Lithium battery thermal management system and method

Abstract

According to the lithium battery thermal management system, a battery is placed in a first shell, and the periphery of a battery pack is filled with a first phase change material; one side of the thermoelectric device is in heat-conducting connection with the first shell; the second shell is in heat-conducting connection with the other side of the thermoelectric device, the second shell is filled with a second phase-change material, the top cover covers the second shell, the anode is connected with the positive electrode of the power supply, the cathode is connected with the negative electrode of the power supply, and the anode and the cathode are inserted into the second shell through the top cover.

Description

Technical Field

[0001] The present invention relates to the technical field of battery thermal management, and in particular to a lithium battery thermal management system and method. Background Art

[0002] As a key component in current electric vehicles, energy storage systems and other fields, the performance and service life of lithium batteries are highly dependent on the operating temperature. When lithium batteries are in a high-temperature environment, not only will the battery performance be reduced, but there is also a risk of thermal runaway; in a low-temperature environment, the capacity of lithium batteries will drop significantly, the lifespan will be shortened, and the use effect will be affected.

[0003] Traditional lithium battery thermal management systems mainly rely on heat dissipation methods such as air cooling and liquid cooling. However, these methods have significant limitations. The air cooling system depends on environmental conditions and it is difficult to maintain effective heat dissipation at extreme temperatures. The liquid cooling system is large in size and takes up a lot of space. The slow cold start speed of the battery in a low-temperature environment and high energy consumption are common disadvantages of the above two thermal management methods. At the same time, the above methods are insufficient in the accuracy of temperature control, especially in a wide temperature range, and dynamic adjustment is difficult to achieve. In addition, traditional thermal management methods also have the problem of energy waste. The waste heat of the battery cannot be effectively recovered and utilized, and low-temperature starting requires additional heating devices, which not only increases energy consumption but also reduces the energy density of the battery.

[0004] The information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the Invention

[0005] To address the shortcomings or defects of the aforementioned prior art, a lithium battery thermal management system and method are provided. Phase-change materials can absorb or release large amounts of heat at specific temperatures, thereby effectively managing battery temperature. Thermoelectric devices can actively transfer heat through the Peltier effect, enabling rapid control of battery temperature. This lithium battery thermal management system, combining thermoelectric devices with phase-change materials, overcomes the problems of low efficiency and uneven temperature when thermoelectric devices are used alone. It broadens the battery's operating temperature range, reduces thermal management energy consumption, and improves the energy density and service life of lithium batteries.

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] A lithium battery thermal management system includes:

[0008] The inner layer phase change material thermal buffer module comprises:

[0009] first shell,

[0010] A battery pack is placed in the first housing and is filled with a first phase change material;

[0011] a thermoelectric device, one side of which is thermally connected to the first housing;

[0012] At least one outer phase change material thermal storage module comprising:

[0013] The second shell is thermally connected to the other side of the thermoelectric device, and the second shell is filled with a second phase change material.

[0014] a top cover, which is provided on the second shell,

[0015] An electrically controlled triggering device comprising:

[0016] Anode, which is connected to the positive pole of the power supply,

[0017] The cathode is connected to the negative pole of the power supply, and the anode and cathode are inserted into the second shell through the top cover.

[0018] In the lithium battery thermal management system, when the battery pack is working, heat is dissipated when the battery pack temperature rises, and the first phase change material absorbs heat to reduce the temperature rise of the battery pack; when the temperature continues to rise, the heat is conducted to the first shell through the first phase change material, and then released to the second shell by the thermoelectric device, and the heat is conducted to the second phase change material through the second shell, and the second phase change material melts, converting the heat into latent heat for storage; when the battery pack finishes working and is in a shutdown state, the heat continues to be stored in the second phase change material in the form of latent heat; when the temperature of the battery pack is lower than the low temperature threshold temperature, direct current is applied to the second phase change material through the electronically controlled trigger device to release the stored latent heat, and the heat is conducted to the second shell through the second phase change material, and the thermoelectric device absorbs heat from the second shell and releases heat to the first shell, and the heat is conducted to the first phase change material and the battery pack in sequence through the first shell, thereby increasing the temperature of the battery pack.

