Composite heat preservation material and heat preservation protection method for lithium sub-battery

Abstract

The present application relates to a kind of composite thermal insulation materials and thermal protection method for lithium sub-battery, belong to battery thermal protection technology.The present application provides a kind of thermal insulation scheme of disposable lithium sub-battery, through the five-layer thermal insulation structure of shell-flexible aerogel felt-aluminum foil paper-air-EVA foam-aerogel powder-battery, the constant temperature of lithium battery is maintained when discharging, especially for lithium battery in the case of using in the summer high temperature exposure or winter extremely cold environment, can effectively improve the discharge voltage of battery, increase the discharge capacity of battery, maintain the temperature of battery, and the electrical equipment can work normally.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of battery heat preservation protection, and particularly relates to a composite heat preservation material for a lithium sub-battery and a heat preservation protection method for a lithium sub-battery. BACKGROUND

[0002] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the general background of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art that is publicly known as of the priority date of the present application.

[0003] The current heat preservation protection method for a lithium sub-battery mainly involves wrapping the battery with a thermal insulation material or filling it with a polyurethane foaming agent, and the heat preservation effect is poor. Poor heat preservation protection can cause the voltage of the battery to drop sharply in a low-temperature state, the discharge capacity to decrease greatly, the leakage current of the battery to increase rapidly in a high-temperature state, and the heat of the battery to increase, thereby increasing the risk of explosion of the battery.

[0004] The commonly used battery heat preservation materials include foam, plastic foam, ultra-fine glass wool, high-silica wool, vacuum thermal insulation board, and silica aerogel. The aerogel has the advantages of low thermal conductivity, good heat preservation effect, and non-flammability. Compared with traditional heat preservation materials, the aerogel only needs 1 / 5-1 / 3 of the thickness to achieve the same heat preservation effect, and has important application prospects in the new energy field. However, in order to achieve the ideal heat preservation effect of the battery, the thickness of the heat preservation material needs to be increased, which will inevitably increase the thickness and processing difficulty of the battery pack.

[0005] In view of the above research status, the inventors believe that in order to provide an ideal battery heat preservation effect, it is urgent to study a heat preservation protection method with a multi-layer composite structure to improve the heat preservation effect while reducing the thickness of the heat preservation layer. SUMMARY

[0006] Based on the above technical background, the present application provides a combination of aerogel felt, air, aluminum foil, closed-cell foam material, and aerogel particles to achieve a protection method that insulates conductive heat and radiant heat. This method can effectively prolong the discharge time of the battery in extreme environments, maintain the stability of the lithium sub-battery in normal working environments, and improve the safety performance of the battery.

[0007] Based on the above technical effects, the present application provides the following technical solutions:

[0008] In a first aspect, the present application provides a composite heat preservation material for a lithium sub-battery, which comprises the following materials:

[0009] The flexible aerogel felt has a density of 130±20 kg / m 3 and a thermal conductivity of 0.014-0.023 W / (m·K).

[0010] Aluminum foil, preferably glass cloth aluminum foil;

[0011] EVA closed-cell foam insulation support structure, thermal conductivity is 0.030-0.035 W / (m·K);

[0012] Aerogel powder, size is 18-22 nm.

[0013] In the above scheme, the flexible aerogel felt serves as the first layer of thermal protection. Based on the high flexibility, the flexible aerogel felt can be completely attached to the inside of the battery pack shell, ensuring that the thermal insulation layer will not have gaps or leaks. And the flexible aerogel felt has low thermal conductivity, which can effectively prevent the invasion of external cold or hot air into the device.

[0014] The aluminum foil is the second layer of thermal protection, which can be attached to the flexible aerogel felt by adhesive means. Considering the convenience of construction, the aluminum foil can be selected as a single-sided adhesive product to facilitate the fixation of the aluminum foil. The aluminum foil is about 0.1 mm thick and very thin, which can effectively reduce the space occupied by the thermal insulation material; preferably, a double-sided silver aluminum foil is used, which can effectively prevent the radiation transfer of heat.

[0015] The EVA closed-cell foam insulation support structure is cold-pressed into a hollow barrel shape with enough space to accommodate the lithium sub-battery. This support structure has certain mechanical strength and pressure resistance, which is used to fix the lithium sub-battery and has a protective effect on the battery.

