Surface modification of rare earth elements to enhance the electrochemical stability of Ni-rich Co-free cathodes

The Ni-rich Co-free cathode materials are considered the most optimistic choice for the long-term economic development of lithium-ion batteries (LIBs) due to the limited supply and high prices of cobalt. In this study, a uniform samarium oxide (Sm2O3) layer was coated on the surface of LiNi0.8Mn0.17Fe0.03O2 (NMF) cathode materials through wet subsequent heat treatment. Compared with the unmodified cathode materials, the modified cathode materials exhibit better electrochemical performance at high voltage. The specific discharge capacity of the modified cathode materials increased from 37.5 mAh g−1 (NMF) to 118.2 mAh g−1 after 200 cycles at 1 C and the retention rate increased from 21.18% to 69.77%. The samarium oxide coating effectively inhibits the reaction between the cathode materials and the electrolyte. Therefore, our study proposes a simple and scalable method for modifying nickel-rich cobalt-free cathode materials.