Proton insertion in spinel lithium manganates and the effect of manganese substitution

Lithium manganate spinels with the formula Li1+xMn2-xO4 undergo lithium <-> proton ion exchange to give a defect lambda-MnO2 phase which can act as a lithium selective sorbent. The substitution of manganese by other metals, s uch as Co, Cr, Ti and Ga allow the structural properties of the spinel latt ice to be modified and tailored. This work uses neutron diffraction, inelas tic neutron scattering, XAFS and atomistic calculations to show that in the non-substituted spinel, inserted protons are present predominantly as hydr oxyl groups directed into the vacant sa site, with an orientation influence d by the presence of manganese vacancies. The influence of cation substitut ion is explained within this context. (C) 2000 Elsevier Science B.V, All ri ghts reserved.