摘要
N-type organic cathodes,which are representative high-capacity organic materials,still exhibit low output voltage when paired with zinc anode in aqueous batteries(typically below 0.8 V vs.Zn^(2+)/Zn),thereby limiting their energy densities.In this work,we demonstrate that the strong electron-withdrawing cyano groups in 7,7,8,8-tetracyanoquinodimethane(TCNQ)enable a high output voltage(1.15 V vs.Zn^(2+)/Zn).However,challenges such as sluggish redox kinetics and rapid capacity decay arise during Zn^(2+)ion storage.The incorporation of Na^(+)ions and I^(-)/I_(3)^(-)redox mediator in the conventional ZnSO4 aqueous electrolyte is proposed to address these issues.Comprehensive characterizations reveal that Na^(+)ions preferentially intercalated into TCNQ over Zn^(2+)ions,resulting in a more favorable interlayer spacing adjustment due to their low charge density.Additionally,the iodine redox couple synergistically interacts with the TCNQ redox process,constructing a“cascade”mechanism that chemically oxidizes NaTCNQ,ensuring its complete conversion back to TCNQ.Benefiting from the synergy of Na^(+)and I^(-)ions,the TCNQ cathode demonstrates significant improvement in reversibility,rate capability,and excellent cycle performance of 2000 cycles with a decay rate of 0.0035%per cycle.This work provides a new strategy for optimizing high-performance organic cathodes for aqueous batteries.
基金
supported by the National Natural Science Foundation of China(22479043)
the Major Program of the Natural Science Foundation of Hunan Province(2021JC0006,2025JJ30005)
the Postdoctoral Fellowship Program of China Postdoctoral Science Fund(GZC20230760).
