Engineering integrated structure for high-performance flexible zinc-ion batteries

The booming wearable electronics stimulate the development of power source toward high flexibility and energy density. Until now, all-in-one integrated batteries are designed to insure the reliable mechanical stability, but the rare attention has been paid to further enhance the energy density of integrated batteries. Herein, a coaxial-like integrated structure design is proposed and demonstrated for flexible aqueous zinc-ion batteries (ZIBs). The freestanding and anti-freezing hydrogel electrolyte is synthesized as a matrix and host for capsulizing core anode and subsequent embedding of outer polymer cathode. The integrated configuration avoids the dislocation of battery components, ensuring the mechanical and electrochemical integrity under frequent deformations. More importantly, the coaxial-like architecture together with porous hydrogel framework could provide a high mass loading for active polymer, thus enhancing the overall capacity and energy density for integrated ZIBs. As a result, the coaxial-like integrated flexible ZIB delivers the high capacity retention of 97.75% after 3000 flexure cycles, low temperature operation at −20 °C, areal capacity of 1.24 mAh cm−2 and energy density of 1.31 mWh cm−2 that far exceed reported counterparts. Furthermore, the high-performance fiber-shaped flexible ZIB is obtained from this coaxial-like integrated design strategy.