General Synthesis of Dual Carbon-Confined Metal Sulfides Quantum Dots Toward High-Performance Anodes for Sodium-Ion Batteries

5 years ago

General Synthesis of Dual Carbon-Confined Metal Sulfides Quantum Dots Toward High-Performance Anodes for Sodium-Ion Batteries

Renbing Wu, Dalin Sun, Yun Song, Yanhui Guo, Xuebin Yu, Hongbin Xu, Miao Liu, Fang Fang, Hao Wang, Ziliang Chen

Sponge-like composites assembled by cobalt sulfides quantum dots (Co9S8 QD), mesoporous hollow carbon polyhedral (HCP) matrix, and a reduced graphene oxide (rGO) wrapping sheets are synthesized by a simultaneous thermal reduction, carbonization, and sulfidation of zeolitic imidazolate frameworks@GO precursors. Specifically, Co9S8 QD with size less than 4 nm are homogenously embedded within HCP matrix, which is encapsulated in macroporous rGO, thereby leading to the double carbon-confined hierarchical composites with strong coupling effect. Experimental data combined with density functional theory calculations reveal that the presence of coupled rGO not only prevents the aggregation and excessive growth of particles, but also expands the lattice parameters of Co9S8 crystals, enhancing the reactivity for sodium storage. Benefiting from the hierarchical porosity, conductive network, structural integrity, and a synergistic effect of the components, the sponge-like composites used as binder-free anodes manifest outstanding sodium-storage performance in terms of excellent stable capacity (628 mAh g−1 after 500 cycles at 300 mA g−1) and exceptional rate capability (529, 448, and 330 mAh g−1 at 1600, 3200, and 6400 mA g−1). More importantly, the synthetic method is very versatile and can be easily extended to fabricate other transition-metal-sulfides-based sponge-like composites with excellent electrochemical performances. Sponge-like composites assembled by Co9S8 quantum dots, hollow carbon polyhedra, and 3D reduced graphene oxide (GO) network are fabricated by a simultaneous thermal reduction, carbonization, and sulfidation of zeolitic imidazolate frameworks@GO precursors. Benefiting from the hierarchical porosity, conductive network, structural integrity, and synergistic effect of components, the composites used as binder-free anodes exhibit high specific capacity, good rate performance, and outstanding cycling stability in sodium-ion batteries.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adfm.201702046