Author Topic: metallic lithium by electrolysis  (Read 1503 times)

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jimwig

  • Guest
metallic lithium by electrolysis
« on: October 29, 2002, 07:48:00 PM »
metallic lithium by electrolysis -    dammit i forgot the ref details. damm those little batteries.

but its something like Popular Science 1932 or was that 45 anywho by electrolyzing lithium chloride - metallic lithium is obtained,

this is similar i suppose to getting sodium or potassium from molten salts.

i dunno for sho.

Disciple

  • Guest
re:metallic lithium by electrolysis
« Reply #1 on: October 30, 2002, 12:54:00 AM »
from memory you have to melt the desired alkali salt (eg LiCl )with KCl. (These have to be anhydrous i think otherwise it decomposes instead of subliming. A problem is that the working temp of the electrolysis is a fair bit higher than the melting point of LiCl (which is 610 c) .Other cheaper salts such as Li2CO3 can be used . The Li forms on the cathode and chlorine (depending on salt used) is evolved from the anode.
According to a pdf i just found a typical working temp is about 800-900k which i guess is prohibitively high for most bee's but if you've got a jewellers over or sumpin...your set...here's a pdf i just found with some experimental and sample setup pics
http://www.electrochem.org/meetings/past/201/abstracts/abstracts/ag1/1468.PDF

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Polverone

  • Guest
Fused salts not necessary
« Reply #2 on: October 30, 2002, 03:39:00 AM »
Lithium is a special case, compared to the other alkali metals, in that it doesn't need to be formed from molten salts. Lithium chloride in anhydrous pyridine, allyl alcohol, acetone, and various other organic solvents (sorry, don't remember others off the top of my head) can be electrolyzed to yield the metal. I can't find the more comprehensive article that I have around here at the moment, but here's the relevant bit from Louis Kahlenberg's "Note on the Preparation of Metallic Lithium":


I have found that lithium may be obtained in white metallic form from solutions of lithium chloride in pyridine by electrolysis at room temperatures. The method of operation is the simplest possible. It may be described as follows: A concentrated solution of lithium chloride in pyridine is placed in a beaker into which dip a carbon plate (anode) and a brigth iron plate or foil (cathode). Platinum or some other metal may, of course, also serve as cathode, though when used as anode a metal (even platinum) is apt to be attacked and some of its substance carried over to the cathode. No diaphragm is necessary. With a difference of potential of but 14 volts between the electrodes, a current of from 0.2 to 0.3 ampere per 100 sq. cm of cathode area will soon deposit a dense, well-adhering silver white coating of metallic lithium. The deposit thus obtained possesses all the well known physical and chemical properties of the metal.




I recall from my reading of the other article that I can't find right now that acetone works very poorly in comparison with allyl alcohol and pyridine, requiring higher voltage and current and depositing a messy sponge instead of nice shiny metal. I wonder if some of the more common aprotic solvents might be used in place of pyridine.


19th century digital boy

terbium

  • Guest
Solvents
« Reply #3 on: October 30, 2002, 07:01:00 AM »
The Lithium AA batteries are using 1,2-dimethoxyethane and 1,3-dioxolane as solvents. A reason that this type of battery is not rechargeable is only that, as you mentioned, the lithium is plated out in spongy form that would short the battery or otherwise be unsuitable.

Baseline Does Not Exist.

Polverone

  • Guest
More non-aqueous electrochemistry
« Reply #4 on: January 07, 2003, 08:33:00 AM »
I never was able to find the larger article that I recalled reading before. Was it a figment of my imagination? In any case, while searching I found the following:

Electrodeposition of Metals from Non-aqueous Solvents. Chem. Rev.; 1931; 8(2); 335-352.

I would do all the bees a favor and type out the good bits from it, but the good bits in this article are mostly teases because they summarize results but not procedures. The article claims that potassium, sodium, lithium, calcium, and strontium have all been prepared by electrolysis of various of their salts (LiCl, NaSCN, NaI, KSCN, CaCl2, Sr(NO3)2, SrI2) dissolved in acetone.

If anyone can see what Siemens: Z. anorg. Chem. 41, 249 (1904) (or some of the other 44 references in the article) has to say, the details may become clearer. But most of the references are to sources I don't have access to and often couldn't read anyway. I'm sure that a relatively simple and less hazardous way of obtaining some of these metals could be of use to many here. Something to research on a rainy day, maybe...


Rasputin

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"metallic lithium by electrolysis "
« Reply #5 on: June 23, 2003, 01:10:00 AM »
In the book "Chemical Magic" by Sweensy.  The chapter about Lithium gives that exact process as an experiment.  I am going from memory.  He uses a tripod to hold a crucible.  Heating is done with a fisher burner(aprox 1" dia on top)
Lithium chloride and ? are heated to melting.  electrolysis uses anode & cathode (? material) and 2 dry cell batteries to produce elemental Li.



Organikum

  • Guest
nonrecharcheable Li batteries
« Reply #6 on: June 23, 2003, 06:56:00 AM »
arn´t so nonrecharcheable at all as several patents tell.
like

Patent US5493196



This makes me believe that the spongy and messy deposition of the lithium metal in acetone may easily be overcome by using pulsed power similar to the charger described in the patent. Another way is to combine a AC and a DC current. The AC "overlays" the DC. For the LiCl electrolysis in acetone this would say 14V DC and at least 24V AC as overlay.

The necessary currentdensity is for pyridine 0,01 Amp/cm2, for acetone and allylalcohol 0,001 Amp/cm2. (Chemische Technologie 1953)

I say: Diaphragm + acetone + LiCl + pulsed power = easy lithium of high purity.
If I could get LiCl OTC.


sYnThOmAtIc

  • Guest
No???
« Reply #7 on: July 22, 2003, 12:54:00 AM »