Cobalt orthosilicate as a new electrode material for secondary lithium-ion batteries.

Herein, cobalt orthosilicate (Co2SiO4, CSO) is presented as a new electrode material for rechargeable lithium-ion batteries. Orthorhombic α-Co2SiO4 (space group: Pbnm) was synthesized by a conventional solid-state method and subsequently characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). To study the reversible lithium uptake and release, cyclic voltammetry (CV), in situ XRD, as well as ex situ X-ray photoelectron spectroscopy (XPS) and SEM analysis were performed. Based on these results a new reaction mechanism is proposed including the reversible formation of lithium silicate. In addition, the electrochemical performance of CSO-based electrodes was investigated by galvanostatic cycling, applying varying specific currents. Such electrodes revealed a good high rate capability and a highly reversible cycling behavior, providing a specific capacity exceeding 650 mAh g(-1) after 60 cycles.