A zinc ion yarn battery with high capacity and fire retardancy based on a SiO₂ nanoparticle doped ionogel electrolyte

Ionogel electrolytes are proposed to be an excellent substitute for liquid electrolytes due to their superior portability, flexibility and safety without any leakage that may lead to the failure of batteries. Given these natural characteristics, ionogels can provide batteries with good flexibility and wearability. However, the instability under different extreme working conditions and low ionic conductivity limit the further applications of ionogels. In this research, an ionogel electrolyte is synthesized by polymerizing 1-vinyl-3-ethylimidazolium dicyanamide ([Veim][DCA]) and N,N-methylenebisacrylamide (NNMBA) in zinc acetate (Zn(CH3COO)2) and manganese sulfate (MnSO4) dissolved 1-ethyl-3-methylimidazolium dicyanamide ([Emim][DCA]). The fire retardancy of the ionogel electrolyte is improved by adding SiO2 nanoparticles into the electrolyte. The ionogel electrolyte with 40 wt% silicon dioxide (SiO2) nanoparticles possesses a high ionic conductivity of 0.013 S cm-1 and the zinc//manganese dioxide (Zn//MnO2) battery based on the ionogel electrolyte is able to deliver a high specific capacity of 277 mA h g-1 and a high energy density of 283 W h kg-1. Moreover, the SiO2 nanoparticles contained in the ionogel endow the battery with good fire retardancy. Put together, the yarn battery successfully meets the requirements of modern flexible and wearable electronics.