See if You Can Reverse Engineer This Scrap Metal Battery

We got quite a few tips in about a paper from Vanderbilt about a cool scrap metal battery they’ve been playing with. They made some pretty bold claims and when we fed the numbers in they pretty much say they’ve got a battery you can make at home, that can hold half as much as a lead acid, can be made out of scraps in a cave (even if you’re not Tony Stark), charge super fast,and can cycle 5,000 times without appreciable capacity loss.  Needless to say that’s super cool.

Of course, science research is as broken as ever and the paper was hidden behind a paywall. Through mysterious powers such as the library and bothering people we were able to get past this cunning defense and read the paper. Unfortunately the paper reads more like a brag track than a useful experimental guide on how to build the dang battery. It’s also possible that our copy was missing some pages. Anyway, we want to do science!

Anyway, here’s what we know. The battery is based on an ancient battery called the Baghdad Battery. The ancient battery supposedly used iron and copper with a mystery electrolyte. The scrap battery, however, is made from scrap iron and scrap brass. The iron makes sense, but why brass? Well, brass has copper in it, and you can still get at it chemically even if it’s alloyed.

To that end, the next step was to throw some oxygen atoms in with those pesky Fe and Cu ones. The goal is to get a redox reaction going. If you do it right you can achieve pseudocapacitance. To to this the researchers used “common household chemicals and voltages” to anodize the iron and copper inside the brass. The press photo have them holding a gallon of muratic acid, if that helps. We don’t know, but if they can jam a few oxygen atoms in there then so can we!

After that it’s all about sitting the electrodes in a bath of potassium hydroxide. We guess you can scrape the inside of an AA for that. Anyway, the paper’s light on process but the battery seems really cool. They’re not pursuing this research for commercialization, instead going the OSHW route. They hope to get to the point where anyone can just grind up a bunch of scrap steel and brass, maybe throw it in a birdcage, anodize it, and get a super long life battery for grid use for less than a lead acid. If any of you manage to build one of these drop us a tip!

 

 

38 thoughts on “See if You Can Reverse Engineer This Scrap Metal Battery

  1. This is like in Skyrim when you enter a cave and you see fresh fruit, glass jars and bottles of muriatic acid, right?

    Made in a cave but only if you bring everything else with you.

  2. I’m having difficulty understanding how they maintain the anodic film while drawing current from this system. To the extent one can anodize (certain) steels the process is done in KOH baths. Commercially this is done for decorative purposes on stainless, but the coating is very thin and not durable at all. Something is missing here.

  3. Basically what I have been working on the past few months, Fe2O3 anodes with NiOH, NiOOH and MnO2 cathodes psuedocapacitance or faradaic redox reactions on anode and cathode. CuOH also works as a cathode this has been all over the place if anyone has been researching. Transition metal oxides are key to high energy density.

    Electrolyte is usually basic, 6M KOH seems to work really well but cycle life is poor. Some other papers are calling for using 1M KOH and 0.5 M NaSO4 and getting better results. Largest energy density’s being reported are at over 90mAh per gram with 1.6volts potential (decreasing linearly like a supercapacitor)

    The problem with their psuedo-battery/capacitor is surface area, and thus power density, which I have pretty much solved in a cheap facile synthesis. I am working on a video that will try to satisfy all the hating naysayers and hopefully satisfy the “you can’t do this properly because you have no resources crowd.”

    1. > The problem with their psuedo-battery/capacitor is surface area
      What about creating a foam from the metals using an active foaming agent (Maybe bicarbonate?) or inactive foaming agent like rock salt followed by a water bath?

      1. Yes, that is what alot of papers are doing starting with a nickel foam and then growing MnO2 and NiOH nanocrystals on them using a 0.1 M potassium permanganate bath. Problematically creating metal foams is very energy intensive.

