A temperature-resistant energy storage device and its preparation method

Abstract

The present application belongs to the technical field of phase change materials, and in particular relates to a temperature-resistant variable energy storage device and a preparation method thereof. The temperature-resistant variable energy storage device provided in the present application includes a temperature control layer and an energy storage device coated thereon. The temperature control layer includes a composite phase change material and low thermal conductivity particles. The mass concentration gradient distribution of the low thermal conductivity particles increases toward the back of the energy storage device. This structure can accelerate the cooling rate during cooling and shorten the time the energy storage device is in a high-temperature state, thereby solving the technical problem in the prior art that energy storage devices coated with both thermal insulation materials and phase change materials have a slow temperature reduction rate during cooling, resulting in the energy storage device being in a high-temperature state for an excessively long time.

Description

Technical Field

[0001] The present application belongs to the technical field of phase change materials, and in particular relates to a temperature-resistant energy storage device and a preparation method thereof. Background Art

[0002] Energy storage devices such as lithium-ion batteries, supercapacitors, and lead-acid batteries tend to generate heat during the charging and discharging process, especially during high-power charging and discharging. Heat accumulation in energy storage devices can easily lead to safety accidents and shorten their service life. When energy storage devices are used in high-temperature environments, heat accumulation in the energy storage devices will be further exacerbated, leading to failure of the energy storage devices. At the same time, the use of energy storage devices in low-temperature environments will also affect their service life and may cause internal short circuits. Therefore, it is necessary to improve the temperature variation resistance of energy storage devices.

[0003] Phase change materials can absorb heat and cool down when the external temperature is higher than the phase change temperature, and release heat again to increase the temperature after the temperature is lower than the phase change temperature, maintaining temperature stability and exerting a temperature control effect. Therefore, using phase change materials to wrap energy storage devices can improve the temperature change resistance of energy storage devices. Application No. 201810871064.7 discloses a technical solution for controlling the temperature of energy storage devices using a phase change material layer and a thermal insulation layer. The provision of the thermal insulation layer improves the temperature change resistance of the energy storage device and reduces the possibility of failure of the energy storage device. However, the provision of the thermal insulation layer isolates the phase change material from the external heat exchange. The temperature of the energy storage device wrapped with the phase change material decreases too slowly when cooling, causing the energy storage device to remain in a high temperature state for too long, affecting the service life of the energy storage device. Summary of the Invention

[0004] In view of this, the present application provides a temperature-resistant variable energy storage device and a preparation method thereof, which are used to solve the technical problem in the prior art that the energy storage device wrapped with both insulation material and phase change material has a slow temperature reduction rate when cooled, resulting in the energy storage device being in a high temperature state for too long.

[0005] In a first aspect, the present application provides a temperature-resistant variable energy storage device, comprising an energy storage device and a temperature control layer;

[0006] The temperature control layer covers the energy storage device;

[0007] The temperature control layer includes a composite phase change material and low thermal conductivity particles;

[0008] The mass concentration gradient distribution of the low thermal conductivity particles in the temperature control layer increases in the direction away from the energy storage device.

[0009] Preferably, the low thermal conductivity particles are hollow particles.

[0010] Preferably, the hollow particles are hollow alumina particles.

[0011] Preferably, the diameter of the hollow alumina particles is 0.5 μm to 500 μm.

[0012] Preferably, the mass fraction of the hollow alumina particles in the temperature control layer is 10% to 50%.

[0013] Preferably, the thickness of the temperature control layer is 1 mm to 10 mm.

[0014] Preferably, the energy storage element is selected from any one of metal lithium batteries, lithium ion batteries, sodium ion batteries, lead-acid batteries, supercapacitors, nickel-hydrogen batteries, nickel-cadmium batteries, zinc ion batteries, and magnesium ion batteries.

[0015] Preferably, the composite phase change material comprises paraffin and polymer materials.

[0016] Preferably, the polymer material is selected from any one or at least two of polyethylene, polypropylene, polybutylene and polystyrene.

[0017] Preferably, the temperature-resistant variable energy storage device further includes a heat-conducting material layer, and the heat-conducting material layer covers the energy storage device.

[0018] Preferably, the thermally conductive material is selected from any one or at least two of graphene, expanded graphite, thermally conductive silicone grease, thermally conductive silica gel, thermally conductive insulating rubber, carbon fiber and thermally conductive ceramic powder.

