Ultra-high-rate pseudocapacitive energy storage in two-dimensional transition metal carbides

(Nature Energy, 2017,DOI:10.1038/nenergy.2017.105)

Two-Dimensional Transition Metal carbides (MXenes) can provide higher volume and area capacitance than carbon, conductive polymers or Transition Metal oxides at sweeping speeds beyond those of conventional double-layer capacitors. The researchers confirmed that different electrode design strategies affect the capacitance of Mxene close to the theoretical voltage window, and also showed that the extended voltage window can be obtained not only in glassy carbon, but also in other fluid collector applications. The macroporous electrode structure can retain excellent capacitance values when the charging and discharging rate is as high as 1V/s, which exceeds the reported values of carbon supercapacitors. The hydrogel electrode showed a volume capacitance of up to 1500F/cm3 and an area capacitance of 4F/cm2. This study shows that pseudorapacitors can maintain excellent performance at sweeping speeds over 10V/s, and can be used as energy harvesting and storage devices. Moreover, it is possible to realize the optimization of composite materials and structures, and to obtain more new opportunities in the field of electrochemical energy harvesting, conversion and storage.