Lithium insertion into titanium phosphates, silicates, and sulfates

Ti-IV phosphates, sulfates, and silicates were investigated as positive electrodes in lithium batteries. We present the lithium insertion into TiSO5, LiTiPO5, Li(2)iSiO(5), TiP2O7, and ATi(2)-(PO4)(3) (A = Li, Na). The SO4, PO4, and SiO4 groups alter significantly the operating voltage due to the inductive effect on the Ti4+/Ti3+ redox couple lying around 2.5 V vs Li+/Li, i.e., similar to1 V higher than for simple titanium oxides such as spinel Li4Ti5O12 or Li4Ti5CrO4. Galvanostatic (GITT) and potentiostatic (PITT) intermittent titration techniques coupled with in situ X-ray diffraction were used to understand the lithium insertion mechanisms into these materials. Chemical lithiation was also performed on TiP2O7 and ATi(2)(PO4)(3) (A = Li, Na) to isolate new Ti-III-based compositions.