LATP ionic conductor and in-situ graphene hybrid-layer coating on LiFePO4 cathode material at different temperatures

摘要

In this work, a hybrid-layer coated LiFePO4/C (LFP/C) cathode material is investigated for the application of high temperature performance of Li-ion battery. The electrochemical performance of the material is significantly enhanced by improving its ionic and electronic conductivity via hybrid-layer coating, i.e., Li(1.4)Al(0.4)ATi(1.6)(PO4)(3) (LATP) and graphene nanosheets (GNS) layer. Initially, the LATP layer is coated by a sol-gel method and later, the in-situ GNS layer is coated through a wet chemical process. The characteristic properties of LFP/C@LATP@GNS composite are examined by various spectroscopy and microscopy method. The electrochemical performances of LFP/C@LATP@GNS cathode material have been evaluated at different temperature such as -20 degrees C, 25 degrees C and 55 degrees C. The best electrochemical performance is observed at 55 degrees C with the discharge capacities of 160, 156, 154, 153, 149, 144, and 130 mAh g(-1) at 0.1C, 0.2C, 0.5C, 1C, 3C, 5C, and 10C rate, respectively. Due to its higher ionic and electronic conductivity, the long cycle-life is obtained for LFP/C@LATP@GNS cathode material at 55 degrees C, which is maintained over 500 cycles at 10C rate with the fading rate of ca. 8.76%. Hence, the dual-layer coating on LFP cathode material is the superior method to develop the high performance Li-ion battery for electric vehicles. (C) 2018 Elsevier B.V. All rights reserved.