Reversibility of lithium intercalation in lithium and sodium phyllomanganates

The cycling of sodium and lithium phyllomanganates in liquid lithium batteries was investigated both by galvanostatical and potentiostatical methods. Slow-scanning voltammograms show the occurrence of a single-phase reaction extending from 3.1 to 2.6 V on discharge for both compounds. On cycling, the voltammogram of Li phyllomanganate smears out, while the current peak narrows in the case of Na. In both cases, the initial capacity of not, vert, similar240 Ah/kg drops continuously on cycling between 2 and 4 V. X-ray diffraction shows an important disordering with cycling, with the possible emergence of a cubic-packed, spinel-like structure.