Ni-stabilizing additives for completion of Ni-rich layered cathode systems in lithium-ion batteries: An Ab initio study

Abstract

We propose the development of Ni-stabilizing electrolyte additives to fundamentally prevent the degradation of Ni-rich layered cathode systems in lithium-ion batteries because unstable surface Ni and the dissolved Ni2+ are the major problems of those systems. The Ni2+-affinity is investigated as a key factor of the Ni-stabilizing additives. However, when providing a noble function to the electrolyte additive, the redox stability of the additives should be also understood. Thus, in addition to the intrinsic oxidation energy, the protonation and dehydrogenation energies of the additive molecules are calculated to determine the H-transfer-driven electrolyte oxidation. The Li+-complexation is considered to model the electrolyte reduction. We investigate the molecular-leveled computed factors of electrolyte materials using fully automated high-throughput ab initio calculations. Those computed factors for representative molecules based on CO3, SO4, SO3, SO2, PC3, PO3, and OPO3, which are of great interest as major parts of electrolyte materials, are discussed to guide the additive development. In particular, SO2 and OPO3 molecules, which can strongly stabilize Ni2+ in a structurally stable form, have great advantages as Ni-stabilizing electrolyte additives for completion of Ni-rich layered cathode systems.