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SOLiTHOR and Sonaca partner to advance the electrification of regional aircraft and urban air mobility; solid-state Li batteries

Belgian solid-state Lithium battery technology company SOLiTHOR and aerospace company Sonaca signed a bilateral Memorandum of Agreement jointly to develop safe, high-density rechargeable solid-state Lithium battery systems for Regional Aircraft and Urban Air Mobility. This partnership will also expand to satellite systems as well as defense systems.

This alliance will divide key activities in the research, development, production and integration of cells and battery systems designed for powering aircraft.

SOLiTHOR will be responsible for cell research, development, testing characterization, format design and production of 10Ah-40Ah cells. Sonaca will develop the battery packaging including all related management systems. It will also certify the battery system.

The cells will be produced and manufactured by SOLiTHOR in Sint-Truiden, Flanders, Belgium and the integration of the aircraft battery systems will take place at Sonaca’s plant in Charleroi, Wallonia, Belgium.

SOLiTHOR and Sonaca believe that their complementary capabilities will provide the greatest advancements in solid-state Lithium battery systems technologies for all regional aircraft and urban air mobility applications.



There was a deeply interesting comment here recently, which I have mislaid, noting that there is a weight increase in at least some types(?) of lithium batteries ( solid state only?)

This as was noted has considerable implications for their use in aircraft, as an aeroplane normally is way lighter when cruising and landing than on take off as there is less fuel.

At least some types (?) of battery are going to put on weight, which has particular implications for eVTOL, as they use shed loads of power landing as well as taking off.

Anyone car to bring a glimmer of light to my deep ignorance?

All batteries, or just lithium?

Or just solid state?

How much, and how much of a problem?


I've tracked down the reference here.
It was a comment by the redoubtable sd here:


' Lithium air will do even better except for one small (or maybe not so small) problem that no one seems to mention. When you burn gas or diesel or even hydrogen, the weight of the fuel decreases while with a battery , the weight stays the same. With lithium air, as energy is generated the battery gains a drastic amount of weight. The reaction is 2 Lithium + 1 Oxygen > Li2O. Lithium has an atomic weight of 3 while Oxygen has an atomic weight of 16 so if you start with a thousand kg of Lithium, you end up with 3667'


' a lithium air battery that starts with 1000 lbs of lithium, you end up with 3667 lbs of lithium oxide (6 + 16 = 22 and 22/6 = 3.667). Possible for trucks but a real problem for aircraft. '

Will anyone expand upon and contextualise that?




Any of the air batteries, lithium air, aluminum air, zinc air, etc has this problem. You are combining the metal with air to make an oxide which has the combined weight of the metal plus all of the air. This would also be true for hydrogen fuel cells except that the resulting water does not have that much value so it is generally discarded. H2 has a molecular weight of 2 but H2O has a molecular weight of 18 so the resulting water from a fuel cell weighs 9 times that of the hydrogen consumed. Again, this would be true for any combustion engine if you needed to keep the resulting H2O and CO2 but generally those are exhausted.


I should have said that the oxide has the combined weight of the metal plus the oxygen consumed. About 79% of air is nitrogen which just passes through the metal air battery, fuel cell or engine.


Thanks sd.

I just had a look at lithium sulphur batteries for flight, but Oxis technologies which was leading on them went kaput.

The concern for fuel cells is contrails, although they do not omit the other stuff that jet engines do:

' Aircraft engines emit a variety of combustion products including 3.16 kg of carbon dioxide (CO2) and about 1.23 kg of water vapour (H2O) for every kg of fuel burned'


Hydrogen has around 3 times the energy density per kg as jet fuel, but I am getting a bit above my pay grade in trying to work out how much more water vapour it produces compared to kerosene in a jet engine, and presumably there are different figures for burning hydrogen in a jet engine and using it in a fuel cell, as they would have, I would have thought, different efficiencies.

It is clear though that additional weight is far less of a problem than for lithium air etc, with remaining issues ( in this respect, not umpteen other challenges like storing the hydrogen at high density ) confined to water vapour in the contrails.

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