Zinc bromine battery
see also Zinc bromine battery research
In the comparison of battery types (search the wiki) it became apparent that Zinc bromine may in fact be a very promising option for OSE puroses:
- It is an old technology, more than 30 years old.
- It is more efficient than nife. 75% for existing batteries but this might be increases to 80 by designing for efficiency, 82% theoretical max i.e. using ion exchange rather than porous separator membranes, using single, non-flow cells that do not share electrolyte. Big impact on cost.
- Extremely cheap: in 2 places have seen in quoted that production cost including labor etc to the mfgr can be about $28/kWh (so the cost at the factory gate).
- Common materials: zinc pretty common and bromine commercially extracted from seawater. Plastics seen in docs are not exotic, polyethylene etc. Carbon electrodes sound very easy to make.
- Easier to produce : no packing of active materials into the electrodes of need to worry about particle sizes etc, just solutions. No flits. No electroplating.
- Reasonable density, 3 to 4 times that of lead acid
- Easy to rebuild
- Low toxicity materials and components, zinc very low toxicity and bromine not bad though don't want to breath it.
Issues remaining that shoudl be clarified
Vapor pressure above the bromine solution: if higher than atmospheric a bit of a safety prob
Sealing? how much gas is evolved and is the chemistry amenable to recombination without a noble metal catalyts? Usually in flow batteries when it is fully charged the electrolyte doesn't have much in it any more and so is not very conductive, preventing overcharge and associated water electrolysis. There seems to get very little mention, but there is some in the doc from ottawa U that mentions quite small amounts are evolved. need to check again how much 1.8 ml per cycle but for what size capacity.
lifetime limiting issues. A number of pages indicate that there are a couple potential issues but the commercial batteries appear to have resolved them, achieving 20 year lifetimes Zbb energy, we need acess to journals again to work them out in reasonable detail (this is clearly going to be a problem on not just this but many projects, something should be done to secure access, a library access team like the CAD team would be good):
attack of the plastics by the bromine, solved by finding good plastics compatible
loss of activity of the bromine electrode somehow - elsewhere is mentioned adding ammonium functional groups to it (attached by adsorption presumably) to catalyze the reaction.
instability of the electrolyte
Instabiilty of the membrane. Stable membranes have apparently been found. They can just be microporous for 80% eff in passive batt according to ottawa U doc, fill the pores with ion permeable material is an option and also using ion exchange membranes, thick enough.
searched for info on non-flow batteries and found only the following:
Pritam Singh, Bjorn Jonshagen, Zinc---bromine battery for energy storage, Journal of Power Sources, Volume 35, Issue 4, September 1991, Pages 405-410, ISSN 0378-7753, DOI: 10.1016/0378-7753(91)80059-7. (http://www.sciencedirect.com/science/article/pii/0378775391800597)
David Ayme-Perrot, Serge Walter, Zelimir Gabelica, Sabine Valange, Evaluation of carbon cryogels used as cathodes for non-flowing zinc-bromine storage cells, Journal of Power Sources, Volume 175, Issue 1, 3 January 2008, Pages 644-650, ISSN 0378-7753, DOI: 10.1016/j.jpowsour.2007.09.076. (http://www.sciencedirect.com/science/article/pii/S0378775307020046) Keywords: Zinc-bromine cell; Megaloporous carbon cryogels; Energy storage
Modeling of Zinc Bromide Energy Storage for Vehicular Applications Manla, E.; Nasiri, A.; Rentel, C.H.; Hughes, M.; Univ. of Wisconsin, Milwaukee, WI, USA
This paper appears in: Industrial Electronics, IEEE Transactions on Issue Date: Feb. 2010 Volume: 57 Issue:2 On page(s): 624 - 632 ISSN: 0278-0046 References Cited: 12 Cited by : 3 INSPEC Accession Number: 11054644 Digital Object Identifier: 10.1109/TIE.2009.2030765 Date of Publication: 28 August 2009 Date of Current Version: 12 January 2010 Sponsored by: IEEE Industrial Electronics Society Abstract
