Effect of the Thermal Treatment on the Particle Size and Electrochemical Response of LiCr0.2Mn1.8O4 Spinel

• Published in: Journal of the Electrochemical Society 2005-01, Vol.152 (2), p.A301-A306
• Main Authors: Pascual, L, Gadjov, H, Kovacheva, D, Petrov, K, Herrero, P, Amarilla, J M, Rojas, R M, Rojo, J M
• Format: Article
• Language: English
• ISSN: 0013-4651
• DOI: 10.1149/1.1839558

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 1100DGC) 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 1100DGC 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.