2 co-modified LiNi 0.6Co 0.2Mn 0.2O 2 cathode materials with enhanced electrochemical performance under harsh conditions]]>

摘要

The electrochemical properties of LiNi0.6Co0.2Mn0.2O2, such as cycling stability, rate capacity and coulomb efficiency, are not fairly well at large rate, high cutoff voltage and elevated temperature. In this article, a uniform nanoscale graphene@TiO2coating layer is skillfully formed on the surface of LiNi0.6Co0.2Mn0.2O2via an artful sol-gel-based method. The rGO@TiO2layer is evidenced by a series of detections, and the structures of the pristine and coated materials are investigated in detail. It indicates that the graphene@TiO2layer with a thickness of ～2?nm is uniformly covered on the LiNi0.6Co0.2Mn0.2O2particles. The “synergistic effects” of graphene@TiO2composite plays an important role in improving the comprehensive electrochemical performances of the cathode material. Compared with the pristine material, the graphene@TiO2co-modified LiNi0.6Co0.2Mn0.2O2shows enhanced electrochemical performances at large rate, elevated temperature, and high cutoff voltage. Particularly, it displays capacity retentions of 93.7% and 89.2% after 150 cycles at 1?C and 2?C, respectively, over 3.0–4.5?V. Even at high temperature of 55?°C and upper operating voltage of 4.5?V, the capacity retention of graphene@TiO2-coated sample increases almost 50% compared with the pristine sample after 150 cycles.