Effect of Residual Lithium Rearrangement on Ni‐rich Layered Oxide Cathodes for Lithium‐Ion Batteries

Abstract A water washing process can effectively reduce the presence of residual lithium with minimal effect on lithium‐ion battery cell performance. We investigated the effects of varying the amount of water used for washing and the temperature used to evaporate the water on Li 1.00 Ni 0.80 Co 0.15 Mn 0.05 O 2 . The residual lithium decreased and the cell performance deteriorated as the amount of water used for washing was increased from 0.7 to 5 times the amount of active material. The temperature at which the active material was dried after washing had a considerable effect on the reformation of the residual lithium layer after heat treatment. A ratio of water/active material of 1:1 and a drying temperature of 120 °C were selected as the optimal washing conditions, achieving a residual lithium content of less than 1000 ppm with minimum deterioration in cell performance; as a result of the treatment, the total volume of gas evolution was reduced by 25 %.