Tuning the Surface Chemistry of MXene to Improve Energy Storage: Example of Nitrification by Salt Melt

Liyuan Liu (1, 2) , Hannes Zschiesche (3) , Markus Antonietti (3) , Barbara Daffos (1, 2) , Nadezda Tarakina (3) , Mathieu Gibilaro (4) , Pierre Chamelot (4) , Laurent Massot (4) , Benjamin Duployer (1, 2) , Pierre‐louis Taberna (1, 2) , Patrice Simon (1, 2)

1 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux
2 RS2E - Réseau sur le stockage électrochimique de l'énergie
3 Max Planck Institute of Colloids and Interfaces
4 LGC - Laboratoire de Génie Chimique

The unique properties of 2D MXenes, such as metal-like electrical conductivity and versatile surface chemistry, make them appealing for various applications, including energy storage. While surface terminations of 2D MXene are expected to have a key influence on their electrochemical properties, the conventional HF-etching method limits the surface functional groups to -F, -OH, and -O. In this study, O-free, Cl-terminated MXenes (noted as Ti3C2Clx) are first synthesized by a molten salt (FeCl2) etching route. Then, a substitution of surface termination from Cl- to N- is performed via post-thermal treatment of Ti3C2Clx in Li3N containing molten salt electrolytes. While the Cl-terminated pristine material does not show electrochemical activity, the surface-modified, N-containing Ti3C2Tx exhibits a unique capacitive-like electrochemical signature in sulfuric acid aqueous electrolyte with rate performance—more than 300 F g−1 (84 mAh g−1) at 2 V s−1. These results show that control of the MXene surface chemistry enables the preparation of high-performance electrodes in a previously not accessed limit of energy storage.

Mots clés: surface termination; Ti3C2Tx MXene; molten salts approach; pseudocapacitance; supercapacitors

Domaines: Matériaux; Sciences de l'ingénieur [physics]

Liyuan Liu, Hannes Zschiesche, Markus Antonietti, Barbara Daffos, Nadezda Tarakina, et al.. Tuning the Surface Chemistry of MXene to Improve Energy Storage: Example of Nitrification by Salt Melt. Advanced Energy Materials, 2023, pp.2202709. ⟨10.1002/AENM.202202709⟩. ⟨hal-03937062⟩