Electrochemical reaction of lithium alanate dissolved in diethyl ether and tetrahydrofuran

We present electrochemical properties of lithium alanate (LiAlH4) dissolved in aprotic ethers – diethyl ether (Et2O) and tetrahydrofuran (THF) – under an Ar atmosphere of 1 atm at 298 K. Specific conductivities of both LiAlH4–THF and LiAlH4–Et2O solutions are measured by AC four-terminal method. Cyclic voltammetry is performed with using a beaker-type electrochemical cell consisted of a Ni wire, Ni mesh and Li wire as a working, counter and reference electrode, respectively. In order to clarify the electrochemical behavior, anodic polarization of LiAlH4–THF solution is measured. The current density of 1.0 M LiAlH4–THF solution reaches to 1 A cm−2, which is higher than the LiAlH4–Et2O solution. Quantitative analysis of H2 gas generated on the working electrode during the potentiostatic electrolysis tells that the number of electrons involved in the anodic reaction at the limiting current is one in case of the LiAlH4–THF solution. We propose conceivable electrochemical reactions of LiAlH4 in the non-aqueous ethereal solutions.