(Li, Al)-co-doped spinel, Li(Li0.1Al0.1Mn1.8)O4 as high performance cathode for lithium ion batteries

(Li, Al)-co-doped manganese oxide spinel compounds, Li(Li0.1Al0.1Mn1.8)O-4 are prepared at temperatures (T), 600, 650 and 750 degrees C by polymer precursor method using polyvinyl pyrrolidone (PVP). The structure and morphology of the porous and sub-micron size particles of the compounds are characterized by the Rietveld refined X-ray diffraction (XRD), infrared and Raman spectroscopy, scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and Brunauer, Emmett and Teller (BET) surface area techniques. Galvanostatic charge-discharge cycling in the voltage range of 3.5-4.3 V vs. Li at various current (C) rates, 0.5-3 C at 24 degrees C up to 60 cycles and at 0.5 C and at 55 degrees C up to 50 cycles is carried out. The influence of the Li-excess, the type of Al3+ dopant cation and the amount of fuel (polyvinyl pyrrolidone) used in the synthesis on the electrochemical behavior of the spinel in a Li-cell at room (24 degrees C) and at elevated temperature (55 degrees C) has been studied. Results show that at 24 degrees C and at 0.5 C, the phases prepared at 600 degrees C (I) and 650 degrees C (II) showed reversible capacities of 79 and 105 mAh g(-1) and retained 99 (+/- 1)% of the capacity after 50 cycles. At 1 C, 2 C and 3 C rates, II showed stable capacities of 97, 83 and 57 mAh g(-1), respectively. At 55 degrees C and at 0.5 C, II showed a reversible capacity of 114 mAh g(-1) and retains 92% of it at the end of 50 cycles, signifying the best cathodic performance for a doped-LiMn2O4. Complementary cyclic voltammetry, impedance spectra and ex situ XRD data are described and discussed. (C) 2012 Elsevier Ltd. All rights reserved.