A positive electrode active material precursor is provided, which includes a transition metal hydroxide particle represented by Formula 1 and a cobalt oxide particle and a manganese oxide particle attached to the surface of the transition metal hydroxide particle. A preparation method thereof, a positive electrode active material prepared using the same, a positive electrode including the positive electrode active material, and a secondary battery including the positive electrode are also provided.

Disclosed is an α-phase nickel hydroxide and a preparation method and use thereof. The method for preparing an α-phase nickel hydroxide comprises the following steps: subjecting a biomass calcium source to a calcination to obtain a porous calcium oxide; under a protective atmosphere, mixing the porous calcium oxide with a first methanol-ethanol solvent to obtain a calcium oxide heterogeneous solution; under a protective atmosphere, mixing the calcium oxide heterogeneous solution with a nickel source homogeneous solution to obtain a mixture, and subjecting the mixture to a coprecipitation to obtain a nickel calcium hydroxide precursor, wherein the nickel source homogeneous solution is prepared with a nickel source containing crystal water as a solute and a second methanol-ethanol solvent as a solvent; and subjecting the nickel calcium hydroxide precursor to a calcium hydroxide removal treatment to obtain the α-phase nickel hydroxide.

Disclosed is an α-phase nickel hydroxide and a preparation method and use thereof. The method for preparing an α-phase nickel hydroxide comprises the following steps: subjecting a biomass calcium source to a calcination to obtain a porous calcium oxide; under a protective atmosphere, mixing the porous calcium oxide with a first methanol-ethanol solvent to obtain a calcium oxide heterogeneous solution; under a protective atmosphere, mixing the calcium oxide heterogeneous solution with a nickel source homogeneous solution to obtain a mixture, and subjecting the mixture to a coprecipitation to obtain a nickel calcium hydroxide precursor, wherein the nickel source homogeneous solution is prepared with a nickel source containing crystal water as a solute and a second methanol-ethanol solvent as a solvent; and subjecting the nickel calcium hydroxide precursor to a calcium hydroxide removal treatment to obtain the α-phase nickel hydroxide.

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.

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.

A positive electrode active material precursor is provided, which includes a transition metal hydroxide particle represented by Formula 1 and a cobalt oxide particle and a manganese oxide particle attached to the surface of the transition metal hydroxide particle. A preparation method thereof, a positive electrode active material prepared using the same, a positive electrode including the positive electrode active material, and a secondary battery including the positive electrode are also provided.

The invention relates to a method for producing a metal chalcogenide thin film electrode, comprising the steps: (a) contacting a metal or metal oxide with an elementary halogen in a non-aqueous solvent, producing a metal halide compound in the solution, (b) applying a negative electric voltage to an electrically conducting or semiconducting substrate which is in contact with the solution from step (a), and (c) during and/or after step (b) contacting the substrate with an elementary chalcogen forming a metal chalcogenide layer on the substrate. The invention also relates to a metal chalcogenide thin film electrode which can be produced by the method and its use as an anode for releasing oxygen during (photo)electrochemical water splitting.

The invention relates to a method for producing a metal chalcogenide thin film electrode, comprising the steps: (a) contacting a metal or metal oxide with an elementary halogen in a non-aqueous solvent, producing a metal halide compound in the solution, (b) applying a negative electric voltage to an electrically conducting or semiconducting substrate which is in contact with the solution from step (a), and (c) during and/or after step (b) contacting the substrate with an elementary chalcogen forming a metal chalcogenide layer on the substrate. The invention also relates to a metal chalcogenide thin film electrode which can be produced by the method and its use as an anode for releasing oxygen during (photo)electrochemical water splitting.

Disclosed is an -phase nickel hydroxide and a preparation method and use thereof. The method for preparing an -phase nickel hydroxide comprises the following steps: subjecting a biomass calcium source to a calcination to obtain a porous calcium oxide; under a protective atmosphere, mixing the porous calcium oxide with a first methanol-ethanol solvent to obtain a calcium oxide heterogeneous solution; under a protective atmosphere, mixing the calcium oxide heterogeneous solution with a nickel source homogeneous solution to obtain a mixture, and subjecting the mixture to a coprecipitation to obtain a nickel calcium hydroxide precursor, wherein the nickel source homogeneous solution is prepared with a nickel source containing crystal water as a solute and a second methanol-ethanol solvent as a solvent; and subjecting the nickel calcium hydroxide precursor to a calcium hydroxide removal treatment to obtain the -phase nickel hydroxide.

Disclosed is an -phase nickel hydroxide and a preparation method and use thereof. The method for preparing an -phase nickel hydroxide comprises the following steps: subjecting a biomass calcium source to a calcination to obtain a porous calcium oxide; under a protective atmosphere, mixing the porous calcium oxide with a first methanol-ethanol solvent to obtain a calcium oxide heterogeneous solution; under a protective atmosphere, mixing the calcium oxide heterogeneous solution with a nickel source homogeneous solution to obtain a mixture, and subjecting the mixture to a coprecipitation to obtain a nickel calcium hydroxide precursor, wherein the nickel source homogeneous solution is prepared with a nickel source containing crystal water as a solute and a second methanol-ethanol solvent as a solvent; and subjecting the nickel calcium hydroxide precursor to a calcium hydroxide removal treatment to obtain the -phase nickel hydroxide.