Revealing dual capacitive mechanism of carbon cathode toward ultrafast quasi-solid-state lithium ion capacitors

• 作者: Kangyu Zou Peng Cai Xinglan Deng Baowei Wang Cheng Liu Jiayang Li Hongshuai Hou Guoqiang Zou Xiaobo Ji
• 来源期刊: 能源化学
• 年，卷（期）: 2021,（9）
• 页码范围: 209-221
• 页数: 13页
• 语种: 英文

摘要

High-performance lithium ion capacitors(LICs)have been seriously hindered by the very low capacity and unclear capacitive mechanism of carbon cathode.Herein,after the combination of experimental results and theoretical calculations,it is found that the critical pore size of 0.8 nm for PF6-ion adsorption decreases strong interactive repulsion of electrons and largely reduces adsorption energy barrier,which greatly improves the charge accommodation capacity in electrical double-layer behavior.Most impor-tantly,the chemical-bond evolution process of C=O group has been firstly revealed by X-ray photoelec-tron spectroscopy(XPS),indicating that the introduction of C=O group can provide abundant redox active sites for PF6 ion adsorption accompanied with enhanced pseudocapacitive capacity.Attributed to the synergistic effect of dual capacitive mechanism,porous carbon sheet(PCS)cathode shows a reversible specific capacity of 53.6 mAh g-1 even at a high current density of 50 A g-1.Significantly,the quasi-solid-state LIC manifests state-of-the-art electrochemical performances with an integrated maximum energy density of 163 Wh kg-1 and an outstanding power density of 15,000 W kg-1.This elaborate work promotes better fundamental understanding about capacitive mechanism of PF6-ion and offers a rational dual-capacitive strategy for the design of advanced carbon cathodes.