Impact of Lithium Sources on Growth Process and Structural Stability of Single‐Crystalline Li‐rich Layered Cathodes

Abstract Single‐crystalline (SC) Li‐rich layered oxides have garnered significant attention due to their inhibited lattice oxygen release and reduced crack formation compared with polycrystalline (PC) counterparts. However, it raises a crucial question regarding the selection of prevailing lithium sources‐Li 2 CO 3 and LiOH⋅H 2 O‐for the solid‐state synthesis of SC cathodes, which critically impacts the technical route and future development of SC materials. Herein, a series of SC Li‐rich layered cathodes were synthesized using these two lithium sources. The SC materials prepared with LiOH⋅H 2 O (LRO‐H) exhibited larger grain sizes compared with those using Li 2 CO 3 (LRO‐C). This can be attributed to the lower phase transition temperature of the precursor to spinel phase, which promotes further SC growth during solid‐state reactions. Furthermore, LRO‐H demonstrated excellent electrochemical stability, whereas LRO‐C exhibited superior initial capacities. To balance these attributes, a mixed lithium sources system (LRO‐M) was proposed, showing superior Li + diffusion kinetics and suppressed layered‐to‐spinel transformation, resulting in excellent rate performance and an extended battery lifespan. Altogether, these findings provide critical insights into the impact of lithium sources on the growth process, structural stability, and electrochemical properties of SC Li‐rich layered cathodes, guiding the synthesis and design of next‐generation cathode materials.