Li_1 + xFe_1 − 3xTi_1 + 2x O ₄ (0.0 ≤ x ≤ 0.33) based spinels: possible negative electrode materials for future Li-ion batteries

Members of the spinel solid solution between LiFeTiO₄ and Li₄Ti₅O₁₂, i.e., Li_1+xFe_1-3xTi_1+2xO₄ (0.0≤x≤0.33) have been investigated as possible negative electrodes for future lithium-ion batteries. Electrochemical behavior and associated structural changes have been investigated over the potential range 0.01-2.6 V vs. Li⁺/Li. Results are promising with anodic capacities in excess of 200 mAh g^-1 or approximately 700 mAh cm^-3 being obtained over 25 cycles for x = 0.33. Samples containing Fe have reduced reversible capacity, however, the capacity below 1.00 V_Li is greatly increased. A spinel-type structure is retained upon lithiation for all compositions studied, however, the degree of cation disorder increases with Fe content.