Engineering High-Performance Sulfur Electrode from Industrial Conductive Carbons

As part of sustainable development, lithiumsulfur (LiS) batteries exhibit great potential in grid energy storage and electrification applications, thanks to their high theoretical specific capacity, low cost, and environmental benignity. Compared to scattered reports on anode and electrolyte development, a huge effort in cathode research has led to the discovery of various new carbon materials with improved cell performance. Nevertheless, most of these carbons have cost issues with challenges in mass production, making their potential in practical LiS batteries lean. On the other hand, a wide range of industrial conductive carbons are available with varied specifications and could be a good source for LiS batteries if properly engineered. Herein, we systematically assessed 10 industrial conductive carbons and found one particularly suitable to the fabrication of high-performance sulfur cathode. The carbon has a moderately high specific surface area and good electrical conductivity, and a moderate adsorption capacity to polysulfides. With a small portion of the carbon substituted by single-walled carbon nanotubes, an effective conductive network forms in the resultant sulfur electrode, facilitating sulfur reduction and polysulfide oxidation in cell operations. Consequently, it renders a reduced voltage hysteresis, increased cell capacity, and uniform sulfur deposition in charge reaction on a mechanically enhanced electrode. At a sulfur content of 62.5 wt %, the cathode delivers a specific discharge capacity of 452 mA h g(-1) of electrode at 1C, corresponding to a high energy density of 840 W h kg(-1) (1.7 times that of LiCoO2 cathode). A capacity retention of 75% was seen after 300 dischargecharge cycles, proving the feasibility of using industrial carbons to fabricate high-performance sulfur electrode for practical LiS batteries.