25 May, 2010, Lux Fatimathas
‘Organic batteries’ for a brighter future?
Have you ever been about to send a text or make a call and at that crucial moment your phone just dies? Of course with the multifaceted phones of today, maybe you were about to listen to a song, send an email or watch something on YouTube. Whichever the case, the frustration as your battery sign flashes and your screen goes blank is universal.
Mobile phones have transformed from lowly oratory traffickers to all knowing personal aides. They wake us up in the morning, show us what the weather is, remind us of appointments and even tell us how to get to them. All of these wondrous applications however are energy-hungry [frax09alpha]processes and unfortunately for us our mobile personal aides don’t appear to have the stamina for it. Electrical gadgetry has advanced at a rate of knots but battery life has been left lagging behind.
Electric cars and wireless communication are viewed as decidedly modern creations, the epitome of twenty first century living. However just over a century ago car sales in America were dominated by the electric car, which outsold its combustible engine counterpart. What foiled the rise of the electric car was its battery life. Although sufficient for short journeys within the city, as the road networks developed outwards it simply couldn’t go the distance. Then came the discovery of crude oil in Texas and the cheap, mass-production of the combustible engine by Henry Ford. The electric car was relegated to the pages of history and the combustible engine flourished. A similar story of batteries found wanting also scuppered the spread of wireless telephonic communication – which again made its debut in the late nineteenth century.
Back to the twenty first century and technology has begun catching up with innovation, as is apparent from the “plugged in generation” – whether it be a phone, mp3 player or hybrid of the two. This is all thanks to the gradual improvement of the humble battery, which has undergone several different incarnations over the decades. The concept of a battery is simply a device which converts chemical energy to electrical energy, through the use of two electrodes connected by an electrolyte. The two electrodes have different chemical potentials and therefore either give out or accept electrons. The passage of these electrons from one electrode to the other generates electricity.
The forerunner of the modern, electric battery was the Voltaic pile created by the Italian physicist Alessandro Volta. Voltas initial battery assembly consisted of repeated sandwiches of two different metal electrodes and a rather unique electrolyte – frog legs! This unusual choice stemmed from the observation made by Voltas contemporary, Luigi Galvani, that dissected frog legs would twitch when the nerves came in contact with a steel scalpel. Within a year of these experiments, the frog legs had been upgraded to brine-soaked paper.
Following this amphibian epiphany, batteries steadily evolved into the mass-marketed packages we now know. From lead-acid to zinc-manganese to nickel-cadmium – and not a frogs leg in sight. The staple AA battery was as portable as energy sources got in the 1980s and so music lovers worldwide dutifully loaded up their Walkmans with two AA batteries. Thirty years later and technology has shrunk. More efficient and importantly compact lithium ion/cobalt batteries are now the mainstay of mobile phones, laptops and mp3 players.
However the glass ceiling is still fast approaching, beyond which lie countless complex, power-hungry applications. In order to surpass this barrier new, sustainable, long-life batteries are needed. In 2007 the release of the iPhone was delayed due to a number of problems, including the need for longer battery life. Similar rumours were abound with the release of the iPad this year. These technologies have largely been a great success, though any user will know that charging up is a nightly ritual.
Researchers are plugging away at a new batch of batteries set to give the old timers of the lithium ion/cobalt era a run for their money. The concern over battery lifetimes, though of paramount importance when you’re phone blacks out on you, pales in significance to the pressing problem of sustainability and environmental pollution. Mineable cobalt, lithium and cadmium sources are finite and the reactions needed to make these inorganic electrodes produce significant carbon footprints. In the not too distant future, it seems these inorganic batteries will have to make graceful exits from the battery manufacturing show.
Enter the world of organics – a term that in our futures may no longer be restricted to the fruit and veg aisle of our local supermarkets. Research suggests that renewable, organic sources of lithium could be used to power batteries and better yet, could be extracted from plants in an energy-efficient manner (Chen et al 2009 JACS, Chen et al 2010 ChemSusChem). Organic lithium molecules (LixC6O6) can be produced from a natural compound called phytic acid, which is present in many plants and particularly enriched in wheat bran and flaxseed.
It seems it isn’t just the cereal aisle that has inspired the field of battery technology, but the drinks aisle too. Vodka, white wine and gin – all sources of ethanol that have been tried and tested as fuel sources in enzymatic batteries (Minteer lab, Saint Louis, US). The next inspirational aisle is that of the seafood section. There you will find yet another muse for the battery scientist – the humble eel. The electric eel packs a powerful punch of up to 500 watts and devotes approximately 80% of its body to this function alone. Researchers are currently investigating a man-made mimic of the structures that comprise the eels electricity generating organs (Kim and Cho 2009 J. Micromech. Microeng).
With all these new contenders in the mix, the future of battery technology is hopeful. But until those super-powered, long-lasting batteries get here, just remember to keep on charging.
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