Recent advance in two-dimensional MXenes: New horizons in flexible batteries and supercapacitors technologies

MXenes (two dimensional (2D) transition metal (TM) carbides (TMCs), TM nitrides (TMNs), and TM carbonitrides (TMCNs) are emerged as future biggest 2D materials (2DMs) family with novel applications in different nanotechnological research in academic as well as industrial level. MXenes NMs have the potential to be classified as a “wonder material” in the category of 2D nanomaterials (NMs). MXenes were studied and synthesized for over a decade since their first discovery in 2011, and till now more than 50 members are experimentally studied and more than 100 are theoretically investigated. Synthesis techniques are not restricted to the first introduced top-down HF based etching method but new innovative synthesis methods, such as, water (H₂O)-free etching, molten salts etching and bottom-up method, like Chemical vapor deposition (CVD) method etc were also studied, providing multifunctional surface chemistry based MXenes NMs with novel configuration, and desirable characteristics. MXenes are used as important components in a number of flexible energy storage devices (FESDs), for instance secondary batteries, supercapacitors (SCs), Micro-SCs (MSCs) and Micro-batteries (MBs), etc due to their distinctive layered structures, high electrochemical performance and fascinating functional capabilities. In this review, we first will discuss in detail the MXenes NMs synthesis methods, secondly selected properties, and third their applications in various FESDs. After that, we will summarize and discuss the most present problems associated with MXenes NMs synthesis and their applications in FESDs, and possible solutions to those problems. Finally we will discuss the presents interesting vision for the future progress of the MXenes-based NMs in wearable and FESDs, their limitations, and suggestions.