Self-templated formation of hierarchically yolk–shell-structured ZnS/NC dodecahedra with superior lithium storage properties

Abstract

Hierarchical ZnS/NC dodecahedra are successfully constructed via a two-step synthetic method combining a sulfidation process and subsequent carbonization treatment, benefiting from the inherent merits of zeolitic imidazolate frameworks as ideal precursors/self-sacrificing templates. Studies reveal that the sulfidation time plays a vital role in the morphological evolution and lithium storage performances of final products. To our knowledge, this is the first example of carbon-based ZnS hierarchical materials with yolk–shell structures. When used as anode materials for lithium-ion batteries (LIBs), the resultant ZnS(x h)/NC (x is the sulfidation time) electrodes showed high lithium storage abilities, excellent cycling stabilities, and good rate capabilities. The optimal ZnS(72 h)/NC sample shows a well-defined multi-yolk–shell structure and delivers a high reversible specific capacity (757 mA h g⁻¹ after 100 cycles at 200 mA g⁻¹), extraordinary rate capability, and intriguing long-term cycling stability (∼500 mA h g⁻¹ at 2 A g⁻¹ after 1000 cycles). Such a type of architecture simultaneously integrates several attractive design principles for high-performance LIB anodes including the yolk–shell structure, nitrogen-doped carbon coupling, and ultrafine ZnS nanoparticles.