCH of 100.31 J / g, a solidification temperature of 16.3℃, and a supercooling of 13.1℃. Compared to Comparative Example 2, the Examples show a 34.4% increase in LCH and a 3.8℃ increase in supercooling. After being composited with foamed graphite, the LCH and supercooling of both the Examples and Comparative Example 2 decreased. However, the LCH and supercooling of the Examples are still greater than those of Comparative Example 2, indicating that even when composited with foamed graphite, adding polyethylene glycol 600 and calcium chloride to Comparative Example 1 to increase the LCH and supercooling is still effective.

[0055] In summary, the system structure of this invention is highly integrated, with simple control logic, low space occupancy, and purely mechanical error-proofing characteristics. It leverages the high supercooling properties of composite phase change materials to transform passive heat storage into active intelligent thermal management, effectively improving the cold start and charge / discharge performance of lithium-ion batteries in extreme low-temperature environments. Furthermore, combined with forced air cooling in high-temperature environments, it prevents battery overheating and utilizes highly thermally conductive composite phase change materials to better ensure the temperature uniformity of individual cells, enabling efficient operation across the entire temperature range. This solves the problems of space redundancy and structural complexity caused by separate cold and hot systems in existing technologies, as well as the problem that traditional inorganic phase change materials are limited by high supercooling and cannot crystallize and release heat in a timely manner at low temperatures.

[0056] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A single-motor-linked active phase-change lithium battery full-temperature-range thermal management system, characterized in that, include: Composite phase change material (15) is used to absorb heat by solid-liquid phase conversion at high temperature in lithium-ion battery (16) and to release heat by liquid-solid phase conversion at low temperature in lithium-ion battery (16). The thermally conductive aluminum rod (13) is used to perform axial linear reciprocating motion within the composite phase change material (15). At low temperatures, it triggers the crystallization and heat release of the composite phase change material (15). At high temperatures, it assists in conducting the heat absorbed by the composite phase change material (15). A cooling fan (9) is used to cool the lithium-ion battery (16) by air cooling. A bidirectional drive motor (1) is used to provide torque to the cooling fan (9) in both forward and reverse directions, or to convert the torque into reciprocating power to provide traction force to the heat-conducting aluminum rod (13) through a crank-connecting rod mechanism (11); The composite phase change material (15) is attached to the surface of the lithium-ion battery (16), and the heat dissipation direction of the cooling fan (9) is towards the lithium-ion battery (16); the thermally conductive aluminum rod (13) is inserted into the composite phase change material (15), and the bidirectional drive motor (1) is poweredly connected to the cooling fan (9) and the thermally conductive aluminum rod (13) respectively. The composite phase change material (15) is composed of the following components in parts by weight, which are then impregnated in foamed graphite with a porosity of 78% to 82%: 1.6 to 2.0 parts of polyethylene glycol, 8.7 to 9.1 parts of calcium chloride, and 88 to 9 parts of calcium chloride hexahydrate.

2. The single-motor-linked active phase-change lithium battery full-temperature-range thermal management system according to claim 1, characterized in that, The preparation of the composite phase change material (15) includes the following steps: S1. Stir polyethylene glycol until the gel-like solid is completely dissolved into a liquid; S2. Weigh calcium chloride and calcium chloride hexahydrate, grind them, and mix them with the polyethylene glycol solution obtained in step S1. Stir magnetically in a water bath at 42-48°C for no less than 30 minutes until the solid particles are completely dissolved to obtain the modified phase change material. The mass ratio of calcium chloride to calcium chloride hexahydrate is 1:5-15; the mass ratio of polyethylene glycol to calcium chloride is 1:3-6. S3. The modified phase change material and foamed graphite are vacuum impregnated in an environment of 58-62℃ and -0.1 MPa for no less than 1 hour to obtain a composite phase change material.

3. The single-motor-linked active phase-change lithium battery full-temperature-range thermal management system according to claim 1, characterized in that, The surface of the lithium-ion battery (16) is provided with a thermocouple (17) for real-time monitoring of the temperature of the lithium-ion battery (16); the thermocouple (17) is electrically connected to the temperature controller (4), the temperature controller (4) is electrically connected to the motor controller (2), and the motor controller (2) is electrically connected to the bidirectional drive motor (1). The output shaft torque of the bidirectional drive motor (1) is connected to the torque input end of the reducer (3), and the torque output end of the reducer (3) is connected to the rotating part of the cooling fan (9) and the crank-connecting rod mechanism (11) respectively. The cooling fan (9) and the crank-connecting rod mechanism (11) are respectively provided with a first one-way bearing (7) and a second one-way bearing (10) with opposite driving directions, which are used to drive the cooling fan (9) or the crank-connecting rod mechanism (11) respectively when the bidirectional drive motor (1) rotates forward and reverse, and the two do not interfere with each other. The translation part of the crank-connecting rod mechanism (11) is connected to the heat-conducting aluminum rod (13).

4. The single-motor-linked active phase-change lithium battery full-temperature-range thermal management system according to claim 3, characterized in that, When there are multiple composite phase change materials (15), each composite phase change material (15) is matched with a set of thermally conductive aluminum rods (13), and the linear reciprocating motion directions of each set of thermally conductive aluminum rods (13) are parallel to each other; the front end of each thermally conductive aluminum rod (13) is connected to a crossbeam (12), and the crossbeam (12) is connected to the translation part of the crank connecting rod mechanism (11).

5. The single-motor-linked active phase-change lithium battery full-temperature-range thermal management system according to claim 3, characterized in that, Multiple thermocouples (17) are provided, and the thermocouples (17) are respectively arranged at the center and diagonal of the surface of the lithium-ion battery (16).

6. The single-motor-linked active phase-change lithium battery full-temperature-range thermal management system according to claim 3, characterized in that, The control logic of the temperature controller (4) is as follows: when the temperature of the lithium-ion battery (16) is higher than 45°C, the temperature controller (4) sends an instruction to the motor controller (2) to make the bidirectional drive motor (1) rotate clockwise and drive the cooling fan (9) to force the lithium-ion battery (16) to cool down; when the temperature of the lithium-ion battery (16) is in the range of 15°C to 45°C, the motor controller (2) controls the bidirectional drive motor (1) to stop rotating, and the composite phase change material (15) naturally plays a heat absorption role to maintain the temperature of the lithium-ion battery (16) stable; when the temperature of the lithium-ion battery (16) is lower than 15°C, the motor controller (2) controls the bidirectional drive motor (1) to rotate counterclockwise, and drives the heat-conducting aluminum rod (13) to make linear reciprocating motion in the composite phase change material (15) through the crank connecting rod mechanism (11), triggering the crystallization of the composite phase change material (15) to release latent heat to heat the lithium-ion battery (16).

7. The single-motor-linked active phase-change lithium battery full-temperature-range thermal management system according to claim 1, characterized in that, The composite phase change material (15) is composed of the following components in parts by weight, which are then impregnated in foamed graphite with a porosity of 80%: 1.8 parts polyethylene glycol, 8.9 parts calcium chloride, and 89.3 parts calcium chloride hexahydrate.

8. The single-motor-linked active phase-change lithium battery full-temperature-range thermal management system according to claim 1, characterized in that, The bidirectional drive motor (1), cooling fan (9), and drive shaft are respectively equipped with support bearing housing (6) and end support bearing (8).

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