Highly Graphitized Porous Carbon-FeNi₃ Fabricated from Oleic Acid for Advanced Lithium-Sulfur Batteries

Improving the electrical conductivity of sulfur, suppressing shuttle/dissolution of polysulfide, and enhancing reaction kinetics in Li-S batteries are essential for practical applications. Here, for the first time, we have used inexpensive oleic acid as a single carbon source, and have added commercial SiO₂ as a template to form a porous structure, whereas introducing Fe(NO₃ )₃ and Ni(NO₃ )₂ as catalysts to increase the degree of graphitization. Moreover, the dual metal salts Fe(NO₃ )₃ and Ni(NO₃ )₂ can also form FeNi₃ alloy, and our results show that FeNi₃ nanoparticles accelerate the kinetic conversion reactions of polysulfide. By virtue of the well-developed porous structure and high degree of graphitization, the highly graphitized porous carbon-FeNi₃ (GPC-FeNi₃ ) has high conductivity to ensure fast charge transfer, and the hierarchically porous structure facilitates ion diffusion and traps polysulfide. Thus, a GPC-FeNi₃ /S cathode displays excellent electrochemical performance. At current rates of 0.2 and 1 C, a cathode of the GPC-FeNi₃ /S composite with a sulfur content of 70 % delivers high initial discharge capacities of 1108 and 880 mA h g^-1 , respectively, and retains reversible specific capacities of 850 mA h g^-1 after 200 cycles at 0.2 C and 625 mA h g^-1 after 400 cycles at 1 C.