Embedded coral reef sponge like structured Al(OH)3/FeOOH composite for flexible solid-state symmetric supercapacitor

Abstract Designing and fabricating a battery type supercapacitor with high electrical conductivity and good electrocapacitive performance is necessary to improve the energy storage. In this work, a battery type Al(OH)3/FeOOH composite supercapacitive electrode has been deposited on stainless steel substrate through a facile, economical and binder free layer by layer method. A mesoporous nanostructured morphology has been observed using HRSEM and HRTEM while FTIR analysis of samples confirmed the composite formation. Further, the XPS has been performed to explain the chemical and electronic states present within sample. The electrochemical analysis of the Al(OH)3/FeOOH electrode shows high specific capacity of 2576C g−1 at scan rate of 5 mV s−1 in 1 M Na2SO4 as well as it has a low solution resistance (~1.335 Ω). A prototype flexible symmetric supercapacitor has been fabricated through coating of PVA-Na2SO4 gel electrolyte. The observed specific capacitance of 255 F g−1 with energy density of 75 W h Kg−1 at power density 1035 W kg−1 has been attributed to coral reef sponge like mesoporous nanostructured morphology of deposited films, in turn, resulting in low contact resistance and fast ion transportation. Our study suggests that Al(OH)3/FeOOH composite is a potentially promising electrode material for portable energy storage applications.