Environmental impacts of lithium-ion batteries
are batteries that use lithium as an anode. This type of battery is also referred to as a lithium-ion battery and is most commonly used for electric vehicles and electronics.
While they are a means of moving the world towards sustainable energy usage, there are associated environmental impacts of traditional lithium extraction techniques.
While lithium-ion batteries can be used as a part of a sustainable solution, shifting all fossil fuel-powered devices to lithium-based batteries might not be the Earth's best option. There is no scarcity yet, but it is a natural resource that can be depleted. According to researchers at Volkswagen, there are about 14 million tons of lithium left, which corresponds to 165 times the production volume in 2018.
Traditional extraction methods include lithium mining from salt brines, lithium-rich clay, and ores. With these techniques, environmental impacts such as loss of freshwater through evaporation, release of harmful gases, chemical leakage, and many other adverse consequences.
In an attempt to minimize the harmful environmental impact of traditional methods, electrochemical extraction techniques have been developed. These methods both improve efficiency and have less secondary environmental impacts. Electrochemical extraction methods facilitates the dissolution of metal ions by utilizing the electric field. As such, it does not require the same level of heat and concentration of chemicals used in the traditional acid leaching. Electrochemical methods from brine lakes significantly reduces the time taken to obtain lithium, thus reducing the possibility of heavy metal leaching and depletion of fresh water sources.
History
The first type of lithium battery was created by the British chemist M. Stanley Whittingham in the early 1970s and used titanium and lithium as the electrodes. Applications for this battery were limited by the high prices of titanium and the unpleasant scent that the reaction produced. Today's lithium-ion battery, modeled after the Whittingham attempt by Akira Yoshino, was first developed in 1985.Extraction
Lithium is extracted on a commercial scale from three principal sources: salt brines, lithium-rich clay, and hard-rock deposits. Each method incurs certain unavoidable environmental disruptions. Salt brine extraction sites are by far the most popular operations for extracting lithium, they are responsible for around 66% of the world's lithium production. The major environmental benefit of brine extraction compared to other extraction methods is that there is very little machinery needed to be used throughout the operation. Whereas hard-rock deposits and lithium-rich clays both require relatively typical mining methods, involving heavy machinery. Despite this benefit, all methods are continually used as they all achieve relatively similar recovery percentages. Brine extraction achieves a 97% recovery percentage whereas hard-rock deposits achieve a 94% recovery percentage.Traditional extraction methods
Continental brine extraction
uses open-air evaporation to concentrate the brine over time. This results in large quantities of water being lost due to evaporation. It is worth noting that in general, this brine being evaporated has a very high salinity, making the water unusable for any agricultural or human consumption. Afterwards, the concentrated brine is moved to a nearby production facility to produce Li2CO3 and LiOH•H2O. These production facilities are responsible for the bulk of the atmospheric pollution caused by brine extraction sites, releasing harmful gasses such as sulphur dioxide into the air.The majority of brine extraction sites are situated in South America, more specifically, in Chile and Argentina, where around half of the world's lithium reserves exist in a place referred to as the "lithium triangle". In Chile, the world's second-largest lithium producer, the nation's two active mines, run by Sociedad Química y Minera and Albemarle, are both located on the Salar de Atacama salt flat in the Atacama Desert. Tests performed on the brines of these mines showed that the brine has ~350 g/L of total dissolved solids. Studies on this mine and the area's water tables have shown that the total water storage of Salar de Atacama decreased by -1.16 mm per year from 2010-2017. There is a complex divide among and within local communities, with some accepting payouts from the mining corporations and taking part in their community development initiatives, whilst others are either neglected by such programs or refuse the corporations' offers due to their aforementioned environmental concerns. In Tagong, a small town in Garzê Tibetan Autonomous Prefecture China, there are records of dangerous chemicals such as hydrochloric acid leaking into the Liqi River from the nearby lithium mining facilities. As a result, dead fish and large animals were seen floating down the Liqi River and other nearby rivers near the Tibetan mines. After further investigation, researchers found that this may have been caused by leakage of evaporation pools that sit for months and sometimes even years.
Hard-rock deposits
Lithium can also be extracted from hard-rock deposits. These deposits are most commonly found in Australia, the world's largest producer of lithium, through spodumene ores. Spodumene ores and other lithium-bearing hard-rock deposits are far less abundant throughout the world than continental brines. Although the deposits are far less commonly found and available for mining, the operating costs are very similar to the costs of operating a brine extraction operation. As a result, hard-rock deposit extraction sites are continuing to be created and used even though salt brines are much more common to find and typically bear a smaller environmental impact.Lithium-rich clays
Extracting lithium from lithium-rich clays first involves mining the clays themselves which results in lots of atmospheric pollution. There are several minerals within clay that contain lithium such as, lepidolite, hectorite, masutomilite, zinnwaldite, swinefordite, cookeite, and jadarite. After extracting these minerals from the ground, the clays are processed to extract the lithium, this is typically done through chemical reactions like acidification. This chemical process can result in harmful gasses and chemicals being produced as byproducts which can easily result in pollution if not handled properly. Lithium-rich clays are the third major source of lithium, although they are far less abundant than salt brines and hard-rock ores containing lithium. To be exact, lithium-rich clays make up less than 2% of the world's lithium products. For comparison, brine extraction represents 39% and hard-rock ores represent 59% of the lithium production.Electrochemical Methods
Electrochemical Leaching from Ores
With the rapid demand increase for lithium, it is critical to develop alternative methods of lithium extraction than conventional brine to form a reliable supply-chain. Hence, there has been development of a new extraction method called electrochemical leaching to minimize environmental footprint and energy consumption.The main drawback of acid leaching is the high level of energy consumption used to reach the high temperatures required for calcination. Basic leaching methods, although requiring lower temperatures, need to separate impurities in an additional round of treatment. These limitations of chemical leaching methods call for new leaching techniques to reduce environmental impact.
Electrochemical leaching facilitates metal ion dissolution by using the electric field. It does not require the same high temperatures and high concentrations of leaching agents for reaction activation as acid leaching methods and thus has a lesser harmful environmental impact. It can also utilize wind/solar energy for electricity generation. A study conducted by researchers to test the efficacy of the new method found an efficiency of 92.2% was achieved.
Electrochemical Methods from Brines
Lithium extraction from ores uses a high level of energy and technical complexities, as such most of the world's lithium supply is extracted from brine lakes. Traditional mining methods have severe environmental consequences. The traditional extraction method of solar evaporation from salt brines is an extremely time consuming process, taking anywhere from 1-2 years. Meanwhile, this includes the evaporation and hence loss of freshwater, which can cause heavy metal leaching and local agricultural water deficiency.Original methods of extraction from brine lakes are only feasible for low magnesium to lithium ratios. Electrochemical methods have been developed and employed for these brine lakes with higher Mg/Li ratios. CDI is an emerging technology which uses charged electrodes to absorb and remove ions from saline solutions. This method has low energy consumption, low cost, and no secondary chemical pollution. It removes ions from saline solutions by applying an electric field across two carbon electrodes, which attract cations and anions to their respective cathodes, thus successfully removing ions from the solution.