Pressure effects on the charge carrier transportation of polycrystalline LiCr_0.35Mn_0.65O₂

LiCr_0.35Mn_0.65O₂ powders were investigated by using in situ impedance spectroscopy under high pressure. The impedance spectroscopy of the Nyquist representation showed two overlapped arcs in the complex impedance plane which corresponded to the electrical transportation of grain and grain boundary respectively. By using the representation of Z ″/f versus Z ', the resistance and the relaxation frequency of grain and grain boundary were obtained under different pressures. It was found that at every phase transition region, both the resistance and the relaxation frequency of grain and grain boundary changed discontinuously. Pressure decreases the effective scattering section of grain and grain boundary to the charge carriers obviously and makes their transport easier. The variation of defects in the grain boundary region leads the sample resistance in the decompression process is much lower than that in the compression process. This indicates the pressure treatment has a positive contribution to the electrochemical performance of LiCr_0.35Mn_0.65O₂.