The effect of water on the anodic dissolution of aluminum in non-aqueous electrolytes

The influence of water concentration on the electrochemical behavior of Al anodes in Al/active-non-aqueous electrolytes is investigated. Normally passive, Al exhibits facile electrochemical oxidation in both AlCl3/gamma-butyrolactone (AlCl3/BLA) and (C2H5)(4)NCl acetonitrile (TEAC/ACN) electrolytes. However, in these two electrolytes, the influence of water on Al oxidation shows opposite effects. Incremental increase from 0 to 1.5 M H2O (0 to 3% water by volume) hinders Al oxidation in 1 M AlCl3/BLA, increasing polarization loss from 100 to 400 mV cm(2) mA(-1). Yet in 0.3 M TEAC/ACN, Al is passive in the absence of water, exhibiting currents only in the mu A cm(-2) domain, equivalent to oxidative polarization losses of over 1000 mV cm(2) mA(-1). This polarization loss is alleviated by water addition, and decreases from 20 to 7 mV cm(2) mA(-1) as water is increased from 0.3 to 1.5 M. FT-IR spectroscopy, linear voltammetry, galvanostatic reduction, surface microscopy and electrolytic conductivity measurements were conducted to probe competing water activation or water passivation effects on organic-phase Al electrochemistry. (C) 2000 Elsevier Science S.A. All rights reserved.