Confining Sb2Se3 nanorod yolk in a mesoporous carbon shell with an in-built buffer space for stable Li-ion batteries

The yolk-shell structure, realized by various synthesis methods, exhibits unique morphology and structural properties, which is currently undergoing a transition from material production technology to energy storage applications. To design an anode for lithium ion batteries (LIBs), a buffer space is designedly built between the Sb2Se3 nanorod yolk and the mesoporous carbon shell to obtain a novel yolk-shell structure (i.e., Sb2Se3@void@C). The confined void space is created by using a sacrificial template (such as silica) and the mesoporous carbon shell is obtained from the pyrolysis of phenolic resin, which effectively improves the electrical conductivity and structural stability of Sb2Se3 anode materials for LIB. Both the void space in the yolk-shell structure and the mesoporous carbon shell can efficiently buffer the volume expansion during the repeated discharge-charge processes, and further maintain the structural integrity. Besides, the permeable mesoporous carbon shell facilitates the electrolyte infiltration into the void space to ensure enough contact area between the Sb2Se3 and electrolyte, which benefits the shortening of the diffusion paths of Li+ ions. As a result, the Sb2Se3@void@C anode exhibits a high reversible specific capacity of 404.8 mA h g(-1) at a rate of 1.0 A g(-1) for at least 200 cycles, and maintains an average capacity of 594.7 at a rate of 3.0 A g(-1). To further establish the detailed lithium storage behavior, in situ XRD is conducted to reveal the conversion reaction and alloying/dealloying reaction mechanisms. This research sheds light on yolk-shell structure designs with various morphologies to improve the electrochemical performance of energy storage materials.