Trigonal selenium nanocrystallites decorated cellulose-polyaniline composite as a potential supercapacitor electrode material

Abstract

Despite the pseudocapacitive nature of polyaniline electrode materials, low power density and poor cyclic stability make them undesirable for efficient supercapacitor applications. Herein, trigonal selenium nanocrystallites decorated cellulose/polyaniline composites are prepared through freeze-drying-assisted room temperature polymerization. All Se/cellulose/PANI composites have similar interconnected fibrillar morphology, which facilitates effective conduction of electrons. Se improves the thermal stability of Se-cellulose-PANI by crystallizing in a trigonal form with crystallites that range in size from 4 to 6 nm. While the presence of Se nanocrystallites offers many ion-accessible active areas and short diffusion paths, cellulose provides outstanding cyclic stability to the material. Among the composites studied, the Se-cellulose-PANI composite demonstrates a noticeable areal capacitance and specific capacitance of 4.55 F/cm² and 238.33 F/g at a sweep rate of 2 mV/s. Furthermore, it exhibits remarkable cyclic stability as it retains 100 % of initial capacitance even after 5000 cycles of charge-discharge. Additionally, the symmetric supercapacitors assembled with Se-cellulose-PANI composites have a high energy density of 0.087 mWh/cm² and a power density of 10 mW/cm². Even after 50,000 cycles, the supercapacitor has an excellent capacitance retention value of 99 %. The outcome supports the indefectible potential of the Se-cellulose-PANI composite and favours the development of efficient solid-state energy storage devices.