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Vanadyl Phosphates A x VOPO 4 (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries
Author(s) -
Chernova Natasha A.,
Hidalgo Marc Francis V.,
Kaplan Carol,
Lee Krystal,
Buyuker Isiksu,
Siu Carrie,
Wen Bohua,
Ding Jia,
Zuba Mateusz,
Wiaderek Kamila M.,
Seymour Ieuan D.,
Britto Sylvia,
Piper Louis F. J.,
Ong Shyue Ping,
Chapman Karena W.,
Grey Clare P.,
Whittingham M. Stanley
Publication year - 2020
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.202002638
Subject(s) - materials science , alkali metal , ion , electrolyte , inorganic chemistry , cathode , redox , diffusion , metastability , chemistry , electrode , thermodynamics , physics , organic chemistry , metallurgy
Vanadyl phosphates comprise a class of multielectron cathode materials capable of cycling two Li + , about 1.66 Na + , and some K + ions per redox center. In this review, structures, thermodynamic stabilities, and ion diffusion kinetics of various A x VOPO 4 (A = Li, Na, K, NH 4 ) polymorphs are discussed. Both the experimental data and first‐principle calculations indicate kinetic limitations for alkali metal ions cycling, especially between for 0 ≤ x ≤ 1, and metastability of phases with x > 1. This creates challenges for multiple‐ion cycling, as the slow kinetics call for nanosized particles, which being metastable and reactive with organic electrolytes are prone to side reactions. Thus, various synthesis approaches, surface coating, and transition metal ion substitution strategies are discussed here as possible ways to stabilize A x VOPO 4 structures and improve alkali metal ion diffusion. The role of advanced characterization techniques, such as X‐ray absorption spectroscopy, diffraction, pair distribution function analysis and 7 Li and 31 P NMR, in understanding the reaction mechanism from both structural and electronic points of view is emphasized.