AMS Winter 2022-23
Sustainability – Batteries
Production today is geared towards premium vehicles. In modular assembly, we see an opportunity to be even more flexible…flexibility is even more important than maximun production units.
Gerd Walker, Board member for production, Audi
Manufacture, recycle, repeat – Developing sustainable battery materials
At present much of the automotive industry’s focus is on manufacturing enough electric vehicle batteries to meet the growing demand, but there is now an increasing amount of development being directed into creating a more sustainable supply of critical materials and managing end-of-life batteries. Report by Mike Farish
To be seen as genuinely more environmentally efficient alternatives to internal combustion engine vehicles, EVs must be so over their whole lifetime.
In practice that has to mean that there will also have be practicable processes to facilitate recycling and ideally re-use of the battery materials that form the most fundamental aspect of EV technology. Perhaps the foremost emerging force in the business of recycling and reusing the materials in spent EV batteries at least in the US is Redwood Materials based in Carson City, Northern Nevada. The company is in the most literal sense itself a result of the growth of the EV manufacturing industry since its CEO and founder is Jeffrey ‘JB’ Straubel, who for the 15 years previously was chief technical officer with arguably the best-known specialist EV manufacturer Tesla.
Over the last year the company has initiated a series of partnerships with major car makers to establish as far as possible ‘closed loop’ recycling operations in which material from spent batteries is reprocessed for fresh use in new ones. In September 2021, Redwood agreed a deal with Ford in the US in which the two committed themselves to cooperating in order “to integrate battery recycling into Ford’s domestic battery strategy.”
Redwood’s recycling technology is claimed to be able to recover in most cases more than 95% of materials such nickel, cobalt, lithium and copper in spent EV batteries. These can then be reused in new batteries with Redwood shaping up to produce anode copper foil and cathode active materials for future battery production. The seriousness with which Ford views the issue was underscored by the fact that the car maker agreed to invest $50m into Redwood to help the company’s expansion plans.
Comprehensive battery recycling programme for California
Subsequently in February 2022 Redwood initiated what it described as “the most comprehensive electric vehicle battery recycling” programme so far in the US. Beginning in California this initiative again involved Ford but also this time Volvo, with Redwood stating that it would “accept all lithium-ion and nickel metal hydride batteries in the state.”
A key factor about California, the company points out, is that as the US State that has probably led the way in the adoption of EVs it will also necessarily be at the forefront of the need for appropriate recycling services when those initial vehicles become redundant. At the time Redwood stated that it was accepting some 6GWh of lithium-ion batteries each year the equivalent of those used by 60,000 EVs, a figure which it even then described as “most of the recycled lithium-ion batteries in North America today”.
Today, the company notes, the two most critical and expensive components of lithium-ion batteries, the cathode and the anode, are produced almost entirely in Asia. As such the current US supply chain would require the relevant metals, irrespective of whether they were newly mined or recycled, to travel outside the United States because there is a gap in the US between critical mineral extraction and domestic battery cell manufacturing. In consequence the company describes itself as “working to close this gap by domestically producing large-scale sources of both anode and cathode materials produced from as many recycled batteries as available, augmented with sustainably mined materials.”
But the amount of battery materials the company is handling is already ramping up markedly. Redwood says it is now receiving 8-10 GWh of end-of-life batteries annually, the equivalent of about 100,000 electric vehicles, and plans to use recovered materials to manufacture 10 GWh of both anode and cathode materials by 2025, enough to produce more than one million electric vehicles a year. By 2030 it is targeting 500GWh, enough to supply over five million electric vehicles.
The company says it is implementing several recycling processes that it has developed for its own use in-house. It has done so in part because it handles more than just EV battery waste - “everything from large packs from EVs and energy storage systems to small consumer electronics like wireless headphones and toothbrushes”. It says it works with vehicle manufacturers such as Toyota, Ford and Volkswagen Audi as well as battery manufacturers like Panasonic, consumer device retailers like Amazon and electric utilities.
All the material is ultimately processed in a hydrometallurgy process though some batteries begin the recycling process either in mechanical separation or in a proprietary calcination process that makes use of residual energy in the end-of-life batteries to power the process without the use of any fossil fuels.
As things stand the company is already confident that the large majority of lithium-ion batteries recycled in North America come through its doors. It says its existing Battery Materials Campus about 45km from its headquarters and a projected East Coast site will both recycle, refine, and manufacture anode and cathode materials at scale in the US for the first time with an increasing amount of recycled content as a correspondingly increasing number of end-of-life batteries become available each year.
US government backed R&D into closed loop processes
But the US is also the scene for a comprehensive government-backed programme of research and development into the recyclability of lithium-ion batteries specifically aimed at enhanced ‘closed loop’ processes that minimise the need for fresh material input to the supply chain. The ReCell Centre which was launched in 2019 is not despite the name a single location but a dispersed collaborative effort involving three US National Laboratories plus three universities.
The Laboratories are the Argonne National Laboratory in Illinois, the Oak Ridge National Laboratory in Tennessee and the National Renewable Energy Laboratory (NREL) which has sites in Colorado and Alaska in addition to its Washington DC headquarters. The universities are Michigan Technical University, UC San Diego and Worcester Polytechnic Institute.
