Three-Dimensional Ordered Macroporous Metal-Organic Framework Single Crystal-Derived Nitrogen-Doped Hierarchical...

The biggest challenge of potassium-ion batteries (KIBs) application is to develop high-performance electrode materials to accommodate the potassium ions large size. Herein, by rational design, we carbonize three-dimensional (3D) ordered macroporous ZIF-8 to fabricate 3D interconnected nitrogen-doped hierarchical porous carbon (N-HPC) that shows excellent rate performance (94 mAh g^-1 at 10.0 A g^-1), unprecedented cycle stability (157 mA g^-1 after 12000 cycles at 2.0 A g^-1), and superior reversible capacity (292 mAh g^-1 at 0.1 A g^-1). The 3D hierarchical porous structure diminishes the diffusion distance for both ions/electrons, while N-doping improves the reactivity and electronic conductivity via producing more defects. In addition, the bicontinuous structure possesses a large specific surface area, decreasing the current density, again improving the rate performance. In situ Raman spectra analysis confirms the potassiation and depotassiation in the N-HPC are highly reversible processes. The galvanostatic intermittent titration measurement and first-principles calculations reveal that the interconnected macropores are more beneficial to the diffusion of the K⁺. This 3D interpenetrating structure demonstrates a superiority for energy storage applications.