Three-dimensional printing of graphene-based materials for energy storage and conversion

Developing high-performance energy storage and conversion (ESC) device relies on both the utilization of good constituent materials and rational design of assembly structure. Graphene-based materials, due to their superior properties like high electrical/thermal conductivity, large surface area, and unique optical properties, have been extensively reported for ESC applications. The emerging three-dimensional (3D) printing techniques, especially extrusion-based direct ink writing technique, have brought a revolutionary improvement in structure control accuracy and designing capability to graphene-based macro-assemblies, triggering a boost in functionalities and performances of graphene-based ESC devices. In these circumstances, understanding the very recent progress of 3D-printed graphene materials and their design philosophy to bring new concepts for material designs and address the requirements for high-performance ESC devices are urgently important. In this review, we aim to outline recent developments in 3D printing of graphene-based materials and their applications in ESC applications. Basic requirements and theoretical analysis for preparation printable inks are discussed, as well as feasible GO ink preparation strategies in existing literatures. The representative explorations of 3D-printed graphene materials in ESC applications like batteries, supercapacitors, solar steam generators, and electro-thermal conversion are also reviewed. This study attempts to provide a comprehensive overview of the progresses and limitations of present 3D printed graphene materials, and seeks to enlighten the opportunities and orientations of future research in this field.