Facilitating Lithium-Ion Diffusion in Layered Cathode Materials by Introducing Li^(+)/Ni^(2+) Antisite Defects for High-Rate Li-Ion Batteries

Li^(+)/Ni^(2+) antisite defects mainly resulting from their similar ionic radii in the layered nickel-rich cathode materials belong to one of cation disordering scenarios.They are commonly considered harmful to the electrochemical properties,so a minimum degree of cation disordering is usually desired.However,this study indicates that LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)as the key material for Tesla batteries possesses the highest rate capability when there is a minor degree(2.3%)of Li^(+)/Ni^(2+) antisite defects existing in its layered structure.By combining a theoretical calculation,the improvement mechanism is attributed to two effects to decrease the activation barrier for lithium migration:(1)the anchoring of a low fraction of high-valence Ni^(2+) ions in the Li slab pushes uphill the nearest Li^(+)ions and(2)the same fraction of low-valence Li^(+) ions in the Ni slab weakens the repulsive interaction to the Li^(+) ions at the saddle point.