Hybrid electrolyte with biomass-derived carbon host for high-performance aqueous Zn–S battery

Abstract

The aqueous Zinc-Sulfur battery (AZSB) utilizes earth-abundant zinc anode along with sulfur cathode, making it a low-cost and safe alternative with decent energy density. In order to tackle the side reactions at the cathode and anode, a hybrid electrolyte is developed by incorporating dimethyl carbonate (DMC) as a co-solvent and iodine as an additive. Incorporating an optimal amount of dimethyl carbonate (DMC) in the aqueous electrolyte does not compromise the conductivity and non-flammability of the AZSB system, yet brings effective changes to the solvation shell of the zinc ions, reducing the free water activity and thus, limiting the water-based side reactions. In addition, the hybrid electrolyte is found to improve the wettability of the sulfur cathode which enhances the reaction kinetics at the cathode. To support the hybrid electrolyte, a low-cost porous carbon material derived from waste jackfruit peel biomass is employed as the sulfur host on the cathode. Combining hybrid electrolyte and biomass-derived porous carbon–sulfur composite allows for an exceptional performance in AZSB, i.e., a capacity of 1167 mAh gS−1 at 0.1 A gS−1, along with an energy density of 502 Wh kgS−1. Even at a high rate of 1 A gS−1, the battery is able to retain 47.6 % capacity after 200 cycles. This innovative electrolyte design, coupled with the incorporation of an inexpensive porous carbon host, significantly enhances the Zn/S electrochemistry, showcasing the immense potential of AZSB for future applications.