Improved High-Potential Property of Ni-Rich LiNi0.8Co0.1Mn0.1O2 with a Garnet Ceramic LLZTO Surface Modification in Li-Ion Batteries

The Ni-rich LiNixCoyMn1–x–yO2 with high specific capacity and superior thermal stability under a high cutoff voltage (>4.3 V) will play a critical role in high-power lithium-ion batteries (LIBs). In this paper, LiNi0.8Co0.1Mn0.1O2 (NCM811) equipped with a stable garnet ceramic Li6.5La3Zr1.5Ta0.5O12 (LLZTO) nanoshell is successfully synthesized via a simple wet chemical approach. X-ray diffraction, scanning electron microscope (SEM), energy-dispersive spectrometer (EDS) element mapping, and transmission electron microscopy (TEM) confirm the presence of LLZTO on the NCM811 surface. The NCM811 with 2 wt % LLZTO (2-NCM811) can deliver a superior specific capacity of 144.4 mAh·g–1 at 1C (2.8–4.3 V) after 100 cycles, accompanied by a capacity retention rate as high as 81.1%. But pristine NCM811 has a discharge capacity of only 119.6 mAh·g–1 and a capacity retention rate as low as 69.5% under the same condition. What is more, 2-NCM811 exhibits an enhanced discharge capacity of 129.6 mAh·g–1 at 1C (2.8–4.5 V) after 100 cycles and a high capacity retention rate of 62.9%, which are superior to those of pristine NCM811 (110.0 mAh·g–1, 57.6%). The improved high-potential performance of 2-NCM811 can be attributed to the positive role of the LLZTO shell, which enhances the structural stability and simultaneously inhibits adverse side reactions at the surface of 2-NCM811 during cycling. Based on the above advantages, LLZTO with three-dimensional (3D) diffusion pathways and high ion conductivity is expected to be the most prospective material for the surface modification engineering of nickel-rich cathode materials in lithium-ion batteries (LIBs).