Dual cation- and anion-based redox process in lithium titanium oxysulfide thin film cathodes

Vincent Dubois (1, 2) , Brigitte Pecquenard (2) , Samantha Soulé (3) , Hervé Martinez (3) , Frédéric Le Cras (4, 5)

1 STMicroelectronics
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
3 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux
4 CEA - Commissariat à l'énergie atomique et aux énergies alternatives
5 LITEN - Laboratoire d'Innovation pour les Technologies des Energies Nouvelles et les nanomatériaux

A dual redox process involving Ti3+/Ti4+ cation species and S2–/(S2)2– anion species is highlighted in oxygenated lithium titanium sulfide thin film electrodes during lithium (de)insertion, leading to a high specific capacity. These cathodes for all-solid-state lithium-ion microbatteries are synthesized by sputtering of LiTiS2 targets prepared by different means. The limited oxygenation of the films that is induced during the sputtering process favors the occurrence of the S2–/(S2)2– redox process at the expense of the Ti3+/Ti4+ one during the battery operation, and influences its voltage profile. Finally, a perfect reversibility of both electrochemical processes is observed, whatever the initial film composition. All-solid-state lithium microbatteries using these amorphous lithiated titanium disulfide thin films and operated between 1.5 and 3.0 V/Li+/Li deliver a greater capacity (210–270 mAh g–1) than LiCoO2, with a perfect capacity retention (−0.0015% cycle–1).

Mots clés: disulfide pairs; titanium sulfide; thin films; all-solid-state lithium batteries; LiTiS 2

Domaines: Matériaux

Vincent Dubois, Brigitte Pecquenard, Samantha Soulé, Hervé Martinez, Frédéric Le Cras. Dual cation- and anion-based redox process in lithium titanium oxysulfide thin film cathodes. ACS Applied Materials & Interfaces, 2017, 9 (3), pp.2275-2284. ⟨10.1021/acsami.6b11987⟩. ⟨hal-01450521⟩