Interfacial mechanochemical reaction synthesizes alkynyl porous carbon to firm cyclic lithium-sulfur batteries

Abstract

Due to the high theoretical discharge capacity and energy density, lithium-sulfur batteries have received lots of interest. However, the low sulfur utilization rate and quick capacity reduction are arisen out of the weak electrical conductivity of sulfur and the shuttle effect of polysulfides. Alkynyl-based porous carbon are prepared by interfacial mechanochemical reaction with CaC2 and C6Br6 as raw materials. The influence of the ratio of raw materials on the pore-structure of alkynyl-based porous carbon is investigated. The obtained APC-51 with a specific surface area (462.745 m2 g−1) has graded porosity structure and a relatively high carbon content (63.30 wt%). The initial discharge specific capacity of the lithium-sulfur battery assembled by APC-51/S as the positive electrode is 1017.0 mAh g−1 at 0.1 C and remains 720.6 mAh g−1 after 100 cycles. The prepared alkynyl-based porous carbon allows both physically and chemically adsorb on polysulfides assigned to its graded porosity structure and alkynyl functional groups.