Deterioration of a Li-ion battery charged to an elevated voltage is investigated. Insertion of an insulating layer consisting of TiO2 powders and PVDF binder between the cathode and the separator suppresses the self-discharge during a storage test at 60 degrees C. This layer prevents the carbonization of the separator by oxidative cathode and this effect is greater when the insulating layer is placed on the cathode than on the separator. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.070203jes] All rights reserved.