Method of manufacturing a metal-air cell
The invention includes a method of making a catalytic electrode for a metal-air cell in which a carbon-catalyst composite is produced by heating a manganese compound in the presence of a particulate carbon material to form manganese oxide catalyst on the surfaces of the particulate carbon, and then adding virgin particulate carbon material to the carbon-catalyst composite to produce a catalytic mixture that is formed into a catalytic layer. A current collector and an air diffusion layer are added to the catalytic layer to produce the catalytic electrode. The catalytic electrode can be combined with a separator and a negative electrode in a cell housing including an air entry port through which air from outside the container can reach the catalytic electrode.
1. A method of manufacturing a catalytic electrode for a metal-air cell, the method comprising the steps:
(a) providing a first particulate carbon material consisting essentially of carbon;
(b) providing a manganese compound;
(c) wet blending the first particulate carbon material and the manganese compound to form a blended intermediate mixture;
(d) drying the blended intermediate mixture at a first temperature below the thermal decomposition temperature of the manganese compound;
(e) producing a carbon-catalyst composite by heating the dried blended intermediate mixture to a thermal decomposition temperature of the manganese compound, at which the manganese compound thermally decomposes to form the carbon-catalyst composite comprising particles of manganese oxide on surfaces of particles of the first particulate carbon material;
(f) cooling the carbon-catalyst composite;
(g) producing a catalytic electrode mixture by combining the carbon-catalyst composite with a second particulate carbon consisting essentially of carbon;
(h) granulating, the catalytic electrode mixture; and
(i)forming a catalytic electrode comprising a layer of the catalytic electrode mixture, an electrically conductive current collector and an air diffusion layer, the air diffusion layer being secured to a surface of the layer of the catalytic mixture.
2. The method according to claim 1 , wherein each of the first and second particulate carbon materials is selected from activated carbon, carbon black, acetylene black, graphite, and meso-phase carbon.
3. The method according to claim 2 , wherein the first and second particulate carbon materials have the same composition.
4. The method according to claim 1 , wherein the manganese compound is at least one selected from: manganese (II) nitrate and potassium permanganate.
5. The method according to claim 4 , wherein the manganese compound is provided in a solution with a solvent and the solution is mixed with the first particulate carbon material.
6. The method according to claim 5 , wherein the solvent is removed prior to the step of heating the dried blended intermediate mixture to the thermal decomposition temperature.
7. The method according to claim 1 , wherein the manganese oxide comprises one or more manganese oxide compounds comprising one or more metal element dopants and has an overall formula MnO x (M), wherein x is from 0.5 to 2.0, and M is the one or more metal element dopants.
8. The method according to claim 7 , wherein M is selected from the group consisting of Au, Cu, Co, Ir, Ni, Pt, Ru.
9. The method according to claim 1 , wherein the manganese compound consists essentially of manganese (II) nitrate.
10. The method according to claim 1 , wherein the catalytic electrode mixture further comprises at least one binder selected from: a fluoropolymer, polytetrafluoroethylene, polyvinylidenefluoride, copolymers of hexafluoropropylene, fluorinated ethylene propylene, ultra high molecular weight polyethylene, ultra high molecular weight polypropylene, copolymers of ultra-high molecular weight polyethylene and copolymers of polypropylene.