Polydopamine Doping and Pyrolysis of Cellulose Nanofiber Paper for Fabrication of Three-Dimensional Nanocarbon with Improved Yield and Capacitive Performances

Electrochemical Performance of Symmetric Solid-State Supercapacitors Based on Carbon Xerogel Electrodes and Solid Polymer Electrolytes

For the development and optimization of solid-state symmetrical supercapacitors, herein, we propose using carbon-based electrodes and sodium- and lithium-form Aquivion electrolyte membranes, which serve as the separator and electrolyte. Carbon xerogels, synthesized using microwave-assisted sol-gel methodology, with designed and controlled properties were obtained as electrode materials. Commercial activated carbon (YP-50F, "Kuraray Europe" GmbH) was used as the active material for comparison. Notably, the developed solid-state symmetrical supercapacitors provide sufficiently high specific capacitances of 105-110 F g-1 at 0.2 A g-1, along with an energy density of 4.5 Wh kg-1 at 300 W kg-1, and a voltage window of 0-1.2 V in aqueous environments, also demonstrating an excellent cycling stability for up to 10,000 charge/discharge cycles. These results can demonstrate the potential applications of carbon xerogel as the active electrode material and cation exchange membrane as the electrolyte in the development of solid-state supercapacitor devices.

Design of a Cellulose-Based Supercapacitor Based on Polymerization-Doping Phase Inversion of a Polydopamine-Modified Separator and a Polypyrrole/Graphene-Doped Membrane Electrode

The cellulose-based polydopamine modified separator (LID-PDA) and polydopamine/graphene/polypyrrole modified electrode (LID-PDA-GR/PPy) were successfully fabricated by dissolving-regenerating and phase-inversion methods via dopamine polymerization and doping modification of graphene (GR) and polypyrrole (PPy) in a lithium chloride/N,N-dimethylacetamide solvent system. The structure and physical properties of the LID-PDA film material play a positive role in its application in supercapacitor separators and electrodes. The effect of PPy content on the electrochemical performance of the electrode shows that the LID-PDA-GR/PPy-30 electrode has the best performance (2.2 Ω, 237.2 F/g at 0.5 A/g). The cellulose-based supercapacitor assembled from the LID-PDA-GR/PPy-30 electrode and LID-PDA separator shows good electrochemical energy storage properties (439.0 F/g at 0.2 A/g, 36.2 Wh/kg corresponding to 2.2 kW/kg). Based on the microstructural properties of natural and renewable cellulose substrates, combining polymerization and doping to realize the complementarity between materials is meaningful for the application and development of energy storage materials.