Metal Ion-Induced Porous MXene for All-Solid-State Flexible Supercapacitors.

MXenes are normally used for energy storage applications. However, large nanosheets and restacking are detrimental to the ion diffusion and thus limit its rate capability. Here, a strategy to prepare flexible and porous MXene-M supercapacitor electrodes can simultaneously enlarge the interlayer spacing between layers and create holes in the layers. As a result, Ti 3 C 2 T x -Mn presents an excellent lifespan, with still 248 F g -1 after 100 000 cycles at a current density of 100 A g -1 . Moreover, Ti 3 C 2 T x -Mn-based symmetric all-solid-state supercapacitor exhibits outstanding volumetric energy up to 52.4 mWh cm -3 and retains 38.4 mWh cm -3 at an ultrahigh volumetric power density of 55.3 W cm -3 . We believe this work provides an idea for the later regulation of MXene layer spacing and the design of porous structures, and can be widely used in the next-generation high-energy density and power density practical applications.