Ibpointless2 Crystal Cells

[Peanutbutter29]

@phi, great job with all the testing and I know it can be boring at times for sure.  I wonder if you could try a couple other variations and have more luck...
To maybe help here specifically, though hopefully not too off with mode of action / reasoning.
We know that Plaster can work for a separator, as it was in the first dry cells.  If we were to then, consider durhams as a separator; we need to add an electrolyte and possibly a conductivity increasing substance to make a full cell.  Of course with 2 metals.

For the electrolyte, Mg, being more reactive than AL won't "provide" amps to a cell.  As pointed out though, what fluid or crystalline Epsom that is touching the Al electrode;  will reduce to AlSO4 and create some potential for work (e.g. charging).  However, the amount touching the Al is low as well as the efficiency of conversion for the charge / discharge cycle. 
One idea would be to move down (less) in reactivity for the electrolyte relative to the Al to increase output.  You could use AlSO4 (as shown) and this would only react upon connection or operation.  You could also move to MnSO4 or ZnSO4 and each would offer more current.  These would all be acidic Hydrate salts.
You could also move up (more) reactive, if you move a larger step to KSO4 or something;  This direction, if reactive, can increase Volts as well (adding from electrolyte). 
Another method would be to go on the alkaline side using one of the Hydroxides.  Most of those are considered fairly reactive;  the lower alkalines being Sodium Carbonate and Borax.  In order for an alkaline to react with a metal it must be Amphoteric, so Iron would be out.  Hydroxides, though; don't provide H20 in a reaction like hydrate salts. 

For conductivity, most salts / electrolytes are conductive to begin with.  Most battery designs since 1890 have used powdered carbon for conductivity enhancement.  Early on, they used graphite and modern cells use acetylene black which is super porous.  Carbon also is used with modern cells to retain moisture and allow off-gassing. 
  Activated carbon is about the easiest for us to get a hold of, being more porous than graphite.  There are many "grades" (I KNOW carbon from earlier marine store) of activity.  The higher the "grade" the more pores and smaller size of the pores.  A quick way to tell activity grade is the "bubble test".  All carbons' off-gas CO2 when first put into water;  this is the water filling the cavities and mixing with ultra fine powders.  The better the grade, the more and longer it will off-gas;  what we used in the store could KILL fish in a small tank if you didn't off-gas first!!!  So, just be sure to pre soak if you use activated.

For moisture regulation, you already have some with the plaster itself (and a reason why it was first used).  Also, all salts by their nature will draw moisture so that can help.  Also, certain salts can be used for their hydrate phase shift temperature.  I found it funny that Zamboni's electrolyte of ZnSO4 has a change at 85 degrees (dropping 2-3 H20).  For him this caused greater confusion of winter to summer changes; but a dry electrolyte of this warmed to 85 would have enough moisture to prolly run, when it had stopped. 
Lastly, the most commonly used moisture regulation in batteries today is Silicon Dioxide; or commonly Silica Gel.  This has been used greatly since the advent of the AGM lead-acid;  where it was first used and still is.  I don't know that you'd need that with the Plaster though.

Oh, I suppose also, just a consideration too for design.  First rule with batteries;  Smaller spacing and larger area (e.g.. less electrolyte volume) equals more current;  however larger spacing (more electrolyte volume) reduces current, but Increases AH life.  So there is a balance there relative to materials. 

Aluminum does offer some challenge (and why its' still a design issue) with it's oxide coating that alters its' potential in these cells.  Unless you have a material to oxidize the oxide, you can't get at Aluminum's full power.  This is also why it shows lower volts than it should for its' place in activity.  E.G. Tin and Al show 150mv in plain water (both have oxide coating barriers). 
If you stay on the acidic side you could move up to Iron.  Zinc would allow a smaller move and amphoterism, so it could be used in acids or bases.  Of course you could as well go down to Mg in some form.  (can find a Mg fire starter stick at wal-mart).  You could check other metals base potentials together in plain water. 

