Tuning electronic structure endows 1,4-naphthoquinones with significantly boosted Zn-ion storage capability and output voltage

Quinone molecular for Zn ion storage typically undergo unsatisfactory capacity and low output voltage because of their poor redox activity of carbonyl group and low redox potential. Here, we demonstrate an energetic strategy to remarkably improve the Zn ion storage capability of 1,4-naphthoquinone by rationally modulating the electronic structure via functional group substitution. The dichloro substituted 1,4-naphthoquinone cathode delivers a high capacity (164.5 mAh g−1 at 0.2 A g−1) and a voltage elevation of 50 mV compared to pristine 1,4-naphthoquinone cathode (12 mAh g−1). Experimental results and density functional theory studies consistently reveal that the introduction of electron-withdrawing Cl substituent can effectively manipulate the electron density of carbonyl carbon and molecular orbital energy levels of 1,4-naphthoquinone, endowing it with higher redox reactivity and discharge plateau. The capability to modulate the electron structure of the quinone cathode by molecular-level designing can provide valuable insights for the development of high-performance zinc battery cathode.