After assembling the coin cell (half cell), is there a way to detect/ predict the bad cell without charging the cell? So that we can reduce the possibility of coin cell getting explode during charging/discharging test or while performing CV.
Thank you all for your time.
EIS is a very useful technique for this, but is very sensitive to differences, so you may need to determine a range that is considered good.
Thank you so much Dr. Mahmood and Dr. Ketter for your suggestions.
Dr. Mahmood, i had a case where battery voltage OCV was measured 3 V for sodium ion after few hours of assembling coin cell. However if i look for capacitance its seems like zero. Discharging pretty quick (around 8 mins) even though i am discharging at 0.1C . How will you interpret this case?
Dr. Ketter, sorry can you explain about the differences you are talking about in detail?
A battery management system (BMS) is any electronic system that manages a rechargeable battery (cell or battery pack), such as by protecting the battery from operating outside its Safe Operating Area, monitoring its state, calculating secondary data, reporting that data, controlling its environment, authenticating it and / or balancing it
Dear Tiwari Vivek,
can you show, please, some indicative EIS graphs[1] for a "good" coin cell ?
Also, if possible, include, please, some initial EIS graphs for the (exploded) coin cell, before the "explosion"[2].
1. Include, please, the VDC polarization(s) or/and the SOC.
2. Include the parametric value(s) of the VDC polarization(s).
Thank you for your time respected researchers. Dr. Mahmood i will open and check it.
I apologize , the cell that got exploded was while performing CV, not EIS (corrected). It was my lab mate Li ion cell. Dr. Samaras i will be happy to send you the curve (of good cell) if you are still interested?
Fine. Also, show (or send), please, some CV graph(s) for the (exploded) coin cell, just before the "explosion".
Dear vivek
The easiest way to predict that a cell is assembled bad or good is OCV. However, if you know the CV behavior of the system, CV graph helps you alot about that issue.
Hello Dr. Mahmood,
I opened the coin cell battery and check the cathode material (That was showing Open Circuit Voltage around 2.5 V (vs Na/Na+) but was discharging pretty fast). It doesn't seem the electrode got dissolved in electrolyte as far i know. I have attached the picture of it.
I made another cell from the same coating (cathode electrode) , which gave me good curve for some cycle showing it has the property of hosting ions. So probably i mess up in assembly of the previous one?
I would suggest an EIS Test. with very limited current. Moreover i would monitorize the assembled cell with a FLIR Camera just in the period after the assembly in order to detect also limited temperature variation as sign of critical issues.
But it is
Upon charging/discharging CV tests of your Na half cell, then you increase the percentage of the nanosize Na-clusters in the Na negative electrode. Initially, in your Na half cell, the melting temperature of the Na bulk material is not dependent on its size (97.8°C : bulk Na). However, as the dimensions of a material decrease towards the atomic scale, the melting temperature scales with the material dimensions. The decrease in melting temperature can be on the order of tens to hundreds of degrees for metals with nanometer dimensions. So, upon CV cycling tests of your Na half cell, then the nanosize Na-clusters increases to a high percentage; and a nanosize-Na melting might occur at a much lower temperature (Ncritical) for a high power application (for EVs etc.).
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