Process for a Free-Standing and Stable All-Metal Structure for Symmetrical Lithium-Oxygen Batteries.

A number of inherent and thorny obstacles still stand in the way of the practical application of Li-O ₂ batteries, which require development of an advanced lithium anode and O ₂ cathode. Herein, the strategy of a symmetrical Li-O ₂ battery is presented. Specifically, Cu nanoneedle arrays with a nanoengineered Au coating are grown directly on a Cu foam substrate (Au/Cu@FCu), which can act as both the anode backbone and the cathode in a Li-O ₂ battery. The excellent conductivity, high porosity, large specific surface, and superior lithiophilicity as well as high catalytic activity of the Au/Cu@FCu electrodes can simultaneously regulate the deposition behavior of the lithium metal in the anode and catalyze the formation/decomposition of Li ₂ O ₂ in the cathode. As a result, the Li uniformly deposited on the Au/Cu@FCu anode without Li dendrites, showing a high Coulombic efficiency over 96% and a long and stable cycle lifetime over 970 h. At the same time, the Au/Cu@FCu cathode demonstrates extremely low overpotentials (0.64 V) and a much higher specific capacity of 27 270 mAh g ^-1 compared to the Li-O ₂ batteries with a carbon-free cathode reported to date. Moreover, the "ebb and flow" phenomenon of the anode and cathode morphology is also observed in the Li-O ₂ battery.