Highly Synergistic Physicochemical Constraints of NaBr@Carbonized ZIF-8 Cathode Enable Efficient and Stable Sodium-Ion Storage

Suppressing the shuttle effect of bromine is essential for achieving high-energy-density long-cycle brominated sodium-ion batteries. Here, we propose a synergistic constraint strategy that combines physical confinement and chemical adsorption and design a NaBr@carbonized ZIF-8 cathode architecture via a simple NaBr dissolution-adsorption-recrystallization process. The obtained structure features abundant NaBr nano-crystallines uniformly embedded within carbonized ZIF-8 frameworks, forming a multi-core encapsulated composite. Systematic studies disclose synergistic physical and chemical interactions between NaBr and carbonized ZIF-8. Compact physical confinement alleviates volume change and electrolyte erosion, and robust chemical adsorption facilitates fast electron and ion transport and also stabilizes bromine active species. Owing to the improvement in the electrical, chemical, and volumetric properties, the composite design enables promising electrochemical performance, including a high reversible capacity of 254 mAh g⁻¹ at 1 C, an excellent rate capability of 148 mAh g⁻¹ at 10 C, and an outstanding capacity retention of 86% after 1000 cycles at 10 C. A synergistic physicochemical constraint strategy offers a promising pathway toward durable, high-performance Na–Br batteries, underscoring their potential for large-scale energy storage applications.