Putting this all together, try a mix of AlSO4, carbon and plaster with your AL for a bit more current while still not "reactive".  Otherwise I might look at a stronger acid or base such as KS04 for acid or Borax for a medium base.  If you used an Iron combo your about limited to ferric sulfate without a lot of reactivity.  If you used Mg then you could do MgSO4 for "non-reactive" or AlSO4 for increased current.  Mg being more reactive I'd stay no higher than borax for the base if used instead, so prolly sodium carbonate or borax. 
  It's a good idea to check the resistance of an completed mix with like non reactive probes, to gain an idea of final current.  Though in modern cells this does vary because of Ion specific separator membranes used;  however you can get an idea and it should be lower for more current.
  For construction, maybe try hardening a cylinder of this mix around one of your carbon rods.   Then you could wrap the perimeter with the Al, Zn, Fe, or Mg.  I think you may have suggested this method to try before?  You could then make this paste layer thinner for more current, or thicker for more AH.  I recommend having a separator still (paper, coffee filter, thin cloth, etc) that can even be penetrated with carbon as a current collector;  this would help extend the life of the electrode, particularly if you use more reactive mixes. 
  Once fully dried, you could do testing as is; but you may find best results by adding moisture to the dried cell.  It will remain moist for a while and should provide you with more, get up and go than you've had so far.  I'd focus testing prolly then on electrolyte ratio relative to moisture levels.  E.g. too much salt and too much moisture are more damaging as you get more reactive.

I hate to see you get discouraged, but I can understand being frustrated.  Maybe some of these things can help?

I suppose too, multiple electrolytes can offer both volts and current in certain combinations;  meaning reaction between electrolytes.  I hesitate to offer these options  as I'd said the chemistry gets complex fast.  I don't want to put anything together that I don't know the reaction of; or know that its' not reactive to start.  Working with Aqua Regia, when I did the mining and scrap stuff;  That will DROP you and take the very breath right out of you!  We used Mil spec masks for dealing with that!  Potassium Permanganate, one of the top 5 most oxidative substances, is used in aquariums as an ORP increasing agent;  that one is a stealthy but strong one.
  It can be a benefit and was first applied to improved Zinc Carbon cells with the addition of Zinc sulfate to the Prior Electrolyte of just Ammonium Chloride.  That Sal Ammoniac was used, because it freely disassociates with Nitrite, Hydrogen and Chloride;  in the batteries.  So it was just to actively provide H and Cl.

Last I put another small video up showing Volts, ma and running of the last MgOH cell and another MgOH cell stack (2).  The one shown the other day still runs fine and gives 1.6v or 1.5 ma Short.  It seems to need 4 drops of water per 32hrs or so.  I show another cell stack around 2.7v and 1.2ma, this is using another gel mix for moisture regulation.  I don't have it sealed to show construction, but we'll see the re-hydration period.  I show the parts for the new cell at the end and even hold the electrolyte mix upside down; so it's not super wet, lol.  Anyway, again the older cell is Mg and MnO2 and the new cell stack is Sn and Mg;  both use MgOH for electrolyte.  These are just testing some variations, so I haven't built them fancy or pretty.
http://www.youtube.com/watch?v=FxM79QzfYfY&feature=youtu.be

Thanks

[PhiChaser]

@phi, great job with all the testing and I know it can be boring at times for sure.  I wonder if you could try a couple other variations and have more luck...
To maybe help here specifically, though hopefully not too off with mode of action / reasoning.
We know that Plaster can work for a separator, as it was in the first dry cells.  If we were to then, consider durhams as a separator; we need to add an electrolyte and possibly a conductivity increasing substance to make a full cell.  Of course with 2 metals.

Thanks and thanks! About where I am at exactly as far as my thinking goes.

For the electrolyte, Mg, being more reactive than AL won't "provide" amps to a cell.  As pointed out though, what fluid or crystalline Epsom that is touching the Al electrode;  will reduce to AlSO4 and create some potential for work (e.g. charging).  However, the amount touching the Al is low as well as the efficiency of conversion for the charge / discharge cycle. 

The reason that changing the amout of epsom won't affect the voltage, gotcha.

One idea would be to move down (less) in reactivity for the electrolyte relative to the Al to increase output.  You could use AlSO4 (as shown) and this would only react upon connection or operation.  You could also move to MnSO4 or ZnSO4 and each would offer more current.  These would all be acidic Hydrate salts.
You could also move up (more) reactive, if you move a larger step to KSO4 or something;  This direction, if reactive, can increase Volts as well (adding from electrolyte). 
Another method would be to go on the alkaline side using one of the Hydroxides.  Most of those are considered fairly reactive;  the lower alkalines being Sodium Carbonate and Borax.  In order for an alkaline to react with a metal it must be Amphoteric, so Iron would be out.  Hydroxides, though; don't provide H20 in a reaction like hydrate salts. 

