MXenes as High-Rate Electrodes for Energy Storage

MXenes are 2D materials that offer great promise for electrochemical energy storage. While MXene electrodes achieve high specific capacitance and power rate performance in aqueous electrolytes, the narrow potential window limits the practical interest of these systems. The development of new synthesis methods to prepare MXenes, such as by using a molten salt approach, broadens the variety of precursors that can be used. In addition, these methods allow for tuning the nature and content of the surface functional groups present at the MXene surface. Recent studies reported high performance for MXene electrodes in nonaqueous electrolytes with both high capacity, high voltage, and fast charge–discharge rate. Those performances, ascribed to the control of the MXene/electrolyte interface, offer new opportunities for designing the next generation of high-rate materials for energy storage applications. Two-dimensional transition-metal carbides/nitrides, namely MXenes, are gaining increasing interest in many research fields, including electrochemical energy storage. This short review article emphasizes some recent breakthroughs achieved in MXene chemistry and electrochemical performance when used as high-rate electrodes, especially in nonaqueous electrolytes. Lastly, the current limitations and future perspectives are highlighted. Two-dimensional transition-metal carbides/nitrides, namely MXenes, are gaining increasing interest in many research fields, including electrochemical energy storage. This short review article emphasizes some recent breakthroughs achieved in MXene chemistry and electrochemical performance when used as high-rate electrodes, especially in nonaqueous electrolytes. Lastly, the current limitations and future perspectives are highlighted. a widely used electrochemical technique. The principle is to apply a linear voltage ramp to an electrode (or a device) between two voltage limits and measure the resulting current. the amount of energy stored in a given energy storage device normalized with the mass or volume. The SI unit is J/m3 or J/kg (Wh/l, Wh/kg are commonly used for batteries and supercapacitors). an electrochemical technique of applying a constant to charge/discharge the electrochemical cell or electrode within the control potential range. salts composed solely of ions with melting points below 100°C. 1.0 M lithium hexafluorophosphate (Li-PF6) in ethylene carbonate (EC) and dimethyl carbonate (DMC) organic solvents with a volume ratio of 1:1. salts composed solely of ions, but with higher melting points. capacitance is the ratio of the charge change of a system to the corresponding potential change. In supercapacitors, capacitances of the electrode (or cell) are typically normalized with the electrode (or cell) mass, volume, and areal, which are termed as specific gravimetric, areal, and volumetric capacitance, respectively.