Talk:Lithium–air battery

Major updates

I drastically updated the article based upon a sandbox created by a group of graduate students for a course on Materials Chemistry at a large research university. The previous article had some poorly cited sections and some irrelevant information. The new sections cover any pertinent information that was removed from the past article. Na9234 (talk) 20:43, 13 December 2011 (UTC)

Theoretical and practical energy density difference

Could somebody explain in the article main reasons for difference between theoretical energy density of Lithium (11000 KW-h/Kg) and practical energy density of Li-air fuel cell (1000 KW-h/Kg).Is this only due to presence of electrolyte and weight of a case?But how much of electrolyte is there?!

The energy density of lithium only accounts for the mass of pure lithium, nothing else. A practical Li-air cell in its heaviest state (completely discharged) will have its cathode filled with lithium oxide (Li₂O) at best, which is only 42% lithium by mass (more likely lithium peroxide, Li₂O₂, is the cathode product - only 27% lithium). Beyond this, the cell must have a separator, electrolyte, packaging, conducting support in the cathode (lithium oxide and lithium peroxide are believed to be insulators). All told, this extra material will significantly decrease the practical energy density below the theoretical density of lithium oxide and lithium peroxide. --Jrhardin87 (talk) 19:29, 20 July 2011 (UTC)

Expected lifetime?

How long are such batteries expected to last? anything better than the ~500 cycles/-2 to -20% per year of normal lithium ion batteries? 86.43.88.90 (talk) 11:46, 28 January 2010 (UTC)

favorite Li?

While the article clearly favours Li-O type battery, presumably based on the statements of the scientists, I wonder whether Ca-O might in fact be better overall: -The voltage is even higher -There is more Ca on this planet than Li (which competitively may be used for nuclear fusion) -The weight increase when used in mobile applications is less prominent (the oxygen is incorporated into the cell upon reacting with the Li, and adds to the battery weight) Thyl Engelhardt213.70.217.172 (talk) 06:38, 21 October 2010 (UTC)

Cite it and write it. Who's working on it? What is published? We don't do original research here. Thre's nothing about them in the 2002 "Handbook of Batteries". (It's not like Li used in fusion power plants is going to be a major drain on the resource any time in our lifetimes...fusion has been "40 years away" for the last 50 years, and has produced nothing but thesis topics.) --Wtshymanski (talk) 13:19, 21 October 2010 (UTC)

This is the Li-Air battery page, not Ca-Air or metal-air. It doesn't make sense to discuss the advantages of CaO here. Should the Metal-air_electrochemical_cell orphan be promoted to Metal-air_battery (which currently redirects to Zn-air)? There are a number of metal-air battery technologies, and a general overview of the category would be a better place for a comparison of the different types of metal-air batteries. --Jrhardin87 (talk) 19:53, 20 July 2011 (UTC)

As indicated in the article, the theoretical specific energy of Ca-Air batteries is much lower than that for Li-Air. The slightly higher voltage is offset by a significant decrease in the capacity (the # of useable electrons per unit mass, i.e. Ah/kg), so that the total energy (which is voltage times capacity) is lower. So while the relative weight gain of a CaO battery on discharge is lower, this is only because the battery must be heavier to store the same amount of energy. --Jrhardin87 (talk) 19:58, 20 July 2011 (UTC)

Or not, provided that the shielding of the Li requires more -and hence heavier- material than shielding of the less reactive Ca. I'm just speculating, but I think it is worthwhile considering, if we ever step from science to engineering. Thyl Engelhardt213.70.217.172 (talk) 13:56, 29 February 2012 (UTC)

Can we make the article more accesable to the lay person plase?

