First-principles study on the initial reactions at LiNi1/3Co1/3Mn1/3O2 cathode/electrolyte interface in lithium-ion batteries

LiNi_1/3Co_1/3Mn_1/3O₂ (NCM) is a promising cathode material in Lithium-ion batteries with large capacity and high voltage. However, the capacity fading mechanism and long-term cycling behavior remain a significant problem. It has been reported that these problems are related to kinds of irreversible reactions on the electrode/electrolyte interface, such as decomposition of electrolyte and the dissolution of transition metal ions. Unlike anode materials, the interface between cathode and electrolyte is still lack of information. In this work, ab initio calculations based on density functional theory were performed to examine the initial reactions at NCM/electrolyte interface. The atomistic model of NCM and the slab models of different facets were built. Moreover, various Li-concentrations of slabs are taken into account with different type of adsorptions. With these proposed models, the surface energies of each facet were calculated. Then the simulated morphology of NCM which is also called Wulff shape was successfully constructed. Based on the exposed planes on the Wulff shape, the adsorption models of ethylene carbonate (EC) and propane sultone (PS) were established. The adsorption process was investigated according to adsorption energy, charge density difference and density of states. The result gives the insight to comprehend the initial reaction at the NCM/electrolyte interface.