Towards wearable electronic devices: A quasi-solid-state aqueous lithium-ion battery with outstanding stability, flexibility, safety and breathability

High-performance energy storage devices are in urgent need due to the fast development of wearable electronics, while the challenge of achieving outstanding flexibility has not been properly addressed yet, let alone the safety, another critical issue determines their practicability. Herein, we report a quasi-solid-state aqueous rechargeable lithium-ion battery (ARLIB) based on carbon cloth substrates and PVA-LiNO₃ gel polymer electrolyte (GPE). Thanks to the protective PPy coating layer on LiV₃O₈ and the use of solid GPE, the as-assembled ARLIB exhibits a good cycling stability of 98.7% and 79.8% capacity retention after 100 and 500 cycles, respectively. It also demonstrates exceptional flexibility to sustain various deformations including bending, squeezing, twisting and folding because of its solid-state design. Moreover, the ARLIB can be tailored into any desired shapes, and even be punched penetrative holes, exhibiting excellent safety. Thus, the creation of numerous tiny through-holes across the whole ARLIB body is testified feasible, and a designed breathability catering to the demand of comfortability in wearable devices is subsequently realized. Obviously, our study offers a promising strategy to construct flexible energy storage device with outstanding stability, flexibility, safety and breathability towards various wearable electronics.