Ultrafast Al3⁺ Conduction through Cooperative Bonding in Disordered Polycarbonate-Polyether Electrolytes.

Abstract

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 Al³⁺ 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 Al³⁺ 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 Al³⁺ (-1.49 eV), partially displacing PEO's ether-oxygen coordination. This decouples ion pairs, elevates free Al³⁺ concentration, and improves interfacial kinetics. Consequently, Al//Al symmetric cells achieve stable 200-h cycling (0.1 mA cm^-2, 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^-1 after 120 cycles at 1 A g^-1, demonstrating a promising high-safety electrolyte.