        There is a better solution, in my opinion, to getting low cost high surface area transition metal oxides attached to a conductive backbone. Here is a clue, slightly related to my methods, they even mention using these carbon sheets prepared form t-shirts as an electrode. http://pubs.rsc.org/en/Content/ArticlePDF/2016/RA/c5ra19616g

    2. I’m sure it’s not what you’re doing, as you said you’re working with Ni/Mn rather than Cu, but if I were to start from the paper’s combination of solid steel and solid yellow brass, and try to improve surface area, I’d be inclined to experiment with steel wool for the anode and bronze wool for the cathode. (I have no idea what alloy of bronze is used for bronze wool — it should have plenty of Cu, but could have other elements that would keep it from working.)

      Though I wonder if that might be too fine? Even #4 steel wool (the coarsest I know of) has only .005″ average fiber width; I wonder if the resistance in each strand may be too high — a 3″ length would be about 1 ohm. Then again, the ESR for their scrap-metal battery was 6.23 ohm, and you have a gazillion strand resistances in parallel — whether or not you can get down to ESR values comparable to a commercial supercapacitor or Li-ion cell, you should be able to improve on the scrap-metal version.

      1. That sounds like a great idea and should be incredibly less complicated, but use far more metal compared to what I am doing. Although surface area really wont be that much more impressive, your idea however would allow actual useful batteries. Keep in mind their calculation for 20mAh per gram was solely accounting for the oxides not the base metal beneath the active part.

        Why not just use copper wool for the cathode? (I could not locate nickel wool)

        Considering you get new clean wools, I would not bother with the HCL washing step.

        Keep in mind ESR also factors in reaction kinematics and the electrolyte conductivity among other things so the thickness of the oxide layer can increase this number.

        Really good idea I look forward to seeing it on the front page and on HAD.io

        1. I missed that about only counting the active layer. It seemed too good to be true; so that’s what I was missing.

          Never heard of copper wool till you mentioned it, but yeah, sounds great.

          I’m not going to pursue it — capacitors/batteries aren’t my thing, and I’ve got enough projects going as is. But I’d certainly love to see somebody else run with it and put it up on HAD.io so I can hear how it worked out.

          As in, I came up with the idea — somebody else do all the work, and we’ll split the profits! ;-)

  4. The paper makes a misleading claim r.e. the abundance of Cu vs Ni, there is more Cu in circulation but Ni is more abundant on Earth. They talk of fast cycling, as if that matters in a household power scenario, it doesn’t as a domestic power cycle is typically diurnal. What can matter is peak power during the startup of motors driving heat-pumps etc. but this is easily managed with capacitors &or smarter motor controls.

    They mention a resistance of 6.23Ω per cell, so what is the realistic estimate of the internal resistance for a 25v battery?

    The paper is an interesting read, however I’m not convinced that it is significant work because the sol-gel process will allow you to assemble cells where the structure and conductors are carbon based and the active surfaces use minimal amounts of valuable elements. I also suspect that they did not examine the economics of copper deeply enough and have overlooked the nature of it’s long term demand curve compared with other elements of similar or greater abundance.

    One also has to wonder when was the last time that they put out a bin of domestic waste for recycling and actually examined the contents, because from my observations the metals are iron, aluminium and traces of tin, and almost never copper or brass.

    Anyway it is still worth a read even if it is just for their list of references, so enjoy:

    https://chart.googleapis.com/chart?chs=350×350&cht=qr&chl=http%3A%2F%2Fgen.lib.rus.ec%2Fscimag%2Findex.php%3Fs%3D10.1002%2Fadfm.201102796&choe=UTF-8

  5. Wow, when just a little information is released the signal to noise ratio is really low.
    One hopeful quote from the “www.vanderbuilt.edu” site is ““We’re forging new ground with this project, where a positive outcome is not commercialization, but instead a clear set of instructions that can be addressed to the general public…”
    Menchanix posted a paper that used anodized aluminum and the Hummer method to produce Graphene in the spaces created by the anodization process. Totally confused by disparate information. But one clarification that needs to be made is “is this a battery or a capacitor?”
    Rather than waste brain-cycle time on such scant information I will anxiously wait for more information out of Vanderbilt.

