On the afternoon of Monday, 6th July, the Royal Society of Chemistry’s Applied Materials Chemistry Interest Group hosted a summer webinar entitled ‘Challenges in the Recycling of Lithium-ion Batteries’. The webinar’s aim was to discuss the current waste and recycling industry approach for batteries, share information on the latest research in lithium-ion battery recycling and to define challenges in the field for researchers to adopt in the pursuit of a greener future. The event began with an introduction and overview of the RSC’s Applied Materials Chemistry Group by Edward Randviir of Manchester Metropolitan University, who also chaired the event.
There were three formal presentations and the webinar began with ‘Battery Raw Materials Challenges and Opportunities’ by Dr Evi Petavratzi of the British Geological Society (BGS), which is the world’s oldest national geological survey. She began by discussing climate change and the way it was driving the global transition to electric vehicles (EV). The development of lithium-ion battery technology was shown and the potential energy density improvements with solid state batteries were highlighted. There would be huge increases in demand for both lithium and cobalt by 2030. For example, cobalt production would need to double to meet predicted global EV demand and lithium and graphite production would need to triple over the same period. Raw material supplies would thus have to be rapidly ramped up. The current sources of lithium, cobalt, nickel and graphite production were concentrated in just a few countries, with recycling contributing very little. Twenty-two of the thirty-nine cobalt refineries were in China, which meant that there was a major cobalt transport route from the Democratic Republic of the Congo to China. The local challenges, such as the impact of mineral extraction on the environment, were then reviewed. The different timelines between new vehicle production and mineral source development meant that it took much longer to produce supplies of the critical metals needed than it did to introduce a new car.
Dr Petavratzi then moved on to discuss what she called the ‘myths of recycling’, which included the belief that supply issues could be mitigated by recycling. Unfortunately, the challenges of battery recycling meant that there would be major limitations in what could be achieved without innovative, more efficient and lower cost recycling processes. To meet future EV-battery material supply demands, new mines, refineries and production lines would be needed in addition to recycling.
The second presentation was from Dr Linda Gaines, Chief Scientist at Argonne National Laboratory, Illinois, USA. She was working with the RECELL (Advanced Battery Recycling) Centre, which was part of the DOE’s critical raw materials plan aiming to reduce, or eliminate, the USA’s reliance on these materials and to decrease the cost of battery recycling. Dr Gaines then discussed the lithium-ion battery lifecycle and gave the example of the Umicore pyro- and hydro-metallurgical recycling process which was operating in Belgium with a 7,000 metric tonnes per annum capability. The recovered materials did not have the ‘organised structure’ that was needed for battery production, so a more direct recycling approach was preferable and the levels of waste could be reduced. This was a key interest at RECELL.
The RECELL centre has four focus areas; these are direct cathode recycling, design for recycling, modelling and analysis and other material recycling. There are already many known pathways for recycling batteries, so these are being modelled across the supply chain to give a view of how well they performed. Factors assessed included cost, energy use and emissions, among others. Again, the significant level of Chinese cobalt refining was emphasised. The material complexity of lithium-ion batteries was demonstrated; this mixture needed to be separated if efficient recycling was to be achieved.
There were also many stages in the recycling process, but it typically began with shredding, although this often generated fine anode and cathode particles that could contaminate the other materials. RECELL had investigated solvent-based separation processes and they had looked at froth floatation techniques using kerosene to isolate the different materials found in lithium iron phosphate (LFP) and lithium nickel manganese cobalt oxide (NCM111) battery types. Solvent extraction had additionally been used to separate the binders. The aim was to combine several suitable processes capable of leaving a separated cathode that could be reused. However, older cathodes could be inferior and needed re-lithiation to recover their performance. Various processes had been evaluated and a key challenge was to develop a low cost economically viable process. RECELL were also looking at the possibility of rejuvenating batteries to extend their life. This approach used a rinsing process to clean the cathode surfaces. The main recycling challenge was summarised as being able to obtain value from a 10 year old lithium-ion battery, irrespective of the specific type of chemistry.
The final presentation was by Professor Andy Abbot from the University of Leicester and was titled ‘Designing Batteries for Recycle’. Andy began by using the example of traditional lead acid batteries, which were very efficiently recycled and then moved on to discuss the key design elements needed for implementation of circular economy approaches. A key requirement was to minimise the number of components used; the opposite of what was currently the case with lithium-ion batteries! Andy showed a breakdown of the disparate range of materials found in these batteries. He then looked at the predicted rapid growth in the global number of EVs; there could be as many as 530 million by 2040, up from 3 million in 2017.
The separation techniques that could be used in battery recycling were listed, but the large number of materials made any separation process very complex. Andy was investigating the possibility of using robots to disassemble batteries in a collaborative project called ReLiB. There was a significant capacity challenge emerging as there could be up to 500 tonnes per day of batteries arising for recycling in the UK by 2030. Battery packs were difficult to open; there were numerous glues, clips, and screws etc and some could take two hours or more to dismantle. Disassembly would be made easier if water soluble glues were used. These factors explained why pyrometallurgical methods were currently used, but they were expensive, requiring a gate fee, and up to 50% of the metals were lost.
A cheaper approach was to use solvo-metallurgy and a basic route was outlined. The Chinese already had a plant using such a process and it was thought to have opened earlier in 2020. The challenges of the solvent-based approaches were detailed and the important parameters and properties were reviewed. In the ReLiB project, a water and mechano-assisted delamination process had been demonstrated and it was much faster than a chemical process. An automated cell assembly method would help and this had been demonstrated in the USA.
Overall, using ‘Design for Recycle’ approaches could bring significant additional benefits, e.g. standardisation of connectors and the positioning of anodes and cathodes at each end of the cell in a so called ‘Christmas cracker’ design that made dismantling easier. Life cycle analysis had confirmed the need for low cost recycling processes, especially as the cost of batteries was continuing to fall. This meant using common, low cost chemicals and solvo-mechanical processes looked promising. The current pyro- and hydro-metallurgical routes also gained no value from the plastics, carbon and other materials and the best approach was to be able to recover materials directly in a form where they could be reused in batteries, i.e. with high value. Andy concluded by stating that battery recycling needed to be scaled up rapidly to cope with the expected increased demand for EVs.
In summary, this was a very useful and interesting webinar, which highlighted both the potential benefits and challenges around the recycling and reuse of key materials from end of life electric vehicle lithium-ion batteries. However, it was quite clear that recycling will only ever be a part of the battery raw material supply solution and that, in order to meet the expected growth in demand, there will also need to be a significant expansion in mining and other primary extraction routes.
Written by Martin Goosey, Envaqua Research Ltd