Facile separation of lithium fluoride to boost the electrical conductivity of MXene sediment

Printing technologies have enabled the low-cost and large-scale production of MXene-based transparent conductive electrodes. Fabrication of inks with MXene monolayers in liquid phase for printing requires bespoke centrifugation separation, and the yield is low. MXene sediment, a byproduct of the centrifugation separation process, is a rich source for creating concentrated MXene inks. However, removing impurities, particularly lithium fluoride, from sediment remains a significant challenge for producing high-quality inks. This study reported the first purification route for removing lithium fluoride from sediment by controlling the addition of lithium fluoride during the etching of MAX precursors. This approach resulted in formation of a concentrated ink consisting of large-sized MXene monolayers. The vacuum-filtered film exhibited ultra-high conductivity exceeding 20,000 S cm⁻¹. Furthermore, gravure printing produced a TCE with a low sheet resistance of 560 Ω sq⁻¹ and 84% transmittance without the need of annealing post-treatment.