Predicting Degradation Mechanisms in Lithium Bistriflimide “Water‐In‐Salt” Electrolytes For Aqueous Batteries

Malaurie Paillot (1) , Alan Wong (1) , Sergey A. Denisov (2) , Patrick Soudan (3) , Philippe Poizot (3) , Bénédicte Claude-Montigny (4) , Mehran Mostafavi (2) , Magali Gauthier (1) , Sophie Le Caër (1, 5)

1 NIMBE UMR 3685 - Nanosciences et Innovation pour les Matériaux, la Biomédecine et l'Energie (ex SIS2M)
2 ICP - Institut de Chimie Physique
3 IMN - Institut des Matériaux de Nantes Jean Rouxel
4 PCM2E - Physico-chimie des Matériaux et des Electrolytes pour l'Energie
5 LIONS - Laboratoire Interdisciplinaire sur l'Organisation Nanométrique et Supramoléculaire

Aqueous solutions are crucial to most domains in biology and chemistry, including in energy fields such as catalysis and batteries. Water‐in‐salt electrolytes (WISEs), which extend the stability of aqueous electrolytes in rechargeable batteries, are one example. While the hype for WISEs is huge, commercial WISE‐based rechargeable batteries are still far from reality, and there remain several fundamental knowledge gaps such as those related to their long‐term reactivity and stability. Here, we propose a comprehensive approach to accelerating the study of WISE reactivity by using radiolysis to exacerbate the degradation mechanisms of concentrated LiTFSI‐based aqueous solutions. We find that the nature of the degradation species depends strongly on the molality of the electrolye, with degradation routes driven by the water or the anion at low or high molalities, respectively. The main aging products are consistent with those observed by electrochemical cycling, yet radiolysis also reveals minor degradation species, providing a unique glimpse of the long‐term (un)stability of these electrolytes.

Domains: Chemical Sciences

Malaurie Paillot, Alan Wong, Sergey A. Denisov, Patrick Soudan, Philippe Poizot, et al.. Predicting Degradation Mechanisms in Lithium Bistriflimide “Water‐In‐Salt” Electrolytes For Aqueous Batteries. ChemSusChem, 2023, 16 (23), pp.e202300692. ⟨10.1002/cssc.202300692⟩. ⟨hal-04252558⟩