Copper oxide supported on platinum nanosheets array: High performance carbon-free cathode for lithium–oxygen cells

Abstract

In this study, we present a new strategy on controlling the interaction between the Li2O2-catalyst interfaces through improving the affinity of catalyst surface towards Li2O2 molecules. A seed-mediated growth approach has been developed to synthesize Pt nanosheets on the stainless steel mesh using Fe as the seed. We further grow a uniform layer of metallic Cu nanoparticles on Pt nanosheets surface through electrochemical deposition. The Cu is converted to CuO by exposing it to air under ambient condition. Such strategy has effectively solved the problem of non-uniform deposition of CuO on Pt surface that arises from the poor interaction of oxides on metals. By converting the oxide-on-metal to metal-on-metal system, a relatively uniform of CuO can be successfully deposited on Pt nanosheets. The CuO on Pt provides multiple nucleation sites on the surface of the cathode, which facilitates the formation of Li2O2 thin layer in the discharge cycle. This process plays a crucial role in achieving a high round-trip efficiency of 88%, reversible specific capacity of 1648 mAh g−1 (683 mAh g−1 with respect to the total electrode mass including Li2O2) at 100 mA g−1 and maintains capacity retention of 98% during the 60th cycle at a high current density of 1 A g−1.