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Hybrid batteries being a combination of super capacitor and battery offer what will be the ideal solution for cars, especially in stop and go driving. The speed of charge and discharge of a super capacitor are not only an ideal solution for short term storage with the a very high rate of absorbing and discharging energy using inexpensive materials, but also take major wear and tear off the main batteries, extending their life considerably. Just like advances in batteries, it will be interesting to see the advances in super capacitors and how the two will be integrated in the future. It will also be interesting if a single set of standards for hybrid batteries comes out, making working on designs incorporating them easier and more economic to use if they become widespread. Another question is if these will end up getting used at the nanotech level or at least in very small devices. It isn't hard to see a range of specialized uses where super caps and hybrid batteries offer ideal solutions to a myriad of challenges.[FONT=Theinhardt, Helvetica, sans-serif]Ultra-capacitor hybrid radically boosts power and efficiency of lithium batteries[/FONT]
Produits - NAWA Technologies
Actual product has 15 Wh / kg which is around 8% of what Li battery systems (whole systems, including structure, cooling, and control) can hold. As Tesla shows, there is really no problem in power density (too damn fast as it is) and they can supercharge effortlessly at 150kW if they want and not damage the batteries. Or maybe not, maybe the reason braking is not so extreme is that the instantaneous charging on deceleration is not as good as the well controlled supercharger. So, there might be some use for a supercap in buffering that situation. Let's say you want to come to a complete stop at 200kW (270 hp) in 3.6 seconds entirely with regeneration, but not put that straight into the battery. So that would be around 1/1000th of an hour, 200,000 W, or about 200Wh. Allowing some excess for not running the supercap completely flat (it is hard to run high power over too large a voltage range) that might be 20kg of supercap, and add another 5kg of structure and controls.
Or you could add another 5kWh to the main battery for that weight. My observation is I rarely regenerate on the model S beyond the limit (around 50kW of regen, about 70hp) so I doubt that supercap would make enough difference to range to be worth it. Makes sense for leadfoot applications like racing cars, but probably just added complexity and weight on a normal vehicle.
A supercap could become important if some other kind of battery with superior energy density had less power density. Could. At the moment the trend seems the other way, the robust and durable formulations are also proving pretty good at delivering and accepting power. Seems likely that is correlated to superior cycle count.
Only if the control circuitry is letting transients in. So long as the control keeps it within safe limits there should be no wear. As I noted, there may be desirable future chemistries where the rate of recharge is seriously limited but the currently dominant EV batteries seem to have high charge limits.
There have been some surveys of long term battery life for Tesla. Oddly, outliers on the good side included some limo companies who almost exclusively use supercharging. The high speed charging, much faster than the regenerative system, seems to have no ill effects. Now, there are other EVs with battery life not looking as good as Tesla, including some leading versions in China. Not clear if the better answer there would be wrapping them in supercaps, or cleaning up the chemistry and the regulation electronics.
The technology behind super caps should improve dramatically, just like all technologies. It seems a combination of capacitors and batteries of different types of both might be the best combination.
