Geometric Stress Mitigation Through Particle Morphology Optimization in Cobalt-Free Layered Oxide Cathodes

초록

Systematic electrochemical evaluation of cobalt-free layered oxide cathodes reveals unexpected morphology-dependentdegradation resistance mechanisms that transcend conventional compositional optimizationstrategies. Comparative analysis of LiNi0.5Co0.2Mn0.3O2 (NCM523) and LiNi0.7Mn0.3O2 (NMx73) compositionsunder equivalent high-voltage cycling protocols demonstrates superior mechanical stability in the cobalt-free systemdespite experiencing enhanced crystallographic strain. In situ X-ray diffraction monitoring quantifies greaterstructural perturbations in NMx73, yet cross-sectional microstructural analysis provides compelling evidence thatelongated particle morphology enables superior stress accommodation through geometric deformation mechanismsrather than catastrophic crack propagation. The mechanistic framework establishes particle geometry as acritical design parameter governing electrochemical durability, with elongated architectures providing enhancedstress distribution capabilities that compensate for increased structural evolution. These findings establish morphologicalengineering as a transformative paradigm for cathode material design, offering particular significancefor sustainable battery technologies where cobalt elimination necessitates alternative pathways to structural stabilitythrough geometric optimization rather than purely compositional modifications.

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