[0019] Preferably, the phase change temperature of the composite phase change material is 35°C to 70°C.

[0020] Preferably, the phase change temperature of the composite phase change material is 35°C to 55°C.

[0021] Preferably, the phase change temperature of the composite phase change material is 40°C to 50°C.

[0022] A second aspect of the present application provides a method for preparing a temperature-resistant variable energy storage device, the preparation method comprising the steps of:

[0023] Step S1: first pouring a composite phase change material without low thermal conductivity particles into a mold, then sequentially pouring a heated mixture containing low thermal conductivity particles with gradually increasing mass concentrations into the mold, and curing and forming the mixture in the mold to obtain a temperature control layer;

[0024] Step S2: Covering the surface of the energy storage device with a temperature control layer to obtain a temperature-resistant energy storage device.

[0025] In summary, the present application provides a temperature-resistant variable energy storage device and a preparation method thereof, wherein the temperature-resistant variable energy storage device comprises a temperature control layer and an energy storage device coated thereon, wherein the temperature control layer comprises a composite phase change material and low thermal conductivity particles, and the mass concentration gradient distribution of the low thermal conductivity particles is increasing toward the back of the energy storage device, that is, there are no low thermal conductivity particles in the composite phase change material close to the side of the energy storage device, and the side away from the energy storage device has the highest mass concentration of low thermal conductivity particles, the composite phase change material bonded to the energy storage device can quickly transfer the heat released by the energy storage device to the phase change material, and the low thermal conductivity particles away from the side of the energy storage device can be The heat exchange between the energy storage device and the external environment is blocked, and the adverse effects of the external high temperature environment on the energy storage device are mitigated. Moreover, compared with covering the surface of the phase change material with a thermal insulation layer, in the present application, the concentration gradient distribution of the low thermal conductivity particles in the phase change material increases towards the back of the energy storage device, so that the heat released by the energy storage device can be transferred outward, and the cooling speed can be accelerated during cooling, shortening the time that the energy storage device is in a high temperature state. This solves the technical problem in the prior art that the energy storage device wrapped with both thermal insulation material and phase change material has a too slow temperature reduction rate during cooling, resulting in the energy storage device being in a high temperature state for too long. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 A schematic structural diagram of a temperature-resistant variable energy storage device provided in Example 1 of the present application;

[0028] Figure 1 In the figure, the reference numerals are 1-low thermal conductivity particles, 2-composite phase change material, and 3-energy storage device. DETAILED DESCRIPTION

[0029] The present application provides a temperature-resistant variable energy storage device and a preparation method thereof, which are used to solve the technical problem in the prior art that the energy storage device wrapped with both thermal insulation material and phase change material has a slow temperature reduction rate during cooling, resulting in the energy storage device being in a high temperature state for too long.

[0030] The following will clearly and completely describe the technical solution of this application in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0031] Example 1

[0032] In view of the fact that covering the surface of the phase change material with an insulating layer easily causes the phase change material to be isolated from the heat exchange with the outside world, the energy storage device wrapped by the phase change material will reduce the temperature too slowly when cooling, thereby causing the energy storage device to be in a high temperature state for too long, thus affecting the service life of the energy storage device, this embodiment 1 provides a temperature-resistant energy storage device, whose structure is as follows: Figure 1 As shown, it includes an energy storage device 3 and a temperature control layer; the temperature control layer covers the energy storage device; the temperature control layer includes a composite phase change material 2 and low thermal conductivity particles 1, and the low thermal conductivity particles are selected from hollow particles; wherein, the concentration gradient distribution of the low thermal conductivity particles causes the thermal conductivity of the temperature control layer to gradually decrease from the inside (the side close to the energy storage device) to the outside (the side away from the energy storage device). The side close to the energy storage device can maintain the ability of the temperature control layer to quickly absorb the heat of the energy storage device, thereby reducing the temperature of the energy storage device. The side away from the energy storage device blocks the heat exchange rate between the external environment and the composite phase change material, thereby reducing the adverse effects of the external high temperature environment on the energy storage device. Moreover, when cooling, since the heat released by the energy storage device can be transferred outward, the cooling rate can be accelerated, the time the energy storage device is in a high temperature state can be shortened, and the risk of easy failure of the energy storage device can be reduced.

[0033] Preferably, the low thermal conductivity particles are hollow alumina particles with a particle size of 0.5 μm to 500 μm, and the mass fraction of the hollow alumina particles in the temperature control layer is 10% to 50%.

