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

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Developing high-performance cathode materials is crucial for advancing aqueous zinc-sulfur (Zn-S) batteries.
• The shuttle effect of polysulfides and sluggish reaction kinetics hinder the practical application of Zn-S batteries.

Purpose of the Study:

• To synthesize an ordered macro-meso-micro porous carbon cathode material (OM-PC) integrated with a Co3ZnC/Co catalyst for aqueous Zn-S batteries.
• To investigate the synergistic effects of the hierarchical porous structure and the catalyst on battery performance.

Main Methods:

• Pyrolytic synthesis of OM-PC using a templated in situ growth method within a polystyrene monolith.
• Incorporation of a Co3ZnC/Co catalyst derived from a Co-doped ZIF-8 framework.
• Fabrication and electrochemical testing of aqueous Zn-S batteries utilizing the S@Co3ZnC/Co/OM-PC cathode.

Main Results:

• The hierarchical 3D architecture of OM-PC facilitates Zn2+ diffusion and enhances reaction kinetics.
• The Co3ZnC/Co catalyst effectively traps polysulfides and accelerates their redox conversion, mitigating the shuttle effect.
• The S@Co3ZnC/Co/OM-PC cathode delivered a high discharge capacity of ~1685 mA h g-1 (including ~115 mA h g-1 from I3-/I- redox couple) with low polarization.
• The battery exhibited minimal capacity decay (~0.027% per cycle) over 400 cycles and maintained good rate performance (~1035 mA h g-1 at 3 A g-1).

Conclusions:

• The developed cathode material demonstrates excellent electrochemical performance for aqueous Zn-S batteries.
• The combination of hierarchical porosity and the Co3ZnC/Co catalyst provides a promising strategy for high-sulfur-utilization and long-cycling-stability batteries.
• The study reveals a multistep polysulfide conversion pathway that avoids sluggish solid-solid conversion, enhancing overall battery efficiency.