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

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-9Hcarbazol-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 twoelectrode 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.