Redox mediator-enhanced hierarchical porous nitrogen-doped ZIF-L derived carbon for wearable supercapacitors

Flexible supercapacitors operating under mild conditions are undoubtedly ideal wearable energy storage devices. However, most electrode active materials exhibit low specific capacitance under mild conditions due to their poor redox activity therein and mass transfer barriers in dominantly microporous structure. Herein, using bovine serum albumin (BSA) as the soft template, a redox mediator-enhanced hierarchical porous N-doped ZIF-L derived carbon (PD/CGB₁@ZIF-L) is synthesized by modifying 1,10-phenanthroline-5,6-dione (PD) on the derived carbon formed after confined carbonization. Benefiting from the N-doping and porous structure as well as the pseudocapacitive enhancement of PD, the prepared composite material has a high specific capacitance of 729.3 mF cm⁻² at a current density of 1 mA cm⁻²(182.3 F g⁻¹ at 0.25 A g⁻¹) in a phosphate buffer solution (pH = 7). The flexible device constructed based on PD/CGB₁@ZIF-L has high flexibility and mechanical stability, with a high specific capacitance of 149.1 mF cm⁻²(37.3 F g⁻¹) and a high energy density of 40.6 μWh·cm⁻² at a power density of 0.7 mW cm⁻²(10.2 Wh·kg⁻¹ at 175 W kg⁻¹), and exhibits excellent stability after 10000 cycles. This work provides new ideas for constructing the design of high-performance energy storage devices under mild conditions and broadens the horizon of flexible wearable devices.