Three-Phase Boundary in Cross-Coupled Micro-Mesoporous Networks Enabling 3D-Printed and Ionogel-Based...

The construction of advanced micro-supercapacitors (MSCs) with both wide working-voltage and high energy density is promising but still challenging. In this work, a series of nitrogen-doped, cross-coupled micro-mesoporous carbon-metal networks (N-STC/M_x O_y ) is developed as robust additives to 3D printing inks for MSCs fabrication. Taking the N-STC/Fe₂ O₃ nanocomposite as an example, both experimental results and theoretical simulations reveal that the well-developed hierarchical networks with abundantly decorated ultrafine Fe₂ O₃ nanoparticles not only significantly facilitate the ion adsorption at its three-phase boundaries (Fe₂ O₃ , N-STC, and electrolyte), but also greatly favor ionic diffusion/transport with shortened pathways. Consequently, the as-prepared N-STC/Fe₂ O₃ electrode delivers a high gravimetric capacitance (267 F g^-1 at 2 mV s^-1 ) and outstanding stability in a liquid-electrolyte-based symmetric device, as well as a record-high energy density of 114 Wh kg^-1 for an asymmetric supercapacitor. Particularly, the gravimetric capacitance of the ionogel-based quasi-solid-state MSCs by 3D printing reaches 377 F g^-1 and the device can operate under a wide temperature range (-10 to 60 °C).