Enhancing cycle life of LiNi0.95Co0.04Mn0.01O2 cathode by bulk W-doping and surface Co-doping

Abstract

LiNi0.95Co0.04Mn0.01O2 cathode material is modified by bulk W-doping and surface Co-doping through a scalable co-precipitation-calcination process. A small amount of the dopants has no negative impact on specific capacity of the ultrahigh-Ni cathode, but significantly improves the structural stability and electrochemical performance. The modified sample delivers an initial discharge capacity of 228.3 mAh g−1 at 0.1 C (1 C = 220 mA g−1) and exhibits a capacity retention of 84.7 % after 300 cycles at a current density of 2 C and excellent rate capability (188.6 mAh g−1 at 5 C), demonstrating its practicability in high-energy-density lithium-ion batteries. X-ray photoelectron spectroscopy result shows that the collaborative modification can maintain a high Ni3+ content on the surface of the material. Furthermore, differential capacity analysis and electrode kinetic study suggest that the increase of polarization during cycling is suppressed and the structural stability is improved.