Enhanced the electrochemical performance of Li4Ti5O12 anode materials by high conductive graphene nanosheets

Abstract

Li4Ti5O12/graphene nanosheets (LTO/GNSs) composites are prepared in situ via a sol–hydrothermal process. The LTO are found on the edges and surface of the GNSs, and GNSs give a conductive connection of LTO spheres to constitute a conductive network to improve the specific capacity and high-rate performance of LTO. With the increase of the amount of graphene nanosheets from 0 to 10 wt%, the electrical conductivity of composites increase from 1.78 × 10−9 S cm−1 to 2.04 S cm−1. However, the specific capacity of LTO/GNSs-10 wt% electrode at lower rate (≤5 C) (1C = 175 mAh g−1) is not greater than that of LTO electrode because of the high content of GNSs and the low specific capacity of GNSs at the potential range of 1.0 and 2.5 V. But at higher-rate (10 and 20 C in the investigation), electrical conductivity becomes the main factor affecting the specific capacity, so its specific capacity is greater than that of LTO electrode. LTO/GNSs-3 wt% composite shows the highest specific capacity and the best high-rate performance with good cycling performance. The significantly improved high-rate capability of the LTO/GNSs composites are mainly attributed to the improved electrical conductivity, the lower polarization of potential difference, the larger diffusion coefficient of lithium ion and smaller charge transfer resistance than LTO electrode.