LiMnO2

LiMnO2 (lithium manganese oxide) is a transition-metal oxide and a potential cathode material for lithium-ion batteries. In the commonly studied layered form, Li and Mn ions occupy alternating layers in a close-packed oxide lattice, similar to LiCoO2, and it is often described as an α-NaFeO2-type structure. In the ideal stoichiometry, manganese is in the +3 oxidation state, and during charging Li+ ions are removed with concomitant oxidation of Mn3+ to Mn4+. The material, however, suffers from Jahn-Teller distortions associated with Mn3+ that drive structural changes and phase transitions during cycling, leading to limited capacity retention.

Synthesis typically involves solid-state reaction of Li-containing precursors (such as Li2CO3) with manganese oxides or carbonates at high temperature, often followed by careful cooling. The LiMnO2 phase is relatively unstable in air and moisture and can transform into spinel or other phases; performance is often improved by cation substitution (for example with Ni, Co, or Mg) or by surface coatings and nano-structuring to suppress distortions and Mn dissolution.

Electrochemical performance is hampered by structural instability; the theoretical capacity is about 285 mAh/g if fully delithiated, but practical capacities are usually much lower, and cycle life is limited without stabilization strategies. Researchers study LiMnO2 as a lower-cost alternative to cobalt-containing cathodes and as a component in Li-rich or doped layered oxides, where improvements in stability and rate capability are pursued.

LiMnO2 has been the subject of extensive research for use in next-generation lithium-ion batteries, with focus on addressing its structural and chemical stability to unlock its potential.