Nanocellulose-Enabled,\nAll-Nanofiber, High-Performance\nSupercapacitor

Abstract

Nanocellulose has\nbeen used as a sustainable nanomaterial for constructing\nadvanced electrochemical energy-storage systems with renewability,\nlightweight, flexibility, high performance, and satisfying safety.\nHere, we demonstrate a high-performance all-nanofiber asymmetric supercapacitor\n(ASC) assembled using a forest-based, nanocellulose-derived hierarchical\nporous carbon (nanocellulose carbon, HPC) anode, a mesoporous nanocellulose\nmembrane separator (nanocellulose separator), and a NiCo₂O₄ cathode with nanocellulose carbon as the support matrix\n(nanocellulose cathode, HPC/NiCo₂O₄). HPC has\na three-dimensional porous structure comprising interconnected nanofibers\nwith an ultrahigh surface area of 2046 m² g^–1. When integrated with the mesoporous feature of the nanocellulose\nmembrane separator, these properties facilitate the quick delivery\nof both ions and electrons even with a thick (up to several hundreds\nof micrometers) and highly loaded (5.8 mg cm^–2)\nASC design. Consequently, the all-nanofiber ASC demonstrates a high\nelectrochemical performance (64.83 F g^–1 (10.84\nF cm^–3) at 0.25 A g^–1 and 32.78\nF g^–1 or 5.48 F cm^–3 at 4 A g^–1) that surpasses most cellulose-based ASCs ever reported.\nMoreover, the nanocellulose components promise renewability, low cost,\nand biodegradability, thereby presenting a promising direction toward\nhigh-power, environmentally friendly, and renewable energy-storage\ndevices.