Self-assembled nanoflower ZIF-carbon for superior sodium storage

Conventional hard carbon anodes, despite their high sodium storage capacity, suffer from two major limitations: sluggish ion diffusion kinetics due to tortuous micropore networks and significant volume expansion arising from disordered carbon structures. These inherent defects collectively compromise rate capability and cycling stability. Herein, we devise a graphene oxide (GO)-directed templating approach to architect ZIF-derived carbon into a hierarchical nanoflower superstructure with radially aligned meso/macroporous nanosheets. This superstructure integrates three synergistic features: 3D interconnected channels and graphitic domains enabling fast ion/electron transport, radially aligned nanosheets maximizing electrode-electrolyte contact while accommodating volume expansion, and nitrogen-doped defect sites providing preferential redox-active centers for sodium storage. The optimized ZIF-9@GO-6 achieves a high specific capacity of 521.8 mAh g−1 at 0.05 A g−1 with an initial Coulombic efficiency of 89.2%, and retains a specific capacity of 298.2 mAh g−1 after 500 cycles. This GO-directed morphological engineering strategy effectively resolves the intrinsic trade-offs between porosity, conductivity, and structural stability in conventional hard carbon anodes, paving the way for scalable, high-performance sodium-ion batteries.