Evolution of Performance of Nickel-Rich Cathode Materials in Contact with Ambient Air

Nickel-rich layered oxides are currently the preferred cathode active materials (CAMs) for lithium-ion batteries. However, the performance of CAMs is known to degrade when they are stored in ambient air due to surface reactions of the material containing residual lithium ions with atmospheric moisture and carbon dioxide to form lithium hydroxide and lithium carbonate. The residual lithium compounds on the CAM surface increase manifold upon long-term storage in contact with the atmosphere (ambient storage), with an attendant degradation of the electrochemical performance properties of the CAM, in particular, a 25% decline in specific discharge capacity at 0.1 C current density and a 50% decline at 1 C current density. New methods are proposed for the regenerating calcination of CAMs that have been stored in contact with air, and the addition of supplementary amounts of LiOH helps to achieve the highest capacitive characteristics of stored and then regenerated CAMs.