Recycling Lithium-Ion Batteries Explained: The 2 Methods

Recycling electronics is a delicate process in terms of the actual procedure and how difficult it can be for the average consumer to find a facility to dispose of the items properly. The lithium-ion batteries that power many of today's electronic devices just complicate the matter, as their energy density and flammable insides make them volatile enough that federal regulations govern how they can be transported. When it comes to recycling the elements of the batteries, scientists have arrived at two different techniques: Pyrometallurgy and hydrometallurgy, which must be performed to extract everything even if the batteries have already gone through a mechanical recycling process.

As the name suggests, pyrometallurgy uses heat to extract materials from a battery, generally using an electric arc or a shaft furnace. One benefit is that it can recycle batteries of various chemistries, like nickel-cadmium or nickel-metal hydride, not just lithium-ion. It's not perfect, though. "[T]he process has high-capital requirements and is also energy intensive while requiring off-gas cleaning," IDTechEx technology analyst Conrad Nichols told Assembly Magazine. "Pyrometallurgy produces a mixed metal alloy, as well as a slag stream, containing lithium, manganese, and aluminum. Therefore, this would still require further hydrometallurgical processing if all valuable metals were to be re-obtained at battery grade."

Hydrometallurgical recycling, meanwhile, uses water-based solvents to recycle "black mass" — the industry term for ground-up batteries — or to refine the metals extracted from batteries using pyrometallurgy. "The key benefits of hydrometallurgical recycling are that more of the valuable metals can be recovered, and it is less energy intensive than pyrometallurgical recycling,"  IDTechEx's Nichols continued. "The costs of reagents and high volumes of water consumption also pose some downsides. However, some recyclers [claim] that they are able to cycle water multiple times through the recycling process to maximize its efficiency."

Nichols added that while most of the hydrometallurgical recycling facilities are located in the Asia-Pacific region, some Western facilities understand how both recycling methods benefit the other and are adding hydrometallurgical capacity to their existing pyrometallurgical facilities. Hopefully, we'll see a future where additional energy doesn't have to be expended to ship battery materials halfway around the world to allow them to be fully recycled.