In-situ construction protective layer and phosphate doping synergistically improve the long-term cycle stability of LiNi0.6Co0.1Mn0.3O2

Abstract Ni-rich layered cathodes LiNixCoyMn1-x-yO2 (x ≥ 0.6) with high capacity and low manufacturing cost have aroused widespread concern. However, the surface/interface instability and structural degradation can reduce their service life. Aiming at modifying the electrochemical performance of Nickel rich NCM via introducing oxygen defects as well as forming protective coating layers, herein, a wet grinding procedure was explored to treat the mixture of NCM613 and a small amount of the phosphorus precursor NaH2PO2 following by a low-temperature calcination. The results indicate that the modified samples possess the rock salt/spinel phase coating layer and PO43− doping, which synergistically improve the cycle stability and rate performance of NCM613. After 500 cycles at 1C (2.8–4.5 V), the modified samples NCM613-0.3P and NCM613-0.6P show the retention of 81.5% and 85.9%, respectively. Even after 350 cycles at 5C, NCM613-0.6P exhibits an impressive capacity retention of 98.0%, extremely superior to the pristine NCM613 (25.7%). Moreover, for other Ni-rich layered cathode material (LiNi0.8Co0.1Mn0.1O2), such procedure can be applied successfully to improve the cycle stability. This work provides a useful modification strategy to enhance the stability of Ni-rich cathode materials.