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The clean energy revolution depends on batteries, but almost all the batteries we use today are made from lithium, a metal with a limited supply and a devastating environmental impact. Could we replace it with something more readily available?
快猫短视频 published a feature story about batteries made using common salt back in聽January 2021. These sodium-ion versions promised a cheaper alternative to those made of less abundant materials like lithium. But their inferior performance meant it was still up for debate whether these really were the batteries of the future.
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Nearly four years later, it is clear salt batteries have a role to play in the transition away from fossil fuels, with sodium-ion 鈥済igafactories鈥� springing up in places from India to North Carolina. This is good news for the planet for a few reasons.
Cheaper energy storage using sodium can help us cope with large amounts of renewable energy connecting to the grid. Abundant sodium may also limit the need to expand , such as cobalt, which have had harmful environmental and social effects.
Many sodium-ion batteries still contain problematic metals, including nickel, but new designs could eliminate these as well. One company is even planning a battery made from sodium and another abundant material: wood.
The trouble with lithium
The vast majority of batteries available today 鈥� from the small ones in cellphones to the big ones in electric vehicles 鈥� are made using lithium. These have been hugely successful because they are relatively light but can hold lots of energy. But the lithium-ion battery boom has created some big problems.
Demand for the silvery-white metal has prompted an expansion of lithium extraction, which can threaten ecosystems, freshwater resources and local communities. Current reserves of lithium are also concentrated in just a few parts of the world, posing risks to supply chains and exacerbating geopolitical tensions. The price of the metal has also fluctuated wildly over the past few years, creating headaches for the electric vehicle industry.
Researchers have long explored using sodium 鈥� a so-called alkali metal that sits just below lithium on the periodic table and shares many of the same properties 鈥� as an alternative. It is among the most abundant elements in Earth鈥檚 crust and a main component of table salt. Using it to make batteries would solve many of the problems created by sparse supplies of lithium.
But sodium isn鈥檛 a shoo-in. 鈥淭his material is not fantastically wonderful,鈥� says at the University of St Andrews, UK. 鈥淚t鈥檚 a good middle-of-the-road material.鈥�
Although they have improved, sodium-ion batteries still don鈥檛 perform as well as those based on lithium. In particular, they don鈥檛 store as much energy per unit of weight. This lower energy density is a particular issue for use of sodium-ion batteries in applications such as electric vehicles, limiting their practical range.
鈥淪odium-ion [battery technology] is like Usain Bolt,鈥� says at Natron Energy, a sodium-ion battery company in the US. It packs a lot of energy, but only for a short duration. The economic case for sodium-ion batteries has also weakened as the price of lithium has fallen steeply after hitting record highs in 2022.
Ready to power up
Nonetheless, the drawbacks of lithium, incremental improvement in sodium-ion batteries and the promise of even cheaper batteries to power the energy transition have spurred a surge of interest in sodium-ion versions, with a growing number of large-scale factories producing them coming online around the world. 鈥淚 think there鈥檚 the recognition that diversity is good,鈥� says Armstrong.
Around 90 per cent of these factories are in China, according to the International Energy Agency (IEA). Chinese clean energy giants CATL and BYD are building 鈥済igafactories鈥� large enough to produce more than a gigawatt of batteries per year.
But salt is also catching on elsewhere. In India, is outfitting a gigafactory to produce sodium-ion technology developed by Faradion, a British start-up. Meanwhile, in North Carolina, increasing its current manufacturing capacity by 40 times. In Sweden, a company called Altris is preparing to start commercial production of a sodium-ion cathode material for battery cells.
For the most part, these batteries are expected to be used for stationary energy storage, which plays a critical role to balance the electricity grid as growing amounts of intermittent renewables come online. In these cases, the weight of the batteries doesn鈥檛 matter because they don鈥檛 have to move. The IEA forecasts sodium-ion batteries will make up 10 per cent of all energy storage installed in 2030. Energy storage itself is booming, with countries at the COP29 climate summit pushing to increase such capacity sixfold by the same date.
鈥淚鈥檓 confident [sodium-ion batteries] will find their market when lithium becomes scarce and is used mostly for electric vehicles,鈥� , the director of energy storage research at the US Department of Energy, said during a recent about the potential for sodium-ion batteries.
Some of this technology might also be used to move people around in what Armstrong calls 鈥渃heap and cheerful鈥� vehicles. with sodium-ion batteries. With a range of under 300 kilometres, these won鈥檛 go as far on a single charge as those powered by lithium, but they are much cheaper and might be well-suited to urban settings. to supply sodium-ion batteries for e-bikes and small two or three-wheeled vehicles.
Sodium-ion batteries may have other advantages in addition to price and abundance. For instance, some designs can be transported without any charge in them, which limits the risk of fires, says Armstrong. They may also be able to function at colder temperatures than lithium-ion batteries, whose limits in this regard have posed a problem for charging EVs. that it has designed a sodium-ion battery that works normally at 鈭�40掳C (鈭�40掳F).
Good on paper
Sodium is abundant and can be collected from many sources. For instance, Armstrong says there is some interest among Gulf states in using sodium extracted from seawater by desalination plants to make batteries. But sodium is often mined, which inevitably has environmental consequences.
Most of the sodium battery designs now available also still use other metals that must be mined and smelted, like nickel and copper, meaning they retain some of the problems of lithium-based systems. 鈥淚f you鈥檙e still using nickel, it鈥檚 not night and day,鈥� says Armstrong.
However, even these may not be needed. Natron and Altris, for instance, both make some of their battery electrodes out of pigments called Prussian blue and Prussian white, respectively. The only other metals they contain, along with sodium, are iron and manganese. that uses hard carbon anodes made of lignin left over from paper pulp production.
Some years from now, perhaps we鈥檒l be commuting to work on an e-bike powered by a battery made of salt and wood.
