Insights into Enhanced Cycling and Rate Stability of LiNi0.88Co0.09Al0.03O2 via Co-doping for Lithium-Ion Batteries

Abstract

Ni-rich-layered structure cathode materials are receiving great attention in the next-generation lithium-ion batteries due to their high specific capacity and energy density. However, the poor cycle and rate capability of the materials, caused by the instability of structures, are limiting their applications. In this work, we provide a co-doping method to address the above issue for Ni-rich LiNi0.88Co0.09Al0.03O2 cathodes, which greatly improves the structural stability due to the suppression of the phase transformation from the layered to NiO-like (rocksalt) phase. Consequently, the parasitic reaction of the interface is abated. Based on our method, the co-doped Li(Ni0.88Co0.09Al0.03)0.98Cr0.01Mo0.01O2 shows the excellent capacity retention, ∼89.2% (174.3 mA h/g) with a current density of 100 mA/g after 200 cycles, much higher than that of the pure LiNi0.88Co0.09Al0.03O2, only remaining 75.2 mA h/g (about 35.4% capacity retention). In addition, the rate retention of Li(Ni0.88Co0.09Al0.03)0.98Cr0.01Mo0.01O2 also demonstrates the superior stability (92.1, 90.2, 86.2, and 77.6% at 100, 200, 400, and 1000 mA/g) with improving the electrochemical kinetics of materials. This work provides a feasible path to improve the electrochemical behaviors of Ni-rich-layered structure cathodes via heteroatom co-doping.