by Composition and Properties
LiOH is an inorganic compound composed of lithium and hydroxide ions. It exists as white hygroscopic crystals or as a white crystalline powder. LiOH has a molecular formula of LiOH and a molar mass of 23.95 g/mol. It is highly soluble in water, ethanol, and methanol but insoluble in acetone, diethyl ether and other organic solvents. LiOH has a high melting point of 523°C and decomposes at higher temperatures to form lithium oxide.
The Lithium Hydroxide compound is formed when lithium metal reacts violently with water according to the reaction:
2Li + 2H2O → 2LiOH + H2
It also reacts vigorously with acids like hydrochloric acid (HCl) to form lithium chloride (LiCl) and water.
LiOH + HCl → LiCl + H2O
Its aqueous solution is strongly alkaline with a pH of around 13. The hydroxide ion gives LiOH its basic character.
Manufacturing
The commercial production of LiOH primarily involves two main methods – electrolysis of lithium chloride and reaction of lithium metal with water vapor.
In the electrolysis method, a concentrated solution of lithium chloride is electrolyzed between carbon anodes and stainless steel cathodes. Lithium ions migrate to the cathode where they react with hydroxide ions and water to form a Lithium Hydroxide precipitate.
2LiCl + 2H2O → 2LiOH + H2 + Cl2
In the vapor-phase process, high purity lithium metal granules are heated in a special reactor along with regulated amounts of steam or water vapor. The exothermic reaction between lithium and water vapor produces LiOH powder.
2Li + 2H2O → 2LiOH + H2
The powder is then separated, washed, filtered and dried. Both these processes are scalable for large scale production. The end product purity depends on the manufacturing route and subsequent purification steps.
Battery Electrolyte
One of the major uses of Lithium Hydroxide is in lithium-ion battery electrolytes. An aqueous solution of LiOH is used to convert a battery separator material like porous polyolefin into its hydroxide form. This increases the separator’s ability to conduct hydroxide ions which are involved in the battery’s electrochemical reactions.
Preparing the separator in this way enhances its wettability when in contact with the non-aqueous electrolyte inside a lithium-ion battery. This leads to better ionic conductivity and improved battery performance over multiple charge-discharge cycles. The LiOH treatment makes the separator more compatible for use in high energy density lithium battery technologies.
pH Regulation
Due to its strong basic character, Lithium Hydroxide finds application as a pH regulator and buffering agent. It is used to raise and maintain the pH of various solutions, materials and processes where a highly alkaline environment is required.
Some common uses of LiOH in pH regulation include:
– Water treatment – Added to adjust pH in water softening, municipal water treatment plants.
– Soap and detergent manufacture – Acts as pH adjuster and general purpose additive.
– Metallurgy – Controls pH during metal cleaning, pickling, electroplating and anodizing baths.
– Concrete admixtures – Raises pH of concrete to enhance setting and strength.
– Paper and pulp industry – Maintains pH for bleaching, dyeing, sizing agents in papermaking.
– Bioscience research – Creates stable alkaline conditions for cell culturing, biochemical analysis.
Grease Manufacture
Lithium Hydroxide has an important role to play in soap and lubricating grease manufacturing as well. During production of cast aluminum-complex greases, LiOH is first reacted with fatty acids to form a lithium soap. This lithium soap is then blended with a thickener to create the final grease formulation.
The presence of lithium cations from LiOH endows the grease with desirable properties like reduced oil bleeding, enhanced lubricating performance at high temperatures and improved corrosion protection. Greases containing lithium soap are suitable for heavy-duty applications in various industries. Their stability makes them popular choices as chassis and constant velocity joint greases in automotive and off-highway equipment.
Other Applications
Besides above major uses, Lithium Hydroxide finds application in several other areas due to its strong basic properties:
– Flux for welding – Improves wettability of the flux on the metal surfaces to be joined.
– Ceramics – Acts as sintering aid and pH regulator for production of specialty ceramics and glasses.
– Medicinal products – Used as pharmaceutical excipient and antacid due to ease of handling and stability.
– Air and gas purification – Absorbs carbon dioxide and removes acids from industrial emissions and air.
Conclusion
In summary, Lithium Hydroxide is a technologically important inorganic compound with widespread industrial applications stemming from its basic character, solubility, durability and favorable electrochemical properties. Its key roles in batteries, pH regulation, soap manufacture and other areas have helped establish LiOH as a valuable chemical commodity. Ongoing advancements in battery and energy storage technologies are likely to further boost demand for this
“*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it”
