Synergistic Integration of Soluble Catalysts with Carbon-Free Electrodes for Li-O-2 Batteries

Abstract

The instabilities associated with solid catalysts and carbon electrode materials are one of the challenges that prevent Li-O-2 batteries from achieving a truly rechargeable high energy density. Here, we seek to achieve reversible Li-O-2 battery operations with high energies by tackling these instabilities. Specifically, we demonstrate synergistic integration of dual soluble catalysts (2,S-di-tert-butyl-1,4-benzoquinone (DBBQ) for discharging and (2,2,6,6-tetramethylpiperidin-l-yl)oxyl (TEMPO) for charging) with antimony tin oxide (ATO) noncarbon electrodes with a porous inverse opal structure. The dual soluble catalysts showed a synergistic combination without any negative interference with each other, leading to higher capacity and rechargeability. Moreover, noncarbon porous antimony tin oxide (pATO) cathodes guaranteed improved stability against catalyst degradation, while KB carbon electrodes severely threatened stability of the soluble catalysts during cycling. We also found that the surface properties of the electrodes influenced the discharge mechanism, even in the presence of a solution-phase growth promoter such as DBBQ, which implies that further interface engineering may improve the performance. This study shows the great potential of the integration of soluble catalysts with electrode materials for further improvements in capacity, energy efficiency, and rechargeability for the practical development of Li-O-2 batteries.