High-entropy oxides

Patent metadata

Field	Value
Publication number	US-2025145462-A1
Application number	US-202318837301-A
Country	US
Kind code	A1
Filing date	Feb 9, 2023
Priority date	Feb 9, 2022
Publication date	May 8, 2025
Grant date	—

Abstract

Disclosed are high-entropy oxides, and methods of their preparation. The high-entropy oxide is characterised by a sub-micron particle size and rod-like particle shape. The method of its preparation includes a co-precipitation step, preferably using an oxalate compound as a precipitating agent. Also disclosed are an electrode, e.g. an anode, a catalyst and an electrochemical cell comprising the high-entropy oxide.

First claim

What is claimed is:

1 . A method of preparing a high-entropy oxide, the method comprising:
(a) mixing a solution comprising at least four elementally different metal cations in a solvent, each metal cation making up at least 5% of the total number of the four or more elementally different metal cations, with a precipitating agent to obtain a solid material comprising the at least four metal cations; (b) thermally treating the solid material to obtain a high-entropy oxide;
wherein the precipitating agent comprises an organic anion.

2 . The method of claim 1 , wherein the thermal treatment includes a calcining process to produce a high-entropy oxide intermediate.

3 . The method of claim 2 , wherein the thermal treatment includes annealing the high-entropy oxide intermediate to obtain the high-entropy oxide.

4 . The method of claim 3 , wherein the high-entropy oxide intermediate is mixed with a solid-state dispersant before annealing.

5 . The method of any one of claims 1 to 4 , wherein the thermal treatment includes the use of a controlled atmosphere.

6 . The method any one of claims 1 to 5 , wherein the solution comprises at least five elementally different metal cations.

7 . The method of any one of claims 1 to 6 , wherein each metal cation is independently selected from the group consisting of cations of Be, Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Gd, Pb and Pt.

8 . The method of any one of claims 1 to 7 , wherein the metal cations are independently selected from the group consisting of cations of Mg, Co, Ni, Cu and Zn.

9 . The method of any one of claims 1 to 8 , wherein the metal cations are independently selected from the group consisting of cations of Mg, Mn, Fe, Co and Ni.

10 . The method of any one of claims 1 to 9 , wherein the precipitating agent is an oxalate compound.

11 . The method of any one of claims 1 to 10 , wherein the solvent comprises water and ethylene glycol.

12 . The method of claim 10 or 11 wherein the oxalate compound is ammonium oxalate.

13 . A method of preparing a high-entropy oxide, the method comprising:
(a) mixing a solution comprising at least four elementally different metal cations in a solvent, each metal cation making up at least 5% of the total number of the four or more elementally different metal cations, with a precipitating agent to obtain a solid material comprising the at least four metal cations; (b) thermally treating the solid material to obtain a high-entropy oxide intermediate; (c) mixing the high-entropy oxide intermediate with a solid-state dispersant and annealing the high-entropy oxide intermediate to form the high-entropy oxide.

14 . An oxalate salt comprising four or more elementally different metal cations, each metal cation making up at least 5% of the total number of metal cations.

15 . The oxalate salt of claim 14 , wherein each metal cation makes up between 5% and 30% of the total number of metal cations.

16 . The oxalate salt of claim 14 or 15 , in the form of particles comprising the four or more elementally different metal cations.

17 . The oxalate salt of any one of claims 14 to 16 , wherein each metal cation is independently selected from the group consisting of cations of Be, Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Gd, Pb and Pt.

18 . The oxalate salt of any one of claims 14 to 17 , comprising a rod-like particle shape.

19 . The oxalate salt of claim 18 , wherein the length:width ratio of the particles is between about 1:1.5 to about 1:3.5.

20 . The oxalate salt of any one of claims 14 to 19 , represented by the formula (A v B w C x D y E z )C 2 O 4 , wherein v, w, x, y and z are each independently about 0.05 to about 0.30, and wherein A, B, C, D, and E are each independently selected from the group consisting of cations of Be, Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn, Gd, Pb and Pt.

Assignees

• Auckland Uniservices Ltd

Inventors

• Cao Peng
• Pu Yuguang

Classifications

• C01P2006/40

  Electric properties · CPC title

• C01P2004/04

  obtained by TEM, STEM, STM or AFM · CPC title

• C01P2004/03

  obtained by SEM · CPC title

• C01P2002/88

  by thermal analysis data, e.g. TGA, DTA, DSC · CPC title

• C01P2002/72

  by d-values or two theta-values, e.g. as X-ray diagram · CPC title