An Amorphous Polyimide-Based Positive Electrode for High-Capacity and Durable Aluminum Dual-Ion Batteries.

Redox-active organic electrode materials have emerged as promising and sustainable candidates for high-performance rechargeable aluminum-ion batteries (RABs). However, their practical applications are hindered by sluggish diffusion kinetics stemming from the large steric hindrance of bulky chloroaluminate ions within the densely packed crystalline lattices, as well as severe capacity fading caused by undesirable structural stability in the electrolyte. Herein, we present an amorphous polymerization strategy to construct high-capacity polyimide-based positive electrode materials for stable aluminum-polymer batteries via rational imidization molecular structure design. Benefiting from the amorphous structure with a large surface area, enhanced active site accessibility, and improved structural stability, the polyimide-based positive electrodes deliver a high specific capacity (191 mAh g-1 at 50 mA g-1), an improved rate capability (135 mAh g-1 at 500 mA g-1), and prolonged long-term cycling stability (95% capacity retention over 2400 cycles at 1 A g-1). The superior electrochemical performance is attributed to the amorphization-facilitated bipolar-redox charge storage mechanism, in which imide carbonyl groups (AlCl2 + coordination mechanism) and extended conjugated polycyclic aromatic hydrocarbons (AlCl4 - adsorption mechanism) alternately serve as redox-active sites within the polyimide segments. These findings highlight a molecular imidization strategy for designing active polymeric materials to construct robust polymer-based RABs for safe energy storage.