Heterojunction Vacancies‐Promoted High Sodium Storage Capacity and Fast Reaction Kinetics of the Anodes for Ultra‐High Performance Sodium‐Ion Batteries

Abstract Transition metal sulfides as anode materials for sodium‐ion batteries (SIBs) have the advantage of high capacity. However, their cycle‐life and rate performance at ultra‐high current density is still a thorny issue that limit the applicability of these materials. In this paper, the carbon‐embedded heterojunction with sulfur‐vacancies regulated by ultrafine bimetallic sulfides (vacancy‐CoS 2 /FeS 2 @C) with robust interfacial C‐S‐Co/Fe chemical bonds is successfully synthesized and explored as an anode material for sodium‐ion battery. By changing the ratio of two metal cations, the concentration of anion sulfur vacancies can be in‐situ adjusted without additional post‐treatment. The as‐prepared…