Tailoring the Structure of Chitosan-Based Porous Carbon Nanofiber Architectures toward Efficient Capacitive Charge Storage and Capacitive Deionization

László Szabó; Xingtao Xu; Koichiro Uto; Joel Henzie; Yusuke Yamauchi; Izumi Ichinose; Mitsuhiro Ebara

doi:10.1021/acsami.1c20199

Tailoring the Structure of Chitosan-Based Porous Carbon Nanofiber Architectures toward Efficient Capacitive Charge Storage and Capacitive Deionization

ACS Appl Mater Interfaces. 2022 Jan 26;14(3):4004-4021. doi: 10.1021/acsami.1c20199. Epub 2022 Jan 14.

Authors

László Szabó¹, Xingtao Xu², Koichiro Uto³, Joel Henzie², Yusuke Yamauchi^{2

4}, Izumi Ichinose³, Mitsuhiro Ebara³

Affiliations

¹ International Center for Young Scientists, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
² JST-ERATO Yamauchi Materials Space-Tectonics Project, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
³ Research Center for Functional Materials, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
⁴ School of Chemical Engineering and Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, Queensland 4072, Australia.

PMID: 35029967
DOI: 10.1021/acsami.1c20199

Abstract

Carbon nanoarchitectures derived from biobased building blocks are potential sustainable alternatives to electrode materials generated with petroleum-derived resources. We aim at developing a fundamental understanding on the connection between the structure and electrochemical performance of porous carbon nanofiber (PCNF) architectures from the polysaccharide chitosan as a biobased building block. We fabricated a range of PCNF architectures from the chitosan carbon precursor and tailored their structure by varying the amount and molecular weight of the sacrificial pore-forming polymer poly(ethylene oxide). The morphology (high-resolution scanning electron microscopy), carbon structure (X-ray diffraction, transmission electron microscopy), pore network (N₂ gas adsorption, small-angle X-ray scattering), and surface/bulk composition (X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy) were studied in detail together with a comprehensive electrochemical analysis on the fabricated electrodes. In supercapacitor devices, the best-performing freestanding electrode had (1) a high accessible surface area (a_s,BET ≈ 700 m² g^-1) and hierarchical pore network (micro- and mesopores) providing a fast ion diffusion process, high specific capacitance, and rate capability, (2) surface chemistry allowing a high Coulombic efficiency by avoiding parasitic Faradaic side reactions, and (3) a unique turbostratic carbon nanostructure leading to low charge transfer resistance while keeping good electrical conductivity. This electrode exhibited good stability over 2000 cycles (at 2 A g^-1) with high capacitance retention (>80%) and charge efficiency (>90%). In the capacitive deionization (CDI) device, our electrode demonstrated an ultrahigh salt adsorption capacity of 23.6 mg g^-1, which is among the state-of-the-art values reported for a biobased carbon. A high charge efficiency (85%) was achieved during the CDI process using low-cost materials, in contrast to similarly performing devices fabricated with expensive ion exchange membranes or petroleum-based carbon precursors. Our results demonstrate that inexpensive chitosan-based materials can be readily transformed in one carbonization step without any aggressive activating chemicals into tailor-made hierarchically ordered state-of-the-art carbon materials for charge storage devices.

Keywords: capacitive deionization; carbon nanofiber; chitosan; porous carbon; supercapacitor.