Capacity Improvement by Nitrogen Doping to Lithium-Rich Cathode Materials with Stabilization Effect of Oxide Ions Redox

Lithium-rich cathode materials show higher theoretical capacity than conventional cathode materials because the redox activity of oxide ions in addition to the transition metal valence change contributes charge compensation during charge/discharge reactions. In this study, we prepared nitrogen-doped lithium-rich cathode materials, Li1.2Ti0.4Mn0.4O2, by using mechanical milling with Li3N. The optimized nitrogen-doped Li1.2Ti0.4Mn0.4O1.85N0.10 showed higher first charge capacity of 350 mAh g(-1) than that of the non-nitrogen-doped Li1.2Ti0.4Mn0.4O2 of 300 mAh g(-1). Soft X-ray absorption spectroscopy indicated that the extra capacity was contributed to by both Mn valence change and oxide ions redox.