Today I came across an article about Altech Batteries Limited’s Sodium Chloride Solid State (SCSS) Battery. So I also went to their website and it sounded very interesting until I got to this statement:

The battery plant will produce 1,666 battery packs per annum, rated at 60 KWh each. These CERENERGY® modules are expected to sell for between EUR 700-900 per KWh.

First of all, I think sodium ion batteries are a great match for grid storage: The models available in China right now have slightly lower energy density (in kWh/kg or kWh/l) than LFP or NMC lithium ion batteries, but that is largely irrelevant for stationary applications such as renewable energy storage or grid stabilisation, where specific cost ($/kWh) is more important.

Like LFP batteries, sodium ion batteries do not us Cobalt, a mineral mostly mined in the Democratic Republic of Congo. About 1/5 of production there is from artisanal miners, where child labour and other abuses are common.
Unlike LFP, sodium ion doesn’t use graphite or lithium. By doing without these ingredients and instead using cheaper equivalents such as sodium instead of lithium, iron instead of cobalt and nickel, etc. costs can be lower. As Auke Hoekstra wrote on Twitter on 2024-05-24:

Cheap batteries are a GAME CHANGER for
GRID CONGESTION and for SOLAR and WIND

We are now moving towards $60 on the cell level for LFP and $40/kWh for sodium ion.

Admittedly, there is a bit of a gap between prices at the cell level and the pack level (built from interconnected cells in a case), but almost a year ago, BloombergNEF already reported that:

The price of lithium-ion battery packs has dropped 14% to a record low of $139/kWh (…)
(“BloombergNEF’s annual battery price survey finds a 14% drop from 2022 to 2023”, 2023-11-27)

Read that again and then look at Cerenergy’s promise of offering similar technology at $770-990/kWh. The lower end of that range is the average pack level price that BloombergNEF listed for the year 2013, eleven years ago.

Yes, Cerenergy is solid state instead of liquid electrolyte, but that’s the only significant difference other than a price that’s an order of a magnitude higher, probably due to the high cost of the solid state electrolyte, but also the use of nickel instead of iron-based cathodes that current sodium ion batteries tend to use.

When others tout solid state technology for batteries (i.e. batteries without liquid electrolyte), the main selling point tends to be higher energy density per kg, which is still important for EVs, especially in locations with a not very dense charging network. However, when targeting the grid storage market, this benefit becomes irrelevant: Nobody really cares if some shipping containers full of batteries installed next to an electricity substation weigh 6t each or 10t each. However, it makes a huge difference if they cost $80,000 each or $800,000 each because it means you can install 10 MWh of storage with cheaper technology for the price of 1 MWh with the more expensive option. That’s a game changer!

Perhaps I am missing something in this picture, but I am yet to be convinced of the clear benefit of more expensive solid state batteries over low cost conventional chemistry batteries for the bulk of the market, both for lithium and for sodium chemistries, and I don’t see how that will change any time soon.

There may be a market for solid state lithium batteries for niche markets such as electric airplanes, but it’s simply going to be too expensive for grid storage or for most of the EV market for the foreseeable future.