Unveiling the crystallographic effect of Li(Ni0.90Co0.09Al0.01)O2 with a high Ni content on high capacity generation in Li-ion batteries

Abstract

Li(Ni_0.90Co_0.09Al_0.01)O₂, with a high Ni content, is an attractive cathode material for Li-ion batteries due to its high capacity generation at 0.1C, achieving 246 mA h g⁻¹ during charging and 225 mA h g⁻¹ during discharging. The crystallographic effect on capacity generation was examined through in situ X-ray diffraction of Li(Ni_0.90Co_0.09Al_0.01)O₂. X-ray diffraction peaks showed distinct alterations in the final stage of charging, depending on the C-rate and temperature. The movement of Li-ions in the material was obstructed under high C-rate or low temperature conditions. The delay in Li-ion mobility was revealed through complementary crystallographic analyses, including X-ray diffraction, extended X-ray absorption fine structure, pair distribution function, and transmission electron microscope. The atomic distances varied distinctly depending on the type of atom during charging and discharging. The strain and size of the crystal in the material changed anisotropically during charging. This anisotropic alteration induced cracks, voids, and atomic distortions within the Li(Ni_0.90Co_0.09Al_0.01)O₂ particles. Our results established the chemo-mechanical behavior associated with capacity generation in Li(Ni_0.90Co_0.09Al_0.01)O₂. Finally, eliminating the anisotropic state within the cathode material was extremely crucial for enhancing the capacity and lifetime of Li-ion batteries.