Electrochemical conversion of natural graphite minerals into carbon nanostructures incorporated with Fe3Si for Li-ion storage application

Abstract

Natural graphite mineral (NGM) is an abundant and low-cost carbon source with the potential of being employed as the precursor for producing high-quality carbon nanostructures for energy storage applications. In this article, one-pot electrochemical conversion of NGM into graphitic carbon nanostructures incorporated with Fe3Si nanocrystals with enhanced bulk electrical conductivity and Li-ion storage performance is reported. To this end, electrodes made of NGM are negatively polarized in molten LiCl-NaCl at 740 °C under various cathode current densities. At 1 A cm−2, the high-yield conversion of the mineral into carbon nanotubes (CNTs), nanofibers and onion-like carbon nanoparticles is realized. The product exhibits a specific electrical conductivity of 9.83 S m2 g−1, and the Li+ transfer resistance of 24 Ω. The Li-ion storage capacity of the material is evaluated to be high at 382 mAh g−1 after 220 Li-ion insertion and extraction cycles under the current density of 200 mA g−1, making the material an attractive low-cost candidate for the anode of lithium ion batteries. The ferromagnetic behavior of the nanostructured Fe3Si incorporated carbon is characterized by the saturation magnetization of 11.1 emu g−1, potentially promoting the recyclability of spent anode material. This article reports on the green and low-cost conversion of NGMs into nanostructured carbon materials with enhanced Li-ion storage performance.