Improvement of the overall performances of LiMn2O4 via surface-modification by polypyrrole

Abstract Polypyrrole (PPy) is an excellent conductive polymer and the study on its utilization in the surface modification of the LiMn2O4 (LMO) is few. In this work, the structure, morphology and electrochemical performance of surface-modified LiMn2O4 composites with PPy and polyimides (PI) were discussed. The crystal structure, chemical bonds and morphology were characterized through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. Moreover, the specific power and cycling performance were tested at room and high (55 °C) temperature. The PPy@LMO (surface-modified LMO composites with PPy) shows better performances than the pristine LMO. The addition of PPy not only weakens the corrosion caused by electrolyte, but also improves the discharge capacity at higher rates. The charge transfer resistance of the PPy@LMO is much lower than that of the pristine LMO after cycling.