A method and apparatus for full-temperature-range battery thermal management based on hydrated salt composite materials

Abstract

This invention provides a full-temperature-range battery thermal management method and apparatus based on hydrated salt composite materials. The composite material is disposed on the outside of the battery, and the composite material includes a porous dielectric framework and hydrated salts. The battery thermal management method includes the following steps: S1, preheating before charging and discharging: before charging and discharging the battery, the ambient temperature T is preheated. 环 Perform the test, if T 环 If T < T0, then the battery is preheated; if T < T0, then the battery is preheated. 环 If T0 is greater than or equal to T0, then charging and discharging can proceed directly; S2, temperature control during charging and discharging: during the charging and discharging process, when the battery temperature T... 电池 When the battery is within its optimal operating temperature range T0 to T1, medium-temperature temperature control is applied; when T... 电池 When the temperature is greater than T1, the battery is cooled by absorbing heat at high temperature. The battery thermal management method and device of the present invention integrate heating and cooling functions by preheating before charging and discharging, controlling the temperature at medium temperature during charging and discharging, and absorbing heat at high temperature to cool down. It has multi-stage temperature control capability and realizes thermal management of the battery in the whole temperature range.

Description

Technical Field

[0001] This invention relates to the field of battery thermal management and thermal safety technology, and in particular to a full-temperature-range battery thermal management method and device based on hydrated salt composite materials. Background Technology

[0002] Lithium-ion batteries are the most widely used batteries in electric vehicles and energy storage systems, and their efficiency, safety performance, and cycle life have received widespread attention. Typically, lithium-ion batteries are extremely sensitive to operating temperature, with an optimal operating temperature between 15 and 35°C. Temperatures that are too low or too high can lead to decreased battery performance, capacity loss, and even threaten battery safety; high temperatures can also trigger thermal runaway. Furthermore, uneven temperature distribution within the lithium-ion battery can further reduce battery capacity and affect cycle life. Therefore, an efficient battery thermal management system is a key means to ensure the long-term, safe, and efficient operation of lithium-ion batteries.

[0003] In existing technologies, the thermal management systems of power batteries and energy storage batteries are structurally similar, currently mainly including air cooling, liquid cooling, phase change material (PCM) cooling, and heat pipe cooling. Among these, PCM cooling, as a passive cooling technology, requires no additional power supply and has a simple and compact system, thus attracting increasing attention. Among PCM materials, hydrated salt materials, as inorganic PCM materials, offer advantages over commonly used organic PCM materials, such as good flame retardancy, lower price, and higher latent heat. As a thermochemical adsorption material, hydrated salt materials offer advantages in thermochemical heat storage technology, including high heat storage density, small heat storage volume, low heat loss, and environmental friendliness. Therefore, hydrated salt materials possess both phase change heat storage and thermochemical heat storage capabilities, enabling efficient heat storage and release, meeting the thermal management and thermal safety protection requirements of lithium-ion batteries.

[0004] Currently, through exploration, various methods and systems for thermal management of batteries using phase change material cooling technology have been proposed:

[0005] For example, Chinese patent application CN113097599A discloses a passive battery thermal regulator based on supercooled phase change material, including a phase change module and a thermal switch device. The phase change module is composed of a phase change material with a certain degree of supercooling. It can realize passive battery temperature management and control by combining the characteristics of volume change, freezing point and melting point in the charge and discharge process of the phase change material. The function of the supercooled phase change material is: in addition to providing power for the opening and closing process of the thermal switch device based on volume change, it also melts at high temperature to absorb the heat generated by the battery to maintain the battery temperature from rising further, and freezes at low temperature to release heat to the battery and increase the battery temperature, thereby further controlling the battery operating temperature based on the thermal switch device.

[0006] Chinese patent application CN110551485A discloses a hydrated salt phase change energy storage material and its preparation method, as well as a battery thermal management system. The energy storage material is made from the following raw materials: 40-90% hydrated salt, 0-15% temperature regulator, 1-5% nucleating agent, 0-2% thickener, and 9-38% porous adsorption matrix. The preparation method includes the following steps: (1) mixing the temperature regulator and hydrated salt evenly to obtain a mixture; (2) heating to melt the mixture; (3) stirring the mixture obtained in step (2) evenly to obtain a molten mixture; (4) adding the thickener and nucleating agent to the molten mixture and stirring continuously until homogeneous; (5) adding the homogeneous mixture obtained in step (4) to the porous adsorption matrix and stirring continuously until the mixture is completely adsorbed into the porous matrix; (6) cooling and solidifying. This invention has dual-temperature range control capability, realizing temperature regulation of the battery pack within the entire temperature range, improving the performance and lifespan of the battery pack while enhancing its safety.

[0007] Chinese patent application CN112552880A discloses a phase change energy storage material made from the following raw materials: inorganic hydrated salt, anti-overcooling agent, nucleating agent, sodium polyacrylate, and porous adsorption matrix. The process includes the following steps: placing the inorganic hydrated salt and anti-overcooling agent together and stirring to obtain a hydrated inorganic salt solution. This phase change energy storage material and thermal management system, by possessing dual-temperature-range temperature control capabilities, overcomes the limitation of single-temperature control in phase change paraffin, enabling more comprehensive temperature regulation of the battery pack. Anti-overcooling agent and sodium polyacrylate are added during its preparation process. The anti-overcooling agent effectively prevents overcooling during the phase change process of the hydrated inorganic salt phase change material, while sodium polyacrylate has a thickening effect, ensuring the homogeneity of the phase change material after multiple cycles and effectively preventing phase separation and stratification.

