Eliminating bandgap between Cu-CeO2-x heterointerface enabling fast electron transfer and redox reaction in Li-S batteries

Abstract

The design of catalyst systems with reasonable configuration to alleviate the shuttle effects and strength conversion kinetics of polysulfide (LiPSs) in lithium-sulfur (Li-S) batteries still remains a challenge. Herein, a novel Cu-CeO2-x heterointerface is constructed by an ion migrating-capturing process. The Cu2+dispersed inner the carbon nanofibers (CNF) is controlled released and transferred outside gradually, and finally is captured by the CeO2 nanoparticles anchored on the CNF surface and form a Cu-CeO2-x heterointerface. Synergistically, the CeO2 capture and disperse Cu clusters as a hosting material, while the Cu decoration prevent further aggregation of CeO2 at harsh reaction conditions. Thus, the orbital interaction between CeO2 and Cu induce numerous oxygen vacancy and band gap disappearance at the heterointerface, resulting in a lower energy barrier of electron/hole separation and fast electron transfer in the metallic Cu-CeO2-x composites. Eventually, the Cu-CeO2-x can accelerate the catalytic conversion of LiPSs and decomposition of Li2S, and the Li-S cell deliver an excellent performance of 626 mA h g−1 after 800 cycles at a current density of 2 C, with a decay rate of only 0.046 % per cycle. This work reveals the formation mechanism of oxygen vacancy and disappearance of band gap at heterointerface, opening up a new prospect for rational design of various heterogeneous structures for cathode materials.