Composition‐Tailored 2 D Mn_1−xRu_xO₂ Nanosheets and Their Reassembled Nanocomposites: Improvement of Electrode Performance upon Ru Substitution

Abstract

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.

Two‐Dimensional Metal Oxide and Metal Hydroxide Nanosheets: Synthesis, Controlled Assembly and Applications in Energy Conversion and Storage

“…[63b,c] The capacitance increases to 330–360 F g –1 upon introduction of Ru into the Li‐layered MnO 2 structure, i.e., Mn 1– x Ru x O 2 ( x = 0.05–0.10). The enhancement is attributed to the improvement of nanosheet conductivity upon introduction of Ru …”

2020 Roadmap on two-dimensional nanomaterials for environmental catalysis

“…While hybridization of oxide nanosheets and more conductive second phases as a route to getting materials with improved electrical conductivity has been studied in some depth, the use of controlled defect engineering strategies, e.g., aliovalent doping in 2D oxide lattices, as a tool to improve the lateral conductivity of nanosheets as well as their surface redox properties, and consequently also their performance, has been explored much less [46]. A systematic understanding of the influence of transition metal ion doping into 2D nanosheets on their conductivity, electron transfer (redox) properties and capacity to electrochemically store Li + , will help to boost the performance of nanosheetbased electrodes in batteries and supercapacitors.…”

Synthesis Strategies about 2D Materials

“…This is because these ionic solids have strong ionic bonds in the layers. Ion-change exfoliation is a normal method to get this kind of 2D materials [19][20][21][22][23]. The scheme of ion-change exfoliation is shown in Figure 4a [19].…”