Defect-Rich In2S3/CoS2 Heterostructure for Rapid Storage of Sodium Ions

Aiming to accelerate sodium-ion transport kinetics and improve electrochemical cyclability of batteries, an In₂S₃/CoS₂ bimetallic sulfide heterostructure was synthesized as anodes of sodium-ion batteries (SIBs) in this paper by a feasible ion exchange and subsequent hydrothermal vulcanization technique based on a cobalt metal-organic skeleton (ZIF-67) precursor. As-prepared In₂S₃/CoS₂ composite exhibited an excellent rate capability of 453.8 mAh g^-1 at 10 A g^-1 and outstanding cyclability of 464.06 mAh g^-1 after 600 cycles at 2 A g^-1. The built-in electric filed between heterogeneous interface of In₂S₃ and CoS₂ plays a dominant contribution on improvement of electronic conductivity and charge transfer kinetics. Beyond that abundant defects derived from ion exchange and nanocrystallization of composite particles also have a positive synergistic effect on inducing additional active centers for adsorption of Na⁺ and shortening ion transport distance for further accelerating reaction kinetics. Based on exploring conversion and alloying mechanism of In₂S₃/CoS₂ composite via ex situ XRD and TEM, high-performance SIBs with heterostructure bimetallic sulfide anodes may be a prospective strategy.