Rational design of freestanding and high-performance thick electrode from carbon foam modified with polypyrrole/polydopamine for supercapacitors

The use of thick electrodes via increasing the loading mass of active materials can effectively improve the energy density of supercapacitors at the cell level. However, the loading increase is generally accompanied by the attenuation of charge transport efficiency and the inadequate utilization of active materials, especially for conductive polymers. Herein, we reported a freestanding and thick supercapacitor electrode by a one-step electrochemical deposition of polypyrrole (PPy) and polydopamine (PDA) on the carbon foam with hierarchical pore structures (CFF). The use of PDA effectively limits the dense stacking of PPy, and the macropores in CFF promotes the infiltration of electrolyte inside the electrode. The capacitance of the composite electrode can reach 1920 mF cm−2, as the loading of the PPy/PDA coating is 8.5 mg cm−2. Besides, the assembled symmetric supercapacitor exhibits an outstanding capacitance of 996 mF cm−2 and a high energy density of 0.12 mW h cm−2. Furthermore, 100% capacitance retention can be obtained after 10,000 charging/discharging cycles. This strategy provides a new perspective for the design of high loading composite electrodes based on conductive polymers to obtain preferable electrochemical performances.