Solid coated Li4Ti5O12 (LTO) using polyaniline (PANI) as anode materials for improving thermal safety for lithium ion battery

Abstract

In generally, the thermal behaviour of cathode and electrolyte are the major concerns for the safety of lithium-ion battery, In contrast to rare attention on thermal effects of anode materials. In this work, Li4Ti5O12/polyaniline (PANI@LTO) composites were synthesized by solid coating method. The SEM/TEM images of the PANI@LTO composites reveal that the PANI nanorods were crashed and wrapped around the LTO particles. FTIR analysis shows the interaction between the NH groups and the surface of the LTO material by mechanical action, which cause changes of oxidation state of PANI in the PANI@LTO composites, compared with the pristine PANI materials. As an anode material for lithium ion battery, the PANI coatings have improved the rate performance of the LTO materials. The specific capacities of the composite at rates of 2C and 5C are 137.8, and 117.2 mAhg, which are higher than those of the pristine LTO (99.5 and 77.6 mAhg, respectively) materials. In addition, the PANI@LTO composites show better cycling stability at 2C rates, after 100 cycles maintained 74.3%, compared to 60.4% of the pristine LTO materials. For thermal behaviour, the test was conducted under 60 °C at 2C rate, the initial capacity of the PANI@LTO composites was 152.5 mAhg that is higher than the value of 137.8 mAhgat room temperature. However, the pristine LTO materials show similar initial capacity with that at room temperature. In addition, the PANI@LTO composites maintain better thermal stability, the capacity of the PANI@LTO composites were retained 83.2% after 80 cycles at 60 °C, compared to 54% loss on the LTO electrode under same condition. These results suggest that PANI might be a promising material to improve capacity and benefit thermal safety of lithium ion battery.