Characterization by NMR Spectroscopy of the SEI Layer Formed on Ti3C2 MXene Materials Prepared with Various Terminations

Abstract The nature and content of surface terminations are one of the key factors that define the electrochemical signature of the widely studied MXene materials. Here, the surface termination of molten salt synthesized Ti3C2Tx MXene with -O and -Cl terminations (T= Cl,O) were studied for the first time using solid state nuclear magnetic resonace (NMR) technique, with respect to conventional HF synthesized Ti3C2Tx (T= F, O, OH). Both materials have been further used as negative electrode of Li-ion battery. The evolution of surface terminations during the solid electrolyte interphase (SEI) layer formation was studied from the SEI components formed in both MXenes. Analysis of the NMR signal provided insights into the porous nature of SEI with LiF as main component in HF terminated MXenes. While a thick uniform formation of the SEI was observed for the molten salt synthesized Ti3C2Tx (T= Cl,O) with Li2CO3 as dominant component.