Fe3O4/Fe2N heterostructured hollow microspheres as functional electrocatalysts for high stability lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) are considered as a promising candidate for next-generation energy storage devices due to the high theoretical capacity, giant energy density , affordability, and environmental friendliness . However, the notorious shuttle effect and poor redox kinetics of lithium polysulfide (LiPS) tremendously hinder their commercial application. Herein, we have developed a Fe 3 O 4 /Fe 2 N heterostructure by growing Fe 2 N in situ on the surface of Fe 3 O 4 hollow microspheres as a cathode electrocatalyst . This heterostructure effectively integrates the immobilization of sulfur species and reinforced redox transformation kinetics, enhancing the high-rate capability and reversible cycling lifetime. The Fe 3 O 4 hollow microspheres enhance chemisorption sites and inhibit the shuttle of polysulfide . Meanwhile, incorporating Fe 2 N significantly accelerates the kinetics and thermodynamics of multistep polysulfide redox reactions . These advantages are confirmed through operando characterizations and electrochemical tests, demonstrating enhanced adsorption interactions and accelerated LiPS redox reactions . Also, this configuration provides excellent conductivity and enables high charge transfer efficiency. Leveraging these merits, a coin cell assembled with Fe 3 O 4 /Fe 2 N heterostructure shows a decent initial capacity of 1128.37 mAh g −1 at 0.2 C, while the reversible capacity over 100 cycles attained 900.34 mAh g −1 . Furthermore, the average specific capacity fade is as low as 0.0391 % per cycle after 1000 cycles at 1 C. A distinctive Fe 3 O 4 /Fe 2 N heterostructures were prepared via a straightforward hydrothermal strategy followed by calcination process. This heterostructure effectively integrates the strong LiPS adsorption capability of Fe 3 O 4 with the rapid phase transformation kinetics of Fe 2 N. The Li-S batteries assembled with S/Fe 3 O 4 /Fe 2 N cathodes achieved an initial specific capacity of 1128.37 mAh g −1 at a rate of 0.2 C and maintained a reversible discharge capacity of 900.34 mAh g −1 after 100 cycles. • A distinctive Fe 3 O 4 /Fe 2 N heterostructures effectively integrates the strong LiPS adsorption capability of Fe 3 O 4 with the rapid phase transformation kinetics of Fe 2 N. • This configuration demonstrates enhanced conductivity compared to pure Fe 3 O 4 sulfur hosts, enabling high charge transfer efficiency. • The Fe 3 O 4 /Fe 2 N cathode demonstrated excellent cycling stability with an ultra-low capacity decay rate of 0.0391 % per cycle after 1000 reversible cycling at 1 C.