Zinc bromine battery research

Overview
Research pertaining to Zinc Bromine Battery chemistry.

see also Zinc bromine battery

existing companies

 * RedFlow
 * Zbb energy
 * Primus Power http://www.premiumpower.com/aboutrfc.php

=Patents and notes thereon= http://www.freepatentsonline.com/4491625.html addition of chloride to improve efficiency

non flow zinc bromin ebattery see the thesis on e(starts with nn) and the cryogel one, looks like nonflow zinc bromine is not developed to a useable degree really thoguht maybe check around more may be advances the athors were not aware of the bromine stuff gets pretty viscouse, check the thesis one again to determine exactly how much, 18 mPa-s or so which may prevent the practicality of a non flow battery. brominated plastics? the sandia people just used polypropelene and got pretty good life

table 5-11 indicates wuite fast self discharge, too fast for practical use probably, 30 percent a day or so roots blower thing sounds good still

vapor pressure too hihg? no, they talk about bromine evaporation rate. it is present in both solution and the oily liquied complexed phase (what they mena when they say "2nd phase "is the solution one) so the vapor pressure of bromine in aqueous solution would reveal the vapor pressure, in any case it is less than atomospheric, the phase one sandia doc has a section of safety of bromine also includes pressure above the complexed catholyte and it is quite low less than 10 percent of atmospheric at high temps, also odor of bromine is distressing at pretty low levels still doesn't tell much about chronic exposure needs to be verified still

diiffusion across the porous membrane is a major problem, in the sandia load leveling phase 2 doc the nonflow battery shows the diffusion rate across the battery although they fail to say the capacity of the battery or the surface are of the bromine elecrode, the separator itsself is in page 21 table 2-7 but how high surface area do you need for a given power typically ? table 2-2 in the phase 1 doc revelas the net, which includes the thickness of the separators, probably the area is the same as the cell area in the modelling section which is 1170 cm2 so then 3.9 mol*10^-6/s of Br2 which from the chemical equation is  1 electron per bromine so then electrons per coloumb/(8*10^-6*avogadros number)=coloumbs per second lost due to diffusion, which is 6*10^18/8*6.2*10^17= 10/8 amperes so the figure shown after compensating for various thing smaybe th / was supposed to be a. . so really a lot like 1% per hour. when the unit is shut off the bromine resevoir can be disconnected though and you would still loose the bromine present in the flow unit but no more than that (which is not very much since the bromine electrodes are not 3d apparently and therefore the volume of catholyte in the flow unit can be quite low), but as long as are chargeing or discharging the battery have to tolerate this sort of loss (will be higher or lower depending on the concentration of bromine in the catholyte which depends on the state of charge a bit probably?) because the bromine reservoir has to be connected. To prevent this maybe a thick enough ion exchagne membrane would work. Need something with sufficiently high ionic condictivity to resistivity ratio which is also sufficiently resistatn to brimin eover the long term, bromine should not diffuse through it except by ion conduction which is perfect. also check the propionitrile catholyte thing and maybe other mixes which reduces self discharge also remember from patents there was some stuff about the possibility of coating the microporous separator with a gel also remember the part of phase to sNDIA doc with tests of exact bromine transport mechanisms, wetting and diffusion what about coating the separator with a material like propionitrile

There are a lot of different options here maybe on eof them will do, google scholar for "zinc bromine battery self discharge" and efficiency and bromine diffusion and separator, propionitrile, and maybe more can pick up from reading docs, searched zinc bromine battery "ion exchange" and found:

the whole table of the modellinghting is probably messed up as the watt hours in/out is completelly messed up they made a bunch of mistakes alsmost the only source of self discharge seems to be this diffusion, a thick enough ion exchange membrane might be quite valuable. The thermodynamic limit on effic as explained inthe sandia phase 2 doc is about 92% and judging from the diffusion of the nonflow battery (double check by calculating from mthe duffusion rate and the area of the separator) the diffusion is by far the main other source of innefuciency in the nonflow batt, and this is because it is self-discharging during the test cycling of the battery. Probably the same applies to the flow batteries too although they have shunt and pumping losses too. So for the simulator might mate sense to separate the self discharge and the actual charge/discharge efficiency.

The modeling section seems to reveal the design specs of the battery they shoudl really list them elsewhere if the phases separate naturally why not use that so only have to pump around the aqueous phase? then send it back to the reservoir to acheive equilibriu with the complexed phae again

patents, looks like we are okay there, no important parts for a high efficiency, long lasting, low cost are a problem for flow batteries, still havet to look into nonflow more.. can verify maybe. Comes down to a separator tha t is better than a microporous one a this point, need a good one that is also not patented to acheive low self discharge, ther are quite a few ways though so proabbly not a problem.

Check pictures to verify the relative size of modules?

what is baseline data The standard cycle used for gathering baseline data consists of three steps. First is a 4.5-hour charge to 105 Ah (90 mAh/cm2) at 23.3 A, followed by a discharge at the same current to a cutoff voltage of 1.0 V per cell. The third part of each baseline cycle is full strip to zero charge. This is done by shorting the cell through a resistor. The amp-hour information collected during the strip is used to determine the transport and residual inefficiencies, which are components of the coulombic efficiency. The transport inefficiency is the part of the coulombic inefficiency caused by chemical transport of bromine across the separator to the anode chamber, where it chemically reacts with the electroplated zinc. The residual inefficiency is the portion caused by zinc and bromine remaining in

Obatining the next batch of docs: David http://www.sciencedirect.com/science/article/pii/0378775388800818 ftz (non journal of power sources:

@TECHREPORT{1976eda..rept.....S,  author = {{Symons}, P.~C. and {Hammond}, M.~J. and {Birk}, J.}, title = "{Evaluation of a 1 kWh zinc chloride battery system}", keywords = {CHLORINE, STORAGE BATTERIES, ZINC COMPOUNDS, AMBIENT TEMPERATURE, BATTERY CHARGERS, ENERGY STORAGE, TECHNOLOGY UTILIZATION}, booktitle = {Interim Report Energy Development Associates, Madison Heights, MI.}, year = 1976, editor = "{P.~C.~Symons, M.~J.~Hammond, \& J.~Birk}", month = sep, adsurl = {http://adsabs.harvard.edu/abs/1976eda..rept.....S}, adsnote = {Provided by the SAO/NASA Astrophysics Data System} } http://adsabs.harvard.edu//abs/1977iece.conf..250W

http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=5861902 http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=7294745

interesting and maybe for later: http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=5546178 http://adsabs.harvard.edu/abs/1979psrd.symp..313W http://adsabs.harvard.edu/abs/1990STIN...9026251A not that interesting:

http://www.sciencedirect.com/science/article/pii/0378775388800041 http://www.sciencedirect.com/science/article/pii/0378775385800033