[0008] Chinese patent application CN113372884A discloses an expanded graphite composite inorganic hydrated salt phase change material and its preparation method, relating to the field of heat exchange or heat storage materials. The preparation method comprises the following raw materials: anhydrous ethanol, a surfactant, expanded graphite, and an inorganic hydrated salt. Specifically, the method involves first dissolving the surfactant in anhydrous ethanol, then modifying the hydrophilicity of the expanded graphite using the surfactant's hydrophilic and lipophilic properties, and finally encapsulating the inorganic hydrated salt in the modified expanded graphite using a vacuum ultrasonic method. The overall preparation method is simple, highly efficient in encapsulation, convenient in application, and safe to operate, making it suitable for large-scale industrial production. The resulting composite phase change energy storage material has a high heat storage capacity and can be widely used in solar energy storage, building temperature control, power battery thermal management, heating, industrial waste heat utilization, and electronic device heat dissipation.

[0009] However, existing methods and systems for thermal management of batteries using phase change material cooling technology typically have the following drawbacks:

[0010] First, when using phase change material cooling technology alone for battery thermal management, there is usually a limited temperature control range, which makes it impossible to effectively manage the battery thermally and suppress thermal runaway across the entire temperature range. However, in actual use, batteries are often in environments with low temperatures below 0°C or even -10°C and high temperatures above 40°C or even 60°C. These ambient temperatures are far beyond the normal operating range of the battery, but phase change material cooling technology cannot effectively manage the battery thermally.

[0011] Second, in order to overcome the shortcomings of phase change material cooling technology, coupling phase change material cooling technology with other cooling methods will greatly increase the complexity and cost of the system.

[0012] Third, poor temperature uniformity between batteries can also reduce battery capacity and affect cycle life. Summary of the Invention

[0013] This invention designs a full-temperature-range battery thermal management method and device based on hydrated salt composite materials to achieve the purpose of full-temperature-range thermal management of batteries.

[0014] To address the aforementioned problems, this invention discloses a full-temperature-range battery thermal management method based on a hydrated salt composite material. The composite material is disposed on the outside of the battery undergoing thermal management. The composite material comprises a porous dielectric framework and hydrated salts filled within the porous dielectric framework. The optimal operating temperature range of the battery is T0 to T1, where T0 is the lower limit of the optimal operating temperature range and T1 is the upper limit of the optimal operating temperature range. The full-temperature-range battery thermal management method includes the following steps:

[0015] S1, Preheating before charging and discharging: Before the battery is charged or discharged, the ambient temperature T is preheated. 环 Perform the test, if T 环 If T < T0, then the battery is preheated; if T < T0, then the battery is preheated. 环 If T0 is greater than or equal to T0, then the battery is directly charged and discharged.

[0016] S2, Temperature control during charging and discharging: During the charging and discharging process of the battery, when the battery temperature T... 电池 When the battery is within its optimal operating temperature range T0 to T1, medium-temperature temperature control is applied; when the battery temperature T... 电池 When the temperature is greater than T1, the battery is cooled by absorbing heat at high temperature.

[0017] Furthermore, step S1 includes:

[0018] S101, before the battery is charged or discharged, the ambient temperature T is monitored.环 Conduct testing;

[0019] S102, compared to ambient temperature T 环 The relative size of T0, if T 环 If T < T0, then continue with step S103. 环 If T0 is greater than or equal to T0, then the battery is directly charged and discharged.

[0020] S103, Obtain the first preset threshold T 阈1 Compared with the ambient temperature T 环 and the first preset threshold T 阈1 The relative size of T 环 <T 阈1 If T is low temperature, the battery will be preheated at ultra-low temperature; if T 阈1 ≤T 环 Then the battery is preheated at a low temperature.

[0021] Furthermore, step S103 also includes:

[0022] When T 阈1 ≤T 环 At that time, obtain the second preset threshold T. 阈2 , among which, T 阈1 <T 阈2 <T0; compared to ambient temperature T 环 Second preset threshold T 阈2 The relative size of T 阈1 ≤T 环 <T 阈2 Then the battery is preheated at a low temperature.

[0023] Furthermore, step S103 also includes:

[0024] If T 环 <T 阈1 If the battery is subjected to ultra-low temperature preheating, then the battery temperature T is controlled. 电池 Monitoring is conducted when the electrical T 阈2 ≤T 电池 At this point, stop the ultra-low temperature preheating of the battery and switch to low temperature preheating until the battery temperature T is reached. 电池 The lower limit temperature T0 of the optimal operating temperature range.

[0025] Furthermore, in step S103, the ultra-low temperature preheating method involves applying an electric current to the porous medium skeleton to convert electrical energy into heat energy through the Joule effect to preheat the battery in the ultra-low temperature environment; the low temperature preheating method involves introducing air into the composite material, where the hydrated salts in the composite material adsorb water vapor from the air and release heat to preheat the battery in the low temperature environment.

[0026] Furthermore, step S2 includes:

[0027] S201, during the charging and discharging process of the battery, the battery temperature T is monitored. 电池 Monitoring is performed when the battery temperature T 电池 When the battery is within its optimal operating temperature range T0 to T1, medium-temperature temperature control is applied; when the battery temperature T... 电池 When T1 is reached, step S202 is executed to cool the battery by absorbing heat at high temperature.

[0028] S202, obtain the preset temperature value T2, where T1 < T2, and determine the battery temperature T. 电池 The relative magnitude of the preset temperature value T2, when T1 < T 电池 When T < T2, the battery is cooled by the heat absorption of hydrated salt dehydration and the heat absorption of water vapor escape; when T < T < T2, the battery is cooled by the heat absorption of hydrated salt dehydration and water vapor escape. 电池 When the temperature is greater than T2, the battery is cooled by endothermic heat absorption through high-temperature phase change of anhydrous salt or endothermic heat absorption through high-temperature thermochemical decomposition of anhydrous salt.

[0029] Furthermore, in step S2, the intermediate temperature control is achieved through a reversible phase transition of the hydrated salt.

