Lithium ion battery multi-temperature-zone thermal management system and method based on photo-thermal phase change material

Abstract

The invention provides a lithium ion battery multi-temperature-zone thermal management system based on a photo-thermal phase change material. The lithium ion battery multi-temperature-zone thermal management system comprises a lithium ion battery monomer, a first phase change material pool, a second phase change material pool, a heat pipe and a thermoelectric module. When the lithium ion battery works, the thermal management system carries out heat dissipation on the battery through the phase change process of the photo-thermal phase change material. During high-temperature or long-time high-power charging and discharging, in order to effectively control the temperature rise of the battery, the thermoelectric module starts a refrigeration mode, and the heat of the battery is taken out through the heat pipe and is finally absorbed by the second phase change material. When the lithium ion battery needs to be preheated or insulated, the heat management system projects light to the photo-thermal phase change material through the light guide assembly, so that the photo-thermal phase change material absorbs light, generates heat and transmits the heat to the battery, the thermoelectric module starts a heating mode if necessary, and the heat generated by the thermoelectric module is reversely transmitted to the battery through the heat pipe. Therefore, the battery is assisted in temperature rise or prevented from excessively fast temperature loss. The invention further provides a corresponding thermal management method based on the thermal management system.

Description

Technical Field

[0001] The present invention relates to the technical field of battery thermal management, and particularly relates to a multi-temperature zone thermal management system and method for lithium-ion batteries based on photothermal phase change materials. Background Art

[0002] Currently, in the electric vehicle market, lithium-ion batteries are widely selected as the main power source for electric vehicles due to their high energy density, high power density, and long service life. However, the performance and lifespan of lithium-ion batteries are strictly limited by their operating temperature and the temperature difference between cells. Generally, the operating temperature for the safe operation of lithium-ion batteries is set between 20°C and 40°C, and the maximum temperature difference between cells does not exceed 5°C. Once the temperature exceeds the safe range, the performance of lithium-ion batteries will rapidly decay. In particular, high-temperature environments can cause irreversible damage to operating lithium-ion battery packs, and there is even a risk of combustion and explosion. When the temperature is too low, the capacity and power density of lithium-ion batteries will drop sharply. Moreover, the charging process at low temperatures will cause non-uniform precipitation of lithium metal on the surface of the negative electrode, thus forming dendrites and piercing the separator. This will not only lead to the loss of lithium activity and the attenuation of the battery capacity, but the damage to the internal structure will also induce a short circuit inside the battery.

[0003] In view of this, the use of lithium-ion batteries must be paired with a corresponding thermal management system. Currently, lithium-ion battery thermal management systems can be divided into three categories according to the working media they use: air, liquid, and phase change materials. Among them, the thermal management system using air mainly drives cold air or hot air to flow over the battery surface to absorb or give heat to the battery. This thermal management method is environmentally friendly and economical. However, due to the thermophysical properties of air, its heat transfer efficiency is low. The thermal management system using liquid replaces air with a liquid having a relatively high thermal conductivity and specific heat. However, when using this system to heat the battery in cold weather, the liquid working medium will consume more energy. In addition, such a thermal management system is heavy, has a high maintenance cost, and there is a hidden danger of liquid leakage. As for the thermal management system using phase change materials, it mainly relies on the melting or solidification of phase change materials to absorb or give heat to the battery. Generally, phase change materials have a large latent heat and small temperature fluctuations during the phase change process. Therefore, the thermal management system using phase change materials can provide relatively efficient and relatively uniform temperature control thermal management services for lithium-ion batteries. However, it should be noted that when the phase change materials stored in the thermal management system are completely melted, the related phase change cooling function will completely disappear. Moreover, the thermal response efficiency of phase change materials is low. Therefore, the thermal management solution using phase change materials is currently not suitable for high-load or fast-changing temperature working scenarios.

