Enhanced performance of lithium-sulfur battery cathode via composition optimization using modified MWCNTs as a conductive material and poly (acrylic acid) as a binder

Abstract

Lithium–sulfur (Li–S) batteries are promising candidates for the next-generation energy storage devices for portable electronics and electric vehicles owing to their low-cost, high-energy density, and minimal environmental impact. However, low sulfur utilization and short life-cycle limit their performance and commercialization. Herein, Li–S battery cathodes were prepared by blending different proportions of active material sulfur (S) with modified multiwall carbon nanotubes (MWCNTs) as a conductive material, and poly (acrylic acid) (PAA) as a binder to optimize the electrode composition. Specially, we found that the oxidation of MWCNT improves not only their dispersion in water-based slurry during the electrode preparation but also improves the adsorption of lithium polysulfides during the electrochemical reaction. Cathode prepared with a 5:4:1 wt ratio of S: oxidized MWCNT: PAA shows the uniform dispersion of cathode slurry and exhibits the highest discharge capacity of ∼480 mA h g−1 when compared to other mixing ratios. This work demonstrates the feasibility of redox mediation to reinforce the electron accessibility with appropriately loaded sulfur on MWCNT.