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French researchers develop sodium-ion battery in 18650 format; performance comparable to Li-ion

Researchers within the RS2E network on electrochemical energy storage (Réseau sur le stockage électrochimique de l’énergie) in France have developed the first sodium-ion battery in an 18650 format. The main advantage of the prototype is that it relies on sodium, an element far more abundant and less costly than lithium.

The energy density of the new Na-ion cell is 90 Wh/kg, a figure comparable with the first lithium-ion batteries; its lifespan exceeds 2,000 care/discharge cycles. The cells are also capable of charging and delivering their energy very rapidly. While numerous other laboratories are also working on Na-ion batteries (e.g., earlier post), none has yet announced the development of such an 18650 prototype.


Six partner laboratories of the RS2E were involved in the project with the goal to find the right composition for the sodium cathode. The development of a future prototype was then entrusted to CEA, a member of the RS2E network. In six months, CEA was able to develop the first sodium-ion prototype in the 18650 form—i.e. a cylinder 18mm in diameter and 65mm in height, the. This should facilitate technology transfer to existing production units.

The project has given rise to a number of CNRS and CEA academic publications and patents. It received financial support from the French Ministry of Higher Education and Research, the CNRS, CEA, the French National Research Agency (ANR) and the Ministry of Defence’s Armament Directorate (DGA), among others.

The next stage of the project is to optimize and increase the reliability of processes with a view to future commercialization.

The RS2E network is headed by Jean-Marie Tarascon, a professor at the Collège de France and Patrice Simon, professor at the Université Toulouse III - Paul Sabatier. RS2E is focused on five main research areas:

  • Advanced Li-ion: dedicated to the Li-ion technology, it will address the remaining locks at the electrode materials, electrolytes and formulation in order to increase their performance, reliability and safety.

  • Capacitive storage:Common research on batteries and supercapacitors including i) the nano-structuration of oxide via ‘template’ approaches, ii) the making of microporous carbon electrodes and iii) the formulation of new electrolytes among which ionic liquids.

  • Eco-compatible storage: it will be dealing with problems of recycling and lifecycle analysis of materials and systems that have been put aside for too long and will prevail the context of sustainable development via i) new concepts of renewable electrodes and ii) the development of innovating syntheses based rather on bio-inspired, biomimetic and/or bio-assisted approaches than on the “green chemistry” precepts.

  • New chemistries: This area includes work on Li-air and Li-S as well as i) Na-ion technology, ii) new systems (Na-D, Redox flow) for the mass storage, and iii) all-solid technology for high temperature stationary applications.

  • Smart materials: The purpose of this thematic is to identify, ensure the chemical functioning and shaping up of materials which, thanks to their redox properties, possess optical, thermo-electrical and modular electrochromic properties; their chemistries are sometimes compatible to design clever bi-functional architectures/shapes (faradic-photovoltaic, faradic-thermo-electric or capacitive-piezo-electric).

“The first application, the most obvious, would be grid storage: storing renewable energy. We are talking about a market as big as the EV market.”
— Jean-Marie Tarascon

Eight partners are involved in the Na-ion battery project, including six RS2E laboratories:

  • The Institut de chimie de la matière condensée de Bordeaux (CNRS)

  • The Laboratoire réactivité et chimie des solides (CNRS/Université de Picardie Jules Verne)

  • The Centre interuniversitaire de recherche et d'ingénierie des matériaux (CNRS/Université de Toulouse III - Paul Sabatier/INP Toulouse)

  • The Laboratoire « Chimie du solide et de l'énergie » (CNRS/UPMC/Collège de France)

  • The Institut Charles Gerhardt Montpellier (CNRS/Université de Montpellier/ENSC Montpellier)

  • The Institut de sciences des matériaux de Mulhouse (CNRS/Université de Haute Alsace)

  • Rosa Palacin, a researcher at the ICMAB (Institut des sciences des matériaux de Barcelone) contributed, alongside these six laboratoires, to the development of the electrolyte of the battery.

  • Liten, a CEA Tech institute.



