Three scientists won the 2019 Nobel Prize in chemistry for developing lithium-ion batteries, whose development has helped power the burgeoning electric car industry worldwide. The work of John Goodenough, M. Stanley Whittingham, and Akira Yoshino during the 1970s and 1980s led to lightweight rechargeable batteries that now power smartphones, laptops, cameras, power tools and even help store energy from solar arrays on the International Space Station. Lithium-ion batteries have been touted as a way to lessen the impact of climate change, reducing humanity’s reliance on fossil fuels by storing electricity generated during solar and wind energy peaks to allow for later use.
How an Oil Embargo Helped Innovate the Lithium-Ion Battery
It began in October 1973 during the OPEC oil embargo, when Dr. Whittingham looked into improving ways to store energy from renewable sources to curb humanity’s reliance on fossil fuels. He understood that lithium makes a good anode (the negative charge), releasing electrons easily, but needed a cathode (the positive charge) to capture lithium-ions.
In his search, Whittingham found titanium disulfide acted as a good cathode, and so made the first functioning lithium battery, which was lightweight, required little maintenance, and stored five times more energy than the best nickel-cadmium batteries of the time. Yet the new battery had one drawback when charged too many times; it short-circuited and sometimes even exploded. Dr. Goodenough thought the cathode could be made from a different material, noting that cobalt oxide had a similar structure to titanium disulfide.
Testing showed cobalt oxide tolerated lithium ions being pushed through and pulled out repeatedly from it. This doubled the power of the battery, which could now generate four volts. Dr. Yoshino built on Goodenough’s work, showing how more complex, carbon-based electrodes could also house lithium ions. This meant pure lithium was no longer necessary, just lithium ions, which made the battery safer.
These developments allowed the lithium-ion battery to come into commercial production in 1991, first manufactured by Sony. The battery’s compactness and reliability began to make it essential to many electronic devices that previously used disposable batteries, including gaming devices, radios, laptops and eventually smartphones and other smart devices. Lithium-ion battery technology now also resolves the key objection to the widespread use of solar power: storing energy.
How is Lithium Extracted?
Extracting lithium commercially occurs primarily via two methods. The most common method involves bringing lithium-rich brine deposits from underground reservoirs before separating it. The other involves mining it from ore deposits containing the metal.
How is Lithium Extracted from Brine?
The vast majority of lithium used commercially comes from reservoirs of liquid brine under salt flats known as salars. Lithium-rich brine deposits also occur in brines found near geothermal vents and oil fields. Recovering lithium from these brines requires pumping the brine from these salars into evaporation ponds on the surface, where it takes several months, or even years, for the water to evaporate. Once most of the water has evaporated, it contains high concentrations not just of lithium, but of potassium, sodium, and other minerals as well. These other metals are often extracted while waiting for the lithium to reach a concentration where it can be economically processed, sometimes using reverse osmosis to speed up evaporation. Once it reaches the ideal lithium concentration, it is then pumped to a lithium recovery facility.
The actual process depends on the brine’s composition but will typically go through these stages:
- Pretreatment involves filtering or ion exchange purification, though sometimes uses both processes to remove contaminants from the brine.
- Chemical treatment with solvents and reagents then helps isolate the desired lithium and other minerals through precipitation.
- Filtration then separates these precipitated solids from the brine.
- Commercial lithium production requires a final treatment with a reagent, such as lithium carbonate or sodium carbonate, after which the product is again filtered and dried. This stage may include applying different reagents to produce solid forms of lithium like butyl lithium, lithium bromide, lithium chloride, or lithium hydroxide.
After extracting the lithium, the leftover brine is returned to the underground reservoir.
How is Lithium Extracted via Mining?
Mining lithium from mineral ores only accounts for about 20 tons of lithium per year, and these mineral deposits often contain richer lithium deposits than the salar brines. Even so, it requires more energy and costs more to extract, as these deposits are mined from hard rock. Though over a hundred minerals contain lithium, only five are mined actively for the metal.
These minerals include:
- Spodumene (most common)
The recovery process varies based upon the type of mineral deposit. Generally, it entails removing the minerals from the earth before heating and pulverizing them. The crushed mineral powder is then combined with chemical reactants like sulfuric acid before it is again heated, filtered, and further concentrated. It then goes through an evaporation process to produce lithium carbonate, after which the wastewater is treated for disposal or reuse.
