Three-dimensional printing of complex graphite structures

Abstract

Graphite, with many industrial applications, is one of the widely sought-after allotropes of carbon. Although the geometric design of the graphite in many of the applications could dictate its precision performance, conventional synthesis methods for formulating complex geometric graphite shapes are limited due to the intrinsic brittleness and difficulties of high-temperature processing. Here, we report the development of colloidal ink from commercial graphite powders that allows the fabrication of any complex architectures with tunable geometry and directionality via 3D printing at room temperature. The method is enabled via using very small amounts of clay as an additive, allowing the proper design of the graphite-based ink and subsequent binding of graphite platelets during printing. Sheared layers of clay are easily able to flow, adapt, and interface with graphite layers forming strong binding between the layers that make the larger structures. The direct ink writing of complex graphitic architectures without further heat treatments could lead to easy shape engineering and related applications of graphite at various length scales. The printed structures exhibit excellent thermal, electrical, and mechanical properties, and the clay additive does not seem to alter these properties due to the excellent inter-layer dispersion and mixing within the graphite material.