I am researching layered oxide anode materials for sodium-ion batteries.
In the last experiment, I manufactured a coin cell (CR2032) using a Na(Ni1/3Fe1/3Mn1/3)O2 anode and a sodium metal cathode and conducted a charge/discharge test. At this time, the positive electrode was produced by mixing the active material, conductive material, and binder in a ratio of 8:1:1 with NMP and coating it on Al foil. The electrolyte was 1M NaPF6 in EC:PC (1:1) with 2% FEC, and the separator was a glass fiber filter. The assembled cell was kept at 25 degrees for one day. Afterward, I set the voltage range to 2.0~4.0V and started charging at 0.1C.
However, when I checked two days later, the cell did not reach 4.0V during the first charging process. When I checked the charge/discharge curve, I found that it showed a tortuous curve around 3.5~3.8V and could not go up any further. Although this problem did not appear in all cells, it occurred intermittently in subsequent experiments.
Why does this happen? Is this phenomenon related to SEI formation, electrode wettability, electrolyte composition, or Na dendrite? I would like to get advice from people with similar experiences or related experts.
Hey there Sanghyun Lee! So, about your sodium-ion battery hiccup. Look, the first charging blues can be a real pain, and there are a few possibilities behind this roadblock.
First off, let's talk SEI formation. The Solid Electrolyte Interphase (SEI) could be misbehaving during that initial charge. If it's not forming properly, it might mess with the voltage, causing your tortuous curve.
Then there's electrode wettability. If the electrode isn't playing nice with the electrolyte, you're going to have a bad time. Double-check your materials and their interactions. Make sure they're getting along.
Now, electrolyte composition. That mix of 1M NaPF6 in EC:PC with 2% FEC — it's a bit finicky. Maybe the ratio needs tweaking, or the FEC percentage is throwing things off. Experiment with that a bit.
And Na dendrites, the troublemakers of the battery world. These little sodium needles can mess with your voltage, causing issues during charging. Keep an eye out for their unwanted growth.
Look, this is a tricky field, and sometimes it takes a bit of trial and error. You Sanghyun Lee might need to fine-tune your materials, processes, or both. If all else fails, reach out to others in the field or find those battery gurus who've faced similar headaches. Good luck with your research!
Hello
In general, the voltage is considered a little higher to continue charging and discharging according to the conditions given to the program. And also, if your samples include various additives, it can be said that it is not capable of reaching that voltage
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