Initiating a wide-temperature-window yarn zinc ion battery by a highly conductive iongel

Yarn batteries are promising candidates in portable, flexible and wearable electronics due to its tiny volume, good flexibility and maximum compatibility with textile. However, the-state-of-the-art yarn battery using aqueous electrolyte cannot fulfill the requirement of working normally in extreme weather conditions, such as harsh winters and searing summers. In this research, a quasi-solid-state iongel electrolyte with a high ionic conductivity of 0.016 S cm−1 was synthesized by polymerizing 1-vinyl-3-ethylimidazolium dicyanamide ([Veim][DCA]) and N, N′-methylenebisacrylamide (NNMBA) in zinc acetate (Zn(CH3COO)2) dissolved 1-ethyl-3-methylimidazolium dicyanamide ([Emim][DCA]). A flexible zinc//manganese-dioxide (Zn//MnO2) yarn battery based on this iongel delivers high volumetric capacity of 2.4 mAh cm−3 and length/areal/volumetric energy density of 0.0075 mWh cm−1/0.03 mWh cm−2/2.0 mWh cm−3 at 0 °C, all of which are higher than values of many previously reported devices at room temperature so far. Moreover, compared with these at 0 °C, the volumetric capacity and length/areal/volumetric energy density of the battery get 1.4- and 1.4-fold enhancement when temperature rises to 25 °C, and 1.9- and 2.1-fold enhancement at 60 °C, respectively. This research indicates that our yarn battery is suitable for harsh winters and searing summers, laying a solid foundation for the universal application of wearable electronics.