Facile Synthesis of Capacitive Carbon Materials via Electrolyzing Carbonates Eutectic with Varying Metallic Anodes

Abstract

The protocol of molten salts electrolysis provides a feasible close-loop solution to yield CO2 reduction and mitigate global climate change. In the present study, a typical Li2CO3-Na2CO3-K2CO3 eutectic is employed as the electrolyte and the electrolysis is performed in a two-electrode system. Three metallic materials of galvanized iron, nickel and copper are utilized as the counter electrode and assembled with the working electrode of galvanized iron in the molten salts electrolyzer to prepare electrolytic carbons. It is verified here that the hybrid carbonates electrolysis prefers the production of amorphous carbons with varying carbon structures. In particular, the electrochemical performance of the carbon products is studied in aqueous H2SO4 solution, and the carbon materials formed in Ni anode electrolyzer exhibit an ultrahigh specific capacity of 336 F/g at the charge/discharge current density of 1000 mA/g. Besides, current efficiency, reaction kinetics and electricity consumption for per kilogram carbon production are evaluated. The results demonstrate that the Ni anode electrolyzer provides the lowest voltage and electricity consumption, and simultaneously the maximum carbon deposition rate and current efficiency during the galvanostatic electrolysis process.