Nickel-Iron Battery/Research Development
Did some googling around and making notes, here is what I found :
-apparently their efficiency goes *up* with time over about 2 years 80% as mentioned in the forum, unknown exactly why would be nice to know -see the docs from the manufacturer's of the modern batteries seems like efficiency is reasonably high actually, was not able to determine if the charging efficiency is nearly equal to the round trip efficiency, so the graphs might paint an overly rosy picture, but I think it is pretty close http://www.changhongbatteries.com/Ni-Fe_battery_for_Solar_&_wind_appliances_p53_m2.2.1.html
low quality taken from browser history: http://www.beutilityfree.com/content/index.php?option=com_content&view=article&id=106:Ni-FeFAQ&catid=42:Nickel-Iron%20Batteries http://www.green-trust.org/wordpress/2010/07/14/american-made-nickel-iron-nife-forever-batteries/ http://www.ironcorepower.com.au/page3.php http://www.varta-automotive.com/index.php?id=87 http://www.ehow.com/way_5993981_homemade-edison-cell.html http://ps-survival.com/PS/Batteries/NiMH/Iron-Nickel_Battery_2008.pdf http://www.electro-tech-online.com/renewable-energy/100471-building-good-working-capacity-ni-fe-battery.html http://www.incompliancemag.com/index.php?option=com_content&view=article&id=56:the-lost-almost-technology-of-the-edison-cell&catid=29:just-for-fun&Itemid=138
higher quality http://www.nickel-iron-battery.com/
http://fieldlines.com/board/index.php?topic=144379.0 says "combiner caps" catalytic caps are available http://sustainabledesignupdate.com/2010/02/green-battery-design/ says they have/had a team developing them I emailed them http://apptechdesign.org/contact-us/ as asking for any documentation they can send on their work
http://www.solarpowerforum.net/forumVB/off-grid/4509-nickel-iron-batteries-8.html on one page here includes list of manufacturers that currently make them
the product pages etc form blog post http://www.uni-regensburg.de/Fakultaeten/nat_Fak_IV/Organische_Chemie/Didaktik/Keusch/chembox_edison-e.htm more
Swedesh pat.Nos 8.558/1897, 10.177/1899, 11.132/1899, 11.487/1899 and German Patent No.110.210 /1899. US.Pat No.678.722/1901, 692.507/1902 and German patent No 157.290/1901 http://edison.rutgers.edu/patents/01488481.PDF didn't look at http://www.patents.com/us-4330603.html
may be other patents, companies that make them and search freepatentsonline using the advanced search function for assignee name may turn up more and more recent
This is good stuff, but it shouldn't be on the talk page, it should be in something like Nickel-Iron Batter/Research. - Mark Norton
Oh, I didn't know that page existed. It should be linked to from the nickel iron battery page. I think using "related pages" as done in wikipedia more often would be a good idea. I will do it now. Okay it has been moved and I will add the link in related page section. -gregor
more on nickel iron ChangHong searched on freepatents online nickel iron electrochemical cell[p] nickel iron battery[p] nickel-iron battery[p] nickel iron cell nickel iron secondary cell nickel iron AN/changhong nickel iron AN/varta (changhong website says tehir battery tech is made from varta nickel oxyhydroxide battery at this there are many on nickel zinc batteries too might be useful bu tmost were omitted from notes below nickel oxyhydroxide electrode nickel oxyhydroxide battery
a lot on nickel zinc but since the cathode material is the same might be useful but most were omitted form below since there are so many
went through the first pages of results, got surprisingly few given how old these are, the search hits were usually very low relevance by the end of the first page so didn't continue past there though there were some on nickel zinc
assingee changhong also the related patents thing on the patent webpages might be useful to find even more
maybe email the suppliers through alibaba to see who own the technology base and if they have any documentation
