Article originally posted on www.faraday.ac.uk
An Industry Sprint between Echion Technologies and the University of Birmingham has demonstrated the feasibility of direct recycling routes to efficiently recover, at high yield, Echion’s niobium-based anodes for fast-charging, high-power lithium-ion batteries. The electrochemical performance of cells made using the recovered material was almost identical to that of pristine materials. This represents an important step towards Echion integrating XNO® recovery into a closed-loop recycling process.
The battery recycling imperative
The case for recycling lithium-ion batteries at their end of life is compelling: it reduces waste, lowers the carbon footprint of battery manufacture, and retains material value. A nascent battery recycling industry is therefore emerging, deploying pyrometallurgical and hydrometallurgical techniques to retrieve critical minerals such as lithium, cobalt and nickel from today’s Li-ion batteries.
However, less is known about how best to recycle emerging high-performance batteries, such as those using Echion Technologies’ mixed-niobium oxide anodes (XNO®), which enable long-life, high-power Li-ion batteries that can be charged in about five minutes. The firm expects their anode materials to be deployed in batteries used in applications including mining trucks, AI data centres, industrial energy storage systems and high-performance motorsport.
Cambridge-based Echion had previously worked with materials chemist Professor Peter Slater at the University of Birmingham on a Faraday Institution Industry Fellowship to develop new XNO® materials. In a follow-on Industry Sprint – NORDIC – the team sought to discover ways to efficiently recover the high-value XNO® anode materials from both production scrap and test battery cells.
The opportunity for direct recycling
Echion has several motivations for pursuing recycling. Securing anode materials from recycled sources reduces the need to mine virgin niobium (niobium oxide costs around $45,000 to $60,000 per tonne) and could help stabilise or reduce product costs. The carbon footprint of recycled material may also be lower, and forthcoming EU regulations are expected to require cell manufacturers to use a proportion of recycled material in their batteries.
Echion is seeking to recover anode material not only from batteries that reach their end of life, but also from production scrap – such as offcuts from coated electrode rolls – which inevitably arise during manufacturing. Typically, around 5-10% of material is lost as scrap during cell production.
Conventional pyrometallurgical or hydrometallurgical recycling processes rely on high temperatures or strong acids to recover valuable elements such as lithium, cobalt, nickel, copper and manganese.
Ramon Cabiscol, Senior Process Engineer at Echion explains: "XNO® is very hard to dissolve in acid, which makes it difficult to process using conventional methods. However, this offers a good opportunity for ‘direct’ recycling – using milder processes to recover the anode material, typically by delaminating or stripping apart the binder and separating it from the metal current-collectors.”
Professor Peter Slater, Professor of Materials Chemistry, University of Birmingham, continues: "You’ve got this excellent XNO® material that performs really well, so you don’t want to lose that value during recycling. The aim is to minimise processing to recover the material, and regenerate it as closely as possible to its pristine condition.”
During the Sprint, researchers Aron Spiller and Alex Green applied Birmingham’s expertise in direct recycling, developed through the Faraday Institution’s ReLiB (Recycling and Reuse of EV Lithium-ion Batteries) project to the XNO® materials.
Cabiscol reflects on the collaboration: "Peter Slater’s group at Birmingham's School of Chemistry brings deep expertise in material processing, including of techniques we didn’t have in-house. The Sprint researchers worked very autonomously – at every meeting they brought new ideas, including approaches we hadn’t considered.”
Echion supplied both production scrap and used pouch cells to the Birmingham team. The researchers manually dismantled the cells to access the electrodes and investigated two recovery methods. The first – thermal delamination – involves decomposing the binder in an oven at high temperature. The second – ice stripping – was previously developed at Birmingham. Slater explains: "In ice stripping, you spray water onto the electrode, put it onto a cold plate that freezes the water, and then you can peel off the clean electrode.”
Using these techniques – both of which proved effective – the team achieved recovery yields of greater than 95% of the anode material.
Material recovered from end-of-life batteries required a short treatment to remove residual lithium. Echion then manufactured new cells using recovered XNO® and assessed their performance.
Cabiscol explains: "The electrochemical performance of cells (measured by specific capacity retention at low – 0.5C – and high – 10C – charging rates) made using the recovered material was very close to that of pristine material, and we retained the crystallographic structure of the XNO® after processing. The results were almost identical to pristine material, so in that sense the Sprint was a strong success.
Most of the techniques we explored used readily available equipment – such as ovens and widely available chemicals – and relatively gentle processing conditions. The recovered XNO® anodes are cost-competitive with mining niobium and producing new material."
The route ahead
A key next step is to apply the process to scrap material generated during battery manufacturing. While Echion’s raw anode materials are manufactured in Brazil in partnership with niobium-producer CBMM, batteries incorporating XNO® are manufactured by partners such as GUS Technology in Taiwan.
Challenges remain in scaling these techniques commercially. For example, in the Sprint, cells were dismantled manually to access the electrodes whereas a commercial process would likely involve shredding batteries followed by separation of electrode materials using magnetic or electrostatic methods.
Cabiscol explains why recycling from end-of-life batteries is a longer-term proposition: "XNO®-based batteries are not yet produced at full scale. In addition, most recyclers process mixed waste streams, combining many types of Li-ion batteries in a single process. Niobium-based anodes will remain a niche product for some time, so establishing a dedicated recycling route would require a coordinated network of partnerships with vehicle makers, cell makers and recyclers to bring together sufficient volumes of end-of-life batteries.
While recycling our material is a long-term objective of the company, this Sprint has shown that it is technically feasible."
