Tailoring organic phenazine-carbon anodes for high-performance aqueous rechargeable batteries.

Abstract

Organic phenazine derivatives have emerged as promising materials for aqueous rechargeable batteries (ARBs) owing to their high theoretical capacity, molecular tunability and low cost. However, their practical application is largely constrained by poor intrinsic electronic conductivity and severe dissolution-induced capacity fading. Herein, a versatile dissolution-reprecipitation strategy is developed to construct highly integrated organic‑carbon nanocomposites for fast and durable aqueous K⁺ storage. Nano-sized dipyridophenazine (DPPZ) is conformally reprecipitated on Ketjen Black (KB), yielding a composite with intimate interfacial coupling and continuous electron pathways. As a result, the composite delivers exceptional high-rate capability and unprecedented cycling stability, retaining 99.9% of its initial capacity over 55,000 cycles at 50 A g^-1. Operando spectroscopic analyses, combined with density functional theory (DFT) calculations, reveal a highly reversible CN-K⁺ coordination mechanism, which governs the outstanding electrochemical behavior. Furthermore, full batteries employing Ni(OH)₂ cathodes deliver a high discharge capacity of 113 mAh g^-1 at 50 A g^-1 along with long-term durability, demonstrating record-level high-rate capability in aqueous K⁺ batteries. This work establishes a general and scalable strategy for advanced organic electrodes, offering a viable pathway toward safe, low-cost, and long-lifetime aqueous energy storage systems.