Kim Su-Jeong, Kim In Young, Patil Sharad B, Oh Seung Mi, Lee Nam-Suk, Hwang Seong-Ju
Center for Intelligent Nano-Bio Materials (CINBM), Department of Chemistry and Nano Sciences, College of Natural Sciences, Ewha Womans University, Seoul 120-750 (Korea), Fax: (+82) 2-3277-3419.
Chemistry. 2014 Apr 22;20(17):5132-40. doi: 10.1002/chem.201304009. Epub 2014 Mar 11.
Composition-tailored Mn1-x Rux O2 2 D nanosheets and their reassembled nanocomposites with mesoporous stacking structure are synthesized by a soft-chemical exfoliation reaction and the subsequent reassembling of the exfoliated nanosheets with Li(+) cations, respectively. The tailoring of the chemical compositions of the exfoliated Mn1-x Rux O2 2 D nanosheets and their lithiated nanocomposites can be achieved by adopting the Ru-substituted layered manganese oxides as host materials for exfoliation reaction. Upon the exfoliation-reassembling process, the substituted ruthenium ions remain stabilized in the layered Mn1-x Rux O2 lattice with mixed Ru(3+) /Ru(4+) oxidation state. The reassembled Li-Mn1-x Rux O2 nanocomposites show promising pseudocapacitance performance with large specific capacitances of approximately 330 F g(-1) for the second cycle and approximately 360 F g(-1) for the 500th cycle and excellent cyclability, which are superior to those of the unsubstituted Li-MnO2 homologue and many other MnO2 -based materials. Electrochemical impedance spectroscopy analysis provides strong evidence for the enhancement of the electrical conductivity of 2 D nanostructured manganese oxide upon Ru substitution, which is mainly responsible for the excellent electrode performance of Li-Mn1-x Rux O2 nanocomposites. The results underscore the powerful role of the composition-controllable metal oxide 2 D nanosheets as building blocks for exploring efficient electrode materials.
通过软化学剥离反应以及随后将剥离的纳米片与Li⁺阳离子重新组装，分别合成了成分定制的Mn₁₋ₓRuₓO₂二维纳米片及其具有介孔堆叠结构的重新组装纳米复合材料。通过采用Ru取代的层状锰氧化物作为剥离反应的主体材料，可以实现对剥离的Mn₁₋ₓRuₓO₂二维纳米片及其锂化纳米复合材料化学成分的定制。在剥离-重新组装过程中，取代的钌离子以Ru(³⁺)/Ru(⁴⁺)混合氧化态稳定地保留在层状Mn₁₋ₓRuₓO₂晶格中。重新组装的Li-Mn₁₋ₓRuₓO₂纳米复合材料表现出有前景的赝电容性能，第二循环的比电容约为330 F g⁻¹，第500循环的比电容约为360 F g⁻¹，并且具有优异的循环稳定性，优于未取代的Li-MnO₂同系物和许多其他MnO₂基材料。电化学阻抗谱分析提供了有力证据，表明Ru取代后二维纳米结构锰氧化物的电导率增强，这主要是Li-Mn₁₋ₓRuₓO₂纳米复合材料优异电极性能的原因。结果强调了成分可控的金属氧化物二维纳米片作为探索高效电极材料的构建单元的强大作用。
