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Even though they power many of our modern conveniences, batteries have a long history. Hank explains how and why these marvels work and what they've been used for over the past 2,000 years!

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Sources:
http://engineering.mit.edu/live/news/2037-how-does-a-battery-work
http://chemwiki.ucdavis.edu/Analytical_Chemistry/Electrochemistry/Voltaic_Cells/Case_Study%3A_Battery_Types
https://batt.lbl.gov/what-is-a-battery/
http://electronics.howstuffworks.com/everyday-tech/battery.htm
http://www.youtube.com/watch?v=GhbuhT1GDpI -- scishow lemon battery
http://news.bbc.co.uk/2/hi/science/nature/2804257.stm#story -- Bagdad batteries
http://www.allaboutbatteries.com/history-of-batteries.html
http://www.energizer.com/learning-center/Pages/battery-history.aspx
http://www.howstuffworks.com/electric-car.htm
http://electronics.howstuffworks.com/everyday-tech/lithium-ion-battery.htm
http://www.scientificamerican.com/article.cfm?id=how-do-rechargeable-that - rechargable
http://www.technologyreview.com/news/416973/cheaper-stronger-lithium-ion-batteries-for-electric-vehicles/
http://www.geek.com/news/how-a-lead-acid-battery-works-1501045/
http://auto.howstuffworks.com/fuel-efficiency/vehicles/electric-car-battery.htm
http://electronics.howstuffworks.com/everyday-tech/battery.htm
http://www.prlog.org/10815582-why-are-some-batteries-rechargeable-but-others-arent.html
In America, we have like three billion of these every year. Not double As, but batteries in general, and without some kind of battery to keep your phones ringing or your laptops searching, your flashlights running, your cars starting - what would you do?

We're totally dependent on battery technology and even though it's changed drastically in just the past few decades, the basic idea goes back thousands of years. So, how did we get here, and where does battery power go from here?

(Intro)

In the simplest terms a battery is a device that stores potential chemical energy in and converts it into electricity through reactions known as oxidation-reduction reactions. Any battery is basically an electrochemical cell, and in order for it to work it has to have three things: a positive electrode, or cathode, that wants more electrons, a negative electrode, or anode, that gives up electrons, and an electrolyte that allows ions to move back and forth between the first two, thereby creating a flow of electricity.

You've probably heard from us, or someone else, how to make a battery out of a lemon, where you can see these principles at work. Just take some copper wire which acts as the cathode, a zinc coated nail for the anode, and a lemon, which provides the electrolyte medium that connects the two. The difference in electronegativity between the anode and the cathode causes the reactions that produce a small charge of electricity.

It took a while for humans to get wised to the idea that these stored electrical charges could be useful. In the late 1930s German archaeologist Wilhelm Konig was poking around in Baghdad when he dug up an unusual artifact that made the world rethink the origin of batteries. It was a thirteen centimeter clay jar that held an iron rod encased in a copper cylinder, and contained traces of an acidic liquid, probably wine or vinegar. It was a really, really, really old battery, like two thousand years old. This blew some minds and the artifact remains kind of an oddity.

Experts debate what these batteries might have been useful for, but some believe they were tools in electroplating, the process of using electricity to apply a thin layer of gold or other metal onto a different metal to make jewelry and other ornaments. Scientists have actually replicated these battery jars and found they can produce one to two volts of electricity.

Preserve batteries have improved a lot since then, but the basic concept has essentially remained the same as those Baghdad jars. Italian physicist Count Alessandro Volta was long credited with creating the very first modern-ish battery back in the late 1700s. He stacked layers of brine-soaked paper between silver and zinc plates to form what became known as a 'voltaic pile' that emitted a steady current of electricity. Today we measure electromotive force in Volts in Volta's honor.

But while I agree that this pile was pretty sweet, it did have some major drawbacks, like how the salt water quickly corroded the metal plates. It wasn't until around 1836 that English chemist John Daniell made some major improvements. He invented the 'Daniell cell' by placing a copper plate at the bottom of a glass jar half full with copper sulfate solution, then topped it off with a zinc plate suspended in a zinc sulfate solution. The copper and zinc work on the same principles as that lemon battery we talked about, but in Daniell's cell, because the copper solution is denser, it kept to the bottom of the jar, while the zinc solution remained floating at the top, thus creating the first positive, on the copper end, and negative, on the zinc end, terminals of a battery.

