I am using LMNO as cathode, LTO anode, LI -reference and LP30 electrolyte. The cell is cycled in the 0.1C rate in the voltage range(3.5V to 5V). I am getting a black layer over my lithium reference. Does it come from the reaction with electrolyte or is it due to lack of air tightness? In those cells with the layer over Li RE, the capacity reduces after three or four cycles.
1) What are the Voltages Vj, from the, as prepared cells, 2 classes[yes / no] ?
Note1 for classes : yes / no black layer
Note2 (say V-marks as) :V1=Cathode-Anode, V2R=Cathode-LiRef,
2) Q:Does it affect the impedance measurement? Yes, a lot.
3) Do you have any Eis, from the 2 classes?
Hello sir,
I think my question was not clear so I have edited it now. For your questions, the Voltage range is 3.5V to 5V. I am developing a new test cell design for Swagelok cell, so the impedance data is not so reliable for time being and it has full of artifacts.
First you have to see how stable is you cathode and anode by doing cyclic voltammetry test with your electrolyte by having lithium as reference electrode. Different electrolyte species will be reduced to form different surface-film products.
Hi Raam,
How does it exactly look like for the "black layer", was it firmly coated to your Li metal, or loosely attached, more like a slurry? In my experience with coin type half-cell, when I disassemble cells that cycled for more than 100 cycles, I always can see lots of GREY slurry on Li metal side. For even more cycles, the whole Li metal will disappear and turned out to be the GREY slurry. This is mainly due to un-perfect Li deposition.
For your case, since your voltage is pretty high which make it hard for Li plating. So it is possible because of the side reactions with water and air, as what you thought. If your work station is near glovebox, the easiest way to check the sealing is to put the Swagelok cell inside glovebox during test. Or you can make several half cells to check the compatibility of your electrode and electrolyte.
In case Li metal is the problem, you can try to use other Reference electrode instead of Li, such as Pt.
Thank you both.
Mr. Chen, Mr.Bicaku,
The layer is loosely bound like a slurry. I will try to do it inside glove box to verify whether it is due to reaction with air. since I am using one side ring type electrode(12mm dia with 4mm hole) and reference in the center of the ring, CE somewhat more capacity without the hole(regular full 12mm dia electrode). Is it possible that it can be due to reaction between lithium and electrolyte?
Yes, can be. Q:Is it possible that it can be due to reaction between lithium and electrolyte?
Check it, in your GB.
Hallo Mr. Samaras,
I have made EIS for the above mentioned cell. it has a black layer. I am getting some artifacts and I have enclosed the impedance spectra.