Challenges to Making Lithium-ion Batteries and Electric Vehicles Environmentally Friendly
By Haochuan Zhang
Ever since their development in the late 1980s, lithium-ion batteries have become a ubiquitous technology that has truly revolutionized many aspects of our lives, including the transformation of portable electronics and electric vehicles. Despite their high energy density relative to other rechargeable battery systems, Li-ion battery waste is substantial, and their production, use, and recyclability call into question serious environmental and ethical concerns that must be addressed on a global scale.
Batteries store electric energy in the form of chemical bonds (see this quick animated guide on how batteries work). Since their invention by Alessandro Volta at the end of the 18th century, batteries have become an indispensable part of our daily life. The development of rechargeable lithium-ion batteries in the early 1990s is regarded as the most significant milestone in battery technologies and was even awarded the 2019 Nobel Prize in chemistry. The lithium-ion battery has played a crucial role in powering the modern world, but questions remain about its environmental impact. As the world scrambles to replace fossil fuels with clean energy, fancy “zero-emission” electric vehicles have catalyzed a huge surge of battery technology advancement and a tremendous commercial market. Nowadays, more and more people start to question whether the CO2 footprint from the manufacture of electric vehicles can offset the CO2 emissions that otherwise come from internal combustion engines.
Where does lithium come from?
Lithium metal doesn’t exist in nature because it’s highly reactive. Lithium metal will rapidly react with air or water to form less reactive salts (‘salt’ is a generic term for a variety of minerals, table salt or sodium chloride is just one of these). These lithium salts can be found in underground deposits of clay, mineral ore, and brine, as well as in geothermal water and seawater. The briny lakes with the highest lithium concentrations (also known as ‘salars’) are found under the deserts of Bolivia, Argentina, and Chile, in an area called the “lithium triangle” (Figure 1). This area encompasses one of the largest lithium-producing places in the world, and the lithium obtained from there is mostly recovered in the form of lithium carbonate; a more stable compound that can then be transformed into other chemicals for manufacturing companies.
Brine mining is a time-consuming process, usually taking anywhere between 8 months to 3 years. Miners start by drilling a hole in the salt flats and pumping salty, mineral-rich brine to the surface, then, they leave it to evaporate for months, first creating a mix of manganese, potassium, borax, and lithium salts, which are later filtered and placed into another evaporation pool. After approximately 12-18 months, the mixture is filtered enough so that lithium carbonate can be extracted. Although cheap and effective, the process requires a lot of water (an estimated 500,000 gallons per ton of lithium). This is problematic for local agricultural communities like Chile’s Salar de Atacama, where mining has consumed 65% of the region’s water. [1]
Furthermore, toxic chemicals can leak from the evaporation pools to the water supply. This may include hazards like hydrochloric acid used in lithium processing and other waste products filtered out of the brine at each stage. In Australia and North America, lithium is mined from rock (e.g. spodumene) by more traditional methods, however, still requiring the use of biohazardous chemicals in order to extract lithium in a useful form. For instance, researchers in Nevada have found impacts on fish as far as 150 miles downstream from a lithium processing plant. [2]
Recycling lithium-ion batteries
Global annual sales of electric vehicles exceeded one million units for the first time in 2017 (Figure 2). With the explosively growing market of electric vehicles, piles of lithium-ion batteries were packed onto cars. Unfortunately, less than 5% of lithium-ion batteries are recycled today. In other words, most of those spent batteries will be disposed of in landfills, which will create significant environmental and social impacts on our society. First, if we consider the production of lithium, it takes 250 tons of the mineral ore spodumene or 750 tons of mineral-rich brine to produce 1 ton of processed lithium.[3] This production process can result in considerable environmental impacts as alluded to earlier. Second, 70% of the world’s cobalt, an essential element in lithium-ion batteries’ cathode, comes from the Congo, a country plagued by continuous political instability and violence.[4] Furthermore, miners in Congo work under hundreds of feet ground with few safety measures, exposing them to a high level of toxic metals and dangerous working conditions that frequently result in injury, or even death. To save valuable resources and mitigate the environmental and social impacts of lithium mining, it’s therefore necessary to spend proactive effort for the world to deal with the question of the widespread batteries looming on the horizon.
The reason why lithium-ion battery recycling is not well-established is mostly due to economic and technological factors. The retrieved raw material barely pays off labor cost, which includes the collection, transportation, sorting, shredding, separation of metallic and non-metallic materials, and neutralization, smelting, and purification of hazardous substances and recovered materials. Additionally, the complexity and low yield of recycling make it often cheaper to directly mine raw material rather than to recycle it.
