Constructing defect-rich unconventional phase Cu7.2S4 nanotubes via microwave-induced selective etching for ultra-stable rechargeable magnesium batteries

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 430; p. 133108
• Main Authors: Yang, Xinyu, Du, Changliang, Zhu, Youqi, Peng, Hui, Liu, Bolin, Cao, Yuehua, Zhang, Yuexing, Ma, Xilan, Cao, Chuanbao
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.02.2022
• Subjects: Cathode; Cu7.2S4 nanotubes; Lattice defect; Microwave synthesis; Rechargeable magnesium batteries; Microwave synthesis; Cathode; Lattice defect; Rechargeable magnesium batteries; Cu7.2S4 nanotubes
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2021.133108

The defect-rich unconventional phase Cu7.2S4 Nanotubes are fabricated by a facile microwave-induced selective etching method. Benefitting from the unique one-dimensional crystal structure and lattice defect-rich hollow structure, the Cu7.2S4 nanotubes exhibit high reversible capacity and remarkable cycling stability. [Display omitted] •The defect-rich Cu7.2S4 nanotubes are fabricated for the first time.•The unique microwave-induced selective etching method is demonstrated.•The record cycling stability is achieved over the Cu7.2S4 nanotube cathode.•The multistep reaction kinetics of the Cu7.2S4 nanotube cathode are confirmed. Copper sulfide is promising great potential for capable cathode in rechargeable magnesium batteries. However, divalent Mg2+ diffusion in its host lattice is subject to high lattice strain and mechanical stress mainly due to strong Coulombic interaction. Herein, a microwave-induced selective etching strategy is reported to construct non-stoichiometric-phase robust Cu7.2S4 nanotubes with rich lattice defects, which can proceed with ultra-long-cycling stability over 1600 cycles with ultra-low capacity decay of 0.0109 % per cycle at 1.0 A g−1. Furthermore, the Cu7.2S4 nanotube cathode can also exhibit a large specific capacity of 314 mAh g−1 at 0.1 A g−1 as well as an excellent rate capability of 91.7 mAh g−1 at 1.0 A g−1. The present electrochemical performances greatly surpass those of Cu7.2S4 nanowire, Cu7.2S4 nanoparticle, and conventional phase CuS nanotubes and at least are comparable to the conversion-type cathode materials reported so far. The generated lattice defect combined with the optimized robust nanotube structure can effectively buffer lattice strain and mechanical stress to provide a favorable diffusion kinetic. Our designed microwave-induced selective etching system demonstrates significant superiority in morphology, phase, and defect engineering of Cu7.2S4 nanotubes to accommodate reversible Mg2+ storage for high-performance rechargeable magnesium batteries.