Extracting zinc, MnO2 and carbon electrodes from batteries

Abstract:
Many commercial batteries house hidden gems when it comes to their chemical compositions and the Zinc Chloride battery is no exception. I will be attempting the common extraction of a variety of materials, such as manganese(IV) oxide, zinc and carbon electrodes, from these batteries due to their many uses for the amateur chemist who is always looking for OTC resources.

Introduction:
According to their safety sheet, Kodak Zinc chloride batteries contain (by weight):
manganese dioxide 25-30%
zinc 25-30%
carbon 5-10%
zinc chloride >7%
ammonium chloride >7%

Immediately you can see the potential of these batteries, along with most other Zinc Chloride battery brands, with dozens of uses for the chemicals they employ once extracted. Manganese dioxide particularly stands out. With a more correct IUPAC name of manganese(IV) oxide, this metal oxide has a range of uses as a catalyst, an oxidising agent, or as a source of manganese metal along with being great in a thermite mixture. The purity reveals a problem though, as zinc chloride and ammonium chloride is mixed in along with (I have heard) carbon for better conductivity.

The zinc metal also entails a few uses although I only plan to make a few zinc salts as I currently do not have much use for zinc. Although only being contained in a much smaller percentage, the carbon is found mainly as a big, single graphite electrode extremely useful for a multitude of electrolysis reactions. Really only the zinc chloride and ammonium chloride are not worth extracting due to the tiny amount present and the difficulty in doing so in the first place.

The desired materials will be collected and, although the manganese(IV) oxide requires vigorous purification, I will not feature anything past good old water washing as I currently do not need anything other than crude manganese(IV) oxide. Also a bit of scrubbing should be enough for the carbon electrodes and zinc, but if you want a better way to remove the manganese(IV) oxide contamination on them and make them a little more pure or clean, check the last bullet point in the safety section directly below.

Eventually, once I acquire a better source of sulfuric acid, I will attempt a proper purification of manganese(IV) oxide. I am sure you will find that for most insensitive amateur applications crude manganese(IV) oxide should be adequate, for example, as a catalyst for the decomposition of hydrogen peroxide into water and oxygen for the means of acquiring oxygen.

Also I will note that Zinc Chloride batteries and Carbon-Zinc batteries are very similar, having the same main components (manganese(IV) oxide, carbon electrode, zinc). I will only be referring to Kodak Zinc Chloride batteries but various brands of Carbon-Zinc batteries will yield similar components although they may vary in their difficulty to open. Carbon-Zinc Lantern batteries are especially easy to scavenge and also give you much longer carbon electrodes.

Safety:

Substance Hazard information
Carbon Low hazard
Ammonium chloride Harmful
It decomposes on heating to form ammonia gas and hydrogen chloride gas. Warming with alkali will generate ammonia gas.
Manganese(IV) oxide Harmful
Harmful by inhalation or if swallowed. It is often used as a fine powder. Many hazardous reactions occur with reducing agents or concentrated acids.
Zinc Low hazard
Zinc chloride Irritant/Corrosive
Can cause burns and can be harmful if swallowed.
  • Gloves and goggles should always be worn when handling chemicals to protect your sensitive eyes and skin.
  • Work should be carried out in a well ventilated area such as outside or in a fume hood to eliminate the chance of manganese(IV) oxide dust inhalation and the inhalation of fumes given off if the battery is shorted-out or any ammonium chloride decomposes.
  • The work space should be kept clear of any naked flames in the rare case this could lead to the thermal decomposition of ammonium chloride into toxic gases.
  • Manganese(IV) oxide stains everything: hands, plastics, you name it. Although it is not soluble in anything, most reducing agents should do well at removing it. I would recommend applying a solution of sodium bisulfite (or sodium metabisulfite which can be found at brewing stores), but I have heard ascorbic acid and lemon juice – which are a bit easier to get hold of – get the job done as well albeit not as quickly. Or if you missed the gym today and you still want to burn off a few calories, scrubbing with a cloth set aside just for chemical purposes and a little bit of water can somewhat clean things up.

Experimental:
The brand of Zinc Chloride batteries I used (Kodak) was very different to other brands which I had based my method on. I mostly had to use my common sense and knowledge to guess how to take apart the battery as I went.

An open, rimmed, plastic container helped contain the experiment and any contamination. I initially took off the plastic wrapping although this was found to be a bad idea and it was better to leave it on, acting as insulation to help prevent shorting out of the battery until we had removed the carbon electrode.

