Constructing epitaxially grown heterointerface of metal nanoparticles and manganese dioxide anode for high-capacity and high-rate lithium-ion batteries.

Low ion migration rate and irreversible change in the valence state in transition-metal oxides limit their application as anode materials in Li-ion batteries (LIBs). Interfacial optimization by loading metal particles on semiconductor can change the band structure and thus tune the inherent electrical nature of transition-metal oxide anode materials for energy applications. In this work, Au nanoparticles are epitaxially grown on MnO2 nanoroads (MnO2-Au). Interestingly, the MnO2-Au anode shows excellent electrochemical activity. It delivers high reversible capacity (about 2-3 fold compared to MnO2) and high rate capability (740 mA h g-1 at 1 A g-1). The electron holography and density functional theory (DFT) results demonstrate that the Au particles on the surface of MnO2 can form a negative charge accumulation area, which not only improves the Li ion migration rate but also catalyzes the transition of MnOx to Mn0. This study provides a direction to heterointerface fabrication for transition-metal oxide anode materials with desired properties for high-performance LIBs and future energy applications.