Engineering sub-2 nm ion-selective membranes for advancing energy generation technologies

Abstract

Ion-selective membranes are critical components in energy generation technologies, including osmotic energy generators, flow batteries, and light-induced energy generators. These systems rely on membranes that can selectively transport specific ions while effectively excluding others, directly influencing overall efficiency. This review comprehensively summarizes recent advancements in ion-selective membranes with sub-2 nm pore sizes and enhanced ion selectivity for high-efficiency energy generation. We first explore the nanomaterials used in the fabrication of these membranes, along with their respective synthesis methods. Furthermore, we categorize membrane ion selectivity into cation/anion selectivity, mono-/divalent ion selectivity, and specific-ion selectivity while providing an overview of their selective mechanisms. Finally, we discuss how membrane ion selectivity influences energy generation performance and outline strategies to improve membrane efficiency.