Effect of surface fluorination and conductive additives on the electrochemical behavior of lithium titanate (Li 4/3Ti 5/3O 4) for lithium ion battery

Abstract

Effect of surface fluorination and conductive additives on the charge/discharge behavior of lithium titanate (Li 4/3Ti 5/3O 4) has been investigated using F 2 gas and vapor grown carbon fiber (VGCF). Surface fluorination of Li 4/3Ti 5/3O 4 was made using F 2 gas (3 × 10 4 Pa) at 25–150 °C for 2 min. Charge capacities of Li 4/3Ti 5/3O 4 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 Li 4/3Ti 5/3O 4 were 70 °C and 100 °C. Fibrous VGCF with a large surface area (17.7 m 2/g) increased the utilization of available capacity of Li 4/3Ti 5/3O 4 probably because it provided the better electrical contact than acetylene black (AB) between Li 4/3Ti 5/3O 4 particles and nickel current collector.