Zinc-ion batteries (ZIBs) based on near-neutral aqueous electrolytes represent a promising large-scale energy storage solution for deeper and broader penetration of clean renewable energy because of their outstanding merits in energy density, cost, and eco-friendliness.
Realizing rapid and reversible Zn2+ storage at the cathode is imperative for the advancement of aqueous ZIBs, which offer an option for large-scale electrochemical energy storage. However, owing to limitations of the structural stability of previously investigated frameworks, the Zn2+ storage processes remain unclear.
Recently, a research group led by Prof. YANG Weishen and Dr. ZHU Kaiyue from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) presented the novel application of MoVTe oxide with an M1 phase (MVT-M1) as potential cathode materials for ZIBs and conducted atomic scale analysis of Zn2+ storage process in MVT-M1.
This study was published in Chemical Science on July 27.
MoVTe oxide with M1 phase for storing Zn2+ (Image by ZHU Kaiyue)
The researchers found that MVT-M1 featured broad and robust tunnels that facilitated reversible Zn2+ insertion/extraction during cycling, as well as rich redox centers (Mo, V, and Te) to aid in charge redistribution, resulting in good performances in ZIBs.
Due to the exceptional resilience of MVT-M1 to high-energy electron beams, they directly observed Zn2+ insertion/extraction at the atomic scale within the tunnels using high-angle annular dark field scanning transmission electron microscopy. Moreover, they determined the storage location of zinc ions within the cathode layer by layer from the surface to the bulk phase by employing time-of-flight secondary ion mass spectrometry. Additionally, solvent molecules, including H2O and methanol, were also found inside the tunnels along with Zn2+.
"Our results are helpful to understand the Zn2+ storage mechanism and enable the design of novel materials specifically optimized for efficient Zn2+ storage," said Prof. YANG.
The above work was supported by the National Natural Science Foundation of China and the Youth Innovation Fund of DICP.