Anomalous Pseudocapacitive Behavior of a Nanostructured, Mixed-Valent Manganese Oxide Film for Electrical Energy Storage
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- 作者：Min-Kyu Song ; Shuang Cheng ; Haiyan Chen ; Wentao Qin ; Kyung-Wan Nam ; Shucheng Xu ; Xiao-Qing Yang ; Angelo Bongiorno ; Jangsoo Lee ; Jianming Bai ; Trevor A. Tyson ; Jaephil Cho ; Meilin Liu
- 刊名：Nano Letters
- 出版年：2012
- 出版时间：July 11, 2012
- 年：2012
- 卷：12
- 期：7
- 页码：3483-3490
- 全文大小：501K
- 年卷期：v.12,no.7(July 11, 2012)
- ISSN：1530-6992
文摘
While pseudocapacitors represent a promising option for electrical energy storage, the performance of the existing ones must be dramatically enhanced to meet today鈥檚 ever-increasing demands for many emerging applications. Here we report a nanostructured, mixed-valent manganese oxide film that exhibits anomalously high specific capacitance (2530 F/g of manganese oxide, measured at 0.61 A/g in a two-electrode configuration with loading of active materials 0.16 mg/cm2) while maintaining excellent power density and cycling life. The dramatic performance enhancement is attributed to its unique mixed-valence state with porous nanoarchitecture, which may facilitate rapid mass transport and enhance surface double-layer capacitance, while promoting facile redox reactions associated with charge storage by both Mn and O sites, as suggested by in situ X-ray absorption spectroscopy (XAS) and density functional theory calculations. The new charge storage mechanisms (in addition to redox reactions of cations) may offer critical insights to rational design of a new-generation energy storage devices.