Construction of an adsorption-diffusion model reveals the conversion-deposition process of polysulfides

Despite progress in suppressing polysulfide shuttling, this challenge persists in lithium-sulfur battery commercialization. While existing strategies emphasize polysulfide adsorption and catalytic conversion, the critical role of diffusion kinetics in conversion–deposition processes remains underexplored. We design an MXene-based array architecture integrating 2D structural advantages and strong polysulfide affinity to regulate diffusion pathways. Combined experimental and multiscale computational studies reveal diffusion-mediated conversion-deposition dynamics. The sodium alginate-constructed MXene array enables three synergistic mechanisms: (1) Enhanced ion/electron delocalization reduces diffusion barriers, (2) Continuous ion transport channels facilitate charge transfer, and (3) Exposed polar surfaces promote polysulfide aggregation/conversion. Synchrotron X-ray tomography coupled with comprehensive electrochemical analyses reveals distinct mechanistic differences between conversion and deposition processes arising from diffusion heterogeneity. In situ characterization techniques combined with DFT simulation calculations demonstrate that diffusion kinetics exerts differential regulatory effects on these coupled electrochemical processes, exhibiting particular sensitivity toward the deposition mechanism. This work provides fundamental insights that reshape our understanding of diffusion-mediated phase transformation in complex multi-step electrochemical systems, offering new perspectives for advanced electrode architecture design in next-generation energy storage technologies. By constructing MXene array structures, the adsorption and diffusion kinetics of polysulfides during their transformation-deposition processes are synergistically regulated, thereby achieving a continuous and stable sulfur reaction closed-loop mechanism. • The array structure regulation introduces a diffusion factor to clarify the conversion-deposition effect of diffusion on polysulfides. • In-situ characterization and electrochemical tests show that the diffusion-adsorption process of soluble polysulfides in the electrode is balanced, and the generation of Li 2 S insulating layer is reduced. • Studies have shown that diffusion can promote the deposition-transformation of polysulfides in the multi-step solid-liquid-solid multi-phase conversion process, and achieve the ‘closed-loop effect’ of the reaction.