Tailoring Quinone-Based Organic Small Molecules as Universal Cathodes for High-Performance Zn/Al-Ion Batteries Operating From −50 to 50°C

Aqueous multivalent Zn- and Al-ion batteries offer intrinsic safety and high theoretical capacities, yet the high charge density of Zn²⁺ and Al³⁺ leads to sluggish kinetics and structural instability in inorganic intercalation cathodes. Organic cathodes present a promising alternative due to their coordination-driven redox chemistry, yet the practical deployment is limited by the high solubility of small molecules. Conventional strategies like polymerization and hybridization fail to balance stability, redox activity, and energy density. Here, we adopt an intrinsic small-molecule design strategy and develop a quinone-based small molecule, NQNT, that integrates adjacent carbonyl (C═O) and imine (C═N) groups within a rigid conjugated backbone to maximize redox-site accessibility, suppress dissolution, and enable stable multivalent-ion coordination. As a result, Zn//NQNT delivers a high capacity of 235 mAh g⁻¹, a ∼0.8 V discharge plateau, excellent rate capability, and ultrastable cycling over 50 000 cycles. Operando and ex situ spectroscopy reveal a highly reversible six-electron Zn²⁺/H⁺ co-storage mechanism. NQNT also exhibits efficient Al³⁺ storage (212 mAh g⁻¹) and robust performance from −50°C to 50°C. This work establishes a generalizable molecular-design strategy for stable, high-energy organic cathodes compatible with diverse multivalent-ion chemistries.