Controlled Formation of Li4Ti5O12-C Hollow Hybrid Microspheres for an Improved Battery Performance in Lithium Ion Batteries

Abstract

The In this contribution, we reported our progress on the construction and optimization of the hybrid structure of Li4Ti5O12-Carbon (LTO-C) for their application as an anode material in lithium ion batteries. By means of a template-free process, uniform hollow hybrid microspheres (HHMs) of LTO-C has been prepared with delicate control on the central cavity and the nanocomposite wall, which was composed of a crystalline LTO matrix with conductive carbon well dispersed inside. The synthesis protocol for LTO-C was very convenient, low-cost, environmentally benign, and suitable for large-scale production. We identified that the hollowing process is induced by the gradual crystallization of solid microspheres whose crystallinity was relatively low at the beginning. The high temperature treatment initiated a progressively-inward crystallization starting from the particle surface: Crystallization firstly happened on the surface, and then marched into the core as evidenced by a steady encroachment of the crystallization frontline towards the center, resulting in the formation of the central cavity due to the increased tension inside. We demonstrated that such a synthetic platform for hollow microspheres were versatile and could be readily applicable for the synthesis of different kinds of metal oxides HHMs. By using the LTO-C as an anode material, we confirmed the advantage of the HHMs structure for their application in lithium ion batteries as revealed by the much higher discharge capacity and much improved rate capability. Figure 1: a) SEM images of the TiO2-UF precursors which exist as uniform solid nanospheres. b) SEM image of the FIB-prepared cross section of the LTO-C HHMs sample, showing the hollow nature of the inner particles. c) The first charge/discharge curves at 0.1 C for different samples tested, showing the advantage of the LTO-C HHMs one as compared to those control samples with either no cavity or no carbon matrix. d) Cyclablity test results for different samples. Figure 1