Sustainable alkaline metal ion batteries using organic electrodes are promising for large-scale renewable energy storage. Traditional anode compounds are always anchored with harmful aromatic rings, which results in high toxicity. In this work, a series of aromatics-free organic electrode material based on an azo group is applied in alkaline metal ion batteries. Lithium-, sodium- and potassium-ion batteries based on acyclic compound 2, 2'-azobis(2-methylpropionitrile) (AIBN) as an anode material exhibit low toxicity. In situ Raman and ex situ Fourier-transform infrared spectroscopy results reveal that the azo group serves as the electrochemical active site for the reversible insertion and extraction of alkaline metal ions. Another compound with low toxic, 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA), which containing two active sites of azo and imine groups confirmed with in situ Raman and ex situ FT-IR, are applied in lithium-ion batteries. Furthermore, harmless sodium ion battery has been assembled with azodicarbonamide (CONH). Therefore, this acyclic compound offers possibilities in novel organic electrode materials for developing toxin-free and environmental-friendly alkaline metal ion batteries. (C) 2019 Elsevier Ltd. All rights reserved.