A nitrogen doped carbonized metal-organic framework for high stability room temperature sodium-sulfur batteries

A nanoporous nitrogen doped carbon matrix was prepared by carbonization of metal-organic framework zeolitic imidazolate framework (ZIF-8) precursors. The doped carbon matrix was melt-infiltrated with sulfur to form a carbonized ZIF-8/S composite. The composite material exhibited good performance as the cathode for room-temperature sodium-sulfur battery (Na-S) systems. A reversible specific capacity of around 1000 mA h g^-1 could be achieved at a rate of 0.1C; and a reversible specific capacity of 500 mA h g^-1 was obtained at a rate of 0.2C after 250 cycles. The good performance of the Na-S battery could be attributed to the synergistic effect from the nanoporosity of the carbon matrix and the high nitrogen-doping content (ca. ∼18 at%). These attributes enhanced the entrapment of the sulfur molecules inside the carbon matrices.