High charge retention and optimization of polyaniline–titanium dioxide nanoparticles composite nanostructures for dominantly stable pseudocapacitive nature

Abstract

Abstract This work is conducted with the aim of improving overall specific capacity of polyaniline with incorporation of minimum amount of TiO2 nanoparticles where the structure could facilitate an efficient access to electrolyte ions to the electrode surface and shorten the ion diffusion path. The paper presents low temperature (0 to 5OC) in-situ synthesis scheme for Polyaniline (PANI) with very small (%wt) varying amount of titanium dioxide nanoparticles (nTiO2) for high performance supercapacitive nanocomposite electrode materials. PANI-nTiO2 composites are synthesized via standard in-situ chemical oxidative polymerization of aniline monomer in the presence of Hydrochloric Acid (HCl) as a dopant and Ammonium per Sulphate (APS) as an oxidant. The electrochemical analysis is carried out in a two-electrode geometry system. The redox supercapacitor cells using nanocomposite electrode materials are fabricated with diluted 0.1 M Sulphuric Acid (H2SO4) electrolyte. The highest claimed capacitance ~813 F/g at current density 1 mA/cm2 is obtained for the sample PT5 composite electrode with 5 wt% nTiO2 invariably due to the presence of thinner PANI nanofibers. This PT5 based symmetric supercapacitor device exhibits a high specific energy ~ 16.8 Whkg−1 at the maximum specific power ~ 9.75 Wkg−1. The PT5 symmetric nanocomposite sample showed no decay of capacitance till 2000 current charge/discharge cycles at a current density of 1 mA/cm2 in a potential window of 0.8 V. The decay (813 Fg−1 to 743 Fg−1) in capacitive value can be considered almost negligible. The presence of nTiO2 in small%wt in PANI composite enhances the specific capacitance claimed significantly as compared to its electric double-layer supercapacitor counterpart and is comparable to the reports available in this area. There is still a lot of scope to utilize these high performance nano-composite electrode materials with non-acidic electrolytes.