Template-Free N-doped Hierarchical Porous Carbon from Azobenzene-Interconnected Polyimide for Ultra-Stable Supercapacitor Electrodes

Facile preparation of N-doped hierarchical porous carbon (NHPC) materials with controllable composition and porosity is crucial for advancing the development of highperformance supercapacitors. In this study, a new NHPC has been created by first using the one-pot synthesis of in-situ dual-crosslinking azobenzene-interconnected polyimide precursors from ingeniously designed three monomers, followed by carbonization activation. We have found that during the polymer precursor synthesis stage, the incorporation of azobenzene into the polyimide network is the key, as it not only functions as an in-situ N-rich source but also enables the template-free formation of a multi-scale micro/nanoporous carbon structure, which is critical for enhancing electrical performance and stability. The resulting N-doped carbon material with a specific surface area of 900.1 m2 g −1 exhibits a maximum capacitance of 179.2 F g−1 in a three-electrode configuration. The assembled symmetric supercapacitor using NHPC as the electrode delivers a good energy density (18.0 Wh kg−1 ) and power density (799.51 W kg−1 ) at a current density of 1 A g−1 . Most notably, the NHPC electrode retains an efficiency of 113.5% without decrease, demonstrating impressive cycling stability, even after 5000 chargedischarge cycles at 10 A g−1 . This study offers a new and universal molecular design methodology for advancing supercapacitor materials with outstanding cycling stabilities.

可控组成与孔隙结构的氮掺杂分级多孔碳（N-doped hierarchical porous carbon, NHPC）材料的简便制备，对于推动高性能超级电容器的发展至关重要。本研究通过巧妙设计三种单体，先采用一锅法合成原位双交联偶氮苯交联聚酰亚胺前驱体，再经炭化活化，制备得到一种新型NHPC材料。研究发现，在聚合物前驱体的合成阶段，将偶氮苯引入聚酰亚胺网络是关键所在：其不仅可作为原位富氮源，还能实现无模板多级微/纳多孔碳结构的构建，这对提升材料的电学性能与稳定性具有重要意义。所得氮掺杂碳材料的比表面积达900.1 m²·g⁻¹，在三电极体系中展现出179.2 F·g⁻¹的最大比电容。以NHPC作为电极组装的对称型超级电容器，在1 A·g⁻¹的电流密度下，可实现18.0 Wh·kg⁻¹的能量密度与799.51 W·kg⁻¹的功率密度，性能优异。尤为值得关注的是，该NHPC电极在10 A·g⁻¹下经过5000次充放电循环后，容量保持率仍达113.5%且无衰减，展现出极佳的循环稳定性。本研究为开发具备卓越循环稳定性的超级电容器材料提供了一种全新且通用的分子设计方法论。