[0016] The aerogel powder is used to fill the gap between the lithium sub-battery and the EVA closed-cell foam insulation support structure. The aerogel powder has the advantage of low density, which can well fix the position of the lithium sub-battery and reduce the vibration and displacement of the battery caused by external factors. At the same time, the aerogel powder has a large specific surface area, which is beneficial to the good thermal insulation effect.

[0017] In a second aspect, a battery pack of a lithium sub-battery is provided, which includes the composite thermal insulation material of the first aspect.

[0018] In the battery pack, the above-mentioned composite thermal insulation material is sequentially filled between the lithium sub-battery and the shell, wherein there is a gap between the aluminum foil and the EVA closed-cell foam insulation support structure, forming an air layer. The setting of the air layer takes advantage of the air insulation characteristics to reduce the heat transfer between the battery and the outside world, ultimately forming a five-layer thermal insulation structure of shell-flexible aerogel felt-aluminum foil-air layer-EVA closed-cell foam insulation support structure-aerogel powder-lithium sub-battery.

[0019] In a third aspect, a thermal protection method for a lithium sub-battery is provided, which is based on the composite thermal insulation material of the first aspect and includes the following steps:

[0020] The flexible aerogel felt is pasted to the inner side of the shell, the other side is covered with aluminum foil; the lithium sub-battery is placed in the EVA closed-cell foam support structure, and the gap is filled with aerogel powder; the EVA closed-cell foam support structure wrapping the battery is placed in the shell, and a gap is reserved between the EVA foam support structure and the aluminum foil to form an air layer.

[0021] The beneficial effects of one or more of the above technical solutions are:

[0022] 1) The heat preservation scheme effectively prevents the radiative heat transfer, heat conduction and convective heat exchange between the battery and the outside. The battery is effectively insulated by using the aerogel layer, the aluminum foil layer, the air layer and the foam cotton support layer. The overall insulation layer is thin and has good insulation effect, which is very suitable for the insulation design of lithium batteries for outdoor instruments and meters. It prevents the battery from being too low in voltage and discharging too little in winter due to low temperature. At the same time, it also effectively prevents the battery from exploding due to high temperature during discharging in summer.

[0023] 2) The heat preservation method is easy to realize mass production application and is applied to multiple products, saving a lot of production cost. It overcomes the shortcomings of small discharge in winter and easy explosion in summer of lithium sub-batteries.

[0024] 3) The heat preservation method is simple, efficient, easy to popularize and has strong practicality. BRIEF DESCRIPTION OF DRAWINGS

[0025] The drawings accompanying the specification of this application form a part of the application and serve to further illustrate the application, its preferred embodiments and the description thereof. The drawings are not intended to limit the application in any way.

[0026] Figure 1 A schematic diagram of the lithium sub-battery heat preservation protection structure described in Example 1;

[0027] In the figure, 1 is a shell, 2 is a flexible aerogel felt, 3 is an aluminum foil, 4 is an air layer, 5 is an EVA closed-cell foam support structure, 6 is an aerogel powder, and 7 is a lithium sub-battery. DETAILED DESCRIPTION

[0028] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs.

[0029] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0030] As introduced in the background, the existing battery insulation technology has a single way, such as increasing the thickness of the insulation material to improve the insulation effect. The disadvantage of this way is that the increase in thickness will cause the increase in hardness of the insulation material, and the insulation layer is not easy to bend and is difficult to fix and form, resulting in a sealed gap. Or simply use a foaming agent to fill, which cannot form closed and sealed bubbles, and cannot take into account multiple heat transfer modes such as radiant heat, convective heat and thermal conductivity. Therefore, the present application proposes a composite insulation material solution applied to the insulation protection of lithium sub-battery.

[0031] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in conjunction with specific embodiments.

[0032] Embodiment 1

[0033] A composite insulation material and an insulation protection method for a lithium sub-battery (19AH) are provided in this embodiment.

[0034] The composite insulation material is composed of the following materials: a flexible aerogel felt (SACF-1-2 aerogel felt of the brand of Aerospace Science and Technology), a glass cloth aluminum foil with a thickness of 0.1 mm, an EVA closed-cell foaming support structure with a thickness of 3 mm, and aerogel powder. The glass cloth aluminum foil is covered with glue on one side and can be pasted on the surface of the flexible aerogel felt; the EVA closed-cell foaming support structure is cold-pressed and has a barrel shape with enough space to accommodate the lithium sub-battery; the pore size of the aerogel powder is 20 nm.

