The Influence of Different Types of Graphene on the Lithium Titanate Anode Materials of a Lithium Ion Battery

Abstract

Graphene is widely studied in various fields, due to its high electrical conductivity and thermal conductivity, as well as its large theoretical surface area. Graphene is used in batteries to improve the electronic conductivity of the material and to reduce the volume effect that the electrode material has during the charging and the discharging process. The graphene nanosheets (GNS) and the electrochemical properties of the composite of battery electrode material differ, due to the different preparation methods used for commercial GNS. Two types of commercial GNS were evaluated via XRD, Raman spectra, and HR-TEM. Li4Ti5O12/graphene nanosheet (LTO/GNS) composites were obtained with a sol-hydrothermal process with in situ additions of GNS. Both the LTO/GNS composites showed the same microstructure. The GNS in the composites provided conductive connections for LTO to establish a conductive network. The effect that GNS with low structural defects had on improving the electrical conductivity of the LTO/GNS was better than the GNS with additional structural defects. The LTO/GNS (with low structural defects) exhibited superior electrochemical performance than the LTO/GNS (with additional structural defects). Moreover, the LTO/GNS samples with additional structural defects obtained a lower specific capacity than the pure LTO samples, in terms of the rate performance measurements. The possible causes were analyzed throughout this study.