[0004] It should be specifically pointed out here that for battery heating in low-temperature environments, in addition to the aforementioned air and liquid heating solutions, there are also electric heating methods based on heating sheets, heating films, and thermoelectric modules (or Peltier effect elements). Heating sheets are usually placed on the sides or bottoms of battery packs, but the heating process takes a long time and is extremely likely to cause uneven temperature distribution among cells. As for heating films, due to their flexible shape and small thickness, they are often directly attached to the battery surface. The heating process of heating films has a relatively high heat transfer efficiency and a small temperature gradient. However, heating films are expensive and have high maintenance costs. What's more troublesome is that they are easily damaged in humid environments. As for thermoelectric modules, when an electric current passes through the connection between two different semiconductors contained therein, it can release heat on one side and absorb heat on the other side. Therefore, the thermoelectric module can switch the heating or cooling function of the designated working surface by changing the direction of the input current. Generally speaking, the above three electric heating methods all consume electrical energy. If the relevant energy consumption depends on the low-temperature discharge of lithium-ion batteries, it can be predicted that the use of these electric heating methods will directly cause low-temperature damage to the batteries and also reduce the capacity of the lithium-ion batteries themselves, thus affecting the mileage of electric vehicles.

[0005] In summary, for lithium-ion batteries, it is very necessary to develop a thermal management system and management method that can meet their cooling and heating requirements in different temperature ranges, ensuring that lithium-ion batteries can be effectively cooled under medium- and high-temperature working conditions, and obtaining necessary heating and heat preservation protection during low-temperature startup or operation. Summary of the Invention

[0006] Aiming at the defects in the prior art, the present invention provides a multi-temperature zone thermal management system and method for lithium-ion batteries based on photothermal phase change materials. By utilizing the phase change heat transfer and light absorption heat generation functions of photothermal phase change materials, low-temperature heating protection and medium- and high-temperature cooling and heat dissipation are implemented for lithium-ion batteries. In addition, by further coupling heat pipes and thermoelectric modules, the relevant heating protection is made more flexible and controllable, and at the same time, the technical problem of rapid deterioration of battery cooling after the phase change material is completely melted is solved.

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions: The first aspect of the present invention is to provide a multi-temperature zone thermal management system for lithium-ion batteries based on photothermal phase change materials, including: Lithium-ion battery cells, with first phase change material pools respectively arranged on both sides; The first phase change material pool, which is filled with a first phase change material and connected to an external light guide component; wherein, the first phase change material is a photothermal phase change material; A heat pipe, sandwiched between the lithium-ion battery cell and the first phase change material pool, and one end of it extends outside the lithium-ion battery cell and the first phase change material pool and fits with the first working surface of the thermoelectric module; A thermoelectric module, including a first working surface and a second working surface which are oppositely arranged; A second phase change material pool, which is attached to the second working surface of the thermoelectric module and filled with a second phase change material inside.

[0008] Optionally, the light guide assembly includes: A light guiding component, with both ends respectively connected to a light extracting component and a scattering component for transmitting light beams; A light extracting component, connected to one end of the light guiding component for collecting natural light or artificial light; A scattering component, arranged inside the first phase change material pool, for receiving the light beam transmitted by the light guiding component and projecting it in multiple directions to the surrounding photo-thermal phase change material.

[0009] Optionally, the scattering component includes: A light bead, made of a light-transmitting material and provided with a cavity communicated with the light guiding component inside; A scatterer, placed inside the cavity of the light bead for scattering the light beam transmitted by the light guiding component in multiple directions.

[0010] Optionally, the light guiding component includes an optical fiber or a light guide column.

[0011] Optionally, the melting point of the photo-thermal phase change material is lower than that of the second phase change material.

[0012] Optionally, the thermal management system further includes: Heat dissipation fins, including a fin group and a bottom plate, the fin group is arranged inside the second phase change material pool and immersed in the second phase change material, and the bottom plate is arranged outside the second phase change material pool and attached to the second working surface of the thermoelectric module.

[0013] Optionally, a groove for embedding the heat pipe is provided on one side of the first phase change material pool facing the lithium-ion battery cell.

[0014] Optionally, the thermal management system further includes: A box body, at least used for accommodating the lithium-ion battery cell, the first phase change material pool and the second phase change material pool, and the lithium-ion battery cell is located above the second phase change material pool; A bracket, with the bottom end abutted against the bottom of the box body and the top end extending between the lithium-ion battery cell and the second phase change material pool, at least used for supporting the first phase change material pool.