[0034] Preferably, the thickness of the temperature control layer is 1 mm to 10 mm, and the composite phase change material in the temperature control layer includes paraffin and polymer materials, wherein the polymer material improves the toughness of the composite phase change material and provides structural support for the composite phase change material. A thermal conductive material layer is distributed inside the temperature-resistant energy storage device, and the thermal conductive material layer can improve the thermal conductivity between the composite phase change material and the energy storage device; the polymer material is selected from any one or at least two of polyethylene, polypropylene, polybutylene, and polystyrene, and the thermal conductive material constituting the thermal conductive material layer is selected from any one or at least two of graphene, expanded graphite, thermal conductive silicone grease, thermal conductive silica gel, thermal conductive insulating rubber, carbon fiber, and thermal conductive ceramic powder; the phase change temperature of the composite phase change material is 35°C to 70°C.

[0035] Example 2

[0036] Example 2 of the present application provides a method for preparing the temperature-resistant variable energy storage device described in Example 1, and the preparation method includes preparing a temperature control layer and preparing a temperature-resistant variable energy storage device.

[0037] The step of preparing the temperature control layer includes mixing hollow alumina particles, paraffin wax, and polyethylene in different proportions, heating the mixture, and then pouring the mixture into a mold. The mixture without hollow alumina particles is poured into the mold first, and then the mixture containing hollow alumina particles with gradually increasing mass concentrations is poured into the mold. After cooling, the mass concentration of the hollow alumina particles gradually increases from the inside (the side close to the energy storage device) to the outside (the side away from the energy storage device), thereby obtaining a temperature control layer with a thermal conductivity gradually decreasing from the inside (the side close to the energy storage device) to the outside (the side away from the energy storage device). The thickness of the temperature control layer is 10 mm, and the mass fraction of the hollow alumina particles in the temperature control layer is 40%.

[0038] The preparation of a temperature-resistant variable energy storage device includes coating a temperature-control layer on the surface of a 20Ah lithium iron phosphate battery of the energy storage device. During the preparation process, the temperature-control layer is prefabricated into a rigid shell suitable for the shape of the energy storage device, and then the energy storage device is filled into the temperature-control layer shell. The temperature-control layer can also be prefabricated into a rigid or flexible block structure and bonded to the energy storage device via an adhesive to form the energy storage device containing the temperature-control layer provided by the present invention.

[0039] Example 3

[0040] Example 3 of the present application provides another method for preparing the temperature-resistant variable energy storage device described in Example 1, and the preparation method includes preparing a temperature control layer and preparing a temperature-resistant variable energy storage device.

[0041] The step of preparing the temperature control layer includes mixing hollow alumina particles, paraffin wax, and polyethylene in different proportions, heating the mixture, and then pouring the mixture into a mold. The mixture without hollow alumina particles is poured into the mold first, and then the mixture containing hollow alumina particles with gradually increasing mass concentrations is poured into the mold. After cooling, the mass concentration of the hollow alumina particles gradually increases from the inside (the side close to the energy storage device) to the outside (the side away from the energy storage device), thereby obtaining a temperature control layer with a thermal conductivity gradually decreasing from the inside (the side close to the energy storage device) to the outside (the side away from the energy storage device). The thickness of the temperature control layer is 10 mm, and the mass fraction of the hollow alumina particles in the temperature control layer is 40%.

[0042] The preparation of a temperature-resistant variable energy storage device includes coating a temperature-control layer on the surface of a 20Ah lithium iron phosphate battery of the energy storage device. During the preparation process, the temperature-control layer is prefabricated into a rigid shell suitable for the shape of the energy storage device, and then a layer of graphene thermal conductive material is covered on the inner layer of the temperature-control layer. Finally, the energy storage device is filled into the temperature-control layer shell. The temperature-control layer can also be prefabricated into a rigid or flexible block structure, and bonded to the energy storage device with an adhesive to form the energy storage device containing the temperature-control layer provided by the present invention. That is, the temperature-resistant variable energy storage device is arranged from the inside out as an energy storage device, a graphene thermal conductive material layer, and a temperature-control layer.

[0043] Comparative Example 1

[0044] Comparative Example 1 provides a temperature-resistant variable energy storage device. The difference between the preparation method and Example 2 is that the temperature control layer on the surface of the temperature-resistant variable energy storage device is a double-layer structure, the composite phase change material layer covers the energy storage device, and the hollow alumina aerogel layer covers the composite phase change material layer.

