CuO-ZnO heterojunction doped 2D ultrathin carbon nanosheet catalyzes rapid charge-transfer kinetics of lithium-sulfur batteries

Abstract

The polysulfide shuttle phenomenon and sluggish electrode kinetics impede the commercialization of Lithium-sulfur (Li-S) batteries. Heterogeneous structural materials possess adsorptive and catalytic properties. A flower-shaped CuO-ZnO heterojunction is deposited on 2D ultrathin carbon nanosheets (UC) as a capture center to immobilize and catalyze polysulfides. Polar p-type CuO immobilizes the polysulfides through polar-polar strong interaction. At the same time, n-type ZnO dots firmly anchor lithium ions and accelerate S8 → Li2S4 → Li2S, thus reducing the polarization of the electrode to ensure uniform Li nucleation and continuous smooth Li plating. The interfacial built-in electric field from ZnO to CuO of CuO-ZnO heterojunction achieves rapid conversing of lithium polysulfides (LiPSs). CuO-ZnO heterojunction promotes the kinetics of LiPSs-redox and the interfacial charge transfer. The battery with the heterojunction has a good discharge capacity in the long-term cycle, with a discharge specific capacity of 1282.08 mAh g−1 for the first cycle and 200 mAh g−1 for the 800th cycle at 0.5C. On the other hand, introducing a heterogeneous interface to solid electrolyte provides a fast and dynamic lithium-ion transport channel. This study offers a new strategy to enhance the electrochemical performances of Li–S batteries by combining heterogeneous interfaces.