Tailoring ion-accessible pores of robust nitrogen heteroatomic carbon nanoparticles for high-capacity and long-life Zn-ion storage

Designing highly endogenous zincophilic sites and ion-accessible pore architectures is crucial but remains a formidable challenge for carbon cathodes in zinc-ion hybrid capacitors (ZHCs) with superior capacity activity and ultralong cycling life. Herein, nitrogen heteroatomic carbon nanoparticles with hierarchical porous architectures were tailor-made by a well-established and efficient Schiff base reaction. The nucleophilic addition of amine modules and reactive carbonyl groups forms ordered organic nanoparticles with the specific internal ring pore size (1.27 nm) and high-level N heteroatomic doping. The tailored internal ring pore size, the robust macroporous networks formed by aggregated and interwoven nanoparticles and controlled carbonization/activation processes collaborate to obtain hierarchical porous architectures, robust carbon skeletons and high specific surface area (SSA) (2504 m² g⁻¹). Most notably, the pore architectures of NHPCs-700 (∼1.2 nm) can perfectly match the solvated ion diameter of Zn²⁺ (0.86 nm) and CF₃SO₃⁻ (1.16 nm), realizing highly accessibility of zincophilic sites and fast diffusion behaviors. Additionally, ex-situ characterization and DFT calculation reveal the following energy storage mechanism: the ultrahigh zinc-ion capturing ability of pyridine N motifs, and fast diffusion behaviors alternately physical uptake of Zn²⁺/CF₃SO₃⁻ charge carriers. The highly endogenous zincophilic sites, ion-accessible pore architectures and dual ion storage mechanism ensure exceptional specific capacity (253 mAh g⁻¹ at 0.2 A g⁻¹), outstanding energy density (157.8 Wh kg⁻¹ at 125.3 W kg⁻¹), and ultralong cycling life (200, 000 cycles at 10 A g⁻¹). This work provides a strategic fabrication method for the advanced carbon cathodes with highly endogenous zincophilic site.