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Silicon As the New Lithium
hduff writes "While lithium-ion batteries offer better performance than lead-acid or ni-cad batteries, the supply of lithium is limited and the batteries can pose problems. Researchers at the Technion-Israel Institute are building a better battery with easily obtainable sand and air."
And there is the fact that salt water has lithium. In fact, some startups are trying to extract it now. If the price goes high enough, it will be practical to extract lithium from the ocean.
Natrium is called SODIUM in English. (Not sure, but I think that English is the only language that does not use the word "natrium" for Na).
And it might not be able to form the components that you need for the battery (it's not pure lithium).
Read more here.
http://en.wikipedia.org/wiki/Lithium-ion_battery#Electrochemistry
Also, if it would work, sodium is much heavier than lithium.
First of all (I'm a researcher in power MEMS/micro power sources), I must say that a battery that has been tested for 600 hours count as an excellent proof of concept. Most of the stuff we develop we're happy if it works for minutes, let alone hundreds of hours. This is in advanced stage. Second: so what if it's "only" a primary battery? The market for primary batteries is HUGE and because they are disposable, making them cheap and environmentally friendly is just if not more important, than with secondary batteries.
"The agriculture ministry is not in charge of Gundam" - Japanese ministry official.
I have read the original publication (doi:10.1016/j.elecom.2009.08.015) and cannot understand much of the (electro-)chemistry of it.
The electrode potential is strongly dependent on the doping of the silicon, which makes sense, but the I/V curve looks less than impressive. It's mostly a bad fuel cell, at the moment.
Also, the chemistry of the electrolyte is not clear to me. In principle the battery should work according to dissolution of Si from the anode, transport through the electrolyte (an ionic liquid with fluorine) and reaction with oxygen at the air cathode. The researchers claim that they observe a white deposit at the cathode, and that this deposit is SiO2.
Silicon-fluorine chemistry is quite complicated, IIRC, and I cannot for the life of me imagine transport of Si4+ ions in the electrolyte. Also, HF as such does not dissolve Si, but it need some strong acid to start the etching. How this phenomenon can happen in the ionic liquid is beyond me.
Also, in the introduction, the researchers claim that the battery has an "infinite shelf life", but then talk about corrosion currents in the paper. If there is corrosion (i.e. self discharge), then the shelf life is quite limited.
Cherry on top, they claim that SiO2 is easily reducible to reobtain Si. I am not familiar with silicon metallurgy, but I am not sure it is easy to do it electrochemically, let alone replate Si at the anode upon recharge.
On the plus side, they used metallurgical grade Si, which is dirt cheap when compared to semiconductor grade Si.
I would love for this to work, but at the moment the authors have omitted quite a bit of information. If I were the referee, I would have asked at least the questions above. Think of it, there is a corresponding author for a reason.
Disclaimer: I work in battery research, and I am hence jealous that they made it to the front page of Slashdot.
(sorry may be some confusion - a double post since the previous one inadvertently was anonymous)
To better understand how this works, I went to the Tehnion website.
Sand is actually Silicon-dioxide (combined silicon and oxygen). Pure silicon interacts with oxygen form the air to create sand. That's first-year normal chemistry. Usually such an interaction produces heat not electricity.
They built the battery from pure silicon, and the trick is that Oxygen from the air has to pass through a membrane to get to the silicon and oxidize it. The membrane will allow only oxygen ions through, so electrons have to flow the other way to match up with the ions and maintain overall neutrality. Hence you get a current instead of only heat.
Of course it will take some years to commercialize. Small applications will come first (small batteries), only later will we get big batteries (for cars?) and even later rechargeable stuff (if at all). I noticed many people are skeptical - but this is normal in science and engineering. Any real innovation raises new questions that must be answered. Kudos to the Israeli team, and their collaborators from USA & Japan.
Aluminum is OK as a transmission medium, but it's not too good in end use applications. Turns out aluminum has a property called "cold flow", when you put it under pressure (like a screw or clamp terminal) the metal literally moves away and creates a loose connection which causes heat and often fire.
Next, greatly varying expansion/contraction properties make aluminum still more likely to work loose when terminated to a dissimilar metal like a lug or screw of brass, steel, etc..
Lastly, all aluminum has a coat of oxide that has high electrical resistance, and it reforms very quickly when it is cleaned off. Proper cleaning and antioxidant paste are critical to avoid failures in such home applications as the line dropping from the service weather head to the meter socket of a dwelling (a common application).
Once the circuits are in the walls of a dwelling you do not want aluminum because of the fire danger. While it has been used for mobile home wiring in the past during times of high copper prices, it is currently hard to insure one of those homes. If you DO have aluminum wire inside your walls you should be checking the torque (but don't over tighten) of every connection at six month intervals... forever...
To sum up, you only want aluminum where you can easily inspect and adjust any connections on a regular basis.
You have the right to remain sentient. If you give up the right to remain sentient, you will be elected to public office