Aqueous zinc-ion batteries (AZIBs) are regarded as highly promising candidates for large-scale energy storage applications, benefiting from their intrinsic safety and high-energy density. Despite the structural tunability and rapid charge–discharge kinetics of organic electrode materials, the realization of excellent rate capability, high capacity, and long-term cycling stability is still a major challenge. Hexaazatrinaphthylene (HATN) and its derivatives feature an electron-deficient, rigid conjugated framework rich in imine groups and have thus attracted extensive research attention. Herein, the π-conjugated HATN-based azo polymer (PAHATN) was constructed from HATN units and azo (−N═N−) linkages for AZIBs. The azo linkages not only facilitate the construction of an extended π-conjugated framework, but also offer abundant active sites and effectively reduce the lowest unoccupied molecular orbital (LUMO) level. The control polymer (PNHATN) consists of HATN units connected through single bonds. The PAHATN cathode exhibited significantly improved specific capacity and cycling stability compared to PNHATN cathode, achieving a maximum discharge voltage of 1.2 V. In addition, the extended π-conjugated framework of PAHATN narrowed the bandgap, strengthened π–π interactions, and significantly enhanced intrinsic conductivity. These synergistic structural features of PAHATN collectively facilitated rapid charge transfer kinetics and outstanding cycling stability. A high reversible capacity of 297 mA h g–1 was achieved at 0.2 A g–1, while 198.9 mA h g–1 was retained at 10 A g–1 (approximately eight times that of the PNHATN cathode), along with 94.7% capacity retention after 30,000 cycles.
Guan et al. (Thu,) studied this question.