Enhanced cycle stability of rechargeable Li-O2 batteries using immobilized redox mediator on air cathode

Abstract Overcoming the low round-trip energy efficiency and poor cycle stability of lithium-oxygen (Li-O2) batteries still remains a challenge. Here, we show that 2,2,6,6,-tetramethylpiperidinyl-1-oxyl (TEMPO)-immobilized air cathode can effectively reduce the charge voltage and increase the cycle stability in Li-O2 batteries. The TEMPO-immobilized air cathode is prepared using a gas diffusion layer by a simple dip coating method, in which polydopamine is used as a linker. In this method, the immobilized TEMPO on the cathode does not crossover to the anode, and the consumption of TEMPO by side reactions is minimized. As a result, the redox mediation by TEMPO is well maintained in its immobilized state. This highlights that the use of an immobilized redox mediator can be a rational strategy for expanding the practical applications of Li-O2 batteries.