This weekend rare and fabulous news came from Afghanistan that trillion-dollar mineral deposits have been discovered. Chief among the riches is lithium, an element central to the most popular type of rechargable batteries used today. But what exactly is lithium and how do the batteries work?
Lithium the element
Lithium, properly discovered in 1817, is a an alkali metal in the same family as sodium and it's actually a soft metal under normal conditions—you can cut it with a knife. It's also the least dense solid element and the lightest metal, meaning it can actually float on water, but it's incredibly reactive and flammable in air and water so it has to be stored beneath a sticky oil in laboratory environments.
Lithium has multiple uses in the modern world, including as a mood-stabilizing drug, but its first serious industrial use was during the second World War as part of high-temperature lubricants that were perfect for use in aircraft engines. The U.S. was the world leader in lithium production from this era until the 1980s when vast South American deposits began to dominate.
The metal's high reactivity means it's not found in nature as a pure metal, instead being found as a chemical compound—although it's pretty rare, and is just the 25th most abundant chemical element in the Earth's crust. It's often extracted electrolytically from a lithium chloride/potassium chloride mix.
Batteries based on lithium technology are the most popular rechargeable batteries at the moment. This is because they're light, reliable, they don't lose charge quickly if not used, and they have no memory effect (the degradation in performance seen after many charge-discharge cycles that plagued NiCAD batteries before lithium took over).
Inside a battery there's typically a carbon anode, a metallic oxide cathode and the lithium present is dissolved in an organic solvent. When you apply a charging current through the battery, Li+ lithium ions physically move through the battery to the negative electrode from the positive one, becoming embedded in the porous material there. When you then put the battery into your electronic gear the ions slowly make their way out of the electrode and drift through the battery to the positive electrode, resulting in a flow of current through the battery and thus powering your gadget.
Simple, isn't it? The only trick is that the batteries need a few physical, chemical and electrical protections built in so that they keep working under normal circumstances and so that they don't explode if they malfunction (by getting too hot, for example). Failures in these systems explain the occasional headline you've seen about people being hurt by failing cell phones, but in reality these accidents are extremely rare.
Technology that may displace lithium batteries
The Afghanistan government will suffer from little previous expertise in mining operations on a commercial mega-scale, and limitations from zero existing infrastructure. But if it's to capitalize on the vast cash potential in its lithium deposits it needs to move relatively quickly. Lithium battery tech is so promising it's not going to go anywhere soon, and our gadgets will certainly rely on Li-ion technology for many years yet. But there are several technologies en route that may eventually displace it from being the power source of choice.
Alternative battery tech—Much research is going on to try to improve rechargeable battery technology. One seriously viable alternative, already on the market in small numbers is nickel-zinc. The chemistry of their design means they offer slightly higher voltages than can be gained from Li-ion, they're non-toxic and claim to have the most recyclable components of any battery.
Fuel cells—We hear lots about fuel cells in terms of electric vehicle design, but portable fuel cells for gadgets already exist. The plan is to minimize the size so that eventually your cell phone may need just a tiny puff of butane every now and then to power it.