[0030] A full-temperature-range battery thermal management device based on hydrated salt composite materials, wherein the full-temperature-range battery thermal management device employs the aforementioned full-temperature-range battery thermal management method to perform thermal management on the battery, and the battery thermal management device comprises:

[0031] A battery pack consisting of several batteries connected in series or in parallel;

[0032] A composite material wrapped around the outside of a battery, the composite material comprising hydrated salts and a porous dielectric framework, wherein the hydrated salts fill the porous dielectric framework;

[0033] The battery pack is housed in a cabinet, and the composite material is connected to a power supply device that can apply current to the composite material.

[0034] Furthermore, the hydrated salt is one or more of sodium sulfate decahydrate, sodium acetate trihydrate, and sodium thiosulfate pentahydrate; the porous media framework is expanded graphite or foamed metal.

[0035] Furthermore, adjustable air vents are provided on the cabinet.

[0036] The full-temperature-range battery thermal management method and device based on hydrated salt composite materials described in this application have the following advantages:

[0037] First, compared with existing phase change material thermal management methods, this application integrates heating and cooling functions through ultra-low temperature preheating and low temperature preheating before charging and discharging, as well as medium temperature control and high temperature heat absorption and cooling during charging and discharging. This enables the hydrated salt composite material to have multi-stage temperature control capabilities, and it has high phase change enthalpy and chemical decomposition enthalpy, high energy density, and can effectively balance thermal management and thermal runaway protection. It achieves battery thermal management within the entire temperature range, which is used to maintain the battery's operating temperature within a reasonable range under different operating conditions and external environmental conditions, suppress thermal runaway, and ensure its safe operation. The full-temperature-range battery thermal management method and device have a wider range of battery thermal management temperature and stronger applicability.

[0038] Second, compared with traditional air cooling and liquid cooling methods, the battery thermal management method and device described in this application have a simple and compact structure, low cost, and no additional power supply is required during the high-temperature heat absorption and cooling stage. It can effectively manage the battery thermally, suppress thermal runaway, and efficiently store and release heat across the entire temperature range.

[0039] Third, compared with existing thermal management systems for hydrated salt materials, the composite material described in this application can take into account both low-temperature preheating and high-temperature cooling. It takes into account the battery temperature changes under different external environments and operating conditions. The rate of heat and water vapor entering and leaving the cabinet is controlled by the size of the vent area on the cabinet, thereby adjusting the temperature of the battery pack and the adsorption and desorption process of hydrated salt.

[0040] Fifth, based on traditional porous media and hydrated salt composite materials, this application utilizes the good electrical and thermal conductivity of porous media to achieve efficient electrothermal conversion through the Joule effect, thus effectively preheating the battery in ultra-low temperature environments.

[0041] Sixth, by utilizing the heat conversion of the supercooled phase change or phase change process of hydrated salt materials, the battery can be maintained within the optimal operating temperature range, and the temperature uniformity between batteries can be improved. At the same time, as an inorganic material, hydrated salt is inexpensive, stable, and non-flammable, which can effectively improve the economy and safety of battery modules.

[0042] Seventh, high-temperature heat absorption is achieved through methods such as dehydration and water vapor release of hydrated salts, high-temperature phase change of anhydrous salts, and high-temperature thermochemical decomposition of anhydrous salts, thereby effectively cooling the battery and suppressing the spread of battery thermal runaway. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the battery thermal management device described in this invention;

[0044] Figure 2 This is a cross-sectional structural diagram of the battery thermal management device described in this invention;

[0045] Figure 3 This is a schematic diagram of the adsorption-desorption process in the battery thermal management device of the present invention;

[0046] Figure 4 This is a flowchart of the battery thermal management method described in this invention;

[0047] Figure 5 This is a schematic diagram of the heat storage process across the entire temperature range of the composite material composed of sodium sulfate decahydrate and expanded graphite in Example 1 of the present invention.

[0048] Explanation of reference numerals in the attached figures:

[0049] 1. Cabinet; 2. Composite material; 3. Battery. Detailed Implementation

[0050] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0051] like Figures 1-5 As shown, a full-temperature-range battery thermal management method based on hydrated salt composite material is disclosed. The composite material is disposed on the outside of the battery for thermal management. The composite material comprises a porous dielectric framework and hydrated salts filled within the porous dielectric framework. The optimal operating temperature range of the battery is T0 to T1, where T0 is the lower limit of the optimal operating temperature range and T1 is the upper limit of the optimal operating temperature range. The full-temperature-range battery thermal management method includes the following steps:

[0052] S1, Preheating before charging and discharging: Before the battery is charged or discharged, the ambient temperature T is preheated. 环 Perform the test, if T 环 If T < T0, then the battery is preheated; if T < T0, then the battery is preheated. 环 If T0 is greater than or equal to T0, then the battery is directly charged and discharged.

[0053] S2, Temperature control during charging and discharging: During the charging and discharging process of the battery, when the battery temperature T... 电池 When the battery is within its optimal operating temperature range T0 to T1, medium-temperature temperature control is applied; when the battery temperature T... 电池 When the temperature is greater than T1, the battery is cooled by absorbing heat at high temperature.

[0054] Furthermore, the values ​​of T0 and T1 can be determined experimentally.

[0055] As some embodiments of this application, T0 is 15°C and T1 is 35°C.

[0056] Furthermore, step S1 includes:

[0057] S101, before the battery is charged or discharged, the ambient temperature T is monitored. 环 Conduct testing;

[0058] S102, compared to ambient temperature T 环 The relative size of T0, if T 环 If T < T0, then continue with step S103. 环 If T0 is greater than or equal to T0, then the battery is directly charged and discharged.

[0059] S103, Obtain the first preset threshold T 阈1 Compared with the ambient temperature T 环 and the first preset threshold T 阈1 The relative size of T 环 <T 阈1 If T is low temperature, the battery will be preheated at ultra-low temperature; if T 阈1 ≤T 环 Then the battery is preheated at a low temperature.

