|Photo credit: Motorola
|Prototype direct methanol fuel cell (DMFC) battery.
DMFC may be the energy technology of tomorrow
The world’s first commercial cellular phone, also
known as the “brick phone”,
offered a half an hour of talk time, up to eight hours
of standby time, and took 10 hours to recharge.
Batteries are still the weak link in mobile devices,
but they have come a long way. The battery life of
a 3G smartphone, for example, provides more than
10 hours of 2G talk time, five hours of 3G talk time,
five hours of 3G Internet time, six hours of Wi-Fi Internet time, seven hours of video playback or
24 hours of audio playback, according to manufacturers.
These improvements allow for all-day use, and
you can leave the charger at home.
A year after the launch of the brick phone, some
300 000 people worldwide had mobile phone subscriptions.
Today, more than 25 years later, this
number has passed the 4.6 billion mark. Batteries
are critical to the usefulness of portable information
and communication technology (ICT) devices.
With ever more users going mobile, manufacturers
and governments are investing in research on clean,
energy-efficient and longer-lasting batteries to cater
for the power-hungry features of portable electronic
devices. ITU’s latest TechWatch Alert* summarizes
some of the key trends and developments in battery
technologies for mobile devices.
Advances in processing power and new-generation
communication links have increased mobility
and driven the demand for mobile phones, laptops
and other gadgets, including e-books, MP3 players
and digital cameras. Hybrid electric cars, which rely
on on-board battery packs, are the stars of many
motor shows. This was evident at the 2010 Geneva
International Motor Show, where ITU/ISO/IEC jointly
organized “The Fully Networked Car@Geneva Motor Show”, held on 3–4 March 2010.
ITU estimates that, by the end of 2010, there will
be 5 billion mobile subscriptions worldwide. Much
of this growth is taking place in the developing
world, where users often need to come up with creative
alternatives to overcome the lack of ubiquitous
power supplies. Some kiosks in rural areas not only
recharge (prepaid) units, but also batteries. Fostering
the development of batteries or devices that do not
solely depend on electric power grids for recharging,
as well as gradually improving and expanding
the energy infrastructure, are therefore essential to
connecting any user, anywhere, and to bridging the
Market research suggests that the USD 71 billion-a-year worldwide battery market (with rechargeable
batteries accounting for two-thirds) could grow by
4.8 per cent annually up to 2012.
Batteries have improved in terms of energy density,
but the higher power requirements of devices
have eaten up the benefits of better battery performance.
The net result is that runtimes stay the same.
The search is on for a safe, lightweight, small
size and environmentally friendly battery, with high
energy density, a long runtime and a long lifetime.
The breakthrough has not yet happened, but existing
technologies are being gradually improved and
adapted to meet the requirements of particular devices
There is no standardized procedure to provide
information on battery runtimes for different ICT devices.
Manufacturers and advertisers state runtimes
and lifetimes, but this information should be treated
with caution because it depends on usage patterns,
which may vary. For example, power management
settings and the use of features (Wi-Fi, DVD drive) or
applications can all affect runtimes and the lifetimes
Current battery technologies
Lithium-ion (Li-ion) and nickel-metal-hydride
(NiMH) batteries are most commonly used in portable
electronic devices. Li-ion batteries usually offer
a higher energy density than NiMH. Also, Li-ion batteries
allow for a great number of charge/discharge
cycles without memory effect, which ensures a long
battery lifetime. It is estimated that Li-ion batteries
lose up to 5 per cent of their charge per month
through self-discharge, compared to up to 30 per
cent loss per month in NiMH batteries.
Form and weight are important factors in the
choice of batteries in portable devices. Li-ion batteries
exist in a wide variety of shapes and sizes, and
are relatively light, but NiMH has advantages over
Li-ion, including lower cost, high current, and no
need for processor-controlled protection circuits.
NiMH batteries are often found in digital cameras.
Lead-acid batteries are too heavy for mobile use, and
nickel-cadmium (NiCd) batteries have been banned
for sale in the European Union because of their toxic
New energy sources for mobile devices
The need to recharge batteries compromises the
mobility and autonomy of the devices they power, so
manufacturers are searching for better technologies.
If photovoltaic and fuel cell technologies could be
miniaturized for use in portable electronic devices,
they would extend autonomy between recharges.
Fuel cells systems, in particular direct methanol fuel
cells (DMFCs), may be the energy technology of tomorrow.
Like conventional batteries, fuel cells produce
energy through an electrochemical reaction.
The main difference is that, as long as the fuel supply
lasts, fuel cells are constantly being charged.
Current DMFCs produce a low level of power, but
they can store high-energy content in a small space.
This means that they can produce a small amount
of power over a long period. This would make them
optimal for consumer goods such as mobile phones,
laptops and cameras. The main obstacles to this use
include power handling, downsizing and cost. At
present, fuel cells are generally found in environments
where no combustion is possible, and where
toxic exhausts cannot be tolerated, for example in
space vehicles and submarines.
Nanotechnology is another promising area, because
the properties of nano materials could help
in the development of high-performance Li-ion batteries.
But before being ready for use in consumer
goods, further research is required to better understand
the mechanisms of lithium storage in nano
materials, and to achieve controlled, large-scale synthesis
of nanostructures and kinetic transport on the
interface between electrode and electrolyte.
An even more recent field of research focuses on
tiny micro-batteries about half the size of a human
cell. These could be stamped onto a variety of surfaces,
and might one day power a range of miniature
devices. Nanotechnology or cell-sized battery technology
have the potential to open the way for new
features and start a new era for mobility.
Chargers and charging
When replacing a mobile phone, the user is usually
obliged also to replace its charger, which is often
not even compatible with other products from the
Unusable chargers represent unnecessary electronic
waste, as well as being inconvenient. As
part of its work on ICT and climate change, ITU’s
Telecommunication Standardization Sector (ITU–T) is
moving ahead with a technical standard for an energy-efficient one-charger-fits-all for mobile phones.
Developed by ITU–T Study Group 5 on environment
and climate change, Recommendation L.1000
(ex. L.adapter) on “Universal power adapter and
charger solution for mobile terminals and other ICT
devices” provides high-level requirements for a universal
power adapter and charger. This will reduce
the number of power adapters and chargers to be
produced and recycled by widening their application
to more devices and increasing their lifetime.
Wireless recharging is an area of research aimed
at replacing chargers and cables. The idea is to power
mobile devices on the fly, over distances up to
several metres, using non-radiative electromagnetic
coupling. The technology is already able to wirelessly
power devices such as DECT handsets in the range of
a few milliwatts up to kilowatts.
With all these promising new technologies, the
future of energy and communication for all looks
TechWatch Alerts are prepared by ITU’s Telecommunication Standardization Bureau (TSB) to provide a brief but
concise overview of emerging technologies and trends in the ICT field. The TechWatch Alert on “Batteries for portable ICT devices” was published in February 2010. The TSB is interested in your thoughts and feedback on its reports, and open to your proposals on
topics for future Technology Watch publications. Please send your comments to firstname.lastname@example.org.