DOI: https://doi.org/10.15407/akademperiodyka.444.108
Precipitation of hydroxides and carbonates from solutions containing complex compounds is a valuable industrial process enabling one to synthesize electrode materials with high density particles of microspherical morphology and high tap density. As a complex formation agent, ammonia is almost exclusively used in this process. Aiming at the search of other complex formation agents and the detailed studies of complex formation at precipitation, we have first investigated the hydrolysis of solutions containing citric acid. Equilibria in solutions containing citrate complexes of manganese and carbonates are computed. It is found that in Mn(NO3)2 – хC6H8O7∙H2O – уNa2CO3 systems, a neutral Mn(HCitr) complex dominates up to pH=9.5 and precipitation of MnCO3 from carbonate containing solutions begins at рН~6.5. Experiments show that MnCO3 precipitates from these systems in the form of openwork quasi-spherical aggregates formed by nanosized crystals. The synthesis of LiMn2O4 from this precursor does not influence the morphology of the material, and the resulting product consists of aggregates of less than 4 mkm and nanocrystals of ~90 nm. Electrochemical tests evidence that for the best samples, the specific capacity of 103 mAh/g can be achieved at 1 C current. At 20 C current, they deliver ~25 mAh/g capacity. After high-rate tests, in control cycles with 1 C current, the samples demonstrate high capacity retention, returning up to 98% of their initial capacity. This signifies their good prospects for using in high-rate batteries.