Cobalt-Based Catalyst Integration Into a Hierarchically Ordered Macro-Meso-microporous Carbon Cathode for...

The pyrolytic synthesis of an ordered macro-meso-micro porous carbon cathode material (OM-PC) with integration of a Co₃ZnC/Co catalyst is reported. It is derived from a Co-doped ZIF-8 framework via a templated in situ growth within the interstitial spaces of a preformed self-assembled polystyrene monolith, followed by the template removal. The hierarchical 3D architecture facilitates Zn²⁺ diffusion and enhances reaction kinetics during charge-discharge processes. The integrated Co₃ZnC/Co catalyst significantly improves the surface affinity of the porous carbon host for polysulfide trapping and accelerates polysulfide redox conversion, leading to enhanced sulfur utilization, mitigated shuttle effects, and longer cycling stability. The fabricated aqueous Zn-S battery with the sulfur-loaded cathode denoted as S@Co₃ZnC/Co/OM-PC delivers a synergistic high discharge capacity of ≈1685 mA h g-¹, which includes ≈115 mA h g^-1 contributed from the I₃ ^-/I^- redox couple. The device shows low polarization and exhibits a minimal capacity decay of ≈0.027% per cycle over 400 cycles. It maintained a good rate performance of ≈1035 mA h g^-1 at 3 A g^-1, with long cycling stability. In-depth investigation reveals a multistep intermediate polysulfides conversion pathway in the aqueous electrolyte, which effectively avoids the sluggish solid-solid conversion.