Chem. J. Chinese Universities ›› 2023, Vol. 44 ›› Issue (2): 20220497.doi: 10.7503/cjcu20220497

• Physical Chemistry • Previous Articles     Next Articles

Preparation of Hierarchical Porous Carbon Materials Using Cellulose Nanocrystals as Templates and Their Electrochemical Properties

WANG Pengfei, FU Wenhao, SUN Shaoni, CAO Xuefei(), YUAN Tongqi   

  1. Beijing Key Laboratory of Lignocellulosic Chemistry,School of Materials Science and Technology,Beijing Forestry University,Beijing 100083,China
  • Received:2022-07-23 Online:2023-02-10 Published:2022-09-28
  • Contact: CAO Xuefei E-mail:caoxuefei@bjfu.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(32071717)

Abstract:

Cellulose nanocrystals(CNC), phenolic resins, and KOH were used as templates, carbon sources, and activator, respectively, to prepare hierarchically porous carbon materials by high-temperature carbonization. The needle shaped CNC used was 20—40 nm wide and 200—500 nm long, and the carbon residue rate of which at 800 ℃ was only 5.18%(mass fraction). The as prepared carbon materials were characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM), X-ray photoelectron spectra(XPS), etc. The results showed that the degradation of CNC in the precursor could form mesopores comparable to diameter of CNC in carbon materials, and KOH activation could result in a large number of micropores and macropores, as well as some smaller mesopores around 4 nm, leading to a typical hierarchical porous structure of the carbon materials. The presence of these pores is beneficial to shorten the electrolyte diffusion path and change the diffusion process of the electrolyte in the internal cavities of the material. The XPS spectra showed that the surface of the carbon material was rich in oxygen-containing functional groups, which help to improve the wetting ability of the carbon material surface in the electrolyte. The specific surface area and total pore volume of the carbon materials prepared using CNC as template and KOH as activator reached 554.7 m 2/g and 0.323 cm 3/g, respectively. This carbon material was further used as the electrode material, the specific capacitance of which could reach 202.8 F/g at a current density of 1.0 A/g, and the capacitance retention rate still reached 69% when the current density increased from 1.0 A/g to 40.0 A/g, indicating the excellent rate performance of the prepared carbon material. The electrode material was further assembled into a supercapacitor. After 10000 charge and discharge cycles, the capacitance retention rate of the supercapacitor was still over 95%, suggesting its good cycle stability. This study showed that using CNC as template can introduce specific-scale mesopores into carbon materials, thereby improving their electrochemical performance, which provide a new method for the preparation of hierarchically porous carbon materials.

Key words: Carbon material, Mesopore, Template, Cellulose nanocrystals, Supercapacitor

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