Nanostructured Li-ion Batteries for Electric Cars

schliz writes "Researchers at the Delft University of Technology are developing nanostructured batteries that are expected to deliver more usage between charges, and shorter charge/discharge times, to mobile consumers within the next five years. The batteries will improve electric and hybrid vehicles, researchers say."

Comments

Re:What's wrong with...

[Anonymous Coward]

Lead-acid batteries are a lot worse in comparison...

Lead-acid batteries
Energy/weight 30-40 Wh/kg
Energy/size 60-75 Wh/L
Power/weight 180 W/kg
Charge/discharge efficiency 70%-92%
Energy/consumer-price 7(sld)-18(fld) Wh/US$ [1]
Self-discharge rate 3%-20%/month [2]
Time durability 6 months
Cycle durability 500-800 cycles
Nominal Cell Voltage 2.0 V

Lithium-ion batteries
Energy/weight 160 Wh/kg
Energy/size 270 Wh/L
Power/weight 1800 W/kg
Charge/discharge efficiency 99.9%[1]
Energy/consumer-price 2.8 Wh/US$
Self-discharge rate 5%-10%/month
Time durability (24-36) months
Cycle durability 1200 cycles
Nominal Cell Voltage 3.6 V

Several things

[Flying pig]

The main benefit of lead acid batteries is that they are cheap to make and easy to recycle. However, they do not have very good energy density. A 110AH lead acid battery weighs about 30kg and cannot be repetitively discharged below about 70% of capacity without a severe reduction in life. At 50% discharge you are down to maybe 100 charge/discharge cycles, go very far below that and you will rapidly destroy the battery. The AH rating is about as meaningful as those "200HP" engines in US cars that turn out to have an SAE rating of 55HP.
Effectively it is about a 35AH battery with a total energy delivery of 12V * 35AH = 420WH. The equivalent LiIon batteries would weigh, I guess, around 4kg with packaging. As a result, lead acid batteries are unsuited to any automotive use except those where they can substitute for ballast, such as boats and powered wheelchairs where the batteries help lower the centre of gravity.

Quite a lot of research has gone into the lead/peroxide cycle, especially given the constant desire to make them smaller and more reliable. It hasn't been hugely successful. You can have high discharge rates and long life at the expense of much more weight and much higher cost, but the nature of the cycle itself (the production and destruction of large amounts of lead peroxide) makes it hard to design a system that can handle many charge/discharge cycles without very large and heavy storage arrays.

Re:The first of many stories

[KnightMB]

No more maintenance that any other battery. If you want to get some feedback from people that are already using these, check out this electric vehicle forum. http://endless-sphere.com/forums/ I think they are already ahead of what most think is possible with electric vehicle transportation.

Re:The first of many stories

[fyngyrz]

They [ultracaps] certainly don't have the energy density of batteries

Actually, they're getting very close, and right now, there are projects projecting power densities three orders of magnitude higher than batteries, in the 100 KW/kg range. So I don't think the current state of affairs (batteries > ultracaps) is going to obtain for very much longer.

and the largest problem with them is that the discharge from an ultra-capacitor is hard to deal with using normal electronics. It can be compensated for, but it isn't easy.

What? ultracaps have the same discharge curve as any capacitor does; the voltage drops very smoothly as the energy in the cap is dispensed. "Dealing with it" is nothing tricky at all, the technology has been in place for this for literally decades. Modern switching power supplies are *very* efficient at creating constant voltage outputs from all manner of raggedy inputs across a wide range of input voltages, if and when required. They can be engineered to be reliable and very long lasting. This is simply a non-problem. Also, ultracaps can absorb energy (for example, from regenerative braking) at a much higher rate, leading to less wasted energy. We have all manner of high-current switching devices with such low on-resistances these days as to be utterly amazing to an old-timer like me.

I also don't buy the "environmentally friendly" nature of them as well. While they may be better than NiCd batteries or the more traditional Lead-H2SO4 batteries in terms of what they will do to the environment, you can't call them a perfect solution either. The metals used in the construction of these types of capacitors have their own kind of impact on the environment just like any manufactured product.

You're just hand-waving here. Recycling is one issue, toxicity is another, corrosion is another, and all of them are far less critical for ultracaps - not to mention that the lifetime of an ultracap is so much longer (up to a quarter of a milling charge/discharge cycles, or more) than that of a battery, so it is that much more seldom that recycling becomes an issue. It really isn't reasonable to say that ultracaps pose the same kind of environmental issues that batteries do. They don't. Perfect? No. But what is?

If a "Moore's Law" were to apply to battery capacity, instead of the (presumed) 18 month half-life of procesor density and speed, it will be more like 15-20 years instead for improved energy density.

Yes, but (a) ultracaps aren't batteries at all, and (b) ultracaps are increasing in capacity at a prodigious rate, where batteries are not. Mind you, they're coming from behind, but they're a brand new technology with tons of new research driving the improvements, while batteries are not new and many, many avenues have been tried and abandoned for increasing battery capacity for exactly the reason you cite: It is hard to improve the current battery designs.