Ultrafast Al⁺ Conduction through Cooperative Bonding in Disordered Polycarbonate-Polyether Electrolytes.

As a new generation of high-energy-density energy storage system, solid-state aluminum-ion batteries have attracted much attention. Nowadays polyethylene oxide (PEO)-based electrolytes have been initially applied to Lithium-ion batteries due to their flexible processing and good interfacial compatibility, their application in aluminum-ion batteries still faces problems. To overcome the limitations in aluminum-ion batteries-specifically, strong Al coordination suppressing ion dissociation, high room-temperature crystallinity, and inadequate mechanical strength-this study develops a blended polymer electrolyte (BPE) of polypropylene carbonate (PPC) and PEO. The PPC disrupts PEO crystallization, creating continuous amorphous channels that boost Al mobility to 0.597 and enhance ionic conductivity. Simultaneously, rigid PPC chains form a dual-network structure with flexible PEO, increasing tensile strength to 672 kPa to effectively suppress aluminum dendrites. Crucially, PPC's carbonyl groups (─C═O) strongly adsorb Al (-1.49 eV), partially displacing PEO's ether-oxygen coordination. This decouples ion pairs, elevates free Al concentration, and improves interfacial kinetics. Consequently, Al//Al symmetric cells achieve stable 200-h cycling (0.1 mA cm, overpotential <0.4 V), and Al//benzo[i]benzo[6,7]quinoxalino[2,3,9,10]phenanthrol[4,5-abc]phenazine-5,10,16,21-tetraone (BQPT) cells retained 130 mAh g after 120 cycles at 1 A g, demonstrating a promising high-safety electrolyte.