ISSUE 011 Autumn 2021 Candela C-7 hydrofoil speedboat dossier l In conversation: Robert Hoevers l Battery recycling focus l Vehicle dynamics insight l ZeroAvia hydrogen-electric aircraft digest l Motor materials

that the aluminium and copper foil current collectors have been effectively delaminated on both sides, leaving the foil relatively free from active material. The physical structure of both cathode and bulk anode materials are unaffected by the delamination process. However, the larger particles of graphite in the anode appear to have been ‘cleaned’ of smaller particles, most likely a carbon-black conductive additive. While the delamination will occur in de-ionised water, the efficiency of separation can be improved by adjusting the pH to etch the substrate, or by adding wetting agents to aid the collapse of the cavitation bubbles. While binder-specific solvents such as NMP also enable rapid delamination by partially dissolving the binder, this is probably not a viable practical option owing to its cost and toxicity. Solvents such as ethanol are unsuitable because of their volatility, lack of polymer solubility and their inability to support suitable cavitation. Depending on the choice of delaminating solvent, the delaminated active material will also contain the polymer binder. A significant proportion of battery waste material originates from production scrap with various polymers. These can be recovered with acetone to rebind the active materials to a substrate. This approach has shown recovery of 99.5% of active material for both the anode and cathode. At under 3 µm, the unrecovered 0.5% of active material comprises particles that are too small to be easily recovered using filtration techniques; an example here is an additive called carbon-black, which has particle sizes of 0.05-0.1 µm. This compares with about 67% efficiency when recovering cathode material using a stirred sulphuric acid solution. The delamination rate for both electrodes with ultrasound is 44 cm 2 /s, so the prototype unit is capable of processing 350 of the 20 x 20 cm electrodes per hour at a cost of $0.10-0.15/kg of electrode material. The ultrasonic delamination technique is designed to work on whole rather than shredded electrodes, which makes it particularly suitable for production scrap and quality control reject material, which accounts for about 5-20% of production. The challenge is that existing cell designs do not lend themselves to disassembly. However, this could be financially preferable to shredding, and produces higher purity products with a lower chemical and energy requirement. Many manufacturers are also designing cells that are easier to disassemble and recycle. This ultrasonic technique will become more significant when solid-state batteries need to be recycled, in about 10 years’ time. As the name suggests, the battery cells do not use a liquid electrolyte, instead they have a ceramic layer. An ultrasonic process may well be a key tool in separating these layers for quicker and more reliable recycling. All-in-one shredding New approaches are overcoming the challenges of having to disassemble a pack and even the cells by hand to get at the electrodes. Packs can be recycled directly, using a powerful shredding machine submerged in an ionic fluid. The packs are shredded in the fluid that discharges the pack as it is destroyed. The plastic shreds and copper foil float to the surface for Some suppliers of battery recycling services Belgium Umicore +32 2 225 71 11 www.umicore.com Canada Li-Cycle +1 877 542 9253 www.li-cycle.com Lithion +1 514 353 4008 www.lithionrecycling.com France Veolia +33 1 34 93 31 31 www.veolia.com Germany Accurec Recycling +49 2151 652 980 www.accurec.de Promesa +49 173 7228 118 www.promesa-tec.de Redux +49 69 8618 7300 www.redux-recycling.com USA American Manganese +1 778 574 4444 www.americanmanganeseinc.com Global Tech Environmental +1 800 770 2330 www.globaltechenvironmental.com A sonotrode speeds up the delamination of electrodes (Courtesy of University of Leicester) Autumn 2021 | E-Mobility Engineering 39 Focus | Battery recycling