Solid electrolyte interphase formation on metallic lithium
[ 1 ] Instytut Chemii i Elektrochemii Technicznej, Wydział Technologii Chemicznej, Politechnika Poznańska | [ E ] pensioner | [ P ] employee
2012
scientific article
english
- Lithium
- SEI
- Electrolyte additive
- EIS
EN Solutions of three salts (LiBF4, LiNTf2, LiPF6) in N-methyl-2-pyrrolidone (NMP), selected arbitrarily as a reference solvent, were investigated by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy techniques. The lithium surface in contact with LiPF6 in NMP electrolyte was covered with a protective layer (SEI) which morphology comprise small particles (of ca. 0.2 μm in radius). This salt was selected for further studies. The impedance of the Li|(LiPF6 in NMP+additive)|Li system was measured immediately after cell assembly and after galvanostatic charging/discharging. Fifteen different additives (10 wt.%) were used. The efficiency of individual additives was evaluated in terms of the Li|electrolyte system resistance (ΔR) or total cell impedance reduction, both deduced from EIS. Some of the additives were able to form the SEI layer and to reduce resistance/impedance of the Li|electrolyte interphase. In such cases, the lithium surface was covered with relatively uniform conglomerates, or regions separated by cracks, of ca. 1–2 μm in dimension.
08.06.2012
3391 - 3397
public
2,279