Pseudocapacitive Lithium Storage in TiO₂(B)

Abstract

Phase-pure TiO2(B) with microfibrous morphology was prepared via a newly developed method from amorphous TiO2. Cyclic voltammetry evidences that Li-insertion into TiO2(B) is governed by a pseudocapacitive faradaic process, whose rate is not limited by solid-state diffusion of Li+ in a broad interval of scan rates. This unusual behavior was discussed in terms of the crystal structure of the TiO2(B) host, having freely accessible parallel channels for Li+-transport perpendicular to the (010) face. The characteristic Li-insertion electrochemistry of TiO2(B) allows re-interpretation of several previous reports, which did not consider explicitly this relation or the presence of TiO2(B) in various TiO2 materials of different origin.