[0045] Experimental Example 1

[0046] This experimental example is used to test the performance of the temperature-resistant variable energy storage devices provided in Examples 1-2 and Comparative Example 1. The performance test process includes placing the temperature-resistant variable energy storage devices in a 50°C environment for 2 hours and then in a 25°C environment for 2 hours. The test results are shown in Table 1.

[0047] Table 1

[0048]

[0049] As can be seen from Table 1, the temperature-resistant variable energy storage device provided in Comparative Example 1 has a slow heating rate and a low maximum temperature in a 50°C environment due to the presence of the hollow alumina aerogel insulation layer. However, when the temperature-resistant variable energy storage device is transferred to a 25°C environment, the heat released by the energy storage device and the phase change material cannot be quickly transferred outward due to the presence of the insulation layer, and the cooling rate is slow, resulting in the temperature-resistant variable energy storage device being at a high temperature for a long time. When the temperature-resistant variable energy storage device provided in Example 1 is cooled, the heat released by the energy storage device and the phase change material is not quickly transferred outward. The released heat can be transferred outward, and compared with providing a heat insulation layer, the cooling speed can be accelerated during cooling, the time the energy storage device is in a high-temperature state is shortened, and the risk of the energy storage device being prone to failure is reduced; therefore, the temperature-resistant variable energy storage device provided in Comparative Example 1 can reduce the heating speed in a high-temperature environment, while the temperature-resistant variable energy storage device provided in Example 1 of the present application can not only reduce the heating speed in a high-temperature environment, but more importantly, in a low-temperature environment, it can effectively exchange heat with the outside world, accelerate the cooling speed, shorten the time the energy storage device is in a high-temperature state, and reduce the risk of failure of the energy storage device.

[0050] As can be seen from Table 1, compared with the temperature-resistant variable energy storage device provided in Example 2, the temperature-resistant variable energy storage device provided in Example 3 can further accelerate the cooling speed in a low-temperature environment and shorten the time the energy storage device is in a high-temperature state because a heat-conducting material layer is added to the temperature control layer.

[0051] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, 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 embodiments of the present application.

Claims

1. A temperature-resistant energy storage device, characterized in that: Including energy storage devices and temperature control layer; The temperature control layer covers the energy storage device; The temperature control layer includes a composite phase change material and low thermal conductivity particles; The mass concentration gradient distribution of the low thermal conductivity particles in the composite phase change material of the temperature control layer increases in the direction away from the energy storage device.

2. A temperature-resistant variable energy storage device according to claim 1, characterized in that: The temperature-resistant variable energy storage device further comprises a graphene thermal conductive material layer, and the graphene thermal conductive material layer covers the energy storage device; The temperature-resistant variable energy storage device is arranged from the inside outwards as an energy storage device, a graphene thermal conductive material layer, and a temperature control layer.

3. The temperature-resistant variable energy storage device according to claim 1, characterized in that: The low thermal conductivity particles are hollow particles, and the hollow particles include any one or more of hollow alumina particles, hollow silica particles, and hollow plastic particles.

4. The temperature-resistant variable energy storage device according to claim 3, characterized in that: The diameter of the hollow particles is 0.5 μm to 500 μm.

5. The temperature-resistant variable energy storage device according to claim 3, characterized in that: The mass fraction of the hollow particles in the temperature control layer is 10% to 50%.

6. The temperature-resistant variable energy storage device according to claim 1, characterized in that: The thickness of the temperature control layer is 1 mm to 10 mm.

7. The temperature-resistant variable energy storage device according to claim 1, characterized in that: The composite phase change material comprises paraffin and polymer materials.

8. The temperature-resistant variable energy storage device according to claim 7, characterized in that: The polymer material is selected from any one or at least two of polyethylene, polypropylene, polybutylene and polystyrene.

9. A method for preparing a temperature-resistant variable energy storage device, characterized in that: A temperature-resistant variable energy storage device according to any one of claims 1 and 3 to 8 can be prepared, comprising the steps of: Step S1: first pouring a composite phase change material without low thermal conductivity particles into a mold, then sequentially pouring a heated mixture of composite phase change materials containing gradually increasing concentrations of low thermal conductivity particles into the mold, and curing and forming the mixture in the mold to obtain a temperature control layer; Step S2: Covering the surface of the energy storage device with a temperature control layer to obtain a temperature-resistant energy storage device.

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