Each brings a distinct set of competences to the collective effort. In the case of the Laboratories, for instance, Argonne is described as ‘building a process development facility’, NREL as evaluating ‘second life’ issues and Oak Ridge as focussing on ‘the design of cells and electrodes to enhance recyclability’ and ‘anode graphite separation methods’.
As such there are several different strands of research underway at any one time. One of them that involves Dr Ilias Belharouak, head of the electrification section at Oak Ridge, is aiming for a quite fundamental change in the effectiveness of the recycling processes used for lithium-ion batteries.
Dr Belharouak says he has been involved in the development of lithium-ion technology for over 20 years. Indeed, he describes his commitment to the area as a personal “passion”. What he is focussed on now, he further explains, is the effort to develop what he terms “direct recycling” procedures in which as far as possible the active materials in the batteries are recovered in their original formulation so that they are very close to being ready for immediate re-use without any need for comprehensive remanufacture.
“Today we have two main recycling processes for lithium-ion batteries – pyrometallurgical and hydrometallurgical,” explains Dr Belharouak. Both involve the use of sulphuric acid to break down the spent battery materials, with the first of them, as the name indicates, preceded by an incineration stage. “So, we can get back to the elements but have to remanufacture anode and cathode materials,” he says. “But what we want is to be able to recover materials so that they can be put back to manufacture with perhaps just a little remediation.”
Most specifically, Dr Belharouak confirms, the primary aim is to obviate the use of both the thermal and acidic processes. The latter especially, he indicates, is both difficult and approximate in its effectiveness. “The separation chemistry to recover materials like nickel, cobalt and aluminium, for instance, is complex and no separation chemistry today can do it perfectly,” he states. “So, we want to avoid burning and acid.”
The alternative process that Dr Belharouak and his colleagues are seeking to develop instead involves a more benign set of procedures. “We want to recover active cobalt and lithium-based materials, so we impregnate with a green solvent to peel them off and then use mesh filtration to separate them,” he states.
Moreover, Dr Belharouak states that this recycling process is “now at an advanced R&D stage”. Between them, he indicates, the three Laboratories involved in the ReCell initiative do have prototype installations that prove out the viability of the overall process albeit so far with only small test quantities.
Dr Belharouak also confirms that even if the process reaches the stage of full industrial implementation that some remediation procedures are still likely to be necessary. “We would need to add some lithium to the cathode materials,” he says. “But the aim must be to get the materials back to the state in which they were originally manufactured. If the process is going to be commercially viable then the performance of recovered materials must be at least equal to that of their initial formulation.”
Improving the battery performance and lifecycle
Now, though, the main emphasis on ensuring the sustainability of EV batteries is right up front and is focussed on enhancing their efficiency in terms of storing electric charge so that in the most straightforward terms they provide the maximum range for the minimum weight and space. That is very much the message put forward by Karandeep Bhogal, senior automotive specialist with UK-based developer of advanced lithium-ion (Li-ion) battery materials Nexeon.
Bhogal says that Nexeon has already developed a process to produce anode materials utilising two main raw materials, respectively activated carbon and the silicon-hydrogen gas silane. The distinctive features of that process he further explains are a unique set of process parameters and fewer process steps that lead to higher cost efficiencies.
The process produces a silicon-rich proprietary anode material that can be used to replace graphite in Li-ion battery anodes, greatly improving their performance through silicon’s greater affinity for Lithium ions than graphite. The essential point, Bhogal says, is that the carbon provides a matrix to mitigate what would otherwise be unacceptable expansion of the silicon that would make its use impractical.
Bhogal adds that Nexeon’s first generation NSP-1 and second generation NSP-2 differ in ways they control the expansion of silicon and in the resulting performance enhancement they can provide. The older already established NSP-1 material can constitute up to around 10% of an anode while the newer NSP-2 can potentially provide much higher levels and provide an increase in energy density of almost 50% compared with a pure graphite alternative. He says that Nexeon has supplied NSP-2 “from a sampling perspective” to customers and to support joint development agreements.
Sourcing organic materials
But a key point from a sustainability perspective is how that activated carbon content is sourced. As Bhogal explains activated carbon “can be produced from either organic or inorganic materials” with the source of the former being some form of vegetation and that of the latter from the petrochemical industry. “There is a well-established process for producing activated carbon from the petrochemical industry,” he adds. “But that is obviously not very sustainable.” Therefore, the hunt is on for organic sources of activated carbon and Nexeon, Bhogal confirms, is thinking in those terms.
Beyond that is the issue of whether battery materials can be formulated to enhance not just their end performance in use but also the efficiency with which they can be reprocessed, whether for re-use or environmentally benign disposal at the end of their working life. Again, Bhogal indicates this is a current concern. “We are doing more than just thinking about end-of-use processing,” he confirms. “We are working and building on creating traceability of the end-to-end lifecycle of our product and the materials”.
But, as Bhogal also concedes, perhaps the key difference between the ‘front-end’ sustainability issues centred around performance and those at the ‘back-end’ concerning end-of-use reprocessing is that of the immediacy of their urgency. The first is already a daily priority. The second given that the use of EVs is still in a ramp-up stage with maybe a decade of more of use of vehicles with current generation materials and technology still ahead is more distant. As Bhogal puts it: “We’re working with customers to fully understand how to integrate our product in their ‘end of life’ product lifecycle and roadmap sustainability initiatives.”