Precursor Engineering for Kinetically Controlled Synthesis of Crack-Resistant LiCoO2 Cathodes

초록

Intragranular cracking within primary particles is a critical but poorly understood degradation mechanism that severely limits the long-term stability of layered cathode materials for lithium-ion batteries. Conventional synthesis methods often produce polycrystalline primary particles with internal grain boundaries that act as stress concentration sites, leading to mechanical failure. Herein, using LiCoO2 (LCO) as a model system, we introduce a novel precursor engineering strategy to suppress intragranular cracking by controlling the crystallinity of the primary particles. By transforming a conventional Co(OH)2 precursor into an anion-exchanged Co2N0.67 nitride, we successfully modulated the solid-state reaction kinetics for LCO synthesis. This nitride-mediated pathway induced a slower, more controlled reaction, promoting the growth of 'true single-crystal' primary particles devoid of internal grain boundaries. As a result, the engineered LCO exhibited enhanced long-term cycling stability and rate capability, which is attributed to the effective mitigation of mechanical stress and microcrack formation. This work establishes precursor engineering as a powerful and scalable design principle for developing mechanically robust, high-energy layered cathodes for next-generation energy storage applications.

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