[0015] The second aspect of the present invention is to provide a management method for a lithium-ion battery multi-temperature zone thermal management system based on the photo-thermal phase change material as described above, including the following steps: Detect at least the real-time temperature on the surface of one lithium-ion battery cell, and make the following judgments based on the real-time temperature: When the real-time temperature is lower than the preset temperature range, the external light guide component is controlled to be enabled to irradiate the photothermal phase change material, and the characteristic of the photothermal phase change material absorbing light and generating heat is utilized to heat the single lithium-ion battery; and when the user requests rapid temperature increase, the thermoelectric module is controlled to be enabled in the heating mode, and the additional heat generated by the thermoelectric module is transferred to the heat pipe through the first working surface of the thermoelectric module, and then transferred to the single lithium-ion battery; When the real-time temperature is maintained within the preset temperature range, the external light guide component is controlled to switch to the idle state to passively control the temperature of the single lithium-ion battery by utilizing the phase change process of the photothermal phase change material itself; meanwhile, the thermoelectric module is controlled to switch to the idle state; When the real-time temperature is higher than the preset temperature range, the external light guide component is controlled to switch to the idle state; meanwhile, the thermoelectric module is controlled to be enabled in the cooling mode, and the battery heat is transferred to the first working surface of the thermoelectric module through the heat pipe in contact with the single lithium-ion battery, thereby implementing cooling.

[0016] As can be seen from the above technical solutions, the beneficial effects of the present invention are: 1) The present invention introduces a photothermal phase change material to implement battery thermal management. On the one hand, the solid-liquid phase change heat of the phase change material is fully utilized to efficiently cool the lithium-ion battery. On the other hand, the light beam is projected onto the photothermal phase change material through the light guide component, enabling it to absorb light and generate heat and transfer the heat to the adjacent single battery through the outer shell of the first phase change material pool, thereby providing the preheating required for the lithium-ion battery at low temperatures during startup and also effectively insulating and protecting it during operation. Compared with the traditional electric heating method based on heating sheets or heating films, the heating scheme of the present invention can directly utilize sunlight without additional power supply or consumption of the power of the lithium-ion battery itself. Therefore, the present invention provides a more environmentally friendly and energy-saving lithium-ion battery thermal management scheme and management method. It is particularly suitable for the use, operation, and maintenance of lithium-ion batteries in high-altitude areas with strong sunlight and low temperatures.

[0017] 2) The coupled use of the photothermal phase change material, the heat pipe, and the thermoelectric module also provides a more flexible and controllable thermal management scheme for users. When the battery is in a low-temperature environment, in addition to the photothermal phase change material absorbing light and generating heat, the thermoelectric module can be enabled in the heating mode based on the actual needs of the user. The additional heat generated by it can be directly transferred to the lithium-ion battery through the heat pipe, thereby effectively shortening the battery temperature increase time. On the other hand, when the lithium-ion battery operates in a high-temperature environment, if the photothermal phase change material has completely melted at this time and cannot continue to efficiently cool the battery through phase change, the thermoelectric module can automatically be enabled in the cooling mode, thereby quickly cooling the battery heat derived from the heat pipe at the first working surface of the thermoelectric module and avoiding the rapid accumulation of heat on the battery surface and the soaring of the battery temperature.

[0018] 3) The thermal management system of the present invention has no moving parts, and its core functions of cooling and heating are implemented by relying on the passive phase change heat transfer and photothermal conversion characteristics of the photothermal phase change material. The thermoelectric module for auxiliary cooling and heating can quickly perform mode conversion and power matching through electrical control. The entire system has a compact and lightweight structure, a fast system response, high operating reliability and stability, and can fully meet the cooling, heat preservation and heating requirements of lithium-ion batteries in different temperature ranges, especially suitable for lithium-ion batteries on mobile devices. Description of the Drawings

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0020] Figure 1 Schematic three-dimensional structure diagram of the present thermal management system; Figure 2 Schematic diagram of the distribution of heat pipes on both sides of a single lithium-ion battery; Figure 3 Cross-sectional view of the present thermal management system; Figure 4 Schematic diagram of the groove structure of the outer shell of the first phase change material pool; Reference numerals: 1 - First phase change material pool, 2 - Second phase change material pool, 3 - Single lithium-ion battery, 4 - Optical guide assembly, 5 - Heat pipe, 6 - Thermoelectric module, 7 - Heat dissipation fins, 8 - Bracket; 11 - Groove, 41 - Light guiding component, 42 - Scattering component. Specific Embodiments

[0021] The following will describe in detail the embodiments of the technical solutions of the present invention with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, so they are only examples and cannot be used to limit the protection scope of the present invention.

