Excellent rate capability and cycling stability in Li+-conductive Li2SnO3 -coated LiNi0.5Mn1.5O4 cathode materials for lithium-ion batteries

摘要

High-voltage LiNi0.5Mn1.5O4 is a promising cathode candidate for lithium-ion batteries (LIBs) due to its considerable energy density and power density, but the material generally undergoes serious capacity fading caused by side reactions between the active material and organic electrolyte. In this work, Li+-conductive Li2SnO3 was coated on the surface of LiNi0.5Mn1.5O4 to protect the cathode against the attack of HF, mitigate the dissolution of Mn ions during cycling and improve the Li+ diffusion coefficient of the materials. Remarkable improvement in cycling stability and rate performance has been achieved in Li2SnO3-coated LiNi0.5Mn1.5O4. The 1.0 wt%Li2SnO3-coated LiNi0.5Mn1.5O4 cathode exhibits excellent cycling stability with a capacity retention of 88.2% after 150 cycles at 0.1 C and rate capability at high discharge rates of 5 C and 10 C, presenting discharge capacities of 119.5 and 112.2 mAh g(-1), respectively. In particular, a significant improvement in cycling stability at 55 degrees C is obtained after the coating of 1.0 wt% Li2SnO3 , giving a capacity retention of 86.8% after 150 cycles at 1 C and 55 degrees C. The present study provides a significant insight into the effective protection of Li-conductive coating materials for a high-voltage LiNi0.5Mn1.5O4 cathode material.