Lithium and the Battery Age

Lithium is the lightest of all metals, so soft that it can be cut with a knife and so reactive that it must be stored away from air and water. For most of its history it was a chemical curiosity of interest chiefly to scientists. Today it has become one of the most sought-after materials in the world, because it lies at the heart of the rechargeable batteries that power mobile phones, laptops and, above all, electric vehicles. As countries attempt to move away from fossil fuels, demand for lithium has surged, and the metal has acquired a strategic importance that few would have predicted a generation ago.

The reason lithium is so valuable in batteries has to do with its physical properties. Being extremely light, it allows batteries to store a large amount of energy without adding much weight, a quality that matters enormously in a car or a phone. Lithium-ion batteries can also be charged and discharged many hundreds of times before their performance noticeably declines, and they lose their charge relatively slowly when not in use. These characteristics made them the natural choice as portable electronics spread through the 1990s, and the same advantages now make them central to the shift towards cleaner transport. A single electric car may contain thousands of individual cells, and the battery pack is typically one of the heaviest and most costly parts of the whole vehicle, which is why even small improvements in the way lithium is packed into a cell can translate into meaningful gains in range or price.

The metal is obtained from two main sources. The first is hard rock, chiefly a mineral called spodumene, which is mined from the ground and then processed at high temperatures to extract the lithium it contains. The second is underground brine, salty water pumped from beneath dry salt flats, most famously in a region of South America sometimes called the lithium triangle. There the brine is spread across enormous ponds and left for many months, so that the sun evaporates the water and gradually concentrates the lithium that remains. Each method has its own costs and drawbacks, and the choice between them depends on geology, climate and the price that producers can command.

Extracting lithium, however, carries an environmental price. The evaporation process consumes vast quantities of water in regions that are often already extremely dry, and this can bring mining companies into conflict with local farmers and communities who depend on the same scarce supply. Hard-rock mining, for its part, disturbs the landscape and requires a good deal of energy for processing. Critics point out that a technology promoted as clean therefore has consequences that are anything but invisible, and they argue that these impacts must be weighed carefully against the benefits of reducing emissions from vehicles.

Supply is a further concern. Although lithium itself is reasonably abundant in the Earth's crust, deposits that can be exploited profitably are concentrated in a handful of countries, and the facilities that refine the raw material into battery-grade chemicals are more concentrated still. This uneven distribution has raised worries about the security of supply, since a disruption in one region could ripple through the global market. Governments and manufacturers have responded by seeking new sources, by signing long-term contracts and by investing in their own processing capacity so as not to depend too heavily on any single supplier.

Recycling is widely seen as part of the answer. Because the lithium in a spent battery does not disappear, it can in principle be recovered and used again, reducing the need for fresh mining. In practice, recycling has been held back by the difficulty of collecting used batteries and by the complex processes required to separate their valuable components. As the first generation of electric-vehicle batteries reaches the end of its working life, however, a larger and steadier stream of material is expected to become available, and improved techniques may make recovery more economical than it has been so far.

Researchers are also working on batteries that would reduce reliance on lithium altogether. Some designs replace it with sodium, a far more common element, while others aim to squeeze more energy from each unit of lithium so that less is needed overall. It is too early to say which of these approaches, if any, will displace the lithium-ion battery from its dominant position. What seems clear is that batteries of some kind will remain fundamental to a low-carbon future, and that securing the materials to make them, whether through mining, recycling or new chemistry, will be one of the defining industrial challenges of the coming decades.