2D CdPS3-based versatile superionic conductors

Abstract

Ion transport in nanochannels is crucial for applications in life science, filtration, and energy storage. However, multivalent ion transport is more difficult than the monovalent analogues due to the steric effect and stronger interactions with channel walls, and the ion mobility decreases significantly as temperature decreases. Although many kinds of solid ionic conductors (SICs) have been developed, they can attain practically useful conductivities (0.01 S cm−1) only for monovalent ions above 0 °C. Here, we report a class of versatile superionic conductors, monolayer CdPS3 nanosheets-based membranes intercalated with diverse cations with a high density up to ∼2 nm−2. They exhibit unexpectedly similar superhigh ion conductivities for monovalent (K+, Na+, Li+) and multivalent ions (Ca2+, Mg2+, Al3+), ∼0.01 to 0.8 S cm−1 in the temperature range of −30 ‒ 90 °C, which are one to two orders of magnitude higher than those of the corresponding best SICs. We reveal that the high conductivity originates from the concerted movement of high-density cations in the well-ordered nanochannels with high mobility and low energy barrier. Our work opens an avenue for designing superionic conductors that can conduct various cations and provides possibilities for discovering unusual nanofluidic phenomena in nanocapillaries.