Molten Salt Electrochemical Modulation of Iron-Carbon-Nitrogen for Lithium-Sulfur Batteries.

Abstract

Sulfur hosts with rationally designed chemistry to confine and convert lithium polysulfides are of prime importance for high-performance lithium-sulfur batteries. A molten salt electrochemical modulation of iron-carbon-nitrogen is herein demonstrated as formation of hollow nitrogen-doped carbon with grafted Fe3C nanoparticles (Fe3C@C@Fe3C), which is rationalized as an excellent sulfur host for lithium-sulfur batteries. Fe3C over nitrogen-doped carbon contributes to enhanced adsorption and catalytic conversion of lithium polysulfides. The sulfur-loaded Fe3C@C@Fe3C electrodes hence show a high capacity, good cyclic stability, and enhanced rate performance. This work highlights the unique chemistry of metal carbides on facilitating adsorption-conversion process of lithium polysulfides, and also extends the scope of molten salt electrolysis to elaboration of energy materials.