Lithium hydroxide
Lithium hydroxide is an inorganic compound with the chemical formula LiOH, existing as a white, hygroscopic, odorless crystalline solid that is highly soluble in water. As an alkali metal hydroxide, it functions as a strong base, readily neutralizing acids and reacting with certain metals to produce hydrogen gas.[1][2] The compound has a molecular weight of 23.95 g/mol, a density of 1.46 g/cm³ (anhydrous), a melting point of 462 °C, and decomposes at around 924 °C without boiling. It exhibits high solubility in water (12.8 g/100 mL at 20 °C) and is moderately soluble in ethanol, but insoluble in ether. Lithium hydroxide is typically available in anhydrous form or as the monohydrate (LiOH·H₂O), which is more stable and commonly used industrially.[1][3] Industrial production of lithium hydroxide primarily involves the reaction of lithium carbonate (Li₂CO₃) with calcium hydroxide (Ca(OH)₂) in an aqueous slurry, producing lithium hydroxide and precipitating calcium carbonate (CaCO₃) for separation. Alternative methods include hydrometallurgical extraction from lithium-rich brines or spodumene ore, often involving sulfuric acid leaching followed by precipitation and purification to achieve battery-grade purity (>99.5%). Emerging direct lithium extraction technologies, such as resin-based or electrochemical processes, are gaining traction to improve efficiency and reduce environmental impact.[4][5] Lithium hydroxide is essential in the production of lithium-ion batteries, serving as a key precursor for synthesizing high-nickel cathode materials like NMC (nickel-manganese-cobalt) and NCA (nickel-cobalt-aluminum), which power electric vehicles and energy storage systems. It is also widely used to manufacture lithium-based greases, which account for a significant portion of its consumption due to their high-temperature stability and water resistance. In environmental control applications, lithium hydroxide acts as an efficient CO₂ absorbent in closed-loop systems, such as those in submarines, spacecraft, and rebreathers, reacting to form lithium carbonate and water. Additional uses include ceramics and glass fluxing agents, alkaline battery electrolytes, photographic developers, and chemical reagents for synthesizing other lithium salts.[6][7][8][9]Properties
Physical properties
Lithium hydroxide exists in both anhydrous and monohydrated forms, with the chemical formula LiOH for the anhydrous compound and LiOH·H₂O for the monohydrate.[1][10] The anhydrous form appears as a white, hygroscopic crystalline solid with a tetragonal crystal structure (space group P4/nmm).[11][12] It has a density of 1.46 g/cm³, a melting point of 462 °C, and decomposes above 924 °C without boiling.[11][3] The compound is odorless and exhibits a refractive index of 1.464, with a specific heat capacity of 2.071 J/g·K.[13][11][14] Lithium hydroxide is highly soluble in water, with a solubility of 12.8 g/100 mL at 20 °C, slightly soluble in ethanol at approximately 1.5 g/100 mL, and insoluble in ether.[11][1][3] Due to its hygroscopic nature, the anhydrous form readily absorbs moisture from the air, forming the monohydrate.[1] The monohydrate form is also a white, odorless, hygroscopic crystalline solid with a density of 1.51 g/cm³.[10] It loses its water of hydration upon heating to around 100 °C and has a refractive index of 1.460.[15][16] Its solubility in water is higher than the anhydrous form, at 19.1 g/100 mL at 20 °C.[10]Chemical properties
Lithium hydroxide (LiOH) is an ionic compound composed of lithium cations (Li⁺) and hydroxide anions (OH⁻), adopting a crystal structure in the P4/nmm space group. In aqueous solutions, it fully dissociates into Li⁺ and OH⁻ ions, acting as a strong electrolyte and strong base.[1][17] Among the alkali metal hydroxides, LiOH exhibits the weakest basicity, attributed to the small ionic radius of Li⁺, which introduces partial covalent character and slightly reduces its ionicity compared to NaOH or KOH. Despite this, it remains a strong base capable of exothermic neutralization with acids, producing salts and water. Its basic strength follows the order LiOH < NaOH < KOH < RbOH < CsOH, reflecting the increasing ionic nature down the group.[18] LiOH dissolves exothermically in water to form alkaline solutions and readily absorbs atmospheric CO₂, converting to lithium carbonate via the reaction: $2 \mathrm{LiOH} + \mathrm{CO_2} \rightarrow \mathrm{Li_2CO_3} + \mathrm{H_2O} [19] Upon thermal decomposition above 924 °C, it yields lithium oxide and water: $2 \mathrm{LiOH} \rightarrow \mathrm{Li_2O} + \mathrm{H_2O} [1] The Li⁺ cation maintains stability in the +1 oxidation state with no tendency for redox change under standard conditions, whereas the OH⁻ anion can participate in oxidation reactions, such as anodic processes in electrolysis. Lithium oxide (Li₂O) functions as the conjugate base, reacting with water to regenerate LiOH, while water (H₂O) is the conjugate acid of OH⁻ in solution.[1][20]History
