With the increasing demand from the new energy materials industry, lithium hydroxide hydrate, as an important intermediate in lithium salt chemistry, is widely used in cathode material preparation, coating additives, lubricants, glass and ceramics industries. Its dehydration and decomposition behavior not only affects material purity but also directly relates to sintering temperature settings, storage processes, and composition control. This paper, based on synchronous thermal analysis results, outlines the decomposition mechanism and key temperature range of lithium hydroxide monohydrate in an oxygen atmosphere, providing data support for enterprise production and engineering applications.
I. Experimental Procedure
1. Measuring Instrument: STA400 Synchronous Thermal Analyzer
2. Sample: Lithium hydroxide monohydrate
3. Experimental Parameters:
Ambient: Oxygen
Heating Rate: 5℃/min
Temperature Range: 25℃ to 800℃
Note: Data under an oxygen atmosphere more closely reflects actual sintering and oxidation processes.
4. Measurement Spectra
5. Measurement Spectrum Analysis:
Stage 1: Removal of Water of Crystallization
Temperature Range: 31.8℃ to 130.3℃
Weight Loss: ≈11.31%
Thermal Effect: Obvious endothermic peak (≈90℃)
LiOH·H2O→LiOH+H2O↑
Implication: Complete dehydration can only be achieved at drying temperatures above 130℃; below this temperature, long-term storage does not easily result in water loss.
Stage 2: Thermal Decomposition of Lithium Hydroxide
Temperature Range: 198.9℃ to 456.4℃
Weight Loss: ≈12.53%
Thermal Effect: Second endothermic peak (≈276℃)
Core Reaction: 2LiOH→Li₂O+H₂O↑
Implication: 200℃ to 450℃ is the critical decomposition range. If the sintering temperature of the cathode material covers this range, the proportion change caused by water evaporation needs to be considered. Excessive residence time in this range may lead to lithium loss, stoichiometric deviations, and high oxygen content in the product.
Stage 3: High-Temperature Stability
Temperature Range: 590.7℃ to 744.4℃
Weight Loss: ≈0.32%
Explanation: No significant reaction; the system tends to stabilize.
II. Experimental Conclusions
Temperatures above 600℃ can be considered a relatively stable range for Li₂O, suitable for maintaining the stability of the lithium source structure in subsequent high-temperature stages. This thermal analysis provides the complete route of LiOH·H₂O→LiOH→Li₂O and the key temperature control points, serving as an important reference for material formulation and sintering temperature setting.
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