The present disclosure relates to an azobenzene-graphene metal coordination solar photothermal energy storage material based on metal coordination bonds and a preparation method thereof. The method comprises the following steps: preparing reduced graphene oxide; preparing an azobenzene-graphene material; and preparing an azobenzene-graphene metal coordination solar photothermal energy storage material: dispersing the prepared azobenzene-graphene material in DMF, dissolving a certain amount of metal compound in DMF, adding the DMF solution of the metal compound into the DMF solution of the azobenzene-graphene, taking out the precipitate, washing off metal ions which do not participate in coordination, and drying the obtained product to obtain the azobenzene-graphene metal coordination solar photothermal energy storage material. The present disclosure also relates to a method for improving the solar photothermal energy storage ability of a molecular solar energy fuel, comprising using an azobenzene-graphene metal coordination solar photothermal energy storage material.

Composite material for thermochemical energy storage (TCES). The material comprises a salt hydrate that is impregnated into a matrix and encapsulated by a polymer. In some embodiments, the matrix is a gel matrix. In some embodiments, the gel matrix is silica gel. In some embodiments, the polymer is methylcellulose. In preferred embodiments, the impregnation and encapsulation are performed simultaneously. The material is created by mixing the components, stirring the mixture for a predetermined time, and drying the mixture at a predetermined temperature for a predetermined time.

Composite material for thermochemical energy storage (TCES). The material comprises a salt hydrate that is impregnated into a matrix and encapsulated by a polymer. In some embodiments, the matrix is a gel matrix. In some embodiments, the gel matrix is silica gel. In some embodiments, the polymer is methylcellulose. In preferred embodiments, the impregnation and encapsulation are performed simultaneously. The material is created by mixing the components, stirring the mixture for a predetermined time, and drying the mixture at a predetermined temperature for a predetermined time.

The invention is directed to a salt composition for use in a thermochemical energy storage device, said salt composition comprising a base and a hygroscopic salt that can produce a gas by reacting with an acid. In further aspects the invention is directed to ab energy storage compartment and a thermochemical energy storage device comprising the salt composition.

The invention is directed to a salt composition for use in a thermochemical energy storage device, said salt composition comprising a base and a hygroscopic salt that can produce a gas by reacting with an acid. In further aspects the invention is directed to ab energy storage compartment and a thermochemical energy storage device comprising the salt composition.

To provide a heat generating material in which a decrease in hydrogen absorption performance and amount of heat generation can be suppressed at the time of use at a high temperature, and physical properties such as hydrogen absorption performance and amount of heat generation are further improved.

The heat generating material includes: a first metal having a melting point of 230° C. or more; and a second metal having a melting point higher than the melting point of the first metal, in which, at this time, at least one of the first metal or the second metal has a hydrogen solubility greater than silver at a temperature less than the melting point of the second metal, a hydride of at least one of the first metal or the second metal has a standard enthalpy of formation equal to or more than a standard enthalpy of formation of CaH.sub.2, and heat is generated when the first metal and the second metal come into contact with hydrogen gas at a temperature less than the melting point of the second metal.

To provide a heat generating material in which a decrease in hydrogen absorption performance and amount of heat generation can be suppressed at the time of use at a high temperature, and physical properties such as hydrogen absorption performance and amount of heat generation are further improved.

The heat generating material includes: a first metal having a melting point of 230° C. or more; and a second metal having a melting point higher than the melting point of the first metal, in which, at this time, at least one of the first metal or the second metal has a hydrogen solubility greater than silver at a temperature less than the melting point of the second metal, a hydride of at least one of the first metal or the second metal has a standard enthalpy of formation equal to or more than a standard enthalpy of formation of CaH.sub.2, and heat is generated when the first metal and the second metal come into contact with hydrogen gas at a temperature less than the melting point of the second metal.

Provided are a chemical heat storage material having excellent cyclic durability and a method for producing the same. A chemical heat storage material includes: a surface layer formed of silica and/or calcium silicate; and calcium oxide particles with the surface layer.

Provided are a chemical heat storage material having excellent cyclic durability and a method for producing the same. A chemical heat storage material includes: a surface layer formed of silica and/or calcium silicate; and calcium oxide particles with the surface layer.

Compositions suitable for reversibly storing heat in thermal energy systems (TES) include a salt hydrate represented by the formula: MX.sub.q.nH.sub.2O. M is a cation selected from Groups 1 to 14 of the IUPAC Periodic Table, X is a halide of Group 17, q ranges from 1 to 4, and n ranges from 1 to 12. The cation (M) may have an electronegativity of ≤ about 1.8 and a molar mass ≤ about 28 g/mol. The anion (X) may have an electronegativity of ≥ about 2.9 to ≤ about 3.2. A distance between a cation (M) and coordinating water molecules (H.sub.2O) is ≤ about 2.1 Å. Thermal energy systems (TES) incorporating such compositions are also provided that are configured to reversibly store heat in the thermal energy system (TES) via an endothermic dehydration reaction and to release heat in in the thermal energy system (TES) via an exothermic hydration reaction.