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Spinel of composition LiCr0.2Mn1.8O4 has been synthesized by a combustion-aided procedure. The particles of the sample are single crystals of ca. 10 nm size as deduced from X-ray diffraction and transmission electron microscopy. Thermal treatment of the as-prepared sample at increasing temperature (400, 600, 700, 750, 900, 1000, and 1100°C) for different times (1, 3, or 24 h) leads to an increase of the particle size, which attains a value as high as 1560 nm after heating at 1100°C for 1 h. Electrochemical response of the heated samples as positive electrodes in a lithium cell has been studied at three rates (C/24, C, and 3C; where C=2.9 mA). At C/24 the discharge capacity measured at 4 and 4.8 V is not appreciably affected by the particle size. At C and 3C the discharge capacity measured at those voltages decreases as the particle size increases; a linear dependence has been found for particle sizes above 50 nm. On cycling we have found that the capacity fade also depends on the particle size; the larger the particles the less the capacity fade at the mentioned voltages. © 2004 The Electrochemical Society. All rights reserved.

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