Operando synchrotron X-ray studies of MnVOH@SWCNT nanocomposites as cathodes for high-performance aqueous zinc-ion batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2022-07, Vol.1 (27), p.1454-14554
• Main Authors: Gull, Sanna, Huang, Shao-Chu, Ni, Chung-Sheng, Liu, Shih-Fu, Lin, Wei-Hsiang, Chen, Han-Yi
• Format: Article
• Language: English
• Subjects: Cathodes; Electrode materials; Electrode polarization; Electron transfer; Energy storage; Interlayers; Low temperature; Nanocomposites; Rechargeable batteries; Single wall carbon nanotubes; Spectroscopy; Storage batteries; Storage capacity; Synchrotron radiation; Synchrotrons; X ray absorption; X-ray diffraction; Zinc
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d2ta02734h

Aqueous zinc-ion batteries (AZIBs) have great potential as energy-storage devices because of their low cost and environmental friendliness. However, the key challenge for rapid and reversible Zn 2+ for AZIBs is the generation of a stable and efficient cathode material. Herein, we prepared a scalable synthesis method, based on a low-temperature (120 °C) hydrothermal route, to prepare Mn 0.19 V 2 O 5 ·2.34H 2 O (MnVOH), which was incorporated into a single-walled carbon nanotube (SWCNT) network, and subsequently utilized as the AZIB cathode material. Furthermore, the MnVOH@SWCNT nanocomposite material ensured close interaction between MnVOH and SWCNTs, with a continuous network structure, and expanded interlayer spacing that provided fast electron transfer kinetics ( D Zn 2+ : 10 −11 to 10 −12 cm 2 s −1 ). This resulted in an excellent rate performance of 81% during cycling. Consequently, the resultant batteries possessed a significantly enhanced intercalation storage capacity of 381 mA h g −1 , at a current density of 0.1 A g −1 , and reduced polarization with a high capacity retention of 89% over 300 cycles (at 5 A g −1 ). Furthermore, operando synchrotron X-ray absorption near-edge spectroscopy (XANES) was studied for the first time to verify the Zn 2+ charge-storage mechanism. To further understand the structural changes of the MnVOH@SWCNT nanocomposite during the discharge/charge process, operando synchrotron X-ray diffraction (XRD) measurements were also performed. In addition, the MnVOH@SWCNT nanocomposite material could sustain a high energy density of ca. 194 W h kg −1 at a high-power density of 3.2 kW kg −1 , which is higher than that of MnVOH, thus demonstrating that MnVOH@SWCNTs is a promising candidate as a high-performance cathode material for AZIB applications. MnVOH@SWCNTs shows a high capacity up to 381 mA h g −1 over 300 cycles. Operando XANES confirms the change in oxidation states and operando XRD shows the reversible change in the crystal structure during the cycling process.