Electrodeposition of Magnesium in Ionic Liquid at 150‐200 °C

Structural modification by adding Li cations into Mg/Cs-TFSA molten salt facilitating Mg electrodeposition

“…Itis emphasized here that the Mg-anion distance under the coexistence of Li + is approximately 10-15 % longer than that without Li + at around N Mg-N ~ 1.5, and thus the coexistence of Li + can increase the free volume around Mg 2+ in the TFSA molten salts, which would facilitate the Mg electrodeposition. Actually, it is already reported that Mg metal can be electrodeposited in the TFSA molten salts containing Li + and/or Mg 2+ 22,23. Therefore, our present finding is a considerably important concept in the TFSA molten salts, and would lead to further understanding of the correlation between their structures and electrochemical behaviors.…”

“…[15][16][17][18][19][20][21] Recently, the successful Mg electrodeposition by adding Li + in the TFSA molten salt is reported as well as the high safety and the outstanding electrochemical characteristics of Mg ion batteries. 22,23 A plausible structure model is required to examine the structural modication by adding Li + in alkali-TFSA molten salts, due to the lack of information on the coordination environment of Mg 2+ .…”

A new aspect of Chevrel compounds as positive electrodes for magnesium batteries

“…The operating temperature is a key parameter controlling the cation distribution in terms of kinetics and thermodynamics. In the previous works by Hagiwara et al 26 and Oishi et al, 27 CsTFSA-based ionic liquid is stable at an elevated temperature of about 150-200 C, and cathodic deposition and anodic dissolution of magnesium can be reversibly carried out in the electrolyte despite showing passivation. 27 Of course, since ionic liquids have no electroneutral solvent that can inltrate into the crystal without any redox reactions, they are candidates for use in Chevrel-phase positive electrodes.…”

“…4 shows the results obtained with the use of electrolytes for the magnesium battery, where we used a large molecule solvent, Mg(TFSA) 2 /triglyme electrolyte 24,25 and ionic liquid Mg(TFSA) 2 / CsTFSA electrolyte. 26,27 The CV prole associated with the electrodeposition of magnesium is shown in ESI Fig. S3.…”

“…4(f), and few Cs cations insert into the Chevrel crystal, probably due to the large diameter of Cs cations. Although it is known that sole deposition of magnesium is difficult to achieve in this electrolyte 28 (although the electrodeposition of Mg can be facilitated in Mg(TFSA) 2 /CsTFSA-LiTFSA electrolyte 26,27 ), we have thus conrmed the electrolytic dissolution of Mg cations and TFSA anions in the Mg(TFSA) 2 /CsTFSA electrolyte, and this is suitable for the investigation of positive electrode materials for MRBs in that the mobility of Mg cations can be signicantly enhanced at relatively high temperatures (around 150-200 C).…”