high quality http://www.freepatentsonline.com/3853624.html
http://www.freepatentsonline.com/0827297.htmlthis one number wa sobtained from http://www.beutilityfree.com/content/index.php?option=com_content&view=article&id=106:Ni-FeFAQ&catid=42:Nickel-Iron%20Batteries notice that older patens are not searchable by the contents of the text unfortunately so any other edison patents may not be findable through patent search
battery grade nickel hydroxide http://www.freepatentsonline.com/5788943.html http://www.freepatentsonline.com/7407521.html process to produce nickel hydroxide maybe not useful thogh http://www.freepatentsonline.com/7081319.html preparation of nickel oxyhydrozide with ozone suitable fo use n battery (ozone is easy to produce with high voltage electrodes) http://www.freepatentsonline.com/4064331.html iron electrodes for battereis unk[p]
lower quality:[p] http://www.freepatentsonline.com/0678722.html edison us patent fist one metioned in wikipedia also appears to be on nicad not nickel iron http://www.freepatentsonline.com/0692507.html second one mentioned appears to be on nicad batteries not nickel iron http://www.freepatentsonline.com/6193871.html forming nickel elecrtode http://www.freepatentsonline.com/6492062.html nickel zinc http://www.freepatentsonline.com/7691531.html nickel hy more nickel zinc tells about nickel oxydydroxide lelectrode though http://www.freepatentsonline.com/6991875.html nother nice=kel zinc http://www.freepatentsonline.com/6261720.html have no idea if this is useful, something about a nickel hydroxide electrode in alkaline battery though I think this is probably be applicable to nickel metal hydride only ther eare many on nickel hydroxide electrodes http://www.freepatentsonline.com/4207383.html iron electrode maybe not useful there also appears to be alot of patents of more generalized approaches to e.g. the mechanical structure of the lectrodes of a secondary flooded cell battery which may be useful , on recombining hydrogen and o2 produceed by overchargning etc. http://www.freepatentsonline.com/5200282.html electrode ratehr than plates if wanted high disshcarge currents m\aybe http://www.freepatentsonline.com/7435395.html on nickel zinc
emailed http://apptechdesign.org/contact-us/ again on may 15asking for documentation on nickel iron
more links http://www.youtube.com/watch?v=K84PywMwjZg didn't watch indivudual says has read mulitiple edison patents coudl contact them to ge tnumbers and advice, couldn't find a way through youtube
all things considered there seem to be very few patents related to nickel iron batteries, but a lot more on nickel zinc for some reason, also this searching through patentsonline did not unearth the edison patents so there is room for improvement in the search method. Also the swedishand german patents should be retireved and translated though I assume they would be in swedish or german so I did not do that. There are probably more edison patents to be uncovered.
What is a "chemical short"? thermal runaway type thing? Nickel iron is known to be prone to thermal runaway need to know the electrochemistry involved here
It appears that as usual the electrochemistry of a good rather than crappy battery is not so simple, especially over a large number of charge/discharge cycles.
Clearly a chemist or someone else with significant expertise is needed here to work out the details. For example sulfur from vulcanized rubber can contaminate the battery chemistry apparently. IIRC steel has a small quantities of sulfur in it so using sheet metal as the anode might not work out although that of course remains to be determined....
On may 17 I had another look for useful information:
There may be one or two duplicates here, in many cases for scientific docs those look like the most interesting but I did not have access to them. Someone with access could perhaps retrieve them and share them with developers who ask under fair use I think.
