Preparation and Characterization of Li[sub 1.05][Ni[sub 0.35]Co[sub 025]Mn[sub 0.4]]O[sub 2] as a Cathode Material for Rechargeable Lithium Cells

Abstract

A lithium insertion material Li 1 . 0 5 [Ni 0 . 3 5 Co 0 . 2 5 Mn 0 . 4 ]O 2 was synthesized by a sol-gel method. The structural and electrochemical properties of the sample were investigated using X-ray diffraction spectroscopy (XRD) and the galvanostatic charge-discharge method. Rietveld analysis of the XRD patterns shows this compound as having the α-NaFeO 2 structure (R3m; a = 2.8670(4) A, and 14.279(3) A in hexagonal setting). Li 1 . 0 5 [Ni 0 . 3 5 Co 0 . 2 5 Mn 0 . 4 ]O 2 has a discharge capacity of 164 mAh/g in the voltage range 2.8-4.5 V vs Li/Li + , a stable capacity on cycling, and good rate capability in the current range 0.1-4.0 C. When the voltage range is increased to 2.8-4.8 V, it yields a capacity of 187 mAh/g, but exhibits a significant loss of capacity during cycling. The results indicate that this novel cathode material should be useful for lithium-ion cells because it has a lower cost than LiCoO 2 -containing cells, and high performance.