Lamellar Carbon Composited Cobalt Iron Silicate with a Two-Dimensional Structure Toward Enhanced Electrochemical Properties for Supercapacitors

Abstract

Transition metal silicates are a potential supercapacitor electrode material due to appreciable theoretical specific capacitance and high energy density. However, the inherent narrow voltage window range and poor conductivity lead to unsatisfactory electrochemical properties. Herein, the carbon composited iron cobalt silicate (denoted as CHOAMFC) with a two-dimensional lamellar structure is designed to enhance the electrical conductivity, where two-dimensional mesoporous silica obtained from montmorillonite was used as the silicon source and template to combine with Fe2+ and Co2+. The CHOAMFC exhibits a specific capacitance of 1008.3 F·g–1 at 0.5 A·g–1 with a long lifespan of 107% after 10 000 cycles. Meanwhile, the assembled hybrid supercapacitor device (CHOAMFC//AC) displays the energy density of 50.9 W h·kg–1 at 275 W·kg–1 as well as excellent cycling stability after 7000 cycles. The great supercapacitor performance is attributed to the uniformly distributed secondary nanosheets on the lamellar substrate that enhance the exposure of sites and the contact with the electrolyte, allowing for easier ion transport. This study explores a strategy of CHOAMFC based on the resource endowment and crystal structure of natural minerals, which provides a feasible idea to obtain two-dimensional layered bimetallic silicate supercapacitor electrode materials with excellent electrochemical performance.