[0019] In the lithium battery thermal management system, the second phase change material includes a hydrated salt, the phase change temperature range of which is 30-40°C, the supercooling degree is not less than 20°C, and the supercooling state can be destroyed by direct current.

[0020] In the lithium battery thermal management system, the first phase change material includes paraffin, and its phase change temperature range is 30-50°C.

[0021] In the lithium battery thermal management system, the battery positive electrode material of the battery pack includes lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide and ternary material, the battery negative electrode is carbon material, and the battery pack connection mode is series connection, parallel connection, and group series and parallel connection.

[0022] In the lithium battery thermal management system, the distance between the cathode and the anode does not exceed 3 cm.

[0023] In the lithium battery thermal management system, the anode is a silver rod with a diameter of not less than 2.5 mm, which is polished with 80, 200, 400, 600, and 800 grit sandpaper in sequence and coated with seed powder of the second phase change material, and the cathode is graphite or silver.

[0024] In the lithium battery thermal management system, the first phase change material is doped with a high thermal conductivity material to form a composite phase change material.

[0025] In the lithium battery thermal management system, the first shell and the second shell are made of aluminum.

[0026] The thermal management methods of lithium battery thermal management systems include:

[0027] Arrange a lithium battery thermal management system, with the battery pack placed in a first shell and the battery pack filled with a first phase change material; one side of the thermoelectric device is thermally connected to the first shell; multiple outer phase change material thermal storage modules surround the first shell, and a second shell is thermally connected to the other side of the thermoelectric device. The second shell is filled with a second phase change material, and the anode and cathode are inserted into the second shell through the top cover;

[0028] When the battery pack is working, heat is dissipated when the battery pack temperature rises. The first phase change material absorbs heat, reducing the temperature rise of the battery pack. When the temperature continues to rise, the heat is transferred to the first shell through the first phase change material. Then, the thermoelectric device releases heat to the second shell. The heat is transferred to the second phase change material through the second shell. The second phase change material melts and converts the heat into latent heat for storage.

[0029] When the battery pack is shut down, heat continues to be stored in the second phase change material in the form of latent heat; when the temperature of the battery pack is lower than the low-temperature threshold temperature, direct current is applied to the second phase change material through the electronically controlled trigger device to release the stored latent heat, and the heat is conducted to the second shell through the second phase change material. The thermoelectric device absorbs heat from the second shell and releases heat to the first shell. The heat is then conducted to the first phase change material and the battery pack in sequence through the first shell, thereby increasing the temperature of the battery pack.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The inner phase change material thermal buffer module of the present invention can control the battery pack temperature within a wider temperature range, reduce the temperature difference within the battery pack, extend the battery life and ensure the safe operation of the battery; the thermoelectric device can quickly respond to external dynamic instructions within 1 second, and actively transfer heat between the inner phase change material thermal buffer module and the outer phase change material heat storage module; the outer phase change material heat storage module can store the heat dissipated by the battery pack in the form of latent heat for a long time of more than 72 hours within a wider temperature range, and quickly release the stored heat after being triggered when the battery pack needs to be heated. When the battery pack is operating under high temperature conditions, the thermoelectric device regulates the transfer of heat from the battery pack and the surrounding inner layer first phase change material to the outer layer second phase change material. The outer layer second phase change material continuously absorbs the heat generated by the battery pack and stores it in the form of latent heat. For example, for 3 The 3-cell lithium-ion battery module can recycle 80% of waste heat. When the battery pack needs to start in a low-temperature environment, the outer second phase-change material undergoes a phase change and releases latent heat when triggered by a current from a trigger device. The thermoelectric device actively controls the flow of heat from the outer second phase-change material to the inner first phase-change material, achieving rapid heating of the battery pack. The energy used to heat the battery pack at low temperatures is drawn from the waste heat discharged during operation and stored as latent heat in the second phase-change material. This recycles waste heat, reduces thermal management energy consumption, and increases the battery's energy density.

