Solution activators of aluminum electrochemistry in organic media

The use of solution activators (dissolved metal salts) to enhance aluminum electrochemical activity in organic media is reported. Aluminum is electroc hemically passive in most organic electrolytes and unlike lithium, has not been developed as a battery anode in organic media. We demonstrate signific ant Al activity in two electrolytes, AlCl3 in gamma-butyrolactone or (C2H5) (4)NCl in acetonitrile. These improve the anodic potential by up to 1 V in comparison to other electrolytes and increase from microampere to milliampe re per square centimeter, the sustainable Al oxidation current. Electrolyti c metal acetate, chloride, or other salts can further enhance these favorab le anodic characteristics. Unlike Sn(II), Sn(IV), or Ga(III), both Hg(II) a nd In(III) significantly activate Al redox behavior. In 1 M AlCl3/gamma-but yrolactone, the Al oxidative polarization is 100,65. 36, or only 28 Ohm cm( 2) in electrolytes containing, respectively, 0, 1: 10, 100 mM Hg(II). Hg(II ) also shifts negatively the observed E(Al)degrees by 150 to 250 mV, an enh ancement sustained during extended anodic galvanostatic discharge. Similarl y, as little as 1 mM In(III) diminishes polarization to 1 0 Ohm cm(2) Addit ion of 10 mM In(II) to 0.3 M (C2H5)(4)NCl in acetonitrile, improves E(Al)de grees by 0.4 to -157 V vs. I-3-/I. (C) 2000 The Electrochemical Society. S0 013-4651(99)06-089-9. All rights reserved.