As long as the Daniell cell remains still, like motionless, it worked like a charm, powering things like doorbells and telephones for years. It took another several decades for new improvements to pop up. In the mid 1960s Frenchman Georges Leclanché developed a contained carbon-zinc wet cell. It was smaller, more rugged, longer-lasting than a Daniell cell that would still work by immersing its electrodes in an acidic solution, in this case ammonium chloride. Later improvements used a barely moist paste of ammonium chloride as the electrolyte instead of a liquid, which meant that the battery could be jostled around without spilling all over the place. This was the dry cell battery concept which we still see today in alkaline, zinc, carbon, and mercury batteries.

By the end of the nineteenth century the National Carbon Company began selling the first commercial batteries in the US. That company eventually morphed into Eveready, which then became Energizer, which... this guy, here. And while today's batteries come in a wide range of shapes and sizes and materials, they all function basically the same way. Whether they're made of alkaline, zinc, lead acid or lithium, the electrochemical reaction and all three key components of anode, cathode, and electrolyte all remain.

Today the biggest difference in battery types is between primary, or disposable, and secondary, or rechargeable batteries. Disposable batteries are one-shot wonders. They produce electricity so long as the anode's chemicals keep releasing electrons and the cathode keeps accepting those electrons through the electrolyte. But once the chemical reactants are drained, the reactions stop and the battery dies. The lights go out. These include your everyday alkaline batteries which use an acquiesce alkaline for the electrolyte, and typically connect a zinc anode to a cathode made of manganese dioxide.

Rechargeable batteries, like nickel-cadmium or the lithium-ion ones tucked into your laptop, operate a lot more like two way streets. They lose all their chemical juice while producing electricity, but they can be recharged when plugged into an electrical source because the particular chemical reactions they use can be reversed.

Lithium is a super-super-reactive element, and its ions can be used to store a ton of energy. Lithium-ion batteries use lithium cobalt oxide as the positive electrode, carbon as the negative, and an organic solvent, often ether, for the electrolyte. These batteries are generally far lighter than other types of similarly sized rechargeable batteries, which make them particularly good for use in mobile devices. They also use oxidation-reduction reactions, of course, but because of the particular materials they use their chemical reactions can be reversed with the input of energy, and subsequently charged back up.

So when your laptop's on battery mode, discharging its juice, those lithium ions are moving from the negative carbon electrode over to the positive lithium cobalt oxide electrode. But when the battery gets plugged into the wall it recharges itself when those ions move back from the positive electrode to the negative side. It's like you could put the electrons back into the zinc-covered nail in your lemon battery and take them out of the copper wire over and over again. Thanks to lithium, you can!

The fact that you find rechargeable batteries all over the place now but you didn't like twenty or thirty years ago might make you think they're a fairly new invention, but they've actually been around for over 150 years - or at least one of them has. In 1859 Gaston Plante invented the lead-acid battery, the very first ever rechargeable battery. This heavy but effective wet cell combined a lead anode and a lead dioxide cathode bathed in a tub sulfuric acid, and it works so well that it is still starting cars today. Lead acid batteries do a great job of delivering a big burst of energy to start your car's engine, and then ration out extra energy for running your radio and lights and A/C and iPod while the gas-powered engine takes over the work of moving the car.

But electric and hybrid cars ask a whole lot more of their batteries, and old-school lead acid rechargeables just aren't enough to push around the Chevy Volt. So while an electric car might get an average of 130 kilometers off the juice of a lead-acid battery, a battery that uses your old friend lithium gets closer to 350 kilometers of a single charge. Not only that, but lead acid batteries can only be recharged so many times before they die for good, which you probably already know if you've had to jump start rig multiple times.

Lithium-ion batteries recharge nearly perfectly and can be drained and juiced back up hundreds of times without losing efficiency. Many believe the future of electric cars depends on building better and more efficient and more affordable lithium-ion batteries. Still, electric car technology has a ways to go. As it stands, not everyone has the time or the patience to return home and recharge a 450 kg -yes, they are that heavy- battery for eight hours a day, and the compounds that they run on do eventually get depleted after about five years, or 160 000 kilometers, at which point you gotta shell out ten thousand bucks for a new one, or just get a new car. So yeah, some kinks to work out, but hey, we're getting there.

The chemistry of batteries makes possible all of the electronic wizardry around you, and it's pretty darn cool to consider the basic function of those two thousand year old Baghdad jars hasn't changed that much, from electroplating ancient jewelry to you watching me right now to the future of electric vehicles.

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