Studies on stability and capacity for long-life cycle performance of Li(Ni_0.5Co_0.2Mn_0.3)O₂ by Mo modification for lithium-ion battery

Long-life property is one of the key factors for wide applications of lithium-ion batteries. Here, Mo-modified Ni-rich cathode material LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) is synthesized successfully via a solvent evaporating way followed with a calcination method. This strategy delivers two kinds of effects including Mo-doping and Mo-coating. Mo not only intercalates into the crystal lattice of NCM, but also forms a film-like coating layer on the surface to impede side reactions between electrode and electrolyte. Thus, its specific capacity, rate capability and cycle performance are improved simultaneously, especially in terms of long cycling life property. A series of physical and electrochemical characterizations are used to study the modified performance, and the sample with 1.0 wt% Mo modifying presents the best property with an approximate 3.5 nm coating layer surrounding the surface. Besides, the capacity retention ratio reaches to 89.7% even after 500 cycles between 3.0 and 4.3 V. However, Mo-modified samples have an obvious attenuation in the later period after charging to a higher voltage of 4.6 V although they have preferable cycle performance at the preliminary stage. The results indicate that the reaction mechanisms are diverse at different voltage ranges, which may guide subsequent researches.