Rational construction of heterostructured core-shell Bi2S3@Co9S8 complex hollow particles toward high-performance Li- and Na-ion storage

The development of hollow structures with structural and composition complexity are highly attractive in the field of energy storage. In the present work, we demonstrate the rational construction of unique heterostructured core-shell Bi2S3@Co9S8 complex hollow particles (CHPs) through a facile metal-organic framework (MOF)-engaged strategy, in which the Bi2S3 spheres are well confined in the Co9S8 multi-cavity hollow shells. Benefiting from the specific structural and composition advantages, the core-shell Bi2S3@Co9S8 CHPs exhibit remarkable Li- and Na-ion storage performance in the aspects of high reversible capacity, excellent rate performance and longterm cycling stability. Electrochemical analyses reveal fast reaction kinetics in the core-shell Bi2S3@Co9S8 CHPs. Meanwhile, a Bi2S3@Co9S8//LiFePO4 full cell is successfully fabricated to evaluate their potential for real applications. In addition, the possible reaction mechanisms of the core-shell Bi2S3@Co9S8 CHPs for both Li- and Na-ion storage have been investigated via ex situ X-ray diffraction technique. Furthermore, density functional theoretical calculations confirm the heterostructure in the Bi2S3@Co9S8 CHPs can enhance the electrical conductivity and reaction kinetics. This work may offer new opportunities for integration of two active anode materials with high capacity and electrochemical activity into one heterostructured complex hollow structure.