[0060] Furthermore, step S103 also includes:

[0061] When T 阈1 ≤T 环 At that time, obtain the second preset threshold T. 阈2 , among which, T 阈1 <T 阈2 <T0; compared to ambient temperature T 环 Second preset threshold T 阈2 The relative size of T 阈1 ≤T 环 <T 阈2 If T is low temperature preheating, then the battery will be preheated; if T 阈2 ≤T 环 Then, the battery can be preheated at low temperature or directly charged and discharged as needed.

[0062] Wherein, the T 阈1 and T 阈2 The value of can be determined experimentally. As some embodiments of this application, the value of T... 阈1 The temperature is -10℃, and the T 阈2 The temperature is 5℃.

[0063] Furthermore, step S103 also includes:

[0064] If T 环 <T 阈1 If the battery is subjected to ultra-low temperature preheating, then the battery temperature T is controlled. 电池 Monitoring is conducted when the electrical T 阈2 ≤T 电池At this point, stop the ultra-low temperature preheating of the battery and switch to low temperature preheating until the battery temperature T is reached. 电池 The lower limit temperature T0 of the optimal operating temperature range.

[0065] Preferably, in step S103, the ultra-low temperature preheating method is to apply an electric current to the porous medium skeleton, and convert electrical energy into heat energy through the Joule effect to preheat the battery in the ultra-low temperature environment; the low temperature preheating method is to introduce air into the composite material, and some of the hydrated salts in the composite material adsorb water vapor in the air and release heat to preheat the battery in the low temperature environment.

[0066] As some embodiments of this application, when applying current to the porous dielectric framework, the amount of heat generated by the Joule effect can be controlled by controlling the magnitude of the applied current, thereby controlling the heating rate of the battery and the battery temperature T during the cryogenic preheating process. 电池 The value of .

[0067] Furthermore, in step S2, the battery temperature T 电池 When the battery is within the optimal operating temperature range T0 to T1, it refers to the battery temperature T. 电池 Satisfying T0≤T 电池 ≤T1 condition.

[0068] Furthermore, in step S2, the high-temperature endothermic reaction refers to the phenomenon where the hydrated salt material loses water molecules to form anhydrous salt under high-temperature conditions, and the anhydrous salt further undergoes phase transition and chemical decomposition. During use, when the battery temperature T... 电池 The temperature continues to rise rapidly, reaching the dehydration temperature of the hydrated salt material. Because the hydrated salt has a high chemical decomposition enthalpy, it will generate anhydrous salt and absorb a large amount of heat during dehydration, which can effectively absorb the heat of the battery. At the same time, the water vapor generated by the dehydration of the hydrated salt will escape from the porous medium framework, further carrying away the heat generated by the battery. If the temperature continues to rise, reaching the phase transition or even chemical decomposition temperature of the anhydrous salt, the anhydrous salt will undergo a phase transition or chemical decomposition reaction and absorb a large amount of heat, thereby inhibiting the occurrence and spread of thermal runaway.

[0069] Furthermore, step S2 includes:

[0070] S201, during the charging and discharging process of the battery, the battery temperature T is monitored. 电池 Monitoring is performed when the battery temperature T 电池 When the battery is within its optimal operating temperature range T0 to T1, medium-temperature temperature control is applied; when the battery temperature T... 电池 When T1 is reached, step S202 is executed to cool the battery by absorbing heat at high temperature.

[0071] S202, obtain the preset temperature value T2, where T1 < T2, and determine the battery temperature T. 电池 The relative magnitude of the preset temperature value T2, when T1 < T 电池 When T < T2, the battery is cooled by the heat absorption of hydrated salt dehydration and the heat absorption of water vapor escape; when T < T < T2, the battery is cooled by the heat absorption of hydrated salt dehydration and water vapor escape. 电池 When the temperature is greater than T2, the battery is cooled by endothermic heat absorption through high-temperature phase change of anhydrous salt or endothermic heat absorption through high-temperature thermochemical decomposition of anhydrous salt.

[0072] Specifically, in step S202, as the battery temperature T... 电池 The temperature rises when the battery temperature T 电池 When the temperature exceeds T1, the composite material reaches the desorption temperature of the hydrated salt. The hydrated salt dehydrates into anhydrous salt, absorbing a large amount of heat. Simultaneously, the water vapor generated during dehydration escapes from the porous medium framework, further carrying away the heat generated by the battery, thereby suppressing the spread of battery thermal runaway. This achieves the purpose of cooling the battery through the heat absorption of high-temperature dehydration of the hydrated salt and the heat absorption of water vapor escape. Afterwards, as the battery temperature T... 电池 As the temperature continues to rise, when the battery temperature T... 电池 When the temperature exceeds T2, the temperature of the composite material reaches the melting point or chemical decomposition temperature of the anhydrous salt. At this point, the battery temperature T is effectively reduced either by the anhydrous salt in the composite material melting and absorbing heat, or by the anhydrous salt undergoing a chemical decomposition reaction and absorbing a large amount of heat. 电池 This suppresses the spread of thermal runaway and achieves the goal of cooling the battery through the high-temperature phase change heat absorption of anhydrous salt. Therefore, the settings of T1 and T2 need to be based on the dehydration temperature of hydrated salt, the melting point of anhydrous salt, and the chemical decomposition temperature of anhydrous salt.

[0073] Furthermore, in step S2, the intermediate temperature control is achieved through a reversible phase change of the hydrated salt, such as a normal phase change or a supercooled phase change. The supercooled phase change is a phenomenon where the solidification point of the solid-liquid phase change material is lower than its melting point; the resulting temperature difference is called the degree of supercooling. Specifically, within the optimal operating temperature range T0 to T1, there exists an optimal operating temperature where the battery operates with the highest efficiency and the least adverse effects on the battery. During battery charging and discharging, as the battery temperature T... 电池 The decrease, such as when the battery temperature T 电池 Below the optimal operating temperature, the composite material begins to solidify and release heat as it reaches near the freezing point of the hydrated salt material, causing the battery temperature T to rise. 电池 Increase; conversely, decrease as battery temperature T decreases. 电池 The temperature rises, such as when the battery temperature T 电池 When the optimal operating temperature is exceeded, the hydrated salt material reaches near its melting point, and the hydrated salt begins to melt and absorb heat, causing the battery temperature T to rise. 电池 The temperature decreases, thereby reducing the battery temperature T through the reversible phase transition of the hydrated salt. 电池It always operates within the optimal operating temperature range of T0 to T1. Therefore, the phase transition point of the hydrated salt should be located between T0 and T1.

