Investigating the local structure of Ti based MXene materials by temperature dependent X-ray absorption spectroscopy

The local structures of Ti based MXene-type electrode materials have been studied by Ti K-edge X-ray absorption fine structure measurements as a function of temperature to obtain direct information on the local bond lengths and their stiffness. In particular, the parent MAX phases Ti2AlC and Ti3AlC2 and their etched MXene systems are characterized and their properties compared. We find that selective etching has a substantial effect on the local structural properties of the Ti based MXene materials. It leads to an increase in the interatomic distances, i.e. a decrease in the covalency, and corresponding bond stiffness, that is a likely cause of higher achievable performances. The obtained results underline the importance of the local atomic correlations as limiting factors in the diffusion capacity of ion batteries.

Automated summary

The local structures of Ti based MXene-type electrode materials were investigated using Ti K-edge X-ray absorption fine structure measurements. The effects of temperature on the local bond lengths and their stiffness were studied. Selective etching was found to significantly affect the local structural properties of Ti based MXene materials, resulting in increased interatomic distances and higher achievable performances. These results highlight the importance of local atomic correlations as limiting factors in the diffusion capacity of ion batteries.