Two-dimensional spinel CuCo2S4 nanosheets as high efficiency cathode catalyst for lithium-oxygen batteries

In this work, a novel 2D CuCo2S4 (CCS) nanosheets with spinel type structure is fabricated and used as the cathode catalyst for rechargeable Li-O2 battery. The characteristic 2D nanosheets structure with exposure of special (113), (004), and (044) crystal faces provide sufficient active sites for ORR and OER, which promote the rate capability immensely as well as improve discharge capacity and cycle life of the battery. Specifically, Li-O2 batteries with CCS electrodes show excellent cycle stability of more than 176 cycles at limiting capacity 500 mA h g−1 and superior rate performance (2254 mA h g−1 at 2000 mA g−1). For comparison, nanostructures of CuS and Co3S4 have been synthesized employing the similar process used for CCS. When compared to conventional carbon material (Super P) and these two binary metal sulfides, CCS NSs provided the highest catalytic activities at the same mass loading. Which can be attributed to the introduction of copper in the Co3S4 lattice offers the oxygen evolution and kinetics by enhancing Cu2+ sites and also by providing a high-active high-spin stat of octahedral Co3+ for ORR and OER catalysis.