Tom Cheesewright on The biggest failing of gadgets today is their power source: the battery. Though battery technology has advanced in the recent past, it hasn’t kept pace with increasingly powerful and power-hungry processors, screens and wireless communications. The result? We are tied to our chargers.
This is about to change. For the last few years nanotechnology has been big news in the battery world. It has already had some impact and there is plenty more to come.
Nano-what?
Nanotechnology is engineering on a very small scale: less than 100 nanometres (where one nanometre is one billionth of a metre). Working at this scale means assembling structures out of individual atoms. But this isn’t like building in the ‘big’ world: at nano scales the laws of physics are different. Materials behave differently, and all manner of strange ‘quantum’ effects can be observed.
As far as batteries are concerned, nanotechnology is being applied to a number of challenges: how much can the battery store? How fast can it be recharged, and how many times? Does the charge leak away when it is not in use?
The Hourglass Analogy
To understand these challenges you have to understand the basics of how a battery works. It’s not a perfect analogy, but here’s how I imagine it.
Think of an hourglass — the ones with grains of sand sealed inside a glass tube that narrows at the middle. The sand in this case represents charged particles known as ions. Charging the battery is like tipping it on one end. All of the charged particles go to one side. Discharging it is like flipping it over: all of the charged particles flow to the other side.
When all of the charged particles are at the ‘charged’ end of the hourglass, there is ‘potential’. In our hourglass this ‘potential’ is for movement: turn it over and the grains will flow down. In our battery this potential is electric: connect the two ends of the battery to a load (e.g. your phone) and the charge will flow from one end to the other, powering whatever is in the middle.
Make sense?
Leaky Batteries and Limited Capacity
Now hourglasses have a problem: if you turn them upside down, or even sideways, the sand starts to flow. Even if you’re not ready to start timing.
Batteries have the same issue: once they are charged, the potential is so strong that the charged particles can start to be pulled back to the uncharged end as soon as the charger is disconnected. Nanotechnology is being used to create a smart ‘valve’ layer that stops charge moving unless there is a need for it, prolonging battery life.
Now imagine you want your hourglass to run for two hours, or three, or four. How would you need to change the design?
Firstly you would need a lot more sand in there. But then you have the problem that moving all that sand to the ‘charged’ end would take as long as timing the thing you want to time. So you would need the sand to move really quickly to the charged end, then much more steadily back.
Nanotechnology is helping here too. When you have lots of capacity it has historically taken a long time to charge a battery because the charged particles take time to move around — just like the sand. Nanotechnology is providing us with high capacity structures for the insides of batteries, like a very, very fine honeycomb. This is combined with very fast flowing routes to get the charged particles to their location. The result is batteries that can store more charge and still charge very quickly. It is estimated that phones could charge in a matter of seconds, cars in just a couple of minutes. Fortunately, charged particles are a lot smaller than grains of sand (roughly a million times smaller), so high capacity nanotech batteries don’t have to be much larger.
These changes, combined with new materials and smarter manufacturing techniques will see batteries change dramatically over the next five years. I believe, and hope, that we will see gadgets with batteries lasting weeks not hours, that charge rapidly, and more than likely, wirelessly.
Want to read more? Here’s a few interesting sources on nanotech batteries:
http://www.wired.co.uk/news/archive/2011-03/21/3d-nano-batteries
http://www.sciencedaily.com/releases/2009/03/090320173859.htm
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This article is by Tom Cheesewright. This post forms part of the Future of Cities series. For more posts on this subject, visit the Future of Cities page.
