Recycling Lead-Acid Batteries Is Easy. Why Is Recycling Lithium-ion Batteries Hard?

The lithium-ion batteries in today’s electric vehicles outperform older lead-acid batteries by almost every measure, except one. Lead-acid batteries are still the single-most recycled product in the world.

Although lithium-ion batteries are set to power a clean-energy transition, more than 100 million lead-acid batteries are still sold each year in the United States, mostly as starter batteries for cars, trucks, and boats.

When those lead-acid batteries die, nearly all of them get recycled. In fact, the lead-acid battery industry claims a domestic recycling rate of 99 percent. In 2021, the US produced nearly one million metric tons of recycled lead. Almost all of that recycled lead was used to manufacture new batteries.

What is interesting is that none of this is actually new. Lead-acid batteries have been recycled since the 1920s. As early as 1930, the industry described lead for batteries as a “loan” rather than a form of “consumption.” Prior to the 1960s, hundreds of small-scale lead recycling operations operated in and around US cities, making this an early form of urban mining.

These urban lead recycling operations were also a significant source of pollution. One of the earliest epidemics of lead poisoning was tied to battery recycling operations in Baltimore, Maryland, in the 1930s. In some places, it is still possible to identify the sites of abandoned lead-acid battery recycling operations based on elevated levels of heavy metals in the soil.

In the 1980s, however, the industry went through a major restructuring. New environmental laws forced recyclers to upgrade pollution controls. In response, many small recyclers closed. Those that remained consolidated operations into integrated battery recycling operations with improved pollution controls. Today, a dozen highly regulated secondary lead smelters recycle the vast majority of the US’s spent lead-acid batteries.

With global production of lithium-ion batteries now overtaking lead-acid batteries, it is worth asking why lead-acid batteries have been recycled for so long and so efficiently, and what lessons that offers for closing the loop on the lithium-ion batteries. Consider these three points:

First, the chemistry and format of lead-acid batteries is highly standardized, which simplifies recycling. Unlike with lithium-ion batteries, which come in a range of chemistries and a variety of shapes (cylindrical, flat, pouch, etc.), the relative uniformity of spent lead-acid batteries reduces the need for sorting spent lead-acid batteries by chemistry, shape, or size. That facilitates bulk processing.

Second, the metals content of lead-acid batteries is almost entirely metallic lead and lead oxide paste — both of which are usually recovered through pyrometallurgical recycling processes at more than 2000 degrees Fahrenheit. After processing, the recovered lead is both the functional equivalent of and cost-competitive with lead sourced from primary ore.

In comparison, lithium-ion batteries are far more materially complex. That requires tailoring lithium-ion recycling processes to recover a range of cathode materials (lithium, cobalt, nickel, manganese, iron, etc.), anode materials (graphite), and conductors (aluminum and copper). These complexities pose significant challenges for efficacy of recovering materials and processing them for re-use cost-effectively.

Third, starting in the 1980s, the federal government and states prohibited the disposal of lead-acid batteries, due to lead’s high toxicity. Although some spent lead-acid batteries got shipped abroad for recycling, most are recycled domestically. (Concerns have been raised about spent battery shipments to less well-regulated facilities in Mexico.) That has meant recycling has played an important role in ensuring the United States has had an abundant and reliable source of domestic lead.

Looking ahead, the scale of recycling of lithium-ion batteries is set to expand rapidly. High volume of spent large-form electric car batteries promise to drive the harvest of scale needed to close the loop on lithium-ion batteries. Studies indicate that recycling has the potential to reduce the cumulative demand for lithium, cobalt, and nickel needed to electrify the transportation sector by up to 30 percent between 2020 and 2050.

Scaling up lithium-ion battery recycling will also create opportunities to improve the sustainability of recycling operations. Existing pyrometallurgical processes for lithium-ion batteries often recover only a fraction of the metals content of spent batteries (usually driven by the value of cobalt). Direct recycling strategies, such as those being researched at Argonne National Laboratory’s ReCell Centerhave the potential to substantially improve materials recovery and to reduce the energy inputs and potential pollutants from lithium-ion battery recycling.

Although there are growing private-sector and governmental initiatives to promote recycling in the United States, the flow of spent lithium-ion batteries, and the resources they contain, could easily be diverted overseas. In the long term, a robust US lithium-ion recycling industry can play an important role in securing domestic sources of advanced battery materials. Although its significance is little appreciated, that is just the role the lead recycling industry has played in supporting the domestic manufacture of lead-acid batteries since the mid-twentieth century.

This post is adapted from James Morton Turner’s forthcoming book, Charged: A History of Batteries and Lessons for a Clean Energy Future (August 2022). You can learn more about Charged at Turner tweets at @_jay_turner


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