High‐Sulfur Loading and Single Ion‐Selective Membranes for High‐Energy and Durable Decoupled Aqueous Batteries

Abstract The decoupled battery design is promising for breaking the energy density limit of traditional aqueous batteries. However, the complex battery configuration and low‐selective separator membranes restrict their energy output and service time. Herein, a zinc–sulfur decoupled aqueous battery is achieved by designing a high‐mass loading sulfur electrode and single ion‐selective membrane (ISM). A vertically assembled nanosheet network constructed with the assistance of a magnetic field enables facile electron and ion conduction in thick sulfur electrodes, which is conducive to boosting the cell‐level energy output. For the tailored ISM, the Na ions anchored on its skeleton effectively prevent the crossover of OH⁻ or Cu²⁺, facilitating the transport of Na⁺ and ensuring structural and mechanical stability. Consequently, the Zn–S aqueous battery achieves a reversible energy density of 3988 Wh kg_s⁻¹ (by sulfur mass), stable operation over 300 cycles, and an energy density of 53.2 mWh cm⁻². The sulfur‐based decoupled system may be of immediate benefit toward safe, reliable, and affordable static energy storage.