Surface protection of NMC811 cathode material via ZnSnO3 perovskite film for enhanced electrochemical performance in rechargeable Li-ion batteries

Abstract

In order to achieve the maximum utilization of Ni-rich cathode materials in the next generation Li-ion batteries, a new perovskite-type ZnSnO3 (ZTO) film was prepared on the surface of LiNi0.8Mn0.1Co0.1O2 particles via an in-situ co-precipitation method at a low annealing temperature. The changes in the crystallographic and functional properties were investigated via XRD and FTIR instruments. The formation of the core-shell structure was confirmed through surface inspection techniques such as FESEM/EDS and XPS. Fitting of O 1s spectra revealed more oxygen vacancies on the surface of ZTO@NMC811 than pristine NMC811 sample. The electrochemical cycling tests revealed that ZnSnO3-coated NMC811 delivered the highest charge and discharge capacities of about 223 and 202 mAhg−1 after first cycle. Furthermore, the surface modified NMC811 showed higher rate capability performance, maintaining about 73% of its initial capacity after re-cycling at 0.1C between cycle no. 25 and 30. The enhanced electronic and ionic conduction after ZnSnO3 film coating was certified by the significant decrease in Ohmic (Rs) and charge transfer (Rct) resistances before and after cycling. The improved cyclability and reversibility could be attributed to the protective role of the ZnSnO3 layer in preserving the layered crystal structure by suppressing side reactions between the active materials and electrolyte.