Excellent electrochemical performance of lithium manganese composite decorated with poly(ethylene glycol) and carbon nanotube

摘要

To significantly improve the electrochemical performance of LiMn2O4, we proposed a simple and low-cost co-modification approach based on the synergistic effect of poly(ethylene glycol) (PEG) and carbon nanotubes (CNT). The CNT@PEG@LiMn2O4 (CNT@PEG@LMO) composite was prepared by ultrasound assisted wet-coating method. PEG is a highly conductive ionic conductor, which can improve the transport efficiency of lithium ions, and CNT is a good electronic conductor, which possesses excellent electrical conductivity. Moreover, the combination of PEG and CNT can effectively inhibit the dissolution of manganese and promote the uniform distribution of LiMn2O4 octahedra. The structure and surface morphology of the CNT@PEG@LMO composite were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical test result showed that the initial discharge capacity of the CNT@PEG@LMO composite could reach up to 123.8 mAh g(-1) at 1.0 C with capacity retention of 95.2 % after 100 cycles, which is higher than that of the unmodified LiMn2O4 sample. The high-rate capability of the CNT@PEG@LMO composite was significantly improved. When cycled at 55 degrees C, the CNT@PEG@LMO composite could show good cycling stability and rate performance. Such excellent electrochemical performance is due to close association with the synergistic effect of PEG and CNT.