Voltage fade mitigation in the cationic dominant lithium-rich NCM cathode

Abstract

In the archetypal lithium-rich cathode compound Li1.2Ni0.13Co0.13Mn0.54O2, a major part of the capacity is contributed from the anionic (O2−/−) reversible redox couple and is accompanied by the transition metal ions migration with a detrimental voltage fade. A better understanding of these mutual interactions demands for a new model that helps to unfold the occurrences of voltage fade in lithium-rich system. Here we present an alternative approach, a cationic reaction dominated lithium-rich material Li1.083Ni0.333Co0.083Mn0.5O2, with reduced lithium content to modify the initial band structure, hence ~80% and ~20% of capacity are contributed by cationic and anionic redox couples, individually. A 400 cycle test with 85% capacity retention depicts the capacity loss mainly arises from the metal ions dissolution. The voltage fade usually from Mn4+/Mn3+ and/or On−/O2− reduction at around 2.5/3.0 V seen in the typical lithium-rich materials is completely eliminated in the cationic dominated cathode material.