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Dopant‐Dependent Stability of Garnet Solid Electrolyte Interfaces with Lithium Metal
Author(s) -
Zhu Yisi,
Connell Justin G.,
Tepavcevic Sanja,
Zapol Peter,
GarciaMendez Regina,
Taylor Nathan J.,
Sakamoto Jeff,
Ingram Brian J.,
Curtiss Larry A.,
Freeland John W.,
Fong Dillon D.,
Markovic Nenad M.
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201803440
Subject(s) - materials science , dopant , electrolyte , lithium (medication) , density functional theory , dielectric spectroscopy , chemical engineering , doping , reactivity (psychology) , electrochemistry , phase (matter) , fast ion conductor , electrode , analytical chemistry (journal) , inorganic chemistry , chemistry , computational chemistry , optoelectronics , organic chemistry , medicine , alternative medicine , pathology , engineering , endocrinology
Li 7 La 3 Zr 2 O 12 (LLZO) garnet‐based materials doped with Al, Nb, or Ta to stabilize the Li + ‐conductive cubic phase are a particularly promising class of solid electrolytes for all‐solid‐state lithium metal batteries. Understanding of the intrinsic reactivity between solid electrolytes and relevant electrode materials is crucial to developing high voltage solid‐state batteries with long lifetimes. Using a novel, surface science‐based approach to characterize the intrinsic reactivity of the Li–solid electrolyte interface, it is determined that, surprisingly, some degree of Zr reduction takes place for all three dopant types, with the extent of reduction increasing as Ta < Nb < Al. Significant reduction of Nb also takes place for Nb‐doped LLZO, with electrochemical impedance spectroscopy (EIS) of Li||Nb–LLZO||Li symmetric cells further revealing significant increases in impedance with time and suggesting that the Nb reduction propagates into the bulk. Density functional theory (DFT) calculations reveal that Nb‐doped material shows a strong preference for Nb dopants toward the interface between LLZO and Li, while Ta does not exhibit a similar preference. EIS and DFT results, coupled with the observed reduction of Zr at the interface, are consistent with the formation of an “oxygen‐deficient interphase” (ODI) layer whose structure determines the stability of the LLZO–Li interface.