Abstract: All-solid-state batteries potentially exhibit high specific energy and high safety, which is one of the development directions for next-generation lithium-ion batteries. The compatibility of all-solid composite electrodes with high-nickel layered cathodes and inorganic solid electrolytes is one of the important problems to be solved. In addition, the interface and mechanical problems of high-nickel layered cathodes and inorganic solid electrolyte composite electrodes have not been thoroughly addressed. In this paper, the possible interface and mechanical problems in the preparation of high-nickel layered cathodes and inorganic solid electrolytes and their interface reaction during charge–discharge and cycling are reviewed. The mechanical contact problems from phenomena to internal causes are also analyzed. Uniform contact between the high-nickel cathode and solid electrolyte in space and the ionic conductivity of the solid electrolyte are the prerequisites for the good performance of a high-nickel layered cathode. The interface reaction and contact loss between the high-nickel layered cathode and solid electrolyte in the composite electrode directly affect the passage of ions and electrons into the active material. The buffer layer constructed on the high-nickel cathode surface can prevent direct contact between the active material and electrolyte and slow down their interface reaction. An appropriate protective layer can also slow down the interface contact loss by reducing the volume change of the high-nickel layered cathode during charge and discharge. Finally, the following recommendations are put forward to realize the development vision of high-nickel layered cathodes: (1) develop electrochemical systems for high-nickel layered cathodes and inorganic solid electrolytes; (2) elucidate the basic science of interface and electrode processes between high-nickel layered cathodes and inorganic solid electrolytes, clarify the mechanisms of the interfacial chemical and electrochemical reactions between the two materials, and address the intrinsic safety issues; (3) strengthen the development of research and engineering technologies and their preparation methods for composite electrodes with high-nickel layered cathodes and solid electrolytes and promote the industrialization of all-solid-state batteries.