Carbon-Free Cathodes: A Step Forward in the Development of Stable Lithium-Oxygen Batteries

Lithium-oxygen (Li-O-2) batteries are receiving considerable interest owing to their potential for higher energy densities than current Li-ion systems. However, the lack stability of carbon-based oxygen electrodes is believed to promote carbonate formation leading to capacity fade and limiting the cycling performance of the battery. To improve the stability and cyclability of these systems, alternative electrode materials are required. Metal oxides are mainly utilized at low current densities, whereas noble metals show outstanding performance at high current densities. Carbides appear to provide a good compromise between electrochemical performance and cost, which makes them interesting materials for further investigations. Here, a critical review of current carbon-free electrode research is provided with the goal of identifying routes to its successful optimization.