Sponge-Like Li4Ti5O12 Constructed on Graphene for High Li Electroactivities

Abstract

A sponge-like Li4Ti5O12/graphene composite was prepared via sequential hydrothermal process and solid-state heat treatment process for the application to high-power lithium ion batteries. The as-prepared electrode showed outstanding Li electroactivities with a rapid and reversible Li insertion/extraction of up to 10 C-rate (1.75 A/g). It delivered a discharge capacity of 174 mAh/g at 0.5 C, near the theoretical capacity of Li4Ti5O12, with good rate capability and cyclic stability. First-principles calculations revealed the intimate interaction of the Li4Ti5O12 and graphene, which implies that graphene functions as an 'electron tunnel.' Electrochemical impedance spectroscopy also proved that the graphene-hybridization and the unique structure of the Li4Ti5O12 material significantly reduce the resistive behavior of electrodes. The 3D structured Li4Ti5O12/graphene hybrid reported herein could be a promising candidate for a safe, low-cost, high-power anode for lithium ion batteries, and our seeding-growth-sintering method for decorating graphene with active material will offer an effective upgrade on highly insulating Li4Ti5O12 materials.