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Study finds Tiamat Na-ion battery well-suited for high-power energy storage applications

Tiamat was founded in 2017 to continue the development and production of Na-ion cell chemistry originally developed by the French research network for electrochemical energy storage (RS2E, Réseau sur le stockage électrochimique de l’énergie) in 2015.

The RS2E/Tiamat chemistry is based on a fluorophosphate Na3V2(PO4)2F3 (NVPF) cathode and hard carbon (HC) anode. Tiamat has introduced high-power cells in both cylindrical and prismatic cell formats.


Similar to other Na-ion cells, an aluminum current collector is used to replace copper foil at the negative electrode, which contributes to a reduced cell material cost. On the pack level, Tiamat has partnered with Plastic Omnium and Startec group to integrate Na-ion cells into modules and packs.

Now, a study by a team from Tiamat and ABB Switzerland has provided an experimental characterization of the commercial Na-ion battery cell developed by Tiamat. Both safety and performance evaluations were performed to offer a full perspective of NVPF/HC-based Na-ion technology and its competitiveness for power applications. The paper is published in the Journal of Power Sources.

The study uses Tiamat Na-ion prototype cells in a cylindrical 18650 cell format (Model NVPF-18650-PP7.1, version 2020). The cell has a weight of ∼34 g and a volume of ∼17 ml. The cell consists of NVPF cathode and HC anode, resulting in a nominal cell voltage of 3.7 V.

The cell has a capacity of 0.61 Ah, a specific energy of 68 Wh/kg, and an energy density of 135 Wh/L at 1C. The cycle life shows 1600 cycles at 5C charge and 5C discharge. More recent cell generations show improved cycle stability; the latest version cell achieves a cycle life of 3200 cycles at 2C charge and 5C discharge.

The cell showed excellent power rate capabilities up to 20C discharge and 10C charge. More than 90% of capacity and >80% of energy (compared to 1C) can still be accessed at 20C discharge.

Safety tests with different abuse conditions (overcharge, external heating, short circuit, and nail penetration) were performed. For all these abuse conditions, the specific cell version showed no thermal runaway.

Thus, the NVPF/HC-based Na-ion technology seems to develop towards a well-suited candidate for high-power energy storage applications.

—He et al.


  • Minglong He, Asmae EL. Mejdoubi, Daniel Chartouni, Mathieu Morcrette, Pirmin Troendle, Roberto Castiglioni (2023) “High power NVPF/HC-based sodium-ion batteries,” Journal of Power Sources, Volume 588, doi: 10.1016/j.jpowsour.2023.233741.



So they are a bit heavy and a bit bulky, but safe.
I wonder how much they'll cost per kwh (when they get production scaled up).
That is really the key.
Probably too heavy for cars, but could work for grid storage and maybe trains.


you can buy similar cells from Alibaba right now (just search for sodium-ion batteries). These also use a vanadium based cathode...price is ~$150/kwh and density is ~100 wh/kg.
There is a guy on youtube testing them, it's they don't catch fire when punctured.

I don't think these vanadium-using cells have much potential, but at least they open a path for sodium-ion batteries.


Electric mobility will be chieper then IC engines once world goes for sodium batteries instead of Lithium. Reliance Industry is verge of bringing that battery to market.


@Nir, The specific energy of 68 Wh/kg is a bit low for mobility applications. If they improve this to current Li battery level (160-250), then they are in business.
Let's see what Reliance come up with.


These cell scream put me in a hybrid. You only need 1-2kwh usable capacity in a Prius/Corolla sized hybrid. The low kwh/kg is meaningless at those pack sizes one overweight passenger would exceed the difference between Lion and these cells two or three to one. Having a 20C discharge capability and extended life is what screams use me in hybrids. Remember the total energy needed to accelerate or decel a Prius sized car to 60mph is only 500 ish what hours total. From 60 to 100 is similar for passing on the highways. Similarly a 20kwh pack would still be light enough to put in a plug-in hybrid for a 40+ mile range before you kick over to the ICE optimized for a single operating point. 3200 x40 is 128,000 miles make the packs modular so when a cell reaches 80% you take that cell or cells out not the whole pack sodium cells will only go down in prices so pack refurbishment shouldn't be a long term issue.


Na3V2(PO4)2F3 is past material development of Valence Technology, finally find a use

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