Hierarchical Pore Engineering of Slope-Type Hard Carbon for Enhanced Sodium-Ion Storage

Designing hierarchical porous structures is widely recognized as an effective strategy to improve ion transport and create active sites for disordered carbon anodes of sodium-ion batteries (SIBs). Herein, hierarchical porous hard carbon (hp-HC) is synthesized using zinc acetate as a templating agent. The hierarchical porous structure facilitates effective Na⁺ ion storage with a high reversible capacity of 327 mA h g⁻¹ at a current density of 0.1 A g⁻¹. Notably, the sodium storage behavior is capacitance-dominated, with the capacity primarily characterized by slope capacity. Additionally, the hp-HC retains 94.5 % of its capacity after 6000 cycles at 1.0 A g⁻¹. This work provides a convenient route for manipulating pore types, which is of great significance for developing high-capacity hard carbon electrodes for enhanced sodium-ion storage.