I have difficulty figuring out what exactly is the SEI layer in the battery field. I am trying to find out how it is formed and its function and influence on battery.
I appreciate having your experience and knowledge.
Dear Dr. Erfan Omid,
I suggest you to have a look at the following note/paper:
-The Effect of an SEI Layer on Anode and Cathode Particles
Available at: https://www.forgenano.com/education/effect-sei-layer-anode-cathode-particles/
-Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries
Wang, A., Kadam, S., Li, H. et al
npj Comput. Mater. 4, 15 (2018) –Open access
Available at: https://www.nature.com/articles/s41524-018-0064-0
Best regards, Pierluigi Traverso
Dear Erfran
To my experience it is one of the most important things to understand int he battery field, depending on your active material used. It is formed as a difference between the chemical potentials from anode, cathode and the electrolytes to passivate the electrodes. Usually it is composed of decomposition productions or dissociation products from solvents or salts. Most important is the thickness of the sei layer as it might lead to diffusion problems. If you have silicon I recommend you also "Corset-like solid electrolyte interface for fast charging of silicon wire anodes" from my co authors and me.
Dear Erfan,
I am most familiar with the SEI term for lithium anode primary (non-rechargeable) batteries. In the case of Li/SOCl2 cells, the electrolyte is formed from LiAlCl4 as salt and thionyl chloride as the solvent. SOCl2 is also reduced on discharge preducing exceptioally high specific energy. The cell voltage is 3.68V at room temperature so the solvent (ie catholyte) is very reactive.
Fortunately, the solvent and metallic lithium react with in 1msec on filling the cell, thus forming an SEI layer of LiCl about 100 Angstroms thick. The SEI acts as a passive film on the lithium, halting any further reaction. When initially discharged, lithium ions tunnel through the SEI to balance the thionyl chloride reduction, forming S and SO2 at the porous carbon cathode. Elevated temperatures on storage as well at repeated intermittent discharge can lead to increases in the SEI thickness. When the cell is discharged, the thick, resistive SEI results in a voltage drop (IR loss) until the film breaks up. This can take minutes to seconds, depending on the cell's history and cell load. Hope this helps your research. Others can address the many other applications of the term "SEI".
Robert C. McDonald
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