Aqueous decoupling batteries: Exploring the role of functional ion-exchange membrane

Abstract

The relentless pursuit of sustainable and safe energy storage technologies has driven a departure from conventional lithium-based batteries toward other relevant alternatives. Among these, aqueous batteries have emerged as a promising candidate due to their inherent properties of being cost-effective, safe, environmentally friendly, and scalable. However, traditional aqueous systems have faced limitations stemming from water's narrow electrochemical stability window (~1.23 V), severely constraining their energy density and viability in high-demand applications. Recent advancements in decoupling aqueous batteries offer a novel solution to overcome this challenge by separating the anolyte and catholyte, thereby expanding the theoretical operational voltage window to over 3 V. One key component of this innovative system is the ion-selective membrane (ISM), acting as a barrier to prevent undesired crossover between electrolytes. This review provides a comprehensive overview of recent advancements in decoupling aqueous batteries, emphasizing the application of various types of ISMs. Moreover, we summarize different specially designed ISMs and their performance attributes. By addressing the current challenges ISMs face, the review outlines potential pathways for future enhancement and development of aqueous decoupling batteries.