Fortunately, positive changes are starting to take place. Driven by the foreseeable enormous quantity of aging batteries from electric vehicles, academia and industry are investing more effort in developing new battery recycling technologies. For instance, in 2019, the US Department of Energy (DOE) announced the creation of the ReCell Center; the Department’s first lithium-ion battery recycling research and development center. With a $15 million investment and headquartered at Argonne National Laboratory, the ReCell Center now supports more than 50 researchers from six national laboratories and universities. Furthermore, the DOE also launched the $ 5.5 million Battery Recycling Prize to encourage entrepreneurs to find innovative solutions for collecting and storing used lithium-ion batteries and transporting them to recycling centers. [5]
The carbon footprint of electric vehicles
Electric vehicles indeed have no tailpipe, hence, no CO2 is emitted into the atmosphere as with gasoline or diesel combustion in conventional cars. But when collectively considering the processes of lithium-ion battery production, car manufacturing, and battery-charging, electric vehicles still consume considerable amounts of fossil fuels and contribute to greenhouse gas emissions.
Similar issues can be pointed out in regards to the process of car manufacturing and battery charging. For instance, Mercedes-Benz’s electric-drive system integration department estimates that manufacturing an electric car may pump out, on average, more greenhouse gases than a conventional car.[7] On the other hand, an electric motor is powered by a large lithium-ion battery pack which must be plugged into a charging station or a wall outlet to charge. The required electric energy for charging is mostly produced by burning fossil fuels, already resulting in significant CO2 emissions. A recent study by the Union of Concerned Scientists investigated the magnitude of car charging-related emissions and found that the fuel-economy equivalent of battery-electric vehicles relative to electricity powered by natural gas is 58 milers per gallon (in terms of greenhouse-gas emissions); this the value could be much better if you switch to renewable energy sources, but only a small portion of the current worldwide electricity comes from renewable sources. [8]
In 2017, The IVL Swedish Environmental Research Institute reported that the production of lithium-ion batteries for light electric vehicles releases on average 150-200 kg of CO2 equivalents per kWh battery.[6] Their analysis found that it would take a Nissan Leaf 2.7 years and a Tesla Model S 8.2 years of driving to compensate for the emission associated with their battery pack production. It’s worth noting that the estimation was based on battery production in Sweden, where solar, wind, and hydropower account for half of the country’s electricity. Meanwhile, battery companies in the United States and China still rely heavily on non-renewable energy sources coming from coal, oil, and natural gas, making the CO2 emission mitigation efforts even more complicated. Yet another critical question to consider is whether electric cars or battery packs can live to survive such long periods of time.
Nevertheless, people are still accelerating the pace to embrace the era of electric vehicles. Large cities are now considering immediate how to improve the immediate air quality of their residents. Following this trend, every major carmaker has put forward plans for electric vehicles to replace gasoline cars. Many governments, like the EU and China, have already set up ambitious goals to promote the development of an electrified future.
Closing Thoughts: Lithium-ion batteries have dominated the handheld electronics market and as they are utilized in electric vehicles we need to be cognizant of the net change to overall CO2 emissions. Mining and refining lithium both produce significant amounts of carbon and battery recycling is currently in its infancy. Still there are many groups working to make battery recycling the norm rather than the exception. We have hope that battery design will advance far enough in the coming decades to make the electric car a central pillar of the fight against Climate Change.
Reference
[1] Katwala, Amit. The Spiralling Environmental Cost of Our Lithium Battery Addiction. WIRED UK, 3 Aug. 2018; www.wired.co.uk/article/lithium-batteries-environment-impact
[2] Koop, Fermin. What’s behind Lithium Mining? Here’s All You Need to Know. ZME Science, 9 Jan. 2020; www.zmescience.com/science/lithium-mining-098534
[3] Harper, G., Sommerville, R., Kendrick, E. et al. Recycling lithium-ion batteries from electric vehicles. Nature 575, 75–86 (2019); doi.org/10.1038/s41586-019-1682-5
[4] Murray, James. Is the Nobel Prize-winning lithium-ion battery really having a positive impact on the environment? NS Energy, 2019; www.nsenergybusiness.com/features/lithium-ion-battery-environmental-impact
[5] Jacoby, Mitch. It’s time to get serious about recycling lithium-ion batteries, Chemical & Engineering News, 2019, 97, 28; cen.acs.org/materials/energy-storage/time-serious-recycling-lithium/97/i28
[6] Romare, M., & Dahllöf, L. (2017). The life cycle energy consumption and greenhouse gas emissions from lithium-ion batteries. Stockholm. Zugriff am, 23, 2017; tffforum.de/uploads/default/original/3X/6/2/621315d4b3fd0cb17525756f42e3d2beedbf1758
[7] Behrmann, Elisabeth, et al. Electric Cars Are Clean, but Their Batteries Can Be Dirty. The Seattle Times , 30 Oct. 2018; www.seattletimes.com/business/electric-cars-are-clean-but-their-batteries-can-be-dirty
[8] Nealer, R., Reichmuth, D., and Anair, D. (2015). Cleaner cars from cradle to grave. Cambridge, MA: Union of Concerned Scientists. www.ucsusa.org/sites/default/files/attach/2015/11/Cleaner-Cars-fromCradle-to-Grave-full-report.pdf
—Haochuan Zhang is a graduate student researcher at Boston College.