Currently, research is being done to develop sources of lithium found in clay in Nevada. The processes being tested involve leaching the clay with acid, alkaline, chloride, and sulfate, along with segregating minerals with water or applying a hydrothermal treatment. Though none of these have proven economically viable yet, processing lithium from clay may prove an additional source for the metal.
How is Lithium Extracted Sustainably?
Conventional techniques for extracting lithium are far from environmentally friendly. Lithium extraction results in 15 tons of carbon dioxide for every ton of lithium produced. Open pits from mining leave scars on the landscape and require large amounts of water. Extraction from underground reservoirs uses even more water. However, extracting lithium from geothermal springs leaves a comparatively much smaller environmental footprint, including low carbon emissions. Technological advancements in extraction, along with new means of exploration, have made this possible. Additionally, a new technique for extracting lithium from seawater can also be used for brines, which would reduce water use. These newer methods, some of which are close to being perfected, are the last stumbling blocks for the widespread use of storage that will enable renewable energy to realize Dr. Whittingham’s vision for curbing humanity’s use of fossil fuel fuels.
How is Lithium Extracted from Seawater?
It is estimated that hundreds of billions of tons of lithium exist in the Earth’s oceans. Naturally, this makes extracting lithium from seawater an appealing means by which to meet increasing demand for the metal in the future. It has been successfully achieved through a variety of tested processes, though of particular interest are the newer technologies that use membranes, as they lower the cost of extracting lithium from seawater.
Though the world’s oceans contain an estimated 5-thousand times more lithium than that found on the land, these concentrations are extremely low, occurring at .2 parts per million (ppm). Capturing the metal required a new approach to make extraction economically viable. A new method using an electrochemical cell that contains a ceramic membrane made from lithium lanthanum titanium oxide (LLTO) has solved this problem. The ceramic membrane’s crystalline structure has holes that are just wide enough for lithium ions to pass through while also blocking larger ions from other metals.
Made up of three compartments, the electrochemical cell allows seawater to flow into its central chamber, where positively charged lithium ions pass through the LLTO membrane to a side compartment containing a buffer solution and copper cathode that is coated with platinum and ruthenium. Negative ions exit this feed chamber through a standard membrane. They pass into the third compartment containing a chloride solution and an anode made from platinum and ruthenium.
Using 3.25 volts, the cell generates hydrogen gas at the cathode and chlorine gas at the anode. This transports the lithium through the LLTO membrane, where it then accumulates in the side chamber. Now enriched with lithium, the water goes through four more processing cycles until it reaches a concentration of 9-thousand ppm. By adjusting the pH of the solution, this method produces lithium phosphate with only traces from other metal ions, making it pure enough to meet requirements for manufacturers of lithium-ion batteries. Researchers estimate only $5 of electricity could extract 2.2 pounds (1 kg) of lithium from seawater. Additionally, this method would also gather usable amounts of chlorine and hydrogen, which would further offset these costs. The wastewater could be desalinated further and used as freshwater.
How is Lithium Processed?
With the growing need for lithium in the electric vehicle industry and other industries requiring lithium-ion batteries, the need for lithium processing equipment has never been greater. Prater Industries has developed machinery and systems for processing not only lithium but other minerals vital to the economy of the future. Its durable and adaptable mineral processing equipment works for handling both bulk solid material and powdered minerals. We have decades of experience with custom-designing mineral systems and equipment for numerous applications, and our company’s customized solutions are used by leaders in both the chemical and mineral industries.
Prater’s solutions for powder and bulk solid chemical and mineral processing include:
- Classification and separation
- Design and integration of systems
- Feeding and metering
- Particle size reduction
- Toll processing
Our equipment for processing chemicals and minerals spans industries and can be custom-designed to suit a manufacturer’s specific needs.
The equipment Prater provides includes:
- Air classifiers
- Air classifying mills
- Cake breakers
- Centrifugal sifters
- Molinos finos
- Lump breakers and lump crushers
- Rotary airlocks, rotary valves, and rotary feeders
- Rotary sifters and rotary sieves