[0022] Please refer to Figures 1-4, the lithium-ion battery multi-temperature zone thermal management system based on the photothermal phase change material provided by the present invention includes a lithium-ion battery monomer 3, a first phase change material pool 1, a second phase change material pool 2, a heat pipe 5 and a thermoelectric module 6. The first phase change material pools 1 are respectively arranged on both sides of the lithium-ion battery monomer 3, and the first phase change material is filled in the first phase change material pools 1. In the present invention, the first phase change material is selected as the photothermal phase change material. Since the photothermal phase change material is filled in the first phase change material pools 1, the first phase change material pools 1 are connected to the external light guide assembly 4, so that in the low-temperature working condition, the light beam is projected to the photothermal phase change material in the pool through the light guide assembly 4, so that it absorbs light and generates heat and transfers the heat to the adjacent lithium-ion battery monomer 3 through the outer shell of the first phase change material pool 1. This not only provides the preheating required for the battery to start at low temperature, but also implements effective heat preservation protection for its operation, reducing or avoiding the negative impact of the low-temperature environment on the working performance and life of the battery. For example, when the weather is sunny and the sunlight is abundant, the sunlight can be directly projected to the photothermal phase change material through the light guide assembly 4, so that it quickly absorbs light and generates heat, and a part of the generated heat will be directly transferred to the adjacent lithium-ion battery monomer 3 through the outer shell of the first phase change material pool 1. In rainy weather or when the sunlight is insufficient, an artificial light source such as a xenon light source can be used to replace the sunlight and irradiate the photothermal phase change material, so that the lithium-ion battery monomer 3 can still obtain heat. On the other hand, in the medium-temperature working condition, the heat generated when the lithium-ion battery monomer 3 works will be transferred to the photothermal phase change material through the outer shell of the first phase change material pool 1, and the photothermal phase change material will absorb the heat and heat up. When the temperature of the photothermal phase change material reaches its melting point, the photothermal phase change material will melt, and then store the heat generated by the battery in the form of latent heat, thereby playing a role in cooling and dissipating heat for the working lithium-ion battery monomer 3.

[0023] In particular, a plurality of heat pipes 5 are distributed between the lithium-ion battery cell 3 and the first phase change material pool 1, and one end of each heat pipe 5 extends outside the lithium-ion battery cell 3 and the first phase change material pool 1 and is attached to the first working surface of the thermoelectric module 6. Specifically, the thermoelectric module 6 includes a first working surface and a second working surface arranged opposite to each other. The second working surface is attached to the second phase change material pool 2, and the second phase change material pool 2 is arranged close to the lithium-ion battery cell 3, preferably below the lithium-ion battery cell 3, and of course, it can also be arranged around the lithium-ion battery cell 3. Among them, the second phase change material pool 2 is filled with a second phase change material. Generally, a non-photo-thermal phase change material is selected as the second phase change material. In the present invention, the combined use of the photo-thermal phase change material, the heat pipe 5, and the thermoelectric module 6 provides a more flexible and controllable thermal management solution for lithium-ion batteries. It can be predicted that when the lithium-ion battery cell 3 is in a low-temperature environment, in addition to the photo-thermal phase change material absorbing light and generating heat, the thermoelectric module 6 can automatically or based on user needs quickly enable the heating mode and provide additional heat to the lithium-ion battery cell 3 through the heat pipe 5. This can effectively shorten the battery warming-up time, thus meeting the user's demand for quickly using the vehicle in a low-temperature environment. It should be noted that the power source of the thermoelectric module 6 comes from a backup power source such as a lead-acid battery, rather than the lithium-ion battery itself. On the other hand, when the lithium-ion battery cell 3 operates in medium and high-temperature environments, the photo-thermal phase change material gradually or completely loses its cooling function due to partial or complete melting. At this time, the thermoelectric module 6 can automatically enable the refrigeration mode, quickly transfer the heat of the lithium-ion battery cell 3 derived from the heat pipe 5 to the first working surface of the thermoelectric module 6, and then implement refrigeration, thereby effectively avoiding the rapid accumulation of heat on the surface of the lithium-ion battery cell 3 and the soaring of temperature at high temperatures.

