Multifunctional Ion/Electron‐Conductive Interlayers for Enhanced Solid‐State Aluminum Batteries

Abstract Non‐aqueous rechargeable aluminum batteries (RABs) have emerged as promising next‐generation energy storage systems owing to their inherent advantages of abundant resource availability, high theoretical capacity, and superior operational safety. Nevertheless, critical challenges persist in conventional RABs employing chloroaluminate ionic liquid electrolytes (ILEs) and high‐capacity metal selenide cathodes, particularly regarding aluminum dendrite formation and pronounced shuttle effects. To address these challenges, an innovative solid‐state battery architecture is proposed incorporating an ionic‐electronic dual‐conductive interlayer (NCIL) strategically positioned between a gel polymer electrolyte (GPE) and a conversion‐type CuSe cathode. Combined experimental investigations and theoretical analyses demonstrate that the rationally designed NCIL serves triple functions: 1) effectively confining soluble intermediates to enhance active material utilization efficiency, 2) modulating ion transport characteristics by increasing the anion transference number ( t = 0.30), thereby promoting reaction kinetics, and 3) suppressing aluminum dendrite proliferation. As a consequence, the optimized Al|GPE/NCIL|CuSe configuration delivers an ultrahigh specific capacity of 1438 mAh g ⁻¹ at 0.1 A g ⁻¹ and efficiently operates over 5000 cycles at 1.0 A g ⁻¹ , markedly outperforming both conventional liquid‐state (Al|ILE|CuSe) and solid‐state (Al|GPE|CuSe) counterparts. This interfacial engineering strategy establishes a new paradigm for developing durable, high‐energy‐density aluminum‐based energy storage systems through synergistic electrolyte‐electrode interface optimization.