Enhanced High Temperature and Rate Capability Performance of Nanoscale Lithium Titanate (Li4Ti5O12) Anode

Abstract

Lithium titanate, Li4Ti5O12 (hereafter denoted as LTO) is an attractive anode material for high rate lithium-ion batteries. However, at high temperatures (above 50°C), LTO suffers from surface phase transitions that lead to severe gas generation issue. In this work, nanoscale LTO material was synthesized by water-based spray drying method followed by a high-temperature calcination to enhance the overall electrochemical performance. The synthesized material were found to be consisted of round shaped secondary particles which were formed by the association of large number of LTO primary particles (< 200 nm size). The nanoscale LTO anode material exhibited very stable electrochemical performance at high temperature (50°C) and high rate (5C) which can be attributed to the shortened lithium-ion diffusion lengths. Rate capability and impedance spectroscopy were also performed to further study the electrochemical properties. To better understand the structural behavior, cells were torn down after 1 cycle and 500 cycles. High resolution transmission electron microscope and selective area electron diffraction results revealed that the thickness of the LTO phase transitions layer after 500 cycles is almost the same as that after 1 cycle, around 3-5 nm.