The effect of Celgard 2400, Celgard 2500, ENTEK ET20-60, TEKLON UH2054 and glass fiber separator on BMImBF₄ ionic liquid containing 0.5 mol•L^－1 Mg(CF₃SO₃)₂ as the electrolyte of magnesium deposition-dissolution was studied. Scanning electron microscopy, absorption performance, AC impedance and constant current charge-discharge measurements were conducted to analyze the surface structure of separators, absorption and maintenance of electrolyte, ionic conductivity and magnesium deposition- dissolution process in coin cells, respectively. The results indicated that the glass fiber separator was more suitable for magnesium deposition-dissolution in Mg(CF₃SO₃)₂/BMImBF₄ electrolyte, especially at high current densities due to better absorption and maintenance performances, and higher ionic conductivity.

Key words: ionic liquids, BMImBF₄, separators, electrochemical deposition and dissolution, magnesium batteries