Harper, G., Sommerville, R., Kendrick, E. et al. Recycling lithium-ion batteries from electric vehicles. Nature 575, 75–86 (2019). https://doi.org/10.1038/s41586-019-1682-5
The mass adoption of electric vehicles is seen as an imperative step to help meet global targets for reducing greenhouse gas emissions and to improve air quality in urban centres. However, growing numbers of electric vehicles present a serious waste-management challenge for recyclers at end-of-life. The authors of this study put the potential scale of waste into perspective, highlighting that the electrification of only 2% of the current global car fleet would represent a line of cars—and in due course, of end-of-life waste—that could stretch around the Earth.
Nevertheless, spent batteries may also present an opportunity as manufacturers require access to strategic elements and critical materials for key components in electric-vehicle manufacture: recycled lithium-ion batteries from electric vehicles could provide a valuable secondary source of materials. In this paper, Harper et al outline and evaluate the current range of approaches to electric-vehicle lithium-ion battery recycling and re-use and highlight areas for future progress.
SOCIAL AND ENVIRONMENTAL IMPACTS
At the start of a lithium-ion battery’s (LIB) life – when considering the two main modes of primary production – it takes 250 tons of the mineral ore spodumene when mined, or 750 tons of mineral-rich brine, to produce one ton of lithium. The processing of large amounts of raw materials can result in considerable environmental impacts. For example, production from brine entails drilling a hole in the salt flat and pumping of the mineral-rich solution to the surface. However, this mining activity depletes water tables.
The authors highlight Chile’s Salar de Atacama as stark example. As a major centre of lithium production, 65% of the region’s water is consumed by mining activities which means local farmers must then import water from other regions. The demands on water from the processing of lithium produced in this way are substantial, with a ton of lithium requiring 1,900 tons of water to extract.
Of even greater immediate concern are cobalt reserves, which are geographically concentrated (mainly in the politically unstable Democratic Republic of the Congo). These have experienced wild short-term price fluctuations and raise multifarious social, ethical, and environmental concerns around their extraction, including artisanal mines employing child labour.
In addition to the environmental imperative for recycling batteries, there are clearly serious ethical concerns with the materials supply chain, and these social burdens are borne by some of the world’s most vulnerable people.
LIFE AFTER DEATH
There is wide acceptance that, for environmental and safety reasons, stockpiling (or worse, landfill) and wholesale transport of end-of-life electric-vehicle batteries are not attractive options, and that the management of end of-life electric-vehicle waste will require regional solutions.
In the waste management hierarchy, re-use is considered preferable to recycling to extract maximum economic value and minimize environmental impacts. Many companies in various parts of the world are already piloting the second use of electric-vehicle LIBs for a range of energy storage applications. Advanced sensors and improved methods of monitoring batteries in the field and end-of-life testing would enable the characteristics of individual end-of-life batteries to be better matched to proposed second-use applications. Even if all the benefits of second use are realized, however, it must be remembered that recycling (if not landfill) is the inevitable fate of all batteries. This paper highlights that some recent life-cycle analyses has indicated that the application of current recycling processes to the present generation of electric-vehicle LIBs may not in all cases result in reductions in greenhouse gas emissions compared to primary production. More efficient processes are urgently needed to improve both the environmental and economic viability of recycling, which at present is heavily dependent on cobalt content.
POWERING A NEW INDUSTRY?
The authors note that in many nations, the elements and materials contained in batteries are not available, and access to resources is crucial in ensuring a stable supply chain. Electric vehicles may prove to be a valuable secondary resource for critical materials. Careful husbandry of the resources consumed by electric-vehicle battery manufacturing—and recycling—surely hold the key to the sustainability of the future automotive industry.
There are a number of lessons that the future LIB recycling industry could learn from the highly successful lead–acid battery recycling industry. As a technology, lead–acid batteries are relatively standardized and simple to disassemble and recycle, which minimizes costs, allowing the value of lead to drive recycling. Unfortunately, for a rapidly developing technology such as electric-vehicle LIBs, such advantages are not likely to apply any time soon.
There is a clear opportunity for a more sophisticated approach to battery recovery through automated disassembly, smart segregation of different batteries and the intelligent characterization, evaluation and ‘triage’ of used batteries into streams for remanufacture, re-use and recycling. Yet, the design of current battery packs is not optimized for easy disassembly. Many of the challenges this presents to remanufacture, re-use and recycling could be addressed if considered early in the design process.
The move to greater automation and robotic disassembly promises to overcome some of these hurdles. A cell design for reclamation of materials is extremely appealing, with low-cost water-soluble binders. Beyond the scientific challenges of recycling LIBs, the ‘system performance’ of the LIB recycling industry will be strongly affected by a range of non-technical factors, such as the nature of the collection, transportation, storage and logistics of LIBs at the end-of-life. As these vary from country to country and region to region, it follows that different jurisdictions may arrive at different answers to the problems posed.