Ronin of the Spirit

Because reality is beautiful.

Great News for Electric Car Aficionados

So, a kind of battery is being developed called the nanowire lithium battery.  I’m not much on electrochemistry, so I can’t tell you why having more lithium in the right place makes it work better, but I can tell you how.  The chemical relationship of silicone to lithium is such that a little bit of silicone chemically holds onto a lot of lithium.  They tried making silicone wires, but they cracked when electricity was passed through them, no small problem for a rechargeable battery.  Dr. Cui made nanowires of silicone bonded to stainless steel wire.  This gets around the cracking problem and allows 10 times more power density than is currently available from lithium-ion (li-on) cells.

He hopes it will be mass market ready by around 2013.  One likely application is electric vehicles.  I’m excited about it.  Electric cars have enourmous benefits compared to normal cars running normal engines.  Namely, mechanical simplicity.  A battery electric vehicle needs a motor, a battery pack, and a controller.  The controller is complicated at a microlevel, as it’s a large quantity of integrated circuits, but to the auto manufacturer or mechanic, it’s a just a brick.  Moving electrons beat precision moving parts every time.   Also, electric vehicles take the emissions problem from 100,000 engines built to wear out in 5 years dumping into 100,000 tail pipes and put it all into one power plant with every part designed to give the best performance dumping into one easy-to-monitor smoke stack.  

The problem with electric cars is one of energy storage.  The lithium ion nanowire battery (hereby called the Lionwire) has an energy density of 2.6 MJ per kilogram.  (Don’t know what a MJ is?  Megajoule, or 1 million joules.  Joules are a universal measure of energy that can be used to measure, heat, electricity, etc.  Handy thing to compare different energy densities because it’s universal between all types of energy.  A joule is very small, so MJ are the most convenient here.)  Anyway, the lionwire battery has 2.6 MJ/KG.  Gasoline has 46.4 MJ/KG.  

That’s not quite as bad as it looks.  A good electric car will be able to get 80% of the power that goes in down to the road.  A good gasoline engined car, 17%.  80% of 2.6 is 2.24.  17% of 46.4 is 7.89.  So, gasoline still holds 350% more energy per pound than the lionwire cell.

Well, with all the support systems for the gasoline engine out, don’t we get some extra weight allowance?  Yes.  The engine and transmission are gone, replaced by a advanced AC or DC motor.  No cooling system is needed, and no fuel system.  To actaully run this, we will need some real numbers. 

Using the example of a Ford Focus, we can remove the engine (400 lbs with alternator and oil) the transmission (135 lbs with fluid) the radiator and coolant (15 lbs) and fuel system (100 lbs)  We took 650lbs out.  We do need to put in a motor and controller.  I’ll use the Advanced DC FB1-4001A with a Curtis 1231C-8601, which has a 100HP peak rating same as the Focus OEM engine.  Unlike the OEM part, however, it weighs just 200 lbs including the electronic controller.  So we have 450lbs left over, or 204 kilograms.

The Focus has a 13.2 gallon tank, thats right around 80 lbs of gas, or 36 kg.  36kg times the post powertrain energy density of 7.89 is 284 MJ. The original energy storage of the car is 284MJ.   However, 204 kg surplus gained by removing the engine and its support systems times 2.24 is 457 MJ.  That’s gain of 160%!

That’s right, ladies and gentleman.  We finally have a battery that will yield equal or greater systemwide power densities than gas!!!  It’s not perfect, recharging still much slower than filling a tank of gas, and they will probably cost much more for awhile, but the days of the internal combustion engine car are numbered!  


November 14, 2008 - Posted by | Ecology, Engines, Microcar, Small Car, Transportation, Uncategorized | , , , , , , ,

1 Comment »

  1. The future of Electric vehicles certainly looks bright. With all the R&D that is going into EVs, batteries for these cars are getting better all the time, with lithium set to transform the EV space in much same way as it transformed the cell phone some years ago.

    Comment by Alias | November 15, 2008 | Reply

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