Preparation of Li4Ti5O12 Microspheres with a Pure Cr2O3 Coating Layer and its Effect for Lithium Storage

Abstract

The pure Cr2O3 coated Li4Ti5O12 microspheres were prepared by a facile and cheap solution-based method with basic chromium(III) nitrate solution (pH=11.9). And their Li-storage properties were investigated as anode materials for lithium rechargeable batteries. The pure Cr2O3 works as an adhesive interface to strengthen the connections between Li4Ti5O12 particles, providing more electric conduction channels, and reduce the inter-particle resistance. Moreover, LixCr2O3, formed by the lithiation of Cr2O3, can further stabilize Li7Ti5O12 with high electric conductivity on the surface of particles. While in the acid chromium solution (pH=3.2) modification, besides Cr2O3, Li2CrO4 and TiO2 phases were also found in the final product. Li2CrO4 is toxic and the presence of TiO2 is not welcome to improve the electrochemical performance of Li4Ti5O12 microspheres. The reversible capacity of 1% Cr2O3-coated sample with the basic chromium solution modification was 180 mAh/g at 0.1 C, and 134 mAh/g at 10 C. Moreover, it was even as high as 127 mAh/g at 5 C after 600 cycles. At −20 °C, its reversible specific capacity was still as high as 118 mAh/g.