Here are the steps I currently use to prepare sodium foils for half-cell sodium-ion batteries in the glovebox:
1) I first dry sodium metal cubes (stored in mineral oils) with filter paper and then cut the cubes into thin slices with a knife
2) I briefly wash the slices in hexane solution to further remove mineral oil
3) I sandwich the slices in between two plastic films and roll press them into thinner slices
4) Again, I cut the thinner slices into desirable sizes and store them in clean hexane solution for future use.
I have prepared many sodium foils this way, but the chance of getting a perfectly smooth foil is close to none, and the foils often show some yellowish stains after just a few days in the hexane solution (I had to scrap off the stains prior to using these foils).
So I am wondering if anyone prepares sodium foil differently and has good preparation methods to share with me. Any suggestion will be greatly appreciated.
Please allow me to make a guess:
I think the foil became rough since you slice the sodium cube with a knife. This is especially true when mechanical stability is not sufficient in your slicing setup.
I guess a better way you can do is to make a thin sheet of sodium foil by the electrolysis method.
We had prepared the thin slice just before use, cutting the Na cube within the paraffin oil with a sharp blade to desired thickness, taken it out with a Pt wire pin onto a dry filter paper finally washing the slice with a volatile solvent and dried it under vacuum .
If you want a very (atomically) smooth surface - you would need to melt your sodium, and perhaps use something like the "overflow downdraw method" used for producing glass. I don't know if this is doable in a glovebox (check safety!!!), but Na melts at ~100'C...
A (fluorinated) long alkane should be a better liquid for storing Na, as it expels water much better than hexane. You can, of course, always keep sacrificial Na flakes in that storage container as a getter.
Whatever you do, please check with a knowledgeable chemist before doing any experiment! A fire in a glove box is not something your experiment and your supervisor would enjoy...
Try to use a rolling pin (make of plastic with smooth surface) to smooth your sodium foil, and then cut it into desirable size (I prepared it in this way, and the prepared sodium foils seems suitable for coin cell). In addition, I don't think we need to storage the sodium foil in hexanes (may cause contammination), since we always use them out in several days. If the surface of sodium foil would not as bright as fresh prepared one after several of days storage in the golve box, then we may need to scrape the surface before coin cell assembly.
Our process is:
1) wash off the oil with same solvent as your electrolyte (minimizes contaminations) and dry with filter paper2) cut off the oxidized planes
3) put into a plastic bag, take a pizza roller and shape a foil to your need
All the processes were conducted in Ar fill glove box.
Need: Stainless steel pot, Heating coil, Two piece of Polypropylene block to press the molten Na . Punch
Process:Step:1 Set the temperature of the pot 135 C (Na melt around 97 C) Step 2: then pour the Na rod and it may take 5 to 10 mins (for 0.1g of Na) to get molten Na Step 3: pour the molten Na on polypropylene made block and press with another polypropylene block by hand, foil will be ready then punched the electrode . Be always careful as there will be plenty of flammable stuff inside the glove box.
Thanks,
Nupur
As far I know, we dont get Sodium foil. instead we get sodium ingot or chunk
my procedure is , first cut off the oxidized part and the kept it in a small plastic bag and make it thin by hummer , and cut it with the cutter , all of in the Ar filled glove box.
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