Good days, everyone.
I am curious about the changing color of electrolyte containing LiPF6 after keeping in the inert glove box (Nitrogen) maybe for 4-6 months. Has anyone experienced this situation, and could you give me some ideas about this?
It is possible. It would be better if you could mention your electrolyte composition.
For LiPF6, this could be due to the traces of moisture, which deteriorates the electrolyte and produces HF.
Good Question, LiPF6 in which medium preparing aqueous medium or organic medium , what is the pH of your electrolyte, these two may be the answers, if no what do you think, please post your Views
Vadim S. Gorshkov
Actually, only I used it since when I joined the company. However, the electrolyte was put in another glove box before moving to mine to mix with other additives. My co-worker got the electrolyte directly from the manufacturing company, and they did not give any more details about the status of electrolyte except for the manufacturing date.
An-Giang Nguyen It is LiPF6 in EC/EMC/DMC solvent. We measured the moisture content with KF titrator and surprisingly, it was only 5-6 ppm.
Kantharao Kancharla I did not check the pH, but I got your point. Since I imported new electrolyte from company, I will check the moisture content, pH to compare. Thanks a lot ^^
Hieu Nguyen
It is neither high nor low. This is why your electrolyte has just turned yellow and not dark brown. Of course, at that stage, your electrolyte will be more acidic. You can try adding molecular sieves to absorb water next time.
You can try to add a freshly cut (surface shining) Li-metal, as a fast indicator for the 'health' of your actual electrolyte. Note the time (in hours), that turns to (the naked eye) appear as non-shining metallic surface[1].
1. Reactive surface coating of metallic lithium and its role in rechargeable lithium metal batteries https://www.sciencedirect.com/science/article/pii/S0013468621015607