The synthesis of nanocellulose/B, N, F tri-doped graphene composite hydrogels for supercapacitor applications

Good porous structure and pseudocapacitive active heteroatoms play a key role in boosting the electrochemical characteristics of graphene materials. In this work, nanocellulose/B, N, F tri-doped graphene composite hydrogels (NTGHs) are prepared via an easy hydrothermal process, in which graphene oxide (GO), ammonium fluoroborate and nanocellulose (NC) are utilized as structure regulator, dopant and spacer, respectively. The NTGHs exhibit medium-specific surface area, big packing density, high heteroatomic content, and dense porous structure with good hydrophilicity. As a result, the symmetric aqueous supercapacitor (SASC) based on the optimal sample NTGH-75 display remarkable gravimetric (268.8 F g-1) and volumetric (311.8 F cm-3) specific capacitance, excellent rate capability (81.6 % capacitance retention at 10 A g-1) and long lifespan. In particular, the all-solid-state supercapacitors (ASSC) assembled by NTGH-75 also presents high specific capacitance (177.8 F g-1), favorable impedance characteristics, and good cycle stability. The synthesis strategy in this paper provides new inspiration for the application of graphene-based electrode materials.