EP-4741699-A1 - HEAT ABSORBER AND SECONDARY BATTERY MODULE PROVIDED WITH HEAT ABSORBER

Abstract

An object of the present disclosure is to provide 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. The present disclosure provides a heat absorber including a bag fillable with a content, and an aqueous solvent and a water-soluble inorganic powder configured to fill the bag as the content, and a secondary battery module including the heat absorber.

Inventors

• FUJISAKI KENICHI
• TOYOMURA Kyouichi

Assignees

• DIC Corporation

Dates

Publication Date

20260513

Application Date

20240703

Claims (9)

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, which are configured to fill the bag as the content.
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. The heat absorber according to claim 1 or 2, wherein the content further contains one or two or more selected from the group consisting of an antifreezing agent and an inorganic fiber.
4. The heat absorber according to claim 1 or 2, wherein the water-soluble inorganic powder is one or two 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. The heat absorber according to claim 1 or 2, wherein an aqueous solution containing the aqueous solvent and the water-soluble inorganic powder fills the bag as the content, and a content 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. The heat absorber according to claim 1 or 2, wherein the content changes into a porous body when the content is heated to 120°C or higher.
7. The heat absorber according to claim 1 or 2, wherein a rate of change in thickness is 70% or more, which is represented by the following equation (I): "Rate of change in thickness (%) = (thickness of heat absorber after pressing, at 0.5 MPa for 60 seconds, surface of heat absorber heated under following heating conditions)/(thickness of heat absorber before pressing, at 0.5 MPa for 60 seconds, surface of heat absorber heated under following heating conditions) × 100" Heating conditions: "the heat absorber is heated with a heat amount of 50 kW/m 2 by radiant heat until a temperature of a surface opposite to the heated surface (back surface) reaches a predetermined temperature, then the heat absorber is allowed to dissipate heat at room temperature, and is naturally cooled until the temperature of the surface of the heat absorber reaches room temperature, and the rate of change in thickness (%) before and after heating is calculated, where the heated surface of the heat absorber is pressed at 0.5 MPa for 60 seconds".
8. A secondary battery module comprising: the heat absorber according to claim 1 or 2.
9. The secondary battery module according to claim 8, wherein the heat absorber is sandwiched between battery cells.

Description

TECHNICAL FIELD The present disclosure relates to a heat absorber and a secondary battery module including the heat absorber. BACKGROUND ART 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 problems such as ignition or smoke generation. Therefore, in order to minimize the damage due to such problems, 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. CITATION LIST PATENT LITERATURE PTL 1: WO2022/270359PTL 2: JP2020-161290A SUMMARY OF INVENTION TECHNICAL PROBLEM 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, there is a problem that the heat is easily transferred between the adjacent cells since a distance between the cells is shortened particularly when the cells expand. Therefore, an object of the present disclosure is to provide 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. SOLUTION TO PROBLEM The present inventors have found that a heat absorber containing an aqueous solvent and a water-soluble inorganic powder in a bag exhibits an excellent heat absorption property, heat insulation property, and pressure resistance, and can change into a heat insulator in a high temperature range (for example, 150°C or higher), and