Bipolar battery electrode having improved carbon surfaces and method of manufacturing same
An electrode and a method of manufacturing an electrode for a flowing electrolyte battery enable improved robustness and reduced manufacturing costs of bipolar electrodes for flowing electrolyte batteries. The electrode includes a polymer sheet having a first side and a second side; a graphite layer on the first side; and an activated carbon layer on the second side.
1. A method of manufacturing an electrode for a flowing electrolyte battery, the method comprising:
coating a first side of a polymer sheet with a layer of graphite;
coating a second side of the polymer sheet with a layer of graphite and a layer of activated carbon, wherein the layer of activated carbon is on top of the layer of graphite on the second side;
pressing the polymer sheet, including both the layer of graphite and the layer of activated carbon, in a hot press;
pressing the polymer sheet, including both the layer of graphite and the layer of activated carbon, in a cold press subsequent to pressing in the hot press; and
removing the layer of activated carbon and the layer of graphite from a milled edge of the second side of the polymer sheet.
2. The method of claim 1 , wherein a temperature inside the hot press is between 130 and 280 degrees Celsius.
3. The method of claim 1 , wherein a pressure inside the hot press is 10 to 1000 bar.
4. The method of claim 1 , further comprising positioning a sheet of release paper adjacent the first side of the polymer sheet and positioning another sheet of release paper adjacent the second side of the polymer the polymer sheet during the pressing of the polymer sheet.
5. The method of claim 1 , further comprising coating the first side of the polymer sheet with a layer of activated carbon.
6. The method of claim 1 , further comprising bonding the polymer sheet to a polymer frame.
7. The method of claim 1 , wherein 0.5 to 25 grams of graphite per 1000 cm2 of surface area of the layer of graphite are coated on the first side of the electrode.
8. The method of claim 1 , wherein graphite in the layer of graphite is a powder having a particle size between 0.1 and 500 microns in diameter.
9. The method of claim 1 , wherein graphite in the layer of graphite is a powder having a particle size between 10 and 200 microns in diameter.
10. The method of claim 1 , wherein graphite in the layer of graphite is a powder having a particle size between 50 and 150 microns in diameter.
11. The method of claim 1 , wherein 0.5 to 50 grams of activated carbon per 1000 cm2 of surface area of the layer of activated carbon are coated on the second side of the electrode.
12. The method of claim 1 , wherein the layer of activated carbon is manufactured from one or more of the following: coconut shells, hardwood charcoal, bamboo charcoal and carbon black.
13. The method of claim 1 , wherein the polymer sheet comprises polyethylene made conductive by mixing it with conductive fillers.