A MnS/FeS heterostructure with a high degree of lattice matching anchored into carbon skeleton for ultra-stable sodium-ion storage

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2021-11, Vol.9 (42), p.2424-2435
• Main Authors: Yue, Luchao, Wu, Donghai, Wu, Zhenguo, Zhao, Wenxi, Wang, Dong, Zhong, Benhe, Liu, Qian, Liu, Yang, Gao, Shuyan, Asiri, Abdullah M, Guo, Xiaodong, Ma, Dongwei, Sun, Xuping
• Format: Article
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d1ta06760e

Combining two different compounds into a heterostructure recently emerged as an auspicious strategy to mitigate the issues associated with the sluggish sodium diffusion kinetics of anode materials. Nevertheless, studies relating to as-designed heterostructures, so far, have not considered the matching of crystal structures between different compounds. In this work, a heterostructure between MnS and FeS 2 , featuring identical cubic systems and close lattice parameters, confined in one-dimensional carbon nanofibers was synthesized through electrospinning technology (denoted as MnS/FeS 2 @CNFs). An internal built-in electric field is generated at the interface of the heterostructure owing to differences in the bandgaps of the two compounds, and this is conducive to accelerating the Na + diffusion kinetics and enhancing charge transport. Meanwhile, the one-dimensional carbon skeleton can effectively alleviate volume variations and prevent the aggregation of active material during the sodium storage process. As expected, the MnS/FeS 2 @CNFs composite delivered good rate performance (322.3 mA h g −1 at 10.0 A g −1 ) and excellent cycling durability (194.0 mA h g −1 at 10.0 A g −1 over 3600 cycles). In line with DFT calculations, the constructed heterojunction with a small mismatch of ∼3.9% can effectively enhance the electronic conductivity of the composite, thereby accelerating charge transfer. This work can help the development of rational design strategies for heterostructures and provide an in-depth understanding of the functions of heterostructures in the energy-storage field. Taking their similarities in crystal structures and close lattice parameters into consideration, cubic pyrite FeS 2 and MnS were used to construct a heterostructure for achieving synchronous improvements in specific capacity and rate performance.