Lithium hydroxide (LiOH, CAS 1310-65-2) is an inorganic compound obtained mainly by reacting lithium carbonate with calcium hydroxide. It is a strong base that appears as a white crystalline solid and is produced in anhydrous and monohydrate forms. Lithium hydroxide is best known as a precursor for the lithium hydroxide used in battery cathode materials and as the raw material for lithium stearate greases, but it also serves in carbon dioxide absorption, ceramics, and pH control. This article covers its identity, physical properties, main applications, and handling considerations.
What Is Lithium Hydroxide?
Lithium hydroxide is the hydroxide salt of lithium, with the formula LiOH. Industrially, it is produced by metathesis of lithium carbonate with calcium hydroxide, or by electrolysis of lithium chloride solutions. The commercial product is often the monohydrate LiOH-H2O, which can be dehydrated to the anhydrous form. Because lithium hydroxide is a strong base, it reacts readily with acids, acidic gases, and fatty acids, which is the basis for several of its industrial uses. It is supplied in grades ranging from technical material for grease production to battery-grade material with tightly controlled impurity limits.
Physical and Chemical Properties
| Property | Value |
|---|---|
| CAS number | 1310-65-2 |
| Chemical formula | LiOH |
| Molecular weight | 23.95 g/mol |
| Density | About 1.46 g/cm3 |
| Melting point | About 462 °C |
| Boiling point | About 924 °C |
| Solubility | Soluble in water, slightly soluble in ethanol |
| Appearance | White crystalline solid |
Major Applications of Lithium Hydroxide
Battery materials: a key precursor for nickel-rich cathode materials such as NMC and NCA used in lithium-ion batteries.
Lubricating greases: reacts with stearic and other fatty acids to form lithium soaps, the base of high-performance multi-purpose greases.
Carbon dioxide scrubbing: absorbs CO2 in closed environments such as spacecraft, submarines, and breathing apparatus.
Ceramics and glass: lowers melting temperature and improves properties in specialty ceramic and glass formulations.
pH control and water treatment: neutralizes acids and adjusts alkalinity in process streams.
Chemical synthesis: a source of lithium ions for the production of other lithium salts and organic lithium compounds.
Lithium Hydroxide Monohydrate vs Anhydrous
The monohydrate form, LiOH-H2O, is the most common commercial grade and is easier to handle because it is less dusty and more stable in storage. The anhydrous form, LiOH, has a higher lithium content per unit mass and is preferred where water introduction must be minimized, such as in certain battery and specialty chemical processes. Specification sheets state the assay, water content, and impurity profile for each grade, and buyers should match the grade to the application requirement rather than treating the two forms as interchangeable.
Safety and Handling Considerations
Lithium hydroxide is corrosive. It can cause severe skin burns, eye damage, and respiratory irritation if inhaled as dust or mist, so wear protective gloves, goggles, and respiratory protection when handling powder. Work in ventilated areas and avoid generating dust. Lithium hydroxide absorbs moisture and carbon dioxide from the air, so store it in tightly sealed containers in a dry area, away from acids and water-reactive materials. In case of skin or eye contact, rinse thoroughly with water and seek medical attention. Refer to the safety data sheet for the specific grade before use.
Frequently Asked Questions
What is the CAS number for lithium hydroxide?
The CAS number for anhydrous lithium hydroxide is 1310-65-2. The monohydrate form, LiOH-H2O, has its own CAS number and should be identified separately when ordering.
Is lithium hydroxide the same as lithium carbonate?
No. Lithium hydroxide (LiOH) is a strong base, while lithium carbonate (Li2CO3) is a salt of carbonic acid. They are different compounds with different properties, and lithium hydroxide is often produced from lithium carbonate.
What is lithium hydroxide used for in batteries?
Lithium hydroxide is used to produce high-nickel cathode materials such as NMC and NCA, which improve the energy density and performance of lithium-ion batteries for electric vehicles and energy storage.
Is lithium hydroxide dangerous?
Lithium hydroxide is corrosive and can burn skin, eyes, and respiratory tissues. With proper PPE, ventilation, and handling procedures, it can be used safely in industrial processes.
What is the difference between LiOH and LiOH-H2O?
LiOH is anhydrous lithium hydroxide, while LiOH-H2O is the monohydrate containing one molecule of water of crystallization. The monohydrate is the more common commercial form and is easier to handle.
How is lithium hydroxide produced?
Lithium hydroxide is commonly produced by reacting lithium carbonate with calcium hydroxide, or by electrolysis of lithium chloride solutions. The product is crystallized, purified, and dried to the required grade.
