QUALITY-CONTROL OF LI1-MN2-DELTA-O4 SPINELS WITH THEIR IMPURITY PHASES BY JAEGER AND VETTER TITRATION(DELTA)

Powders of lithium manganese oxide phases are synthesised and characte rised for possible application in a Li-ion battery. A modified phase d iagram on the basis of the manganese oxidation state and content is us ed to interpret the results. X-ray diffraction, flame atomic absorptio n spectroscopy, and Jaeger and Vetter titration are performed in order to classify the synthesised powders. The experiments reveal powders o f Li1+deltaMn2-deltaO4 (0<delta<0.2, i.e. 0<Li/Mn<0.65). with a spinel structure. At higher Li/Mn ratios mixtures of Li1.2Mn1.8O4 and Li2MnO 3 are formed. Spinels with small delta-values are favoured since they are more stable than the pure LiMn2O4, but they have still acceptable capacity. Also, aluminium-doped spinel materials with the composition Li1-deltaAlnMn2-delta-nO4 (0<n<0.3, delta=0.0645) are synthesised and characterised. However, no improvement in terms of capacity is found. (C) 1997 Elsevier Science S.A.