The use of a novel sub-class of per- and polyfluoroalkyl substances (PFAS) in lithium-ion batteries is polluting air and water, according to a new peer-reviewed study published in Nature Communications. Testing by the research team further found that these PFAS, called bis-perfluoroalkyl sulfonimides (bis-FASIs), demonstrate environmental persistence and ecotoxicity comparable to older notorious compounds like PFOA.
Lithium-ion batteries are a key part of our growing clean energy infrastructure, with uses in electric cars and electronics (e.g., cell phones, medical devices, smart watches, laptops). Demand is anticipated to grow exponentially over the next decade. Because only approximately 5 percent of lithium-ion batteries are recycled, studies project disposal of up to 8 million tons of lithium-ion battery waste by 2040. This study is the first cradle-to-grave evaluation of the environmental impacts of bis-FASI use in lithium-ion batteries.
“Our results reveal a dilemma associated with manufacturing, disposal, and recycling of clean energy infrastructure,” said author Jennifer Guelfo, an associate professor of environmental engineering at Texas Tech University. “Slashing CO2 emissions with innovations like electric cars is critical, but it shouldn’t come with the side effect of increasing PFAS pollution. We need to facilitate technologies, manufacturing controls, and recycling solutions that can fight the climate crisis without releasing highly recalcitrant pollutants.”
The researchers sampled air, water, snow, soil, and sediment near manufacturing plants in Minnesota, Kentucky, Belgium, and France. The bis-FASI concentrations in these samples were commonly at parts per billion levels. Data also suggested that air emissions of bis-FASIs may facilitate long-range transport, meaning that areas far from manufacturing sites may be affected as well. Analysis of several municipal landfill leachates in the Southeastern US revealed bis-FASI concentrations approaching 1 ppb, indicating that these compounds can also enter the environment through disposal of products including lithium-ion batteries.
Toxicity testing demonstrated that concentrations of bis-FASIs similar to those found at the sampling sites can change behavior and fundamental energy metabolic processes of aquatic organisms. Bis-FASI toxicity has not yet been studied in humans, though other, more well-studied PFAS are linked to cancer, infertility, and other serious health harms.
Treatability testing showed that bis-FASIs did not break down during oxidation, which has also been observed for other PFAS such as PFOS and highlights the persistence of this lesser-studied group of PFAS. However, data showed that concentrations of bis-FASIs in water could be reduced using granular activated carbon and ion exchange, methods that are already used to remove PFAS from drinking water.
“These results illustrate that treatment approaches designed for PFOA and PFOS can also remove bis-FASIs. Use of these approaches is likely to increase as treatment facilities are upgraded to comply with newly enacted EPA Maximum Contaminant Levels for PFAS,” said study author Lee Ferguson, associate professor of environmental engineering at Duke University.
The study showed that bis-FASIs are used in lithium-ion battery electrolytes and binders. Other fluorinated electrolytes are also used in lithium-ion batteries that do not meet the definition of PFAS. Additionally, other PFAS such as polyvinylidene fluoride (PVDF) have multiple uses in batteries. There is evidence in the scientific literature and online that researchers are starting to consider and even use fluorine-free alternatives for these battery components. However, “Fluorine-free does not guarantee safer,” the study authors caution. “All alternative materials developed for use in clean energy infrastructure merit evaluation of potential risks to human health and the environment to avoid regrettable substitution,” they add.
The study authors emphasize that this is a pivotal time for adoption of clean energy technologies that can reduce CO2 emissions. “We should harness the expertise of multi-disciplinary teams of scientists, engineers, sociologists, and policy makers to develop and promote use of clean energy infrastructure while minimizing the environmental footprint. We should use the momentum behind current energy initiatives to ensure that new energy technologies are truly clean.”