A Facile, High-Yield, and Freeze-and-Thaw-Assisted Approach to Fabricate MXene with Plentiful Wrinkles and Its Application in On-Chip Micro-Supercapacitors

MXene, as a new member of the two-dimensional (2D) material family, has been widely studied. However, people often pay close attention to the versatility of MXene while ignoring its low exfoliation yield. In this work, a simplified and effective strategy to exfoliate multilayer-MXene via the gentle water freezing-and-thawing (FAT) approach is proposed. The volume expansion of intercalated water can promote the exfoliation of MXene nanosheets. The yield of large FAT-MXene flakes with special wrinkles can reach 39% after four cycles of the FAT process. Moreover, combining with sonication treatment can boost the yield of small MXene to a record high value of 81.4%. With the help of a commercial interdigital mask, an on-chip all-MXene micro-supercapacitor (MSC) assembled by large FAT-MXene is fabricated, exhibiting high areal and volumetric capacitance of 23.6 mF cm(-2) and 591 F cm(-3), respectively. This remarkable electrochemical performance of MXene-MSC also confirms the high quality of MXene through this FAT strategy. This study may open up a new method to simultaneously boost the yield of MXene with small or large flake sizes, facilitating large-scale and size-dependent research on MXene.