All materials were characterised prior to and after leaching using a Bruker D8/ Panalytical Empyrean powder diffractometer (Cu Kα radiation) operating in reflection mode or Bruker D2 diffractometer (Co Kα radiation). Variable temperature-powder x-ray diffraction (VT-PXRD) measurements were conducted using a D8 diffractometer fitted with an Anton Parr heating stage. Rietveld refinements were carried out using the GSAS suite of programs. XRF analysis was conducted using a Bruker S8 Tiger (best detection mode). SEM-EDX analysis was conducted using a Hitachi TM4000plus benchtop SEM with AztecOne EDX analyser. Chemical compositions of ascorbic acid leachates and digested cathode material were determined by ICP-OES (5110, Agilent). Solid cathode materials (before and after NaOH bath and ascorbic acid leaching) were microwave digested (Milestone Ethos Up MA182) in aqua regia. Standards were prepared using a multi-element standard (1000 g/l, Certipur®). STEM-EDX measurements for the timed study samples were prepared from the dried residue bulk by grinding in an agate mortar and further dispersal between two glass slides. The powdered samples were deposited on TEM holey-carbon Cu grids and imaged using a JEOL JEM-2100+ microscope at 200 keV in STEM mode. The EDS maps were collected for approximately 10 minutes each using an Oxford Instruments EDAX EDS detector. Electrochemical testing of cathode materials was carried out in coin or Swagelok TM cells. For coin cell assembly, electrode slurries were prepared by mixing the cathode material, carbon black, PVDF in a ratio of 90:5:5. The solid components were mixed with 1-methyl-pyrrolidinone (NMP) before coating onto aluminium foil and drying at 80°C. Coatings were dried overnight at 110°C. Before assembly of coin cells, NMC532 materials were calendared at 80°C to a porosity of 30-35%. 15 mm circular disks were cut out of the electrode before assembling 2032 type coin cells. Finally, coin cells were assembled using the cut out electrodes, separator (WhatmanTM GF/C glass microfibre), electrolyte (1M LiPF6 in ethylene carbonate and dimethyl carbonate 50/50 (v/v)) and lithium metal anode. To prepare Swagelok TM cells, layered oxide cathode powders and carbon black (dried overnight at 110°C) were ground together in a glovebox. Swagelok TM cells were assembled using the ground cathode/carbon black, separator (Whatman TM grade GF/D glass microfibre), electrolyte (1M LiPF6 in ethylene carbonate and dimethyl carbonate 50/50 (v/v)) and lithium metal anode. Coin and Swagelok TM cells were testing using a BioLogic BCS-805 system.