Sol–gel preparation of cobalt manganese mixed oxides for their use as electrode materials in lithium cells

• Published in: Electrochimica acta Vol. 52; no. 28; pp. 7986 - 7995
• Main Authors: Lavela, P., Tirado, J.L., Vidal-Abarca, C.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.2007; Elsevier
• Subjects: Applied sciences; Batteries; Citrate; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Exact sciences and technology; Impedance; Lithium; Sol–gel; Citrate; Lithium; Batteries; Sol–gel; Impedance; Ternary compound; Scanning electron microscopy; Cycling; Cobalt Oxides; Sol-gel; Transition metal; Secondary cell; Electrode material; X ray diffraction; Discharge; Surface structure; Lithium battery; Sol gel process; Spinels; Morphology; Preparation; Manganese Oxides; Specific capacity; Electrical characteristic; Electrical impedance
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2007.06.066

An ethanol dehydration procedure has been used to precipitate gel-like citrate precursors containing cobalt and manganese transition metal ions. Further annealing led to the Mn x Co 3− x O 4 spinel oxide series ( x: 1, 1.5, 2, 3). Annealing temperature and treatment time were also evaluated to optimize the performance of the oxides as active electrode materials in lithium cells. The manganese–cobalt mixed oxides obtained by this procedure were cubic or tetragonal phases depending on the cobalt content. SEM images showed spherical macroporous aggregates for MnCo 2O 4 and hollow spheres for manganese oxides. The galvanostatic cycling of lithium cells assembled with these materials demonstrated a simultaneous reduction of cobalt and manganese during the first discharge and separation of cobalt- and manganese-based products on further cycling. As compared with binary manganese oxides, a notorious electrochemical improvement was observed in the mixed oxides. This behavior is a consequence of the synergistic effect of both transition metal elements, associated with the in-situ formation of a nanocomposite electrode material when cobalt is introduced in the manganese oxide composition. Values higher than 400 mAh/g were sustained after 50 cycles for MnCo 2O 4.