Intro: Create a Rechargable 2 Volt Aluminum/Titanium Ion Battery
See safety notes below. This is not a build for the timid. Only build in a well ventilated area.
After several years of various experiments, I came upon a workable battery chemistry that is light, safer than Lead-Acid, and easy to make. My original intention was to create a battery that could be manufactured in low-tech environments with limited supplies, and I think I came very close to that ideal with this battery.
After searching the google patent database, I do not believe this idea to be patented. I decided that I could not ever stand to fight the big companies in court if anyone tried to challenge a patent on the material, and I couldn't defend the patent either - as that requires lots of legal representation and great expense. So, in the interest of having my little battery get in the hands of people who need it most - I decided to open source it. I decided to completely share how I built this little guy, and replicate it here with a fresh cell - proving that the technology works.
Composition: Aluminum/AlCl + Hcl + TiO2 + MgO2 + Graphite + Urea (+ mineral oil)
Voltage: 2.10v OCV, the body of work from 2.05v down to 1.80v very similar to lead acid
My current battery appears to still be conditioning, and seems to hold slightly higher voltages for longer each day. I don't know the eventual lifespan or final voltage of this battery, so this is still an unknown. But the behavior seems to reinforce a 2.1v resting voltage, which might eventually be as high as 2.25v.
NOTE: Danger. Be cautious, and wear protective eye wear and disposable gloves. While the battery is ultimately composed of chemicals that are far less nasty than Lead, they are still dangerous. Hydrochloric Acid can burn you, your children, pets, your clothing, the desk - just about anything around you.
Chlorine/Oxygen Gas Hazard: Charging this battery can cause a release of oxygen, which can cause fires. Over charging this battery can cause the release of Chlorine Gas (Cl2) which is nasty stuff. Only build in a well ventilated space, and do not leave an unattended battery charging.
Environmental Note: Do not dump out your battery outside or in the sink. Dispose of battery solutions at your local Hazardous materials collection times. Again, this battery is far less nasty than many, but there's no reason to pollute your local watershed. Be a good steward.
Step 1: Why an Open Source Battery?
Why open source it?
Nickel-Iron batteries are very popular for solar projects. They were patented by Thomas Edison and Co around 1900. They hold a 1.2v charge, were nearly indestructible, able to be deep discharged and overcharged, and have lifespans in the range of 50-100 years. Drawbacks included a high rate of self discharge, weight, and electrolyte maintenance. The first electric cars at the time ran on these 1.2v batteries, and both fell out of favor with the introduction of internal combustion engines. Today, thanks to a resurgence in offgrid/microgrid ideas, these batteries are back in favor - being manufactured here in the US and in China. They are expensive, and made of plastic instead of all steel - and I doubt their 50 year lifespan.. but that aside, what's the interesting thing here? No patent. Who cares, people will buy them and the big companies don't care about appealing to offgrid types. Once I had a good long think about it, I didn't really see the need for a patent for a battery like this. I couldn't defend a patent in court against a mega-corporation if they wanted to steal the idea anyway, they'd bleed me dry in no time. The patent system as it exists today isn't for the small inventor, it's for corporations to wage battle against each other and maintain their competitive edge. This battery isn't super efficient, it's cheap, simple, lightweight and relatively benign. Which makes it perfect for someone in the middle of no-where to use to keep a light on.
I'm a software developer, and have been for nearly 20 years. I developed software for primarily windows-based systems for the first 8 or 10 or so, and then progressed into primarily web-based projects for the rest. Open source software has allowed me to focus on building the solution on powerful software stacks without having to worry about piracy, or licenses, or running out of money before the project even starts because we need the latest versions of the entire OS stack. Go find a community with similar needs and an existing stack, and start building. Give back to the community, and build open products and solutions for others to use. So, this is me giving back.
So go, build batteries, and make the world a better place. This is my gift to you.
This instructable is meant to be the springboard for other experimenters who might wish to help the community develop this battery, share in the general knowledge in its construction, and make the world a better place. My only request is that you share your construction techniques with the community the way I'm sharing now. Open source, but hardware/chemistry.
