Designing p‐π Conjugated Naphthoquinone‐Derivatives as High‐Performance Cathodes for Aqueous Proton Batteries

Abstract 1,4‐naphthoquinone (NQ) is anticipated to emerge as a promising electrode material for designing high‐performance aqueous proton batteries (APBs), attributed to its high theoretical capacity and flexible designability. However, its high solubility and sluggish kinetics are not conducive to long‐term cycling stability and high‐rate capability. Herein, a unique molecular structure design strategy is proposed to construct effective p‐π conjugated structures by inducing the p‐electrons in substituent groups and 𝜋‐electrons on naphthalene rings. Theoretical calculations and experimental results indicate that the p‐π conjugation effect of 2,3‐dichloro‐1,4‐naphthoquinone (2Cl‐NQ) and 1‐hydroxy‐1,4‐naphthoquinone (1OH‐NQ) greatly reduces molecular polarity and expands the π‐conjugate system, which endows them with minimal solubility and superior structural stability, thereby achieving excellent cycling stability with 99.53% and 98.62% capacity retention after 1800 cycles, respectively. Moreover, the p‐π conjugated structures induce a narrowed bandgap, improving electronic conductivity and redox kinetics, thereby significantly enhancing their rate capability. When coupling with perylene‐3,4,9,10‐tetracarboxylic dianhydride (PTCDA) anode, the full battery of 2Cl‐NQ//PTCDA exhibits a high specific capacity of 173 mAh g −1 at 15 A g −1 , maintaining 73.2% capacity retention after 40 000 cycles and demonstrating exceptional cycling performance even at −20 °C. This work provides valuable insights and guidance for designing high‐performance energy storage materials for APBs.