Researchers have compared the environmental effects of recycling lithium-ion batteries with mining new materials. Their findings show that recycling is much more environmentally friendly, producing lower greenhouse gas emissions, using less water, and requiring less energy.
A recent lifecycle analysis from Stanford University, published in Nature Communications, highlights that recycling lithium-ion batteries to reclaim essential metals is significantly eco-friendlier than extracting fresh metals. This approach could also reduce the long-term uncertainty surrounding the supply of critical minerals used in batteries, both physically and geopolitically.
Lithium-ion battery recyclers obtain materials from two primary sources: defective scrap from battery producers and “dead” batteries collected mainly from workplaces. The recycling process recovers valuable metals like lithium, nickel, cobalt, copper, manganese, and aluminum from these materials.
The analysis assessed the recycling process’s environmental impact, demonstrating that it generates less than half the greenhouse gas emissions (GHGs) compared to traditional mining and refining of these metals. Additionally, recycling consumes about a quarter of the water and energy required for extracting new metals. Notably, the environmental benefits are greater for scrap materials, which made up around 90% of those analyzed, resulting in only 19% of the GHG emissions, 12% of the water usage, and 11% of the energy consumption compared to mining. While not specifically quantified, reduced energy consumption often leads to fewer pollutants, such as soot and sulfur.
“This study indicates we have the opportunity to design battery recycling to maximize its environmental benefits. We can shape the future,” noted William Tarpeh (BS ’12), an assistant professor at Stanford’s School of Engineering and senior author of the study.
Importance of Location
The environmental effects of battery recycling are profoundly influenced by the geographic location of the processing facility and its energy sources.
“If a battery recycling plant is in an area that uses a lot of coal-generated electricity, its climate benefits would be lessened,” explained Samantha Bunke, a PhD student at Stanford and one of the study’s lead investigators.
“Conversely, there are significant concerns about freshwater shortages in areas where cleaner electricity is used,” Bunke added.
The data for this study primarily came from Redwood Materials in Nevada, the largest lithium-ion battery recycling facility in North America, which benefits from the cleaner energy mix in the western U.S., including hydropower, geothermal energy, and solar power.
Transportation plays a critical role as well. For instance, cobalt is predominantly mined in the Democratic Republic of the Congo. After extraction, around 75% of this cobalt is transported via land and sea to China for refinement. Meanwhile, the majority of the world’s lithium is sourced from Australia and Chile, which also gets shipped to China for processing. In contrast, battery recycling involves gathering used batteries and scrap and then transporting them to recycling facilities.
“We found that the average transport distance for mining and refining the active metals in batteries is about 35,000 miles (57,000 kilometers)—equivalent to traveling around the world one and a half times,” said Michael Machala, PhD ’17, who is also a lead author of the study.
“In comparison, our estimate for the transportation of used batteries from a cell phone or electric vehicle to a hypothetical processing facility in California was only about 140 miles (225 kilometers),” Machala added. This estimate is based on the likely optimal placement of future refining facilities near abundant U.S. recyclable batteries.
Innovative Processes
The environmental results from Redwood do not necessarily reflect the overall performance of the nascent battery recycling industry for used batteries. Traditional pyrometallurgy, a common refining method, is highly energy-intensive and usually requires temperatures exceeding 2,550 degrees Fahrenheit (1,400 degrees Celsius).
However, Redwood has developed a patented process called “reductive calcination,” which operates at much lower temperatures, does not rely on fossil fuels, and produces more lithium than traditional methods.
“Similar emerging processes in research labs also utilize moderate temperatures without fossil fuels,” noted Xi Chen, the third lead author and a postdoctoral scholar at Stanford during the research and currently an assistant professor at City University of Hong Kong.
“Whenever we presented our research, industry representatives were eager to ask questions and apply our findings to enhance their practices,” Chen added. “This study can guide the scaling of battery recycling companies, emphasizing the need for strategically located facilities. Other states besides California harbor aging lithium-ion batteries from cell phones and EVs.”
Future Outlook
While industrial battery recycling is on the rise, senior author Tarpeh believes it is not progressing quickly enough.
“Forecasts suggest that we could deplete our new supplies of cobalt, nickel, and lithium within the next decade. Although we might resort to mining lower-grade ores for a period, 2050 and its associated targets are rapidly approaching,” he remarked.
The U.S. currently recycles approximately 50% of its available lithium-ion batteries while achieving a successful 99% recycling rate for lead acid batteries for many years. Given that used lithium-ion batteries comprise materials that can be up to ten times more economically valuable, there is substantial potential for improvement, according to Tarpeh.
“To prepare for a future with a significantly greater supply of used batteries, we must strategically develop a recycling framework from collection to processing, minimizing environmental damage,” he asserted. “It is also hoped that battery manufacturers will place a greater emphasis on recyclability in their future designs.”
