Interfacial Bridging Ni Single Atoms Catalyze Ultrafast and Highly Reversible Conversion Between MoS ₂ and Mo/K ₂ S for Potassium‐Ion Batteries

Conversion‐type MoS 2 anodes for potassium‐ion batteries typically suffer from sluggish kinetics and insufficient reversible conversion, which leads to rapid capacity decay. Herein, we report a hierarchical, carbon‐confined MoS 2 architecture featuring bridging‐type Ni single‐atoms (Ni‐ONC/MoS 2 @NC). These Ni single atoms bridge the MoS 2 and the intercalated carbon through S‐Ni‐O coordination, establishing efficient interfacial electronic transfer channels, thereby enabling fast bidirectional reaction kinetics with a high reversible conversion ratio of 85.7%. Both i n situ and ex situ characterizations, alongside theoretical calculations reveal that the S‐Ni‐O catalytic sites lower the K + diffusion barrier in MoS 2 . The hybridization between Ni‐3d and S‐3p orbitals effectively promotes K 2 S adsorption, weakens the K‐S bonds, and catalyzes K 2 S decomposition. Notably, the S‐Ni‐O sites undergo coordination reconstruction from S 3 ‐Ni‐O 1 to S 1 ‐Ni‐O 3 during cycling, which stabilizes the MoS 2 /carbon interface and prevents the deactivation of catalytic sites, thereby enabling fast and highly reversible conversion reactions. Consequently, the Ni‐ONC/MoS 2 @NC electrode delivers exceptional rate performance (255 mAh g −1 at 10 A g −1 ) and long‐term cycling stability (260 mAh g −1 after 1200 cycles at 1 A g −1 ). This study highlights the critical role of single‐atom bridging catalytic interfaces in regulating conversion‐type K + storage and offers a new pathway for designing highly stable and reversible anodes.