I have prepared a solid polymer electrolyte (SPE) with PVDF-HFP and LiTFSI in acetone and NMP and the dried the films under vacuum at 80 oC for 24h to make a solvent free SPEs. To obtain a Gel-polymer electrolyte (GPE), few microliters of EC:DEC were dropped over the SPE while fabricating the NCM523/GPE/Graphite full cells. When running the GCD measurements at 0.1 C in a potential window of 2.7-4.2 V, I am facing kind of polarization during the charging curve above 3.9 V vs Li/Li+. The corresponding graphs have been attached for the reference. What causes this polarization during charging above 3.9 V vs. Li/Li+? If anyone have idea about this problem, please give your valuable suggestions. it would be a great help. Thanks in advance.
Thank you for your answer Toma Stankulov
I have added 10 microliters of electrolyte to make a gel-electrolyte on 1.6 cm of SPE. It's a CR2023 coin cell. May be that would be one of the possible reasons, I guess too.
Dear Syam Kandula ,
try to reduce[1] the parameter of the Vhigh (GC limit) on (super)charging (semi-cycle) phase, since the electrolyte of the cell seems to be decomposed and (progressively, upon more 'charging') is desiccated (dry[2]) the electrolyte, upon '(super)charging' beyond the extreme (GC limit) Vhigh, near, or next to, the (used) intense value, 4.10 V.
1. Reduce the V.high parameter during 'charging'. A new alternative/proposal (safer) might be the (less intense) V.high value, 4.05 V.
2. Upon '(super)charging': Gel-polymer electrolyte (GPE) --> 'Dry-polymer (poor) electrolyte'
Dear Ioannis Samaras ,
Thank you so much for your valuable suggestions.
I'll reduce the voltage cut-off to lower value and will repeat the experiments.
Regards,
Syam
Dear Syam Kandula ,
make (and use) a new[1] class of fresh ('unsmoked') cells.
1. The old cell(s) are substandard (second-class), due to 'Dry-polymer (poor) electrolyte'.
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