image: Generalized strategy for constructing interfacial covalent bonds at the interface of carbon nanostructures with VS4 nanorods to enhance magnesium storage capability
Credit: ©Science China Press
This study is led by Prof. Xiaosi Zhou and Dr. Yichen Du (School of Chemistry and Materials Science, Nanjing Normal University). CNTs/VS4 with novel chain-like morphology were synthesized by solvothermal method. ABF-STEM and X-ray absorption near-edge structure were utilized to characterize the composite. In addition, ex situ characterization and theoretical calculations confirmed the ion deposition mechanism in CNTs/VS4.
VS4 has a unique layered atomic chain structure and has the potential to become a high-performance magnesium-ion battery cathode material with high capacity and long cycle life. However, low conductivity and sluggish Mg2+ diffusivity during cycling limit its practical application in large-scale energy storage. Herein, we use a solvothermal approach and utilizing P123 surfactant to in situ construct V–O–C covalent bonds between VS4 nanorods and surface oxidized CNTs interfaces.
“There are many carbonyl groups on the surface of oxidized CNTs, during the solvothermal process, the V source was absorbed on the surface oxidized CNTs, nucleated on the CNTs, and reacted to generate VS4. Raman and XPS tests confirmed the presence of the V–O–C covalent bonds at interface, which promoted the tight bonding between VS4 and CNTs, helping to maintain structural stability during cycling, thereby extending cycle life. Additionally, ex situ characterization and theoretical calculations confirmed the reversible deposition of Mg2+ and MgCl+, further reduced the polar barrier for divalent ion transport.” Zhou says.
In summary, this rationally designed architecture promotes ion diffusion and electron transfer, thus facilitating reaction kinetics. CNTs/VS4 exhibits excellent magnesium storage properties, including a high reversible capacity of 223.2 mAh g−1 at a current density of 50 mA g−1, a remarkable discharge capacity of 91.8 mAh g−1 even at 2000 mA g−1, and an impressive capacity retention of 85.2% after 1000 cycles at 500 mA g−1. Moreover, this cooperative assembly-oriented strategy can be used as a versatile method to creatively obtain various VS4/carbon nanocomposites with unique morphological structures, and provides a new approach for the development of transition metal sulfide/carbon composite electrode materials.
See the article:
A universal cooperative assembly-oriented strategy for VS4 nanorods decoration on carbon nanostructures with enhanced magnesium storage properties
https://doi.org/10.1007/s11426-024-2195-2
Journal
Science China Chemistry