[0024] Based on the above thermal management system, the present invention also provides a management method for the thermal management system, which specifically includes the following steps: Detect at least the real-time temperature on the surface of one lithium-ion battery cell 3, and make the following judgments based on the real-time temperature: When the real-time temperature is lower than the preset temperature range, control the external light guide assembly 4 to be enabled to illuminate the photo-thermal phase change material, and utilize the characteristic of the photo-thermal phase change material absorbing light and generating heat to heat the lithium-ion battery cell 3; and when the user requests rapid warming, control the thermoelectric module 6 to enable the heating mode, and transfer the additional heat generated by the thermoelectric module 6 to the heat pipe 5 through the first working surface of the thermoelectric module 6, and then transfer it to the lithium-ion battery cell 3; When the real-time temperature is maintained within the preset temperature range, control the external light guide assembly 4 to switch to the idle state to passively control the temperature of the lithium-ion battery cell 3 by using the phase change process of the photo-thermal phase change material itself; at the same time, control the thermoelectric module 6 to switch to the idle state; When the real-time temperature is higher than the preset temperature range, the external optical waveguide component 4 is controlled to switch to the idle state; at the same time, the thermoelectric module 6 is controlled to enable the refrigeration mode, and the heat of the battery is transferred to the first working surface of the thermoelectric module 6 through the heat pipe 5 in contact with the lithium-ion battery cell 3, thereby implementing refrigeration.

[0025] Specifically: When the working temperature of the battery rises, the first phase change material absorbs the heat generated by the battery, and this endothermic process will cause the temperature of the first phase change material to rise. When the temperature of the first phase change material reaches its melting point, the material will undergo a solid-liquid phase change, thereby converting the absorbed heat into its latent heat and storing it. When the battery continuously discharges at a large current for a long time or the ambient temperature exceeds the melting point of the first phase change material, the first phase change material will continuously absorb heat from the battery and the surrounding environment until it completely melts. At this time, the first phase change material in the thermal management system no longer has the ability of phase change cooling and cannot implement efficient heat dissipation for the lithium-ion battery. To overcome the above difficulties, the thermoelectric module 6 of the present invention turns on the refrigeration mode, and the heat of the battery is exported through the heat pipe 5 and brought to its first working surface, thereby implementing refrigeration. It should be noted that the refrigeration mode of the thermoelectric module 6 requires its second working surface to continuously release heat to the second phase change material in the second phase change material pool 2 through the heat dissipation fins 7. At this time, the second phase change material will absorb heat and increase in temperature. When the temperature of the second phase change material reaches its melting point, the second phase change material will undergo a phase change and finally store the waste heat of the above system in the form of latent heat, thereby implementing cooling and temperature control for the lithium-ion battery under this working condition. It is worth mentioning that the thermoelectric module 6 is electrically controlled and therefore has a relatively fast response speed. The present invention can be equipped with a thermoelectric module 6 for each lithium-ion battery cell 3 alone, and by dynamically adjusting the current direction and magnitude of the thermoelectric module 6, agile and precise battery thermal management can be implemented.

[0026] When the ambient temperature drops and is lower than the freezing point of the first phase change material, all the phase change materials in the thermal management system will solidify, and their solidification process will release the waste heat absorbed during battery operation. Specifically, since the first phase change material pool 1 is arranged on both sides of the lithium-ion battery cell 3, part of the heat released during the solidification process of the first phase change material will directly return to the surface of the lithium-ion battery cell 3, preventing the latter from losing temperature too quickly at low temperatures. In addition, due to the low thermal conductivity of the solid phase change material, the solidified first phase change material can also provide good heat preservation for the lithium-ion battery cell 3. When the ambient temperature further drops below the preset temperature range, the present invention will implement heating protection. First, the light beam of sunlight or artificial light source is introduced into the first phase change material to make it absorb light and generate heat, and the generated heat will be transferred to the adjacent lithium-ion battery cell 3 through the outer shell of the first phase change material pool 1 to implement heating of the battery and prevent or reduce the harm of the low-temperature environment to the startup or operation of the lithium-ion battery. If the user further requests faster battery heating or the sunlight or artificial light illumination is insufficient, the thermoelectric module 6 of the present invention will turn on the heating mode. The additional heat generated by the thermoelectric module 6 will be transferred back to the lithium-ion battery cell 3 through the heat pipe 5, so as to ensure that its temperature can rise to the appropriate temperature required for battery operation faster and meet the subsequent startup needs of the user. Embodiment

