Tuning the Conversion Mechanisms of Metal–Sulfur Batteries: From Nanostructures to Single Atoms

Rechargeable metal-sulfur (M-S) batteries (Li, Na, K, Al, Zn, Mg, Ca, Cu, Fe‑based) are promising alternatives to conventional lithium‑ion batteries, featuring high energy density and cost‑effectiveness. However, their advancement is severely hindered by the sluggish sulfur conversion kinetics and the notorious polysulfide shuttle effect of the sulfur cathode. Thus, rational design of catalytic cathode materials is pivotal to realizing the practical application of M-S batteries. This review first evaluates the practical viability of various M-S batteries, further delineates the chemical behavior and transformation processes of sulfide intermediates, and summarizes the theoretical methodologies for probing sulfur cathode conversion chemistry. Notably, three classic heterogeneous catalysis mechanisms, namely Langmuir-Hinshelwood, Eley-Rideal, and Mars-van Krevelen, are innovatively utilized to interpret the cathode catalytic behavior in M-S batteries for the first time. Following this, it elaborates on the rational design principles targeting the supports and active sites of catalytic cathode materials, ranging from nanostructured engineering to single-atom catalysis, aiming to further reinforce sulfur immobilization and accelerate redox reaction kinetics across various M-S systems. Furthermore, it highlights advances in characterization strategies for guiding rational material design and elucidating precise electrocatalytic mechanisms, and ultimately prospects the pivotal future research directions toward practical liquid and solid-state M-S battery systems.