Boosting Electrochemical Performances of Li-Rich Mn-Based Cathode Materials by La Doping via Enhanced Structural Stability

La-doped Li1.2Ni0.13Mn0.54Co0.13O2 cathode materials were successfully synthesized by the sol-gel method. The structure, morphology, element valence states, cyclic voltammetry, and cyclic properties were characterized to investigate the properties of the synthesized materials. The as-prepared La-doped Li1.2Ni0.13Mn0.54Co0.13O2 materials exhibit well the crystalline hexagonal layered structures with lamellar-like particles featuring a rough surface. The optimal sample, designated as LLRMO-2 with 1/100 La3+ doping, delivers an impressive discharge capacity of 271.2 mAh g−1 with a capacity retention of 87.8% after 100 cycles at the current density of 100 mA g−1 compared with that of 203.5 mAh g−1 with only 110.6 mAh g−1 after 100 cycles for the pristine sample. Furthermore, the LLRMO-2 cathode exhibits a superior rate capability compared to the pristine sample and shows excellent cyclic performances with the capacity retention of 48.1% after 400 cycles. The voltage decay per cycle is only 1.60 mV, which is less than 3.70 mV of the pristine one. The enhanced capacity, rate capability, and cyclic performance observed in the La-doped Li-rich layered cathode can be attributed to the improved structural stability as well as the higher diffusion coefficient of lithium ions. These results suggest that the strategy of introducing La3+ into the transition metal slabs is an efficient approach for boosting electrochemical performances of Li-rich Mn-based cathode materials via enhancing structural stability.