Salt of the earth: Sodium-ion batteries are the safe, cheap and abundant alternative to lithium
Next year electric bike giants Niu plan to launch a scooter powered by a sodium-ion battery rather than the lithium-ion cells which have become ubiquitous across the burgeoning electric bike market.
And despite suggestions that it’s a backward step in terms of performance, sodium-ion technology could become dominant in the future as a cheaper, safer and greener alternative to lithium.
UK-based Faradion are leading lights in the effort to take sodium-ion batteries to mass production, and this year were bought by Reliance New Energy Solar Ltd, themselves a subsidiary of Reliance Industries, India’s largest private sector company, for an astonishing £100 million.
![Faradion sodium-ion battery Faradion sodium-ion battery](https://mcn-images.bauersecure.com/wp-images/189424/820x0/faradion-sodium-battery.jpg)
As well as being deployed directly in electric vehicle batteries, the technology is intended to be used as storage for fast-chargers – essentially acting as the equivalent of storage tanks at petrol stations, but for electricity, recharging during quiet periods and helping to prevent the electricity grid from being overloaded when a glut of vehicles are charging simultaneously at peak times.
The idea behind sodium-ion batteries is to provide, in Faradion’s own words, ‘lithium-ion performance at lead-acid prices’ by using sodium – which is widely available across the globe and can be extracted from salt – instead of lithium, which is relatively scarce and expensive.
The batteries themselves work on the same principle as lithium-ion batteries – the two elements are adjacent on the periodic table and have similar properties – but making the chemistry work in a commercially viable battery is the subject of a vast amount of work.
![Battery cells in an urban scooter Battery cells in an urban scooter](https://mcn-images.bauersecure.com/wp-images/189424/820x0/electric-scooter-batteries.jpg)
The rewards could be huge. CATL (Contemporary Amperex Technology Co, Ltd) – a Chinese company that’s the world’s largest manufacturer of lithium-ion batteries for EVs, with a market share of 32.6% in 2021 – unveiled their own sodium-ion battery last year, reflecting a growing concern that a replacement for, or at least an alternative to, today’s lithium-ion battery technology is needed.
Lithium prices have rocketed recently: in late 2020 lithium hydroxide used in Li-ion battery cathodes cost as little as $9 per kilogram, but that’s risen to around $75 in August 2022. Prices for lithium carbonate, used in electrolytes for Li-ion batteries, have followed a similar trajectory, thanks largely to the rapid rise in electric vehicle sales.
Within a few years EVs are expected to outsell combustion-engined vehicles, and some forecasts predict that the global supplies of lithium will become unable to keep pace with demand by as early as 2030.
![CATL sodium power cell CATL sodium power cell](https://mcn-images.bauersecure.com/wp-images/189424/820x0/catl-sodium-ion-battery.jpg)
The wide availability of sodium also means that supplies aren’t restricted to a few key parts of the world, which means sodium-ion batteries can be made using locally sourced materials, without as much environmental damage as the mining required for elements in lithium-ion batteries.
On the downside, current sodium-ion batteries are not quite as energy-dense as lithium-ion, so they’re more suited to lower-performance and range vehicles – for instance scooters – than faster bikes. CATL’s first-generation sodium cells manage 160Wh/kg, but the company are targeting energy density of 200Wh/kg from its next-gen batteries, which is approaching Li-ion levels, which are good for around 250Wh/kg.
Sodium-ion batteries in detail
Urban solution: The energy-density isn’t as high as Li-ion batteries (at least, not yet), making them more suited to energy storage at charging stations or for lower performance, cheaper scooters and city bikes.
Coming (very) soon: With CATL sodium-ion battery production due to start in 2023 and NIU set to launch a scooter using the same technology that year, sodium-ion batteries are genuinely on the verge of commercial availability, not endlessly ‘just around the corner’.
Flexible performance: Although less energy dense than Li-ion, sodium-ion cells can recharge fast – CATL claims 0-80% charge in 15 minutes – and retain charge well in cold weather, keeping 90% of their performance at -20°C.
Greener option: Sodium-ion batteries are essentially similar to lithium-ion cells but use much more widely available raw materials to cut down on costs and ecological damage from mining for lithium.
Safer storage: Unlike lithium cells, which can’t be discharged below about 30% of their capacity, sodium-ion batteries can be emptied to zero volts, making them safer to store and transport.