[0074] During battery operation, regardless of fluctuations in ambient temperature or changes in battery discharge rate, the heating or cooling environment provided by the phase change hydrated salt material can maintain the battery temperature T. 电池 It always maintains the optimal operating temperature range, while further improving the temperature uniformity between batteries.

[0075] In addition, this application also provides a full-temperature-range battery thermal management device based on hydrated salt composite material, wherein the full-temperature-range battery thermal management device uses the above-mentioned full-temperature-range battery thermal management method to perform thermal management on the battery.

[0076] Specifically, the full-temperature-range battery thermal management device based on hydrated salt composite materials includes:

[0077] A battery pack consisting of several batteries connected in series or in parallel;

[0078] The composite material 2, which is wrapped around the outside of the battery 3, comprises hydrated salt and a porous medium skeleton, wherein the hydrated salt is filled in the porous medium skeleton; the heat generated by the battery 3 is initially absorbed by the composite material 2 and then dissipated into the environment.

[0079] The battery pack is installed in the cabinet 1, and the composite material 2 is connected to the power supply device, which can apply current to the composite material 2.

[0080] Preferably, the composite material 2 is connected to a power supply device, which is capable of applying current to the porous dielectric skeleton in the composite material 2.

[0081] As some embodiments of this application, the battery 3 is a lithium-ion battery.

[0082] Furthermore, the hydrated salt material includes, but is not limited to, sodium sulfate decahydrate, sodium acetate trihydrate, and sodium thiosulfate pentahydrate with a purity of 99% or higher. The hydrated salt material can absorb water and release heat or dehydrate and absorb heat under certain humidity and temperature conditions, and undergo phase change and chemical decomposition under certain temperature conditions to absorb a large amount of heat.

[0083] Furthermore, the porous medium framework includes, but is not limited to, porous materials such as expanded graphite or foamed metal. Porous expanded graphite and foamed metal have advantages such as good thermal conductivity, good electrical conductivity, high porosity, and large specific surface area. When used in this application, they can not only increase the thermal conductivity of hydrated salt materials by several times, enhancing their heat exchange performance, but also stabilize the overall structure of the composite material, making it macroscopically solid and providing a certain degree of support. In addition, they can also ensure the uniform distribution of hydrated salt materials, preventing leakage.

[0084] Preferably, the composite material is composed of hydrated salt material and porous media material in a certain proportion.

[0085] It should be noted that the method for preparing the composite material by combining hydrated salt materials with porous media materials has been disclosed in the prior art and will not be described in detail here.

[0086] Furthermore, the composite material also includes a thickener used to inhibit phase separation of the hydrated salt material.

[0087] As some embodiments of this application, the thickener includes, but is not limited to, one or more of sodium carboxymethyl cellulose, polyacrylamide, and activated clay. The use of the thickener can increase the viscosity of the solution, so that the hydrated salt material is suspended in the solution after melting and does not separate from the solution, while not affecting the phase change and dehydration of the hydrated salt material, thereby inhibiting phase separation.

[0088] Furthermore, the composite material also includes a nucleating agent used to suppress the supercooling of the hydrated salt material.

[0089] Furthermore, the cabinet 1 is a cabinet with controllable boundaries.

[0090] Specifically, adjustable vents are provided on the cabinet 1. By adjusting the size of the vent openings, the boundaries of the cabinet 1 can be adjusted, thereby regulating the rate of heat and water vapor entering and exiting the cabinet 1.

[0091] As some embodiments of this application, such as Figure 1 As shown, one side wall of the cabinet 1 is configured to be rotatably opened, forming an adjustable-area vent on the cabinet 1 by opening this side wall. Specifically, when it is necessary to increase the opening area of ​​the vent, this can be achieved by increasing the opening range of the side wall; conversely, when it is necessary to decrease the opening area of ​​the vent, this can be achieved by decreasing the opening range of the side wall.

[0092] Preferably, the rotatable sidewall is arranged vertically on one side of the cabinet 1.

[0093] During use, the rate at which heat and water vapor enter and exit the cabinet 1 can be adjusted by changing the size of the opening area of ​​the pores, thereby regulating the temperature of the battery pack and the adsorption and desorption process of hydrated salts.

[0094] Specifically, during the full-temperature-range battery thermal management process, when preheating battery 3 at low temperatures, the vents on the cabinet 1 can be opened to allow air to enter the cabinet 1, enabling the hydrated salt material to absorb water vapor and release heat, thus providing conditions for battery preheating in lower temperature environments. After preheating, when the battery pack's charge / discharge rate is low, the anhydrous salt can continue to absorb water; if the battery pack's charge / discharge rate is high and the battery pack temperature rises significantly, the hydrated salt will absorb heat at high temperatures to activate its cooling function, initiating a new stage of thermal management. Furthermore, when preheating the porous dielectric framework at extremely low temperatures using electricity, the vents on the cabinet 1 can be closed to reduce heat loss and improve the preheating efficiency of battery 3. At battery temperature T... 电池 Once the optimal operating temperature range is exceeded, the vents on cabinet 1 open to dissipate the heat generated by battery 3 into the external environment. Furthermore, the vents on cabinet 1 need to be closed promptly after the hydrated salt has dehydrated. When the battery pack restarts operation, the vents are opened in advance to allow water vapor in the air to enter cabinet 1, where the anhydrous salt absorbs water to become hydrated salt, releasing heat for low-temperature preheating.

