Scalable Quasi-Solid-State Supercapacitor for Wide-Temperature Wearable Devices

Quasi-solid-state supercapacitors have wide application prospects in flexible and scalable electronics, which require high capacity, simple form factor, and excellent mechanical robustness. However, it is a challenge to have all these benefits in one material. Addressing this, we report a composite hydrogel with excellent mechanical durability and freezing resistance. The designed composite hydrogel acts both as a load-bearing layer to maintain its structure during deformation and as a permeable binder to stimulate the interfacing between the conductive electrode and the electrolyte to reduce the interface resistance. Flexible supercapacitors are assembled with composite hydrogels and high-performance MnO2/carbon cloth, which has excellent performance and can store energy at different temperatures or bending states. These results show that the tough hydrogel facilitates the improvement of electrical and mechanical stability, showing great potential in wide-temperature wearable devices.