Li-Rich Layered/Spinel Cathode Composite 3/4[Li2MnO3·LiCxO2]·1/4[LiCxMnO4] (Cx = Cr1-yCoy) for Li-Ion Batteries

Abstract

A new series of Li-rich layered/spinel Li-Cr-Co-Mn-O composites are designed and investigated in this article. The high voltage spinel LiCxMnO4 (Cx = Cr1-yCoy) materials are embedded into lithium-rich layered materials and these Li-rich layered/spinel integrated structures exhibit both superior reversible capacities and high rate capabilities as cathode materials for lithium-ion batteries. The Li-rich layered/spinel 3/4[Li2MnO3·LiCxO2]·1/4[LiCxMnO4] (Cx = Cr1-yCoy) composites are synthesized with sol-gel method. XRD, HRTEM and fast Fourier transform (FFT) analysis demonstrate the integrated structure of Li-rich layered component and spinel phase. The electrochemical investigations performed within a wide potential window show an excellent result of the materials with the proper ratio between Co and Cr. All the composite materials exhibit initial discharge capacities over 200 mAh g−1. In particular, y = 0.4 and 0.6 samples show preferable cycling stability among the investigated materials, which is primarily attributed to the high reversible capacity of Li-rich layered component and 3D Li-ion diffusion channels of spinel phase, as well as low charge transfer resistance and Warburg diffusion impedance owing to the synergistic effect of the proper ratio between Co and Cr elements in these composites.