Xie Yihui, Li Ming, Ma Yijian, Lin Fakun, Zhu Hongbiao, Li Wenbiao, Jiang Shangxu, Shen Chengshuo, Jia Zhongfan, Zhang Kai
School of Chemistry and Chemical Engineering, Zhejiang Sci-Tech University, Hangzhou 310000, P. R. China.
Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University, Sturt Road, Bedford Park, Adelaide, South Australia 5042, Australia.
ACS Appl Mater Interfaces. 2024 Nov 6;16(44):60132-60141. doi: 10.1021/acsami.4c09801. Epub 2024 Oct 23.
Azo compounds (AZO), such as azobenzene, are classic organic electrode materials featuring a redox potential close to Zn/Zn. Recent studies show that azobenzene could work as a cathode in aqueous zinc-ion batteries (AZIBs), providing a voltage output of around 0.7 V. However, the energy storage mechanism of AZO cathodes in AZIBs remains unclear, and their practical usage in AZIBs is hindered by the low voltage. In this study, azopyridine isomers, the hydrophilic analogues of azobenzene, were adopted as cathodes for AZIBs, and the energy storage mechanism was unveiled through aqueous electrochemical studies. Through electrochemical characterizations and theoretical computations, we reveal that both the electron-withdrawing effect of the pyridyl group and the H-involved -N = N-/-NH-NH- redox reaction uplift the redox potential of the azopyridine cathodes. These findings led to the first AZO-based AZIB, providing a voltage output of 1.4 V. The proposed air-stable AZIBs deliver a high energy/power density and a capacity of around 200 mAh g. This work discovers different azopyridine electrochemistry in aqueous and organic electrolytes and enabling AZIBs to outperform its competitors from the AZO family.
偶氮化合物（AZO），如偶氮苯，是典型的有机电极材料，其氧化还原电位接近Zn/Zn²⁺。最近的研究表明，偶氮苯可作为水系锌离子电池（AZIBs）的阴极，提供约0.7 V的电压输出。然而，AZO阴极在AZIBs中的储能机制仍不清楚，并且其在AZIBs中的实际应用受到低电压的阻碍。在本研究中，偶氮吡啶异构体，即偶氮苯的亲水性类似物，被用作AZIBs的阴极，并通过水系电化学研究揭示了其储能机制。通过电化学表征和理论计算，我们发现吡啶基的吸电子效应和涉及氢的-N=N-/-NH-NH-氧化还原反应提高了偶氮吡啶阴极的氧化还原电位。这些发现促成了首个基于AZO的AZIB，其电压输出为1.4 V。所提出的空气稳定型AZIBs具有高能量/功率密度和约200 mAh g⁻¹的容量。这项工作发现了偶氮吡啶在水系和有机电解质中的不同电化学性质，并使AZIBs优于其在AZO家族中的竞争对手。