This is a good article, but it's very technical in a lot of places. For the uninitiated, it's hard to understand. If someone could rewrite it in less technical language that a lay person could understand, that would be appreciated. —Preceding unsigned comment added by Allthenamesarealreadytaken (talk • contribs) 02:50, 13 May 2011 (UTC)

Please be more specific: list some or all of the passages you do not understand, or which you believe a layperson would not understand. Then we can focus on specific things that need improvement. One straightforward improvement is to add links on technical jargon. Then the reader can easily look up the definitions of unfamiliar terms. --Teratornis (talk) 17:36, 6 May 2012 (UTC)

Puzzle about reaction

I'm sure there's a good answer to my question, but it's not in the article and will puzzle many readers. It sounds like you're getting something for nothing, and also that there's contradictory information in the article. This may be just a misreading, but we need more information to understand this. The article talks about a 4Li + O2 → 2Li2O reaction, but also says no oxygen is stored in the battery. OK, none at the beginning, but does the reaction mean that oxygen in the form of Li2O *is* stored in the battery as it runs? In which case the battery would get heavier over time. Or, if this is somehow just a temporary reaction and the oxygen gets released again, then it sounds like we're getting something for nothing. The latter seems to contradict physics; the former seems to partially counteract the claim that the battery is so much vastly lighter than ordinary Li batteries if it in fact gets heavier as it runs (and does recharging the battery then essentially mean taking the oxygen out again?) Maybe both of these inferences are false; but then we need a more complete explanation of what's going on to be useful to readers.69.211.4.10 (talk) 15:10, 9 June 2011 (UTC)

It's just like a zinc-air battery; shiny metal turns to crud, and electricity is produced. The real trick would be turning the crud back into metal, but that's been very difficult even with zinc and so far has eluded researchers workign with lithium. --Wtshymanski (talk) 15:33, 9 June 2011 (UTC)

Yes, the lithium-air battery would have to gain weight as it discharges, much as iron gains weight as it rusts. Lithium-air batteries would still be lighter on average than batteries that carry their own oxidizers at all times, because even with all else being equal, the batteries in a vehicle would spend most of their time being only partially discharged, and this could be minimized with frequent recharging. But all else is not equal; Li-ion batteries use oxidizer chemicals that are heavier than pure oxygen.

Recharging the battery would produce oxygen gas, which would either discharge to the atmosphere, or could possibly be collected and used separately or sold as a commercial product. See Oxygen#Industrial production - the annual market for oxygen extracted from air is 100 million tonnes. Perhaps fleet users of battery-powered delivery vehicles would recharge them at central garages, producing enough oxygen to be worth collecting. Disclaimer: I have no idea whether collecting the oxygen from recharging Li-air batteries would be economical, but I'm sure someone would have thought to try. --Teratornis (talk) 18:13, 6 May 2012 (UTC)

Avoid expressions that date quickly

See WP:DATED. The article contains some references to time that violate this guideline (such as "currently"). --Teratornis (talk) 18:17, 6 May 2012 (UTC)

The energy density of gasoline ..

Article: "The energy density of gasoline is approximately 13 kW·h/kg, which corresponds to 1.7 kW·h/kg of energy provided to the wheels after losses" - A mere 13% of the energy being delivered to the wheels is an astounding inefficiency so, although gasoline is not the topic of the article, links and references to this datum and idea would be useful. 2.98.251.179 (talk) 15:57, 4 July 2013 (UTC)

The relation to the commonly known energy container gasoline (I would prefere diesel or cerosine) is very useful and spectacular. I use to do so for batteries or hydrogene storage. But even if there is a reference for it, 13% total efficiency was state of the art for cars ("to the wheels") in the 1930s or for present U.S.-American tanks. Probably the reference is obsolet or not competent for combustion engienes. For present German cars (BMW, VW, Audi, Mercedes, Porsche) is a total fuel efficiency of 40% the minimal standard. It is not mentioned what is included in the "losses" but for 13% the energy expense for construction, maintainance and wrecking of the car seem to be in (by theories of some ecologic activists). Calculated that way even solar cells, wind generators and nuclear power plants are energy sinks...--46.115.87.169 (talk) 07:41, 14 July 2013 (UTC)

Unclear wording in Challenges section

The last sentence of the second paragraph of the "Electrochemical" subheading of the "Challenges" section is not a sentence: "The mechanism of improvement, but may alter the structure of the oxide deposits.[31][32]" I would propose a change but I'm not entirely certain what the point of this sentence is. Any thoughts? Eddill (talk) 17:29, 31 December 2013 (UTC)

