Layered double hydroxide derived cobalt-iron sulfide heterostructures with enhanced reaction kinetics for use in sodium-ion batteries

Abstract

Constructing a well-designed heterojunction on anodes of sodium ion batteries (SIBs) is an essential strategy for developing high-performance Na-storage devices. In this study, a CoS1.097/FeS lamellar heterostructure was built via a simple two-step hydrothermal treatment using layered double hydroxide precursors. The as-prepared sample exhibits a hydrotalcite-like intercalated structure and heterogeneous composition, which boosts the electrochemical reaction kinetics by shortening the transport distance, unifying move direction and accelerating mobility of Na+. Meanwhile, benefited from such advantages as additional active sites at surfaces, enhanced internal structure stability and relaxed stress from volume expansion etc., SIBs with as-prepared CoS1.097/FeS heterojunction anodes shows excellent sodium storage performances，including high rate capability (564.1 mAh g-1 at 10 A g-1), good the initial coulombic efficiency (80.65% at 0.5 A g-1) as well as great cyclability (543.9 mAh g-1 at 2 A g-1 after 450 cycles). Theoretical calculations based on the first principles are carried out to clarify the possible sodium storage mechanisms. The job may provide a feasible route and key technologies through structural designing and surface coating to prepare anode materials for high-performance sodium-ion batteries. It is expected that the current work can be extended to build other advanced electrode materials for various energy storage related applications.