Discovery
Lithium was discovered in 1817 by Swedish chemist Johan August Arfwedson while analyzing the mineral petalite (LiAlSi₄O₁₀) from a mine on the island of Utö in Sweden.[21] Working in the laboratory of Jöns Jacob Berzelius, Arfwedson identified an unknown alkali in the ore through chemical analysis, noting that it behaved similarly to sodium and potassium but was distinct, with petalite containing approximately 8-9% of this new substance.[22] Berzelius confirmed the findings, and the element was named lithium from the Greek word "lithos," meaning stone, reflecting its origin in minerals rather than plants or animals like the other alkali metals.[21] This discovery occurred amid broader 19th-century studies of alkali metals, following Humphry Davy's electrolytic isolation of sodium and potassium a decade earlier. Arfwedson extended his analysis to other minerals, detecting lithium in spodumene and lepidolite, establishing it as a component of various silicate ores.[22] These findings were published in 1818 in the Swedish journal Afhandlingar i Fysik, Kemi och Mineralogi, with Berzelius announcing the discovery internationally in the Journal für Chemie und Physik.[21] Although Arfwedson prepared several lithium salts, including the carbonate and sulfate, he could not isolate the pure metal due to limitations in electrolytic techniques at the time.[23] The isolation of lithium metal was achieved in 1818 by Humphry Davy and William Thomas Brande through the electrolysis of lithium oxide (Li₂O), using a more powerful battery than what was available to Arfwedson.[24] In the early 19th century, lithium hydroxide (LiOH) was first prepared by reacting lithium carbonate with slaked lime (Ca(OH)₂) or by the reaction of the newly isolated lithium metal with water, yielding the soluble hydroxide that confirmed lithium's classification as an alkali metal, distinct from alkaline earth metals whose hydroxides are less soluble. This preparation highlighted LiOH's high solubility in water, a key property shared with other alkali hydroxides, aiding in its identification and study during the initial characterization of lithium compounds.[25]Commercial development
Lithium hydroxide's commercial development began in the early 20th century, transitioning from a laboratory curiosity to an industrial staple primarily through its application in lubrication technologies. In the 1940s, lithium grease, produced by reacting lithium hydroxide with fatty acids, emerged as a superior lubricant due to its stability across wide temperature ranges.[26] This innovation was patented in 1942 by Clarence Earle, marking the first widespread use of simple lithium soap thickeners in greases.[27] During World War II, the U.S. military adopted lithium hydroxide-based greases for high-temperature applications in aircraft engines, leveraging their performance in extreme conditions to support wartime aviation needs.[28] By the 1960s, lithium hydroxide found critical application in space exploration, particularly for carbon dioxide scrubbing systems. NASA selected it for the Apollo missions owing to its efficient absorption of CO₂ from cabin air, where canisters filled with lithium hydroxide cartridges maintained breathable atmospheres during extended flights.[29] This adoption highlighted the compound's reliability in closed-loop environments, as demonstrated during the Apollo 13 mission when improvised lithium hydroxide setups from the lunar module were adapted to sustain the crew.[30] The 1970s marked a pivotal shift toward electrochemical applications, with M. Stanley Whittingham's research at Exxon pioneering lithium intercalation cathodes using titanium disulfide and other lithium compounds, laying the groundwork for rechargeable batteries.[31] This work influenced subsequent developments in the 1980s, where John Goodenough identified lithium cobalt oxide (LiCoO₂) as a high-voltage cathode material, and Akira Yoshino developed prototypes with carbon anodes.[32] Lithium hydroxide served as a key precursor in synthesizing these LiCoO₂ cathodes through reactions with cobalt compounds, enabling the stable intercalation of lithium ions essential for prototype viability.[33] Commercial scaling accelerated in the 1990s alongside the rise of portable electronics. Sony commercialized the first lithium-ion batteries in 1991, incorporating LiCoO₂ cathodes derived from lithium hydroxide, which powered devices like camcorders and laptops with unprecedented energy density.[34] This breakthrough tied lithium hydroxide's growth to consumer technology, as its role in cathode production became integral to battery manufacturing.[35] The 2010s witnessed an explosive demand surge driven by electric vehicles (EVs), propelling lithium hydroxide production to meet the need for high-nickel cathodes. Global capacity expanded from approximately 130,000 metric tons in 2020 to over 500,000 metric tons as of 2025, with EVs accounting for about 35% of lithium demand in 2020, rising to over 70% by the mid-2020s.[36][37] This boom, amid 2022-2024 supply oversupply and price volatility, underscored lithium hydroxide's centrality in enabling high-performance batteries for sustainable transportation.[38]Production
