Atomically Dispersed Manganese Electrocatalyst for Efficient Solid–Solid Conversion in Li–Se Battery

Abstract

Selenium-based cathodes represent an attractive alternative to sulfur for high-energy-density lithium batteries owing to their high intrinsic electrical conductivity, superior active material utilization, and enhanced volumetric capacity. Unlike sulfur, selenium cathodes in carbonate electrolytes undergo a direct solid–solid conversion with negligible polyselenide dissolution, offering an intrinsic pathway to suppress the shuttle effect. However, the sluggish kinetics and high energy barriers associated with this conversion necessitate the rational design of catalytic reaction interfaces. Here, we demonstrate a metal-organic framework-derived manganese single-atom catalyst anchored to nitrogen-doped carbon (Mn-NC) that fundamentally regulates the selenium conversion pathway in Li–Se batteries. The Mn-NC host, synthesized via Mn²⁺ incorporation into ZIF-8, features a hierarchical bimodal pore architecture and atomically dispersed Mn active sites stabilized within a defect-rich nitrogen–carbon matrix. These structural attributes synergistically enable uniform selenium confinement, improved Se-host adherence, and accelerated Se redox kinetics, offering discharge capacities of 508 and 333 mAh g^–1 at 0.1 and 5 C, respectively. Density functional theory (DFT) analyses substantiate that Mn–N₄ centers significantly lower the energy barriers for Se₈ ↔ Li₂Se conversion, induce strong chemisorptive interactions with Se, and promote fast, reversible solid-state redox processes. The present work establishes a general strategy for engineering solid–solid chalcogen conversion pathways using atomically precise active centers. Furthermore, the in situ incorporation of earth-abundant Mn single atoms into a template-free hierarchical carbon host provides a potentially scalable route toward advanced chalcogen-based energy storage systems.