Step 2: Components: Graphite, Titanium Dioxide, Mangesium Oxide, HCl, Aluminum Chloride, and Urea
The original battery was a solution of AlCl, water, Hcl, aluminum, and graphite. It worked, but suffered greatly from self-discharge, in a matter of minutes. It showed promise, but went away too quickly. After much experimentation, I discovered the TiO2 and MgO gave the battery a "depth" of charge, likely due to electrodeposition of the metals within the electrolyte... more later in the "Theory of Operation" section.
Graphite - fancy or simple, graphite is graphite. My base cell actually used a block shaped piece of artists graphite, you could use whatever - even mechanical pencil leads... all the way to expensive graphite blocks or activated carbon blocks. Carbon is your friend.
Powdered Titanium Dioxide is used in white paint, food coloring, and all kinds of household products. It is, as far as most uses around the house are concerned, inert. I sourced mine from a pottery supply company online. You could easily find it in large bags from cake or soapmaking suppliers. Versatile stuff.
Magnesium Oxide is used as an antacid, becoming Magnesium Hydroxide when mixed with water. It is somewhat caustic.
Our goal is to combine these with HCl, and facilitate their reaction into TiCl and MgCl and have them play with the AlCl as our electrolyte. I'm not sure this actually happens in the base cell until we have a Deep Eutectic Solvent (more later) formed with the urea.
Aluminum Chloride is kind of nasty. Wear gloves. I did not purchase mine, but made it by dissolving Aluminum foil in diluted HCl. The next step will detail how I did this, and why it was stupid to do it indoors. If you purchase AlCl anhydrous, know that you must be very careful not to spill it, and to wear a mask - it's very bad for your lungs.
Water: Any extra water will eventually have to be electrolyzed out before the battery will come to full potential. some water is necessary to slow down the AlCl reaction if you make it yourself... so it just takes longer to condition the battery.
Hydrochloric Acid is nasty stuff. Be careful with it. I purchased 200 plastic eye droppers to measure and dispense. It reacts with water in the air, in your nose, your throat and lungs. Ventilation is your friend. I purchased the acid at my local hardware store, generally used for cleaning brick or concrete as "Muriatic Acid"
Urea is a main component of urine. I did not use urine. I used a spreadable "de-icer" that is composed mostly of urea. Also, it has a pretty blue color. Some gardening centers may also sell urea as fertilizer. This is the hydrogen bond donator for our DES. This was a later addition in my original working battery, but I'm going to add it upfront when making the electrolyte for this one. Gloves are probably a good idea.
Borax (Sodium Tetra Borate) is a water softener that can be purchased in your laundry aisle, it also works as a flux in soldering, and seems to assist the power retention and output capabilities of the battery.
AGAIN: Most sidewalk salt is just salt, KCl or NaCl - these are not substitutes for the urea. If you can't find this stuff (say in a warm climate), look in a garden center for a urea fertilizer. You could always make it yourself, but thats a whole other instructible involving urine.
Gloves: Heck, just wear gloves all the time - you can buy a box of 50 for a few dollars.
Step 3: Safety
I'm American, so I feel compelled to tell you about safety... especially with the possibility of our younger viewers messing with this stuff (Only attempt with a responsible sober adult nearby, hopefully YOU are the responsible sober adult). I'm leaving the actual implementation of safety to the reader, but here are some strong suggestions: In short: "Keep it off your skin, and out of your eyes and mouth. Keep pets and small children at a distance"
Gloves - Nitrile will permeate 37% Hydrochloric acid in about 15 minutes ( source: Kimberly Clarke ), once diluted to 10% you're completely safe. If using Nitrile, change gloves immediately following at any step where Hcl is exposed to the air as it can create a "cloud" of hcl particles in damp air. Latex appears to be *slightly* better ( source ) Neoprene and rubber appear to be the best for hcl ( source )
Dust Mask - While something rebust is probably a good idea, I just use a fine dust mask. I have a bunch of these from my basement mortar repointing.
Face shield - I use a full grinding shield when possible. Again, a left-over from my repointing work.
Clothing Covering "Lab Coat" - I use a chef coat, because it buttons across the top of my shirt. And nothing says mad science like a chef coat.
