In Situ Sulfidation‐Derived NiFe‐LDH/Ni ₃ S ₂ Heterojunction Catalyst Enabling Reversible LiOH Reaction Pathway in High‐Performance Li‐O ₂ Batteries

Abstract LiOH with superior chemical stability and high conductivity as the discharge product of lithium‐oxygen (Li‐O 2 ) batteries has attracted significant attention, which delivers a 4e − /O 2 process to support higher theoretical energy density. However, it remains a great challenge to achieve reversible deposition/decomposition of LiOH. Herein, a NiFe‐LDH/Ni 3 S 2 heterostructure catalyst is synthesized via an In Situ partial sulfidation process to drive the LiOH reaction pathway in Li‐O 2 batteries. Abundant cationic vacancies are introduced into the NiFe‐LDH matrix during the low‐temperature partial sulfidation, which triggers the catalytic activity of LDH plane. Meanwhile, the work function difference between NiFe‐LDH and Ni 3 S 2 induced a built‐in electric field, boosting the interfacial electron transport and charge redistribution to optimize the d‐band center and catalytic activity. Crucially, the interlayer H 2 O molecules and ─OH groups of NiFe‐LDH are confirmed to act as stable proton donors to promote the electro‐catalytic conversion from O 2 to LiOH through a 4e − pathway. As a result, the Li‐O 2 battery with NiFe‐LDH/Ni 3 S 2 catalyst delivered a high discharge capacity of 32 926 mAh g −1 at 200 mA g −1 and a stable cycle life of 794 cycles at 1 A g −1 . This work offers new insights into the design of advanced catalysts for LiOH‐based Li‐O 2 batteries.