Sufficient Oxygen Redox Activation against Voltage Decay in Li-Rich Layered Oxide Cathode Materials

Oxygen-redox-based Li-rich layered oxide cathode materials always suffer from severe voltage decay, because of progressively structural transformation. An initial consensus is that less utilization of oxygen redox in these cathodes would retard this process on cycling. In this work, we find sufficient oxygen redox in Li1.26Ni0.0741Co0.0741Mn0.593O2 that contributes toward the available capacity of 80.5% can deliver a specific capacity of 280 mAh g(-1) with the retentions of voltage and capacity of similar to 96.7% and 97.1% after 50 cycles, respectively. The suppressed voltage decay with sufficient oxygen redox is originated from the stabilizing effect of vast disordered structures generated by the initial electrochemical activation. Based on a unique disorder-order transition induced by temperature, the degree of the concentration of the disordered structures is well-revealed through temperature-dependent in situ X-ray diffraction and Raman spectroscopy. The abundant disordered structures via sufficient oxygen redox activation are believed to act as an accommodator to promote structural stability.

Automated summary

In this study, it was found that sufficient oxygen redox can suppress voltage decay and improve structural stability. The concentration of disordered structures can be controlled by temperature, revealing the mechanism of structural stability.