    1. “But one clarification that needs to be made is ‘is this a battery or a capacitor?'”
      There’s no clarification to be made — the confusion arises from varying definitions of “battery”, not from not knowing what sort of device this is.

      It’s a metal-oxide type supercapacitor. There’s some debate as to where to draw the supercapacitor/battery line — these devices are more battery-like than Li-ion supercapacitors, which are in turn more battery-like than carbon-type supercapacitors. Whether that makes it a “battery” or just “the very most battery-like capacitor imaginable” is all down to how you define battery.

    2. The curves for current and volts when it charges and discharges will tell you if it is either or both of those. An electrochemical cell can have significant capacitance if the electrode area is large, but can a capacitor be made using a redox reaction? No it can’t because then it is an electrochemical cell, so a hybrid is always a “battery”. It is a matter of electrostatic vs electrochemical potential.

      1. You are correct for the most part, however pseudocapacitance usually accounts for 200x the energy storage even in an edlc with a redox active electrolyte or a redox cathode. The psuedocapacitance is couple with the double layer in pretty much every explanation I have heard.

        When using aqueous electrolytes it’s all much grayer than black and white, and is still a huge subject of debate even within those communities that understand these things. ( I assume you do)

        Even then people would scream semantics over calling a single cell a battery. To me it’s more of a smear from strict capacitance(permittivity) to double layer to surface redox to intercalation redox to whole colloid redox to bulk redox.

        I guess I am agreeing with you, I don’t know this all makes me feel like an idiot from time to time.

        However an aqueous LiMn2O4 cell would greatly disagree with your theory to look at the curves, the CV curve looks supercapacitor like yet the energy density suggests other wise 120mAh per gram. I don’t know what I am talking about.

        1. Hmmm yes, perhaps we should coin a new term, the “fabulous capacitor”, and as for the term battery, well I’d much prefer that than run the risk of accidentally visualising Benjamin Franklin’s piles.

    1. As a non-chemist, if they want to have Oxygen in the electrolyte the trick is to add a few mL of Hydrogen Peroxide to the Muriatic acid. When you etch PCBs or strip gold off circuit boards adding oxygen that way speeds up the process 50 times. A fish tank bubbler also works, but uses power which equals lower energy density when you are talking batteries.

      Years ago (1984) I came across a far better non rechargeable scrap metal battery: An Aluminium-air fuel cell. A fish tank with a KOH electrolyte. Submerged in this is scrap Aluminium making up the cathode of the battery. The Air anode was made by carbon black infused paper bonded by a polymer in the side of the fishtank having Oxygen from the surrounding air on one side and the electrolyte on the other. This battery had a energy density of 4KWh /Kg of Aluminium. Aluminium is abundant, brass and copper is not and is worth more as scrap-metal than the lead acid battery it substitutes.

      A little more on the Al-air fuel cell: The electrolyte was circulated by a small pump to dislodge buildup of reaction products on the aluminium cathode. Current capability was not that high 400mA per 100 cm2 of aluminium. The prototype had multiple parallel fins under a pc fan to maximize surface area exposed to the air, the 4 Kg prototype battery had 10 Kwh capacity and each cell was series connected to produce 12V. It never went into production but according to Youtube, a lot of hackers are making AL-air fuel cells.

      In my opinion, this makes a much better and cheaper battery than the above mentioned.

      1. Aluminum ores are meant to be practically everywhere…

        I read about these Al batteries producing about as much energy as is “embodied” in the Aluminum.

        Copious amounts of power, hydroelectric, wind, geothermal, tidal, etc etc, are available great distances from urban centers.

        Ergo, why not site power plants in the middle of nowhere that make aluminum in suitable form for batteries and carry it out by most economical method like a solar or wind powered ship.

