Investigation on process mechanism of a novel energy-saving synthesis for high performance Li4Ti5O12 anode material

Abstract

Li4Ti5O12 (LTO) anode material demonstrates superior cycling performance due to its stable spinel structure and high lithiation/de-lithiation potential. Herein, a novel energy-saving solid-phase synthesis route for LTO has been successfully designed, employing the cheap industrial intermediate product of metatitanic acid (HTO) as titanium source. Through the in-situ Fourier transform infrared spectroscopy (FTIR) and ex-situ X-ray diffraction (XRD), it is revealed for the first time that the amorphous crystal structure of HTO is more conducive for the Li+ insertion, making it possible to prepare LTO at a relatively lower sintering temperature. Utilizing the dehydration carbonization reaction between glucose and sulfuric acid, an ingenious strategy of glucose pre-coating is adopted to avoid the generation of Li2SO4 impurity caused by the residual sulfuric acid on the surface of HTO, which meanwhile enhances the conductivity and inhibits the particle growth of LTO. The obtained ALTO@C anode material consequently exhibits excellent electrochemical performance that 132.0 mAh g−1 is remained even at 20 C, and ultra low decay rate of 0.015% per cycle is achieved during 1000 cycles at 2 C. Remarkably, LiCoO2//ALTO@C full cell delivers conspicuous low-temperature property (130.7 mAh g−1 at 0.5 C and almost no attenuation after 300 cycles under −20 °C).