| Cycling Performance and Surface Chemistry of Si-Cu Anode in Ionic Liquid Battery Electrolyte Diluted with Dimethyl Carbonate |
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Cao Cuong Nguyen, Dong-Won Kim, Seung-Wan Song |
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Department of Fine Chemical Engineering & Applied Chemistry, Chungnam National University;Department of Chemical Engineering, Hanyang University;Department of Fine Chemical Engineering & Applied Chemistry, Chungnam National University; |
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| Abstract |
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Interfacial compatibility between the Si-Cu electrode and diluted ionic liquid electrolyte containing 50 vol.% of 1M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)/1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide (MPP-TFSI) and 50 vol.% dimethyl carbonate (DMC) in a lithium cell and dilution effect on surface chemistry are examined. ex-situ ATR FTIR analysis results reveal that the surface of the Si-Cu electrode cycled in the diluted ionic liquid electrolyte is effectively passivated with the SEI layer mainly composed of carboxylate salts-containing polymeric compounds produced by the decomposition of DMC. Surface species by the decomposition of TFSI anion and MPP cation are found to be relatively in a very low concentration level. Passivation of electrode surface with the SEI species contributes to protect from further interfacial reactions and to preserve the electrode structure over 200 cycles, delivering discharge capacity of > 1670 $mAhg^{-1}$ and capacity retention of 88% of maximum discharge capacity. |
| Key Words:
Rechargeable lithium batteries, Si-based anode, Diluted ionic liquid electrolyte, SEI layer |
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