Recycling of Lithium-ion Batteries

The electrification of transport is a major goal of the UK government to combat climate change. Consequently, the demand for lithium-ion batteries (LIBs) in electric vehicles has increased and is predicted to increase in the coming years. Currently, recycling is seen as an end-of-pipe process in which valuable materials are down-cycled and leave the supply chain. This necessitates a circular economy model whilst the scale of end-of-life (EoL) batteries is still manageable, to prevent a build-up of hazardous waste. Using retro-economic analysis, it was found that the cost of LIB recycling should be in the range of $2-6 /kg of battery to enable profit and allow processing without gate fees. A techno-economic assessment showed that this is possible with hydrometallurgical processing of EoL materials. Disassembly of the material prior to processing, rather than shredding, contributed to greater cost savings (40-80 %) in comparison to using virgin materials ( < 20 %). The main barrier to recycling was therefore identified as disassembly, in which lack of standardisation and safety issues renders the process slow and difficult. A process that enabled the rapid delamination (< 5 s) of electrode active material (AM) from metal foil current collectors was developed using high-powered ultrasound on electrodes that were uncycled or EoL. Particle size was determined to be the most crucial factor in AM adhesion to the current collector, in which it was easier to delaminate the larger anode particles than the smaller cathode particles. Increased PVDF crystallinity in the EoL anodes also increased the AM adhesive strength compared to the uncycled anodes, resulting in more force required for delamination. Finally, the recovery of the black mass from the cathode was investigated, producing a LIB precursor that could be reformulated into cathode active materials that are currently being used in industry. This was done using a deep eutectic solvent consisting of oxalic acid dihydrate and choline chloride, in which selectivity for manganese and cobalt over nickel was observed during dissolution. Cobalt and manganese oxalates were coprecipitated via the addition of water, in which nickel remained in the leachate and could be recovered by filtration.