Fabrication of Sulfur- Aerogel-based Cathode Materials via Aqueous Wet Coating Method and Their Electrochemical Evaluation Against Magnesium Anodes

Abstract

Magnesium-sulfur (Mg–S) batteries have attracted quite important attention because of the fact that they are promising energy storage systems with a high theoretical energy density (~1722 Wh kg⁻¹) and naturally abundant magnesium [1,2]. Magnesium anodes offer safety improvements. Lithium-ion batteries exhibit greater dendrite formation [2]. Sulfur is known as an attractive cathode material because of the fact that it has a high theoretical capacity (1672 mAh g⁻¹), a low cost, and environmental friendliness [3]. These features allow for Mg–S batteries to store some clean energy and enable more electric mobility applications. Magnesium-sulfur batteries do greatly attract attention because of how they promise a high theoretical energy density near 1722 Wh kg⁻¹, also because magnesium naturally abounds in terms of energy storage systems [1,2]. Lithium-ion batteries have more dendrite creation so magnesium anodes provide better safety [2]. Sulfur is a cathode material of interest since it has a high theoretical capacity (1672 mAh g⁻¹). In addition, sulfur has a low cost coupled with its environmentally friendly nature [3]. These features do allow for Mg–S batteries to store clean energy and also enable electric mobility applications. However, for the commercialization of Mg–S batteries, it is not without some obstacles. Several challenges stand against this process. The insulating nature of sulfur, the shuttle effect, soluble polysulfides lead to active material loss, and sluggish Mg²⁺ ion kinetics in the cathode limit performance [3,4]. Therefore, it is critical that cathode architectures develop in a way that they effectively confine sulfur while maintaining structural stability. Therefore, developing cathode architectures that can effectively confine sulfur and maintain structural stability is critical. Highly porous carbon aerogel matrices have recently gained attention for their ability to homogeneously disperse sulfur and physically trap polysulfides [5,3]. Carbon aerogels provide high surface area, adjustable microstructure, high pore volumes, and excellent conductivity, enhancing ion and electron transport within the cathode, thus improving Mg–S battery performance [5,3]. In this work, environmentally friendly sulfur-aerogel-based cathodes were fabricated using an aqueous wet coating method with CMC/SBR binders, known for providing flexibility and adhesion [6]. The cathode films were thinned by calendering and the aerogel structure effectively trapped sulfur, minimizing polysulfide loss. Electrochemical tests were performed in pouch cells using a Mg metal anode and a Mg[B(hfip)₄]₂ electrolyte developed by KIT [1,7]. The cells exhibited initial discharge capacities exceeding 420 mAh gS⁻¹ at C/20 and maintained stable cycling performance over 60 cycles without sulfur loss.