A high-performance hybrid supercapacitor with Li4Ti5O12-C nano-composite prepared by in situ and ex situ carbon modification

• Published in: Journal of solid state electrochemistry Vol. 16; no. 8; pp. 2791 - 2796
• Main Authors: Ni, Jiangfeng, Yang, Liuxiang, Wang, Haibo, Gao, Lijun
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.08.2012
• Subjects: Analytical Chemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Electrochemistry; Energy Storage; Original Paper; Physical Chemistry; Electrochemical performance; Lithium titanate; Hybrid supercapacitor; Activated carbon
• ISSN: 1432-8488; 1433-0768
• DOI: 10.1007/s10008-012-1704-9

In this work, we report on the synthesis of in situ and ex situ carbon-modified Li 4 Ti 5 O 12 -C (LTO-C) nano-composite and its application in a hybrid supercapacitor constructed using activated carbon (AC) and LTO-C nano-composite as positive and negative electrodes, respectively. The hybrid capacitors are characterized by galvanostatic charge–discharge, cycle life testing, and electrochemical impedance spectroscopy. The results reveal that the AC/LTO-C hybrid capacitors exhibit high rate capability and long cycle life. In the potential range of 1.5–3.0 V, the AC/LTO-C hybrid system can deliver a specific capacitance of 83 F g −1 based on the total mass of AC and LTO-C electrodes at a current density of 60 mA g −1 (2 C rate). At a higher discharge rate of 980 mA g −1 (32 C), the capacity is 68 F g −1 , about 82 % of that at 2 C rate. After 9,000 deep cycles at 32 C, the hybrid capacitor still maintains 84 % of its initial capacitance. The specific energy of such hybrid system is 20 Wh kg −1 , which is at least twice that of an AC/AC system. Combining the high energy density with power capability, the AC/LTO-C hybrid supercapacitor has demonstrated high performance for applications needing high power output.