Recent Progress on Synthetic Design for Cathode Materials of Lithium Ion Batteries Aided by Advanced Multi-Scale Analysis

The development of cathode materials with high energy density and low cost is becoming increasingly critical to meet the expanding demands of the lithium-ion battery market. Since the structure and electrochemical properties of cathode materials are highly sensitive to synthesis conditions, precise control and rational design of synthesis processes are essential for their practical applications. However, mechanistic understanding of synthesis reactions has been limited, largely due to the hierarchically complex architecture of secondary particle-based cathodes and the challenges associated with their characterizations. This review summarizes recent progress on uncovering the chemical and structural evolution of layered oxide cathodes across multi-length scales ranging from atomistic, nano to micrometer during solid-state calcination, by leveraging advanced analysis tools. We also highlight recent efforts on the design and optimization of the calcination processes to obtain highly stable and better performing cathode materials, guided by multiscale and in situ probing of the synthesis reactions.