Ti3C2-MXene composite films functionalized with polypyrrole and ionic liquid-based microemulsion particles for supercapacitor applications

Stemming from its unique structure and properties, Ti3C2-MXenes have stood out from the crowd of electrode materials due to effectively ameliorating imperfections of common ones for excellent energy storage. However, a major stumbling block in the further development of MXene-based supercapacitors is the inherent low capacities caused by severe restacking of nanosheets. Herein, we develop a simple, effective and innovative strategy, namely, introducing both polymerized polypyrrole (PPy) particles and ionic liquid (ILs)-based microemulsion particles as dual spacers, to fabricate functionalized Ti3C2-MXene composite films for high-performance and wide-temperature application in supercapacitors. The PPy particles acting as one spacer circumvent restacking issues of MXene nanosheets, while contribute to desirable capacitance of the hybrid material. ILs-based micro-emulsions spontaneously adsorbing onto PPy-Ti3C2Tx nanosheets are conceived to be one more liquid spacer for fast ion diffusion kinetics and absent electrolyte imbibition steps, which is rarely reported in previous research for MXene-based electrode materials. These features endow the composite films with excellent specific capacitance, rate capability and cycling stability between 4 degrees C and 50 degrees C. At room temperature, the symmetric supercapacitor device based on the composite films delivers a maximum gravimetric energy density of 31.2 Wh kg(-1) (at 1030.4 W kg(-1)) and reserves 91% of the initial specific capacitance with a coulombic efficiency of 91% after 2000 cycles. All these impressive results substantiate that the composite films prepared by ingenious structure design showcase huge potentials in advanced MXene-based supercapacitors using various ionic liquid electrolytes.

Automated summary

A novel strategy utilizing polymerized polypyrrole (PPy) particles and ionic liquid (ILs)-based microemulsion particles as dual spacers is developed to fabricate functionalized Ti3C2-MXene composite films for high-performance supercapacitors. The PPy particles circumvent restacking issues of MXene nanosheets and contribute to desirable capacitance, while ILs-based microemulsions improve fast ion diffusion kinetics and electrolyte imbibition steps, resulting in excellent specific capacitance, rate capability, and cycling stability. The composite films show great potential in advanced MXene-based supercapacitors using various ionic liquid electrolytes, achieving high energy density and maintaining high coulombic efficiency after 2000 cycles.