A facile approach to nanoarchitectured three-dimensional graphene-based Li-Mn-O composite as high-power cathodes for Li-ion batteries

Abstract

We report a facile method to prepare a nanoarchitectured lithium manganate/graphene (LMO/G) hybrid as a positive electrode for Li-ion batteries. The Mn O /graphene hybrid is synthesized by exfoliation of graphene sheets and deposition of Mn O in a onestep electrochemical process, which is followed by lithiation in a molten salt reaction. There are several advantages of using the LMO/G as cathodes in Li-ion batteries: (1) the LMO/G electrode shows high specific capacities at high gravimetric current densities with excellent cycling stability, e.g., 84 mAh·g during the 500th cycle at a discharge current density of 5625 mA·g (~38.01 C capacity rating) in the voltage window of 3-4.5 V; (2) the LMO/G hybrid can buffer the Jahn-Teller effect, which depicts excellent Li storage properties at high current densities within a wider voltage window of 2-4.5 V, e.g., 93 mAh·g during the 300th cycle at a discharge current density of 5625 mA·g (~38.01 C). The wider operation voltage window can lead to increased theoretical capacity, e.g., 148 mAh·g-1 between 3 and 4.5 V and 296 mAh·g between 2 and 4.5 V; (3) more importantly, it is found that the attachment of LMO onto graphene can help to reduce the dissolution of Mn into the electrolyte, as indicated by the inductively coupled plasma (ICP) measurements, and which is mainly attributed to the large specific surface area of the graphene sheets. © 2012 Zhang et al. 2 3 2 3 -1 -1 -1 -1 -1 2+