Polydopamine-assisted coating layer of a fast Li-ion conductor Li6.25La3Zr2Al0.25O12 on Ni-rich cathodes for Li-ion batteries

Abstract

Ni-rich cathode materials have promising applications in lithium-ion batteries owing to their high energy density and reasonable cost. The surface stabilization of these materials is vital for achieving excellent electrochemical performance. In this study, a fast ionic conductor, Li6.25La3Zr2Al0.25O12 (LLZAO), was successfully coated on the surface of LiNi(0.88)Co(0.0)5Mn(0.07)O(2 )(LNCM) using a polydopamine (PDA) modification method. The abundant catechol groups of the intermediate PDA layer on the Ni0.88Co0.05Mn0.07(OH)2 (NCM(OH)2) precursor attracted metal ions in an aqueous solution, and a uniform LLZAO coating layer was formed after calcination under an O2 flow. The presence of the LLZAO protective film on the surface of LNCM was confirmed using several charac-terization techniques. The LLZAO-coated LNCM exhibited superior electrochemical properties compared to those of the pristine LNCM. Moreover, the LLZAO-coated LNCM demonstrated excellent electrochemical stability even at a high temperature (60 celcius). The deterioration of the surface structure of LNCM was significantly suppressed by the formation of the LLZAO coating layer, and LLZAO improved the Li+ ion transport at the electrode/electrolyte interface.