Effect of Li Ions on Al Electrodeposition from Dimethylsulfone

Abstract

The influence of LiCl coexistence with Al electrodeposition was investigated in a dimethyl sulfone, DMSO 2 , bath containing AlCl 3 at 403 K. The electrochemical behaviors of Li and Al ions were examined using Pt electrodes in the bath and the deposition mechanism was analyzed by cyclic voltammetry, CV, with an Al reference electrode in the bath. The coexistence of LiCl in the AlCl 3-DMSO 2 bath inhibited the cathodic current corresponding to Al deposition in the CV experiment. The amount of ca. 500 μmol Al deposits was obtained in constant potential electrolysis for 1 h at-2 V in the bath with 10 mol% AlCl 3. However, it decreased to 140 μmol Al in the bath with 10 mol% AlCl 3 and 5 mol% LiCl. It was clarified that LiCl addition led to the formation of Li(DMSO 2) + more than the formation of () 3 2 3 Al DMSO + from NMR measurement for the baths. This results in the suppression of Al deposition because LiCl inhibits the formation of () 3 2 3 Al DMSO + complex ions, which is said to be necessary for Al electrodeposition.

Effect of Ammonium Salts on the Conductivity and Current Efficiency of Dimethyl Sulfone-Aluminum Chloride Electrolytes

“…27 Furthermore, Kim reported that the intensity of the Al(DMSO 2 ) 3 3+ signals decreased upon adding LiCl to the electrolyte. 39 These results indicate that the addition of NR 4 Cl decreases the concentration of the Al 3+ species in the electrolyte involved in the Al electrodeposition, such as the solvated form of Al(DMSO 2 ) 3 3+ . Based on the results of 27 Al NMR spectroscopy, we discuss the change in the dissociation equilibrium of the ionic species in the electrolyte upon adding NR 4 Cl.…”

“…In contrast, sulfonebased solvents [25][26][27][28] have low volatility and inflammability. For example, dimethyl sulfone ((CH 3 ) 2 SO 2 , DMSO 2 ) [29][30][31][32][33][34][35][36][37][38][39][40][41] is inexpensive, compared to ionic liquids, and it can facilitate film formation with a current density of 50 mA cm −2 or more. However, since the melting point of DMSO 2 is 109 °C, the processing temperature is higher than those of other organic solvents.…”

“…Much research has been performed on DMSO 2 -AlCl 3 based electrolytes. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] Most of them are studied at temperatures greater than 110 °C. The main reason 110 °C or higher is selected is because the melting point of DMSO 2 , a solvent, is 109 °C, so we must study phenomena at temperatures greater than the melting temperature of the solvent.…”