PROTON INSERTION AND LITHIUM-PROTON EXCHANGE IN SPINEL LITHIUM MANGANATES

The protonic species formed in spinel lambda-MnO2 by proton exchange f or lithium ions in Li1+xMn2-xO4 precursors have been characterised by infrared and inelastic neutron scattering spectroscopies. Proton diffu sion into the lattice appears to depend on the presence of octahedral manganese vacancies, with formation of lattice hydroxyl co-existing wi th water. Mechanisms of proton transfer are considered in relation to lithium-proton exchange during reinsertion of lithium into the materia ls, and for insertion of additional protons by chemical reduction.