Effect of surface fluorination and conductive additives on the electrochemical behavior of lithium titanate (Li4/3Ti5/3O4) for lithium ion battery

Effect of surface fluorination and conductive additives on the charge/discharge behavior of lithium titanate (Li4/3Ti5/3O4) has been investigated using F2 gas and vapor grown carbon fiber (VGCF). Surface fluorination of Li4/3Ti5/3O4 was made using F2 gas (3 × 104 Pa) at 25–150 °C for 2 min. Charge capacities of Li4/3Ti5/3O4 samples fluorinated at 70 °C and 100 °C were larger than those for original sample at high current densities of 300 and 600 mA/g. Optimum fluorination temperatures of Li4/3Ti5/3O4 were 70 °C and 100 °C. Fibrous VGCF with a large surface area (17.7 m2/g) increased the utilization of available capacity of Li4/3Ti5/3O4 probably because it provided the better electrical contact than acetylene black (AB) between Li4/3Ti5/3O4 particles and nickel current collector.