[0095] To address the shortcomings of existing battery thermal management systems in terms of their lack of specificity and applicability to different battery operating states and ambient temperatures—for example, winter temperatures in northern my country can drop to -35°C, necessitating a preheating system for ultra-low temperature environments; simultaneously, the heat generated during battery charging and discharging leads to temperature rise and uneven temperature distribution among batteries, requiring a temperature control system for normal battery operation; furthermore, external impacts or internal short circuits in the battery pack can trigger a series of chain reactions such as thermal runaway, necessitating external cooling measures to suppress the spread of thermal runaway. However, directly combining systems with different functions would result in low efficiency of full-temperature-range thermal management and a more complex device. Therefore, the full-temperature-range battery thermal management method and device based on hydrated salt composite materials described in this application have the following advantages:

[0096] Secondly, compared with existing phase change material thermal management methods, this application integrates heating and cooling functions through ultra-low temperature preheating and low temperature preheating before charging and discharging, as well as medium temperature control and high temperature heat absorption and cooling during charging and discharging. This enables the hydrated salt composite material to have multi-stage temperature control capabilities, and it has high phase change enthalpy and chemical decomposition enthalpy, high energy density, and can effectively balance thermal management and thermal runaway protection. It achieves battery thermal management within the entire temperature range, which is used to maintain the battery's operating temperature within a reasonable range under different operating conditions and external environmental conditions, suppress thermal runaway, and ensure its safe operation. The full-temperature-range battery thermal management method and device have a wider range of battery thermal management temperature and stronger applicability.

[0097] Second, compared with traditional air cooling and liquid cooling methods, the battery thermal management method and device described in this application have a simple and compact structure, low cost, and no additional power supply is required during the high-temperature heat absorption and cooling stage. It can effectively manage the battery thermally, suppress thermal runaway, and efficiently store and release heat across the entire temperature range.

[0098] Third, compared with existing thermal management systems for hydrated salt materials, the composite material described in this application can take into account both low-temperature preheating and high-temperature cooling. It takes into account the battery temperature changes under different external environments and operating conditions. The rate of heat and water vapor entering and leaving the cabinet is controlled by the size of the vent area on the cabinet, thereby adjusting the temperature of the battery pack and the adsorption and desorption process of hydrated salt.

[0099] Fifth, based on traditional porous media and hydrated salt composite materials, this application utilizes the good electrical and thermal conductivity of porous media to achieve efficient electrothermal conversion through the Joule effect, thus effectively preheating the battery in ultra-low temperature environments.

[0100] Sixth, by utilizing the heat conversion of the supercooled phase change or phase change process of hydrated salt materials, the battery can be maintained within the optimal operating temperature range, and the temperature uniformity between batteries can be improved. At the same time, as an inorganic material, hydrated salt is inexpensive, stable, and non-flammable, which can effectively improve the economy and safety of battery modules.

[0101] Seventh, high-temperature heat absorption is achieved through methods such as dehydration and water vapor release of hydrated salts, high-temperature phase change of anhydrous salts, and high-temperature thermochemical decomposition of anhydrous salts, thereby effectively cooling the battery and suppressing the spread of battery thermal runaway.

[0102] The following specific embodiments illustrate the full-temperature-range battery thermal management method and apparatus based on hydrated salt composite materials described in this application:

[0103] Example 1

[0104] A full-temperature-range battery thermal management device based on hydrated salt composite material, the battery thermal management device includes a cabinet, a composite material composed of sodium sulfate decahydrate and expanded graphite, and a lithium-ion battery pack. The expanded graphite and sodium sulfate decahydrate are prepared into a composite material in a ratio of 15:85. The performance parameters of the composite material are shown in Table 1 below. The composite material is wrapped around the surface of the lithium-ion single cell with a certain thickness. The lithium-ion battery pack, composed of several single cells connected in series or in parallel, is placed in a cuboid cabinet with controllable boundaries.

[0105] The battery thermal management device operates according to the aforementioned battery thermal management method: When the battery is below -10°C, an electric current is applied to the expanded graphite skeleton to preheat the battery in the ultra-low temperature environment through the Joule effect of electro-thermal conversion; when the battery is below 5°C, all vents on the cabinet are opened to allow air in, and the hydrated salt material adsorbs water vapor from the air and releases heat, preheating the battery in the lower temperature environment to the optimal operating temperature. During battery charging and discharging, if the temperature exceeds the optimal operating temperature, it begins to melt and absorb heat due to reaching the melting point of sodium sulfate decahydrate (32.4°C), causing the battery temperature to drop; if the temperature is below the optimal operating temperature, it begins to solidify and release heat due to reaching the freezing point of sodium sulfate decahydrate (20°C), causing the battery temperature to rise. During battery operation, regardless of fluctuations in the external ambient temperature or changes in operating conditions such as the discharge rate, the heating or cooling environment provided by the supercooled phase change of sodium sulfate decahydrate ensures that the battery temperature is always maintained within the optimal operating temperature range, while further improving the temperature uniformity between batteries. When the battery temperature continues to rise rapidly and reaches the dehydration temperature of about 70°C, sodium sulfate decahydrate has a high chemical decomposition enthalpy. During dehydration, sodium sulfate is generated and absorbs a large amount of heat, which can effectively absorb the heat of the battery. At the same time, the water vapor generated during dehydration will escape from the expanded graphite and further carry away the heat generated by the battery.

[0106] Figure 5 The thermal storage process of the composite material composed of sodium sulfate decahydrate and expanded graphite in Example 1 is shown across the entire temperature range.

[0107] As shown in Table 1, compared with the traditional phase change material paraffin, the sodium sulfate decahydrate-expanded graphite composite material used in this embodiment has multi-stage temperature control capability and a wider temperature control range, which can take into account preheating at low temperature, temperature control in the medium temperature range and thermal safety protection in the high temperature range; at the same time, it has a higher phase change enthalpy and chemical decomposition enthalpy, which can absorb more heat generated by the battery and improve the temperature uniformity between batteries.

