A state of art critical review on advancement in MXenes for electrochemical energy storage in the view of interlayer spacing

MXenes, the fascinating 2-D material derived from transition metal carbide and nitride have received significant attention in electrochemical energy storage owing to its superior conductivity, hydrophilicity, larger specific surface area and structural topology. Numerous theoretical and experimental studies have extensively discussed its huge potential for electrochemical energy storage. In this view, we summarized the latest advancement in preparation and storage capacity of MXenes with major focus on the interlayer spacing. We begin by studying the structure topology and the preparation methods of MXenes, where different etchants such as HCl, LiF and HF were used to etch 'A' element from the MAX phases. The review then extensively discusses the adjustable interlayer spacing through pre-pillaring and final pillared technology. Finally, the conclusion and viewpoint is presented with the further applications areas of MXenes.