Pseudocapacitance-Enhanced Li-Ion Microbatteries Derived by a TiN@TiO2 Nanowire Anode

Titaniumdioxide (TiO2) has been studied extensively as a stable, cheap, and safe anode material for Li-ion batteries. However, the inherent sluggish Li-ion diffusion and particularly poor electronic conductivity limit its practical applications. Here, we report a core/shell TiN/TiO2 nanowire array to tackle these problems. The single-crystal-like TiN nanowire cores function as highly conductive nanostructured current collectors, and the branched shell is constructed by nanoporous anatase TiO2 mesocrystals. This 3D nanoarray electrode exhibits a pseudocapacitity-dominated charge storage of lithium ions with outstanding performance in terms of high areal and volumetric capacity, fast chargedischarge ability, and long cycling lifetime. Charge transport through the unique nanoporous TiO2 mesocrystal shells and the high-conductivity TiN nanowire core account for the superior performance.