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Hard carbon has attracted great attention for energy storage owing to low cost and extremely high microporosity, however, hindered by its low electrical conductivity. The common strategy to improve the conductivity is through graphitization process which requires temperatures as high as 3000 °C and inevitably destroys the porous structure. Herein, a balance between the specific surface area and electrical conductivity in a 3D porous hard carbon by in situ iron‐catalyzed graphitization process together with the Si–O–Si network is successfully achieved. The Fe can accelerate the localized graphitization at relatively low temperature (1000 °C) to form nanographite domains with enhanced conductivity, while the Si–O–Si network contributes to generating a 3D porous structure. As a result, the optimized hard carbon exhibits a 3D interconnected and hierarchical porous structure with extremely high specific surface area (2075 m2 g−1) and excellent electrical conductivity (12 S cm−1) which is comparable with that of artificial graphite. And thus, high capacitance of 315 F g−1 and excellent rate capability (174 F g−1 at 40 A g−1) are simultaneously achieved when used as electrodes for supercapacitors. The strategy is promising to build hard carbon materials with well‐tuned properties for high‐performance energy storage. [ABSTRACT FROM AUTHOR]

Highly conductive and nitrogen‐rich carbon materials have broad application prospects in energy storage, yet they are somehow contradictory because good conductivity requires high‐temperature heat treatment, which decomposes most nitrogen species. Herein, a novel approach to synthesize a nitrogen‐rich and highly conductive carbon material with extraordinary capacitance through a two‐step nitrogen‐fixation sol–gel method is reported. The process benefits from the coordination of Zn2+ with nitrogen atoms in the precursor sol and the stabilizing bonding between silicon and nitrogen during high‐temperature chemical vapor deposition. The final product shows a high nitrogen content of 5.6 at%, a hierarchical porous structure with a high specific surface area (1610 m2 g−1), and an extraordinary conductivity (23 S cm−1), which enables an impressive capacitance of 380 F g−1. This nitrogen‐fixing method starting with a composite sol–gel may offer a reliable route to the preparation of high‐performance supercapacitor electrode materials. [ABSTRACT FROM AUTHOR]

Nitrogen-doped hierarchical porous hard carbon (NPC) that are capable of high N content, high specific surface area and high chemical stability has the potential to be a promising electrode material for energy storage application. Here we report a N-doped hierarchical porous hard carbon via a facile Ti-peroxy initiated in-situ polymerization of p -phenylenediamine. Ti-peroxy can also serve as a hard template to manipulate the formation of hierarchical porous. This nitrogen-doped hierarchical porous hard carbon has advantages of high N-content (7.2 at. %) and high surface area (1515 m2 g−1), displaying a specific capacitance of 360 F g−1 and an extraordinary cycling stability above 98% after 30,000 cycles. The superoxide radical anion (O 2 ·− ) in Ti-peroxel initiated the in-situ polymerization of p -phenylenediamine and form PpPD/TiO 2 composite. Nitrogen-doped hierarchical porous hard carbon was obtained after pyrolysis and acid etching. Image 1 • Ti-peroxy with superoxide radicals initiates the in-situ polymerization of p -phenylenediamine. • Ti-peroxy as template constructs a hierarchical porous structure and provides a high surface area of 1515 m2 g−1 • The oxygen in Ti-peroxy leads to sp3 bonding. • Hierarchical porous hard carbon has a high nitrogen content (7.2 at. %) and high specific capacitance (360 F g−1). • Excellent cycling stability (>98% capacitance retention after 30,000 cycles). [ABSTRACT FROM AUTHOR]