Enhanced anchoring and catalytic conversion of polysulfides by iron phthalocyanine for graphene-based Li-S batteries

Rechargeable lithium-sulfur (Li-S) batteries are seriously limited by low sulfur utilization and sluggish electrochemical reaction activity of polysulfide intermediates exacerbated by the detrimental shuttle effect. Herein, a strong mitigation toward lithium polysulfides (LiPSs) adsorption/catalysis is achieved by introducing iron phthalocyanine (FePc) as an effective additive for high-performance graphene-based Li-S batteries. The reduced graphene oxide (rGO) acts as conductive infrastructure to ensure adequate electron transport and smooth electrolyte accessibility, while the additional conjugate molecule functions as active sites to accelerate the reactions kinetic, enhance the conversion process, and thus effectively inhibit the shuttling of LiPSs. By coupling FePc with rGO through pi-pi stacking interaction, the fabricated electrode with 10 wt.% of FePc exhibits a high initial discharge capacity (1307 mAh g(-1) at 0.1 C) and a superior cyclic stability (a low capacity fading rate of 0.049% per cycle over 500 cycles at 0.5 C). The proposed hybridization strategy will offer new ways for achieving high-stable and long-lifetime Li-S batteries.