The grain morphology and surface properties of a Li-rich Li2MnO3 cathode material: a first-principles study

Complex surface evolution plays a critical role in the rapid energy degradation of Li2MnO3 as a cathode material for high-energy-density Li-ion batteries. Here, we demonstrate that the defect-containing (001) surface of Li2MnO3 satisfies the stoichiometric relationship under air conditions and in the main experimental temperature window. For Li2MnO3 cathode materials, the surface area fraction of the terminals that satisfy stoichiometry (STO) can reach at least 70% when the synthesis environments are under Li&Mn-mid and Mn-rich conditions, while it is hard to exceed 40% under Li-rich conditions. All the stable surfaces exhibit excellent electrochemical properties, save the poor charge voltage and conductivity of the (001)_STO terminal. The low p-band center of O ions and stronger Mn–O bond strength effectively prevent the release of oxygen during Li-ion extraction in Li2MnO3. In addition, the low surface energy of the (001)_STO terminal and the high energy barrier between the different terminals dominates the dish-shape appearance of the grain morphology.