Preparation of pleated flower-like manganese-cobalt-silicate bimetallic electrode materials for supercapacitors

Abstract

Transition metal silicates (TMSS) have been studied as potential electrode materials for rechargeable batteries and supercapacitors (SCs), and delicate structural design can further enhance the capacity performance and cycling stability of TMSS electrode materials. Herein, a bimetallic doping modulation strategy was employed, and a novel metal-silicate structure was constructed to obtain SC anode materials with excellent electrochemical properties. Manganese cobalt silicate (AMMnCo) with a pleated flower-like structure was obtained by the reaction of Mn2+ and Co2+ with acid-etched montmorillonite (AM) substrates using a simple hydrothermal method. The benign, competitive bimetallic mechanism accelerates the growth of manganese silicate and cobalt silicate on treated montmorillonite (MMT), which results in more folded ion-transport channels on the lamellae and improves the electrochemical properties of the transition-metal silicates. AMMnCo exhibits a higher specific capacitance (979F·g−1/0.5 A·g−1) and better cycling performance (84 %/10,000 cycles) than its monometallic counterparts. Additionally, AMMnCo//AC (where AC is activated carbon), a hybrid supercapacitor (HSC) device, has a high mass specific capacitance and an energy density reaching 13.7 Wh·kg−1 at a power density of 246.9 W·kg−1. Therefore, AMMnCo is a prospective electrode material for high-performance SC applications.