Check the wording in the Operation section

Quote: "lithium is oxidized at the anode forming lithium ions and electrons". Why does it say "oxidized at the anode"? Surely "forming lithium ions and electrons" means "ionisation" not "oxidisation". From what I understood, lithium atoms are "ionised" at the anode, then travel to cathode to be combined with oxygen (thus being oxidised at the cathode). — Preceding unsigned comment added by 69.67.167.78 (talk) 19:17, 31 July 2014 (UTC)

Just to clarify this electrode situation: cathode is always negative, anode is always positive. Lithium or other metals in a battery are called cations, they wander to the cathode during electrolysis, or only interact as the negative cathode during battery operation, and oxygen/oxide and chlorine/chloride or even sulfate or hydroxide are called anions, and they only interact with the positive anode, during electrolysis/charging or battery function/discharge .

In normal battery discharging and electric energy providing operation lithium metal, a strong reducing agent, is oxidized at the cathode to positive lithium ions or cations via electrons it gives off, or pressurizes to large negative voltage, that get sent to the other electrode, while oxygen, a strong oxidizer, is reduced at its electrode, the anode, into negative oxygen ions or anions by the electrons it receives from the other electrode, or via the positive suction it provides to these electrons at its positive anode.

(All voltages being positive electron suction or negative electron pressure vs. a reference voltage, just like altitude up a mountain side is in reference to sea level or a town down the valley, but there is no such thing as absolute height nor absolute voltage. Sea level and the hydrogen electrode are usual references, even if not the most practical in most measurements, and the Calomel electrode or saturated silver chloride/potassium chloride electrodes are usually the practical reference electrodes in pH meters or practical electrochemistry, at reference voltage different from the standard 0.0000.. V of the platinized platinum surface gas bubbled hydrogen electrode.)

In battery charging or electrolysis operations the reverse process happens: electric energy is fed into the system, and converted into stored chemical energy. The reactions of the cations and anions still happen at their same electrode, cathode or anode, but they are reverse. In charging, lithium, a strong reducing agent, is this time reduced by even stronger reducing agent electricity electrons received from a windmill dynamo or solar cell into zero valent neutral elemental lithium metal from the positive lithium dissolved cations in solution at the cathode. (These dissolved positive cations do nothing at the positive anode, as they are already at max charge, however if it were possible to create a Li++ two valent ion with ease, then there could be interaction of oxidation, or receiving an electron from Li++ to Li+, and you could call Li++ a positive cation with respect to the more negative Li+ anion. But such things, which may be possible in a bend over backwards theoretical way, do not happen in practice due to the enormous energy requirements that would rip all water and the glass container molecules apart way before they do occur.) So to get back, in the reverse, chemical energy storing, electrolysis or battery charging operation, oxygen, a strong oxidizer, is in turn itself oxidized by an even stronger oxidizer positive charge, or electron suction force received at the anode, and turns into a neutral, zero valent, elemental oxygen gas molecule. Sillybilly (talk) 16:33, 7 January 2015 (UTC)

To recapitulate, anode is always positive, cathode is always negative. Metals like lithium or iron are reducing agents that are cations, always at the cathode whether discharging or charging, whether reduced or oxidized, while nonmetals like oxygen or chlorine are oxidizing agents that are anions. It's not that complicated.

Well, you can have silver or gold as metals that are very noble and oxidize very difficultly, and themselves can be used as oxidizers for lithium or iron, on a relative basis, but in their compounds like silver oxide or gold oxide, they still carry a positive charge, and are still called cations. I have not heard of such a thing as lithium goldide where gold would act as an anion carrying a negative charge that interacts with a positive anode. Semimetals can vary, such as phophorous, arsenic, antimony and bismuth, which have metallic tendencies, and nonmetalic ones, and phosphorous can be an anion in a phosphide like Li3P with a -3 anion valence charge, or cation in P2O3, with a + 3 cation valence charge, or P2O5, with a +5 cation valence charge, which is up for debate in case of phosphorous oxide on covalent bond shared electrong arguments, but less debatable for bismuth oxide Bi2O3, where the bonds are more polarized and more ionic in nature. Sillybilly (talk) 16:33, 7 January 2015 (UTC)