Porously Assembled 2D Nanosheets of Alkali Metal Manganese Oxides with Highly Reversible Pseudocapacitance Behaviors

详细信息    查看全文

• 作者：Min-Sun Song ; Kyung Min Lee ; Yu Ri Lee ; In Young Kim ; Tae Woo Kim ; Jayavant Laxman Gunjakar ; Seong-Ju Hwang
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：December 23, 2010
• 年：2010
• 卷：114
• 期：50
• 页码：22134-22140
• 全文大小：333K
• 年卷期：v.114,no.50(December 23, 2010)
• ISSN：1932-7455

文摘

Porously assembled 2D nanosheets of alkali metal manganese oxides were synthesized via the flocculation of exfoliated MnO₂ nanosheets with alkali metal cations. According to X-ray diffraction and electron microscopic analyses, the MnO₂ nanosheets were porously restacked with alkali metal cations, resulting in the mesoporous assembly of lamellar crystallites with surface expansion (50−70 m² g⁻¹). Mn K-edge X-ray absorption spectroscopy clearly demonstrated that manganese ions in the reassembled materials were stabilized in octahedral symmetry with the mixed oxidation state of Mn³⁺/Mn⁴⁺. The present reassembled manganates showed large capacitances of 140−160 F g⁻¹ and excellent cyclability of 93−99% up to the 1000th cycle. The electrochemical cycling did not induce notable frustration in the crystal structure of manganate nanosheets, underscoring the high structural stability of the reassembled manganates. This study provided strong evidence for the effectiveness of the exfoliation−reassembling method in enhancing the capacitance performance of layered metal oxides.