Influence of electrolyte on the electrode/electrolyte interface formation on InSb electrode in Mg-Ion batteries

Irshad Mohammad (1) , Lucie Blondeau (1) , Jocelyne Leroy (2) , Hicham Khodja (1) , Magali Gauthier (1)

1 LEEL - UMR 3685 - Laboratoire d'Etudes des Eléments Légers
2 LICSEN UMR 3685 - Laboratoire Innovation en Chimie des Surfaces et NanoSciences

Achieving the full potential of magnesium-ion batteries (MIBs) is still a challenge due to the lack of adequate electrodes or electrolytes. Grignard-based electrolytes show excellent Mg plating/stripping, but their incompatibility with oxide cathodes restricts their use. Conventional electrolytes like bis(trifluoromethanesulfonyl)imide ((Mg(TFSI)$_2$) solutions are incompatible with Mg metal, which hinders their application in high-energy Mg batteries. In this regard, alloys can be game changers. The insertion/extraction of Mg$^{2+}$ in alloys is possible in conventional electrolytes, suggesting the absence of a passivation layer or the formation of a conductive surface layer. Yet, the role and influence of this layer on the alloys performance have been studied only scarcely. To evaluate the reactivity of alloys, we studied InSb as a model material. Ex situ X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy were used to investigate the surface behavior of InSb in both Grignard and conventional Mg(TFSI)$_2$/DME electrolytes. For the Grignard electrolyte, we discovered an intrinsic instability of both solvent and salt against InSb. XPS showed the formation of a thick surface layer consisting of hydrocarbon species and degradation products from the solvent (THF) and salt (C$_2$H$_5$MgCl−(C$_2$H$_5$)$_2$AlCl). On the contrary, this study highlighted the stability of InSb in Mg(TFSI)$_2$ electrolyte.

Mots clés: Magnesium-ion batteries; surface chemistry; alloys; electrode surface film; electrolytes

Domaines: Matériaux

Irshad Mohammad, Lucie Blondeau, Jocelyne Leroy, Hicham Khodja, Magali Gauthier. Influence of electrolyte on the electrode/electrolyte interface formation on InSb electrode in Mg-Ion batteries. Molecules, 2021, 26 (18), pp.5721. ⟨10.3390/molecules26185721⟩. ⟨cea-03356126⟩