The Na-Y Co-modification Engineering of LiNi_0.8Co_0.1Mn_0.1O₂ with High Performances

Abstract

LiNi0.8Co0.1Mn0.1O2 (NCM811) is considered a cathode material with great commercial potential. However, Li/Ni mixing, residual lithium compounds, and side reaction limited the popularity of Ni-rich batteries. Thus, a simple strategy is employed to realize a comodification of Na+ and Y3+. As demonstrated in the XPS results, the residual lithium compounds (Li2CO3/LiOH) and side reaction products are inhibited. The capacity retention rate of the modified NCM811 is 86.4% after 300 cycles at 1C, 34.5% higher than that of the pristine. Na+ expands the space of the Li+ slab, thereby reducing the charge transfer resistance and inhibiting the mixed discharge of cations. Meanwhile, Y3+ decreased the lattice along c-axis to restrict the movement of cations (Ni2+) into the Li site, with improving the exchange of Li+. The formed LiYO2 coating layer restrains the direct contact between the electrolyte and the electrode material so that side reactions are inhibited, reducing the electrochemical resistance.