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TH1-43MDKGV-3T&_user=10&_coverDate=02%2F28%2F1990&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1754749372&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=fbe875e250bbedd5c9c31cc21f22158d&searchtype=a http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TH1-43MDRN3-67&_user=10&_coverDate=04%2F30%2F1991&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1754737867&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=6cd39f8af38d365d4f7f3c3310c19022&searchtype=ais
In many cases docs were focussed on weight and discharge rate, but that is not out main concern, mainly $ per kWh and cycle life, with a discharge rate of at least 0.3 C (i.e. 300 watts for a 1kWh batt) it would work okay for pure solar systems, for biomass a higher discharge woudl be nice as it's primary function is to level the load on an hourly and daily basis at relatively high powers so a higher discharge rate could allow a smaller battery (whereas with pure solar you need a battery big enough to last for 3 days anyway and therefor even if the discharge rate as a fraction of capacity is low that is not a problem since the battery is so big anyway). However because batteries wear out partly as a function of the energy dumped into/removed (also ambient temperature but this will vary depending on the precise details of the battery, on ironedison.com it indicates substantial loss from elevated temperatures but the precise reaction that causes this needs to be identified) from them they may be considered on both a capital cost and running cost basis. Higher discharge rates will not in themselves affect the running cost, only capital cost, which may or may not be relatively small, that would need to be considered before effort is expended to produce a battery that would be okay with higher discharge rates. Secondly, there are no hard and fast rules on discharge rate for a given battery except to prevent overheating and achieve good energy efficiency, or for unusual reasons which are chemistry specific. The rules of thumb listed in battery datasheets are computed based on thermal characteristics, internal resistance of the battery (the higher it is the lower the discharge/charge rate you woudl want because Ohms law applies, therefore higher currents result in higher resistive losses) and in some cases unusual battery chemistry details like high speed charging resulting in wierd crystal structures of the anode or dendrite growth. Usually a battery can be operated above the rated charge/discharge rate as an engineering compromise though, which should be kept i nmind
In an OSE context it may no longer make sense to talk about battery cycle life in the same way. In a consumer context when a battery goes dead you get a new one, in some cases paying to get rid of th old one. And yet the active materials have not dissapeared. However there are sometimes irreversible side reactions that occur, changes in chemistry, the electrode that was supposed dto provide mechanical sterngth etc has dessolved, etc. For lead acid batteries there is information available on this of course. What is it for nickel iron? There is a whole industry based on rejuvenating "dead" lead acid batteris though clever chemisttry techniwues etc. and perhaps analogous techniques shoudl be worked out for nickel iron as part of this project. That could help to substantially decreae the effective running cost fo the batteries. There may already be a lot of information in existence to be drawn upon as these batteries have be used since they were invented in niche markets such as european mining, and in China, rather than as it is portrayed as beign forgotten.
By the way from what I have read this stuff about batteries lasting 50 years that some manufacturer's claim either includes this maintenance or it is bunk. They may last 3, 4 or 5 times as long as lead acid but certainly not 50 years of daily use without some kind of serious maintenance.
something about activatign the iron electrode,
patent number 5,788,943 Aug. 4, 1998
[54] BATTERY-GRADE NICKEL HYDROXIDE AND METHOD FOR ITS PREPARATION this one might have been already noted elsewhere
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TH1-4679T4B-1B&_user=10&_coverDate=08%2F31%2F1995&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1754734072&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=84892d5964e609a899d54fbde534666c&searchtype=a good info on cycle life of exisyong cels
"battery grade nickel oxydydroxide" mayb be many such patents or the same on ekeep sseing
nicckel/iron
Battery-grade nickel hydroxide and method for its preparation B Aladjov - US Patent 5,788,943, 1998
higher quality: http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5525702 pdf seems to be here free http://www.nickel-iron-battery.com/sealed-nickel-iron-battery.pdf http://www.nickel-iron-battery.com/nickel-iron-cycle-testing-1995.pdf cyle testing http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TH1-43MDJS6-2N&_user=10&_coverDate=09%2F30%2F1994&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1754797265&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=d2f1168545feacb1d7834ffd30cf729b&searchtype=a http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TH1-43MDSPY-6S&_user=10&_coverDate=06%2F30%2F1991&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1754794033&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=96fe8af78e49f181bae86df2a1085081&searchtype=a
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TG0-3Y0SH11-B&_user=10&_coverDate=02%2F29%2F1996&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1754792458&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=c47dbade5e61e0f4de4ac3707698bafe&searchtype=a coudl eb wuite iomportant, lithium hydroxide is often added to nickel iron batteries and this explains why , but litium is actually quite toxic (used as mood stabilizer for depression etc.) so shoudl be avoided if possible or unless the amounts are quite small, maybe sustitues can be found or maybe the edison batteries do not use it and are fine so it can be omitted. Also it is yet another component to add to the system and synthesize which is bad for OSE, how common is lithium in the environment?.
