Iron molybdate thin films prepared by sputtering and their electrochemical behavior in Li batteries

Stéphane Cotte (1) , Vincent Pelé (1) , Brigitte Pecquenard (1) , Frédéric Le Cras (2) , Rabeb Grissa (3) , Lydie Bourgeois (4) , Moulay Tahar Sougrati (5) , Hervé Martinez (3)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
2 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information
3 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux
4 ISM - Institut des Sciences Moléculaires
5 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier

With the aim of developing 3V all-solid-state lithium microbatteries, Fe$_2$(MoO$_4)_3$ thin films were prepared by radiofrequency magnetron sputtering from a home-madeFe$_2$(MoO$_4)_3$ target using optimized sputtering conditions. In addition to elemental analyses, Mössbauer spectroscopy and XPS analyses, showing that Mo$^{6+}$ and Fe$^{3+}$ are the main detected species, confirmed the stoichiometric character of the films. Post-deposition annealing was necessary to form well-crystallized thin films. The best electrochemical performance was obtained with those annealed at 500 °C which were able to deliver a stable reversible capacity close to the theoretical one, i.e. 2 Li$^+$ per Fe$_2$(MoO$_4)_3$ formula unit. The corresponding voltage curve displays a plateau with a low hysteresis located at 3.0 V/Li$^+$/Li and related to the Fe$_2$(MoO$_4)_3$ – Li$_2$Fe$_2$(MoO$_4)_3$ two-phase system. Therefore, it was demonstrated for the first time the possible use of Fe2(MoO4)3 thin films as positive electrodes for 3 V lithium microbatteries.

Mots clés: Lithium; Sputtering; Iron molybdate

Domaines: Matériaux

Stéphane Cotte, Vincent Pelé, Brigitte Pecquenard, Frédéric Le Cras, Rabeb Grissa, et al.. Iron molybdate thin films prepared by sputtering and their electrochemical behavior in Li batteries. Journal of Alloys and Compounds, 2018, 735, pp.1454-1462. ⟨10.1016/j.jallcom.2017.11.231⟩. ⟨hal-01671425⟩