Pinning Effects of Heavy Elements for the Structural Stability of Ni-Based Layered Oxides

초록

Ultrahigh-Ni layered oxides enable high-energy lithium-ion batteries (LIBs) but are plagued by lattice collapse, O release, and rapid capacity fade under high temperature and voltage operation. Here, 0.25 mol % Nb and Ta are incorporated into LiNi0.92Co0.04Mn0.04O2 to elucidate the effect of mass on structural stability. Despite identical oxidation states (+5) and radii (0.64 & Aring;), their mass difference reveals distinct pinning effects. X-ray diffraction and absorption spectroscopy analyses exhibit reduced atomic displacement, reinforced Ni-O bond strength, and expanded Li slab spacing, improving electrochemical performance upon various operating conditions. Moreover, thermal analysis confirms suppressed O release from the lattice structure and a delayed decomposition reaction, with more pronounced stabilization from heavier elements. These findings underscore an atomic-mass-driven materials design strategy as an effective approach for enhancing the durability of ultrahigh-Ni layered cathodes in next-generation LIBs.

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