How and Why
Troves of lithium, valuable for batteries, boost mood in Bolivia and Afghanistan
In June, the Department of Defense announced that the mineral wealth of Afghanistan -- including iron, copper, gold and lithium -- might be worth more than $900 billion. Despite the historic importance of the first three, lithium seemed to be the material that most excited Pentagon officials, who gushed in internal memos about Afghanistan's becoming "the Saudi Arabia of lithium."
Afghanistan isn't the only country trying to hitch its wagon to lithium's star. Bolivia, too, has vast deposits and has also started to refer to itself as "the Saudi Arabia of lithium." An article in the New Yorker in March detailed the trouble Bolivia is having attracting investors to its lithium, mainly because of inadequate infrastructure and President Evo Morales's predilection for nationalization.
So what's so special about lithium? Sure, the batteries that power most of our portable electronic devices and hybrid-electric vehicles rely on it. But you don't hear anyone crowing about becoming the Saudi Arabia of manganese, cadmium or lead, all of them ingredients in conventional batteries.
First, a little Batteries 101. Batteries work on a simple principle. They stuff a whole bunch of electrons into a place they don't want to be. When you need power, your device (a computer, a cellphone or a plug-in car) provides a bridge for them to flow to a lower-density location. In the process, your gadget uses the energy that the electrons release.
The electron-dense region in a fully charged battery is called an anode. The electron-poor region is known as the cathode. So, when your battery is in use, electrons go from the anode, through your device, to the cathode. During recharge, the process is reversed, and the electrons are pumped back to their high-energy state.
"Think of the electrodes as two buckets that contain water," says Yang Shao-Horn, a professor of materials science at MIT. "One bucket is higher than the other. When the water moves from the high bucket to the low bucket, energy is released. During recharge, energy moves the water back to the higher bucket."
The useful life, power and rechargeability of a battery are determined by the composition of the anode, the cathode and the bath they're soaking in. Lithium batteries, which usually include cobalt and carbon in their chemical recipe, offer a number of advantages over those that contain traditional ingredients such as manganese, copper and zinc. For one thing, you can recharge lithium batteries safely and efficiently, whereas recharging alkaline ones can produce dangerous hydrogen gas.
More important for cars and power-hungry electronic devices such as computers, lithium packs a bigger electrical wallop than its competitors. The amount of energy that a chemical can generate inside a battery by gaining or losing electrons is known as its standard potential. Lithium has a standard potential of 3.04 volts, compared with just 0.76 volts for zinc and a measly 0.4 volts for cadmium, one of the original metals used in rechargeable consumer batteries.
Even if alkaline batteries had the molecular capacity to produce lithium-class energy, the process would be impractical. Most of them contain a water-based solution. Energies above two volts -- most alkalines are 1.5 volts -- can split water molecules, which would cripple the battery. Lithium batteries use a non-water-based system. (This is one of the reasons your laptop battery is so darned expensive. Because lithium reacts violently with water, the batteries have to be produced in a tightly controlled, low-humidity environment.)
Lithium has still more potential. Using current-generation lithium batteries, electric-only cars can travel no more than 250 miles before running out of juice. Shao-Horn's laboratory is tinkering with ways to increase that range. For example, by mixing lithium with oxygen from the atmosphere rather than with a material stored in the battery itself, you can get more energy per pound. Unfortunately, the so-called lithium-air battery can't produce quick bursts of energy in its present form, resulting in a car with very little pickup.
Lithium's electrochemical potential explains why engineers are so enamored of the element. But politicians are eager to begin mining for a different reason: No one really knows how much lithium is stored in the Earth's crust. With electric cars proliferating, demand might outstrip supply, sending prices much higher. Even after a slight retreat last year, lithium prices have more than doubled since 2003. Lithium prices are hard to pin down, though, and some estimate the increase at tenfold during that time.
This is a massive swing in the fortunes of lithium. Before engineers figured out it could be used in batteries, its main use was in mood-stabilizing drugs. (The soft drink 7-Up also included mood-boosting lithium citrate for two decades after its 1929 launch.)
Despite today's global enthusiasm for lithium mining, not all deposits are created the same. In the Salar de Atacama in Chile, companies drill through dried-up lake beds, exposing lithium-laced saltwater beneath, then evaporate the water. This is the cheapest method of extraction, which is why Chile and Argentina supply half of the world's lithium.
There are also significant deposits in Nevada, but much of them are tied up in soft clay. Extracting the mineral requires adding a couple of chemicals and cooking the mixture at more than 1,000 degrees. The process is more expensive than evaporation, but it's still cheaper than drilling into granite, as producers must do in Australia.
It's not yet clear how miners might extract Afghanistan's lithium or how much it would cost. As long as the metal remains in demand, though, the most important withdrawal plan for Afghanistan may be figuring out how to get the country's lithium out of the ground.
Palmer, a freelance writer living in New York, is a regular contributor to Slate.com's Explainer column.