Three-Dimensional Network Microstructure Design of the Li4Ti5O12/rGO Nanocomposite as an Anode Material for High-Performance Lithium-Ion Batteries

At present, the wide commercial application of Li4Ti5O12 (LTO) is limited as an anodefor lithium-ionbatteries because of its poor conductivity and lower rate performance.In this paper, LTO nanoparticles were embedded in a reduced grapheneoxide (rGO) conductive network by an in situ electrostatic self-assemblyeffect using a simple hydrothermal reduction method. The microstructureand electrochemical performance of the LTO/rGO composite were investigated.The highlighted results showed that LTO nanoparticles were combinedwith rGO nanosheets by a Ti-O-C covalent bond, whichwas more stable than other bonding methods. At the same time, theaddition of rGO not only enriches the structure and increases thespecific surface area but also effectively prevents the agglomerationof LTO. The higher conductivity of LTO nanoparticles was bestowedby the rGO three-dimensional (3D) network, causing structural stabilityand high electrochemical performance. The LTO/rGO composite has highfirst discharge capacity (643.9 mAh/g at 0.5C), remarkable rate performance(290 mAh/g at 10C), and excellent cycle stability (271.7 mAh/g afterthe 1000th cycle at 10C) when tested in a half battery. Furthermore,it has higher discharge capacity (181.8 mAh/g at 1C, the first Coulombicefficiency was 90.1%) and excellent cycle stability (142.8 mAh/g after500 cycles at 20C) when assembled into a full battery as the anodewith commercial LiFePO4 (LFP) as the cathode. The lithiumstorage mechanism of the LTO/graphene composite was further discussedby first-principles calculations. With the addition of graphene toLTO, the electron transport ability was improved and the diffusionenergy barrier was reduced. This made the composite expected to becomea promising anode material for lithium-ion batteries.