Energy density, cycle life... NOTHING on the actual charge/discharge rate except a vague "very rapidly" (and I dug for it).

Rate capability is big for apps like hybrid cars.  If you can get 10 C in a 0.9 kWh/kg battery, 20 kg gets you 180 kW of power-handling capability.  That is enough to make hybrids highly desirable and probably the default powertrain option going forward.

As Aha

you missed 0, at 10C they would be 0,9kW/kg


90wh/kg might not sounds very exciting compared to 250wh/kg if best Li-ion but for a first introduction of a new chemistry it is quite a milestone, Na-ion will always be behind Li-ion but still the market opportunities are immense for a battery that is cheap and would offer 150wh/kg

As Aha

I tried to find more info, but 1 paper cites using ruthenium which 100% not compatible with word cheap


Good science but versus a lithium ion battery, saving is gained on replacing Li cation for Na cation, cost wise gain is minimal and as energy density is around half of a typical 18650 Li-Ion were is the gain ????

Thomas Pedersen

Most of you seem to forget that volumetric energy densigy (Wh/l) is more important in electric cars than gravimetric energy density, as opposed to portable electronics.

This is particularly true for hybrid vehicles Where the ICE leaves little 'battery suitable' space left in the vehicles originally designed for ICE's and maximum occupancy space.

It is even more true, because the weight overhead from power converters, cables, motors, cooling circuit, etc. is the same for light and heavy(ier) batteries.


"Most of you seem to forget..."

Not a good way to start a discussion if you want to remain friends with folks on here.


@SJC, I don't think Thomas meant any harm.
He has been on this website for many years (since at least 2012).
He is simply saying that volumetric energy density is as or more important than gravimetric energy density in vehicles.

I think the french were suggesting that these cells would be useful for grid storage.

“the first application, the most obvious, would be grid storage: storing renewable energy […] we are talking about a market as big as the EV market”

And the French will need this if they start shutting their nuclear plants early and replacing them with renewables.

It is tragic to see the country with the lowest CO2 electricity in Europe (excluding perhaps Norway) shutting down their Nukes early. When you have them built and running, you may as well keep them up [IMHO].


For all I care these batteries should be marketed for cellphones and pads. It is so inconvenient to recharge mine and still difficult to store these in my pocket that the cost of 1990s weight may be worth it for sme extra swappable batteries and lower cost. Just dont put the batteries in your pocket.


This is so frustrating. While they compare the sodium 18650's to to iron phosphate lithium cells, but potentially cheaper due to the abundance of sodium, it's pretty fuzzy that they left out so many crucial details. Even so, they do say 2,000 cycles. If we suppose that they have low conversion losses when power makes a round trip in and out of these sodium cells, and that they are cheap in bulk, and therefor attractive for stationary storage...what do they cost per watt hour stored over their lifetime? Ok, researchers can only estimate costs in bulk, but that's ultimately what will make these successful or not, since they will always be behind lithium on the mobile priorities.


As ultimate clean energy sources (solar and wind?) are interruptible, much larger lower cost multiple megawatts + multiple cycles storage units are required.

Current first generation (1 to 20 megawatt-hours) battery storage units will soon be replaced by 2nd and 3rd generation higher performance units of up to 100 megawatt-hours.

Fixed e-storage units do not have to have the same high energy density as mobile units.


One year later, and there is no more major publications about the sodium 18650. The thing is, I check Google News every day for articles about these batteries and lithium-ion.

You can apply the 80/20 rule here. 80% of the news will be about battery breakthroughs that don't come to fruition and the ones that see production are a decade or more away.

I am still optimistic though, there will be something that surpasses lithium-ion. Like lithium air, or these sodium batteries...

Right now typical 18650 batteries last about 500 charge cycles. That is, they reach 80% of their original capacity (difference between beginning capacity and current). No where does this article actually define what their cycle life is.

The definitions continue to be ambiguous (as other posters mentioned) for just about everything else.

So yeah, confirmed fluff. Scientists need PR too!

Battery Bro - What is an 18650 battery?

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