Improved Electrochemical Performance of the 5 V Spinel Cathode LiMnsub 1.5Nisub 0.42Znsub 0.08Osub 4 by Surface Modification

The spinel with a cation-disordered structure has been surface modified with nanosize , ZnO, and by an electrostatic self-assembly method and characterized by X-ray diffraction, Fourier transform IR spectroscopy, high-resolution transmission electron microscopy, and electrochemical measurements. Although the modifications do not change the crystallographic structure of the spinel sample, the surface-modified samples exhibit better cyclability, rate capability, and rate capability retention on cycling compared to the bare . Among the various samples investigated, the surface modification with gives the best electrochemical performance. Electrochemical impedance spectroscopy measurements demonstrate that the improved performance on surface modification is due to a suppression of both the surface layer resistance and charge transfer resistance.