Improving the electrochemical performance of LiNi0.7Mn0.3O2 cathode material by CeO2 coating via Ce doping

Abstract

This study presents a novel strategy for constructing a stable cathode material by modifying LiNi0.7Mn0.3O2 (NM73) with CeO2 to address the issues of interfacial degradation and significant capacity decay during cycling of Co-free materials. In this approach, Ce3+/Ce4+ is doped within the NM73 bulk material, while CeO2 is coated on the surface of the bulk material to suppress the attack of electrolyte on the particle surface during cycling. As a result, the modified sample, Ce/NM-1.0, exhibits excellent cycling performance compared to the bare sample, NM73, with an initial discharge capacity of 181.7 mAh/g at a rate of 1C within the voltage range of 2.7 V–4.3 V, which is significantly higher than that of NM73 (164.7 mAh/g). Notably, the capacity retention rate of Ce/NM-1.0 after 200 cycles is 85.36%, whereas that of NM73 is only 78.93%. These results demonstrate that the strategy significantly improves the electrochemical performance and cycle stability of the modified material.X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy characterizations indicate that the excellent discharge specific capacity is attributed to the Ce ions doping, while the excellent structural stability is attributed to the CeO2 coating on the particle surface. This work provides valuable insights into the modification of other cathode materials to promote their commercialization.