A Honeycomb-like Ammonium-Ion Fiber Battery with High and Stable Performance for Wearable Energy Storage.

Aqueous ammonium-ion batteries have attracted intense interest lately as promising energy storage systems due to the price advantage and fast charge/discharge capability of ammonium-ion redox reactions. However, the research on the strength and energy storage characteristics of ammonium-ion fiber batteries is still limited. In this study, an ammonium-ion fiber battery with excellent mechanical strength, flexibility, high specific capacity, and long cycle-life has been developed with a robust honeycomb-like ammonium vanadate@carbon nanotube (NH 4 V 4 O 10 @CNT) cathode. The fiber electrode delivers a steady specific capacity of 241.06 mAh cm -3 at a current of 0.2 mA. Moreover, a fiber full cell consisting of an NH 4 V 4 O 10 @CNT cathode and a PANI@CNT anode exhibits a specific capacity of 7.27 mAh cm -3 at a current of 0.3 mA and retains a high capacity retention of 72.1% after 1000 cycles. Meanwhile, it shows good flexibility and superior electrochemical performance after 500 times bending or at different deformation states. This work offers a reference for long-cycle, flexible fibrous ammonium-ion batteries.