Nearby Shower - acid burns skin badly.. a nearby shower is a good thing.
Big Box of Baking Soda - Arm and Hammer. Baking soda will nuetralize acid while you run for the shower. It will also neutralize spills... eventually. Keep pouring it on and rinsing off until you stop feeling like a clumsy fool. I can tell you that it takes more soda and water than you think, and the pain will endure even after you're completely rinsed.
Be Safe! Slow and Steady wins the race.
Step 4: Graphite/Carbon
Our cathode(+) is made of graphite for various reasons. In an acidic solution, you're going to corrode the living crud out of anything you use as the positive terminal. It's going to literally fly apart. But graphite is different, it really likes to stay put. I've considered Manganese Dioxide for a positive electrode, but I'm not sure it will "stay put", I'll leave that experiment to someone else.
Because we "eventually" convert all the Hcl to various chlorides, it is possible that an aluminum or other cathode (+), but that would require some additional experimentation. copper, iron, manganese dioxide are all good candidates.
I'm using pyrolytic graphite, specifically scrap from glassmaking. I'm going to be trying "graphite gasket" material eventually as well.
Powdered graphite? I haven't tried it, but I don't see why not. Getting it to stay put is probably the challenge, or compressing it into a block, or mix with JUST enough epoxy to hold it together.
Carbon Fiber/other forms of carbon: In some early experiments, non-graphite carbon flakes off into tiny bits of black evil stuff that cloud the electrolyte, and possibly cause the battery to stop working. it wasn't exactly a success. Perhaps a "conditioned battery" could have a carbon fiber or sheet added, so the charging isn't outgassing a destroying the electrode.
the JBWeld here is also an experiment. I've used gorilla glue and silicone to protect my metal leads, and it worked well - but I wanted to see if something stronger would work. if you leave your metal leads exposed, they will corrode. If they are made of steel, you also risk releasing chromate, which is nasty stuff.
NOTE: I'm not sure if the JB Weld failed, but the bubbling of the electrolyte completely dissolved the steel wire in just a few hours - I replaced with a graphite stick. I do not know the status of the epoxy, as it is still in the battery. I had no idea it would corrode so quickly.
Step 5: [Optional] Making Your Own Aluminum Chloride [Caution]
This process works well when you take your time. Throwing aluminum and HCl in a jar makes clouds of vaporized Hcl, which is not good for your lungs, your lab table, and takes a long time to dissipate. Slow and steady.
Try this outside before moving it indoors. I made the initial mistake of doing it indoors the first time, and it took quite a while to vent my lab.
I made my original AlCl over the course of several weeks, 1 Cup of water in a pyrex container (or Ball canning jar), 5mL of HCl, and lots of little strips of Aluminum. Drop then in the water and they will slowly dissolve, giving off hydrogen gas. Drop one in, and let it go slowly over the next few days until it is gone. as time goes by you can add more HCl, or more aluminum until you have a fairly concentrated mix.
Do not seal the jar. Put a lid on it, you don't want cats drinking it, or it to spill ... but make sure the lid is only just barely touching, so the hydrogen doesn't build up. Test it every few days (with gloves on), loosen the lid to see if it outgasses. Also, keep the jar away from flames and ignition sources (sparks), hydrogen is able to explode at very low and very high concentrations
Slow and steady, take your time.
Or just buy it online. This instructable is not adding AlCl, I'm going to see if the additional step is even necessary if the TiCl4, MgCl, and urea might be enough. If it isn't, I'll fix the instructable.
Step 6: Making the Electrolyte (Deep Eutectic Solvent)
Step 1: Create the chlorides
Step 2: Add Urea
Step 3: Gently heat until Deep Eutectic Solvent forms (the salts and urea will stay liquid at room temp)
In this experiment I used about 1/4c of TiO2 (~ 100ml), and 1 Tbl MgO (~15mL) Normally I would have mixed the Aluminum powder into the mix at this time as well, but I want to see if the TiO2 and MgO will convert alone, or if the AlCl is actually needed. I'm using Aluminum screen for my anode(-), and I want to see how it reacts in the paste, or if the addition of AlCl keeps the anode(-) from being dissolved by the acid.
