In Stores Soon: Graphene-Enhanced Li-ion Batteries That Charge In Minutes | Popular Science

[Mike O'Dell]

Achievable charge rate has to do with current collector resistance,
ion mobility of the primary reaction, the rate of any secondary side 
reactions
(especially if they evolve gas like hydrogen or even oxygen),
depth of discharge, and how many times you want to (re)charge.

NiCads are famous for insanely high charge rates in special applications.
the NiCads in "smart" artillery shells can be charged in milliseconds 
using a BIG,
(comparatively) high-voltage capacitor bank to produce spectacular 
charge currents.
They can get away with this because it only has to charge *ONCE*.

Graphene is the current darling because of its directional conductivity 
(in-plane
conductivity is high, between planes is low) should work great for 
current collectors
which take up little volume or mass, and in some cases, can serve as a 
surface
catalyst for some reactions.

The issue with all of these, however, is that the leap from theory to 
bench reaction
is usually not worse than 10x, from bench reaction to hand-made "pouch 
cell" is
another 10x, pouch cell to prismatic or cylindrical engineering 
prototype is another
10x, from engineering prototype to manufacturing first test article is 
another 10x,
and from first article to volume production is yet another 10x.

anywhere along this exponentially rising hill-climb can be the show-stopper.
it can be fundamental technology (eg, secondary reactions that get out 
of hand
as scale increases), materials economics (eg, of graphene doesn't go 
down with
production volume like is expected), manufacturing processes (eg, 
fabrication
process is not repeatable or requires complex procedures or equipment that
wreck the economics), device yield never hits the value required to hit the
cost curve, and on and on.

scaling these industrial production processes is *really* hard. One of 
my partners
at the day job has a PhD in materials from UCSB and after he finished, 
he worked
at Raychem where he worked on getting the self-resetting polymer "fuse" into
volume manufacturing. the device they ended up shipping was surprisingly 
different
from the device they started trying to produce, precisely because of the 
materials
and process problems, and the economics required by the would-be customers.

     -mo


On 6/24/13 8:44 PM, Joseph Bento wrote:
> 'Trons are not free.  Depleted energy has to be replaced, generally at 
> a slightly higher rate than what was consumed.
>
> Take a 90 watt-hour laptop battery as an example.  That's somewhere 
> around 5AH.  I seriously doubt, for example, one is going to pump 10 
> amps or more for 1/2 hour to charge this battery back to capacity.
>
> Plus, you'd be dealing with some rather large conductors to accomplish 
> this feat.
>
> Joe, N6DGY
>
>
> On 6/24/2013 1:41 PM, Andre Kesteloot wrote:
>> http://m.popsci.com/gadgets/article/2010-07/coming-soon-graphene-enhanced-li-ion-batteries-charge-your-gadgets-minutes?cmpid=obinsite 
>>
>>
>>
>> Sent from my iPhone
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