Metal hydride-air (MH-AIR) battery for low cost storage applications
Metal hydride-air batteries and methods for their use are provided. An exemplary metal-hydride air battery includes an alkaline exchange membrane provided between the positive electrode and the negative electrode of the battery. The alkaline exchange membrane provides for transfer of hydroxide ions through the membrane. Optionally the alkaline exchange membrane limits transport of other species through the membrane.
1. A metal hydride-air battery comprising:
a positive electrode, wherein the positive electrode is an air electrode comprising an electrocatalyst, wherein the electrocatalyst is one of an oxygen reduction reaction catalyst and an oxygen evolution catalyst and the battery further comprises a second electrocatalyst, the second electrocatalyst being the other of an oxygen reduction reaction catalyst and an oxygen evolution catalyst;
a negative electrode, wherein the negative electrode is a hydrogen absorbing material, wherein the hydrogen absorbing material is an intermetallic compound comprising a component A and a component B, wherein component A is selected from the group consisting of La, Ce, Ti, and combinations thereof and B is selected from the group consisting of Ni, Co, Mn, Al and combinations thereof;
an electrolyte provided between said positive electrode and negative electrode, said electrolyte being capable of conducting hydroxide charge carriers; and
an alkaline exchange membrane comprising an ionomer polymer electrolyte, wherein said alkaline exchange membrane is chemically stable for an electrolyte pH from 10 to 14, provided between said positive electrode and said negative electrode; wherein said alkaline exchange membrane restricts transport of O 2 from said positive electrode to said negative electrode during charging or discharging of said battery, and
wherein said positive air electrode, said electrocatalyst, and said alkaline exchange membrane are in physical contact with the alkaline exchange membrane.
2. The metal hydride-air battery of claim 1 , wherein said hydrogen absorbing material is an amorphous material.
3. The metal hydride-air battery of claim 1 , wherein a source of O 2 is provided in contact with said positive electrode and said source of O 2 is air.
4. The metal hydride-air battery of claim 1 , wherein said alkaline exchange membrane functions as a substrate to support said electrocatalyst of said positive electrode.
5. The metal hydride-air battery of claim 1 , wherein said electrolyte is an aqueous alkaline electrolyte.
6. The metal hydride-air battery of claim 5 , wherein said aqueous alkaline electrolyte comprises a source of hydroxide ion dissolved in a solvent, said source of hydroxide ion selected from the group consisting of KOH, NaOH, and any combination of these.
7. The metal hydride-air battery of claim 6 , wherein said source of hydroxide ion has a concentration in said solvent selected from the range 1M to 6M.
8. The metal hydride-air battery of claim 1 comprising a closed system.
9. A method of generating electrical current, said method comprising:
providing a metal hydride battery comprising:
a positive electrode, wherein the positive electrode is an air electrode comprising an electrocatalyst, wherein the electrocatalyst is one of an oxygen reduction reaction catalyst and an oxygen evolution catalyst and the battery further comprises a second electrocatalyst, the second electrocatalyst being the other of an oxygen reduction catalyst and an oxygen evolution catalyst in contact with a source of O 2 ;
a negative electrode, wherein the negative electrode is a hydrogen absorbing material, wherein the hydrogen absorbing material is an intermetallic compound comprising a component A and a component B, wherein component A is selected from the group consisting of La, Ce,Ti and combinations thereof and B is selected from the group consisting of Ni, Co, Mn, Al and combinations thereof;
an electrolyte provided between said positive electrode and negative electrode, said electrolyte capable of conducting hydroxide charge carriers; and
an alkaline exchange membrane comprising an ionomer polymer electrolyte, wherein said alkaline exchange membrane is chemically stable for an electrolyte pH from 10 to 14, provided between said positive electrode and said negative electrode; wherein said alkaline exchange membrane restricts transport of O 2 from said positive electrode to said negative electrode during discharging of said battery; and wherein said positive air electrode, said electrocatalyst, and said alkaline exchange membrane are in physical contact with the alkaline exchange membrane; and
discharging said battery thereby generating electrical current.
10. A method of storing electrical current, said method comprising:
providing a metal hydride battery comprising:
a positive electrode, wherein the positive electrode is an air electrode comprising an electrocatalyst, wherein the electrocatalyst is one of an oxygen reduction reaction catalyst and an oxygen evolution catalyst and the battery further comprises a second electrocatalyst, the second electrocatalyst being the other of an oxygen reduction reaction catalyst and an oxygen evolution catalyst;
a negative electrode, wherein the negative electrode is a hydrogen absorbing material, wherein the hydrogen absorbing material is an intermetallic compound comprising a component A and a component B, wherein component A is selected from the group consisting of La, Ce, Ti and combination thereof and B is selected from the group consisting of Ni, Co, Mn, Al and combinations thereof;
an electrolyte provided between said positive electrode and negative electrode, said electrolyte capable of conducting hydroxide charge carriers; and
an alkaline exchange membrane comprising an ionomer polymer electrolyte, wherein said alkaline exchange membrane is chemically stable for anelectrolyte pH from 10 to 14, provided between said positive electrode and said negative electrode; wherein said alkaline exchange membrane restricts transport of O 2 from said positive electrode to said negative electrode during charging of said battery; wherein said positive air electrode, said electrocatalyst, and said alkaline exchange membrane are in physical contact with the alkaline exchange membrane; and
charging said battery by flowing current into said battery thereby storing said current as chemical energy.
11. The metal hydride-air battery of claim 1 , wherein component A is a rare earth element and component B is Ni with the general stoichiometry of AB 5 .
12. The metal hydride-air battery of claim 1 , wherein the metal hydride-air battery has a volumetric energy density greater than 300 Whr/l.
13. The metal hydride-air battery of claim 1 , wherein the metal hydride-air battery has a gravimetric energy density greater than 150 Whr/kg.