Abstract
This work explores the core/shell structure (Ni-rich core, Mn-rich shell) as a promising approach to improve interfacial stability in high-nickel cathode materials. This structure reduces surface reactivity without sacrificing capacity. Traditionally, co-precipitation is used to synthesize these materials. Here, we investigate the impact of manganese (Mn) oxidation state during drying on the physicochemical and electrochemical properties. We focus on how this state depends on the sintering temperature. Our findings reveal that the presence of oxidized Mn in the precursor lattice can mitigate further transition metal (TM) oxidation at lower sintering temperatures. This also induces oxygen vacancies on the particle surface. However, this leads to poor electrochemical performance due to two factors: the magnetic frustration effect and the “cross-talk effect” caused by TM dissolution and deposition on the graphite anode. In contrast, higher sintering temperatures promote complete Mn oxidation in the precursors. This kinetically suppresses Mn diffusion, preserving the core/shell structure and minimizing surface defects. This approach also demonstrably suppresses the cross-talk effect.This study highlights the profound influence of surface Mn oxidation state in core/shell high-nickel cathode material precursors. The oxidation state impacts surface properties, intrinsic characteristics, and reaction kinetics during heat treatment. Consequently, this research emphasizes the critical role of precursor surface chemistry and offers valuable insights for developing strategies to enhance cathode material interface stability.Keywords: Ni-rich cathode / Core-Shell structure / Precursor surface oxidation / Transition metal dissolution / Magnetic Frustration
Published Version
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