Silicon oxycarbide-derived hierarchical porous carbon nanoparticles with tunable pore structure for lithium-sulfur batteries

초록

Most lithium-sulfur (Li-S) batteries have limited practical commercialization owing to extremely low S loading, insufficient cycle stability, and poor rate capability despite their high theoretical capacity. Herein, Li-S batteries with outstanding electrochemical performance under high S loading mass are achieved from hierarchical porous carbon nanoparticles (hPCNs) prepared via a scalable spray pyrolysis process. HPCNs are synthesized from organosilanol precursors, which contains phenyl and hydroxyl groups attached to silicon facilitating SiOxCy, SiO4, and carbon nanonetwork formations. SiOxCy and SiO4 phases can produce abundant micro-and mesopores, respectively, using template method. Consequently, hPCNs show high surface area (2789 m2 g- 1) and pore volume (2.31 cm3 g- 1) allowing large amount of sulfur to be accommodated efficiently. When hPCN is applied as a multifunctional sulfur host, micropores can suppress lithium polysulfide dissolution, whereas mesopores can accommodate a large amount of sulfur, improving the energy density of the Li-S battery. In addition, the carbon nanonetworks improve redox kinetics with their excellent electrical conductivity. Therefore, sulfur-infiltrated hPCNs show a high initial capacity of 1229 mA h g- 1 and a capacity retention of 74% after 400 cycles at 1C rate.

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