Electrical and Electrochemical Behavior of Binary Li_4Ti_5O_(12)-Polyaniline Composite

摘要

Polyaniline (PANI), and nanocrystallites of pure Li4Ti5O12 (LTO) and V-doped Li4Ti5O12 (V-LTO) spinel structure have been synthesized. The pure and doped Li4Ti5O12 was synthesized by solid-state reaction, whereas the samples containing PANI were prepared by the in-situ oxidation polymerization method. As-prepared materials were characterized by XRD, FT-IR and SEM techniques. The electrical and electrochemical properties were studied using impedance spectroscopy (EIS), cyclic voltammetry (CV), galvanostatic charge-discharge methods (GCD) techniques. The doping of LTO with vanadium caused marked changes in each of particle size, electrical conductivity, and electrical capacitance without any transforming in the spinel crystal structure of the LTO material. Electrochemical studies showed that the specific capacitance of a hybrid electrode built of the binary materials LTO and PANI is higher than that of its individual single material. It shows a specific capacitance of 108 F/g, an energy density of 30 Wh/kg, and a power density of 2160 W/kg at 4 A/g as well as high cycling performance, with 88.3% capacitance retained over 1000 cycles. The high electrochemical performance of the V-LTO/PANI composite electrode can be attributed to the synergistic effects of the singular constituents and the enhancement of electronic conduction in the hybrid electrode materials.