Synthesis of spinel-type lithium antimony manganese oxides and their Li+ extraction/ion insertion reactions

Spinel-type lithium antimony manganese oxide was first synthesized by aging the precipitates that were obtained by reaction of a mixed aqueous solution of manganese(II) and antimony(V) chlorides (Sb/Mn = 0.25) with (LiOH + H2O2) solution, followed by hydrothermal treatment at 120 degrees C. A well crystallized spinel-type solid with a chemical composition of Li1.16Sb(V)(0.29)Mn(III)(0.77)Mn(IV)(0.77)O-4 was obtained; it had the characteristic of including mixed valence manganese. The spinel structure was preserved during heating up to 600 degrees C. Most of the lithium ions in the prepared material could be extracted by treating with an acid; the extraction progressed topotactically, preserving the spinel structure, accompanied by a decrease in the lattice constant from 8.31 +/- 0.01 Angstrom to 8.13 +/- 0.01 Angstrom. The mean oxidation of manganese increased from 3.50 to 3.98 after acid treatment, due to the disproportionation of trivalent manganese. The DTA-TG analysis and IR spectra showed the formation of lattice protons exchangeable with lithium ions. The pH titration study showed that the acid treated sample had a remarkable lithium ion-sieve property over the entire pH range studied. The affinity order was K < Na << Li and the exchange capacity reached 5.6 mmol g(-1) for Li+. It showed a selective uptake of 14 mg g(-1) of Li+ from LiCl enriched seawater.