Three-Dimensional Printed MXene@PANI Hierarchical Architecture for High-Performance Micro-Supercapacitors.

The advent of the Internet of Things has boosted portable and wearable miniature electronics, especially micro-supercapacitors (MSCs) with excellent integrated performance as well as high-power density and a long lifetime. However, the rational design of electrode material formulations and the construction of three-dimensional (3D) structured electrodes with scalable and cost-effective fabrication remains an arduous task for improving the energy density of MSCs to meet all industrial sector requirements, such as the mass-production of microscale structures, a lasting power supply, and safety. To address these challenges, combining the respective capacitance merits of MXenes and polyaniline (PANI), we propose a constructing strategy for the preparation of a 3D MXene@PANI hierarchical architecture consisting of one-dimensional (1D) PANI nanofibers grown on two-dimensional (2D) TiC MXene nanosheets via extrusion-based 3D printing. Such a 3D architecture not only achieves a high loading mass of MSC electrodes prior to conventional planar MSCs for abundant active site exposure, but it also overcomes the restacking of MXene nanosheets accounting for sluggish ionic kinetics. These features enable the resulting MSCs to deliver excellent electrochemical properties, including a high volumetric capacitance of 1638.3 mF/cm and volumetric energy density of 328.2 mWh/cm. This power supply ability is further demonstrated by lighting up a blue bulb or powering an electronic thermometer. This study provides a promising design strategy of the architecture of MXene@PANI composites for high-performance MSCs with 3D printing technology.