Toshiba Boosts Energy Density of Li-ion Battery by 50%

Thought some of you might find this interesting:

The company improved the energy density by about 1.5 times by replacing lithium cobaltate previously used for the positive electrode, it said.

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http://techon.nikkeibp.co.jp/english/NEWS_EN/20090415/168781/

Very interesting....Hope the manufacturers of the batteries that we use for flashlights use these advancements in the near future.

They only have 2.4 Volts.... that's a pity :shakehead

Timmo.

i can't read the link, but from what other mention that the new cell only produce 2.4v i am really not that optimistic.

lets do the calculation shall we...

lets assume a standard 18650 3.7v has 2000mah in capacity, toshiba claims that they can boost the capacity by 50% which is 3000mah for the same battery dimension but 2.4v.

now the math.

3.7v * 2Ah = 7.4Wh
2.4v * 3Ah = 7.2Wh (Toshiba Battery)

well i dont see the improvement there unless there are something that i am missed

Energy Density is defined as total energy per unit volume.
But as you inadvertently pointed out, Watt Hours is the appropriate measure for total output, and Amp Hours is just one component of the calculation.

Relative to your 18650 example of 7.4Wh (2000mAh @ 3.7v) this new cell would have a total capacity of 11.1Wh (4625mAh @ 2.4v) in the same volume. That would be a total energy density increase of 50%.

I would happily adapt a new light design around 6S of these cells! That would be entirely bad@ss actually! I could only hope that they would be released in some common form factor that we can easily use.

ps... I can't see the link either.

It wouldn't bother me to use cells at 2.4V. I can actually see some benefit.
One of the things I've found aggravating is when you have strict voltage range for this or that light, electronic device etc, the higher voltage LiIon cells make it much more difficult.
For example, I have a ballast that takes between 11 and 14.8V. 3 LiIon in series gives 12.6 fresh off the charger and settles to 10.8V rather quickly making them mostly useless. And 4 LiIon cells has a peak hot off the charger voltage of 16.8V which is definitely a bit too much for my comfort, even considering voltage sag under load. But with 5 or 6 2.4v cells, depending on peak charging and working voltage, I may be able to get them to work. (luckily LiFePo4 works for me in that setup currently)

OK, here's a calculation.

Let's suppose a regular 18650 has a nominal capacity of 2000 mAh at 3.7 V. That would give an energy of 7.4 Wh as has been noted.

Now the volume of an 18650 is approximately 18² x pi/4 x 65 = 16 540 mm³

According to the referenced article, the new cell has a capacity of 4200 mAh at a nominal 2.4 V, with dimensions of 62 x 95 x 13 mm = 76 570 mm³

If we adjust the capacity for the volume of an 18650 we get an equivalent of 4200 x 16540 / 76570 = 900 mAh. So this chemistry in the 18650 format would have an energy of 900 mAh x 2.4 V = 2.2 Wh.

So unless I'm missing something, the energy density is much lower than a regular 18650 cell. I suspect apples are not being compared with oranges here, and that the kind of prismatic cells being talked about for heavy duty applications have an entirely different construction and mode of use than regular cylindrical Li-ion cells.

NeSSuS-GTE said:

Energy Density is defined as total energy per unit volume.

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thanks for pointing that out i should've read the title more carefully