The bottle of the electrolyte solution was opened in the glove box and put some amount of it in a small container for temporary use. After each use, we close the container's head with parafilm tape. Moreover, there is another bottle of the electrolyte solution, that its bottle cap has not been opened yet. Under what conditions is it possible for the solution to spoil? 2. What solvents and in what volume of the solution have been used to prepare the electrolyte solution from LiPF6? Also, there are 3 bottles of NMP which have not been opened yet. Is it possible for the NMP to spoil?
There is an old rule among chemists - if in doubt about a reagent, then immediatelly throw it away (dispose it, etc.). The cost of research error is higher than the cost of a new reagent, and as a rule, the researcher realizes that he has done unnecessary / erroneous work only after a few months of hard work. At the same time, old reagents can be used for debugging the methodology (e.g. checking cells for leaks), some irresponsible applications, etc. You have to be especially watchful with the students, some are careful initially (many thanks to their mom, dad and all their relatives), others learn quickly, but some behave according to the principle "Après moi le déluge".
Dear Azad,
The question is confusing.
LiPF6 for battery application is usualy used with a mixed carbonate-based solvents. The most common electrolyte compositions are 1.0 M LiPF6 in EC:DMC or EC:EMC (1:1 wt.% or vol.%, EC is solid below 40 C), e.g. ethylene cabonate, dimethyl carbonate, ethyl methyl carbonate. Other solvent composition is possible.
NMP is used for batery slurry preparation, not in the electrolyte.
PVdF is a polymer used as binder in energy electrode materials.
Regarding stability of the electrolyte: is is very stable and not prone to any changes in the Ar-filled glovebox.
Here some thouts:
1) LiPF6 reacts with glass. Electrolyte should be stored in plastic or Al bottle.
2) If you use Li metal, then Ar-filled glovebox is needed, Li reacts with nitrogen forming form lithium nitride (black colored).
3) LiPF6 and carbonate solvents are very hydrophilic, and for energy storage applications requrie special drying (until below ~20 ppm of water content). Opening such solvent or electrolyte outside of a glovebox makes it rather not suitable for electrolyte preparation, unless it is a special dry room with controlled moisture content.
4) LiPF6 starts to decompose at >90 C.
Dear Ievgen
Thanks. I want to know that my materiala have expired after 3 years or not?
Electrolye solution is in the glove box and after each using, we close the head of that and is stored in Al bottle.
Also, we have three plastic bottle of NMP that we have not used them yet.
Are these materials usable after 3 years?
Electrolyte should have expiration date. Oxidizing and reducing agents could affect its state of oxidization, that may lead to its decay or decrease in its shelf life.
I thinks, NMP is fine, electrolyte should be fine if the [H2O] in the glovebox was kept below 5 ppm and the electrolyte was closed.
In fact, commercial electrolytes from Sigma-Aldrich eleveted both [O2] and [H2O] levels in our glovebox with 0.8/0.8 ppm levels when I opened them for the 1st time. So, keeping them open them for a while is perfectly fine. I open every new battery grade chemical and keep it open for a day in the dry glovebox to revove traces of oxygen and moisture (they are always there).
Dear Nasrin Azad,
NMP (not opened) should be fine, after 3 years.
However, I would ask for a new electrolyte (LiPF6), after 3 working[1] years, after 3 years of commom (good) treatment.
1. Nasrin Azad's quote: Electrolyte solution is in the glove box and after each using, we close the head of that and is stored in Al bottle.
Dear Ioannis Samaras
Thank you.
How about a bottle of electrolyte that its head has been not opened yet after 3 years, and has stored in a fridge, is it proper to use?
Dear Nasrin Azad ,
I guess it might be proper to use.
However, I would start some diagnostic pre-tests, before a commom use.
A 'very fast', and simple, diagnostic pre-test is to add[1], some pieces of fresh cutted shiny metallic-Li (SML) in a transparent bottle with (about 10cm3) of the electrolyte under pilot-test, and close this bottle[1]. Observe these pieces of SML, every day, for about 10days, or more. If these SML remain, still, shiny, then it might be proper to commom use.
However, you might like to go for more[2-5] detailed (pre-test-) studies for this 'new' (not, yet, opened) electrolyte.
1. All treatments inside your good GB.
2. Studies on the Anode/Electrolyte Interfacein Lithium Ion Batteries https://link.springer.com/article/10.1007/s007060170110
3. One-Step Processing of Soft Electrolyte/Metallic Lithium Interface for High-Performance Solid-State Lithium Batteries https://pubs.acs.org/doi/abs/10.1021/acsaem.0c01470
4. Recent advances in anodic interface engineering for solid-state lithium-metal batteries https://pubs.rsc.org/en/content/articlelanding/2020/mh/d0mh00050g#!divAbstract
5. Design Principles of the Anode–Electrolyte Interface for All Solid‐State Lithium Metal Batteries https://onlinelibrary.wiley.com/doi/abs/10.1002/smtd.201900592
Dear Ioannis Samaras
We have also, LipF6 powder, DEC, EC and DMC that have not been use yet after 3 years. How can we prepare LiPF6 solution with high quality?
Dear Nasrin Azad ,
if I were you, then I would prefer to buy a new one, e.g. a new fresh, commercial electrolyte, under these (your) conditions.
There is an old rule among chemists - if in doubt about a reagent, then immediatelly throw it away (dispose it, etc.). The cost of research error is higher than the cost of a new reagent, and as a rule, the researcher realizes that he has done unnecessary / erroneous work only after a few months of hard work. At the same time, old reagents can be used for debugging the methodology (e.g. checking cells for leaks), some irresponsible applications, etc. You have to be especially watchful with the students, some are careful initially (many thanks to their mom, dad and all their relatives), others learn quickly, but some behave according to the principle "Après moi le déluge".
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