Nickel-Iron Battery

This page is currently under construction and might undergo drastic changes within a short span of time.

http://en.wikipedia.org/wiki/Nickel_iron_battery

Basic Concepts Behind Construction

The electrochemistry of a Nickel iron battery is similar to a NiCd or NiMH battery in that nickel oxyhydroxide is used as an anode, but iron is used instead of the toxic metal complexes in NiCd and NiMH batteries. During discharge, both metals turn into their hydroxide forms: Ni(OH)2 and Fe(OH)2. (see the wikipedia article under electrochemistry). Given the resilience and rechargeability of the NiFe battery, it should be possible to build it in a discharged state, combining the appropriate hydroxides of Nickel and Iron. Alternatively, the battery could be constructed out of metallic nickel and iron, and the nickel should mostly convert to an NiOOH form after the first discharge-charge cycle.

First test

A sample concrete cell was tested, but no practical benefit is achieved using concrete as an electrolyte, as to be effective, the entire cell must be submerged, and the electrical conductivity of cement is far too high when submerged. A new design is in the works for a cell which would use raw glycerine (glycerol) as a byproduct of biodiesel production, thus improving the ecologies of both systems. The rationale is that the lye (KOH or NaOH) which 'contaminates' the glycerine should prove to be an effective electrolyte, and the glycerine itself should support a more stable cell. (Glycerine will evaporate much more slowly than water, and due to higher viscosity, should even further improve vibration-resistance of the cell. Ideally, this design could even be adapted to portable units.

Preliminary Figures for a 12V, 1kWh pile

NiFe cells produce a working potential of 1.2V, and charge at 1.4V. A 12V battery would then consist of 10 cells, and charge at 14V which is typical for most "12V" batteries. To achieve 1kWh capacity, we will need 1000W/12V = ~85Ah. This means that each cell will need to provide 85Ah capacity. This corresponds to 306,000C, which is approximately 3.17 moles of electrons. Sheet steel will form a base material for the electrodes, so iron is not a limiting factor. Nickel's electrochemistry in an NiFe battery indicates a 1:1 molar ratio, so 3.17 moles of nickel will be required. This is about 185g of Ni at a molar mass of 58.69g/mole. For a 'safety' margin, we will round up to 200g. At 200g Ni per cell, a total of 2kg of nickel will be needed for a 1kWh unit. The actual capacity of this cell based on the rounded values above would be 1095.8kWh.

Environmental Aspects

All batteries (at least the ones in common use) are toxic to a greater or lesser extent. The NiFe Battery isn't an exception, but it is far less toxic than Cadmium-based batteries.

• Iron is non-toxic and commonly available.
• Nickel Oxide is toxic. The Appropriate Technology Collaborative is investigating toxicity [1].
• The lye electrolyte is caustic and corrosive, but perhaps could be used in small amounts.
• Suspending the lye in glycerin also mitigates effects.
• Glycerin is a by-product of creating bio-diesel, thus using a waste of a different process.

Sources

FusionBeads [2] 3"x3" 24 gauge nickel sheet is $3.25.
Metric: 76.2x76.2mm and 0.5mm thick. The density of nickel is 8.902 g/cm3. 2903.22 mm3 which is 2.90 cm3. Thus, each sheet weights 25.84g. 2000g (2kg required as above) is 77.38 sheets. $251.50 is the cost of 2kg of nickel. Actually, it can be gotten cheaper in these quantities, but this is an outside number.

We need to look into purchasing in bulk as it is far cheaper than this sheet, although sheet could be used for electrode material. Those guys must be making generous profit to say the least.

Price of Nickel and Iron

http://www.indexmundi.com/commodities/?commodity=nickel price is very roughly $23 per kg. Pretty good really. http://www.steelonthenet.com/commodity_prices.html price $0.60 per kg for scrap steel, presumably pure iron would be in that range.

From the electrochemistry figures above for a 1 kWh unit, that would be $48 or so on metals. So 20 Wh per $ ($0.05 per Wh). Even the cheapest lead acid batteries are 7 Wh per $. In reality they are more like 4. So the good news it that materials cost should not sink the ship anyway, although I'm sure all the other costs for the perforated pocket, assembly etc. will add up plenty fast.

Toxicity

Nickel itself that is the concern rather than any particular compound. Water soluble compounds are unsurprisingly much more of a concern than metal that is bound in solid objects like nickel plating or some types of stainless steel, since it is more bioavailable and can be spread and spilled more easily. At low levels of exposure talking in terms of nickel content is done. But of course the exact solubility and other factors has a substantial effect on the exact toxicity at higher levels of different water soluble compounds too, note the ld50 is 10x lower for nickel chloride as for nickel oxyhydroxide according to the documents below, so the expedient of speaking in terms of nickel content doesn't always work that well.

