摘要
碳材料是水系电化学电容器最重要的电极材料之一,但是它的本征非极性表面被极性的水系电解质浸润一直存在挑战。本工作采用聚合物接枝法将具有良好亲水性的聚乙二醇(PEG)分子刷接枝在碳微球的表面,可改善碳微球作为电极材料对水系电解质的浸润性。通过电极材料在6 mol/L KOH电解质中的分散性和静态水接触角测试表明,PEG分子刷改性的碳微球(P-C_(sa))电极材料展现更良好的水系电解质浸润性。循环伏安、恒流充放电法和交流阻抗等电化学测试显示,在电流密度为0.625 A/g时,P-C_(sa)电极材料的比容量比未改性碳微球电极材料提高了60%;该电极材料展现出良好的倍率性能、低的本征阻抗(0.94Ω)和高的循环稳定性(在1.25 A/g电流密度下,10000次循环后保持初始比容量的73.29%)。值得指出的是,PEG分子刷改性碳微球电极材料并未引入法拉第赝电容,主要改善电极材料表面的水系电解质浸润性。
Carbon material is one of the most important electrode materials of electrochemical capacitor;however,it is always a challenge for carbon materials to be wetted by aqueous electrolyte with polarity,due to the intrinsic non-polarity of carbon materials surface.Herein,polyethylene glycol(PEG)molecular brushes with excellent hydrophilicity were grafted on carbon microspheres(C_(sa))surface through polymer grafting to improve the wettability of the C_(sa) as electrode active materials toward aqueous electrolyte.The dispersibility test of electrode materials in 6 mol/L KOH electrolyte and static water contact angels showed that the PEG molecular brushes modified C_(sa)(P-C_(sa))was better to be wetted by aqueous electrolyte than the unmodified C_(sa).Electrochemical tests,such as cyclic voltammograms,galvanostatic charge-discharge,electrochemical impedance spectroscopy,demonstrated that the specific capacity of P-C_(sa) electrode material was nearly 60%higher than that of unmodified C_(sa) electrode material at current density of 0.625 A/g,and the P-C_(sa) electrode material also exhibited excellent rate performance,low intrinsic impedance(0.94Ω)and high cycle stability(73.29%of the initial specific capacity after 10000 cycles at current density of 1.25 A/g).It is worth pointing out that the modification of PEG molecular brushes for C_(sa) electrode material does not introduce faradic pseudocapacitance,which mainly improves the wettability of electrode materials surface toward aqueous electrolyte.
作者
赵磊
彭元佑
李媛
张倩倩
冉奋
ZHAO Lei;PENG Yuanyou;LI Yuan;ZHANG Qianqian;RAN Fen(State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals,School of Material Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China;School of Mechanical Engineering,Longdong University,Qingyang 745000,Gansu,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2022年第21期31-37,共7页
Materials Reports
基金
国家自然科学基金(51763014,52073133)
兰州理工大学红柳杰出青年学者项目
甘肃省青年科技基金计划(20JR10RA137)。
关键词
碳微球
分子刷
聚乙二醇
聚合物接枝
电极材料
carbon microspheres
molecular brush
polyethylene glycol
polymer grafting
electrode material
