Intercalant-induced V t2g orbital occupation in vanadium oxide cathode towards fast-charging aqueous zinc-ion batteries

Title	Intercalant-induced V t2g orbital occupation in vanadium oxide cathode towards fast-charging aqueous zinc-ion batteries
Authors	Yixiu Wang, Shiqiang Wei, Zheng-Hang Qi, Shuangming Chen, Kefu Zhu, Honghe Ding, Yuyang Cao, Quan Zhou, Changda Wang, Pengjun Zhang, Xin Guo, Xiya Yang, Xiaojun Wu, Li Song
Magazine	Proceedings of the National Academy of Sciences of the United Kingdom
Date	03/20/2023
DOI	10.1073/pnas.2217208120
Introduction	Intercalation-type layered oxides are being studied extensively as cathode materials for aqueous zinc-ion batteries (ZIBs). While high-rate capabilities have been attained by using various intercalants to widen interlayer spaces, the atomic orbital changes induced by these intercalants are not yet fully understood. In this study, we developed NH4+-intercalated vanadium oxide (NH4+-V2O5) for high-rate ZIBs and conducted an in-depth investigation into the role of the intercalant regarding atomic orbitals. Our X-ray spectroscopy analyses show that NH4+ insertion promotes electron transition to the 3dxy state of the V t2g orbital in V2O5, which significantly enhances electron transfer and Zn-ion migration, a finding further supported by DFT calculations. Consequently, the NH4+-V2O5 electrode demonstrates a high capacity of 430.0 mA h g−1 at 0.1 A g−1, along with excellent rate capability (101.0 mA h g−1 at 200 C), allowing for fast charging within 18 seconds. Moreover, the reversible V t2g orbital and lattice space variations during cycling were observed through ex-situ soft X-ray absorption spectrum and in-situ synchrotron radiation X-ray diffraction, respectively. This research offers valuable insights into the advanced cathode materials at the orbital level.
Quote	Yixiu Wang, Shiqiang Wei and Zheng-Hang Qi et al. Intercalant-induced V t2g orbital occupation in vanadium oxide cathode towards fast-charging aqueous zinc-ion batteries. Proceedings of the National Academy of Sciences of the United States of America. 2023. Vol. 120(13). DOI: 10.1073/pnas.2217208120
Element	Vanadium (V) , Zinc (Zn) , Nitrogen (N)
Materials	Oxides
Topics	Energy Materials
Industry	Energy Storage & Batteries