Mechanism of Capacity Fading Caused by Mn (II) Deposition on Anodes for Spinel Lithium Manganese Oxide Cell

The capacity fade of spinel lithium manganese oxide in lithium-ion batteries is a bottleneck challenge for the large-scale application. The traditional opinion is that Mn( II) ions in the anode are reduced to the metallic manganese that helps for catalyzing electrolyte decomposition. This could poison and damage the solid electrolyte interface ( SEI) film, leading to the the capacity fade in Li-ion batteries. We propose a new mechanism that Mn( II) deposites at the anode hinders and/or blocks the intercalation/ de-intercalation of lithium ions, which leads to the capacity fade in Li-ion batteries. Based on the new mechanism assumption, a kind of new structure with core-shell characteristic is designed to inhabit manganese ion dissolution, thus improving electrochemical cycle performance of the cell. By the way, this mechanism hypothesis is also supported by the results of these experiments. The LiMn2-xTixO4 shell layer enhances cathode resistance to corrosion attack and effectively suppresses dissolution of Mn, then improves battery cycle performance with LiMn2O4 cathode, even at high rate and elevated temperature.