Improving Lithium-Ion Half-/Full-Cell Performance of WO₃-Protected SnO₂ Core-Shell Nanoarchitectures

Anodes derived from SnO₂ offer a greater specific capacity comparative to graphitic carbon in lithium-ion batteries (LIBs); hence, it is imperative to find a simple but effective approach for the fabrication of SnO₂. The intelligent surfacing of transition metal oxides is one of the favorite strategies to dramatically boost cycling efficiency, and currently most work is primarily aimed at coating and/or compositing with carbon-based materials. Such coating materials, however, face major challenges, including tedious processing and low capacity. This study successfully reports a new and simple WO₃ coating to produce a core-shell structure on the surface of SnO₂. The empty space permitted natural expansion for the SnO₂ nanostructures, retaining a higher specific capacity for over 100 cycles that did not appear in the pristine SnO₂ without WO₃ shell. Using WO₃-protected SnO₂ nanoparticles as anode, a coin half-cell battery was designed with Li-foil as counter-electrode. Furthermore, the anode was paired with commercial LiFePO₄ as cathode for a coin-type full cell and tested for lithium storage performance. The WO₃ shell proved to be an effective and strong enhancer for both current rate and specific capacity of SnO₂ nanoarchitectures; additionally, an enhancement of cyclic stability was achieved. The findings demonstrate that the WO₃ can be used for the improvement of cyclic characteristics of other metal oxide materials as a new coating material.