Adverse effect of Ag treatment on the electrochemical performance of the 5 V nanometric spinel LiNi0.5Mn1.5O4 in lithium cells

The effect of coating the nanometric spinel LiNi0.5Mn1.5O4 with Ag on its rate capability was studied. The X-ray photoelectron spectroscopy (XPS) concentration depth profiles obtained reveal that the intensity of the Ag 3d peak remains unchanged for a long sputtering time, so the spinel particles do not seem to be coated by an Ag layer. The effect is detrimental at high charge/discharge rates and the addition of silver significantly degrades the rate capability of the spinel. Ag oxide nanoclusters formed in the first charge process possibly establish a barrier that hinders transfer of the high ion flux between the electrolyte and electrode. (c) 2005 The Electrochemical Society.