Lithium carbonate route
The lithium carbonate route for producing lithium hydroxide begins with lithium carbonate (Li₂CO₃). The lithium carbonate feedstock can be derived from either spodumene ore processing or lithium-rich brines. For spodumene ore (LiAlSi₂O₆), a primary hard-rock lithium source, the concentrate is first calcined at temperatures exceeding 1000 °C, typically 1050–1100 °C, to convert the stable α-phase to the more reactive β-phase, enabling subsequent acid leaching with sulfuric acid to extract lithium as a sulfate solution. This solution is then treated with sodium carbonate to precipitate high-purity Li₂CO₃, which serves as the feedstock for the metathesis reaction.[39][40][41] The core process involves reacting aqueous slurries of Li₂CO₃ and calcium hydroxide (Ca(OH)₂, or hydrated lime) at 80–100 °C, where lithium ions exchange with calcium ions in a metathesis reaction: \text{Li}_2\text{CO}_3 + \text{Ca(OH)}_2 \rightarrow 2 \text{LiOH} + \text{CaCO}_3 \downarrow This step produces a lithium hydroxide solution with concentrations up to 3.5% LiOH and a calcium carbonate precipitate, which is filtered out for removal. The reaction is driven by the low solubility of CaCO₃, facilitating separation.[42][43][4] Following filtration, the LiOH solution undergoes purification to achieve battery-grade quality, typically via ion exchange to remove residual impurities such as calcium, magnesium, and sodium, or recrystallization to further enhance purity. The purified solution is then concentrated and crystallized as lithium hydroxide monohydrate (LiOH·H₂O). This route yields approximately 95–96% lithium recovery overall, with product purity exceeding 99.5%.[4][44][45] Key advantages include the production of high-purity LiOH suitable for lithium-ion battery cathodes and the recyclability of the CaCO₃ by-product, which can be repurposed in lime production or construction materials. However, the process is energy-intensive, primarily due to the high-temperature calcination of spodumene required upstream. This route is widely implemented at scale.[46][43]Lithium sulfate route
The lithium sulfate route for lithium hydroxide production utilizes lithium sulfate (Li₂SO₄) as the key intermediate, derived from the sulfuric acid processing of spodumene ore. Spodumene concentrate, primarily in its α-phase, is roasted at 1000–1100 °C to form the more reactive β-spodumene phase, which facilitates subsequent leaching.[47] The β-spodumene is then roasted with concentrated sulfuric acid at around 250 °C, followed by water leaching to solubilize lithium as Li₂SO₄, while silica and other gangue remain as insoluble residue.[48] Excess sulfuric acid in the leachate is neutralized with lime (Ca(OH)₂), generating gypsum (CaSO₄·2H₂O) as a by-product, which is commonly repurposed in construction applications such as cement and plasterboard production.[49][50] The purified Li₂SO₄ solution undergoes alkaline conversion by reaction with sodium hydroxide (NaOH) at 90–100 °C, following the metathesis equation: \ce{Li2SO4 + 2 NaOH -> 2 LiOH + Na2SO4} [51][52] This step produces a mixed solution of lithium hydroxide and sodium sulfate, with the latter exhibiting higher solubility at elevated temperatures than at lower temperatures. Upon completion of the reaction, the solution is cooled to 20–30 °C to selectively crystallize and precipitate Na₂SO₄ due to its reduced solubility, which is separated via filtration or centrifugation for recovery as a marketable by-product.[48] The filtrate, enriched in LiOH, is then concentrated through evaporation under vacuum, followed by cooling to induce crystallization of lithium hydroxide monohydrate (LiOH·H₂O). The crystals are separated, washed, and dried to achieve battery-grade purity.[48] Prior to the NaOH reaction, impurities such as calcium, magnesium, and residual sulfate in the Li₂SO₄ solution are removed through precipitation, often employing soda ash (Na₂CO₃) to form insoluble carbonates that can be filtered out.[53] This purification ensures high-purity output, with overall lithium recovery yields typically ranging from 90% to 95%.[54] Compared to the lithium carbonate route, the sulfate process requires fewer intermediate steps and lower overall energy input, enhancing its scalability for high-volume manufacturing.[41] It is widely adopted by Chinese producers, including Ganfeng Lithium, which routinely converts lithium sulfate intermediates to hydroxide in its integrated operations.[55]Commercial production and market