[0032] The above description is only an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and easier to understand, so that those skilled in the art can implement it according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are illustrated below. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are intended only to illustrate preferred embodiments and are not to be construed as limiting the present invention. It should be understood that the drawings described below are merely examples of the present invention, and that those skilled in the art will be able to derive other drawings from these drawings without inventive effort. Throughout the drawings, identical reference numerals are used to denote identical components.

[0034] In the attached figure:

[0035] Figure 1 It is a side structural diagram of the present invention;

[0036] Figure 2 It is a top view of the structure of the present invention;

[0037] Figure 3 、 Figure 4 This is an energy-saving effect diagram of another embodiment of the present invention.

[0038] The present invention will be further explained below with reference to the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0039] Specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0040] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the invention. The scope of protection of the present invention shall be as defined in the attached claims.

[0041] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings. However, the accompanying drawings do not limit the embodiments of the present invention.

[0042] For better understanding, Figures 1 to 4 As shown, a lithium battery thermal management system includes:

[0043] The inner layer phase change material heat buffer module 3 includes:

[0044] The first shell 8,

[0045] A battery pack 4 is placed in a first housing 8 and is filled with a first phase change material 6 ;

[0046] The thermoelectric device 2, one side of which is thermally connected to the first housing 8;

[0047] At least one outer layer phase change material thermal storage module 1, comprising:

[0048] The second shell 7 is thermally connected to the other side of the thermoelectric device 2 and is filled with a second phase change material 5.

[0049] The top cover 12 is provided on the second shell 7.

[0050] The electric-controlled trigger device 9 comprises:

[0051] Anode 10, which is connected to the positive pole of the power supply,

[0052] The cathode 11 is connected to the negative pole of the power supply. The anode 10 and the cathode 11 are inserted into the second shell 7 through the top cover 12 .

[0053] In a preferred embodiment of the lithium battery thermal management system, when the battery pack 4 is operating, heat is dissipated when the temperature of the battery pack 4 rises, and the first phase change material 6 absorbs heat, reducing the temperature rise of the battery pack 4. When the temperature continues to rise, the heat is conducted to the first shell 8 through the first phase change material 6, and then released to the second shell 7 by the thermoelectric device 2. The heat is conducted to the second phase change material 5 through the second shell 7, and the second phase change material 5 melts, converting the heat into latent heat for storage. When the battery pack 4 is shut down after operation, the heat continues to be stored in the second phase change material 5 in the form of latent heat. When the temperature of the battery pack 4 is lower than the low temperature threshold temperature, direct current is applied to the second phase change material 5 through the electronically controlled trigger device 9 to release the stored latent heat. The heat is conducted to the second shell 7 through the second phase change material 5, and the thermoelectric device 2 absorbs heat from the second shell 7 and releases heat to the first shell 8. The heat is sequentially conducted to the first phase change material 6 and the battery pack 4 through the first shell 8, thereby increasing the temperature of the battery pack 4.

[0054] In a preferred embodiment of the lithium battery thermal management system, the second phase change material 5 comprises a hydrated salt, the phase change temperature range of which is 30-40°C, the supercooling degree is not less than 20°C, and the supercooling state can be destroyed by direct current.

[0055] In a preferred embodiment of the lithium battery thermal management system, the first phase change material 6 includes paraffin wax, and its phase change temperature range is 30-50°C.

[0056] In a preferred embodiment of the lithium battery thermal management system, the positive electrode material of the battery pack 4 includes lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide and ternary materials, the negative electrode of the battery is a carbon material, and the battery pack 4 is connected in series, parallel, and grouped series and parallel.

[0057] In a preferred embodiment of the lithium battery thermal management system, the distance between the cathode 11 and the anode 10 does not exceed 3 cm.