Still all metals are toxic to some degree including iron and we need some numbers to make an informed decision. Preferably a solid evaluation of dose response relationship, and if the batteries are to be widely adopted now is the time to factor in chronic exposure too. It needs to be considered not in a vacuum but relative to other options available.

This is one of the benefits of batteries with non aqueous electrolytes apparently - the compounds involved in such batteries are less soluble in water since most compounds trend towards being soluble in aqueous or nonaqueous solvents but not both.

higher quality : http://jas.fass.org/cgi/content/abstract/28/5/620 http://www.annclinlabsci.org/cgi/content/abstract/11/2/119 http://www.hpa.org.uk/web/HPAwebFile/HPAweb_C/1236757324101 looks better but didn't read msot of it http://www.epa.gov/iris/subst/0271.htm https://fscimage.fishersci.com/msds/53189.htm http://www.nickelinstitute.org/index.cfm/ci_id/13029/la_id/safe_use_guide_5.cfm.htm

unkown due to lack of acess: http://www.ncbi.nlm.nih.gov/pubmed/19888907 http://www.annclinlabsci.org/cgi/content/abstract/7/5/377 Low quality: http://www.crios.be/Nickel/toxicology.htm material safety datasheets with information regarding nickel oxyhydroxide, clearly it is sometimes used as anode material in NiMH, in fact most of the hits are datasheets for such batteries rather than the material itsself: http://www.rdbatteries.net/Data/Panasonic_NiMH_Info.pdf http://www.chiefsupply.com/resources/msds/Moto-NiCd.pdf http://www.batteriesplus.com/msds/Duracell_Nickel_Oxyhydroxide_%20Batteries_NorthAmericaMSDS.pdf (as if companies would give accurate information on their own products) http://www.it.pg.com/productsafety/msds/fabric_and_homecare/duracell/Duracell_Nickel_Oxyhydroxide_Batteries_(North_America_MSDS).pdf

Note that the permissible exposure limits (PEL) for the material is about a fifth that of graphite, which we know is not too toxic though it might accumulate in the lungs I guess. Still there are a lot of variables there as most particles inhaled are not retained, depends on size etc etc.

Obviously the LD50 is quite low at 1000 mg/kg range. But that means little in terms of what happens at lower levels. For Chloride it seems to be in the 100 mg/kg range.

http://www.osha.gov/SLTC/healthguidelines/nickelsolublecompounds/recognition.html They fail to say dosages in critical places, this information is actually low quality

nickel chloride: http://www.sciencelab.com/xMSDS-Nickel_chloride-9926213

oxide:http://www.inchem.org/documents/ukpids/ukpids/ukpid70.htm

From Dietary information perspective: http://iom.edu/Activities/Nutrition/SummaryDRIs/~/media/Files/Activity%20Files/Nutrition/DRIs/ULs%20for%20Vitamins%20and%20Elements.pdf

"A Tolerable Upper Intake Level (UL) is the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals in the general population. Unless otherwise specified, the UL represents total intake from food, water, and supplements."

1 milligram per day for nickel, 40 for iron. Well that's to totally zero adverse effect level and there's probably plenty of room for more there. Nickel is probably available as a dietary supplement, I wonder what happens when people take too much.

http://www.eoearth.org/article/Public_Health_Statement_for_Nickel case report little more than half way down of people drinking 250 mg/liter (250 ppm) nickel welding, relevant to pocket production: http://www.crios.be/Welding/toxicology.htm Maybe it woudl be better to make the pockets without welding. Folding perforated sheets cleverly, sewing with nickel wire etc. plenty of other options that shoud lbe fine .

As usual it is difficult to obtain quality information on a health issue and it is very time consuming to wade through the crap and get some answers. Case reports, vague qualitative statements, condtradictions, paywalls, are the norm. Ideally a table of dose-response relationships for a range of different people over a wide range of doses would be obtained but whatever.

In summary it looks like it is certainly less problematic than lead or mercury, gloves, ladling or scooping rather than pouring dry materials, and working outside would more than suffice for me personally. Spills of solutions should be prevented.

Related pages

http://openfarmtech.org/wiki/Nickel-Iron_Batter/Research (the page was accidentally created with the lack of y typo, don't know how to change that)

http://openfarmtech.org/wiki/Batteries