Ni-rich cathode materials enabled by cracked-surface protection strategy for high-energy lithium batteries

Abstract

The fabrication of high-density electrodes for practical Li-ion batteries requires a high calendaring pressure. However, inevitable cathode particle fracturing increases the cathode–electrolyte contact area, thereby inducing undesirable side reactions that deteriorate battery performance and safety. To resolve this issue, we propose an intergranular protection strategy that can mitigate the crack-induced performance deterioration of Ni-rich cathodes. Our approach is primarily based on microstructure engineering. The introduction of fast interdiffusion pathways for F infusion enables the formation of F-rich species on the surfaces of internal grains. In addition, some F⁻ is doped into the cathode crystal structure, promoting the formation of a structurally stable cation-ordered phase. The chemical and structural engineering of Li[Ni_0.9Co_0.05Mn_0.05]O₂ protects the cracked surfaces from electrolyte attack and thus improves the electrochemical performance of the cathode. The proposed strategy can also reduce the gassing of Ni-rich cathodes. As the incorporation of only trace amounts of Mo and F plays a crucial role in battery performance, this approach is promising for the development of advanced Ni-rich cathodes for future Li-ion batteries.