[0058] In a preferred embodiment of the lithium battery thermal management system, the anode 10 is a silver rod with a diameter of not less than 2.5 mm, which is polished with 80, 200, 400, 600, and 800 grit sandpaper in sequence and coated with seed powder of the second phase change material 5, and the cathode 11 is graphite or silver.

[0059] In a preferred embodiment of the lithium battery thermal management system, the first phase change material 6 is doped with a high thermal conductivity material to form a composite phase change material.

[0060] In a preferred embodiment of the lithium battery thermal management system, the first shell 8 and the second shell 7 are made of aluminum.

[0061] The thermal management methods of lithium battery thermal management systems include:

[0062] Arrange a lithium battery thermal management system: the battery pack 4 is placed in a first shell 8 and the battery pack 4 is filled with a first phase change material 6; one side of the thermoelectric device 2 is thermally connected to the first shell 8; multiple outer phase change material thermal storage modules 1 surround the first shell 8, and a second shell 7 is thermally connected to the other side of the thermoelectric device 2. The second shell 7 is filled with a second phase change material 5, and the anode 10 and cathode 11 are inserted into the second shell 7 through the top cover 12;

[0063] When the battery pack 4 is in operation and the temperature of the battery pack 4 rises, heat is dissipated, and the first phase change material 6 absorbs the heat, reducing the temperature rise of the battery pack 4. When the temperature continues to rise, the heat is transferred to the first housing 8 through the first phase change material 6, and then released to the second housing 7 by the thermoelectric device 2. The heat is transferred to the second phase change material 5 through the second housing 7, and the second phase change material 5 melts, converting the heat into latent heat for storage.

[0064] When the battery pack 4 is shut down, heat continues to be stored in the second phase change material 5 in the form of latent heat. When the temperature of the battery pack 4 is lower than the low-temperature threshold temperature, direct current is applied to the second phase change material 5 through the electronically controlled trigger device 9 to release the stored latent heat. The heat is conducted to the second shell 7 through the second phase change material 5. The thermoelectric device 2 absorbs heat from the second shell 7 and releases heat to the first shell 8. The heat is conducted to the first phase change material 6 and the battery pack 4 in sequence through the first shell 8, thereby increasing the temperature of the battery pack 4.

[0065] In one embodiment, the system is a symmetrical structure.

[0066] In one embodiment, the system includes a temperature sensor for measuring the temperature of the inner layer phase change material thermal buffer module 3 and the outer layer phase change material heat storage module 1 and a processor connected to the temperature sensor. The processor is connected to the electronically controlled trigger device 9 to control the electronically controlled trigger device 9 based on the system including measuring the temperature of the inner layer phase change material thermal buffer module 3 and the outer layer phase change material heat storage module 1 to adjust the system temperature.

[0067] In one embodiment, the first phase change material 6 may be a paraffin-based phase change material with a phase change temperature range of 30°C to 50°C. The second phase change material 5 may be a hydrated salt of calcium chloride with a phase change temperature range of 30°C to 40°C and a supercooling degree of 25°C to 45°C. The second shell 7 and the first shell 8 may be aluminum shells. The connection between the thermoelectric device 2 and the shell may be coated with thermal conductive silicone grease. The first phase change material 6 may be doped with a high thermal conductivity material to form a composite phase change material. The anode 10 in the trigger device may be a silver electrode, and the cathode 11 may be a graphite electrode.

