Hybrid Li-Air Battery with Sulfuric Acid Electrolyte and Buckypaper Air Cathode

Li-air battery (LAB) with aqueous-based catholyte and a water-stable lithium electrode using a LISICON-type lithium ion conducting glass ceramic membrane can eliminate the problems of Li-air battery with organic electrolytes, such as air-breathing cathode choking and degradation of Li anode. We present a rechargeable dual-electrolyte hybrid Li-air battery (HyLAB) with outstanding discharging performances has been demonstrated. The HyLAB has sulfuric acid as the catholyte and has a large active electrode area of 10 cm². Two types of air-breathing cathode with active layer made from a buckypaper with 5 wt.% Pt supported on carbon nanotubes (Pt/CNTs) and 5 wt.% Pt on carbon black (Pt/CB) as electrocatalyst for oxygen reduction were prepared, and their cell discharge performances were also compared. The cell with Pt/CNTs showed a much better performance than the cell with Pt/CB at high current densities. A better performance of Pt/CNTs was attributed to the more open porous structures formed in the fibrous CNTs. The HyLAB with Pt/CNTs can achieve a discharging capacity of 306 mAh/g at a cut-off voltage of 3.15 V and current density of 0.2 mA/cm². The corresponding specific energy is 1067 Wh/kg based on the total weight of the sulfuric acid. Detailed results will be presented in this presentation.