I can run a CV with my Mg cell which delivers peaks indicating the presence of oxidizing and reducing procceses. When I try to perform a galvanostatic charging/discharging the voltage almost immediately rises/drops to the boundary value and no current can enter the cell or can be drawn from it.
How can this be understood? May it be a polarization phenomenon? Do you have any suggestions on how to circumvent this?
My cell setup:
Anode: Mg metal
Electrolyte: Mg(TFSI)2 in glyme/diglyme
Cathode: MoS2 (should definitely accomodate Mg)
Yes, it is due to the polarization. You might want to modify your question about the "CV" technique, or even you might try to run a potentiostatic charging/discharging test (instead of "CV") as a more close "analog" formal case to your galvanostatic charging/discharging test.
Hi, try a lower current density during charge/discharge. How sharp/broad the redox peaks are in your CV profile?
I also thought that a lower current density could help out, so I decreased it to even 0.01C, but still no charging occurs.
The redox peaks are relatively broad, unfortunately I don't have an example image here right now.
Thank you everyone for your answers! In the meantime I figured out that indeed a large polarization (as mentioned by Ioannis) was the issue. When using TFSI/glyme-based electrolytes without further ingredients this polarization is nearly 2V. Adjusting the charge/discharge boundary potentials solved it.
- Badges
- Science topic
- Similar topics
- Chemistry
- Electrochemistry