Li-ion batteries are widely used in various markets, such as in consumer electronics, electric vehicles (EVs) and stationary energy storage. However, as demand for Li-ion batteries continues to increase, the need to manage their sustainability through their entire lifecycle, including at end-of-life (EOL), is also becoming increasingly important. At end-of-life, Li-ion batteries can be recycled to re-obtain the contained valuable metals, such as nickel, cobalt, and lithium. Depending on the recycling technique employed, products from these processes may need further refining or processing to enable their re-introduction into new battery manufacturing. In their latest report, “Li-ion Battery Recycling Market 2023-2043“, IDTechEx discuss and analyze three key recycling technologies being employed by players commercially, including mechanical, hydrometallurgical and pyrometallurgical recycling.
Mechanical Recycling
Mechanical processing is the simplest technique, which is employed by many players globally, and is typically the initial step in Li-ion battery recycling. This often starts with a disassembly step, which is performed manually due to differences in EV battery pack design and requires a skilled workforce to achieve this. Typical steps thereafter include shredding, grinding, and crushing. This breaks down the high-value materials, separates them from foils and casing, and is performed in an inert atmosphere. Often, sieving is used to separate larger fragments of current collectors, casings, and separators from electrode materials, which are constructed of very fine powders. This results in the production of black mass, which requires further refining via hydrometallurgical or pyrometallurgical processing to produce battery-grade metal salts. The majority of players in Europe and North America currently only have mechanical recycling capabilities. Therefore, most of these recyclers do not currently have the capabilities to produce battery-grade materials that are ready to be introduced into new battery manufacturing. This black mass is typically transported to recyclers in the Asia-Pacific region that have these capabilities.
Pyrometallurgical Recycling
Pyrometallurgy refers to the use of heat to extract battery materials, typically performed at high throughput in an electric arc or shaft furnace. Advantages to the process include little pre-treatment requirements, and that it is battery chemistry agnostic, and so can receive various metal-containing waste streams as feedstock, such as NiMH, Ni-Cd and Li-ion batteries. However, the process has high-capital requirements and is also energy intensive while requiring off-gas cleaning. 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
Hydrometallurgical techniques can be used to recycle black mass directly or refine alloys produced from pyrometallurgy to form battery-grade metal salts. These salts can be re-introduced into new cathode precursor manufacturing and are, therefore, of higher value than black mass produced from mechanical recycling. In hydrometallurgical recycling, leaching, solvent extraction, or precipitation steps can be employed to selectively extract metals such as nickel and cobalt from black mass produced by mechanical recycling in the form of battery-grade salts. 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. However, the costs of reagents and high volumes of water consumption pose some downsides. Though, through interviews with IDTechEx, some recyclers have commented that they are able to cycle water multiple times through the recycling process to maximize its efficiency.
Currently, the majority of hydrometallurgical recycling capacity resides in the Asia-Pacific region, including key players such as SungEel HiTech, Exigo Recycling and ACE Green Recycling. However, players in Europe and the US recognize the benefits of hydrometallurgical processing and are in the process of expanding their hydrometallurgical capacities. Fortum recently commenced commercial operations of its hydrometallurgical plant in Harjavalta, Finland. This marks the first commercial-scale facility in Europe for hydrometallurgical recycling. In the US, Li-Cycle are planning to establish their own commercial-scale hydrometallurgical plant too.
Other Techniques
While these are generally the three most developed processes used by Li-ion battery recycling players, other routes are being explored. Namely direct recycling is a technique that involves mechanical pre-processing and component separation steps, followed by reactivating the battery material to recover the capacity lost during cycling, but without breaking down the crystal structure of the cathode material. However, this is a pre-commercialized technology being investigated by research bodies on a more lab-scale basis.