Whew, Derrick really needs to go to chemistry class... I will have to look up what those are but I can see this is really important. Sodium carbonate and borax, lower alkalines, hydroxides... So borax is a start? Amphoteric, jeeze did you make up that word? j/k

For conductivity, most salts / electrolytes are conductive to begin with.  Most battery designs since 1890 have used powdered carbon for conductivity enhancement.  Early on, they used graphite and modern cells use acetylene black which is super porous.  Carbon also is used with modern cells to retain moisture and allow off-gassing. 
  Activated carbon is about the easiest for us to get a hold of, being more porous than graphite.  There are many "grades" (I KNOW carbon from earlier marine store) of activity.  The higher the "grade" the more pores and smaller size of the pores.  A quick way to tell activity grade is the "bubble test".  All carbons' off-gas CO2 when first put into water;  this is the water filling the cavities and mixing with ultra fine powders.  The better the grade, the more and longer it will off-gas;  what we used in the store could KILL fish in a small tank if you didn't off-gas first!!!  So, just be sure to pre soak if you use activated.

Carbon should be in the mix then... If I use C in the electrolyte it won't mess with the carbon electrode? Outgassing sounds like yet another variable that would have to be controlled.

For moisture regulation, you already have some with the plaster itself (and a reason why it was first used).  Also, all salts by their nature will draw moisture so that can help.  Also, certain salts can be used for their hydrate phase shift temperature.  I found it funny that Zamboni's electrolyte of ZnSO4 has a change at 85 degrees (dropping 2-3 H20).  For him this caused greater confusion of winter to summer changes; but a dry electrolyte of this warmed to 85 would have enough moisture to prolly run, when it had stopped. 
Lastly, the most commonly used moisture regulation in batteries today is Silicon Dioxide; or commonly Silica Gel.  This has been used greatly since the advent of the AGM lead-acid;  where it was first used and still is.  I don't know that you'd need that with the Plaster though.

Oh, I suppose also, just a consideration too for design.  First rule with batteries;  Smaller spacing and larger area (e.g.. less electrolyte volume) equals more current;  however larger spacing (more electrolyte volume) reduces current, but Increases AH life.  So there is a balance there relative to materials. 

So these big clunky cells are not even close to a reasonable size. The 'trodes need to be closer for starters... Silica has been in the back of my head for a while...

Aluminum does offer some challenge (and why its' still a design issue) with it's oxide coating that alters its' potential in these cells.  Unless you have a material to oxidize the oxide, you can't get at Aluminum's full power.  This is also why it shows lower volts than it should for its' place in activity.  E.G. Tin and Al show 150mv in plain water (both have oxide coating barriers). 
If you stay on the acidic side you could move up to Iron.  Zinc would allow a smaller move and amphoterism, so it could be used in acids or bases.  Of course you could as well go down to Mg in some form.  (can find a Mg fire starter stick at wal-mart).  You could check other metals base potentials together in plain water. 

Let me guess, some kind of acid will remove those oxide layers heh heh...

Putting this all together, try a mix of AlSO4, carbon and plaster with your AL for a bit more current while still not "reactive".  Otherwise I might look at a stronger acid or base such as KS04 for acid or Borax for a medium base.  If you used an Iron combo your about limited to ferric sulfate without a lot of reactivity.  If you used Mg then you could do MgSO4 for "non-reactive" or AlSO4 for increased current.  Mg being more reactive I'd stay no higher than borax for the base if used instead, so prolly sodium carbonate or borax. 
  It's a good idea to check the resistance of an completed mix with like non reactive probes, to gain an idea of final current.  Though in modern cells this does vary because of Ion specific separator membranes used;  however you can get an idea and it should be lower for more current.
  For construction, maybe try hardening a cylinder of this mix around one of your carbon rods.   Then you could wrap the perimeter with the Al, Zn, Fe, or Mg.  I think you may have suggested this method to try before?  You could then make this paste layer thinner for more current, or thicker for more AH.  I recommend having a separator still (paper, coffee filter, thin cloth, etc) that can even be penetrated with carbon as a current collector;  this would help extend the life of the electrode, particularly if you use more reactive mixes. 
  Once fully dried, you could do testing as is; but you may find best results by adding moisture to the dried cell.  It will remain moist for a while and should provide you with more, get up and go than you've had so far.  I'd focus testing prolly then on electrolyte ratio relative to moisture levels.  E.g. too much salt and too much moisture are more damaging as you get more reactive.

