An in-situ engineered azo-linked conjugated polymer anode enabling ultra-stable, high-energy aqueous alkaline batteries at -60 ℃

Abstract

Aqueous alkaline nickel-based batteries are regarded as ideal candidates for large-scale energy storage due to their high safety and inherent low cost, but they are plagued by the toxicity, side reactions and high cost of conventional metal anode materials, such as Cd, Zn, metal hydride alloys. Herein, we report an azo-linked conjugated organic polymer (PBPA) synthesised via in situ electrochemical reduction and coupling of nitro groups on 2,8,14-trinitrohexaazatrinaphthalene (HATN-3NO2) in a high-concentration alkaline electrolyte with low free water activity. This resulting polymer, featuring a high density of active C=N and N=N groups and enhanced electron delocalization, emerges as a promising anode owing to its low cost, excellent cyclability, and low redox potential. When assembled into a PBPA//Ni(OH)2 full cell, it demonstrates remarkable performance, including a high anode-specific capacity of 324.9 mAh g-1, exceptional durability over 30,000 cycles at 10 A g-1, and outstanding low-temperature capabilities (117% capacity retention after 560 cycles at -60 °C), which outperform commercial nickel-hydrogen batteries and most reported aqueous alkaline systems. This potential is further highlighted by the fabrication of a high-mass loading (14.4 mg cm-2) self-supporting electrode, which delivers a high operating voltage of 1.25 V with minimal capacity decay, underscoring the significant promise of this system for practical energy storage applications.