高等学校化学学报 ›› 2023, Vol. 44 ›› Issue (2): 20220497.doi: 10.7503/cjcu20220497

• 物理化学 • 上一篇    下一篇

纤维素纳米晶模板法制备多级孔炭材料及其电化学性能

王鹏飞, 富文豪, 孙少妮, 曹学飞(), 袁同琦   

  1. 北京林业大学材料科学与技术学院, 林木生物质化学北京市重点实验室, 北京 100083
  • 收稿日期:2022-07-23 出版日期:2023-02-10 发布日期:2022-09-28
  • 通讯作者: 曹学飞 E-mail:caoxuefei@bjfu.edu.cn
  • 基金资助:
    国家自然科学基金(32071717)

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)

摘要:

以纤维素纳米晶(CNC)为模板, 酚醛树脂为碳源, KOH为活化剂, 通过高温碳化制备了多级孔炭材料. 采用透射电子显微镜(TEM)、 扫描电子显微镜(SEM)和X射线光电子能谱仪(XPS)等手段对合成的一系列炭材料进行了表征. 结果表明, 前驱体中CNC的降解会形成与CNC直径相当的介孔, KOH活化则会导致炭材料产生大量的微孔和大孔, 以及部分4 nm左右较小尺度的介孔, 所制备炭材料呈现明显的多级孔特性, 其比表面积达554.7 m 2/g, 总孔体积为0.323 cm 3/g. 以CNC为模板, KOH活化的炭材料作为电极材料时, 在1.0 A/g电流密度下其比电容达202.8 F/g, 当电流密度升高至40.0 A/g时, 其电容保持率仍达69%, 表明该炭材料具有优异的倍率性能; 由该电极材料组装的超级电容器在10000次充放电循环后, 电容保持率达 95%以上, 具有良好的循环稳定性.

关键词: 炭材料, 介孔, 模板, 纤维素纳米晶, 超级电容器

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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