[0068] In one embodiment, this system achieves efficient thermal management of the lithium battery pack 4 through the synergistic effect of the thermoelectric device 2 and phase change material. When the temperature of the battery pack 4 rises, the inner first phase change material 6 absorbs waste heat released by the battery pack 4 and enters a solid-liquid two-phase state when the temperature exceeds a threshold. The thermoelectric device 2 absorbs heat from the inner first phase change material 6 and releases heat to the outer second phase change material 5, depending on the input current. The inner first phase change material 6 absorbs heat from the battery pack 4 and maintains a substantially constant temperature during the phase change, achieving rapid heat dissipation from the battery pack 4 and thus controlling the temperature rise of the battery pack 4. The outer second phase change material 5 absorbs heat from the thermoelectric device 2, melting from a solid state to a liquid state, storing the waste heat dissipated by the battery pack 4 as latent heat from the phase change. When the battery pack 4 is shut down, the second phase change material 5 is in a supercooled state, and the latent heat is not dissipated by changes in ambient temperature. When the battery pack 4 requires a cold start, the electronically controlled trigger device 9 applies direct current to the second phase-change material 5, altering the material's free energy in this state and providing nucleation centers for the liquid second phase-change material 5, causing it to undergo a phase change and release stored latent heat. The thermoelectric device 2 uses the heat released by the outer second phase-change material 5 as a heat source, heating the inner first phase-change material 6 according to the input current, thereby rapidly heating the battery pack 4. During battery operation, the system transfers waste heat to the outer second phase-change material 5 and stores it as latent heat for reuse during low-temperature cold starts. This increases the energy density of the battery pack 4, effectively improving its performance and efficiency over a wide temperature range.

[0069] In one embodiment, the system consists of an outer phase change material heat storage module 1, an inner phase change material heat buffer module 3, and a thermoelectric device 2. When the temperature of the battery pack 4 rises, the inner phase change material passively absorbs the heat of the battery pack 4, the cold end of the thermoelectric device 2 actively absorbs the heat of the inner phase change material, and the hot end heats the outer phase change material, storing the heat in the outer phase change material as latent heat. When the temperature of the battery pack 4 falls below the low-temperature threshold temperature, the electronically controlled trigger device 9 triggers the outer phase change material to release heat, the cold end of the thermoelectric device 2 absorbs the phase change latent heat of the outer phase change material, and the hot end heats the inner phase change material, thereby increasing the temperature of the battery pack 4. The present invention utilizes phase change materials and thermoelectric devices 2 to perform a combination of active and passive thermal management of lithium batteries, broadening the temperature range of lithium battery thermal management, realizing the recovery, storage, and utilization of waste heat from the battery pack 4, reducing the energy consumption of the battery during low-temperature cold starts, and improving the reliability of temperature rise control of the battery pack 4.

[0070] In one embodiment, a lithium battery thermal management system includes an outer phase change material heat storage module 1, an inner phase change material heat buffer module 3, and a thermoelectric device 2; the inner phase change material heat buffer module is composed of a battery pack 4, a first shell 8, and a first phase change material 6, the battery pack 4 is placed in the center of the first shell 8, and the battery pack 4 is filled with the first phase change material 6; one side of the thermoelectric device 2 is tightly connected to the first shell 8 in the inner phase change material heat buffer module, and the other side is tightly connected to the second shell 7 in the outer phase change material heat storage module 1; the thermoelectric effect of the thermoelectric device 2 is used to realize active heat conduction between the second shell 7 and the first shell 8, and absorb heat from the first shell 8 at high temperatures. It releases heat to the second shell 7, and absorbs heat from the second shell 7 and releases heat to the first shell 8 at low temperatures; the outer phase change material heat storage module 1 is composed of four sub-modules with the same structure and symmetrical position, each sub-module is composed of a second shell 7, an electric-controlled trigger device 9 and a second phase change material 5. The second shell 7 is filled with the second phase change material 5, and the electric-controlled trigger device 9 is connected to the top of the second shell 7. The anode 10 in the electric-controlled trigger device 9 is connected to the positive pole of the power supply, and the cathode 11 is connected to the negative pole of the power supply. The distance between the anode 10 and the cathode 11 does not exceed 3 cm. If the distance is too large, the internal resistance of the phase change material will be larger and the current density will be smaller, which may make the phase change triggering at low temperatures unsuccessful. The top cover 12 is connected to the top of the second shell 7, and the anode 10 and the cathode 11 are inserted into the second shell 7 through the top cover 12; the second shell 7 of the outer phase change material heat storage module 1 is filled with the second phase change material 5; when the battery pack 4 is working, the temperature rises, and the first phase change material 6 is used to dissipate heat when the temperature of the battery pack 4 rises, absorbing heat and reducing the temperature rise of the battery pack 4; when the temperature continues to rise, the heat is conducted to the first shell 8 through the first phase change material 6, and then the thermoelectric device 2 continues to absorb heat from the first shell 8 and releases heat to the second shell 7 of the outer phase change material heat storage module 1, and the heat is conducted to the second phase change material 5 through the second shell 7. The material 5 melts and converts the heat into latent heat for storage; when the battery pack 4 finishes working and is in a shutdown state, the second phase change material 5 is in a supercooled state and does not undergo phase change as the temperature drops, and the heat continues to be stored in the second phase change material 5 in the form of latent heat; when the temperature of the battery pack 4 is lower than the low temperature threshold temperature, direct current is applied to the second phase change material 5 through the electronically controlled trigger device 9 to induce the second phase change material 5 to solidify and release the stored latent heat. The heat is conducted to the second shell 7 through the second phase change material 5, and the thermoelectric device 2 absorbs heat from the second shell 7 and releases heat to the first shell 8 of the inner phase change material thermal buffer module 3. The heat is conducted to the first phase change material 6 and the battery pack 4 in turn through the first shell 8, thereby increasing the temperature of the battery pack 4.

