碘化钾调控孔结构的石墨烯及其电化学电容器应用  

Graphene with the KI-modified pore structure and its electrochemical capacitor application

作　　者：罗明宇 徐若谷 石颖[1,2] 王宇作 李峰 LUO Ming-yu;XU Ruo-gu;SHI Ying;WANG Yu-zuo;LI Feng(Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China;Institute of Advanced Energy Storage Technology and Equipment,Ningbo University,Ningbo 315211,China)

机构地区：[1]中国科学院金属研究所,沈阳材料科学国家研究中心,辽宁沈阳110016 [2]中国科学技术大学材料科学与工程学院,辽宁沈阳110016 [3]宁波大学先进储能技术与装备研究院,浙江宁波315211

出　　处：《新型炭材料（中英文）》2023年第2期317-326,共10页New Carbon Materials

基　　金：感谢国家自然科学基金(No.22078164)。

摘　　要：较低的体积能量密度限制了当前电化学电容器的应用,而提高体积能量密度的关键在于发展具有致密化储能特性的多孔炭材料。目前,毛细致密化已成为平衡多孔炭密度和孔隙率从而提高材料体积比电容的主要方法,但仍在孔结构的精细调控方面存在不足,制约了毛细致密化多孔炭与高电压离子液体的兼容性。本文提出了碘化钾(KI)辅助的毛细致密化策略,通过在石墨烯网络中预载KI来控制毛细致密化过程,实现了对孔结构的有效调控。同时电化学性能表征结果表明KI具有增加离子到达表面积和提供赝电容的作用。基于此,所制碘化钾/石墨烯材料的密度达到0.96 g cm^(-3),在离子液体中的体积比电容为115Fcm^(-3)。由该材料所组装的电化学电容器可以提供19.6WhL^(-1)的体积能量密度。The use of electrochemical capacitors is greatly limited by their poor volumetric energy density,and the key for improving it is to develop porous yet compact carbon materials.In recent years,the densification of porous carbons by capillary forces during drying has been used as a main method to balance the density and porosity of porous carbons for high volumetric performance.But there are still deficiencies in fine tuning the pore structure,which limits the compatibility of porous carbons with high-voltage ionic liquids.We report a KI-assisted method to prepare graphene-based porous carbons with high density and high capacitance.During the synthesis of the carbons,graphene oxide was dispersed in KI solutions with concentrations of 12.5-37.5 mmol/mL followed by hydrothermal treatment at 180℃ for 6 h.The obtained hydrogels were dried in 0.01 MPa of air at 60℃ for 72 h.By this procedure,KI was loaded into a matrix of compact graphene and formed crystals to suppress over shrinkage of pores during drying to produce densification and pseudo-capacitance.Electrochemical characterization of the resulting materials indicated that the ion-accessible surface area and pseudo-capacitance of the porous carbons were increased.The KI/graphene composite with an optimum concentration of KI of 25 mmol/mL achieved both a high electrode density of 0.96 g cm^(−3) and a high volumetric capacitance of 115 F cm^(−3)(at 1 Ag^(−1))in an ionic liquid electrolyte(1-alkyl-3-methylimidazolium tetrafluoroborate).A symmetric cell assembled using this material had a high volumetric energy density of 19.6 Wh L^(−1).

关 键 词：碘化钾 毛细致密 电化学电容器 体积能量密度 

分 类 号：TQ127.11[化学工程—无机化工]