Benefiting from high energy density and low cost, Ni-rich LiNi_xCo_yMn/Al_1–x–yO₂ materials have re-ceived a great attention as promising cathode candidates for next-generation high-energy lithium-ion bat-teries (LIBs) that are widely used in electric vehicles (EVs). However, with an increased Ni content, Ni-rich cathode materials suffers from severe structural, chemical, and mechanical instabilities, seriously re-stricting their industrially safe application in power LIBs of EVs. In this review, primarily, the synthesis methods of Ni-rich cathode materials are summarized in detail, which contain solid-state method, sol-gel method, hydrothermal method, spray-drying method, and co-precipitation method. Subsequently, the key failure mechanisms, including ion mixing and irreversible phase transition, residual Li species and inter-face side reactions, mechanical microcracks, and transition metal dissolutions, were thoroughly analyzed throughout the preparation, storage, and service of Ni-rich cathode materials, thereby clarifying various performance decay behaviors of materials. The modification strategies that cover ion doping, surface coating, core-shell/gradient materials, and single-crystal materials are systematically discussed for Ni-rich cathode materials, aiming at presenting conspicuous research progresses and current shortcomings for the stabilization of Ni-rich cathode materials. Finally, this review presents a perspective toward fu-ture development and optimization for Ni-rich cathode materials, aiming at delivering a theoretical guid-ance for propelling its industrial safe application in high-energy LIBs.