Vanadyl Phosphates AxVOPO4 (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries. Issue 47 (30th October 2020)

• Record Type: Journal Article
• Authors: 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
• Is Part Of: Advanced energy materials. Volume 10:Issue 47(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-10-30
• Subjects: cathode materials -- Li‐ion batteries -- vanadium compounds; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202002638
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: 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 VOPO4 (A = Li, Na, K, NH4 ) 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 VOPO4 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. Abstract : In this review, the vanadyl phosphates A x VOPO4 (A = Li, Na, K) are discussed as cathode materials for alkali‐ion batteries. It is shown that despite poor electronic and ionic conductivities, and reactivity with the electrolyte, it is possible to create well‐crystalline nanocrystals with a stable surface capable of cycling two lithium ions at useful current densities.