Energy storage devices such as lithium-ion and nickel-metal hydrate batteries and ultracapacitors have been considered for utilization in plug-in hybrid electric vehicles (HEVs) and HEVs to improve efficiency and performance and reduce gas mileage. In this paper, we analyze and model an advanced energy storage device, namely, zinc bromide, for vehicular applications. This system has high energy and power density, high efficiency, and long life. A series of tests has been conducted on the storage to create an electrical model of the system. The modeling results show that the open-circuit voltage of the battery is a direct function of the battery's state of charge (SOC). In addition, the battery internal resistance is also a function of SOC at constant temperature. A Kalman filtering technique is also designed to adjust the estimated SOC according to battery current. googel found the mentino in the body text
Modeling of zinc energy storage system for integration with renewable energy This paper appears in: Industrial Electronics, 2009. IECON '09. 35th Annual Conference of IEEE Issue Date: 3-5 Nov. 2009 On page(s): 3987 - 3992 Location: Porto ISSN: 1553-572X E-ISBN: 978-1-4244-4650-6 Print ISBN: 978-1-4244-4648-3 References Cited: 17 INSPEC Accession Number: 11139564 Digital Object Identifier: 10.1109/IECON.2009.5415330 Date of Current Version: 17 February 2010 Abstract
Utility scale energy storage devices have been considered for integration with renewable energy systems to improve their sustainability and dispatch. In this paper, we analyze and model an advanced zinc energy storage device (ZESS), for grid level applications. This energy storage system has high energy and power density, high efficiency and long life. A series of tests have been conducted on the ZESS in order to develop an electrical model that describes its behavior. The modeling is based on the observation that, at constant temperature, both the open circuit voltage of the ZESS and its internal resistance are exclusive functions of its state of charge (SOC). Since the value of the SOC is crucial to the developed model, and due to the inexistence of charge sensors, Kalman filtering is used to estimate the SOC of the ZESS at any operating point. The model and the SOC estimator are necessary blocks to use when integrating the ZESS with some renewable energy system so that the controller can decide whether the ZESS should store/release energy from/to the system. again in the body text
also there was one PDF that was accessible http://www.ruor.uottawa.ca/fr/bitstream/handle/10393/9521/NN00593.PDF?sequence=1
Zinc bromine battery for energy storage - has praise for a non flowing battery for remote energy storage but no details Modeling of Zinc Bromide Energy Storage for Vehicular Applications
Evaluation of carbon cryogels used as cathodes for non-flowing zinc–bromine storage cells
LIFE-TESTING OF 1.7 kW h ZINC-CHLORIDE BATTERY SYSTEM: CYCLES 1 - 1000
PERFORMANCE ANALYSIS OF ZINC-BROMINE BATTERIES IN VEHICLE AND UTILITY APPLICATIONS F. G. WILL and H. S. SPACIL General Electric Corporate Research and Development, P.O. Box 8, Schenectady, New York 12301 (U.S.A.)
PERFORMANCE OF ZINC/BROMINE CELLS HAVING A PROPIONITRILE ELECTROLYTE
DEVELOPMENT OF ZINC-BROMINE BATTERIES FOR UTILITY ENERGY STORAGE Gould Laboratories -Energy Research
Demonstration of a Zinc Bromine Battery in an Electric Vehicie David H. Swan, Blake Dickinson and Murali Arikara University of California, Davis and Gerd S. Tomazic S.E.A. of Austria
ZINC/BROMINE BATTERY DEVELOPMENT - PHASE II Exxon Research and Engineering Company, Box 8, Linden, NJ 07036 (U.S.A.)
ZINC/BROMINE BATTERY DEVELOPMENT - PHASE III Exxon Research and Engineering Company, Box 8, Linden, NJ 07036 (U.S.A.) (a section of the samd doc as the phase 2 one apparently, but it is missing pages)
checkout the patent on the research page assigned to Zbb technologies for a non-flow zinc bromide battery. I did not search for "convective flow" or anything though yet.
Okay, it looks like Zn Br is superior in all ways to nife pretty much, except a bit lower cycle durablility maybe (although there are companies with batteries they claim last 20 years in the context of single household photovoltaic systems). Except the chemistry doesn't quite fall into our laps as much. The plastic has to be a bromine resistant one which is not that special but has to be identified (could analyze the commercial ones etc. essentially is known in the art if not to us quite yet.), making the bromine electrode last is also certainly known in the art etc. They are a developed technology, in other words.
