Why are mobile phone batteries still so crap?

1st Oct 2013 | 10:00

Why are mobile phone batteries still so crap?

Battery life hasn't kept pace with advances in mobile computing - but that could change soon

Mobile computing promises the world: web access, photos, music and maps, everywhere you go. And it can really deliver - for a while. But poor battery life means you'll probably soon run into problems, with some devices leaving you staring at a useless blank screen well before the end of the day.

There are some steps you can take to keep your system running longer, of course. The display is a major mobile phone energy hog, so reducing its brightness and timeout (the time a phone waits for input before turning the screen off) can make a significant difference.

Turning off GPS, Bluetooth and Wi-Fi when you don't need them also helps. This doesn't always have to be as absolute as it sounds. On the iPhone, for instance, you can disable Location Services on an app-by-app basis (Settings > Privacy > Location Services). On the software side, uninstalling apps you don't use will stop them draining your battery.

Why are batteries still so bad?

There are also tools you can use to extend your battery life. JuiceDefender, for instance, is an excellent Android app which automatically optimises power use.

All of these steps can bring minor improvements but none can make the fundamental difference we need. And you might be left wondering why battery life is still so poor, and what's being done to improve the situation.

Feature overload

Perhaps the main problem with battery life over the years is it really doesn't seem to have changed that much.

Take the iPhone, for example. The original device had a claimed talk time of 8 hours; the iPhone 5 is, well, the same. Internet use has nudged up from 6 hours to 8, and claimed standby time has actually dropped (225 hours vs 250).

There are very good reasons for this, though, and the main one is that you're now getting much more for your money.

A modern iPhone has gained 3G support, a vastly better screen (480 x 320 vs 1136 x 640), GPS, and the excellent iSight camera (8 megapixel vs 2). On top of that, there's the ability to run multiple apps in the background, each of which could drain your power further at any time. The fact that the latest iPhones can power all these extra functions while also fractionally extending overall battery life is a success story, not a failure.

Why is battery life still so bad?

This doesn't mean that the existing situation is good enough, of course. When, even now, many devices struggle to run for a full day without a recharge, then it's clear we need something better. Much better. And there are some promising technologies being developed right now which could point us in the right direction.

Extending Lithium-Ion

Today's lithium-ion batteries are straightforward and safe (well, mostly), but also have their limitations. In particular, the graphite anode they generally use has to be fairly large to store a reasonable amount of power, and so there's a great deal of research going on to find a less bulky replacement material.

Silicon anodes, for instance, could help increase battery capacity by up to 10 times. But the big problem is that a simple flat layer of silicon absorbs so many ions that it actually grows significantly during charging, then shrinks during discharge, creating stresses which mean it destroys itself very quickly.

Recent research at the University of Maryland, however, found that growing tiny silicon beads on a carbon nanotube allowed them to expand during charging "like flexible balloons", without cracking. UMD Professor YuHuang Wang told us: "I believe that our finding is very significant. The Si bead on CNT structure is a breakthrough."

Why are batteries still so bad?

There is still much to do - the cathode and electrolyte also need to be able to handle this extra charge - but if Wang is right then this could help to deliver vastly improved power density, as well as batteries which can survive perhaps five times as many charge/ discharge cycles as they do today.

Others are working on lithium-sulphur, lithium-seawater, even lithium-air projects, each of which has their own possible advantages. PolyPlus seawater technology could deliver four times the battery life of li-ion, for instance, while "air-cathode" research (including IBM's Battery 500) suggests the batteries wouldn't only outperform li-ion, they'd be so lightweight that they could allow electric cars to finally have the range of their petrol-based cousins.

Next generation

While some think simply tweaking lithium-ion is the way to go, others are working on rather more revolutionary ideas.

Perhaps one of the most promising areas of battery research is based around graphene. A single layer of carbon, the material can vastly outperform existing technologies, recharges in a few minutes, and is even flexible, perfect for wearable devices.

Science fiction? Not at all. The UK government has allocated £21.5 million to develop commercial applications for the material, and companies like Vorbeck Materials are working on producing graphene batteries right now.

Elsewhere, Harvard Professor Jennifer Lewis has demonstrated the use of 3D printing to build an integrated stack of electrodes, which could allow batteries to be reduced to the size of a grain of sand.

Why are batteries still so bad?

At the moment, the main benefit is the reduction in weight, Lewis told us: "We are working on the next generation design with improved electrode compositions to further enhance their performance. We certainly hope that they will outperform regular Li ion batteries, but this has yet to be demonstrated."

Another new idea goes a step further, rethinking battery technology at a much lower level. New microbatteries developed at the University of Illinois integrate their anodes and cathodes at the microstructure level, allowing recharge times to be 1,000 times faster, and batteries to be one thirtieth of their current size.

"It's a new enabling technology," said James Pikul, first author of the paper: "It's not a progressive improvement over previous technologies; it breaks the normal paradigms of energy sources. It's allowing us to do different, new things."

Power up

The future of batteries has plenty of promise, then - but mobile users need more power right now. The quickest workaround seems to be finding new, hassle-free ways of recharging. And they don't get much more convenient than Wysips Crystal, the first solar recharging technology you might actually want to use.

The system uses an ultra-thin film which can be placed behind your device screen. It's up to 90 per cent transparent, so you won't even know it's there, yet is still enough to generate a useful recharge level from any source of light.

Why are batteries still so bad?

What can you expect? The company told us: "Right now the system generates 2.5 mW/cm2 in direct sunlight, which should mean an extra 2 to 4 minutes talk time for every 10 minutes of exposure."

Only really useful in an emergency, then, but there's more. The company aims to double this performance by the end of 2014; it's also due very soon, and at a price that everyone can afford. The company explained: "Wysips Crystal adds just $2.30 to a mobile phone's manufacturing costs, and the first mobiles equipped with the technology will be on the market in early 2014."

Here in the UK, of course, direct sunlight can sometimes be hard to find, but fortunately there's another long-awaited technology which is coming very soon: wireless recharging. It's already available at a few places in the US (Madison Square Garden has 600 wireless charging spots), for instance. And the idea could be about to go very mainstream indeed, with Starbucks apparently due to introduce the technology soon, and McDonald's Europe already beginning trials.

The battery world may move very slowly, then, but finally it's beginning to change, and we should see the emergence of real, meaningful improvements in current technology as soon as next year.

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