Today's batteries are weak, expensive and explosive.
Researchers are working on new power packs that will change our mobile world.
The future will bring us batteries that charge in seconds and offer 20 times
more performance than anything available today
A few years ago the battery world was doing
well. Mobile phones had to be charged only once a week, and simple AAA
batteries from the supermarket were enough for MP3 players. Electric cars had
awful performance, but they weren't supposed to be taken seriously anyway.
Today, however, a smartphone battery lasting through just one day is a rare
joy. The distance an electric car can run is theoretically the same as a
petrol-driven car with a full tank, but in the real world it doesn't achieve
this.
Manufacturers and researchers seem to have
reached a dead end when it comes to batteries. Mobile devices are developing
rapidly, whereas the battery technology can no longer keep in pace with it.
While CPUs and GPUs can be made more power efficient by miniaturising their
components, battery developers have a very basic problem: the material today
has reached its technological limits. Lithium ion batteries last slightly
longer than previous generations used to, but they require more space and are
also expensive.
Researchers worldwide are asking the same
questions: is optimising the available technology enough? Do we need new
architectures, or do we have to develop a special type of battery for every
different device? Different people have adopted different approaches to this
problem. Some of them are experimenting with cheap materials; others with new
configurations, higher capacities and shorter charging times. We present a
roundup of the latest and most promising technologies from laboratories around
the world.
Charging Batteries in Seconds
Batteries require much more space in
comparison to the other components of a device, be it heavy-duty unit in an
E-car or a tiny sliver designed especially for smartphones. Unfortunately, a
lot of space is left unused inside the batteries. That's why many universities
and manufacturers are carrying out research for optimising regular lithium ion
batteries to increase their performance density, which could happen quite
quickly.
The basic principle of the battery is quite
easy: Lithium ions move to and fro through an electrolyte between two
electrodes, for instance while discharging, from the anode to the cathode.
While doing so, the lithium atoms emit electrons. Voltage is finally generated
through this electron flow. One of the problems in this process is that only
one electron at most is transferred per lithium atom. The idea here is to
exploit more electrons per metal atom. The researchers are following two
approaches here: they want to increase the capacity and accelerate the charging
current. Many projects are being directed towards this research.
Researchers at Northwestern University in
Illinois, USA have developed a silicon anode that performs better than a
conventional battery by a factor of 10. In another project, researchers of the
university presented a battery that does not offer more performance but gets
charged in 10 seconds—without the capacity being affected. A mobile phone would
thus need to be plugged in for just a short while and its battery would last
the whole day. The combination of both technologies would mean a charging time
of less than 2 minutes and talktime of up to 100 hours—mobile phone owners
would be saved the hassle of always carrying along a charger.
A very porous material is required to
transfer the higher bit density into the battery in such a short time. The
researchers are now working on a cathode with a three-dimensional and
nanostructure. For that, polystyrene spheres are together with nickel. The
polystyrene evaporates and leaves behind a type of porous nickel sponge whose
holes are enlarged by "electro polishing" and then coated with
electrolytic material.
Almost as Powerful as Petroluem
The researchers under Dr. Maximilian
Fichtner at the Institute for Nanotechnology of the Karlsruhe Institute for
Technology (KIT) are working on optimising lithium ion batteries. Dr. Fichtner
explains the principle: "Our system is based on iron that is encapsulated
as iron nanoparticles fixed in a carbon shell, and which has a reaction with
lithium fluoride. This generates iron fluoride and lithium which can be saved
in the anode". At the moment, batteries can be improved upon by a factor
of two —but the goal is to have a battery that exceeds conventional ones by at
least five times.
For electric cars, this would still be
insufficient. A clear leap in performance would require much more than
developing current technologies further. New architectures must be created for
such heavy use. Another concept from the Karlsruhe researchers is a type of
battery in which fluoride ions are used instead of lithium. For that, they are
using metal on the anode and metal fluoride on the cathode. The big advantage
of these materials, according to researchers, is that an energy density of up
to 5,000 Wh/I (Watt hours per liter) can definitely be reached. In comparison,
petrol has an energy density of about 9,000 Wh/I whereas lithium ion batteries
only offer a mere 25 Wh/I. It will take several more years before we see
fluoride ion batteries in the market. "The design has not been finalised
yet. We are still researching it," says Dr. Fichtner.
Cheap and Safe Batteries Becoming the Norm
Researchers at British Leeds University are
dealing with another problem: current-day batteries are expensive to
manufacture, and thus are expensive in market. Besides that, they are also
sometimes dangerous, in that they short circuit, catch fire, or even explode
due to heat or shock.
The researchers could overcome both
weaknesses with their new gel battery: up to 70 percent of the structure of
these batteries is made up of flowing electrolytes that are formed with polymer
into a jelly-like mass. These batteries are not combustible and are also
cheaper due to a relatively simple and fully automatic production process: the
gel is simply pressed between the anode and the cathode and shaped into a foil.
Another advantage of the gel battery is its
flexibility: it can be cut and folded into any size. In contrast to
conventional batteries, the gel battery can also adapt quickly to a specific
device like a thin layer behind an LCD screen or a sheet under a notebook
keyboard. Unfortunately, the gel battery concept does not have much more power
than existing lithium ion batteries. Apart from that, there is nothing stopping
these batteries from entering the market in smartphones and other gadgets in
the near future.
