Cu superstructures hydrothermally reduced by leaves and derived Cu-Co₃O₄ hybrids for flexible solid-state electrochemical energy storage devices

Cu-Co₃O₄ hybrids and activated carbon were employed to fabricate flexible solid-state electrochemical energy storage devices via facile processing. The resulting flexible devices showed a large specific capacitance of 530 mF cm^-2 with excellent mechanical flexibility, which offered a maximum volumetric energy density of 0.71 mW h cm^-3, and delivered a maximum power density of 88.6 mW cm^-3. What's more, the device showed an excellent cycling stability with only ∼5.2% decay after 6000 cycles.