Manipulating electrocatalytic activity of carbon architecture by supercritical carbon dioxide foaming and defect engineering for Li–S chemistry

Abstract Lithium–sulfur batteries (LSBs) have engendered extensive investigation interests owing to their remarkable theoretical capacity and energy density. Nevertheless, LSBs suffer from issues of fatal polysulfide (PS) shuttle and retarded sulfur redox reaction kinetics, impeding their real implementation. In this work, we report a delicate design of melamine formaldehyde resin-derived carbon architecture (CA) with manipulated electrocatalytic activity for Li–S chemistry by synergizing a versatile supercritical carbon dioxide (sc CO2) foaming technique and tailored defect engineering. The superior redox reaction kinetics for PSs afforded by the as-designed active CA resulting from the comprehensive management of hierarchical pore structure, surface area, nitrogen content and vacancy defect degree are demonstrated by our systematic electrochemical measurements and synchrotron X-ray three-dimensional nano-computed tomography (X-ray 3D nano-CT) results. As expected, the cathode shows a low decay of 0.06% per cycle at 1.0 C for 800 cycles. Impressively, even at a high sulfur loading of 9.3 mg cm−2 and a low electrolyte usage of 4.0 μL mgS−1, the cathode still delivers a remarkable specific capacity of 913.9 mA h g−1 as well as an outstanding retention of 86.3% at 0.1 C after 50 cycles.