http://www.google.ca/patents?lr&vid=USPAT2653180&dq=nickel-iron%20%20battery&printsec=abstract&id=9mRlAAAAEBAJ&output=text&pg=PA2 on a battery itsself looks like a good one http://www.google.ca/patents?lr&vid=USPAT4680241&dq=nickel-iron%20%20battery&printsec=abstract&id=ACEvAAAAEBAJ&output=text&pg=PA1 good info too and method of restorign lost capacoty
http://www.google.ca/patents?lr&vid=USPAT3507696&dq=nickel-iron%20%20battery&printsec=abstract&id=tQ0hAAAAEBAJ&output=text&pg=PA2 interesting but has some funny parts like saying oxidization not known from th 70s maybe thats why explains iron passivation of leecctrode this coudl be important
lower quality:
http://www.freepatentsonline.com/3911094.html producing nickel oxydydroxide also discusses self discharg mechanisms of anode interesting but not needed migth reduce self discharge rate
There area many patents on the nickel electrode geometries and how to make them ususally intended for nimh or nickle zinc but coudl be used for us too, though again the perforated pockets are porbbaly adequate for our purposes anyway, they are usually intended to solve problems like low energy density etc which is not amajor problem for us anyway( http://www.google.ca/patents?hl=en&lr=&vid=USPAT4844999&id=ujE1AAAAEBAJ&oi=fnd&dq=nickel+iron++oxyhydroxide+battery&printsec=abstract#v=onepage&q&f=false http://www.freepatentsonline.com/EP0587973.html http://www.google.ca/patents?hl=en&lr=&vid=USPAT5861225&id=8LEYAAAAEBAJ&oi=fnd&dq=nickel+iron++oxyhydroxide+battery&printsec=abstract#v=onepage&q&f=false )
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V3F-50P47KJ-2&_user=10&_coverDate=09%2F30%2F2010&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1754805309&_rerunOrigin=scholar.google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=e286d03850bd05025a213e592d004af5&searchtype=a making ni(oh)2 electrodes: http://www.freepatentsonline.com/EP0723305.html
[ii] Patent Number: 4,863,484 [45] Date of Patent: Sep. 5, 1989
[54] PROCESS FOR PRODUCING BATTERY ELECTRODES BY ELECTROCHEMICAL REDUCTION
I hit the motherlode this time:
http://edison.rutgers.edu/battpats.htm
All (purportedly) of Edison's battery related patents, and it looks as though a large fraction of them relate to nickel iron directly or indirectly, from production of raw materials to the geometry of the electrodes. I started going through them but my computer is too slow. Most of them appear to be highly relevant; because he did not have high grade commodity materials to work with, this appears to be nearly an instruction book on making batteries from relatively low grade materials, although it might not be as good as a modern commercial one that remains to be seen, especially with a modest redesign combining the modern information above (and there is more like it I'm sure).
Cost of nickel oxide and hydroxide to determin if they might be cheaper than metal nickel in terms of the quantity of nickel:
Prices on the pages are FOB: free on board; assumption of responsibility by shipper for all costs until goods are placed on carrier , whatever carrier is, presumabbly the shipping company.
Ranges from 7 to 30$ on alibaba.com some grades migh tnot be suitable for batteris due to impurities, this can probably be determined from the information in the scientific articles and some manufacturer's conveniently say it is suitable for batteries. Detailed analysis may be available from suppliers. Samples may be obtainable form suppliers for prototyping with the specific material of concern. NiO2 (oxide) and Ni2O3 (peroxide) or NiO see wikipedia for CAS numbers but the pages sometimes fail to distinguish saying oxide always? http://en.wikipedia.org/wiki/Dictionary_of_chemical_formulas/Merge/N note that chemical suppliers are sometimes very sloppy about talking about chemicals and chemical names and may make mistakes, a lot of chemists are, with oxide meaning any of the oxides so need to double check the exact chemical used in the patents if the route of producing nickel oxyhydroxide from nickel oxide by oxidization in o2 gas, ozone in solution or humid ozone gas or otherwise, is chosen.
Details on which impurities are prorblematic needs to be tracked down so the cheapest stuff that will do can be used. Testing works to some degree but not if the impurity causes reduced life which would go undetected. Nickel hydroxide I did not check yet because I still need to look at other patents and see if electrode can be made straight from it.
alibaba, jus tsearch nickel oxide or "nickel oxide" battery http://www.alibaba.com/product-gs/406028137/Nickel_oxide.html
http://www.alibaba.com/product-gs/292513004/SHMMC_Nickel_Oxide_Ni_more_than.html
http://www.alibaba.com/product-gs/430054234/Nickel_oxide_74_.html 7$
http://www.alibaba.com/product-gs/241109238/Nickelous_Oxide.html
conclusion: In terms of nickel content, depends on who it is purchased from etc. But it is usually substantially cheaper than nickel metal.
The if vacuum is use for pasted equivalent electrode, battery could be designed such that the pasting process occurs inside the battery maybe no point though, but trying to keep the reactions and toxic materials in the battery during manufacture rateher than needing to pour and transfer them would be nice , and using nickel metal as a starter material coudl be a perk in that regard actually nickel oxide not soluble in water is it? No do not accept "insoluble" as an answer, want to know exactly how soluble
Is apparent that the reaction products stay put where the reaction material was before, unlike in a lead acid battery where they form a sludge of material at the bottom of the battery, that assumption tripped me up for a bit there so be it known.
http://academic.research.microsoft.com/Paper/11920038 solubility of NiO maybe post on amateur chemist forums when the time comes ask for help clearin up uncertainties, maybe experimenting like finding solubility of nickel oxyhydroxide or p
iron air battery sounds interesing http://www.freepatentsonline.com/4474862.html wonder what the efficiency for rechargnin is probably very low, could make a good electrid lifetrack
http://www.freepatentsonline.com/4335192.html ammonium halogenides suitable for activatin iron elecrtrode
http://www.freepatentsonline.com/4335192.html The classical method, dating back to Edison, for producing active metallic iron powder involves dissolving the pure iron in sulfuric acid, subjecting the iron sulphate derived from the solution to a baking process at 900° C., and reducing it in hydrogen current at 450° C. after washing and oxidizing drying. The iron powder so formed can subsequently be sintered either in the dry state or as a moist paste in an H 2 current after application to a support, and thus formed into an electrode. Later electrochemical processes for making active iron masses have also become known, e.g., in accordance with Austrian Pat. No. 320,770, which teaches the electrolysis of an iron nitrate solution, with copper salt added to it.
http://www.freepatentsonline.com/4443526.html nickelwhatever electrode "A very suitable material is nickel coated steel wool." for current collctor of cathode "As can be seen from FIG. 2, the cobalt containing electrode paste of this invention provides pasted electrodes which retain theoretical output of about 0.26 ampere-hours/gram for between 25 to 38 cycles, curves (A) and (B). Without cobalt additive, output drops to below 0.20 ampere-hours/gram of NiCO 3 ." So we don't really need the cobalt, good. Sounds like a good way to make an electrode then if Nico3 is cheap , is low solubility therefore lowtocix hazard according to wikipedia page thoug hmight not be reliable since they are not specifically talking about NiCO3 so better than loading electrodes with nickel hydroxide
http://www.freepatentsonline.com/4236927.html High curretn hihgly active more on a sintered iron electrode Numerous attempts have already been undertaken to maintain the polarization within acceptable limits, for example, in that one mixes active iron material with nickel flitter (very fine nickel flakes) as conductive substance and stuffs this mixture into steel pockets or small steel pipes. This electrode type is very stable and sturdy; however, it can be operated only with small current strengths.[the pocket electrode edison used? need to check edison patents he may not have added the flitter or used adifferent metallic material for conductivity]
"A simultaneous cathodic separation of iron and of a conductive material such as, for example, nickel, entails a further improvement; " what does this mean?
another sugested option might be mixing pure iron powder with sodium chloride solution,sintering adnduring sintering the sodium chloride prevents the particles from sticking together so much as to reduce the surface area more than needed, then removing the excess chloride by dissolving it, read in previous patents that this can help with leectrode activation as well as mentioned it corrodes small pores in the surface of teh iron , also in the process when sinterin gis done in an atmosphere of H2 activates the electrodes (removes oxide I think although not quite sure yet what electrode activation altogether necessarilly entails). Even better use feric chloride then rather than dissovling it reduce it with hydrogen gas to form iron apparently works well, Note that this may not have been tested for lon gterm urability but they are in the know and do no expect it to be a problem and why patent something unless pretty sure it is useful unless they are just putting up fences in case it might be useful, also the patent said that "The theoretical capacity with respect to weight of an iron electrode lies at 960 ampere hours per kg (Ah/kg). In practice, once reaches capacities of about 200 to 250 Ah/kg because" this indicates that the cost calculations for the raw material amount of iron is much higher than the naive electrochemical equations, it migh tals obe comparable for the cathode reaction which would be bad but from descriptions for other electrode producing methods this might be wrong or out of date (filed 1978) check with that starved electrolyte nickel iron battery paper to see if can extract data on the actual performance vs. theoretical that they acheived
note the tendency to use diffusion bonding to connect fibers involved with fiber elecgtroe plaques, in many cases no tmentioned but may be important. Can probably calculate bulk specific resistance with and without bonding, contact resistance between 2 metals just touching not bonded can be found in references.
http://www.freepatentsonline.com/4250236.html says lithium hydroxide not needed "tubular electrodes"? "bonded iron plastic elctrodes"? Maybe an electrically conductive polymer would eb convenient maybe with metal fibers embedden in it "The positive electrodes were intentionally made with larger capacities than the negative electrodes" it shoudl be the other way around, otherwise you risk reacting the entire iron electrode during discharge and the iron usually provides some of it's own current collector matrix, maybe they made a mistake or maybe they did it on purpose for testing or something.
http://www.freepatentsonline.com/4250236.html
still doesn't explain how the variation in electrode geometry changees with charg/discharge cycles, but it seems that it is assumed that it stays more or less the same for some reason i.e. an electrode that has a high surface area to weight ratio when new will continue to have one, and without the need for additives or anything like that. Maybe the hydroxide precipitates out right after being formed and stays more or less put on the surface, and likewise does nto travel far during charging though ther must be some diffusion and maybe this is part of what limits battery life. Alternatively on in combination with this, maybe the processes during reformation of the electrode during chargnine are remarkable symmetrical with the ones during recharging, leading to a very slow reduction in surface roughness/porosity, or it usually goes up over time so as long as you start high engouh to be good you're okay.
Still need to identify the temperature dependent capacity loss mechanisms http://www.freepatentsonline.com/4132547.html another electrode one for the iron electrode, there are so many am skipping most of them, they can be found by searching easily http://www.freepatentsonline.com/6335120.html polymer support matrix , helps explain the method used to make the electrode in the sealed nickel battery testing doc, applies to both electrodes, why would you add syncrystallized materials they mention? could semimelting of the polymer work to provide adhesion thereby replace some of the ingredients here reducing ingredient count?
