Dylan Smith wrote:
On 2012-12-31, wrote:

As for "emerging technology", the lithium battery was invented in 1912.

The lithium battery of 1912 shares nothing in common with the lithium-ion
battery of today apart from the use of lithium. That's like saying
the transistor was invented in 1947, so therefore semiconductors are
not going to change or improve.

The Li-Ion battery wasn't actually invented until 1979 and bears no
resemblence to the lithium-ion battery or lithium-polymer-ion battery
(indeed, the particular chemistry for Li-Ion wasn't discovered until
the 1970s). The term "lithium battery" refers to many different battery
chemistries which generally are not alike, except they use Li. Anode
and cathode technology is a hotbed of development, and when it comes
to energy density, the anode and cathode structure is enormously
important.

Li-Ion and Li-Poly has significantly improved just over the last few
years, since I started fiddling with RC helicopters 5 years ago, the
batteries have improved noticably, they've got a bit smaller, the "C"
ratings (the maximum discharge rate) has gone up significantly, and
also the maximum charge rate has significantly increased. And the cost
has gone down, too.

If by "the last few years" you mean around 2004 when the last incremental,
not order of magnitude, improvement to lithium-ion batteries was made,
then I agree.

A couple of orders of magnitude of improvement are needed to make things
like general purpose, e.g. C-172 equivelant, electric airplanes practical.

As for the batteries for RC helicopters, this has more to do with the
market becoming significant than much of anything else.