Physicochemical Properties of Oriented Crystalline Assembled Polyaniline/Metal Doped Li4Ti5O12 Composites for Li-ion Storage

Abstract

In this work, pure, doped Mg–, Mn–, and V-Li4Ti5O12, as well as polyaniline (PANI), and binary composites have been synthesized for supercapacitor applications. In situ, oxidation polymerization was used to create the nanocomposites. XRD, SEM, and XPS characterized the crystal structure, morphology, and compositions. The XRD analysis shows that all the pure and doped samples crystallize in the cubic spinel phase with a preferred orientation of the crystallites along the (111) direction, and the crystallite size has decreased with the addition of doping. The composites' SEM investigation revealed the production of LTO nanoparticles coated with PANI. The influence of dopant type on electrical and electrochemical characteristics was studied. The electrochemical performance is analyzed by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and impedance methods in a 1 M LiNO3 electrolyte solution, whereas their electrical conductivity and dielectric constant are measured by electric impedance spectroscopy. All samples showed conductivity and dielectric properties depending on the composition of the samples. The electrical conduction is enhanced by adding PANI to the pure and doped LTO samples. The electrochemical data obtained showed pseudo-capacitive behavior with a revisable charge/discharge property, and specific capacitance values lie between 58 and 202 F/g depending upon sample composition. The V-LTO@PANI demonstrates the highest performance among all the tested electrodes. The V-LTO@PANI electrode shows a specific capacitance of 202 F/g, a maximum energy density of 72.8 Wh/kg, a maximum power density of 2430 W/kg, and high cycling performance, with 82.6% capacitance retained over 3000 cycles at 1 A/g.