Evidence of Intrinsic Pseudocapacitive Lithium Intercalation in Rutile TiNbO4

TiNbO4 is a recently discovered Li host material. Unlike most mixed oxides of Ti and Nb, TiNbO4 does not show a phase transformation for Li storage. It stores Li-ions via a purely single-phase reaction. In this work, we show that TiNbO4 stores Li-ions via intercalation pseudocapacitance in both bulk and nanostructured states. The rate performance and capacity of TiNbO4 are independent of nanostructuring, indicating that TiNbO4 stores charges through an intrinsic pseudocapacitance mechanism.