WERNERT, Romain; NGUYEN, Long; PETIT, Emmanuel; SANZ CAMACHO, Paula; IADECOLA, Antonella; LONGO, Alessandro; FAUTH, François; STIEVANO, Lorenzo; MONCONDUIT, Laure; CARLIER, Dany; CROGUENNEC, Laurence

doi:10.1021/acs.chemmater.2c00295

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WERNERT, Romain
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
Réseau sur le stockage électrochimique de l'énergie [RS2E]

NGUYEN, Long
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
Réseau sur le stockage électrochimique de l'énergie [RS2E]

PETIT, Emmanuel
Institut de Chimie de la Matière Condensée de Bordeaux [ICMCB]
Réseau sur le stockage électrochimique de l'énergie [RS2E]

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Ce document a été publié dans

Chemistry of Materials. 2022, vol. 34, n° 10, p. 4523-4535

American Chemical Society

Résumé en anglais

Exploring and tailoring new high energy density positive electrode materials is still a challenge for alkali-ion batteries. In this work, we synthesized the mixed anion phases KVPO4F1-yOy (y = 0, 0.25, 0.5, 0.75, 1) and determined their crystallographic and electronic structures by combining synchrotron X-ray diffraction, X-ray absorption spectroscopy at the vanadium K edge, and 31P MAS NMR coupled with density functional theory calculations. These experiments confirmed that the substitution of F- for O2- anions occurs as a solid solution across the whole composition domain. The local environments of vanadium ions are complex and diverse since the cis and trans octahedra undergo different distortions in the presence of a vanadyl bond. The simultaneous existence of ionic VIII-F bonds and covalent (VIV=O)2+ vanadyl type entities is strongly affecting the electrochemical properties and potassium deinsertion/insertion mechanisms upon cycling. Ultimately, KVPO4F0.5O0.5 appears as a promising positive electrode material due to its high capacity (105 mAh·g-1), working potential (4.2 V vs K+/K), and sloping electrochemical curve.< Réduire

DOI

http://dx.doi.org/10.1021/acs.chemmater.2c00295

Project ANR

Vers des batteries innovantes K-ion - ANR-19-CE05-0026
Laboratory of excellency for electrochemical energy storage
Spectromètre EXAFS Rapide pour Cinétiques Chimiques

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Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB) - UMR 5026