Regulating Oxygen Redox Process to Mitigate Voltage Decay and Hysteresis of Li-Rich Mn-Based Layered Cathodes

Abstract Li-rich Mn-based layered oxides (LLOs) are regarded as one of the most promising next-generation cathodes for lithium-ion batteries (LIBs) due to their ultra-high capacity and low cost. However, the redox behavior of oxygen under high voltage induces severe challenges, including voltage hysteresis and voltage decay, which have become major obstacles to their commercialization. This work optimizes the oxygen redox process of O2-type LLOs by regulating the Na content in P2-type Na-based intermediates. Experimental results demonstrate that samples prepared by intermediates with optimal Na content show higher reversibility and reduction potential of oxygen redox. Meanwhile, the migration and dissolution of transition metals in the optimized samples are effectively suppressed. Therefore, the optimized samples deliver an improved voltage stability and alleviated voltage hysteresis. This work suggests that the oxygen redox process can be regulated and provides a practical solution to mitigate voltage decay and hysteresis in LLOs.