Abstract
Mn3O4 aerogels and their graphene nanosheet (GN) composite aerogels were synthesized by a simple supercritical-ethanol process. In the process, supercritical ethanol acted as a reductant to reduce graphene oxide and MnO2 gels simultaneously. The synthesized aerogels consisted of 10–20 nm Mn3O4 nanocrystallites, with BET-specific surface areas around 60 m2/g. The performance of the aerogels as anode materials for lithium-ion batteries was also evaluated in this study. The results showed that Mn3O4 aerogels as anode materials exhibited a reversible capacity of 498.7 mAh/g after 60 charge/discharge cycles while the reversible capacity for Mn3O4/GN composite aerogels could further increase to 665 mAh/g. The mechanisms for the enhanced capacity retention could be attributed to their porous structures and improved electronic contact with GN addition. The process should also offer an effective and facile method to fabricate many other porous metal oxide/GN nanocomposites for low-cost, high-capacity, environmentally benign material for lithium-ion batteries.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-0960-x) contains supplementary material, which is available to authorized users.
Highlights
Nanostructured materials such as nanowires, nanotubes, nanosheets, and porous nanomaterials have attracted great interest in the recent years because of the novel properties from their reduced dimensionality
The results indicate that the supercritical-ethanol process can serve as a drying method to obtain the porous structure of aerogels and reduce high-valence manganese oxide and graphene oxide (GO) simultaneously
Supercritical ethanol under high temperature and high pressure was expected to have improved reducibility to reduce GO pre-mixed in MnO2 gels into graphene nanosheet (GN)
Summary
Nanostructured materials such as nanowires, nanotubes, nanosheets, and porous nanomaterials have attracted great interest in the recent years because of the novel properties from their reduced dimensionality. They are becoming increasingly important for electrochemical energy-storage applications, especially for lithium-ion batteries [1,2,3,4,5]. Aerogels are well-known nanostructured materials with very high surface areas. They have a threedimensional network of nanosized particles surrounded by macro-, meso-, and micropores. The diffusion distances for lithium ions and electrons in the nanosized aerogel particles are expected to be shorter compared with that of the solid electrode materials.
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