A completely sealed high temperature carbon-air battery with carbon dioxide absorber

Abstract A completely sealed high temperature carbon-air battery is proposed and prepared using a tubular oxygen-ion-conducting yttrium stabilized zirconia electrolyte with anode inside and cathode outside. CaO and carbon powders, with a molar ratio of 0.5, 0.75, and 1.0, are respectively loaded in the anode chamber, in two ways: One is mixing CaO and C together (mixing mode) and the other is loading them one by one (separating mode). The electrochemical output performance and discharging time of the batteries increase with decreasing CaO/C ratio. Thermodynamic calculation results show that the pressure of the anode chamber of a battery increases with more carbon oxidized. CO2 produced through the electrochemical oxidation of carbon can be absorbed by CaO to produce CaCO3, resulting in relieve of pressure. However, insufficient CO2 for maintaining the operation of battery is also caused by CaO. This evidence may be mitigated by loading C and CaO separately to avoid immediate reaction between CO2 and CaO. A carbon-air battery with 0.25 g carbon powder separately loaded with CaO in a CaO/C ratio of 0.5 discharges at 200 mA for 6.9 h, giving a practical specific energy density of 1300 Wh kg−1, considering the mass of both C and CaO.