The increasing interests in flexible and wearable electronics stimulates the exploration of new energy storage systems. Flexible aluminum-air batteries with the features of high energy density, good safety, low cost and eco-friendly have attracted much attention. Herein, a sodium polyacrylate (PANa) based electrolyte with an optimized amount of sodium carboxymethyl cellulose (CMC) is prepared through free radical polymerization and employed to fabricate flexible Al-air batteries. The prepared PANa-5% CMC polymer electrolyte exhibits excellent ionic conductivity (0.324 S cm −1 ), mechanical strength and water uptake ability. This achieved properties can be attributed to the introduce of CMC, which not only decreases size of the pores but also forms the cobweb-like networks with a large amount of functional groups. The fabricated Al-air battery displays good flexibility and shows enhanced discharge performance with a higher voltage plateau and larger specific capacity, resulting in a maximum power density of 137 mW cm −2 . More importantly, the used gel polymer electrolyte can be recovered without any performance decay. Furthermore, the Al-air batteries are demonstrated to charge mobile phone and power smart watch in a flexible state, showing promising potential in flexible energy storage devices.

3,6-diphenyltetrazine (DPT) is an electron-deficient π-conjugated molecule with a perfectly planar structure and high crystallinity. In this study, discharge-charge tests of crystalline DPT as a cathode material for sodium ion batteries were conducted. DPT showed an initial reversible capacity of 102 mAh/g (theoretical capacity 114 mAh/g), corresponding to one electron reaction. The plateau of the discharge-charge profiles was observed at 1.9-2.1 V vs. Na/Na + . According to the ex-situ XRD, FT-IR, and XPS measurements to investigate the discharge-charge mechanism, the redox center was identified as the conjugated tetrazine ring. DPT was in a crystalline form in both the charged and discharged state and indicated the potential as a reversible Na ion host.