In-situ generated sulfur/porous carbon nanocomposites featuring enhanced specific surface area for aqueous zinc-sulfur batteries with small electrochemical polarization

Abstract

Cathodes for aqueous zinc-sulfur batteries (AZSBs) produced via the conventional melt-infiltration technique face issues such as non-uniform sulfur distribution and a lack of active sites, which lead to sluggish redox reactions and considerable voltage hysteresis in AZSBs. In this study, we introduce an alternative approach where amorphous sulfur is encapsulated in situ within three-dimensional hierarchical porous carbons (S-HPCs). The versatility of this strategy is demonstrated by its applicability to various precursors. As a typical example, the resulting S-HPCs exhibits a significantly higher specific surface area of 494.4 m² g⁻¹, compared to the mere 6.4 m² g⁻¹ of cathode prepared via traditional melt-infiltration methods. This enhancement means an increase in active sites and an enlarged electrode-electrolyte interface, which in turn, accelerates electrode reaction kinetics. The S-HPCs cathode is capable of delivering a reversible capacity of 1493.4 mA h g⁻¹ at 0.5 A g⁻¹, with a narrowed polarization potential of just 0.42 V. They also demonstrate a high-rate performance of 849.2 mA h g⁻¹ at 5 A g⁻¹, along with enduring stability over 845 cycles at 5 A g⁻¹. This work not only presents a high-performance cathode for AZSBs but also offers strategies for enhancing the kinetics and cycle stability of AZSBs.