Tailoring the Properties of 2D Nanomaterial-Polymer Composites for Electromagnetic Interference Shielding and Energy Storage by 3D Printing—A Review

3D-printed 2D nanomaterials-based polymer composites, with their exceptional electrical conductivity and structural functionalities, have become leading-edge engineering materials for electromagnetic interference (EMI) shielding, sensors, and energy storage applications. This review begins with a brief introduction to various types of 2D nanomaterials and their fabrication techniques, specifically different types of 3D printing. The subsequent sections highlight key factors such as rheological properties, surface tension, additives, and binders that influence the printability of 2D nanomaterials-based polymer composites. The advancements in 2D nanomaterials-based polymers, including MXene, graphene, and graphene derivatives, are then presented. The interaction, dispersion, and/or network formation of 2D nanomaterials in the polymer matrix is a crucial factor in determining the electrical performance of the composites. This review also discusses surface modification strategies for 2D nanomaterials to enhance their sensing, EMI shielding, and energy storage capabilities. Finally, the impact of various 3D-printed polymer composite geometries, such as rectangular, cylinder, and circular, on shielding performance is thoroughly examined, engaging the reader in the exploration of these materials.