Enhanced Li Storage Performance of LiNi_(0.5)Mn_(1.5)O4-Coated 0.4Li2MnO3·0.6LiNi_(1/3)Co_(1/3)Mn_(1/3)O2 Cathode Materials for Li-Ion Batteries

摘要

In this study, Li-rich cathode, 0.4Li2MnO3· 0.6LiNi_(1/3)Co_(1/3)Mn_(1/3)O2 was synthesized by a resorcinol formaldehyde assisted sol—gel method for the first time. Then, the surface of the as-prepared Li-rich cathode was modified with different amounts of LiNi_(0.5)Mn_(1.5)O4 (5, 10, and 20 wt %) through a simple dip-dry approach. The structural and electrochemical characterizations revealed that the spinel LiNi_(0.5)Mn_(1.5)O4 coating not only can prevent electrolytes from eroding the Li-rich core but also can facilitate fast lithium ion transportation. As a result, the 20 wt % coated sample delivered an initial discharge capacity of 298.6 mAh g~(-1) with a Coulombic efficiency of 84.8%, compared to 281.1 mAh g~(-1) and 70.2%, respectively, for the bare sample. Particularly, the coated sample demonstrates a Li storage capacity of 170.7 mAh g~(-1) and capacity retention of 94.4% after 100 cycles at a high rate of 5 C (1250 mA g~(-1)), showing a prospect for practical lithium battery applications. More significantly, the synthetic method proposed in this work is facile and low-cost and possibly could be adopted for large-scale production of surface-modified cathode materials.