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

recovery, while the rest sinks to the bottom. This creates a ‘black mass’ of all the different elements. The lithium can be recovered as lithium carbonate, while the cobalt and manganese are recovered as sulphates. These can be 97% pure and fed back as a cathode material precursor for building cells. With this all-in-one approach, a spoke-and-hub model with an all-in-one shredding technique allows all kinds of batteries – not just EV cells – to be easily recycled, as no disassembly is required. It takes all kinds of lithium-ion batteries, from packs used in power tools to EV packs, and produces the black mass that can be more easily shipped to the purification plants alongside those developing the precursor materials. Another patented approach is to immerse the shredded lithium-ion batteries in an organic solvent and then feed them into a dryer to produce a gaseous organic phase and dried battery residue. The resulting powder is fed into a magnetic separator to remove magnetic particles such as steel and iron from the pack, and then an eddy-current separator can be used to extract the aluminium and copper. Grinding the non-magnetic residue and mixing the fine particles with an acid produces a metal oxides slurry. Leaching this slurry and then filtering the leachate removes the non-leachable metals before feeding it into a sulphide precipitation tank. Mixing this leachate with an organic extraction solvent separates the cobalt and manganese using solvents and electrolysis, then crystallising sodium sulphate from the aqueous phase, adding sodium carbonate to the liquor and heating up the sodium carbonate to produce a precipitate of lithium carbonate. When dried, the lithium carbonate has a purity of 99% and is suitable as the starting point for new battery cells. As a final stage, the graphite can be purified from the non-leachable materials in a furnace operating at up to 800 C and combining the two recycling techniques. This also reduces the amount of effluent, but has an issue with power consumption for the furnace. This opens up new models for recycling the batteries. Conclusion Battery recycling has a wide range of challenges, not just in the process to recover the precious lithium and other elements. Re-using the cells in other applications leads to additional requirements for BMSs, and spreads out the packs across wider areas in homes, offices and wind and solar farms. This also presents challenges for how the battery packs are eventually recycled. While car makers may have more of a closed-loop approach to taking exhausted packs from vehicles and recycling them, the increased adoption of second-use applications presents more transport challenges for the packs. This is leading recycling firms to develop hub-and-spoke models, where the shredding of packs can be performed more locally, avoiding the challenges and safety issues of transporting exhausted packs. This means the ‘black mass’ of recycled material can be easily and safely shipped to the cathode- making plants as a precursor material. However, the focus on new recycling processes may well become more significant with the advent of solid-state batteries that need to be recycled. Acknowledgements The author would like to thank Kunal Phalpher at Li-Cycle and Chunhong Lei at the University of Leicester and the Faraday Institution for their help with the research for this article. Focus | Battery recycling An all-in-one battery pack recycling process results in the production of this ‘black mass’ (Courtesy of Li-Cycle) 40 Autumn 2021 | E-Mobility Engineering