Major producers
Ganfeng Lithium, a leading Chinese producer, operates with an annual lithium hydroxide capacity of approximately 85,000 metric tons by 2025, supported by expansions in Australia including joint ventures at the Mount Marion mine.[56] Albemarle Corporation, headquartered in the United States, maintains a significant capacity of around 50,000 metric tons per year, primarily through its Kemerton plant in Australia and U.S. facilities converting hard-rock spodumene to battery-grade hydroxide.[57] Sociedad Química y Minera de Chile (SQM), based in Chile, produces about 20,000 metric tons annually from brine sources and is expanding hydroxide output to 100,000 metric tons by the end of 2025.[58] Other notable producers include Tianqi Lithium, another Chinese giant with a capacity of roughly 60,000 metric tons per year, leveraging stakes in Australia's Greenbushes mine and the Kwinana refinery.[59] Arcadium Lithium (acquired by Rio Tinto in March 2025; formed from the merger of Livent and Allkem), with operations in Argentina, the U.S., and China, held a combined capacity of approximately 30,000 metric tons annually for high-purity lithium hydroxide prior to the acquisition.[59] Piedmont Lithium in the U.S. planned to commence production in 2025 at its Carolina Lithium project but has delayed startup due to permitting and market conditions, targeting battery-grade material in the future.[60]| Producer | Location/Base | Approximate Capacity (kt/year, 2025) | Key Facilities/Notes |
|---|---|---|---|
| Ganfeng Lithium | China/Australia | 85 | Expansions via Mount Marion; battery-grade focus |
| Albemarle | USA/Australia | 50 | Kemerton plant; hard-rock conversion |
| SQM | Chile | 20 (expanding to 100 hydroxide) | Brine-based, expanding hydroxide production |
| Tianqi Lithium | China/Australia | 60 | Greenbushes and Kwinana refinery |
| Arcadium Lithium (acquired by Rio Tinto, March 2025) | Argentina/USA/China | 30 | Merged operations for high-purity; now under Rio Tinto |
| Piedmont Lithium | USA | Delayed (originally planned startup 2025) | Carolina project for battery-grade; permitting ongoing |
Supply and demand trends
The global supply of lithium hydroxide experienced significant oversupply pressures in 2023 and 2024, prompting major producers to idle capacity and reduce output to stabilize prices amid slower-than-expected demand growth. For instance, Albemarle Corporation curtailed its expansion plans and cut capital spending by 65% for 2025, from $1.7 billion in 2024 to approximately $600 million, as announced in November 2025, in response to weak market conditions that led to a 39% drop in net sales during the second quarter of 2024.[63][64] By 2025, supply dynamics began to recover with the commissioning of new projects in Australia and Indonesia, contributing an estimated additional 50,000 metric tons of lithium hydroxide capacity annually, though some initiatives faced delays or terminations due to ongoing market volatility. As of November 2025, lithium prices have risen about 18% in the past month, signaling recovery, with SQM confirming in its Q3 earnings its expansion to 100,000 metric tons of lithium hydroxide by year-end.[65] Australia's dominance in hard-rock lithium mining supported expansions like the Kwinana refinery joint venture, which aimed to increase output to 9,000–11,000 tons in 2025–2026, while Indonesia's brine-based developments advanced through partnerships to bolster regional processing.[66][67] However, bottlenecks persisted in refining operations compared to upstream mining, as conversion facilities struggled to keep pace with spodumene concentrate availability, leading to export imbalances.[38] Demand for lithium hydroxide is predominantly driven by its use in lithium-ion batteries, accounting for approximately 80% of global consumption in 2025, fueled by the rapid expansion of electric vehicles (EVs). The remaining demand stems from applications in lubricants, greases, and carbon dioxide scrubbing systems, which provide more stable but smaller-volume outlets.[68][69] Global lithium hydroxide output reached about 250,000 metric tons in 2025, reflecting growth aligned with overall lithium production increasing 18% year-over-year to 240,000 tons of lithium content in 2024, with hydroxide forms gaining share due to battery-grade preferences.[70][59] Geopolitical factors have reshaped supply chains, with the U.S. Inflation Reduction Act (IRA) incentivizing domestic production through tax credits and investments totaling nearly $100 billion in battery supply infrastructure since 2022, aiming to reduce reliance on foreign sources and boost U.S. lithium hydroxide refining capacity. In parallel, China implemented new export controls on lithium-ion battery technologies and materials effective November 8, 2025, targeting equipment and graphite anodes to protect domestic innovation, though temporary suspensions on certain minerals were announced on November 9, 2025, to ease global tensions through November 27, 2026.[71][72][73] Looking ahead, demand for lithium hydroxide is projected to reach 700,000 metric tons by 2030, driven by EV and energy storage growth at a CAGR exceeding 15%, while recycling is emerging as a supplementary supply source, expected to contribute about 5% of total lithium needs by 2025 through improved recovery of battery materials.[74][69][75]Applications