  6. As far as I understood the paper, this should be the “receipt” using “household items and chemicals”:
    1. Take carbon steel (1010 steel) and brass (“Yellow brass”, 67% CU, 33% Zn), cut it in small squares
    2. Ultrasonic-clean the metal in an aceton bath for 10 min
    3. Ultrasonic-clean the metal in an ethanol/water bath for 10 min
    4. Anodize the steel at 40V for 900 seconds in 0.05M NH4F in 3 vol% of water with ethylene glycol.
    4a for 0.05M Nh4F (ammonium fluoride) just buy 40% solution and mix 4,6mL solution with 1L of water)
    4b As far as I understood the paper, the anodization is done with steel as the anode and Pt-foil as the cathode (household! ha!) [cit.: “The counter electrode and the reference electrode in these set ups were a Pt foil and saturated calomel electrode respectively”]
    4c They claim that nanorods will grow on the steel (I researched that; this is indeed a broadly used method to grow nanorods)
    5. Wash the steel and dry it in air.
    6. Anneal the steel (they used 350°C for 1 hour under Ar(1SLM)/H2 (200 sccm) flow (household! Ha!)
    7. Remove the oxide on the brass with 5 mL 37% HCl / 10mL (ultrapure -> household! Ha!) water solution
    8. Anodize the brass with KOH (2M solution; -> take 55mL pure KOH on 1L of water) “using 100 cyclic voltammetric sweeps between 0 V and 0.6 V” -> for how long?!
    8a maybe this is can easily been done with some kind of microcontroller
    8b As far as I understood the paper, the anodization is done with brass as the anode and Pt-foil for the cathode
    8c (they claim to also have anodized the brass galvanostatically “using a current density of 1 mA/cm2 for 300 seconds”)
    8d The goal is to grow “copper oxide nanothorns” on the brass
    9 build (a) cell(s) with the (anodized) steel electrode as anode and the (anodized) brass electrode as cathode. As electrolyte use 1M KOH (27,5mL KOH on 1L of water; or 110mL on 4L)
    10 now you should have a working battery

    So in reality you need much more than the claimed ingredients, but none of all chemicals or materials are unobtainium. So I should try this out I guess.
    Maybe the receipt can be refined with some actual scavanged parts or actual household-chemicals? How could annealing be done at home without the gas?
    How could you substitute the ultrasonic cleaning? Any househould-source for Nh4F?

    1. For inert gas:
      I’d guess at this temperature Nitrogen will be inert enough for annealing. Make a N2 generator from nitrite and ammonia, use a packed bed wet scrubber to remove the ammonia and nitrogen oxides and Voilà, stream of inert gas.
      CO2 might be inert enough, though I’d fear carbonate formation ruining your nanorods

      For Nh4F
      Get a source of fluoride from a place that works with water treatment and do a double displacement with some ammonium salt?

      No idea about ultrasonic cleaning, sry.
      And since I have a more or less equipped inorganic chem lab at my garage I may as well give it a shot. Someone should create a project on hackaday.io…

      1. The Argon is easy to obtain at the welding store, I don’t know about the H2. Although there are also N2/H2 forming /welding gases of different proportions. Perhaps you could also buy Ar/H2 mixtures.

    2. The ultrasonic cleaning is one of the easier parts. You get sometimes cheap ultrasonic cleaners for ~20$ for CDs, watches or glasses. 37% HCl and distilled water are also not that difficult to get. For just this cleaning step i dont think, that it really has to be ULTRApure. Argon can be bought. But my baking oven does not go up to 350°C And fluorides are quite toxic, I don’t know if I could buy this and if i really WANT to posses this stuff.

  7. There is no need to use heat treatment. If the goal is to stabilize the surface oxide, it is possible to leave it baking in the sun for few days. A quick laboratory fix is to use argon and the high temperature. Iron in (Steel) can also be anodized in NaOH instead. There are many ways to reverse engineer this battery. The important thing is the pairing of iron oxide (anode) in steel and copper oxide (cathode) in brass. If we use nickel instead of brass it becomes the Ni Fe battery but Nickel is expensive so to make a scrap metal battery we need to use cheap scraps.

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