A CoOx/carbon double-layer thin film air electrode for nonaqueous Li-air batteries

A double-layer structural air cathode consisting of diamond like carbon (DLC) active layer and CoOx catalytic layer is designed and its catalytic effect for Li-air batteries both in carbonate and ether based electrolytes are tested. Ethylene carbonate (EC)/dimethyl carbonate (DMC) based Li-air cell using this double-layer electrode as air cathode exhibits significant improvement in discharge/charge electrochemical performance but suffers from electrolyte decomposition as proved by Fourier transform infrared (FTIR) and secondary ion mass spectrometry (SIMS) measurements. In 1,2-dimethoxyethane (DME) based electrolyte, CoOx/DLC double layer electrode shows high catalytic activity towards oxygen evolution reaction (OER). Furthermore, over 30 cycles is achieved with a capacity of more than 2000 mAh g−1 by using CoOx/DLC double layer electrode, which makes it a promising air electrode for Li-air batteries.

► A CoOx/diamond like carbon (DLC) double layer thin film electrode was fabricated.
► We examined electrochemical properties of CoOx/DLC electrode for Li-air batteries.
► CoOx/DLC electrode exhibited a bifunctional catalytic activity for Li-air batteries.
► Spatial distribution of discharge products were investigated by SIMS.
► Bifunctional effect of CoOx layer for Li-air battery was revealed.