[0071] In one embodiment, a thermoelectric device (TEC) consists of a ceramic substrate, copper electrodes, and a pn junction. Due to the Peltier effect, heat is absorbed from one side and released to the other. The amount of heat is related to the input current of the thermoelectric device. A TEC can be thought of as a refrigerator. The input energy causes the cold end to be below the ambient temperature and the hot end to be above the ambient temperature.

[0072] In one embodiment, the thermoelectric device is composed of an upper ceramic substrate, an upper copper guide plate, a PN junction, a lower copper guide plate, a lower ceramic substrate, and a side packaging layer. When current passes through the thermoelectric device, one side of the device absorbs heat and the other side releases heat. When the current direction is reversed, the heat-absorbing side and the heat-releasing side are also swapped.

[0073] In another embodiment, the present invention uses a battery module composed of 9 3000mAh lithium batteries to conduct thermal management experiment verification, and the verification cycle is "low temperature 600s heating + high temperature 1200s heat dissipation". The results are as follows Figure 3 、 Figure 4 As shown. This system reduces the energy consumption of the lithium battery thermal management system by 46%-58%, increases the energy density of the battery pack by 6%-27%, and reduces the consumption of external energy. This system separates the module used for heat storage from the module used for heat buffering and uses thermoelectric devices to regulate the heat in the two modules, avoiding the inherent contradiction between heat storage performance and thermal conductivity. It not only enhances the heat dissipation performance of the battery pack, but also enhances the heat storage capacity of the system, so that high-temperature heat dissipation and low-temperature cold start functions can be efficiently implemented in the same system. Specifically, a detailed description of this specific example, including its parameters, is shown below:

[0074] The first phase change material is expanded graphite doped with paraffin with a mass fraction of 6%, and its phase change temperature is 35°C. The shell containing the first phase change material is a hollow cubic shell with a length and width of 68mm, a height of 66mm, and a thickness of 2mm. The second phase change material is calcium chloride hydrate with a mass fraction of 48% calcium chloride, and its phase change temperature is 30°C. The supercooling degree is 30°C. The shell containing the second phase change material is a hollow cubic shell with a length and width of 68mm, a height of 30mm, and a thickness of 2mm. The thermoelectric device as a whole is 40mm long and wide, and 3.5mm high. m cubic package, its upper and lower ceramic substrates are both cubes with a side length of 40mm and a thickness of 0.7mm; the PN junction material is bismuth telluride, pi-shaped, 1.3mm high, and there are 127 pairs in total; the copper electrodes are rectangular sheets 0.4mm thick, covering the upper and lower PN junctions; the internal resistance of the thermoelectric device is 2 ohms, and the input current is 2A; the anode of the electronically controlled trigger device is a silver rod with a diameter of 2.5mm and a height of 50mm, and the cathode is a graphite rod of the same size. The DC voltage applied during triggering is 1.1V; the lithium battery discharge rate is 3C.

