Exploring high-performance magnesium-sulfur pouch cells using nitrogen-rich doped nano porous carbon

Magnesium-sulfur batteries (MSBs) are promising due to Mg's lower propensity to form dendrites, its natural abundance, and high volumetric energy densities for large-scale energy storage. Nonetheless, Mg²⁺ ions have poor diffusion kinetics and the magnesium polysulfide (MgPS) shuttle effect present significant challenges for MSBs. Herein, a Mg-S pouch cell is designed using rich N-doped porous carbon (ZIF8-NC) and a Cu current collector. This architecture provides numerous benefits: i) ZIF8-NC offers a conductive skeleton that significantly enhances electron and Mg²⁺ ion conduction, ii) zeolite imidazolate frameworks (ZIF-8) derived N rich sites demonstrate superior MgPS anchoring capability, iii) the Cu collector not only accelerates conversion of anchored MgPS to MgS, but also participates in the electrode reaction and iv) the material is easy to synthesize on a large scale, facilitating its potential for practical applications. Mg-S/ZIF8-NC coin cells maintain ∼310 mAh·g^-1 after 1000 cycles even at 1C. Furthermore, Mg-S/ZIF8-NC pouch cells achieve high cathodic energy densities of ∼120 Wh·kg^-1 and ∼330 mAh·g^-1 after 300 cycles at 1C, outperforming the state-of-the-art results in the literature. Soft X-ray absorption spectroscopy (sXAS) revealed that the initial catalytic reaction of Cu follows Cu⁰↔Cu₂S, and later Cu₂S↔Cu_xS. Theoretical calculations and experimental results reveal that pyridine nitrogen acts as catalytic site for polysulfide adsorption. Therefore, this work not only provides a facile method to prepare high-performance Mg-S pouch cells, but also proposes mechanisms whereby N active sites and Cu catalytic reactions promote all aspects of performance.