Roadblocks in Cation Diffusion Pathways: Implications of Phase Boundaries for Li-Ion Diffusivity in an Intercalation Cathode Material.

Autor:	Luo Y; Department of Chemistry, Department of Materials Science & Engineering , Texas A&M University , College Station , Texas 77843 , United States., De Jesus LR; Department of Chemistry, Department of Materials Science & Engineering , Texas A&M University , College Station , Texas 77843 , United States., Andrews JL; Department of Chemistry, Department of Materials Science & Engineering , Texas A&M University , College Station , Texas 77843 , United States., Parija A; Department of Chemistry, Department of Materials Science & Engineering , Texas A&M University , College Station , Texas 77843 , United States., Fleer N; Department of Chemistry, Department of Materials Science & Engineering , Texas A&M University , College Station , Texas 77843 , United States., Robles DJ; School of Mechanical Engineering , Purdue University , West Lafayette , Indiana 47907 , United States., Mukherjee PP; School of Mechanical Engineering , Purdue University , West Lafayette , Indiana 47907 , United States., Banerjee S; Department of Chemistry, Department of Materials Science & Engineering , Texas A&M University , College Station , Texas 77843 , United States.
Jazyk:	angličtina
Zdroj:	ACS applied materials & interfaces [ACS Appl Mater Interfaces] 2018 Sep 12; Vol. 10 (36), pp. 30901-30911. Date of Electronic Publication: 2018 Aug 28.
DOI:	10.1021/acsami.8b10604
Abstrakt:	Increasing intercalation of Li-ions brings about distortive structural transformations in several canonical intercalation hosts. Such phase transformations require the energy dissipative creation and motion of dislocations at the interface between the parent lattice and the nucleated Li-rich phase. Phase inhomogeneities within particles and across electrodes give rise to pronounced stress gradients, which can result in capacity fading. How such transformations alter Li-ion diffusivities remains much less explored. In this article, we use layered V 2 O 5 as an intercalation host and examine the structural origins of the evolution of Li-ion diffusivities with phase progression upon electrochemical lithiation. Galvanostatic intermittent titration measurements show a greater than 4 orders of magnitude alteration of Li-ion diffusivity in V 2 O 5 as a function of the extent of lithiation. Pronounced dips in Li-ion diffusivities are correlated with the presence of phase mixtures as determined by Raman spectroscopy and X-ray diffraction, whereas monophasic regimes correspond to the highest Li-ion diffusivity values measured within this range. First-principles density functional theory calculations confirm that the variations in Li-ion diffusivity do not stem from intrinsic differences in diffusion pathways across the different lithiated V 2 O 5 phases, which despite differences in the local coordination environments of Li-ions show comparable migration barriers. Scanning transmission X-ray microscopy measurements indicate the stabilization of distinct domains reflecting the phase coexistence of multiple lithiated phases within individual actively intercalating particles. The results thus provide fundamental insight into the considerable ion transport penalties incurred as a result of phase boundaries formed within actively intercalating particles. The combination of electrochemical studies with ensemble structural characterization and single-particle X-ray imaging of phase boundaries demonstrates the profound impact of interfacial phenomena on macroscopic electrode properties.
Databáze:	MEDLINE
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