Orthorhombic Lithium Titanium Phosphate as an Anode Material for Li-ion Rechargeable Battery

Rhombohedral lithium titanium phosphate, LiTi2(PO4)3, has been considered a suitable anode material for aqueous lithium-ion batteries. However, the electrochemical behaviors of pure lithium-rich polymorphs have not been described yet even Li-rich phase may show better electrochemical properties than conventional LiTi2(PO4)3 at the expense of somewhat lowered capacity. We have synthesized orthorhombic Li1.5Ti2(PO4)3 (OLTP) and rhombohedral LiTi2(PO4)3 (RLTP) via sol-gel reactions and studied their fundamental electrochemical properties using galvanostatic charge/discharge and cyclic voltammetry (CV). Their feasibility as anode materials in LiFePO4//LixTi2(PO4)3 configurations using aqueous electrolytes were also considered. The faster kinetics of the orthorhombic lithium titanium phosphate in this study were attributed to higher Li+ diffusivity and electrical conductivity, making this material an attractive alternative for conventional rhombohedral LiTi2(PO4)3.