The addition of a moderate amount of a layered oxide like LiCoO2 to an optimized spinel oxyfluoride composition like LiMn1.8Li0.1Ni0.1O3.8F0.2 followed by charging to high- enough voltages (4.7 V) during first charge offers superior capacity retention at 60 degrees C in subsequent cycles at 4.3 - 3.5 V in lithium- ion cells fabricated with graphite anode. The trapping of trace amounts of protons that may be present in the electrolyte within the layered oxide lattice during the first charge to 4.7 V suppresses Mn dissolution and improves the electrochemical performance significantly, enhancing the commercialization prospects of spinel cathodes for hybrid electric vehicle applications. (c) 2007 The Electrochemical Society.