I started adding HCl (5ml at a time), but realized that the TiCl wants to react with the humidity in the air to make a toxic vapor. So, I added 100ml of bottled water instead, then proceeded with 4 x 5mL droppers of Hcl into the jar. The powders formed a thick paste. I closed the jar (loosely) to allow the reaction to proceed. The jar became warm. I left the jar for 24 hours.
I added 1/8 cup (~50mL) of urea granules (SafeTPet), and heat the mixture in a microwave until it begins to melt. If you use a microwave, know that the urea will start giving off ammonia gas if you leave it too long. Only short pulses. And clean that sucker out before you make popcorn... or get a dedicated "mad science" microwave for your lab. Once I can see the solvent is liquid and mixed with the TiO2, I proceeded to construct the cell.
It only took about 30 seconds in the microwave to have much of the granules dissolve into the paste, which changed consistency from an extremely thick paste to a "watery" pale blue. The jar was extremely hot, be careful. While some of this might just be urea reacting with the Hcl residue, it's our starting point for constructing the battery. In a proper lab, without having to resort to additional water, and just building the battery, it would likely not have the length conditioning step that mine requires to get rid of all the excess water.
TiO2 will convert to TiCl4 in the presence of HCl, but water will cause it to revert back to TiO2 as Hcl. I think the MgO stays as MgCl, and the urea will form Ammonium Chloride, but I've noticed - once the water has left the system (via evaporation or hydrolysis), the resulting solution forms a gel, and no longer electrolyzes - consistent with a DES.
Step 7: Building the Battery
In this experiment, I'm using Aluminum window screen for my anode(-) and also using Tyvek as a membrane between my graphite cathode(+) and the aluminum. The screen tends to have a lot of strays, so I needed something that would prevent a short in the battery.
I'm recycling the tyvek from a used priority mail envelope. Tyvek has microscopic holes that will allow ions to pass if both sides are dry (water vapor), or wet (dissolved ions). Make sure you get some of the electrolyte inside the membrane, or it won't work. I tilted the jar until it ran down inside.
Initial voltage was 1.189v, showing that it was acting as a metal-air battery (Al-Air batteries run around 1.2v) .. so, yes, you could stop here and have a nice rechargable Al-Air battery... but we're gonna condition this bad boy (and probably add more electrolyte to cover the graphite)
Step 8: Mineral Oil
Early on, I surmised that atmospheric Oxygen (or CO2, or humidity) was adversely affecting the battery. I'm not 100% convinced this is the case, but pouring a layer of mineral oil over the completed/conditioned battery seemed to really improve the stability.
This was a trick I stole from the Edison NiFe batteries. He would sell something called "battery oil", which was just mineral oil (baby oil without any scent added), which sealed out the atmosphere, but allowed generated hydrogen or oxygen gasses to bubble out.
The only problem I see, is that you can't really mess with the battery once you add this... you risk your electrodes getting coated in oil and being rendered useless.
So mineral oil is a final step. Once you're satisfied with the construction, you add the oil. Conditioning, charge and discharge will proceed as normal after the oil is added.
Step 9: Conditioning the Battery
I tried charging my initial battery at 3v for a few weeks, and it didn't seem to get anywhere. Then, fed up, I left it at 12v all day - and it suddenly improved. After a good 12v charge, I could do slower 3v change/discharges and get a lot more power out of the thing. Also, this was when I noticed that it stopped bubbling, or only bubbled occasional small single bubbles. These are oxygen from the Titanium (or magnesium, or aluminum) Oxides being electrolyzed. A slow charge doesn't seem to make much of these.
So, it takes a while to get most of the water out of the mix. This can be done fast or slow, but you're going to have to expend a lot of energy doing it. Having pure Chlorides to start with would change this. For now, it's a reality.
So, Conditioning: Run it up (3-12v until it stabilizes), run it down to something like 1.5v - repeat. At first you kind of have to run it down lower (0.9v to 1v) to get it set up for better charges later. In general, 3v for 8 hours @ 1 amp will charge it nicely.
I have no idea how many cycles it takes to get it right. My little version of this one seems to still be improving, and it's probably upwards of 100 cycles right now.
I may try a standard NiMH charger and see what happens.