Performance/capacity loss mechanisms identified thus far:
http://www.freepatentsonline.com/4236927.html I think mentioned that the interfaces between the iron particles in a sinterd electrode can oxidize with some electrode production methods, increasing the resistance of the bulk of the electrod's current collecting matrix to high level,
Oxidization of the iron to iron oxide causes electrode passivation, the addition of something to provide sulfide ions in electrode or the electrolyte causes reductino of the pxide on an ongoing basis, but eventually the sulfide oxidises to sulfate and doesn't go back,
http://www.freepatentsonline.com/4250236.html says passivation occurs more so at *low* temperatures, not higher , also points out depletion of sulfide is one mechanism by which it is due to oxidization of sulfide to sulfate
The marketing material for e.g. nickel-iron-batteries.com indicates that there is a reaction that occurs which produces capacity loss with time and is more problematic at higher temperatures. This has not been identified yet and should be.
Activation of iron electrodes: http://www.freepatentsonline.com/4250236.html so sound like pretty much a mattery of getting and keeepinng oxides off and keeping them off http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B9D09-4XS7F7F-1Y&_user=10&_coverDate=06%2F15%2F2010&_alid=1757708553&_rdoc=4&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=62089&_sort=r&_st=13&_docanchor=&view=c&_ct=2063&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=8cc228681b8c7fe749c54ac6ede1fad4&searchtype=a might be duplicate http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TH1-3VR6J5Y-2&_user=10&_coverDate=09%2F30%2F1996&_alid=1757708553&_rdoc=1&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=5269&_sort=r&_st=13&_docanchor=&view=c&_ct=2063&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=9d946a5af21722601c868ded3c95c8ed&searchtype=a might be duplicate
There are a great number of patents on electrodes, a lot to learn here for the background and a lot of good ideas. Apparently searching for nickel iron battery patents turns up very little but there are a huge number of good and valuable patents on the constituent parts and electrolyte which can be found with the appropriate search terms incormporating some knowledge of how the batteries work.
http://www.freepatentsonline.com/result.html?p=1&edit_alert=&srch=xprtsrch&query_txt=Iron+sintered+electrode+battery&uspat=on&date_range=all&stemming=on&sort=relevance&search=Search
No doubt this applies to searches in other venues as well like on sciencedirect etc.
While at first it appears there is relatively little info on these batteries there is a vast amount just under the surface that can be mined out and is fairly informative. Clearly after the information is mined out of the public spaces there will still be plenty left squirreled away by companies for one reason or another that is just not available to us. Some of this will need to be re figured out on paper by someone with some chemistry knowledge/ rediscovered though prototyping/testing/research.
aluminum air if coudl use aluminum elecrdodes from clay wonder how to make the gas permeable electrode though maybe coudl metallize a gas permable polymer layer with vacuum vapor deposition or similar or could maye the polymer slighlyt conductive and embed metallic fibers or similar
check out other ways to make active iron electrodes are probably lots of them, includes a low solubility sulfide mixed in the iron or added in excess to the electrolyte, adding sulfide to the iron electrode, other ways of getting sulfite where it needs to be, apparently present as an impurity in adequate amount in some iron anyway so thats handy.
nickel zinc might be worth lookin g into since they have higher cahrge/discharge efficiency are more efficient
http://edison.rutgers.edu/battpats.htm patent 01488480 describes some failure modes and fix looks like ause for the waste glycerine from biodeisel too
searchable archive of the pdfs which I ocred, I tried to upload this to the wiki but it is more than 7 megs and not a permitted file type (.zip) not can batch uploading of PDFs be done, so maybe someone else can put this information on the wiki where it will not disappear in the future as it will on zippyshare, but will rather remain conveniently searchable for future developers: http://www30.zippyshare.com/v/76183680/file.html
why is it that edison keeps mentioning that sulfur is undesirable in the vulcanized rubber in the insulators but in modern batteries is is used to acitvate the electrode?
yet another optio nfo the anode is to take copper crystals and iron particles and compress them into a blockL 2683182 says low purity iron can be used for this
http://www.freepatentsonline.com/5151162.html electrically conductive pollymers, maybe some of them would make sense as a conductinve substrate that's easy to make and low cost