Surface stabilized Ni-rich LiNi0.9Co0.08Al0.02O2 cathode materials via surface modification with GdPO4 for lithium-ion batteries

Ni-rich LiNixCoyAl1-x-yO2 (NCA) with high energy density and relatively low cost is a promising candidate. However, interfacial instability and severe kinetic hindrance lead to severe property fading and serious safety concerns during the prolonged Li+ intercalation. Herein, we introduce an effective inorganic coating strategy for gadolinium phosphate (GdPO4) surface modified NCA cathode material by a sample wet-chemical method, which enhance the layered structural stability, lower the lithium migration barrier. As a result, superior rate capacity and stable capacity retention for NCA are exhibited after GdPO4 coating. Especially for 3 wt% GdPO4 coated sample, the first discharge capacity is 102.7 mA h g-1 at 5C, as well as capacity retention of 85% after 100 cycles. The improved electrochemical performance turns out to be uniform and thin coating layer by transmission electron microscope, the decreased voltage polarization by cyclic voltammetry, as well as the resistance changes between the cathode and solid electrolyte by electrochemical impedance spectroscopy. Taking all these findings into account, it is evident that GdPO4-coated Ni-rich cathode material can be utilized in advanced lithium-ion batteries.