US-20260128422-A1 - HEAT ABSORBER AND SECONDARY BATTERY MODULE PROVIDED WITH HEAT ABSORBER

Abstract

A heat absorber having an excellent heat absorption property, heat insulation property, and pressure resistance and being capable of changing into a heat insulator in a high temperature range, and a secondary battery module including the heat absorber are provided. The heat absorber includes a bag fillable with a content, and an aqueous solvent and a water-soluble inorganic powder configured to fill the bag as the content. The secondary battery module includes the heat absorber.

Inventors

• Kenichi Fujisaki
• Kyouichi TOYOMURA

Assignees

• DIC CORPORATION

Dates

Publication Date

20260507

Application Date

20251219

Priority Date

20230703

Claims (9)

1. 1 . A heat absorber comprising: a bag fillable with a content; and an aqueous solvent and a water-soluble inorganic powder that dissolves in an amount of 1 g or more in 100 g of water at 20° C., wherein the bag is filled with the aqueous solvent and the water-soluble inorganic powder as the content.
2. 2 . The heat absorber according to claim 1 , wherein the water-soluble inorganic powder has a solubility (g) of 5 g/100 g or more in water at 20° C.
3. 3 . The heat absorber according to claim 1 , wherein the content further contains one or more selected from the group consisting of an antifreezing agent and an inorganic fiber.
4. 4 . The heat absorber according to claim 1 , wherein the water-soluble inorganic powder is one or more selected from a chloride, a sulfate, a carbonate, a nitrate, a phosphate, an acetate, an alkali metal oxide, and an alkaline earth metal oxide.
5. 5 . The heat absorber according to claim 1 , wherein the bag contains, as the content, an aqueous solution containing the aqueous solvent and the water-soluble inorganic powder, and an amount of the water-soluble inorganic powder in the aqueous solution is 5 mass % to 80 mass % with respect to a total amount of the aqueous solution.
6. 6 . The heat absorber according to claim 1 , wherein the content changes into a porous body when the content is heated to 120° C. or higher.
7. 7 . The heat absorber according to claim 1 , wherein a rate of change in thickness of the heat absorber is 70% or more, and the rate of change in thickness is represented by equation (I), the equation (I): rate of change in thickness (%)=(thickness of the heat absorber after pressing, at 0.5 MPa for 60 seconds, surface of the heat absorber heated under following heating conditions)/(thickness of the heat absorber before pressing, at 0.5 MPa for 60 seconds, surface of the heat absorber heated under following heating conditions)×100, wherein in the heating conditions, after heating the heat absorber with a heat amount of 50 kW/m 2 by radiant heat until a temperature of a surface opposite to a heated surface (back surface) reaches a predetermined temperature, allowing the heat absorber to dissipate heat at room temperature, and naturally cooling until a temperature of the surface of the heat absorber reaches the room temperature, and wherein the heated surface of the heat absorber is pressed at 0.5 MPa for 60 seconds.
8. 8 . A secondary battery module comprising the heat absorber according to claim 1 .
9. 9 . The secondary battery module according to claim 8 , wherein the heat absorber is sandwiched between battery cells.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims the profits of priority for the three applications of Japanese Patent Application (No. 2023-109644) filed on Jul. 3, 2023, Japanese Patent Application (No. 2023-218613) filed on Dec. 25, 2023, and Japanese Patent Application (No. 2023-218614) filed on Dec. 25, 2023, contents of which are incorporated in the present description as reference. TECHNICAL FIELD The present disclosure relates to a heat absorber and a secondary battery module including the heat absorber. BACKGROUND Secondary batteries capable of controlling a time difference between power storage and demand are used in various applications such as an automobile and a mobile device, and are required for expansion of introduction of renewable energy from the viewpoint of low carbon society construction or energy security, and thus the importance thereof is further increasing at present. However, in a secondary battery represented by a lithium ion battery, when the temperature of the battery rises due to heat generation during high-speed charging or high-output discharging, there is a risk of breakage of the battery due to thermal runaway. Further, in the future, it is predicted that the heat generation amount further increases as the ultra-high speed charging proceeds, and the development of a temperature rise suppression method for improving the safety of the battery is required. In addition, the secondary battery may experience thermal runaway due to an internal short circuit or the like, and may have ignition or smoke generation. Therefore, in order to minimize the damage due to the above, there is a demand for a technique of suppressing, preventing, or delaying chain explosion by extinguishing the heat of the battery having an abnormally high temperature by heat absorption or by suppressing heat transfer to other battery cells (hereinafter, may be referred to as battery cells or simply cells) by heat absorption and heat insulation. For example, PTLs 1 and 2 are cited as techniques excellent in heat insulation property and fire spread preventing property. PTL 1 describes a fire spread preventing material for a laminate including a layer A containing sodium silicate having a SiO2/Na2O molar ratio of less than 3.1 and a layer B containing precipitated silica. Then, according to PTL 1, since the fire spread preventing material is used in a battery pack including two or more cells, heat transfer between the cells is suppressed in a normal state, and heat spread to adjacent cells is suppressed in an abnormal state. In addition, PTL 2 describes a partition member including a liquid, a heat insulating material, and an exterior body that accommodates the liquid and the heat insulating material. Further, PTL 2 discloses that by appropriately setting the peel strength of a sealant resin layer of a sheet-shaped member in contact with the heat insulating material and the crystal melting properties of the sealant resin layer, the partition member maintains a cooling function during long-term use and has excellent stability at a release temperature of the cooling liquid inside the sheet-shaped member. PATENT LITERATURE PTL 1: WO2022/270359PTL 2: JP2020-161290A However, in the technique of PTL 1, since water (for example, water molecules in sodium silicate) contained in the layer A is generated by causing a heat absorption reaction in a temperature range of 100° C. to 300° C., the content of water is limited, and a sufficient heat absorption effect cannot be obtained. In addition, the technique of PTL 2 only lists various porous bodies, fibers, or particles as the heat insulating material, and does not consider at all the point that in a battery having an abnormally high temperature, the partition member itself exhibits a heat insulation effect to suppress the heat transfer to other cells, thereby suppressing, preventing, or delaying the chain explosion. Further, in the case where a separator member such as the partition member in PTL 2 is used in a laminated secondary battery, when the expansion and contraction of the cell itself due to charging and discharging or the rapid expansion of the cell during the thermal runaway occurs, the thickness between the adjacent cells changes, and thus the separator member is required to have mechanical properties such as a predetermined pressure resistance. However, since the mechanical properties such as a pressure resistance are not considered in PTL 2, heat is easily transferred between the adjacent cells since a distance between the cells is shortened particularly when the cells expand. Therefore, a heat absorber having an excellent heat absorption property and being capable of changing into a heat insulator in a high temperature range to have an excellent heat insulation property and pressure resistance, and a secondary battery module including the heat absorber are provided. SUMMARY The present inventors have found that a heat absorber containing a