Rational Design of Multifunctional Surface Modification for Ni-Rich Layered Cathodes of Lithium-Ion Batteries

Although Ni-rich layered oxide materials (LNCMs) have received increasing attention as advanced cathode materials, their short lifespan constitutes a major limitation. In this work, we incorporate Ti- and B-functionalized cathode–electrolyte interphase (CEI) layers at the interface of LNCM cathodes via a simple one-step thermal process with boric acid (H₃BO₃) and titanium dioxide (TiO₂). It is discovered that coating TiO₂ increases the mechanical strength of LNCM cathode materials, effectively suppressing the microcracking of LNCM cathode particles. Furthermore, H₃BO₃ can react with residual lithium remaining at the LNCM cathode surface, which also leads to a decrease in the internal pressure of the cell and a minimization of reduction of ionic conductivity as CEI layers are formed at the LNCM interfaces. The incorporation of Ti- and B-functionalized CEI layers exhibits a synergistic effect, preventing undesired reactions and improving the surface stability of the LNCM cathodes. In the lifespan, the 0.75 wt % Ti- and B-functionalized LNCM cathode exhibits a 21.9%p increase in retention compared to LNCM cathodes after 100 cycles, even at high temperature. Postmodern analyses of cycled LNCM cathodes, including (cross-sectional) SEM, EIS, XPS, and ICP-MS, demonstrate that bifunctionalized LNCM cathodes reveal improved particle strength and markable suppression of electrolyte decomposition.