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.