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. CO 2 produced through the electrochemical oxidation of carbon can be absorbed by CaO to produce CaCO 3 , resulting in relieve of pressure. However, insufficient CO 2 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 CO 2 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. • Carbon-air battery with C as anode active material and CaO as CO 2 absorber. • Battery based on YSZ electrolyte with the anode chamber completely sealed. • CaO relieves anode pressure but causes insufficient CO 2 for maintaining operation. • Loading CaO and C separately can mitigate the negative effect of CaO. • Battery with CaO and C separately loaded in a molar ratio of 0.5 gives 1300 Wh kg −1 .