Thermal behavior of Li1-xNiO2 (R3̄m or C2/m) up to 400°C was studied using thermogravimetry (TG), differential scanning calorimetry (DSC), and high-temperature X-ray diffraction measurements and its decomposition mechanism was proposed. Delithiated Li1-xNiO2 was thermally decomposed to LiNi2O4 spinel (Fd3m) at the temperature range of 180-250°C. For x ≤ 0.5, Li1-xNiO2 was decomposed to LiNiO2 and LiNi2O4 and the fraction of the spinel in the decomposed product increased almost linearly with x. For 0.5 < x ≤ 0.8, Li1-xNiO2 was converted into LiNi2O4 spinel and this reaction was accompanied by oxygen evolution. Li1-xNiO2 of all compositions turned into a rock-salt phase (Fm3m) with oxygen liberation at temperatures above 270°C. The temperature for the decomposition of Li1-xNiO2 to a spinel or a rock-salt phase decreased with x in Li1-xNiO2. The thermal behavior of Li1-xNiO2 could be interpreted as an overlap of the exothermic rearrangement of cations (nickel and lithium ions) to form a spinel or a rock-salt phase and the endothermic oxygen evolution reaction.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Energy Engineering and Power Technology
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering