Revision as of 22:48, 26 August 2011

The Yahoo Group contains current efforts including a photo deck of his current battery. He also includes lots of other DIY projects that fit the theme here: DC motor control, Induction Furnace, Metal Casting, Electro-forming ...

Yahoo Group: http://tech.groups.yahoo.com/group/edsworkshp/
YouTube Channel: http://www.youtube.com/user/edsworkshop#p/u/14/CBGcdtAzzUE

Suggested Source:

Nickel Carbonate (Baily Pottery) approx $28/lb or less (depending on size of order)

http://www.baileypottery.com/clay/clays-chemicals.htm

noonco

Edison Battery Construction Nickel Iron‏ - YouTube: http://www.youtube.com/watch?v=K84PywMwjZg
Edison Battery Page: http://www.noonco.com/edison/

Chemistry

Handbook of Batteries, 3rd edition (more details available in that reference):

Fe + 2NiOOH + 2H₂O <---> 2Ni(OH)₂ + Fe(OH)₂ (first plateau)

3Fe(OH)₂ + 2NiOOH <---> 2Ni(OH)₂ + Fe₃O₄ + 2H₂O (second plateau)

The overall reaction:

3Fe + 8NiOOH + 4H₂O <---> 8Ni(OH)₂ + Fe₃O₄

Discharging is left to right, charging is right to left.

"Plateau" refers to a region on the voltage vs state of charge of the iron electrode.

In practical batteries the second plateau is not normally used for various reasons even though avoiding it entails adding a lot of extra iron.

Theoretical specific energy using only the first plateau:

55.8+32+2 = atomic mass of discharged iron = 89.8

58.69+32+2 = atomic mass of discharged nickel electrode = 92.69

1 electrons per molecule nickel hydroxide, so roughly 10^5 coloumbs per mole of electrons, 27.7 Ah at 1.2 volts (33.3 Wh) or so per mole, 182.49 g, so 182.48 Wh / kg theoretical with 100 percent utilization, including the water as a reactant but not the electrolyte (of which only a vanishingly small amount is theoretically needed).

Additives

- cobalt hydroxide is used to improve conductivity of the nickel electrode either by adding it to the nickel oxyhydroxide at manufacture or into the powder after, by e.g. coating the particle electrolytically to give them a higher effective conductivity without interfering with their reactivity too much (it does reduce it a little though so again there will be an optimum amount). It can also help to increase the fraction of active material that is utilized. 1 to 5% of the active material mass may be used for this. We probably want to avoid bothering with this.

- metallic cobalt to the metallic mesh, function needs to be checked, probably to improve contact resistance and reduce oxidization of the mesh and maybe reduce corrosion rate by electrolyte.

-sulfur, tellurium or selenium compounds are used to activate the electrode, see other reactions section

-carbon black is sometimes added to pocket plate electrodes to improve bulk conductivity of the active material mass

-graphite particles can also be similarly added for pocket plate electrodes

Construction

Anode Compound

iron plate - low carbon, mild steel (demo)
iron graphite compounded (Edison)
iron oxide

Anode Construction

plain plate (demo)
pocket plate with mesh inserts (Edison)

Cathode Compounds

nickel(III) oxide-hydroxide
nickel hydrate and pure nickel flake (Edison)

Cathode Construction

plain plate (demo)
pocket plate with mesh inserts (Edison)
generally nickel-plated rather than pure nickel

Nickel sponge
Sintered nickel powder
Nickel mesh/cloth

Electrolyte

potassium hydroxide
sodium hydroxide (alternate, lower voltage)
lithium (modern additive)

Cell Casing

nickel-plated steel box, rubber seals (Edison)
plastic box (modern commercial)
glass jars (demo projects)
pvc cylinders (Ed's Workshop)

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 1 coloumbs per second*3600 seconds per hour*85Ah*1/10^5 coloumbs per mole, which is approximately 3.17 moles of electrons. Iron is cheap and so is not a limiting factor. Nickel's electrochemistry in an NiFe battery indicates we get an electron per nickel atom, so 3.17 moles of nickel will be required with a hypothetical 100% utilization of active material. 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 1095.8Wh.

Other important reactions in the cell

If you want a good battery rather than a poor one, the side reactions and other reactions in the cell are the most critical factor, with the only second being electrode geometry/design. They are a fundamental part of battery design. These exclude the reactions that contribute to the output electrical energy to the cell.

These are what sap energy away, leading to poor efficiency and high self discharge, and partly what limits battery life. Some of them are used to counteract the undesirable ones.

There are others that need to be learned from the documents listed in the sticking points section.

- tellurium dioxide is a recommended additive but never seems to be used in commercial batteries, improves efficiency by reducing hydrogen evolution.

- mucic acid is another additive that can be used to reduce the hydrogen evolution when integrated into the iron electrode, by a factor of 10 during storage (reducing self discharge greatly). Not clear if it helps improve efficiency as the patent does not mention that, but hydrogen evolution is the main reason the energy efficiency is so low so maybe worth further investigation.

-self discharge due to oxidization by dissolved o2 (pretty small in magnitude)

-The iron being anaerobically attacked by water, about 1000 times larger in magnitude than the oxidation due to dissolved o2. This is the main reason the battery has such a high self discharge rate. Basically the conversion of iron plus water to iron hydroxide plus hydrogen gas.

- self discharge at the nickel electrode, need to check the mechanisms/reactions again probably relatively low since it is in nimh and nicad despite the same reactants present.

-corrosion of the metallic mesh by electrolyte, this may be one of the lifetime-limiting reactions that increases with temperature.

-oxidization of sulfide to sulfate and it's ensuing accumulation on the surface of the iron electrode, increasing internal resistance. Sulfide is also often used to keep the iron electrode active so when it is used up the battery dies.

-sulfides like iron sulfide, or in some cases elemental sulfur (S8), or compounds of selenium or tellurium is used to "depassivate" the electrode. According to patents and reference sources this consists of reducing non-conductive, non-active oxides like FeO on the surface of the electrode back to active forms. They also indicate that without these additives charge efficiency drops greatly and hydrogen evolution goes way up, unless high purity iron like carbonyl iron is used and even then they don't work for long unless sulfur is added. No information has yet been found as of june 3rd 2011 on the performance of selenium and tellurium as mentioned above, if it might be superior to sulfur. Probably not.

-Accumulation of sulfur on the surface of the iron electrode esp. at lower temperatures and high discharge rates. If the sulfur or sulfides (or maybe other additives) are incorporated into the structure of the iron mass they are released faster when higher discharge rates occur and this can end up being too fast for them to diffuse away, resulting in them accumulating as a solid on the surface of the electrode, and since they are insulating and block access to the electrolyte this is a problem. At lower temps the solubility is lower so they are more prone to precipitate out of solution. This is not a permanent effect, the compounds redissolve if given some time. The exact temperatures and discharge rates depend on the quantities of additive involved and the surface are of the electrode etc. but references indicate this a problem more in the 0 deg C range than room temperature and at relatively high discharge rates, like two or three times the rated discharge rate (how high? In milliamps per sq meter is probably a reasonable measure).

-deposition of iron in the nickel compound crystal structure <--needs more research could be important life limiting reaction.

-oxidization of the surface of metallic flitts to low conductivity nickel oxide. Edison had a problem with nonconductive layer on the flitts forming and didn't know what it was, maybe explained in later patents.

-carbonate and the other one in the battery handbook undesirable ions, note that carbon dioxide from the air will react from the electrolyte to form carbonate salts <-- need to add those other ones. Some docs on the desired list may help inform here.

-probably all kinds of minor undesirable contaminants, Edison mentions manganese, and high purity material like carbonyl iron is often used to avoid them, and similarly for nickel electrode. However this may be expensive or harder to produce.

-lithium hydroxide apparently improves the thermodynamic reversibility of reactions (improves overall energy efficiency) and slows down the iron poisoning of the nickel electrode maybe this indicates longer life and higher charge/discharge efficiency, we need a chemist who can identify other ways of improving esp the charge/discharge efficiency by identifying other acceptable additives that might work. Also maybe analyze modern batteries if they have high performance.

-evolution of gasses at the nickel electrodes during charging and also charge-stand, this could play into the low efficiency but may only be commensurate with other prerequisite reactions at the iron electrode and unpreventable in themselves.

-The air interface one that causes oxidization of the nickel metal and/or active material(?) of the electrode when there is an interface with the electrolyte and air, nickel electrode needs to be submerged. Another cause of self discharge if not designed right, plus can corrode the electrode or the nickel plating of it right through possibly leading to failure.

- a couple of abstracts of inaccessible documents seem to clearly indicate that accumulation of potassium/sodium carbonate and similar compounds (presumably produced by atmospheric co2 and impurities in makeup electrolyte) deposit on the electrodes and this is one of the first problems that limits cell lifetime for unsealed, conventional nife batteries. They may be rejuvenated if this is the case.

Need to add references. See additives section too.

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.

Note that nickel hydroxide, oxide and oxyhydroxide are all considered "insoluble" although obviously the chemistry here depends on them being at least a bit soluble. But that increases the safety margin a bit. It may be substantially higher under these alkali conditions though.

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.

higher quality :

unknown due to lack of access:

Low quality:

http://www.crios.be/Nickel/toxicology.htm
material safety datasheets with information regarding nickel oxyhydroxide, clearly it is sometimes used as a material in NiMH, in fact most of the hits are datasheets for such batteries rather than the material itself:
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 should be 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, contradictions, and 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 and especially powders should be prevented.

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 is slightly toxic.
The electrolyte is caustic, but a so-called starved electrolyte cell can be used in a sealed battery without degradation in performance if potential spills are a perceived problem. In this design only the minimum amount of electrolyte is used, and it is absorbed in a porous mat so there is no liquid that can escape. This is what an Absorbed Glass Mat (AGM) lead acid battery is, and it can be used here too. The cost of the mat is not insignificant though. For photovoltaic there may be no need, flooded cells could be fine.
Increasing the viscosity of the electrolyte with glycerin also could be used, similar in theory to a gel-cell battery. There is a cost of increased internal resistance for a higher viscosity electrolyte. It may also pose a problem with the amount of gas produced, which needs to escape from the region of the electrodes. The glycerin might reduce cycle life as it could degrade on one of the electrodes in the strong red/ox environment or contain contaminants.
Glycerin is a by-product of creating bio-diesel, thus using a waste of a different process. It may have other uses elsewhere in producing the active materials etc. too.

Note on efficiency measures

The charge/discharge (also called round trip and overall) efficiency is the performance parameter that we care about, of course. Hypothetically it should be equal to the charge efficiency multiplied by the discharge efficiency. In this case the efficiency is energy efficiency.

The charge efficiency is often quoted in absence of the discharge or overall efficiency, which is very annoying as it makes it harder to compare different battery designs that are mentioned in the literature. In marketing materials it is probably used in the hope the customer will erroneously assume it is equivalent to overall efficiency, since it is always higher than overall.

The discharge efficiency is rarely referred to in isolation for some reason, probably because it usually more or less commensurate with charge efficiency and can be computed easily from the overall and charge efficiency. Commensurate does not mean equal though.

Not energy efficiency:

Faradaic and coloumbic efficiency: see wikipedia article. Unfortunately it is apparent in patents and other documents it is apparently that this is in fact often, either due to ignorance or more likely sloppiness, used to mean charge efficiency or overall efficiency so watch out for this.

Polarization of the electrodes, see wikipedia.

Overpotential, see wikipedia.

Non-chemical factors affecting performance

At low temperatures with some iron electrode designs sulfur can accumulate on the iron electrode and increase internal resistance (designs which incorporate elemental sulfur, patents indicate this can be rectified by using a sulfide salt of low solubility like iron sulfide FeS).

The conductivity of the electrolyte goes up as the temp goes up. This is desirable but other undesirable reactions increase in rate at higher temps so there is a compromise there. Also this is one of the main mechanisms that can lead to thermal runaway during constant voltage charging as it can form a positive feedback loop. The solution is to just not use constant voltage charging, which is easy.

The factors like the energy to weight ratio and power to weight will of course tend to be affected by any non-reactant materials used to e.g. reduce cost etc, but fortunately those are of relatively little importance in the context of OSE for off grid electricity and farm equipment, although they may be important for the electric car. Basically we want to produce something that can replace lead acid which is cheaper, easier to work with and make and maintain, more durable with abuse and longer lasting, and not as bad for the environment. Ideally both for starting lighting ignition (SLI) batteries and also storage. Batteries described in documents can handle 6C and more without seriously hard to manufacture materials and additives so SLI is definitely an option. See related pages section. None of these require high energy density or power to weight ratio although they are always nice.

The fraction of active material that actually is utilized if low will reduce power and energy to weight and volume ratio. Can be affected by particle size, additives and also any particles of active material that are not in reasonable electrical contact with the current collector for whatever reason will remain unused.

The level of the electrolyte can if not maintained in a non-sealed battery, drop below the level of the plates, and the uncovered portion of the plate may remain unused, decreasing capacity until the electrolyte is replenished.