[0027] This embodiment aims to provide a specific thermal management solution for different temperature ranges. It can be known from a large number of literature data that the normal operating temperature range of current lithium-ion batteries is 20°C - 40°C. Therefore, in this embodiment, a photothermal phase change material with a melting point of 30°C is selected as the first phase change material, and a conventional phase change material with a melting point of 45°C is selected as the second phase change material, that is, the melting point of the photothermal phase change material is lower than that of the second phase change material. The specific control strategy is as follows: Below the first temperature range of 5°C: The light guide component 4 is enabled, and the photothermal phase change material absorbs light and generates heat; and the thermoelectric module decides whether to turn on the heating mode based on user needs; specifically, the user needs can be proposed in real time (including but not limited to manual operation, voice commands, etc.), or can be preset (such as automatically executed when the temperature is lower than 0°C); In the second temperature range of 5°C - 20°C: Most existing lithium-ion batteries can work normally in this temperature range. At this time, both the first phase change material and the second phase change material are in a solid state and their corresponding thermal conductivities are relatively low. Since the first phase change material pool 1 is distributed around the lithium-ion battery cell 3, the heat generated during its operation is not easily dissipated to the surrounding environment through the thermal conductivity of the solid first phase change material, and can just maintain the temperature of the lithium-ion battery cell 3 as much as possible. For this working condition, no thermal management measures can be provided, or it can be decided whether to turn on the heating mode of the light guide component 4 or the thermoelectric module 6 according to user needs; The third temperature range of 20°C - 40°C: The lithium-ion battery cell 3 has the most comfortable thermal state in this temperature range. At this time, passive temperature control and cooling of the lithium-ion battery cell 3 are mainly implemented by the phase change heat absorption of the first phase change material. Therefore, when the temperature of the lithium-ion battery cell 3 is in this temperature range, the light guide assembly 4 and the thermoelectric module 6 are in an idle state.

[0028] The fourth temperature range above 40°C or high-power long-time charge and discharge conditions: The first phase change material in the thermal management system has completely melted and lost the ability of phase change cooling. In this temperature range, the thermoelectric module 6 automatically turns on the refrigeration mode and implements refrigeration on the lithium-ion battery cell 3 through the heat pipe 5. A large amount of waste heat derived from the heat pipe 5 will ultimately be transferred to the second phase change material. After absorbing heat, the second phase change material will heat up. If its temperature rises to reach the melting point of the second phase change material, the second phase change material will then undergo a solid-liquid phase change. Embodiment

[0029] This embodiment aims to provide a specific structure of the light guide assembly 4 suitable for the multi-temperature range thermal management system of the lithium-ion battery of the present invention. Please refer to Figure 3, the optical guide component 4 includes a light guide member 41, a light extraction member (not shown in the figure), and a scattering member 42; both ends of the light guide member 41 are respectively connected to the light extraction member and the scattering member 42 for transmitting light beams. The light guide member 41 can be a light guide column or an optical fiber, etc.; the light extraction member is connected to one end of the light guide member 41 for collecting natural light or artificial light; the scattering member 42 is disposed in the first phase change material pool 1 for receiving the light beam transmitted by the light guide member 41 and projecting it in multiple directions to the surrounding photo-thermal phase change material, so that the photo-thermal phase change material undergoes a photo-thermal effect after being irradiated, that is, converts light energy into heat energy. Obviously, the first phase change material pool 1 can be connected to one or more light guide members 41, and the light guide member 41 buried in the first phase change material pool 1 can also adopt a multi-fork structure, and then a plurality of scattering members 42 are arranged orderly or randomly in different directions in the photo-thermal phase change material. The scattering members 42 arranged in multiple layers and in multiple directions provide illumination to the photo-thermal phase change material in the pool, so that the photo-thermal phase change material in the first phase change material pool 1 absorbs light and generates heat at multiple points simultaneously, and then can quickly increase its temperature. More preferably, in this embodiment, the scattering member 42 specifically includes a light bead and a scatterer; the light bead is made of a light-transmitting material, such as a spherical quartz glass structure, and a cavity communicating with the light guide member 41 is provided in the light bead; the scatterer is disposed in the cavity of the light bead for scattering the light beam transmitted by the light guide member 41 in multiple directions. In addition, if a light guide column, such as a quartz light guide column, is selected as the light guide member 41, diffuse reflection treatment can also be directly performed at the end of the quartz column to roughen the light-emitting surface of the quartz column, such as frosting, chemical etching, surface coating, or laser engraving a microlens array, etc., so as to increase the angle and uniformity of the light spot; or the light outlet of the quartz column can be processed into a light cap with different shapes to change the emission angle, such as processing the end of the quartz column into a light guide cone with side light transmission.