Lithium-ion batteries
Lithium hydroxide monohydrate (LiOH·H₂O) serves as a critical lithium source in the synthesis of cathode active materials for lithium-ion batteries, particularly nickel-manganese-cobalt (NMC) layered oxides. In the co-precipitation process, transition metal precursors such as nickel, cobalt, and manganese sulfates are first reacted with sodium hydroxide to form a hydroxide precursor, NixMnyCoz(OH)2, where x + y + z = 1. This precursor is then intimately mixed with high-purity LiOH·H₂O in a stoichiometric ratio (typically with 3-5% excess lithium to account for volatilization) and calcined at temperatures between 700-950°C under oxygen flow to yield the final cathode material, LiNixMnyCozO2. A simplified representation of the lithiation step for a nickel-rich variant, such as lithium nickel oxide, is given by the equation: \text{Ni(OH)}_2 + \text{LiOH} \rightarrow \text{LiNiO}_2 + 2\text{H}_2\text{O} This process ensures uniform lithium incorporation and minimizes impurities that could degrade battery performance.[76][77] High-purity LiOH·H₂O (battery-grade, >99.5% purity) is preferred over lithium carbonate (Li₂CO₃) for synthesizing high-nickel NMC cathodes like NMC811 (LiNi0.8Mn0.1Co0.1O2), as it decomposes more cleanly during calcination, avoiding CO₂ release that occurs with Li₂CO₃ and reduces residual lithium impurities on the cathode surface. This preference stems from lower greenhouse gas emissions in the cathode production stage; for NMC811, using LiOH·H₂O can result in up to 20% lower CO₂-equivalent emissions compared to Li₂CO₃, depending on the upstream production route (brine vs. ore). High-nickel cathodes enabled by LiOH·H₂O offer superior volumetric energy density (up to 700 Wh/L) compared to lithium iron phosphate (LFP) cathodes (around 400 Wh/L), making them ideal for electric vehicles (EVs) requiring extended range.[78][79][80] In 2025, approximately 70% of global lithium hydroxide consumption is driven by lithium-ion battery production, primarily for EV applications. This demand supports annual battery manufacturing exceeding 1,900 GWh worldwide, with NMC cathodes accounting for a significant share in high-performance packs. Recycling processes further enhance sustainability; hydrometallurgical methods can recover over 90% of lithium from spent batteries as LiOH·H₂O with >99% purity, enabling its reuse in new cathode synthesis and closing the materials loop.[81][82][83]Lubricants and greases
Lithium hydroxide serves as a key reagent in the production of high-performance lubricating greases, primarily through its reaction with 12-hydroxystearic acid to form lithium 12-hydroxystearate soap, which acts as the thickener. The saponification reaction proceeds as follows:\ce{LiOH + HOOC-(CH2)_{10}-CH(OH)-(CH2)_{10}-CH3 -> LiOOC-(CH2)_{10}-CH(OH)-(CH2)_{10}-CH3 + H2O}
This process typically involves heating the reactants in the presence of base oil to facilitate soap formation and dispersion, yielding a semi-solid grease structure.[84] The resulting lithium 12-hydroxystearate imparts desirable properties to the grease, including excellent water resistance that prevents washout under wet conditions and thermal stability allowing operation up to 200 °C, with a typical drop point of approximately 190 °C. These characteristics make lithium-based greases suitable for demanding environments where mechanical stability and protection against corrosion are essential. Compared to traditional calcium or sodium soaps, lithium soaps provide superior thermal resistance, broader temperature range compatibility, and better shear stability, enabling their use as versatile multi-purpose lubricants.[85][86] Lithium hydroxide-based greases are predominantly applied in automotive and industrial settings, such as wheel bearings, chassis components, and heavy machinery, often formulated to NLGI grade 2 consistency for general-purpose lubrication. They account for about 70% of global grease production and represent less than 10% of total lithium hydroxide consumption, with an estimated annual market of around 20 kt for this application. Despite a gradual shift toward lithium complex soaps and non-lithium alternatives like calcium sulfonate complexes—driven by supply concerns and enhanced performance needs in extreme conditions—simple and complex lithium-based greases remain dominant in 2025 due to their proven reliability and cost-effectiveness.[85][87]