Disordered carbon negative electrode for electrochemical capacitors and high-rate batteries
Disordered carbon negative electrode for electrochemical capacitors and high-rate batteries
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DOI：
10.1016/j.electacta.2006.01.082
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发表时间：
2006-12
影响因子：
6.6
通讯作者：
Nobuhiro Ogihara;Y. Igarashi;A. Kamakura;K. Naoi;Y. Kusachi;K. Utsugi
中科院分区：
文献类型：
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作者：
Nobuhiro Ogihara;Y. Igarashi;A. Kamakura;K. Naoi;Y. Kusachi;K. Utsugi
为了了解无序碳负极在LiPF6/PC基电解质溶液中的高倍率性能和循环性能，通过光谱和电化学分析研究了不同倍率和放电深度（DOD）的电池性能测试。通过充放电测量，发现羰基 (CedgeO) 和锂醇盐 (Cedge-OLi) 之间发生的表面碳边缘氧化还原反应可提供大容量，并且仅在浅 DOD (2.0–0.4V) 下即可实现快速且高循环性。利用无序碳的 CedgeO/Cedge-OLi 的这种轻松且可逆的作用进行有限或浅的充放电循环，适合不对称混合电容器负极的应用。深度 DOD 放电（2.0-0.0V）揭示了一些复杂过程的存在，涉及孔隙或微孔处的锂簇沉积以及石墨烯层处的锂离子嵌入。发现孔隙处的团簇沉积相对较快且可重复。研究发现，石墨烯中的锂离子嵌入以及随后在微孔中的簇沉积速度很慢，并且由于表面上积累了厚且低离子传导性的固体电解质界面（SEI）膜，因此在 100 次循环后会降低循环性能。
In order to understand the properties of high-rate capability and cycleability for a disordered carbon negative electrode in LiPF6/PC based electrolyte solution, the cell performance tests with various rates and depth of discharges (DODs) has been studied by spectroscopic and electrochemical analyses. From the charge–discharge measurements, a surface carbon-edge redox reaction occurring between a carbonyl (CedgeO) and a lithium alkoxide (Cedge–OLi) that delivers a large capacity was found fast and high cycleability at only shallow DOD (2.0–0.4V). The limited or shallow charge–discharge cycling utilizing such facile and reversible action of the CedgeO/Cedge–OLi of the disordered carbon is suited to an application for an negative electrode of asymmetric hybrid capacitors. A deep DOD discharge (2.0–0.0V) revealed the existence of some complex processes involving a lithium cluster deposition at pores or microvoids as well as a lithium ion intercalation at graphene layers. The cluster deposition at pores was found to be relatively fast and reproducible. The lithium ion intercalation at graphenes and the subsequent cluster deposition at microvoids were found to be slow and degrade the cycleability after 100 cycles because of the accumulation of a thick and low-ion-conductive solid electrolyte interface (SEI) film on surface.