Critical roles of semi-conductive LaFeO3 coating in enhancing cycling stability and rate capability of 5 V LiNi0.5Mn1.5O4 cathode materials

Abstract

High-voltage LiNi0.5Mn1.5O4 has been considered as one of the most promising cathode candidate for LIBs due to its excellent energy density and power density, but the attack of HF on the material and dissolution of Mn ions into electrolyte can cause structure collapse and serious capacity fading of the cathode. In this work, a semiconductor of LaFeO3 was coated on the surface of polyhedral LiNi0.5Mn1.5O4 via a wet-chemical method. LaFeO3 coated at the surface of LiNi0.5Mn1.5O4 significantly protects the cathode from the corrosion of HF and alleviates the dissolution of Mn ions into organic liquid electrolyte during (dis)charge processes. The 2.0 wt% LaFeO3-coated LiNi0.5Mn1.5O4 cathode exhibits much better cycling stability, rate capability, and elevated temperature stability than the pristine: capacity retention of 97.71% at 1 C after 100 cycles vs. that of 90.96%; rate capability of 111.9 and 99.6 mAh g−1 at high C-rates of 5 C and 10 C vs. that of 90.6 and 76.4 mAh g−1, respectively; and high temperature capacity retention of 93.29% at 1 C after 100 cycles vs. that of 69.9%. Present study provides a facile method to mitigate the dissolution of Mn ions into electrolyte for LiNi0.5Mn1.5O4, resulting in excellent cycling performance and rate capability.