关键词: 低共熔溶剂, 钒离子, 电化学, 温度效应, 电解质

Abstract:

Compared with conventional aqueous electrolyte, deep eutectic solvent(DES) has been studied as the electrolyte of flow battery for its unique advantages. However, its physical and electrochemical properties are more sensitive to the temperature and related researches can hardly be found in open literature. The aim of the work is to study the physical and electrochemical properties of vanadium ions in DES through varying the operating temperatures. The curves of cyclic voltammetry indicate that vanadium ions show a quasi-reversible reaction. As the temperature increased from ambient temperature to 55℃, the difference between oxidation and reduction peaks decreases from 0.271 V to 0.249 V at the scan rate of 100 mV·s^-1. At the same time, both the anodic and the cathodic peak current densities of the V(Ⅱ)/V(Ⅲ) have the similarly incremental trend. The conductivity also has an obvious increment from 2.2 mS·cm^-1 at ambient temperature to 11.16 mS·cm^-1 at 55℃, but the viscosity of DES vanadium ions have a huge drop. The results prove that the operating temperature plays a vital effect on the characteristics of DES and it deserves a further study.

Key words: deep eutectic solvent, vanadium ion, electrochemistry, temperature effect, electrolytes