From scooters to motorcycles, sportscars, school buses, trucks, trains, and even planes, it seems we are entering the era of electrified mobility. This has been due in large part to the rapidly falling costs and improving performance of lithium-ion batteries. Better batteries are enabling an increasingly wide array of electric personal, light, and heavy-duty vehicle technologies. The growth in deployments of lithium batteries will inevitably create a large flow of retired or used batteries. By 2030, analysts predict that retirements could exceed half a million vehicles annually or over 2 million metric tonnes of batteries per year.
Electric vehicles (EVs) are still a small part of the vehicle market and the few retired EV batteries coming out of vehicles are being tested in a range of pilot-scale applications or simply stored while technology or infrastructure for recycling improves. While the majority of consumer electronic wastes have historically been destined for the landfill, lithium batteries contain valuable metals and other materials that can be recovered, processed, and reused to make more batteries.
There are many promising strategies for recycling lithium-ion batteries (LIB) , but there are also technical, economic, logistic, and regulatory barriers to resolve. As the Hitz Climate Fellow for the Union of Concerned Scientists, I’ll be taking a look at some of the challenges and opportunities for battery reuse and recycling over the next year. This is a quick overview of the current state of battery recycling which highlights opportunities to close the loop on battery materials and create a sustainable value chain for lithium batteries.
The end of life?
When an electric vehicle comes off the road, either from accident or age, battery systems will need to be processed. After primary use in a vehicle, potential end of life pathways for used electric vehicle batteries include reuse, or repurposing (“second life”), materials recovery (recycling), and disposal. Regardless of whether batteries are reused, they will eventually need to be recycled or disposed. Understanding the opportunities and barriers to recycling is critical to reduce environmental impacts from improper disposal, and to account for benefits from recovered materials and avoided mining of virgin resources.
A handful of large-scale facilities recycle lithium batteries today using pyrometallurgical, or smelting, processes. These plants use high temperatures (~1500oC) to burn off impurities and recover cobalt, nickel, and copper. Lithium and aluminum are generally lost in this processes, bound in waste referred to as slag. Some lithium can be recovered from slag using secondary processes. Today’s smelting facilities are expensive and energy intensive, in part due to the need to treat toxic fluorine emissions, and have relatively low rates of material recovery.
According to the US Advanced Battery Consortium standards, an EV battery reaches the end of its usable life when its current cell capacity is less than 80% of the rated capacity. But there are still a lot of unknowns as to when EV batteries will be retired. For example, the average vehicle is on the road in the United States for more than 12 years; modern EVs with large lithium-ion battery packs have been on the market for less than 8 years, with over 50% of sales occurring in the last two years.
A second-life for batteries
A second-life application for used batteries is an appealing opportunity for battery and vehicle manufacturers to make EVs more affordable and potentially generate more profit. Reuse also extends the lifetime of batteries, and potentially displaces some new batteries from stationary applications, all of which reduces the overall impacts of battery production.
In some cases, batteries could be refurbished for use directly in another vehicle, potentially extending the useful life of many vehicle systems. So when a battery pack dies prematurely, functioning modules and cells can often be recombined to create refurbished battery packs for other vehicles.
300 kWh Second-life EV battery storage project at University of California Davis
Given the large size and high performance of modern vehicle batteries, retired batteries could still offer significant capacity after being retired from use in a vehicle. As batteries are charged and discharged, their performance degrades. Degradation results in is less stored energy being accessible for powering the vehicle; in other words, the vehicle won’t drive as far on a single charge. But in less demanding applications, EV batteries might get a second-life. While the high-power demands of a vehicle render stored energy inaccessible, batteries might be able to serve an additional 6 to 10 years in a lower-power, stationary application storing energy from solar panels to be used in off-grid or peak demand-shaving applications.
One key barrier for reuse has been the continually improving economics and performance of new batteries. The price of new batteries fell over an order of magnitude while performance has improved, effectively pricing out used batteries from some applications. The integrated construction and design of current battery packs and proprietary management software also limit component replacement and increase the costs of testing and repurposing.
Closing the loop
Regardless of whether batteries are reused, recycling and material recovery will eventually be required. Recovering the materials in LIBs decreases the need for new raw materials, lowers the battery’s life-cycle impact and improves energy security by reducing imports. The majority of recycling research and interest focuses on the battery cathode, which contains the highest value constituent minerals.
There are three general stages to battery recycling. The first stage is pretreatment, which primarily consists of mechanical shredding and sorting out plastic fluff and non-ferrous materials. Secondary treatment can follow, which involves separating the cathode from the aluminum collector foil with a chemical solvent. The final step is dissolving the cathode materials through either leaching chemicals (referred to as hydrometallurgy) or heat and electrolytic reactions (referred to as pyrometallurgy).