[0035] The insulation protection method based on the above composite insulation material is as follows: as shown in Figure 1 The lithium sub-battery 7 (19AH) is placed in the EVA closed-cell foaming support structure 5, and the gap is filled with aerogel powder 6. The flexible aerogel felt 2 is pasted on the inner side of the lithium sub-battery shell 1, and the other side is pasted with the glass cloth aluminum foil 3. The EVA closed-cell foaming support structure wrapping the battery is placed in the shell, and a gap is reserved between the EVA foaming support structure 5 and the aluminum foil 3 to form an air layer 4.

[0036] The above heat preservation structure is detected in a low temperature environment, a lithium sub battery (19AH) is wrapped with the above composite heat preservation material, and the same thickness of a conventional rubber foaming heat preservation material is wrapped for comparison, the battery is placed from normal temperature 25 DEG C to-30 DEG C environment for testing, and the discharge duration of the battery is observed, and the results are shown in Table 1:

[0037] Table 1 low temperature environment 2.5Ω load discharge duration

[0038]

[0039] The above heat preservation layer is detected in a high temperature environment, a lithium sub battery (19AH) is wrapped with the above composite heat preservation material, and the same thickness of a conventional rubber foaming heat preservation material is wrapped for comparison, the battery is placed from normal temperature 25 DEG C to 100 DEG C environment, and the temperature of the battery shell is detected, and the test results are shown in Table 2:

[0040] Table 2 high temperature environment battery surface temperature

[0041]

[0042] Example 2

[0043] In this embodiment, another composite heat preservation material for lithium sub battery (19AH) is provided, which is different from example 1 in that the flexible aerogel felt in example 1 is replaced by glass fiber felt. The discharge duration is recorded under the same conditions as example 1

[0044] Table 3 low temperature environment 2.5Ω load discharge duration

[0045]

[0046] Example 3

[0047] In this embodiment, another composite heat preservation material for lithium sub battery (19AH) is provided, which is different from example 1 in that it does not have an air layer. The discharge duration is recorded under the same conditions as example 1

[0048] Table 4 low temperature environment 2.5Ω load discharge duration

[0049]

[0050] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A composite thermal insulation material for lithium sub-batteries, characterized in that, The flexible aerogel felt, the aluminum foil, the air layer, the EVA closed-cell foaming heat preservation support structure and the aerogel powder are sequentially arranged. The flexible aerogel felt; The aluminum foil; The EVA closed-cell foaming heat preservation support structure has a thermal conductivity of 0.030-0.035 W / (m·K). The aerogel powder has a pore size of 18-22 nm. The aerogel powder is used to fill the gap between the lithium sub-battery and the EVA closed-cell foaming heat preservation support structure.

2. The composite thermal insulation material for lithium sub-batteries according to claim 1, wherein The aluminum foil is a glass cloth aluminum foil.

3. The composite thermal insulation material for lithium sub-batteries according to claim 1, wherein The aluminum foil is a double-sided aluminum foil or a single-sided adhesive-coated aluminum foil.

4. The composite thermal insulation material for lithium sub-batteries according to claim 1, wherein The EVA closed-cell foaming heat preservation support structure is cold-pressed into a hollow barrel shape and has a space sufficient to accommodate the lithium sub-battery.

5. A battery pack of lithium sub-batteries, characterized in that, The battery pack comprises the composite heat preservation material according to any one of claims 1-4.

6. The battery pack of lithium sub-batteries according to claim 5, characterized in that, In the battery pack, the composite heat preservation material is sequentially filled between the lithium sub-battery and the shell, wherein the aluminum foil and the EVA closed-cell foaming heat preservation support structure have a gap therebetween to form an air layer.

7. A method for protecting a lithium sub-battery from heat, characterized by, The protection method is based on the composite heat preservation material according to any one of claims 1-4.

8. The method of claim 7, wherein the lithium sub-battery is a lithium ion battery. The method comprises the following steps: The flexible aerogel felt is pasted to the inner side of the shell, and the other side is covered with the aluminum foil; the lithium sub-battery is placed in the EVA closed-cell foaming support structure, and the gap is filled with the aerogel powder; the EVA closed-cell foaming support structure wrapped around the battery is placed in the shell, and a gap is reserved between the EVA foaming support structure and the aluminum foil to form an air layer.

Images