Hierarchical Ternary MoO2/MoS2/Heteroatom-Doped Carbon Hybrid Materials for High-Performance Lithium-Ion Storage

Abstract

The synthesis and electrochemical lithium-ion storage behavior of hierarchical MoO2/MoS2/heteroatom-doped carbon (MoO2/MoS2/HD-C) ternary hybrid have been studied. This ternary hybrid is composed of ultrafine MoO2 nanowires and single/few-layer MoS2 encapsulated by heteroatom-doped carbon, constituting secondary cauliflower-like microspheres. The synthesis is achieved through the synergistic interplay of a polymer and an ionic liquid as structure-directing agents and carbon sources, using a solvothermal reaction followed by a simple thermal treatment. In this unique architecture, each component synergistically acts with a specific purpose. The HD-C matrix with abundant defects and vacancies provides fast electronic conduction as well as interfacial storage, and buffers the volume changes during charging/discharging processes. The ultrasmall dimensions of both MoO2 nanowires and single/few-layered MoS2 components enable rapid Li+ transport in all directions, which is of great benefit to the reversibility of “conversion” reactions. The hierarchical secondary structures assure the robust stability upon long-term cycling. The ternary hybrid material exhibits enhanced Li+-storage performance as well as reversible capacity, rate capability, and cycling stability. A high reversible specific capacity of 1147 mA h g−1 is delivered at 50 mA g−1 together with excellent cycling stability, and 841 mA h g−1 can be retained after 1000 cycles at 500 mA g−1.