I still do not know the best voltage. -1.63v is the voltage to deposit aluminum, -1.67v for titanium, -2.37v for magnesium. which give us ~3.34v for titanium ~3.26v for aluminum and 4.74v for magnesium. I wouldn't hold my breath on electrodepositing magnesium. BUT, a 3.34v@1amp charge takes a long time. I suppose I should invest in a power supply that can push 3 or 4 amps at that voltage.
Honestly, this step is probably the thing I could use the most help on. Any ideas are appreciated.
UPDATE (9/9/15): If it doesn't want to condition, or doesn't hold power - try reversing the voltage -12v or so for 10 minutes, followed by long 3.5v charge - there seems to be a passivation layer that can build up that must be overcome. This might be something to do in general long-term maintenance as well.
NOTE: Water will electrolyze at our charge voltages (which are somewhere in the neighborhood of 2.5 - 3.11v), Chlorine will start bubbling out if you run the battery at too high of a voltage. If you smell any Chlorine in the room, turn the voltage down until you find the sweet spot. Also, a Well Ventilated Room.
Voltage on the cell *seems* to want to hang out at 2.5v, which is our theoretical sweet spot - but Most of my experiments seem to settle over several hours to around 2.1v, hanging out for a long time around 2.0v .. discharge seems to really happen between 2.0v and 1.8v.
Step 10: Charge/Discharge Curves and What I Don't Know
My initial experiment used a graphite/clay artist's graphite, rolled/cut aluminum foil, with maybe the surface area of a button cell battery in the electrolyte. This could hold around 2.5v->2.0v for 24-48 hours, slowly self-discharging. For my purposes (holding power from solar panels to be used right away at night) this met my criteria as useful... I don't need batteries sitting charged for a month, generate/store/use within 24 hours.
To this end, I can do an 8 hour charge with that small cell 3v@1amp , and then light a 1.7v red LED and 1k resistor for about 5 or 6 hours... not exactly good, but that's part of the reason I'm building this bigger one.. I can charge a battery, and light an LED.
That's about all I can tell you at the moment, I'll be building an arduino-based "conditioner" circuit, as well as try to have this cell be charge/discharged in daily cycles using a solar panel to see how it improves in real conditions.
Step 11: Lessons Learned on This Build
1. JBWeld on steel will not protect the cathode(+).. it will corrode in a matter of days.. the weld may survive as a epoxy, but steel will dissolve.
2. Where the anode(-) reaches the air (or oil) will also corrode.. it took mine about a week. The aluminum screen down in the solution seems fine, but at the transition layer it corroded away. This is likely due to chlorine evolving and rising through the liquid and sitting at the transition. having graphite as the final "leg" on both electrodes will probably make the whole system work better.
3. The anode definitely affects the final voltage, as does the ratios of Urea/Hcl/Metal Chlorides ... In balance, the anode does not seem to corrode, as the urea or other reduced metals scoop up the hydrogen/chlorine to protect the anode... at the moment, I think this relies on a surplus of urea, but I'm not yet sure.
4. Sudden drop in performance? Either reverse charge it briefly (explained earlier) or your anode(-) has dissolved because you have excess HCl floating around. Just insert a new anode(-) and you're back in action. Eventually the AlCl/TiO2 comes into a balance where you're not losing any more Aluminum to free Hcl.
5. Borax helps my more Iron-based version, so you might want to mix Borax in when making your cell.
Step 12: Recycling
Ok. so, AlCL (and TiCL/MgCl) are moderately nasty stuff, how do I recycle it?
The general idea is to convert them back into the oxides, or hydroxides that you started with.
Step 1: Dilute the soluble parts of the battery with water (slowly)
Step 2: Slowly/Carefully add a solution of NaOH (Sodium Hydroxide) or KOH (Potassium Hydroxide). This will convert the chlorides to hydroxides, which can then be recycled as normal, melted down (in the case of AlOH), whatever. Some hydrogen may be released from the solution.
This step will need to be expanded. Ultimately, I'd like to show how to completely convert the AlOH back to aluminum for a closed loop, but that will probably take a whole lot more energy that we want - for now, we'll settle for "least nasty form"