Layered titanate hierarchical spheres as a promising pseudocapacitive electrode material for high rate lithium ion batteries

Abstract

Layered titanates with large interlayer spacing (ca. 0.8–0.9 nm) facilitate Li+ movement with less resistance, and are considered suitable anode materials for high power lithium ion batteries (LIBs). Herein, lepidocrocite-type titanate hierarchical spheres (W-THSs) assembled by nanowires are synthesized by supercritical hydrothermal treatment of sodium peroxotitanate complex solution and subsequent acid washing. Nanowire components in the W-THSs interpenetrate each other to form a mesoporous network with high specific surface area (183.6 m2 g−1), which provides electrolyte penetration channels, enlarged electrode/electrolyte contact area, and short charge transport path, favoring fast Li+ insertion/extraction. Consequently, W-THSs exhibits an excellent electrochemical performance, giving a high discharge capacity of 123.6 mAh g−1 even at 5.0 A g−1, and still retaining 180.8 mAh g−1 after 500 cycles at 1.0 A g−1. The rate capability of W-THSs is much superior to the compared anatase TiO2 hierarchical spheres (AHSs) obtained by calcining W-THSs in the air. Moreover, cyclic voltammetry analyses reveal that a pseudocapacitive process occurs during the Li+ storage in W-THSs, significantly contributing to the excellent rate capability.