Heterostructured poly(3,6-dithien-2-yl-9H-carbazol-9-yl acetic acid)/TiO2 nanoparticles composite redox-active materials as both anode and cathode for high-performance symmetric supercapacitor applications

Abstract

Herein, a facile and simple method is reported for preparation of composite electrode materials based on conducting polymer/nano metal oxide combination for supercapacitor applications. The heterostructured composite redox-active electrode materials, having both p- and n-doping ability, were fabricated using poly(3,6-dithien-2-yl-9H-carbazol-9-yl acetic acid) and nano sized TiO₂ particles without any binder and conducting additives. The heterostructured composite electrodes exhibited remarkable a specific capacitance (C_spec = 462.88 F g⁻¹), specific power (SP = 266.96 kW kg⁻¹), specific energy (SE = 89.98 W h kg⁻¹), good cycling performance and excellent reversible capability (81.7% capacitance retention after 8000 charge/discharge cycles) at 2.5 mA cm⁻² current density within a 1.2 V potential window with two-electrode symmetric cell configuration. Besides, heterostructured composite electrode materials were fabricated using different particle sized TiO₂ (3–5 nm, average 21 nm and bulk), and the effect of the particle size on supercapacitor performances was investigated and compared in detail. Our symmetric pseudo-capacitor device lighted a LED for 4.7 min with 42 s charge time at 2.5 mA cm⁻² even after 8000 charge/discharge cycles.