Freestanding Binder-Free Electrodes with Nanodisk-Needle-like MnCuCo-LTH and Mn1Fe2S2 Porous Microthorns for High-Performance Quasi-Solid-State Supercapacitors.

Abstract

Transition-metal-based layered triple hydroxides (LTHs) are evolving as potential positrode candidates for high-performance supercapacitors; however, their phase stabilization is still critical. Alongside, the availability of limited negatrodes pushes research toward exploring novel alternatives in order to minimize performance limitation issues in the fabricated supercapacitors. Herein, a facile strategy for stabilizing freestanding MnCuCo-LTH-based positrode possessing intermingled nanodisk-needle-like morphology is reported. Alongside, novel high-surface-area negatrodes based on Mn1Fe2S2 exhibiting porous microthorn-like morphology are also optimized. MnCuCo_LTH and Mn1Fe2S2 exhibit remarkably high specific capacities of ∼494 mAh g-1 (∼2540 F g-1) and ∼429 mAh g-1 (∼1546 F g-1), respectively, at 1 A g-1. The fabricated quasi-solid-state supercapacitor equipped with a poly(vinyl alcohol) (PVA)-KOH gel electrolyte displays a high specific capacity of ∼144 mAh g-1 and a specific capacitance of ∼325 F g-1 at 1 A g-1. The ultrahigh energy cum power traits of ∼105 Wh kg-1 (1 A g-1) and ∼8370 W kg-1 (at 10 A g-1) establish an asymmetric supercapacitor as a high-performance energy storage device. This device shows an appreciably high cycling life with a capacitance retention of ∼93% after 10 000 consecutive cycles, at 10 A g-1. This approach provides a neoteric foresight for developing high-performance advanced energy storage devices equipped with cheaper and eco-friendly components.