I was thinking of an Al 'case' that holds the electrolyte. Lots of good info up there; I'm sure I will be re-reading this post again...

I hate to see you get discouraged, but I can understand being frustrated.  Maybe some of these things can help?

You have been a GREAT help PB! Thanks for being patient with your explanations too. Chemistry is it's own animal isn't it? Not like math at all... Not enough for me to 'get it' right away anyways...

I suppose too, multiple electrolytes can offer both volts and current in certain combinations;  meaning reaction between electrolytes.  I hesitate to offer these options  as I'd said the chemistry gets complex fast.  I don't want to put anything together that I don't know the reaction of; or know that its' not reactive to start.  Working with Aqua Regia, when I did the mining and scrap stuff;  That will DROP you and take the very breath right out of you!  We used Mil spec masks for dealing with that!  Potassium Permanganate, one of the top 5 most oxidative substances, is used in aquariums as an ORP increasing agent;  that one is a stealthy but strong one.
  It can be a benefit and was first applied to improved Zinc Carbon cells with the addition of Zinc sulfate to the Prior Electrolyte of just Ammonium Chloride.  That Sal Ammoniac was used, because it freely disassociates with Nitrite, Hydrogen and Chloride;  in the batteries.  So it was just to actively provide H and Cl.

I would like to keep these cells as 'kid friendly' as possible. If all the ingredients are 'grocery store' variety then more people would be likely to duplicate. I don't want to have to wear a gas mask or mix stuff outdoors. Some of those chemistry terms make me nervous heh heh...

Last I put another small video up showing Volts, ma and running of the last MgOH cell and another MgOH cell stack (2).  The one shown the other day still runs fine and gives 1.6v or 1.5 ma Short.  It seems to need 4 drops of water per 32hrs or so.  I show another cell stack around 2.7v and 1.2ma, this is using another gel mix for moisture regulation.  I don't have it sealed to show construction, but we'll see the re-hydration period.  I show the parts for the new cell at the end and even hold the electrolyte mix upside down; so it's not super wet, lol.  Anyway, again the older cell is Mg and MnO2 and the new cell stack is Sn and Mg;  both use MgOH for electrolyte.  These are just testing some variations, so I haven't built them fancy or pretty.
http://www.youtube.com/watch?v=FxM79QzfYfY&feature=youtu.be

I've been thinking that the best electrolyte is likely to be a moist paste huh? Water based would be good...

Thanks

Thanks again to you!

Happy experimenting and keep up the good work,
PC

[PhiChaser]

I made a few cells yesterday; 1:1 mixes with a 1/2 tsp Borax (1/4 tsp per cell) thrown in to see if it makes a difference. So far it looks like the addition may increase voltage (slightly maybe...) and (more hopefully) voltage retention. Too early to tell really, not enough data, but the first cell I charged last night (a few hours on a 6v) tested pretty good. This no longer excites me very much, but this morning the cell that I 'charged' was still reading over two volts that held fairly 'solid' (not falling like a stone when I connected the meter). The VOM sat at over 2.1v which made me smile a little bit. If it is still over two volts tonight when I go to bed it might make me smile more... I think that all the cells I have charged so far haven't held their volts for more than a couple of days. Usually the readings would be lower but it is too early to tell. I haven't tested two of the (4) cells I made yesterday, I may hook one of those to a 6v so I have two charged cells to measure.
Perhaps a new 'ratio' test is in order using a 1:1 ratio of epsom:Durham's and change the amount of Borax?
More to come I'm sure...

Happy experimenting,
PC

[triffid]

My magnesium strip in one cell is broken now.Weakened so much by the tiny amount of oxalic acid from the dandelion leaf that it cant take any handling.LED still glowing bright but afraid to handle it anymore.I'm wondering about creating a complex electrode consisting of aluminum wire screen wrapped around a magnesium strip?With copper as the third metal.Hopefully as the magnesium gets weakened the aluminum screen will maintain electrical connections to the crystal lattice?triffid




At magnesiums higher voltage?

[triffid]

PC,do consider using "bar keepers friend " as a source of oxalic acid for your cells.I will not be using it so you are free to use it if you want.