If the battery does short out, it is wise to leave the battery on the floor (outside where you should be unless you have a fume cupboard) and put a couple of metres between yourself and the battery as it does its shorting-out business and cools off. Better safe than sorry. The battery can heat up burning hot and, although I did not have any of these batteries short out on me, I have experienced other batteries short out while opening them and it is not particularly fun for your fingers. Once the battery has cooled down you should be able to resume taking the battery apart.

I tried to take off the positive steel piece with pliers but it only turned and did not come out. The best way was just to (incoming highly scientific language) cut into the cylindrical bit sticking out of the steel positive terminal piece with the cable cutter part of our pliers and proceeding to grip and tear the steel piece out slowly with the pliers. I had to be careful here to not damage the carbon electrode which is embedded in the cylindrical bit that sticks out of the positive steel piece for obvious reasons. The carbon electrode is the same diameter as the cylindrical bit, conveniently telling you the size of the carbon electrode just by looking at a battery.

Underneath was a thick rubbery piece with a hole where the carbon electrode went through; the gap between the two had a sticky sealer, causing the job of pulling the carbon electrode out with pliers to be very difficult, leading to damage to the carbon electrode. We used a scalpel to cut a circle through the rubbery piece around the carbon electrode and then pulled the cut piece out using the screwdriver. This revealed a second very similar rubbery piece although it was not as thick. It was now possible to pull out the carbon electrode with pliers with a twisting motion. Using the screwdriver we could then remove the remainder of the first rubbery piece and remove the second rubbery piece by the hole where the carbon electrode used to be.

At this point I was just left with the zinc casing, a thin layer of insulating waxy paper, and a black solid – a mixture of manganese dioxide, zinc chloride, ammonium chloride and carbon. The insulating waxy paper covers the insides of the zinc casing, acting as a non-conducting barrier between the black solid and the zinc casing. The black solid can be pulled out with a screwdriver but care needs to be taken to not contaminate it with the insulating paper. The paper can be pulled out and thrown away afterwards. The zinc casing and carbon electrode can be washed and scrubbed with water to remove any black solid and acetone to remove any adhesive contamination. The black solid can be washed with water several times to remove the soluble ammonium chloride and zinc chloride contamination but leave the desired insoluble manganese dioxide slightly purer.

Results:
In total, four Kodak D Zinc Chloride batteries were opened, each taking ~1 hour with the first couple of batteries taking slightly longer as experience was gained. I would not attempt opening anything below D size batteries. If you are feeling particularly patient then maybe minimum C size batteries but definitely nothing below that size unless you just want to get the carbon electrodes and throw away the rest of the battery. This is just because the effort is not justified by the miserable product recovery in these smaller batteries. As NileRed on YouTube says well:

 

“If you had to do this process with AAs or AAAs, I would just really feel bad for you.”

 

Total recovery of crude product:
Manganese(IV) oxide – 110g
Zinc – 80.067g
4 Carbon electrodes (diameter 0.8cm, length 5.7cm) – 21.388g

I have used the manganese(IV) oxide as a catalyst in the decomposition of hydrogen peroxide as a source for oxygen for uses such as mixing with hydrogen to test the energy it gives out in the form of a hydrogen rocket and it works perfectly. I have also used the carbon electrodes in a few electrolysis projects and they function great.

IMG_7078[1]
Here I am holding a battery before and after being taken apart. The black solid in the smaller plastic container is, you guessed it, the manganese(IV) oxide before being washed to remove zinc chloride and ammonium chloride. Also notice the zinc casing and carbon electrode to the right. All of the rubbish generated as seen in the top left can just be put into a small bag, tied up and thrown into the bin for disposal.
IMG_7206[1]
The manganese(IV) oxide after water washing and drying outside for a week or so. It has been appropriately stored in an air tight container with labelling I designed and am still refining.
IMG_7207[1]
The four zinc casings – I may eventually melt them down into a single block.
IMG_7208[1]
The four carbon electrodes collected are on the right. They are stored in a contain with the rest of my carbon electrodes, all scavenged from batteries: the smaller from Zinc Chloride AAA batteries and the larger from a Carbon Zinc 6V lantern battery.
 

Further reading or watching:
Youtube channel NileRed – Getting Manganese Dioxide, Zinc and Carbon from Batteries:

YouTube channel NurdRage – Get Zinc, Carbon Electrodes and MnO2 from a Lantern Battery:

Kodak Zinc Chloride batteries material safety data sheet

Click to access 4667875.pdf

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