As Moss Landing smoulders, what are the prospects for safer salt batteries?

The latest fire at the massive Moss Landing battery in California has thrown the spotlight onto battery chemistries, including which lithium-ion varieties are more susceptible to fires, which are less, and when various much-safer-again non-lithium alternatives might be ready to compete.

Cheap lithium-ion batteries have crowded out almost all other storage technologies, but the downsides include a high fire risk – particularly in the sort of NMC (nickel, manganese and cobalt) variety believed to make up at least part of the Moss Landing big battery – as well as ethical and supply problems in critical metals including lithium, cobalt, nickel and graphite.

Sodium-ion batteries have long been seen as the next option on the technology drawing board, given the abundance of salt and ability to easily drop sodium tech into lithium battery manufacturing lines. 

But a new study out of Stanford University in the US has warned that sodium-ion batteries are approaching price parity with lithium slower than expected because of technical challenges around energy density and the current low, low prices of lithium. 

Catching up with lithium-ion will require “substantial” leaps in technology and favourable market conditions, says PhD candidate Adrian Yao, lead author of the Nature Energy paper and former founder and CTO of lithium battery startup EnPower.

“Lithium-ion batteries have been responsible for nearly all new deployments of storage in recent years, largely enabled by the tremendous cost declines over the past three decades of commercialisation characterised by an aggressive learning rate where prices have fallen by more than 97% since they were first commercialized in 1991,” the paper says.

“However, in response to severe post-COVID lithium price spikes, manufacturers recently announced over 240 GWh of Na-ion cell manufacturing pipeline through 2030, promising lower prices than Li-ion.”

The Stanford research says when and by how much sodium variants might be cheaper, is “still largely a matter of speculation”, and is much less optimistic than timeframes being speculated about last year. 

An AI analysis that used a method developed by the Massachusetts Institute of Technology (MIT) suggested sodium-ion batteries might be commercialised as soon as 2027, and might even match gas-fired power on cost as a firming energy source.

The United States energy department thought they might be already taking “significant market share” by 2030 in small vehicles and as home batteries. 

Chinese electric motor vehicle company BYD reportedly has a sodium-ion battery facility in Xuzhou under construction. 

In December, Australian company PowerCap said it would start selling its sodium batteries to clients early this year, which would be 30 per cent cheaper than lithium ion options. 

How to reach parity

Commercialising sodium-ion batteries requires work and a bit of luck, the paper suggests. 

The luck involves lithium prices coming off historic lows to allow sodium to compete. 

The work will be in engineering to fix physical and chemical challenges inherent in sodium batteries. 

Sodium ions are bigger and heavier than lithium ions which means the batteries are less energy-dense than their lithium counterparts, and so require more space and material to store the same amount of charge.

And the main competitor is the lithium iron phosphate chemistry, a less flammable and cheaper version of lithium technology that doesn’t rely on cobalt or nickel. 

That means sodium batteries must compete with the cheapest lithium chemistry on the market – which currently dominates utility scale battery energy storage systems – and do so while being physically larger. 

Without tech breakthroughs soon, the higher cost of materials required by bigger sodium batteries – and these include nickel – would likely limit commercial applications, the paper says.

Simply scaling up production, a tried and true manufacturing technique to bring down prices, won’t do the trick as engineering advances will be needed to deal with some of those challenges.