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.

Montmorillonite-based materials for electrochemical energy storage

“…G. Tian's group employed a bimetallic doping modulation strategy to synthesize functional metal silicates as SC electrodes through the reaction between transition metal ions (Mn 2+ /Co 2+ and Fe 2+ /Co 2+ ) and acid-etched MMT under facile hydrothermal conditions. 161,162 Initially, a bimetallic silicate of Mn and Co (AMMnCo) with a plicated flower-like architecture (Fig. 11e) was synthesized.…”

“…For further improving the electronic conductivity of the transition metal silicate composites, a 2D lamellar structural composite consisting of carbon and iron-cobalt silicate was synthesized and an improved specific capacitance of 1008.3 F g −1 at 0.5 A g −1 and a higher capacity retention of 107% over 10 000 cycles were achieved. 162 3.3.2 MMT-derived electrode materials. MMT-derived electrode materials generally include the silicon-based materials prepared with MMT as the precursor and the carbon-based materials prepared with MMT as the template or nanoreactor.…”

“…For further improving the electronic conductivity of the transition metal silicate composites, a 2D lamellar structural composite consisting of carbon and iron-cobalt silicate was synthesized and an improved specific capacitance of 1008.3 F g −1 at 0.5 A g −1 and a higher capacity retention of 107% over 10 000 cycles were achieved. 162…”

Mn‐doping ensuring cobalt silicate hollow spheres with boosted electrochemical property for hybrid supercapacitors

“…They attract scientists for their low cost, high theoretical capacity, ease of preparation, and stable structure. [14][15][16][17][18][19][20][21][22][23][24][25] For instance, Pang and colleagues conducted a study in which they utilized SiO 2 @Ni(SO 4 ) 0.3 (OH) 1.4 nanobelts as the template to prepare cobalt-nickel silicate via a hydrothermal route. The asymmetric SC assembled by cobalt-nickel silicate and graphene sheets exhibited the specific capacitance of 981 F g −1 at 0.7 A g −1 in about 0~0.4 V. 17 His group also synthesized N,S co-doped 3D carbon-Co 3 Si 2 O 5 (OH) 4 composite from the biomass bamboo leaves.…”

“…Transition metal silicates (TMSs) have received significant attention and are considered one of the most popular electrode materials for high‐performance supercapacitors (HSCs) in the past few decades. They attract scientists for their low cost, high theoretical capacity, ease of preparation, and stable structure 14–25 . For instance, Pang and colleagues conducted a study in which they utilized SiO 2 @Ni(SO 4 ) 0.3 (OH) 1.4 nanobelts as the template to prepare cobalt‐nickel silicate via a hydrothermal route.…”