Preparation and Characteristics of Li4Ti5O12 Anode Material for Hybrid Supercapacitor

Spinel-$Li_4Ti_5O_{12}$ was successfully synthesized by a solid-phase method at 800, 850, and $900^{\circ}C$ according to the $Li_4Ti_5O_{12}$ cubic spinel phase structure. To achieve higher EDLC energy density with the $Li_4Ti_5O_{12}$, the negative electrode of the hybrid supercapacitor was studied in this work. The electrochemical performances of the hybrid supercapacitor and EDLC were characterized by constant current discharge curves, c-rate, and cycle performance testing. The capacitance (1st cycle) of the hybrid supercapacitor and EDLC was 209 and 109 F, respectively, which is higher than EDLC. The capacitance of the hybrid supercapacitor decreases from 209 F to 101 F after 20 cycles when discharged at several specific current densities ranging from 1 to 10 A. In contrast, capacitance of the EDLC hardly decreases after 20 cycles. Results show that hybrid supercapacitor benefits from the high rate capability of supercapacitor and high capacity of the battery. Findings also prove that the hybrid supercapacitor is an energy storage device where the supercapacitor and the Li ion secondary battery coexist in one cell system.