Dear friend Mata Prasad Sharma

I appreciate your thoughtful inquiry into the factors influencing the consistency of battery charging and discharging behavior. Your question raises important considerations about the internal mechanisms that may contribute to these undulations, such as ion movement and temperature variations within the battery structure.

Indeed, the internal architecture—including electrode composition, electrolyte properties, and separator design—can significantly impact ion transport and thermal stability. Fluctuations in these parameters often manifest as irregular charging or discharging patterns. To investigate further, I would suggest controlled experiments that monitor temperature gradients, ion diffusion rates, and voltage profiles under varying operational conditions. Techniques such as electrochemical impedance spectroscopy or in-situ thermal imaging could provide valuable insights.

In terms of potential solutions, exploring alternative materials with higher ionic conductivity or improved thermal management properties may help stabilize performance. Adjustments in cell design, such as optimizing electrode thickness or enhancing separator efficiency, could also mitigate these fluctuations.

I would be interested to hear your thoughts on which experimental approaches you find most promising, or if you have specific hypotheses regarding material or design modifications. Please let me know how you would like to proceed, and if you would be open to a collaborative investigation.

Best regards,

Kaushik

It would be useful to see the voltage/current graph too. Your x-axis units are also a bit strange to me.. mAh/g? What batterly chemistry is this? Is this a pack of several cells? I'm trying to figure it out based on the min/max voltage but I cant figure it out, it seems strange. If it is a small pack, perhaps there is a passive balancing system causing the undulation? Otherwise it would seem like an issue with your power supply (not keeping constant current) and/or measurement device to me. I assume you are charging at constant current?

It is not the problem with the measuring technique, as I have made this LNMO electrode and tested it with the lithium metal as an anode. The long curve seen here is for the first charge of the coin cell. Here I am getting the undulation, but I don't know why I am getting that. What have I done wrong? I didn't get it. is it because of water, etc.? I want to know so I can try to solve this problem. Generally, the GCD curves are smooth.

Well, you see what seems to be a relaxation curve/behavior in each undulation which (to me) indicates that the current delivered to the cell is halted or decreased during this period. This is why I suspect you power supply or the system controlling the current has an issue.

Alternatively there could there be some connect/disconnect behavior or a high impedance which builds up in your cell as you charge which then decreases again as the current drops.

Are you measuring the voltage at the cell terminals and is the current measured in/at the power supply terminals? Or are these measured at the same points?

It may be that the electrolyte is not compatible, but could the occurrence of this situation below 4V be related to problems in battery assembly?

Weiya Libut, why am I getting this in the first cycle only, not in other cycles?

So I was thinking, is this because the CEI is not stable or because there is water in the electrolyte.