Structural Evolution and Formation Mechanism of LiNiO2 During High-Temperature Solid-State Synthesis

Abstract

The processes and mechanisms of LiNiO2 synthesis during the high-temperature solid state method, using Ni(OH)2 precursor and different lithium salts (Li2CO3 and LiOH), were revealed by the thermal (TG–DTA) and structural (X-ray diffraction (XRD)) analyses. Morphology characterization (scanning electron microscopy (SEM)) and the soluble lithium titration are carried out to support the findings. The results show that the synthetic processes of LiNiO2 generally include raw materials' dehydration, oxidation, and combination; also, the existence of lithium salts makes the oxidation of Ni(OH)2 relatively easier. Comparing the two lithium salts involved in the reactions, LiOH will bring about a transition oxide (Ni8O10) and lower the initial reaction temperature for LiNiO2 generation. In addition, a decent temperature under 800 °C, a preheat treatment in 500–600 °C, and a properly longer heating time are suggested to be significant for obtaining the ideal LiNiO2 materials.