Continued improvement in the electrochemical performance of Li-Mn-O oxide cathode materials is key to achieving advanced low-cost Li-ion batteries with high energy densities. In this study, O2-type Li0.78[Li0.24Mn0.76]O2 nanowires were synthesized by a solvothermal reaction to produce P2-type Na5/6[Li1/4Mn3/4]O2 nanowires, which were then subjected to molten salt Li-ion exchange. The resulting nanowires have diameters less than 20 nm and lengths of several micrometers. The full-Mn-based nanowires cathode material delivers a reversible capacity of 275 mAh g-1 at 0.1 C and 200 mAh g-1 at a high current rate of 15 C with a capacity retention of more than 80% and the voltage decay was dramatically suppressed after 100 cycles. This excellent performance is ascribed to the highly stable oxygen redox reaction and lack of layered-to-spinel phase transition in the O2-type structure during cycling.
Keywords: Lithium-ion batteries; O2-type Li0.78[Li0.24Mn0.76]O2 nanowires; high power density; oxygen redox; voltage stability.