[0108] Example 2

[0109] A full-temperature-range battery thermal management device based on a hydrated salt composite material is disclosed. The device comprises a cabinet, a composite material composed of sodium sulfate decahydrate and expanded graphite, and a lithium-ion battery pack. The expanded graphite and sodium sulfate decahydrate are prepared as a composite material in a 15:85 ratio. The performance parameters of the composite material are shown in Table 1 below. The structure of the battery thermal management device shown in Example 2 is basically the same as that in Example 1, except that the device in Example 2 has no external wires, and the composite material is not connected to a power supply device, making it suitable for applications where the ambient temperature is almost always above zero.

[0110] The battery thermal management device is controlled to operate according to the above-described battery thermal management method: First, sodium sulfate decahydrate adsorbs water vapor in the air and releases heat to preheat the battery in a low-temperature environment; then the battery enters the working state, and the supercooling phase change of sodium sulfate decahydrate keeps the battery temperature in the optimal working temperature range; as the battery working temperature rises, sodium sulfate decahydrate dehydrate dehydrates and releases heat at 70°C, initially suppressing thermal runaway.

[0111] Example 3

[0112] A full-temperature-range battery thermal management device based on a hydrated salt composite material is disclosed. The device comprises a cabinet, a composite material composed of sodium acetate trihydrate and expanded graphite, and a lithium-ion battery pack. The expanded graphite and sodium acetate trihydrate are prepared as a composite material in a 10:90 ratio. The performance parameters of the composite material are shown in Table 1 below. The battery thermal management device shown in Example 3 has the same structure as that in Example 1, except that the hydrated salt material is sodium acetate trihydrate and a nucleating agent to inhibit overcooling, which is applied to scenarios involving continuous high-rate charging and discharging of the battery.

[0113] The battery thermal management device operates according to the aforementioned battery thermal management method: When the battery is below -10°C, an electric current is applied to the expanded graphite skeleton to preheat the battery in the ultra-low temperature environment through the Joule effect of electro-thermal conversion; when the battery is below 5°C, the vents on the cabinet are fully opened to allow air in, and the hydrated salt material adsorbs water vapor from the air and releases heat, preheating the battery in the lower temperature environment to the optimal operating temperature. During battery charging and discharging, if the temperature exceeds the optimal operating temperature, it begins to melt and absorb heat due to reaching the melting point of sodium acetate trihydrate (58°C), causing the battery temperature to drop; if the temperature is below the optimal operating temperature, it begins to solidify and release heat due to reaching the freezing point of sodium acetate trihydrate, causing the battery temperature to rise. When the battery temperature continues to rise rapidly, reaching the dehydration temperature of sodium acetate trihydrate (around 106°C), the sodium acetate trihydrate absorbs a large amount of heat during dehydration, initially suppressing thermal runaway; when the battery temperature rises further, the sodium acetate reaches its melting point of 304°C and melts and absorbs heat, suppressing the spread of thermal runaway.

[0114] Example 4

[0115] A full-temperature-range battery thermal management device based on a hydrated salt composite material is disclosed. The device comprises a cabinet, a composite material composed of sodium thiosulfate pentahydrate and expanded graphite, and a lithium-ion battery pack. The expanded graphite and sodium thiosulfate pentahydrate are prepared as a composite material in a 20:80 ratio. The performance parameters of the composite material are shown in Table 1 below. The battery thermal management device shown in Example 4 has the same structure as that in Example 1, except that the hydrated salt material is sodium thiosulfate pentahydrate, which is applied to scenarios where the battery is subjected to continuous high-rate charging and discharging and is prone to thermal runaway.

[0116] The battery thermal management device operates according to the aforementioned battery thermal management method: When the battery is below -10°C, an electric current is applied to the expanded graphite skeleton to preheat the battery in the ultra-low temperature environment through the Joule effect of electro-thermal conversion; when the battery is below 5°C, all vents on the cabinet are opened to allow air in, and the hydrated salt material adsorbs water vapor from the air and releases heat, preheating the battery in the lower temperature environment to the optimal operating temperature. During battery charging and discharging, if the temperature exceeds the optimal operating temperature, it begins to melt and absorb heat because it reaches the melting point of sodium thiosulfate pentahydrate (48.9°C), causing the battery temperature to drop; if the temperature is below the optimal operating temperature, it begins to solidify and release heat because it reaches the freezing point of sodium thiosulfate pentahydrate, causing the battery temperature to rise. When the battery temperature continues to rise above 100°C, sodium thiosulfate pentahydrate dehydrates and absorbs a large amount of heat, initially suppressing thermal runaway; when the battery temperature rises further, sodium thiosulfate reaches its chemical decomposition temperature of 310°C and decomposes and absorbs heat, suppressing the spread of thermal runaway.

[0117] Example 5

[0118] A full-temperature-range battery thermal management device based on a hydrated salt composite material is disclosed. The device comprises a cabinet, a composite material composed of sodium sulfate decahydrate, sodium acetate trihydrate, and expanded graphite, and a lithium-ion battery pack. The expanded graphite, sodium sulfate decahydrate, and sodium acetate trihydrate are prepared as a composite material in a ratio of 10:45:45. The performance parameters of the composite material are shown in Table 1 below. The battery thermal management device shown in Example 5 has the same structure as that in Example 1, except that the hydrated salt material is a combination of sodium sulfate decahydrate and sodium acetate trihydrate. The combination method involves mixing the two materials and wrapping them around the battery in two layers (top and bottom) or two layers (inner and outer), which is applied to scenarios requiring high-rate charging and discharging and precise temperature control.

[0119] The battery thermal management device is controlled to operate according to the above-described battery thermal management method: At this time, due to the use of two hydrated salt materials for synergistic temperature control, it has two phase change temperature control intervals and a desorption heat absorption interval, which can cover a wider temperature range and effectively control the battery temperature in a timely manner.

