Zn/Co-ZIF-derived bi-metal embedded N-doped porous carbon as anodes for lithium-ion batteries

In this work, the unique Zn-Co nitrogen-doped porous carbon (Zn-Co/NPC) polyhedrons have been successfully synthesized via pyrolysis of bimetallic zeolitic imidazolate frameworks (ZIFs) precursor under N2, wherein the metallic Co and Zn particles are dispersed in the porous carbon matrix. The obtained porous carbons show a high surface area (315.67 m2 g−1) and contain plenty of mesopores. The unique mesoporous structure benefits from either the carbonization of organic ligands and the catalytic effect of metallic Co in calcination process or the elimination of a certain amount of metal species in acid dissolution. As an anode material for lithium-ion batteries, the Zn-Co/NPC particles exhibit superior lithium storage capabilities with excellent cycling properties. It demonstrates a high discharge capacity of 970 mA h g−1 at 0.1 A g−1. Besides, a reversible capacity of 813.5 mA h g−1 was retained at a much higher current density of 0.5 A g−1 after 500 cycles. The enhanced electrochemical performance was attributed to the unique microstructure, nitrogen doping, and the synergistic effect of Zn and Co embedded in carbon matrix.