A number of variables were refined in order to optimise the leaching process. The optimum concentration of ascorbic acid was identified as 1.25M; complete successful leaching of the spinel phase required that the pH of the solution must be as low as 0. This is consistent with the relative stabilities of transition metals in solution as Mn 2+ is the most stable oxidation state for Mn in acidic media). In addition, lower concentrations suffered from reproducibility issues. The maximum solid:solution ratio using 1.25M ascorbic acid was found to be 1:20 (i.e. 1 g in 20 ml) with 10 minutes needed to leach the spinel phase fully (Figure ). Increasing the cathode material mass further caused an insoluble orange precipitate to form after treatment. The presence of such a precipitate would cause issues during the regeneration step. Therefore, the following conditions were established for reproducible leaching of spinel from the cathode material: 1.25M, 70°C, 10ml of acid, 0.5g of cathode material after Al dissolution (solid to liquid ratio of 1:20), 10 minutes. This quick and efficient removal of the low value spinel allows for the remaining cathode material to undergo direct regeneration. Similar studies have been attempted with inorganic acids but led to extensive delithiation of the remaining layered oxide.