[0120] Comparative Examples 1, 2 and 3

[0121] Expanded graphite and paraffin were respectively prepared into composite materials according to the proportions shown in Table 1, and used in the full-temperature range battery thermal management device described in this application. The thermal management performance was tested, and the test results are shown in Table 1 below.

[0122] Table 1. Performance test results of composite materials obtained from each embodiment and comparative example.

[0123]

[0124] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A full-temperature-range battery thermal management method based on hydrated salt composite materials, characterized in that, A composite material is disposed on the outside of the battery for thermal management. The composite material includes a porous dielectric framework and hydrated salts filled in the porous dielectric framework. The optimal operating temperature range of the battery is T0~T1, where T0 is the lower limit temperature of the optimal operating temperature range and T1 is the upper limit temperature of the optimal operating temperature range. The full-temperature-range battery thermal management method includes the following steps: S1, Preheating before charging and discharging: Before the battery is charged or discharged, the ambient temperature T is preheated. 环 Perform the test, if T 环 If T < T0, then the battery is preheated; if T < T0, then the battery is preheated. 环 If T0 is greater than or equal to T0, then the battery is directly charged and discharged. The preheating of the battery includes: S103, obtaining a first preset threshold T. 阈1 Compared with the ambient temperature T 环 and the first preset threshold T 阈1 The relative size of T 环 <T 阈1 If T is low temperature, the battery will be preheated at ultra-low temperature; if T 阈1 ≤T 环 If so, the battery is preheated at a low temperature; The low-temperature preheating involves introducing air into the composite material, where the hydrated salts in the composite material adsorb water vapor from the air and release heat to preheat the battery in a low-temperature environment. S2, Temperature control during charging and discharging: During the charging and discharging process of the battery, when the battery temperature T... 电池 When the battery is within its optimal operating temperature range T0~T1, medium-temperature temperature control is applied; when the battery temperature T 电池 When the temperature is greater than T1, the battery is cooled by absorbing heat at high temperatures.

2. The full-temperature-range battery thermal management method based on hydrated salt composite materials according to claim 1, characterized in that, Step S1 also includes: S101, before the battery is charged or discharged, the ambient temperature T is monitored. 环 Conduct testing; S102, compared to ambient temperature T 环 The relative size of T0, if T 环 If T < T0, then continue with step S103. 环 If the value is ≥T0, then the battery will be directly charged and discharged.

3. The full-temperature-range battery thermal management method based on hydrated salt composite materials according to claim 2, characterized in that, Step S103 also includes: When T 阈1 ≤T 环 At that time, obtain the second preset threshold T. 阈2 , among which, T 阈1 <T 阈2 <T0; compared to ambient temperature T 环 Second preset threshold T 阈2 The relative size of T 阈1 ≤T 环 <T 阈2 Then the battery is preheated at a low temperature.

4. The full-temperature-range battery thermal management method based on hydrated salt composite materials according to claim 3, characterized in that, Step S103 also includes: If T 环 <T 阈1 If the battery is subjected to ultra-low temperature preheating, then the battery temperature T is controlled. 电池 Monitoring is conducted when the electrical T 阈2 ≤T 电池 At this point, stop the ultra-low temperature preheating of the battery and switch to low temperature preheating until the battery temperature T is reached. 电池 The lower limit temperature T0 of the optimal operating temperature range.

5. The full-temperature-range battery thermal management method based on hydrated salt composite materials according to any one of claims 2, 3, or 4, characterized in that, In step S103, the ultra-low temperature preheating method involves applying an electric current to the porous medium skeleton to convert electrical energy into heat energy through the Joule effect to preheat the battery in the ultra-low temperature environment.

6. The full-temperature-range battery thermal management method based on hydrated salt composite materials according to claim 1, characterized in that, Step S2 includes: S201, during the charging and discharging process of the battery, the battery temperature T is monitored. 电池 Monitoring is performed when the battery temperature T 电池 When the battery is within its optimal operating temperature range T0~T1, medium-temperature temperature control is applied; when the battery temperature T... 电池 When T1 is reached, step S202 is executed to cool the battery by absorbing heat at high temperature. S202, obtain the preset temperature value T2, where T1 < T2, and determine the battery temperature T. 电池 The relative magnitude of the preset temperature value T2, when T1 < T 电池 When T < T2, the battery is cooled by the heat absorption of hydrated salt dehydration and the heat absorption of water vapor escape; when T < T2, the battery is cooled by the heat absorption of hydrated salt dehydration and water vapor escape. 电池 When the temperature is greater than T2, the battery is cooled by endothermic heat absorption through high-temperature phase change of anhydrous salt or endothermic heat absorption through high-temperature thermochemical decomposition of anhydrous salt.

7. The full-temperature-range battery thermal management method based on hydrated salt composite materials according to claim 1 or 6, characterized in that, In step S2, the intermediate temperature control is achieved through a reversible phase transition of the hydrated salt.

8. A full-temperature-range battery thermal management device based on hydrated salt composite materials, characterized in that, The full-temperature-range battery thermal management device employs the full-temperature-range battery thermal management method according to any one of claims 1 to 7 to perform thermal management on the battery, and the battery thermal management device includes: A battery pack consisting of several batteries connected in series or in parallel; A composite material wrapped around the outside of a battery, the composite material comprising hydrated salts and a porous dielectric framework, wherein the hydrated salts fill the porous dielectric framework; The battery pack is housed in a cabinet, and the composite material is connected to a power supply device that can apply current to the composite material.

9. The full-temperature-range battery thermal management device based on hydrated salt composite material according to claim 8, characterized in that, The hydrated salt is one or more of sodium sulfate decahydrate, sodium acetate trihydrate, and sodium thiosulfate pentahydrate; the porous medium framework is expanded graphite or foamed metal.

10. The full-temperature-range battery thermal management device based on hydrated salt composite material according to claim 8, characterized in that, An air vent with an adjustable opening area is provided on the cabinet.

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