Carbon nanotube spring batteries are a technology waiting for mass nanotube forest growth methods to become consistent enough that there are no major defects lowering their combined tensile strength. They have the potential for an energy density ten times that of the best current rechargeable batteries. Unlike current batteries, and even upcoming batteries like lithium nanowire batteries with the same potential tenfold increase, they can also have flexible and amazing power density, can be cycled infinitely without wearing out, are insensitive to environmental factors like temperature, can store energy indefinitely without leakage, and are probably more environmentally friendly (another debate?).

 

So, I guess the major questions I have here are:

 

1. When do you think carbon nanotube forest generation will become consistent in making the same type of nanotube without defects?

 

2. What about graphene? I think graphene, as a thin sheet, is prone to bending with temperature changes.

 

3. Could energy density be increased by interlocking nanotubes or graphene sheets? That's probably impossible though - I don't know.

 

4. What kind of technology would become feasible with this increase in energy and power density, durability, longevity, and environmental insensitivity?

 

I'll add to number four - transportation and unmanned aerial vehicles seem like the coolest and most pressing applications to me. Maybe some energy collection methods aren't feasible without some kind of intermediate storage?

 

This is the best article I can find about CNT spring batteries: http://memagazine.as...SuperSpring.cfm.

It's always the same story with nanotube strength. When you take a narrow filament, it's incredibly strong - be it a carbon nanotube, a steel whisker or a polyester fibre. But as soon as we put many of them together to make a rope or some part of usable size, strength has nothing to do with the observations at microscopic scale.

 

As for the many supposed advantages of a spring made of nanotubes: this is sheer speculation. Until a several thousand have been built and tested, we completely ignore how they behave. Forecasting their performance is completely out of reach of any kind of science.

 

And for the applications: nobody knows neither. Partly because we ignore the performance sizeable parts will have, partly because a single person cannot invent many uses, less so invent both a material and its uses.