Multi‐Responsive Supercapacitors from Chiral Nematic Cellulose Nanocrystal‐Based Activated Carbon Aerogels

Abstract

AbstractThe development of long‐lived electrochemical energy storage systems based on renewable materials is integral for the transition toward a more sustainable society. Supercapacitors have garnered considerable interest given their impressive cycling performance, low cost, and safety. Here, the first example of a chiral nematic activated carbon aerogel is shown. Specifically, supercapacitor materials are developed based on cellulose, a non‐toxic and biodegradable material. The chiral nematic structure of cellulose nanocrystals (CNCs) is harnessed to obtain free‐standing hierarchically ordered activated carbon aerogels. To impart multifunctionality, iron‐ and cobalt‐oxide nanoparticles are incorporated within the CNC matrix. The hierarchical structure remains intact even at nanoparticle concentrations of ≈70 wt%. The aerogels are highly porous, with specific surface areas up to 820 m2 g−1. A maximum magnetization of 17.8 ± 0.1 emu g−1 with superparamagnetic behavior is obtained, providing a base for actuator applications. These materials are employed as symmetric supercapacitors; owing to the concomitant effect of the hierarchically arranged carbon skeleton and KOH activation, a maximum Cp of 294 F g−1 with a capacitance retention of 93% after 2500 cycles at 50 mV s−1 is achieved. The multifunctionality of the composite aerogels opens new possibilities for the use of biomass‐derived materials in energy storage and sensing applications.