Monday Musings – Batteries

Ok, so at first glance, batteries might not be the most exotic technology to explore, but after reading an exciting article about graphene and how it can affect battery performance (and almost everything else electrical), I decided it was at least interesting enough to write about. Jump past the break to talk more about this surprisingly fascinating technology, and how it affects your every-day life!

First, I found it fascinating to learn exactly how batteries actually work. The specifics are more complicated than I would have thought, but the basics are pretty … basic: At one end, a material called a “cathode” reacts with another material, called the “electrolyte” to lose electrons. At the other end, another material called an “anode” reacts with an “electrolyte” (not necessarily the same material as the one at the cathode end) to gain electrons. The trick is that the electrolyte doesn’t allow the electrons to pass through it. So, the anode and cathode are connected by a conductive wire, which passes through what is called a “load,” which is simply something for those electrons to do – like activate a light bulb. The other trick is that these chemical reactions which produce and consume electrons only happen if the circuit is closed (if the wire actually makes a connection between the cathode and anode). This is important, because eventually the cathode and anode will reach a point of stability in which the reactions won’t happen anymore. When that happens, electrons will no longer flow through the wire, and work will no longer get done. That’s what we call a “dead” battery. 😛

So, the true issue seems to be those all-important electrochemical reactions at the cathode and anode. The more efficient that reaction (the more electrons it produces while using the least amount material), the better the battery. The first demonstrable battery (barring a recently discovered ancient possibility) was created by Alessandro Volta in 1800. Called a “Voltaic Pile,” it was built with alternating plates of zinc and copper (the anodes and cathodes) separated by brine-soaked cardboard (the electrolyte). At that time, there were no electrical grids, and the voltaic pile couldn’t provide power for very long. However, in 1836, John Frederick Daniell designed the Daniell Cell which used two electolytes (copper sulfate and zinc sulfate) and lasted much longer. It only produced about 1.1 volts of power, but that was enough to run things like telegraphs, telephones, and doorbells, and remained popular for over 100 years). It wasn’t until 1859 that scientists figured out how to reverse the process and Gastone Plante invented the first lead-acid rechargeable battery. This is the same type of battery still in use in automobiles today.

But battery science hasn’t stopped there, and good thing too, because our need for them has only increased over the years. Nowadays, with the ubiquity of mobile devices, and the increasing possibilities for electric vehicles, batteries have become a true bottleneck to progress in these areas. Currently, Lithium-Ion batteries use a graphite anode, a metal-oxide cathode, and an electrolyte of lithium salt. Lithium ions are forced from the cathode side to the anode side, creating the electrical difference necessary for the battery to work. Apparently, this causes a very high energy density – which means that it can hold a lot of potential chemical energy – but a very low power density – meaning that it can’t provide a lot of “work” while discharging, and it takes longer to charge. This doesn’t cause much of a problem for smaller power requirements – laptops, cell phones, etc., but it’s definitely a huge concern for more intense loads – like electric cars.

The idea of a fully-electric car is something that I’ve been extremely excited about for a long time, so recent advances in battery technology have me all a-twitter. In 2009, folks at MIT discovered that the Lithium Ions were travelling across the battery much more slowly than they should. Their solution was to re-engineer the substance so that lithium ions could “easily” find the tunnels through the material. The article didn’t get to scientific, so I’m not sure how that works, but it has been 4 years since the article was written, and I – sadly – have not seen this make its way into the commercial space.

But, all is not lost. According to a recent article, graphene – a fantastic variation of the more commonly known graphite which apparently has all sorts of applications, including those in the realm of computer science – has the possibility of improving lithium ion battery performance by as much as 10 times. This is achieved by the very simple – but extremely difficult – method of punching holes in the layers of graphene which allow the ions to navigate through the material faster than ever. But it doesn’t stop there! Apparently, graphene can be used to make supercapacitors, which are more powerful than traditional batteries, and recharge almost instantly. They don’t have a lot of capacity, but opportunities for very exciting things abound!

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