[0075] The selection or optimization principles for the above key parameters are as follows: First, the phase change temperature of the phase change material should be 5°C or approximately 5°C higher than the optimal operating temperature of the lithium battery. Second, the phase change material should have the highest possible latent heat value while ensuring a supercooling temperature of no less than 20°C. The thermoelectric device should have the lowest possible internal resistance, and the input current should increase with the size and discharge rate of the lithium battery pack to ensure heat dissipation performance. It is understood that the settings of other parameters or morphologies are based on ensuring the above technical effects.

[0076] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0077] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A lithium battery thermal management system, characterized in that: These include, The inner layer phase change material thermal buffer module comprises: first shell, A battery pack is placed in the first housing and is filled with a first phase change material; a thermoelectric device, one side of which is thermally connected to the first housing; At least one outer phase change material thermal storage module comprising: The second shell is thermally connected to the other side of the thermoelectric device, and the second shell is filled with a second phase change material. a top cover, which is provided on the second shell, An electrically controlled triggering device comprising: Anode, which is connected to the positive pole of the power supply, The cathode is connected to the negative pole of the power supply, and the anode and cathode are inserted into the second shell through the top cover.

2. The lithium battery thermal management system according to claim 1, wherein: Preferably, when the battery pack is working, heat is dissipated when the temperature of the battery pack rises, and the first phase change material absorbs heat to reduce the temperature rise of the battery pack; when the temperature continues to rise, the heat is conducted to the first shell through the first phase change material, and then released to the second shell by the thermoelectric device, and the heat is conducted to the second phase change material through the second shell, the second phase change material melts, and the heat is converted into latent heat for storage; when the battery pack finishes working and is in a shutdown state, the heat continues to be stored in the second phase change material in the form of latent heat; when the temperature of the battery pack is lower than the low temperature threshold temperature, direct current is applied to the second phase change material through the electronically controlled trigger device to release the stored latent heat, and the heat is conducted to the second shell through the second phase change material, the thermoelectric device absorbs heat from the second shell and releases heat to the first shell, and the heat is conducted to the first phase change material and the battery pack in sequence through the first shell, thereby increasing the temperature of the battery pack.

3. The lithium battery thermal management system according to claim 1, wherein: The second phase change material includes hydrated salt, the phase change temperature range of which is 30-40°C, the supercooling degree is not less than 20°C, and the supercooling state can be destroyed by direct current.

4. The lithium battery thermal management system according to claim 1, wherein: The first phase change material includes paraffin, and its phase change temperature range is 30-50°C.

5. The lithium battery thermal management system according to claim 1, wherein: The battery positive electrode materials of the battery pack include lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide and ternary materials, the battery negative electrode is a carbon material, and the battery pack connection mode is series connection, parallel connection, and group series and parallel connection.

6. The lithium battery thermal management system according to claim 1, wherein: The distance between the cathode and the anode should not exceed 3 cm.

7. The lithium battery thermal management system according to claim 1, wherein: The anode is a silver rod with a diameter of not less than 2.5 mm, which is polished with 80, 200, 400, 600, and 800 grit sandpaper in sequence and coated with seed powder of the second phase change material. The cathode is graphite or silver.

8. The lithium battery thermal management system according to claim 1, wherein: The first phase change material is doped with a high thermal conductivity material to form a composite phase change material.

9. The lithium battery thermal management system according to claim 1, wherein: The first housing and the second housing are made of aluminum.

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