Reciprocated electrochemical and DFT investigations of iron selenide: mechanically bendable solid-state symmetric supercapacitor

Enhanced energy storing capability with the aid of unique nanostructured morphology is beneficial to enrich the effective path for the development of energy storing capability of supercapacitors. Scheming earth abundant and low-cost transitional metal selenides (TMSs) with enhanced charge transfer capability with pronounced stability is still a challenge. Herein, state of art is presented for iron selenide with nanoflakes surface architecture synthesized with aid of simple, industry-scalable, and ionic layer controlled chemical approach namely; successive ionic layer adsorption and reaction (SILAR) method. Iron selenide electrode yields capacitance of 671.7 F/g at 2 mV/s scan rate and 434.6 F/g at 2 mA/cm2 current density through cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) studies, respectively with 91.9% cyclic retention at 4000 cycles. Developed bendable solid-state supercapacitor reveals remarkable power density of 5.1 kW/kg with outstanding deformation tolerance including practical demo to run small fan, demonstrating capability for advanced energy storage applications. Complementary first-principles Density Functional Theory (DFT) approach used to achieve reciprocity with experimental supercapacitive performance through the understandings of the electronic structure