High-Capacity Aqueous Storage in Vanadate Cathodes Promoted by the Zn-Ion and Proton Intercalation and Conversion–Intercalation of Vanadyl Ions

• Published in: ACS applied materials & interfaces Vol. 13; no. 22; pp. 25993 - 26000
• Main Authors: Kim, SaeWon, Shan, Xiaoqiang, Abeykoon, Milinda, Kwon, Gihan, Olds, Daniel, Teng, Xiaowei
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 09.06.2021; American Chemical Society (ACS)
• Subjects: aqueous batteries; cation conversion−intercalation; ENERGY STORAGE; Energy, Environmental, and Catalysis Applications; tri-ion intercalations; vanadium redox; zinc-ion batteries; zinc-ion batteries; aqueous batteries; tri-ion intercalations; vanadium redox; cation conversion−intercalation
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.1c04279

Aqueous Zn-ion batteries (AZIBs) are promising alternatives to lithium-ion batteries in stationary storage. However, limited storage capacity and cyclic life impede their large-scale implementation. We report reversible electrochemical insertion of multi-ions into sodium vanadate (NaV3O8) cathode materials for AZIBs, achieving a maximum storage capacity of 450 mAh g–1 at 0.05 A g–1 and a capacity retention of 82% after 500 cycles at 0.4 A g–1. In addition to Zn2+ and H+ insertion, in situ X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) collectively provide explicit evidence on vanadyl ions (VO2+) conversion–intercalation at the NaV3O8 cathode, showing the deintercalation of VO2+ from NaV3O8 and the consequent conversion of VO2+ into V2O5 on charging, and vice versa on discharging. Our study is the first to report on the cation conversion–intercalation mechanism in AZIBs. This reversible multi-ion storage mechanism provides a design principle for developing high-capacity aqueous electrode materials by engaging both the intercalation and conversion of charge carriers.