Sodium-ion batteries have been hitting the headlines this year as attention switches to new battery technologies offering potential alternatives to lithium-ion batteries for the future. How this might impact on the demand for salt is a long-game but perhaps a more significant growth driver for salt than first thought?

Sodium-ion batteries are still in a very early stage of development but are being talked about as potentially being able to revolutionise the battery industry - the achievement of climate change goals will require cheaper batteries to make them more accessible, especially in the automotive sector. Sodium-ion batteries, despite initial reservations about bulk and lower energy efficiencies, are making the first inroads as significant research and development has been stimulated by high lithium prices and potential supply concerns. 

Until recently, sodium-ion batteries have mainly been used in micro electric vehicles, mainly two-wheelers such as scooters, e-bikes and rickshaws and also in energy storage systems. However, over the last 12 months there have been several leaps in commitment to the technology by major car companies. 

A relative newcomer on the battery scene, HiNa, a JAC-Volkswagen Anhui joint venture in China, produced the first sodium-ion battery powered small test car at the end of 2022. The company was founded in 2017 and launched its first sodium battery that year. By the end of 2022, it had started its own 60GwH scale sodium-ion battery production line.  

The first generation of HiNa batteries gave energy density figures of 125Wh/kg, which is around half that of lithium-ion batteries. The model has a range of 252 km according to Chinese standards and supports fast charging up to 4C. The battery pack uses sodium-ion cells with an energy density of 140 Wh/kg. HiNa is aiming to develop the battery further and the company sees potential in using it in large-size electric vehicles in the future. 

However, although HiNa may have been first out of the starting blocks, the race is on in the automotive sector. Chinese car manufacturer BYD, has announced that it is building a 10GwH sodium-ion battery factory in Xuzhou, China, with start-up scheduled in 2024. It has designed a battery system for a small EV using sodium-ion and lithium-ion batteries in series. Elsewhere in China, CATL is also reportedly going down the same route of using sodium-ion and lithium-ion in series, with mass production of the car slated for end 2023, although it has yet to announce any sodium-ion battery capability. 

Although the use of sodium-ion batteries is in its infancy in the automotive industry, while development takes place so that they can compete with the fast charging capability and EV range of lithium-ion batteries, there are other opportunities in alternative areas such as stationary storage and micro-mobility where they are gaining traction. US company, Natron Energy is already selling sodium-ion units into data storage centres, as sustainable backup power for telecoms and as a replacement for lead-acid batteries. In December last year, the company announced that United Airlines had made a strategic investment. The airline is not yet looking at electrifying planes but its ground operations. The sodium-ion batteries will be used to provide the high power over short distances that the ground service equipment needs. A major advantage for sodium-ion batteries in these circumstances is that they are non-flammable.  

Reliance Industries in India is also invested in sodium-ion technology with its acquisition of UK technology company, Faradion, for £100M in December 2021, with a commitment for another £25M to accelerate commercial roll out. Reliance will use Faradion’s technology at its proposed energy storage giga-factory as part of the Dhirubhai Ambani Green Energy Giga Complex project at Jamnagar in western India. Reliance sees the technology as securing India’s energy storage requirements for its large renewable energy and fast-growing EV charging market.  

Proponents of sodium-ion batteries claim that the total costs of ownership are comparable to lead-acid, that performance can be largely on a par with lithium-ion phosphate batteries, and that the technology has some key advantages compared with lithium-ion, including safe transportation and storage capability, and the opportunity for scalability. 

Perhaps the most important advantage of sodium-ion over lithium-ion is related to a lower cost of materials. While some proposed cathode chemistries for sodium-ion applications will use existing ternary materials, it is the substitution of lithium with sodium that provides the greatest potential cost saving. Sodium is processed from salt, and there is definitely no shortage in supply. Salt is produced in over 100 countries, and resources are unlimited.

Project Blue’s high-case sodium-ion scenario sees the new technology scale up commercial production over the last part of the decade before growing rapidly in the key markets for smaller EV applications and energy storage systems (ESS). Under this high-case scenario sodium-ion batteries would contribute to 1980 GWh of EV demand and 480 GWh of ESS demand in 2050. The salt required to process and produce that scale of sodium-ion production in 2050 would approach three million tonnes, which is roughly 1% of the current total production of processed salt in 2023. This scale of potential sodium-ion demand would elevate sodium, and the salt required to produce it, firmly into critical material status for delivering energy transition.