Battery technology is an active area of research, but an obvious question occurs to me: why is it, no one has determined the maximum possible energy/volume, and energy/weight? And from there, discover the chemistry which achieves it?
Is there some lacuna in our understanding of solid state physics which necessitates an empirical, rather than theoretical approach?
-- Rich
I believe it has been done. The ultimate limit is pretty much defined by the electromotive series. After selecting your electrode materials you should know the THEORETICAL potential difference available for that cell. You know that you get one mole of charge per equivalents of each of anode and cathode materials. That gives you an upper limit energy output for the a known mass of electrodes. Throw in the mass of require electrolyte and structural material. That gives you the scientific limit. Then it becomes an non-trivial engineering job.
Other technological problems arise on suitable redox reactions. My first hand experience is limited, but it seems hat lithium based anodes will give just about the highest energy density because of the high electropositive nature of lithium and lithium's low atomic mass. Life is complicated because aqueous electrolyte of olde primary cells is not suitable for lithium anodes.
It is this kind of engineefing that will affect ultimate performance.
Bill
-- An old man would be better off never having been born.
Ya gotta reduce to practice, it must recharge at least 1000 times; exploding during storage, use, or recharge is a bad thing.
1) Aluminum / fluorine battery is great gazongas on paper - dig the equivalent weights; 2) tetrafluorotetracyanoquinodimethane / 1,3,6,8-tetrakis(dimethylamino)pyrene is great gazongas on paper. 3) Go build either one, inorganic or organic. We'll wait.-- Uncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/qz4.htm
Finding the max possible just shows you where you stand in the scheme of what is possible. That is not our problem. The problem is to be useful batteries must be useful. That means they must have a reasonably long life (unlike the so commonly used non-liquid ni-cad pieces of crap), they need to store as much energy as possible without a lot of weight (hence the differences between lead and lithium), and you don't want them to discharge by themselves as they sit around (Nickel Metal Hydride), Hence the real problem as Uncle Al notes is practicality.
Batteries are on the margin of useful presently but Lead-acid are heavy. Ni-cads tend to die in a hurry especially if charged a lot. Ni- MH tend to discharge just sitting, and Li-ion while very nice in a lot of ways, tend to slowly sink into the sunset within about 5 years. And this doesn't even get into what it costs to build these batteries.
Just doubling the life of Li-Ion batteries would go a long way toward making an electric car decent. What good would "theoretical maximum" storage do if the thing isn't practical?
Finding the max possible just shows you where you stand in the scheme of what is possible. That is not our problem. The problem is to be useful batteries must be useful. That means they must have a reasonably long life (unlike the so commonly used non-liquid ni-cad pieces of crap), they need to store as much energy as possible without a lot of weight (hence the differences between lead and lithium), and you don't want them to discharge by themselves as they sit around (Nickel Metal Hydride), Hence the real problem as Uncle Al notes is practicality.
Batteries are on the margin of useful presently but Lead-acid are heavy. Ni-cads tend to die in a hurry especially if charged a lot. Ni- MH tend to discharge just sitting, and Li-ion while very nice in a lot of ways, tend to slowly sink into the sunset within about 5 years. And this doesn't even get into what it costs to build these batteries.
Just doubling the life of Li-Ion batteries would go a long way toward making an electric car decent. What good would "theoretical maximum" storage do if the thing isn't practical? ============================================ The best way to store a lot of energy in a small, lightweight space is to use TNT, nitroglycerine or similar compounds. It is also not practical for domestic application, it has too much energy. The ideal "battery" consumes its fuel as current is drawn from it and produces its fuel as it recharges. Hence the hydrogen fuel cell. Against it is free atmospheric oxygen with which the hydrogen can combine, rendering hydrogen dangerous. What's needed is two substances which do not react in air but combine with each other to release energy, stored in two tanks. I'll leave it to you chemistry types to find the right fuel.
Probably the best all-rounder right now is LiFeP
However, I suspect that the price of Lithium is going to skyrocket. Aluminium might be a better choice in the long term. An Al/Air secondary battery would be ideal.
-- Dirk http://www.transcendence.me.uk/ - Transcendence UK http://www.blogtalkradio.com/onetribe - Occult Talk Show
You don't understand explosives. They don't have more energy than other fuels. What they have is brisance, the ability to build up pressure quickly. Gasoline, for example, has about 10 times more energy content per unit weight than TNT.
| > The best way to store a lot of energy in a small, lightweight space | > is to use TNT, nitroglycerine or similar compounds. It is also not | > practical for domestic application, it has too much energy. | | You don't understand explosives.
Yes I do. You don't understand energy.
| They don't have | more energy than other fuels.
Bwahahahahahahahaha! You don't understand anything, you stupid f*ck! Go away, you are a moron.
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Hey Andro! It's time to go read a freshman textbook again! Anyway we were talking here about batteries NOT fuel cells. Two different things. In batteries you charge them with electricity you don't feed them fuel like some engine.
I love it when Andro makes a fool of himself in a world-wide forum.
Yes, reaction rates matter here. A loaf of bread has more energy than the same mass of nitroglycerine
Not in a vacuum
-- Dirk http://www.transcendence.me.uk/ - Transcendence UK http://www.blogtalkradio.com/onetribe - Occult Talk Show
| >>> The best way to store a lot of energy in a small, lightweight space | >>> is to use TNT, nitroglycerine or similar compounds. It is also not | >>> practical for domestic application, it has too much energy. | >>
| > Yes, reaction rates matter here. | > A loaf of bread has more energy than the same mass of nitroglycerine | | Not in a vacuum | Thank you, Dirk. bw's suggestion for a battery, i.e. combining loaves of bread with oxygen, doesn't seem to have much merit except in animal muscle and even then it doesn't recharge. When bw can eat shit and crap loaves of bread I might be interested, but I understand that is called 'wheat'.
energy/volume and energy/weight limits are quite defined, problem is that design of battery involves not only chemistry, but also physics . i.e. take plain lead acid battery. it seems ideal from economy standpoint - it is assembled out of readily available substances (cheap). problem is it's lifetime is not very long, and it's mainly because of physical effects (diffusion, corrosion, evaporation).
same goes with lot of other designs.
You sound like you know batteries.
Do you know if any companies still make large prismatic NiHM cells, in similar form factors to the flooded aircraft started NiCd batteries?
They used to exist for electric vehicle type applictions, but this was quite some time ago. I've not seen any since.
-- http://www.google.com/#hl=en&source=hp&q=large+prismatic+nimh+cells&aq=0&aqi=m1&aql=&oq=large+prismatic+NiHM+cells&gs_rfai=CEAOJYeUfTPLTAofAzQTJ9aHfDQAAAKoEBU_QshOL&fp=bff9aea6fcd663ae
nothing relevent there.
-- Checked all 120000 results, did you? BTW, what do you mean by "flooded aicraft started NiCd batteries"?
here go over every result and tell me what you find
-- Aww... poor baby doesn't want to do her own legwork? If you're serious in your quest, I suggest you go to: http://www.concordebattery.com/dealers.php and peruse the various dealers' web sites for what you want. Johm Fields
that's a really clever idea, Johm.
I'll call up a company that only make lead acid batteries to buy giant NiMh cells.
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