3D printing of architectured graphene-based aerogels by cross-linking GO inks with adjustable viscoelasticity for energy storage devices

Three-dimensional (3D) functional graphene-based architecture with superior electrical conductivity and good mechanical strength has promising applications in energy storage and electrics. Viscoelasticity-adjustable inks make it possible to achieve desired 3D architectures with interconnected and continuous interior networks by micro-extrusion printing. In this work, ultra-low-concentration graphene oxide (GO) inks of ~ 15 mg·ml⁻¹ have been obtained and demonstrated in direct 3D printing with a facile cross-linking (direct ink writing). The rheological behavior of the GO strategy by cations, which is the lowest concentration to achieve direct ink writing inks, could be adjusted from 1×10⁴ to 1×10⁵ Pa·s⁻¹ with different concentrations of cations due to strong cross-linking networks between GO sheets and cations. Meanwhile, the specific strength and electrical conductivity of 3D-printed graphene architecture are notably enhanced, reaching up to 51.7 × 10³ N·m·kg⁻¹ and 119 S·m⁻¹, which are superior to conventional graphene aerogels. Furthermore, 3D printing graphene-based architecture assembled in micro-supercapacitor exhibits excellent electrochemical performance, which can be ascribed to the effective ion transportation through the interconnected networks. The strategy demonstrated is useful in the design of complex-shaped, graphene-based architectures for scalable manufacturing of practical energy storage applications.