Automation could play an important role in making pretreatment more efficient and economical by enabling rapid disassembly of the battery into constituent components. Separation of battery components can yield recovered materials with higher purity and value. Researchers in the United Kingdom are developing robotic procedures for sorting, disassembling, and recovering valuable materials from Li-ion batteries which could eliminate human workers’ risk of electrical and chemical injury.
Pyrometallurgical processes for recovering cathode materials generally have larger negative environmental and climate impacts than some hydrometallurgical processes. This is in part due to the energy requirements and need to remove toxic pollutants from exhaust gases. After recovery through pyro (heat) or hydro (chemical) metallurgical processes, minerals often need to be re-refined before being resynthesized into a cathode compound and used to make battery electrodes.
In direct recycling, the cathode compound is kept intact and refunctionalized, yielding a cathode material with similar if not identical properties to the original compound. One of the highest value components of the battery is the synthesized cathode compound; direct recycling seeks to separate the compound intact, and recombine it with additional lithium (relithiation). Direct recycling offers the opportunity to avoid energy intensive refining and resynthesis of the cathode compound, further reducing the environmental impacts of battery production.
Recovery of critical minerals
A lithium battery is primarily composed of a short-list of important minerals which could be recovered and used to make new batteries, thereby lowering manufacturing costs. The cost of minerals in the battery represent nearly half the cost of today’s lithium batteries. The costs of the three most expensive ingredients in the battery cathode (i.e. cobalt, nickel, and lithium) have been highly volatile, fluctuating by as much as 300% in a single year, despite a >90% reduction in the overall price of EV batteries in the last ten years. Recycling and recovery of the valuable materials also reduces the potential quantity of material going to landfill from material scrap.
The recipe of transition metals in the battery cathode influence characteristics such as the energy density, power density, cycle life, safety and cost of batteries. The choice of cathode compound also influences the economics of recycling, as the value of the recovered materials may not be sufficient to cover the costs of expensive recycling processes. Cobalt is the most valuable component of the cathode alloy; reducing the cobalt content, as is the trend in battery technology, reduces the cost of production, but also reduces the incentive for recycling.
Recycling could decrease reliance on new mining, slow depletion of virgin materials, and reduce impacts on vulnerable populations along the value chain for batteries. For example, more than 60% of the world’s cobalt supply comes from Democratic Republic of Congo and is tied to armed conflict, illegal mining, human rights abuses, and harmful environmental practices. Recycling batteries and reformulating cathodes with a reduced concentration of cobalt could help lower dependence on foreign sources and raise the security of the supply chain.
Materials recovered from recycled batteries could be an important and environmentally preferable source of material supply for future batteries. Research has shown that optimal cathode recycling has the potential to be profitable, given a sufficient ratio of material content to material value. Perhaps more importantly, recycling could provide cost competitive and potentially environmentally preferable alternatives to production of cathode compounds from virgin materials.
Policy for sustainable batteries
There are clear reasons to pursue policies to promote safe and equitable disposal practices. The impacts of global flows of consumer electronics wastes offer one cautionary tale. Collection, logistics, data sharing, standardization, and investment in infrastructure are all likely to be barriers for creating a sustainable and circular system of battery production and recycling
Closing the loop on battery materials by recycling EV batteries is a critical step towards building better batteries. California is currently working to develop policies to ensure that 100% of electric vehicle batteries sold in the state are recycled or reused at their end of life. Policy mechanisms like standards for labelling and data interface, extended producer responsibility, responsible sourcing, and deposit or core charge could help to alleviate some of the key barriers listed above.
Development of a domestic supply chain for electric vehicle batteries, including secondary production of battery materials, could have important economic, environmental, and social impacts. Demand for battery manufacturing is growing rapidly, and recycling is likely to play a key role in the nearly trillion dollar market for lithium batteries and battery materials. Policy is going to play a key role in ensuring environmental sustainability and equity guide and inform the citing, design, and development of manufacturing and recycling facilities.
Uncertainty on the fate of used electric vehicle batteries is often cited as a challenge to future vehicle electrification efforts, but some concerns are not always supported by the facts. Batteries can be recycled economically with technologies available today. Future systems could further reduce pollution, climate emissions, and finite resource depletion associated with the battery life cycle.
In this fellowship, I am investigating the opportunities and challenges for recycling and reuse of electric vehicle batteries. I am hoping to better understand and quantify the impacts of battery deployments and retirements on demand for critical minerals, the potential for second-life storage, and the infrastructure required to recycle batteries. As part of the fellowship, I will also be posting a series of blogs on batteries which digs deeper into many of these issues. Stay tuned.