[0030] As a further improvement to the above solution, please refer to Figure 3 and Figure 4 , the thermal management system further includes a heat dissipation fin 7, the heat dissipation fin 7 includes a fin group and a bottom plate, the fin group is arranged on the side of the bottom plate facing away from the thermoelectric module 6, the fin group is disposed in the second phase change material pool 2 and immersed in the second phase change material, the bottom plate is disposed outside the second phase change material pool 2 and is attached to the second working surface of the thermoelectric module 6, and the heat discharged by the thermoelectric module 6 is received through the bottom plate, and then the heat is quickly transferred to the second phase change material by means of a plurality of fin groups. For the fixing method of the heat dissipation fin 7, the present invention adopts a plug-in installation, that is, first plug and fix the fin group to the second phase change material pool 2, and then fill and encapsulate the liquid second phase change material.

[0031] As a further improvement to the above solution, please refer to Figure 4, a groove 11 for embedding the corresponding heat pipe 5 is formed on one side of the first phase change material pool 1 facing the lithium-ion battery cell 3, so that the surface of the lithium-ion battery cell 3, the heat pipe 5, and the side surface of the first phase change material pool 1 can be better closely attached, reducing the contact thermal resistance and facilitating the transfer of relevant heat. In particular, please refer to Figure 1 and Figure 2 , one end of the heat pipe 5 extends below the lithium-ion battery cell 3 and is bent into a horizontal arrangement, and its surface is closely attached to the upper surface of the thermoelectric module 6, that is, the first working surface. Since a gap is formed between the horizontally arranged heat pipe 5 after bending and the upper lithium-ion battery cell 3, in order to prevent heat escape of the heat pipe 5 exposed in the gap in a low-temperature environment, a flexible heat-insulating material, such as heat-insulating cotton, bubble gum, etc., needs to be filled in the gap. Preferably, to further ensure the working efficiency of the heat pipe 5, all the heat pipes 5 located on both sides of the same lithium-ion battery cell 3 extend to the outside of the lithium-ion battery cell 3 and are embedded in the same fixing plate, and then are attached to the first working surface of the thermoelectric module 6 through the fixing plate, integrating and fixing multiple heat pipes 5. On the one hand, it is convenient for the docking and installation of the heat pipe 5 and the thermoelectric module 6, and on the other hand, it can effectively avoid the possible poor contact problem between the heat pipes 5 when they are individually attached to the thermoelectric module 6.

[0032] As a further improvement to the above solution, the thermal management system further includes a box body and a bracket 8. Please refer to Figure 1 , the box body is at least used to accommodate the lithium-ion battery cell 3, the first phase change material pool 1, and the second phase change material pool 2, and the lithium-ion battery cell 3 is located above the second phase change material pool 2; the bottom end of the bracket 8 abuts against the bottom of the box body, and the top end extends between the lithium-ion battery cell 3 and the second phase change material pool 2 to at least support the first phase change material pool 1. Obviously, the support of the lithium-ion battery cell 3 can also be borne by the bracket 8 together. The bracket 8 adopted in the present invention has a U-shaped cross section and can be prepared by a sheet metal process. The second phase change material pool 2 is directly placed inside the U-shaped bracket 8. The ends of the two arms of the U-shaped bracket 8 are both bent inward to form a supporting platform for placing the first phase change material pool 1 and the lithium-ion battery cell 3. A plugging component can be arranged on the supporting platform for positioning and installing the first phase change material pool 1 and the lithium-ion battery cell 3. Of course, the cross-sectional shape of the bracket 8 can also adopt other structures such as an I-shaped, Z-shaped, or C-shaped structure. At this time, two brackets 8 need to be correspondingly arranged for a single second phase change material pool 2, and the second phase change material pool 2 is clamped between the two brackets 8, and plugging components are respectively arranged at the top ends of the brackets 8. In addition, the support of the lithium-ion battery cell 3 and the first phase change material pool 1 can also adopt a support plate, which is arranged between the lithium-ion battery cell 3 and the second phase change material pool 2, and its two ends are respectively fixedly connected to the inner wall of the box body.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention.

