Characterisation, Dissolution and Recovery of Critical Materials in Lithium-ion Battery Cathodes

Lithium-ion batteries (LIB) are one of the most utilised form of electrochemical energy storage around the world. In recent years, the use of LIBs has extended from portable electronics into electric vehicles (EV). As the number of EVs on the road increases, recycling of these batteries must be addressed. Many of the materials utilised in these batteries have significant monetary and industry value. The cathodes used in commercial LIBs contain critical materials such as cobalt, nickel, manganese, and aluminium. Cobalt and nickel in particular are of the highest monetary value, but are also widely utilised in many industrial applications. Therefore, it is important that these cathode materials are effectively recovered in order to go back into LIBs or be a feedstock for other applications. This thesis covers the characterisation, dissolution, and recovery of LIB cathodes. Firstly, cathode composite structures are visualised through the use of multi-modal AFM imaging to understand the mechanical properties of the composite. Agglomeration of the binder and conductive carbon was revealed as the binding mechanism for the cathodes studied. This will feed into developing new methods for separation of cathode black mass from the current collectors. In addition, electrochemical dissolution of cathode metal oxides is studied. Selective dissolution using electrochemistry is explored in order to purify cathode waste streams by separation of different metals. This has been studied for several relevant cathode metal oxides in simple electrolytes. Selective dissolution of lithium from LCO and NMC was achieved, demonstrating the ability to purify waste streams of critical metals. Finally, recovery of two critical metals, nickel and cobalt, is reported. This has been done by electrodeposition of the two metals as an alloy. Deposition properties such as morphology and alloy composition have been studied as an effect of factors such as electrolyte additives, metal ratios, and current densities applied. This was done with model electrolyte solutions. Deposition from real leachates was also investigated, and good alloy deposits were obtained that have little influence from manganese present in solution.