In situ measurement and mechanism analysis of the lithium storage behavior of graphene electrodes

Abstract

Graphene has attracted widespread attention for development of high-performance lithium-ion battery anode materials. In this paper, the lithium storage mechanisms of multilayer graphene, few-layer graphene, and reduced graphene oxide electrodes are investigated, and the influences of layers and defects in the microstructure are analyzed. The evolution of microstructure deformation of different graphene electrodes, combined with the diffusivity and distribution of lithium, is systemically investigated by in-situ Raman spectroscopy during lithiation and delithiation. The results show that graphene electrodes with different structures exhibit different mechanical behaviors and thus different lithium storage capacities. Mechanical analysis indicates that although the surfaces and defects are active, interlayer lithium insertion contributes the most lithium storage capacity. As the number of graphene layers increases and/or defects decrease, more interlayer spaces would be provided. Thus, the lithium storage capacity of multilayer graphene is significantly higher than those of few-layer graphene and reduced graphene oxide. An in-depth understanding of the effect of the microstructure on the lithium storage behavior of graphene electrodes will provide an experimental basis for development of high-performance graphene electrodes.