The possibility of a non-flow battery (cell), (passive, convection flow) could eliminate the complexity of a flow battery. The electrode could extend throughout the entirety of the electrolyte tank volume, or electrolyte could be transferred by convection to the reaction zone.
Or, an idea to prevent the shunt currents in flow batteries (electrolyte has to flow from one cell to another an some current flows unwantedly along the fluid path when the 2 cells are connected in series) is to use a small roots blower/gear pump like mechanism, very simple, only 2 parts and it allows fluid flow while interrupting the electrical connection path. The roots blower mechanism might also make a convenient pump. I envision a small module which contains the roots blower mechanisms and one of them has magnets embedded in the vanes. Exterior to the module a set of electromagnets which is the stator, can be used to turn the vanes and provide pumping.
One problem might be shape changes in the plastic as it is exposed to bromine, but maybe not if the right plastic is used, such as a plastic that is fully brominated to begin with. In any case the roots blowers would improve the electrical resistance to fluid flow resistance a great deal, improving efficiency of the flow module significantly.
Another cool thing about flow batteries is that they can act as inverters by switching between different cell configurations rapidly. Probably not a very good waveform, but certainly useable.
The microporous membranes should not be a problem. One way to make the is to take a die of the right shape and simply deposit the plastic on it in a thin film with solvents. Ion exchange membranes might also be easy to make instead and be slightly more efficient.
All things considered they look very promising and localizable. Just have to track down the details of the knowledge of them, which is mostly publically available in journals etc. Gregor 20:12, 24 June 2011 (PDT)
updates on progress
I am currently looking into better separators as the bromine diffusion across the separator appears to be quite high, the docs from ZBB technologies (library section modeling ones) show that a 50 kw module looses 2.8 kw or so at full charge and there is a graph that shows what it is including shunt current losses but it is mostly the bromine diffusion (which is the bulk of wha tis called transport losses). So it is very high, for the nonflow battery in the sandia second phase doc the self discharge was in the range of 1 percent per *hour* due to this diffusion. A flow battery can be shut down to avoid this loss to some degree, but if it is being used at all it will be there. But there are ways of dealing with it including using propionitrile in the catholyte (bromine containin electrolyte), different tyes of separators, and shutting down different sections of a flow cell (and maybe nonflow battery) when they are not being used. Shutting down entails depriving the cell of bromine so whatever is in the cell can still be wasted but no more. For nonflow some sort of shutter thing would be needed in front of the separator.
I have asked some of the people who can obtain journal articles to obtain some articles that describe various methods of dealing with this problem and will read them when I get them.
Bromine gas and compounds dose-response relationship
Probably compounds are unlikely to form but this needs to be checked
Odor: Bromine has a disagreeable odor at a level that was mentioned in the battery development part 1 document , I think it was 35 ppm or so, was well below the acute fatal level.
Ideally the total dose- response relationship for a wide range of dose rates and patterns over a wide range of time periods for a wide range of people should be nailed down. Both for inhalation and skin exposure. That's probably more than we can expect though you'd think it would be available for something like an element.
The vapor pressure above the complexed bromine catholyte is well below atmospheric pressure (what exactly? was a graph in the phase 2 doc) even at full charge (when it is highest). A hole in the case would only allow quite small amounts of gas out. The main issue is if the catholyte spills and gets on skin or the bromine evaporates out and is inhaled.
Th only other hazard of a toxic gas in a household I can think of is muriatic acid (hydrochoric acid at about 31% solution) (what is the vapor pressure of HCl above it?) and the more common hazard of the ammonia refrigerator, in which the ammonia is well above atmospheric. These should be researched some for comparison purposes. I have heard that ammonia from fridges blinded the people in the house if there was a leak during the night and this is why ammonia was phased out, but this may not be true. BTW there may be 2 types of ammonia fridges, the Rankine type and the adsorption type. What other hazards are there involving toxic gasses in the home? Carbon monoxide in some cases.
Remember the boiling point of bromine is around 60 degree C, so it is not entirely correct to think of it as a hazardous gas, except it evaporates pretty well. Under low temperatures like in winter outside the vapor pressure might be lowered enough to provide significant safety improvements.