There is always some distance that the current needs to travel to get from the reaction area to the current collector, and to do this is has to pass along the active material. Therefore the conductivity of the active material is an issue which significantly affects internal ohmic resistance (the term internal resistance is often used to refer in a catch all way to the current draw vs. voltage output relationship even though this is due to many factors besides ohmic resistance). See wikipedia for polarization for more information that relates to the voltaic efficiency.

For a vehicle: Power to weight ratio is affected strongly by the surface are to weight ratio of the electrodes.

The pressure the casing needs to stand increases as the internal pressure dose of course, see sealed battery section, if sealed it will need to stand significant pressure and therefore be relatively heavy.

Nickel iron for electric vehicles

There is some interest in using nickel iron in electric vehicles as it can produce major long term cost savings compared with some types of lithium. Also, as discussed on the battery comparison page there are only enough known lithium reserves to make roughly 3 million electric car batteries, nowhere near enough. So clearly some other battery technology will be needed, it is just a matter of which.

In contrast to photovoltaic system, obviously power to weight ratio and energy to weight ratio (specific energy) are paramount. Power to weight ratio for bursts during acceleration can always be improved using an ultracapacitor or other storage system in parallel however, but specific energy is a fundamental limitation.

As discussed above, the theoretical limitations of the chemistry for specific energy is 182.5 Wh/kg.

The practical weight is increased by a variety of factors mentioned in the non chemical factors that decrease performance section.

Wikipedia indicates around 50 Wh per kg for flooded cells, but those cells are not designed for low weight so that could be improved upon quite substantially.

Changhong uses nife pocket plate cells for starting batteries (SLI) so obviously they are capable of high rates though it is not clear how high. The starved electrolyte, sealed battery document mentions 6C at substantial efficiency loss. The ultimate electrode for both these ratios is the microfiber metal plaque, essentially nickel fibers around 2 microns wide assembled into a sheet with 95% porosity or so but that may not be needed.

One issue may be the relatively large amount of heat produced during charging, which may be twice or more that of lithium ion, therefore limiting the charge rate, but probably not a major issue.

There are quite a number of papers I have come across whose abstracts describe nife batteries being used to power electric vehicles for city fleets etc. and development projects of various sorts to develop nife batteries suitable for vehicles. It certainly works, it's jut a matter of achieving competitive performance. Zinc bromine may be more suitable for vehicle use, for a variety of reasons.

The discharge efficiency matters relatively more here as overall energy efficiency is less important that for photovoltaic systems probably. The lower it is, all other things being equal, the battery will weight more as the amount of energy stored is lower than what gets to the load, so you'd need a bigger battery.

Related pages

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

@@ Line 350: / Line 350: @@
 [[Category: Energy]]
 {{GVCS List}}
+{{Category:GVCS}}

The Global Village Construction Set
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Agriculture	Tractor	Seeder	Hay Rake	Well-Drilling Rig
	Microtractor	Soil Pulverizer	Spader	Hay Cutter	Trencher
	Bakery Oven	Dairy Milker	Microcombine	Baler
Industry	Multimachine	Ironworker	Laser Cutter	Welder	Plasma Cutter
	CNC Torch Table	Metal Roller	Rod and Wire Mill	Press Forge	Universal Rotor
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Energy	Power Cube	Gasifier Burner	Solar Concentrator	Electric Motor Generator	Hydraulic Motor
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	Nickel-Iron Battery
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Transportation	Car	Truck

Key	Design	Planning	Prototype	Almost done	Full Release

Nickel-Iron Battery: Difference between revisions

Revision as of 22:48, 26 August 2011

Contents

Products and Projects

Commercial Ni-Fe Suppliers

Projects

Chemistry

Additives

Construction

Preliminary Figures for a 12V, 1kWh pile

Other important reactions in the cell

Toxicity

Environmental Aspects

Note on efficiency measures

Non-chemical factors affecting performance

Nickel iron for electric vehicles

Related pages

Navigation menu

Nickel-Iron Battery: Difference between revisions

Revision as of 22:48, 26 August 2011

Products and Projects

Commercial Ni-Fe Suppliers

Projects

Chemistry

Additives

Construction

Preliminary Figures for a 12V, 1kWh pile

Other important reactions in the cell

Toxicity

Environmental Aspects

Note on efficiency measures

Non-chemical factors affecting performance

Nickel iron for electric vehicles

Related pages

Navigation menu

Search