Deep discharge and elevated temperature cycling of LiMn _1.485Ni_0.45Cr_0.05O₄ spinel cathodes: Solid-state cell studies

LiNi_0.5-xMn_1.5Me_xO₄ (Me = Cr, Co, Fe, Al, Ga) (LNM) provides specific capacity of ca. 130 mAh/g between 5.0 V-3.5 V though discharge to 2 V can yield 250 mAh/g. Others have shown in liquid electrolyte cells that discharge to 2 V results in steep capacity fade associated with phase transitions below 3.5 V. We show that in thin-film cells, LNM can be cycled at 25°C and 100°C between 5 V-1.9 V with little capacity fade over 100-200 cycles. These findings suggest that rapid capacity fade of LNM at deep discharge for liquid electrolyte cells is not due to an inherent crystallographic limitation of LNM.