Effect of SEI on Capacity Losses of Spinel Lithium Manganese Oxide/Graphite Batteries Stored at 60°C

The discharge capacities of spinet-type Li(1.1)Mn(1.9)O(4)/graphite cells charged in electrolytes with solid electrolyte interphase (SEI)-forming additives are investigated after being stored at 60 degrees C. The presence of Mn deposits on the anode surface, which is responsible for the capacity fading of cells, is clearly shown by means of open-circuit voltage, ex situ X-ray diffraction, and energy-dispersive spectrometry measurements. Unlike fluoroethylene carbonate, using vinylene carbonate as an SEI former leads to a noticeable improvement in the discharge capacity retention of cells that were stored for 20 days at 60 degrees C. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3481711] All rights reserved.