Dataset of "Glue-assisted Exfoliation of Two-dimensional Sulfur-rich Niobium Thiophosphate (Nb4P2S21) for Sulfur-equivalent Electrode Study in Lithium Storage"

Two-dimensional (2D) layered thiophosphates have garnered attention for advanced batteries due to their open ionic diffusion channels, high capacity, and unique catalytic properties. However, their potential in energy storage applications remains largely unexplored. In this study, we report for the first time a 2D transition metal thiophosphate (Nb4P2S21) with high sulfur content. Nb4P2S21, synthesized via chemical vapor transport (CVT), is treated as a sulfur-equivalent material with better conductivity than sulfur, suitable for high-capacity lithium storage. The bulk material can be delaminated into high-quality nanoplates via glue-assisted grinding exfoliation, both displaying a layered quasi-one-dimensional (quasi-1D) morphology, which shortens the ion diffusion path and promises enhanced rate performance compared to larger lateral 2D materials. Density functional theory (DFT) calculations indicate that Nb4P2S21 has a direct bandgap of 1.64 eV (HSE06 method), with exfoliated counterparts showing near-infrared (NIR) photoluminescence at 755 nm, broadening potential applications to NIR-based devices. By tuning the working voltage window for lithium-ion batteries (LIBs) and controlling lithiation product formation, the material exhibits distinct electrochemical characteristics at 0 ~ 2.6 V, 0.5 ~ 2.6 V, 1.0 ~ 2.6 V, and 1.5 ~ 2.6 V. However, sulfur-rich electrodes in carbonate electrolytes demonstrate limited electrochemical potential due to polysulfide formation, leading to detrimental side reactions with carbonate-based electrolytes. Transitioning to ether-based electrolytes improves the initial reversible capacity and Coulombic efficiency of Nb4P2S21 by stabilizing the formed polysulfides. Despite this improvement, the material still mirrors the shuttle effect in lithium-sulfur batteries, diminishing active sulfur and undermining battery integrity. Further EDS and TOF-SIMS analyses of post-cycled electrode materials show significant sulfur loss and precipitation within the electrodes, exacerbating the shuttle effect and causing battery failure. Implementing strategies used in lithium-sulfur batteries, such as introducing polar host catalysts, could enhance the potential of these materials.