Poly(ionic liquid)-Stabilized Graphene Nanoinks for Scalable 3D Printing of Graphene Aerogels

Stable dispersions of pristine graphene in innocuous mediums are highly desired for the use of this 2D material into a variety of practical applications. Here, we report the direct layerby-layer fabrication of high-quality graphene nanosheets in aqueous dispersions into three-dimensional graphene aerogels with hierarchical structure by freeze 3D printing. Water-soluble imidazolium-based poly(ionic liquid)s, which offer the synergy of high conductivity and pi-stacking interactions with graphitic carbon, were prepared and utilized as stabilizers for graphite exfoliation in an aqueous medium. Stable and highly concentrated graphene dispersions in water with concentrations as high as 5 mg mL(-1) were obtained, which showed excellent ejectability through a wide range of nozzles. A freeze 3D printing technique was developed by integrating a precision dispensing system with a rapid cryogenization process using a Peltier module, advancing the capability to print the formulated graphene nanoinks into three-dimensional macroscopic structures. This technique provides a scalable and versatile process for layer-by-layer fabrication of 3D graphene aerogels, which may find importance in a myriad of applications, especially for batteries and supercapacitors.