Claims

1. A multi-temperature zone thermal management system for a lithium-ion battery based on a photothermal phase change material, characterized in that, Including: A lithium-ion battery cell (3) with a first phase change material pool (1) provided on each of its two sides; The first phase change material pool (1) filled with a first phase change material inside and connected to an external light guide assembly (4); wherein, the first phase change material is a photothermal phase change material; A heat pipe (5) sandwiched between the lithium-ion battery cell (3) and the first phase change material pool (1), and one end of which extends outside the lithium-ion battery cell (3) and the first phase change material pool (1) and fits against the first working surface of a thermoelectric module (6); The thermoelectric module (6) includes a first working surface and a second working surface arranged oppositely; A second phase change material pool (2) fits against the second working surface of the thermoelectric module (6), and is filled with a second phase change material inside.

2. The lithium-ion battery multi-temperature zone thermal management system based on a photothermal phase change material according to claim 1, wherein, The light guide assembly (4) includes: A light guiding component (41) with both ends respectively connected to a light collecting component and a scattering component (42) for transmitting light beams; The light collecting component is connected to one end of the light guiding component (41) for collecting natural light or artificial light; The scattering component (42) is arranged inside the first phase change material pool (1) for receiving the light beams transmitted by the light guiding component (41) and projecting them multi-directionally to the surrounding photothermal phase change materials.

3. The lithium-ion battery multi-temperature zone thermal management system based on a photothermal phase change material according to claim 2, wherein, The scattering component (42) includes: Light beads made of a light-transmitting material and provided with a cavity communicating with the light guiding component (41) inside; A scatterer arranged inside the cavity of the light beads for scattering the light beams transmitted by the light guiding component (41) multi-directionally.

4. The lithium-ion battery multi-temperature zone thermal management system based on a photothermal phase change material according to claim 2 or 3, characterized in that The light guiding component (41) includes an optical fiber or a light guide column.

5. The lithium-ion battery multi-temperature zone thermal management system based on a photothermal phase change material according to any one of claims 1-3, characterized in that, The melting point of the photothermal phase change material is lower than that of the second phase change material.

6. The lithium-ion battery multi-temperature zone thermal management system based on a photothermal phase change material according to claim 5, wherein Also including: A heat dissipation fin (7) including a fin group and a bottom plate, the fin group is arranged inside the second phase change material pool (2) and immersed in the second phase change material, and the bottom plate is arranged outside the second phase change material pool (2) and fits against the second working surface of the thermoelectric module (6).

7. The lithium-ion battery multi-temperature zone thermal management system based on a photothermal phase change material according to claim 5, characterized in that, A groove (11) for the heat pipe (5) to be embedded is provided on one side of the first phase change material pool (1) facing the lithium-ion battery cell (3).

8. The lithium-ion battery multi-temperature zone thermal management system based on a photothermal phase change material according to claim 5, wherein Also including: A box body at least for accommodating the lithium-ion battery cell (3), the first phase change material pool (1) and the second phase change material pool (2), and the lithium-ion battery cell (3) is located above the second phase change material pool (2); A bracket (8) with its bottom end abutted against the bottom of the box body and its top end extending between the lithium-ion battery cell (3) and the second phase change material pool (2) for at least supporting the first phase change material pool (1).

9. A management method for a multi-temperature zone thermal management system of a lithium-ion battery based on a photothermal phase change material according to any one of claims 1-8, characterized in that, Including the following steps: At least detect the real-time temperature on the surface of a lithium-ion battery cell (3) and make the following judgments based on the real-time temperature: When the real-time temperature is lower than the preset temperature range, control the external light guide assembly (4) to be enabled to irradiate the photothermal phase change material, and utilize the characteristic of the photothermal phase change material absorbing light and generating heat to heat the lithium-ion battery cell (3); and when the user requests rapid temperature increase, control the thermoelectric module (6) to be enabled in the heating mode, and transfer the additional heat generated by the thermoelectric module (6) to the heat pipe (5) through the first working surface, and then transfer it to the lithium-ion battery cell (3); When the real-time temperature is maintained within the preset temperature range, the external light guide component (4) is controlled to switch to the idle state, so as to implement passive temperature control adjustment for the lithium-ion battery cell (3) by utilizing the phase change process of the photothermal phase change material itself; at the same time, the thermoelectric module (6) is controlled to switch to the idle state; When the real-time temperature is higher than the preset temperature range, the external light guide component (4) is controlled to switch to the idle state; at the same time, the thermoelectric module (6) is controlled to enable the refrigeration mode, and the battery heat is transferred to the first working surface of the thermoelectric module (6) through the heat pipe (5) in contact with the lithium-ion battery cell (3), thereby implementing refrigeration.

Images