Polyethylene Glycol–Na+ Interface of Vanadium Hexacyanoferrate Cathode for Highly Stable Rechargeable Aqueous Sodium-Ion Battery

• DOI: 10.1021/acsami.9b04849
• Publication Date: 2019-07-18T14:31:39Z
• Authors: Ping Jiang; Zhenyu Lei; Liang Chen; Xuecheng Shao; Xinmiao Liang; Jun Zhang; Yanchao Wang; Jiujun Zhang; Zhaoping Liu; Jiwen Feng
• Keywords: Sodium-ion battery

Vanadium hexacyanoferrate (VHCF) with an open-framework crystal structure is a promising cathode material for rechargeable aqueous metal-ion batteries owing to its high electrochemical performance and easy synthesis. In this paper, vanadium cathodes were first used constructing sodium-ion (VHCF/WO3) tested in the new-type electrolyte (NaP-4.6) consisting of polyethylene glycol (PEG)/H2O/NaClO4 low H+ concentration (molar ratio [H2O]/[Na+] 4.6), which has stability at current density as 1000 mA g–1 capacity retention 90.3% after 2000 cycles coulombic efficiency (above 97.8%). To understand their outstanding performance, proton-assisted storage mechanism interphase chemistry VHCF are investigated by solid-state NMR (ssNMR) technology. It suggested that reaction accompanied redox atoms Na+ intercalation iron atoms. also observed complex (PEG) (PEG–Na+) exists on surface, facilitates promotes alkali-ion transfer density. The results ssNMR study offer new insights into Prussian blue analogues open-framework-structured compounds, can greatly broaden our horizons battery research.