Advances in synthesis and optimization of single-crystal Ni-rich cathode materials for lithium-ion batteries

Lithium-ion batteries, owing to their superior discharge capacity and relatively reasonable cycle life characteristics, have become the predominant energy storage solution in the field of electric vehicles. Single-crystal nickel-rich cathode materials (SC-NCM) are driving the development of lithium-ion battery technology due to their superior cycle stability and energy density. This review systematically examines the recent research progress of SC-NCM for lithium-ion batteries. We particularly emphasize the enhanced structural integrity, superior electrochemical performance, and reduced side reactions of single-crystal cathode materials (SC) compared to polycrystalline cathode material (PC). Subsequently, we studied various synthesis methods, including coprecipitation, hydrothermal, sol-gel, and other precursor synthesis methods, as well as high-temperature solid-state reactions and the molten salt method. We further discussed the effects of these synthesis methods on the grain morphology and electrochemical properties. Besides, we present the latest advances in optimization strategies and structural design to improve electrochemical performance. At last, we discuss the challenges of diffusion dynamics and cycle stability of lithium-ion batteries under high temperature and high voltage conditions, providing a strategic overview and target guidance for developing high energy density and long lifespan lithium-ion batteries.