Electrocodeposition of lithium and copper from room temperature ionic liquid 1-ethyl-3-methyllimidazolium bis(trifluoromethylsulfonyl)imide

Abstract

1-Ethyl-3-methyllimidazolium bis(trifluoromethylsulfonyl)imide ([EMIm][TFSI]) ionic liquid containing Li(I), and [EMIm][TFSI] with N-methyl-2-pyrrolidone (NMP, volume ratio 2 : 1) containing Cu(II) and mixtures of Li(I) and Cu(II) was studied using cyclic voltammetry at 298 K. NMP was used to increase the solubility of Cu(II) in the [EMIm][TFSI]. The underpotential deposition (UPD) of lithium was observed at about −2.0 V (vs. Pt). Electrodeposits of Li–Cu with different atom content of Li can be obtained by controlled-potential electrolysis. The XRD and XPS results show that the deposit consists of metallic lithium and copper. The Li–Cu alloy coatings obtained in this study were compact and adherent, and it was clearly found that there was Cu framework left after dissolving deposited Li in distilled water.