Measurement of thermal weight loss of lithium hydroxide monohydrate using a synchronous thermal analyzer

With the increasing demand in the new energy materials industry, lithium hydroxide hydrate, as an important intermediate in lithium salt chemical industry, is widely used in industries such as cathode material preparation, coating additives, lubricants, glass ceramics, etc. Its dehydration and decomposition behavior not only affects material purity, but also directly relates to sintering temperature setting, storage process, and composition control. Based on the results of synchronous thermal analysis, this article summarizes the decomposition mechanism and key temperature range of lithium hydroxide monohydrate in an oxygen atmosphere, providing data support for enterprise production and engineering applications.

1、 Operation steps of the experiment

1. Measuring instrument: DZ-STA401 synchronous thermal analyzer

2. Measurement sample: Lithium hydroxide monohydrate

3. Experimental parameters:

Atmosphere: Oxygen

Heating rate: 5 ℃/min

Temperature range: 25 ℃ to 800 ℃

Explanation: The data under oxygen atmosphere is closer to the actual situation of sintering, oxidation baking, etc.

4. Measurement chart

5. Measurement spectrum analysis:

Stage 1: Removal of Crystalline Water

Temperature range: 31.8 ℃ to 130.3 ℃

Weight loss: ≈ 11.31%

Thermal effect: obvious endothermic peak (≈ 90 ℃)

LiOH·H2O→LiOH+H2O↑

Inspiration: Drying temperature greater than 130 ℃ is required to achieve complete dehydration; Long term storage below this temperature is not prone to 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 → Li ₂ O+H ₂ O ↑

Inspiration: The critical decomposition range is from 200 ℃ to 450 ℃. If the sintering temperature of the positive electrode material covers this range, the proportion change caused by water evaporation needs to be considered. If the residence time in this range is too long, it may lead to lithium loss, stoichiometric deviation, and high oxygen content in the product.

Stage 3: High temperature stability

Temperature range: 590.7 ℃ to 744.4 ℃

Weight loss: ≈ 0.32%

Explanation: There is no obvious reaction, and the system tends to stabilize.

2、 Experimental conclusion

A temperature greater than 600 ℃ can be considered as a relatively stable range for Li2O, which is suitable for maintaining the stability of the lithium source structure in subsequent high-temperature stages. This thermal analysis result provides a complete route and key temperature control points for LiOH · H2O → LiOH → Li2O, which is an important reference for material formulation and sintering temperature setting.