Trace Contaminant Induced Lattice Strain and Phase Instability in Recycled High-Nickel Cathodes
Trace impurities in recycled high-nickel cathodes induce lattice strain and microcracking, accelerating capacity fade and raising landed cost per cycle.
Li/Ni Mixing
Meaning
Atomic scale defects occur when lithium and nickel ions exchange positions within the crystal lattice of a cathode material. This li/ni mixing is a common challenge in the production of high nickel oxides because the two ions have nearly identical sizes. The presence of nickel in the lithium layer blocks the pathways required for efficient ion transport.
Disorder Type
Antisite defects represent the most frequent form of this structural confusion. Excessive li/ni mixing reduces the amount of lithium that can move in and out of the electrode. This physical blockage increases the internal resistance and slows down the charging process.
Performance Cost
Batteries with high levels of this defect show a noticeable drop in discharge capacity and voltage. Because li/ni mixing is irreversible, the damage to the energy density is permanent. This effect is one of the primary reasons for the difference between theoretical and actual battery performance.
Thermal Effect
Distorted lattices are less stable when the battery is fully charged. Minimizing li/ni mixing during the heating phase of production improves the safety profile of the final cell. Researchers focus on perfecting the oxygen flow and heating duration to keep the ions in their correct locations.