Chemical Industry and Engineering Progress ›› 2023, Vol. 42 ›› Issue (8): 4340-4350.DOI: 10.16085/j.issn.1000-6613.2022-1791

• Materials science and technology • Previous Articles     Next Articles

Application of coal-based graphene quantum dots in supercapacitors

ZHANG Yaojie(), ZHANG Chuanxiang(), SUN Yue, ZENG Huihui, JIA Jianbo, JIANG Zhendong()   

  1. College of Chemistry and Chemical Engineering, Henan Polytechnic University, Jiaozuo 454003, Henan, China
  • Received:2022-09-23 Revised:2022-11-06 Online:2023-09-19 Published:2023-08-15
  • Contact: ZHANG Chuanxiang, JIANG Zhendong

煤基石墨烯量子点在超级电容器中的应用

张耀杰(), 张传祥(), 孙悦, 曾会会, 贾建波, 蒋振东()   

  1. 河南理工大学化学化工学院,河南 焦作 454003
  • 通讯作者: 张传祥,蒋振东
  • 作者简介:张耀杰(1993—),男,博士研究生,研究方向为煤基先进功能材料。E-mail:1020105281@qq.com
  • 基金资助:
    国家自然科学基金(52074109);河南省高校基本科研业务费专项资金(NSFRF210317)

Abstract:

In order to solve the problems of excessive use of potassium hydroxide (KOH) and unreasonable pore structure distribution in the preparation of coal-based activated carbon, Taxi anthracite was used as carbon source to oxidize graphene quantum dots by potassium ferrate and hydrogen peroxide, and then mixed with KOH to prepare coal-based graphene quantum dots activated carbon. The results showed that this method could reduce the amount of KOH (making the alkali-carbon ratio less than 1), and the activation mechanism of the alkali-carbon ratio to graphene quantum dots was similar to that of coal. When the amount of KOH was small (alkali-carbon ratio with 0.25), only pore-forming effect was observed. After increasing the dosage (alkali-carbon ratio with 0.5), KOH had not only the pore-forming effect, but also the pore-expanding effect. The excess KOH (alkali carbon ratio with 0.75) was mainly focus on pore-expanding effect. With the increase of alkali-carbon ratio, the specific surface area and total pore volume of activated carbon also increased, and the micropore rate gradually decreased, while the mesoporous rate and the average pore size increased. When the alkali-carbon ratio was 0.75, the activation effect was the best. The specific surface area of GQDAC-0.75 was 1207.3m2/g, the micropore rate was 39.5%, and the mesoporous rate was 51.8%. Thanks to its unique hierarchical pore structure of "macropore-mesopore-micropore", GQDAC-0.75 showed the optimal electrochemical performance with specific capacitance of 243.6F/g at 0.5A/g current density. When the current density increased to 10A/g, the specific capacitance of GQDAC-0.75 was maintained at 202.2F/g. Even the current density continued to increase to 100A/g, the specific capacitance was still 179.5F/g, and the specific capacitance could remain 191.6F/g at the current density of 20A/g after 10000 cycles with a 98.1% retention rate, which indicated the excellent rate performance and cycle performance.

Key words: coal, graphene quantum dots, activation, microstructure, activated carbon, supercapacitor

摘要:

针对目前制备煤基活性炭氢氧化钾(KOH)使用比例过高及孔结构分布不合理问题,以太西无烟煤为碳源,先采用高铁酸钾与过氧化氢分步氧化将其氧化为石墨烯量子点,再与KOH混合活化制备煤基石墨烯量子点活性炭。结果表明,这种方法可降低KOH使用量(使碱炭比小于1),且碱炭比对煤基石墨烯量子点的活化机制与对煤的活化机制类似:KOH用量较少时(碱炭比0.25)只有造孔作用;增加用量后(碱炭比0.5),KOH不但有造孔作用,还有扩孔作用;过量的KOH(碱炭比0.75)则以扩孔为主。随着碱炭比的增加,活性炭的比表面积与总孔容也随之增加,微孔率逐渐下降,中孔率和平均孔径都在增长。在碱炭比为0.75时,活化效果最好,GQDAC-0.75比表面积为1207.3m2/g,微孔率为39.5%,中孔率为51.8%;得益于其独特的“大孔-中孔-微孔”的层次孔结构,GQDAC-0.75表现出最优的电化学性能,在0.5A/g电流密度下比电容达243.6F/g,当电流密度增大到10A/g时,GQDAC-0.75的比电容保持在202.2F/g,继续增大电流密度到100A/g,比电容仍有179.5F/g,且在20A/g电流密度下循环10000次后比电容仍有191.6F/g,保持率为98.1%,具有优异的倍率性能和循环稳定性。

关键词: 煤, 石墨烯量子点, 活化, 微观结构, 活性炭, 超级电容器

CLC Number: 

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