曲面(拓扑)
纳米技术
光电子学
表面电荷
电化学储能
电荷(物理)
工程物理
电解质
作者
Chao Wang,Yanxiao Ning,Haibo Huang,Shiwen Li,Chuanhai Xiao,Qi Chen,Li Peng,Shuainan Guo,Yifan Li,Conghui Liu,Zhong-Shuai Wu,Xianfeng Li,Liwei Chen,Chao Gao,Chuan Wu,Qiang Fu
摘要
Surface and interface play critical roles in energy storage devices, calling for operando characterization techniques to probe the electrified surfaces/interfaces. In this work, surface science methodology, including electron spectroscopy and scanning probe microscopy, has been successfully applied to visualize electrochemical processes at operating electrode surfaces in an Al/graphite model battery. Intercalation of anions together with cations is directly observed in the surface region of a graphite electrode with tens of nanometers thickness, the concentration of which is one order higher than that in bulk. An intercalation pseudocapacitance mechanism and a double specific capacity in the electrode surface region are expected based on the super-dense intercalants and anion/cation co-intercalation, which are in sharp contrast to the battery-like mechanism in the electrode bulk. The distinct electrochemical mechanism at the electrode surface is verified by performance tests of real battery devices, showing that a surface-dominant, nanometer-thick graphite cathode outperforms a bulk-dominant, micrometer-thick graphite cathode. Our findings highlight the important surface effect of working electrodes in charge storage systems.
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