High-energy and high-power Li-rich nickel manganese oxide electrode materials

A lithium-rich nickel-manganese oxide compound Li(x)(Ni(0.25)Mn(0.75))O(y) (x>1) was synthesized from layered Na(0.9)U(0.3)Ni(0.25)Mn(0.75)O(8) precursor using a lithium ion-exchange reaction. The electrochemical behavior of the material as a cathode for lithium batteries, and a preliminary discussion of its structure are reported. The product Li(1.32)Na(0.02)Ni(0.25)Mn(0.75)O(y) (IE-LNMO) shows broad X-ray diffraction peaks, but possesses a high intensity sharp (003) layering peak and multiple peaks with intensity in the 20-23 degrees 2 theta region which suggest Ni-Mn ordering in the transition metal layer (TM). Li/IE-LNMO cells demonstrate very stable reversible capacities of 220 mAh/g @ 15 mA/g and possess extremely high power of 150 mAh/g @ 1500 mA/g (15C). The Li/IE-LNMO cell dQ/dV plot exhibits three reversible electrochemical processes due to Ni/Mn redox behavior in a layered component, and Mn redox exchange in a spinel component. No alteration in the dQ/dV curves and no detectable change in the voltage profiles over 40 cycles were observed, thus indicating a stable structure for lithium insertion/extraction. This new material is attractive for demanding Li-ion battery applications. (C) 2010 Published by Elsevier B.V.