

Study Finds a Way to Prevent Fires in Next-Generation Lithium Batteries - DenisM
https://www6.slac.stanford.edu/news/2015-06-17-study-finds-way-prevent-fires-next-generation-lithium-batteries.aspx

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DenisM
This seems like a really big deal. Two important quotes:

 _The findings [...] could help remove a major barrier to developing lithium-
sulfur and lithium-air batteries, promising future technologies that could
store up to 10 times more energy per weight than batteries now used in
consumer electronics and electric cars_

 _In tests, batteries with both chemicals added operated at 99 percent
efficiency after more than 300 charge-discharge cycles, compared to
significantly decreased efficiency after 150 cycles for batteries treated with
lithium nitrate alone_

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heimatau
I wonder if Tesla's patents helped with this. If not, I look forward to when
someone takes both innovations and creates something world changing like
enduring and safe batteries.

------
contingencies
Good for mobile applications. For fixed location (eg. renewable energy for
off-grid housing) I'm still keen to see the performance of Velkess flywheels:
[https://www.kickstarter.com/projects/1340066560/velkess-
ener...](https://www.kickstarter.com/projects/1340066560/velkess-energy-
storage) which, being kinetic and held in vacuum, nominally don't wear out for
a very long time and provide other benefits (reduce losses due to AC/DC
conversion).

~~~
ChuckMcM
Interesting web site, (velkess) but I worry about the lack of actual
information. The "A" version
([http://www.velkess.com/products/#VelkessA](http://www.velkess.com/products/#VelkessA))
for example, 750 lbs, 15kwH seems like it would have to be spinning quite
rapidly in order to avoid provide that energy, and making bearings that can
carry that load and work reliably is pretty tough. I look forward to reading
reviews of their products though, flywheel type systems have been successfully
deployed in many places, one at this price point would make for an interesting
midpoint between grid tied and full off grid solar.

~~~
contingencies
I'm no civil engineer but the info on their kickstarter is more engineering-
oriented. I don't vouch for them, I just think they seem pretty legit and
interesting. Obviously, the "it can't move" and "it's damn heavy" factors make
it useless for the majority of applications, but for off-grid renewable energy
purposes it does seem ideal.

~~~
ChuckMcM
Oh absolutely, we had what it nominally referred to as a 'motor-generator' set
in the basement of the building where I worked to provide backup power for the
machine room. It worked by using regular AC power to spin a flywheel which was
then spinning a generator through a continuously variable transmission (CVT).
If the power failed, and you did your math right [1], the flywheel's momentum
would continue to keep the generator going for another couple of seconds
before power actually shut off. During those two seconds though the computers
would know that power was "off" and to do the appropriate things to be ready
for that (like park the heads on the drives, unload vacuum column tape drives,
shutdown the drum, etc etc.) All stuff you could do in 100 - 250mS which saved
a lot of work later on.

The engineering challenges though were size (it ended up being this horizontal
thing that filled the room). Keeping it sealed with a vacuum (if there was air
in the flywheel chamber it adds drag to the wheel which robs you of energy),
and dealing with its very strong desire to precess if the ground moved in any
way. The engineer responsible for its installation suggested that if there was
6" of ground movement in an earth quake the gyroscope effect would wrench the
flywheel off its mount and it would rapidly climb out of the basement on its
own momentum. (something I was secretly desiring to see in action)

[1] The first one they installed they did the calculations incorrectly and
when they tested it the flywheel stopped in just under 10mS with a very loud
bang. Fortunately you can boost energy storage by increasing mass and/or
increasing RPM which they did (both off) and got it to a sustain duration of
1800mS (not quite 2 seconds worst case)

