Electrochemical redox processes involved in carbon-coated KVPO4F for high voltage K-ion batteries revealed by XPS analysis

Laure Caracciolo (1) , Lénaïc Madec (1, 2) , Emmanuel Petit (3, 2) , Vincent Gabaudan (4, 2) , Dany Carlier (3, 2, 5) , Laurence Croguennec (3, 2, 5) , Hervé Martinez (1, 2)

1 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux
2 RS2E - Réseau sur le stockage électrochimique de l'énergie
3 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
4 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
5 ALISTORE-ERI - Advanced Lithium Energy Storage Systems - ALISTORE-ERI

K-ion batteries need efficient positive electrode materials with open structural frameworks to accommodate the large ionic radius of K +. In that direction, polyanionic compounds are of great interest. Among them, KVPO4F is the most studied one. Its electrochemical redox processes still remain unclear, especially at high voltage. To tackle this issue, X-ray photoelectron spectroscopy was used to reveal the electrochemical redox processes of KxVPO4F. First, a carbon coating was performed and allowed increasing the overall electrochemical performance while mitigating electrolyte degradation at high voltage. Then, XPS analysis showed a high reversibility of the redox processes although the K + extraction (and insertion) from x=0.5 to 0 2 was hindered, possibly by structural constraints while electrolyte degradation occurred mostly above 4.5 V.

Domaines: Chimie; Matériaux

Laure Caracciolo, Lénaïc Madec, Emmanuel Petit, Vincent Gabaudan, Dany Carlier, et al.. Electrochemical redox processes involved in carbon-coated KVPO4F for high voltage K-ion batteries revealed by XPS analysis. Journal of The Electrochemical Society, 2020, 167 (13), 130527 (4 p.). ⟨10.1149/1945-7111/abbb0c⟩. ⟨hal-02982857⟩