The demand for portable rechargeable energy storage devices is ever increasing, especially because of the advent of electric vehicles and widespread usage of portable electronics. The Li-ion batteries are used ubiquitously; however, the high-cost and shortage of Li storage are stimulating the search for alternative technologies. The room temperature sodium sulfur batteries (RT Na-S) is a technologically viable alternative candidate which possesses astounding advantages such as low cost, non–toxicity, natural abundance, and high theoretical energy density (1274 Whkg-1). However, the inevitable problems such as the solubility of higher order polysulfides to the electrolyte, known as shuttle effect, and the sluggish kinetics of electrochemical conversion reactions of intermediate sodium polysulfides (NaPS) significantly impede the practical realization of Na-S batteries. The conventionally used various forms of carbonaceous nanomaterials for cathode design have floundered to overcome the challenges. The polar anchoring materials (AM) have exhibited promising performance to improve sulfur chemistry. It is generally understood that catalytic performance is directly connected to the surface area of catalytic particles, and the single-atomic level provides the maximum surface area, resulting in the highest catalytic efficacy. Herein, we use first principles-based density functional theory (DFT) simulations to investigate the interfacial interactions between NaPS and novel transition metal (TM) single-atom catalysts (SACs) embedded on nitrogen doped graphene and various lattice sites of transition metal chalcogenides (TMD). We demonstrate that SACs possess strong adsorption strength with the NaPS which are superior to the commonly used ether electrolyte solvents, a requisite to prevent shuttle effect. We illustrate the influence of d-band center of SACs as an important descriptor in describing NaPS interactions with the AMs. We investigate the effect of SACs on improving the kinetics of sulfur reduction reactions (SRRs) and catalytic decomposition of short-chain polysulfides which are crucial for achieving excellent rate capability. Overall, the insights obtained on the role of SACs in tailoring the polysulfides redox chemistry at the interfaces and their relation to their TM’s d-band center is an important step towards rational design cathode materials for high-performance Na-S batteries, in particular, but metal-chalcogenide batteries, in general.

Design principles of bifunctional single-atom electrocatalyst for engineered interfaces in Na-S batteries

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