The peculiar size and temperature dependence of water diffusion in carbon nanotubes studied with 2D NMR diffusion–relaxation D  – T 2eff spectroscopy

Gkoura, L.; Diamantopoulos, G.; Fardis, M.; Homouz, D.; Alhassan, S.; Beazi-Katsioti, M.; Karagianni, M.; Anastasiou, A.; Romanos, G.; Hassan, J.; Papavassiliou, G.

doi:10.1063/5.0005398

Abstract This study presents a new material, “H_xCrS₂” (denotes approximate composition) formed by proton‐exchange of NaCrS₂which has a measured capacity of 728 mAh g⁻¹with significant improvements to capacity retention, sustaining over 700 mAh g⁻¹during cycling experiments. This is the highest reported capacity for a transition metal sulfide electrode and outperforms the most promising proposed sodium anodes to date. H_xCrS₂exhibits a biphasic structure featuring alternating crystalline and amorphous lamella on the scale of a few nanometers. This unique structural motif enables reversible access to Cr redox in the material resulting in higher capacities than seen in the parent structure which features only S redox. Pretreatment by proton‐exchange offers a route to materials such as H_xCrS₂which provide fast diffusion and high capacities for sodium‐ion batteries.

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