Operando STM study of the interaction of imidazolium-based ionic liquid with graphite

Journal Article · Tue Nov 27 00:00:00 EST 2018 · Energy Storage Materials

DOI:https://doi.org/10.1016/j.ensm.2018.11.026· OSTI ID:1604690

Wang, Huixin ^[1]; Wu, Cheng Hao ^[2]; Eren, Baran ^[2]; Hao, Yibo ^[2]; Feng, Bingmei ^[1]; Fang, Hai-Tao ^[3]; Salmeron, Miquel ^[4]

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1. Harbin Inst. of Technology (China); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
3. Harbin Inst. of Technology (China)
4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)

Understanding interactions at the interfaces of carbon with ionic liquids (ILs) is crucially beneficial for the diagnostics and performance improvement of electrochemical devices containing carbon as active materials or conductive additives in electrodes and ILs as solvents or additives in electrolytes. The interfacial interactions of three typical imidazolium-based ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (AMImTFSI) ILs having ethyl (C₂), butyl (C₄) and octyl (C₈) chains in their cations, with highly oriented pyrolytic graphite (HOPG) were studied in-situ by electrochemical scanning tunneling microscopy (EC-STM). The etching of HOPG surface and the exfoliation of graphite/graphene flakes as well as cation intercalation were observed at the HOPG/C₂MImTFSI interface. The etching also takes place in C₄MImTFSI at -1.5 V vs Pt but only at step edges with a much slower rate, whereas C₈MIm⁺ cations adsorbs strongly on the HOPG surface under similar conditions with no observable etching or intercalation. Finally, the EC-STM observations can be explained by the increase in van der Waals interaction between the cations and the graphite surface with increasing length of alkyl chains.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: Harbin Institute of Technology; National Natural Science Foundation of China (NNSFC); Swiss National Science Foundation (SNF); USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 1604690
• Alternate ID(s): OSTI ID: 1637218
• Journal Information: Energy Storage Materials, Journal Name: Energy Storage Materials Journal Issue: C Vol. 20; ISSN 2405-8297
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
electrochemical scanning tunneling microscope
graphite
imidazolium
ionic liquids