Cathode material and process

A method of increasing the differential scanning calorimetry onset temperature of a lithium nickel oxide cathode material, the method comprising:

• (a) contacting particulate lithium nickel oxide cathode material with a treatment solution comprising aluminium ions and optionally lithium ions to provide a treatment slurry;
• (b) drying the treatment slurry to provide an intermediate treated material;
• and
• (c) calcining the intermediate treated material to provide an enriched lithium nickel oxide cathode material comprising (i) a core comprising a plurality of grains and (ii) enriched regions at the surface of the core and at the grain boundaries within the core, the
• enriched regions comprising a higher concentration of aluminium than the core, wherein the amount of aluminium ions included in the treatment solution is selected to provide 0.8 to 5.5 wt% aluminium based on the weight of metals in the lithium nickel oxide cathode material to be treated, excluding lithium.