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The battery: the Achilles heel of mobile electronic devices

How can we increase the autonomy of our mobile phones, pads and other gadgets? Scientific research is being mobilized to tackle this problem… an issue that potentially has vast commercial repercussions.

October 2014

IMALab The battery: the Achilles heel of mobile electronic devices

A major smartphone manufacturer recently released a video making fun of a rival manufacturer’s product by showing a series of people frantically searching for an electric socket in the most unlikely situations, desperately trying to recharge their cellphones.

The sequence, which quickly went viral, was a clear symptom of the growing battle between mobile device producers, focused on the problem of battery autonomy.

We need to remember that battery technology has changed remarkably little in the past 50 years, which is all the more bizarre when one thinks of the unimaginably revolutionary advances made by the devices they power.

The humble AA battery has been around since the 1940s and is based on 19th Century technology. But it still has a 15% share of the global battery market, along with other alkaline batteries. And the lead-acid battery, which is fundamental to most combustion engine-powered cars, was invented more than 150 years ago and yet it still holds a 20% share of the market. Even the more recent rechargeable lithium-ion battery, which powers most modern gadgets, was invented in the 1970s. But it still hangs on to a market share of roughly 40%.

One of the sectors where research has a crucial strategic role to play is that related to batteries for electric cars, where a breakthrough could have hugely positive environmental consequences. The saying goes that the whole development potential of this sector revolves around two numbers: 300 and 100.

The 300 refers to the number of miles that electric cars need to be able to travel on a single battery-charge for Americans to take them seriously. The 100 refers to the number of dollars per kilowatt-hour to which batteries need to drop before electric vehicles can compete with gas-powered cars on sticker price.

Tesla, the electric vehicle pioneer, thinks that the so-called 18650 lithium battery still has a future, even though it’s a relatively old technology. This is because, when smaller cylindrical cells are used, they can achieve a higher energy density, and by putting 7,000 of these cells together, Tesla's Model S Sedan is actually able to achieve an autonomy range of up to 300 miles.

Most other manufacturers use pouch cells, which involve lithium cells being placed side by side like slices of bread. The danger here is the risk of "thermal runaway", where one cell short-circuits and produces so much heat that it sparks a ripple effect which ends with the battery blowing up.
The next generation of lithium-ion batteries will help solve this problem by replacing flammable liquid electrolyte with safer, solid-state components. This type of battery will also be more powerful per unit.

Some companies, meanwhile, are trying to develop lithium-sulfur batteries, which promise to offer five times the energy of a standard lithium-ion: it remains to be seen how viable these attempts turn out to be. In many ways, the more realistic and exciting developments are currently taking place away from pure battery technology. One such case is wireless power, i.e. charging your gadgets without having to plug them in to the electricity mains.

One company pioneering this new technology is Ossia. Its founder and chief executive Hatem Zeine discovered that a small amount of power is transmitted alongside radio waves, and set about researching how best to focus the signal from many antennae working in unison as a means to charge devices remotely. In 2013, Mr Zeine launched Cota, a unit composed of two parts: a charger and a power receiver.

The receiver sends out a low power signal to the charger, which in turn sends back a signal from each of its thousands of radio antennae, targeted specifically at the receiver. The receiver will then track the device constantly and the phone or laptop will be automatically charged whenever it is within range of a charger. So we could envisage a time when we need far fewer power sockets because remote chargers will be installed throughout our homes, offices, public buildings, cars and trains.

The Swedish company MyFC, an offshoot of the Royal Institute of Technology in Stockholm, has developed a portable fuel cell consisting of an electro-chemical device that converts hydrogen into protons and electrons. The protons go through a membrane and react with oxygen, so the only bi-product is water. This means that it becomes possible to recharge a device using just some water and a small sodium silicide refill canister, anywhere at any time.

The product is called Powertrek, and in one year it has sold 10,000 units in 24 countries.
But, given that mobile phones and tablets are currently selling at a rate of about two billion a year, this solution would appear to have a long way to go before it becomes a swing tendency.

Other research areas being investigated might appear to have a taste for bizarre approaches. Researchers from the American Chemical Society of San Francisco, for instance, have presented a research study with the striking title “Epidermal Biofuel Cells: Energy Harvesting from Human Perspiration”.

Strenuous exercise generates lactate and the device designed for this project strips electrons from lactate, which creates a small electric current that could be used to develop a sort of sweat-powered “bio battery”. Unfortunately, so far their proof-of-concept setup topped out at only about 4 microwatts of electrical charge, not even enough to run a watch.

So, research into new ways of generating and storing energy continue and multiply, involving all kinds of materials…  from water to sweat, from rhubarb to paper, and from viruses to urine.

Meanwhile, for the moment we’ll just have to resign ourselves to the fact that our indispensable mobile devices have frequently to be immobilized and tethered for several hours to a hole in the wall.