Electrochemical extraction of lithium from LiMn2O4

Lithium has been removed electrochemically at 15 μA/cm2 from LiMn2O4 (spinel) to yield single phase Li1−xMn2O4 for 0 < × ⩽ 0.60. The electrochemical curve suggests that beyond x = 0.60 an electrochemical process other than lithium extraction occurs. Powder X-ray-diffraction spectra indicate that during the extraction process the [Mn2]O4 framework of the spinel structure remains intact. Previous results have shown that 1.2 Li+ ions can also be inserted into LiMn2O4, which suggests that lithium may be cycled in and out of the [Mn2]O4 framework of the spinel structure over a wide range of x, at least from Li0.4Mn2O4 to Li2Mn2O4. Discussion of the mechanism of formation of λ-MnO2 in an acidic environment is extended.