If lithium batteries are used, I would guess it is lithium iron phosphate battery (LFP). It is safe and mature technology, and China has a big production capacity meaning experience. It is already about 170 WH/Kg today. Going for Li-ion is suicidal IMO.
So basically we have no way of knowing how many 039 subs have been launched in the last 9 years or so?
Variants wise, there have been 4 different variants observed since then, but it doesn't sound likely there was just one boat made of each of those variants.
The paper's list seems like it could be the very bottom projection of numbers, since it bases it's 4 subs after the year 2013 on the number of different observed modifications of various yuan subs.
I’m not an expert in Chemistry but doesn’t sodium react explosively to water? Do we know that Sodium Ion batteries are safe? If not I’m not sure if it’s wise to put them in an submersible vessel?"He describes this submarine as possibly or speculatively using lithium ion batteries"
I've read the same rumor here and there
The big question is that when we talk about lithium batteries we can be talking about batteries with a density of 200-260 watt hours / kilo (example: the batteries of Tesla cars) ...
Or on the other hand we may be talking about safer batteries suitable for a Submarine and about 100 Watt hours / kilo, which I suspect could be the case for the last three Japanese submarines or not, it is difficult to know; but the question of the safety or rather dangerousness of higher density Lithium batteries is a real problem in a submarine
But within two years, in 2023, there will be 200 Watt-hour/kg sodium batteries.
This is incredible, and could be a revolution in the diesel-electric submarine.
I don't know
The amazing thing about this story is that Captain Nemo's Submarine dreamed up by Jules Verne ... carried ...
I’m not an expert in Chemistry but doesn’t sodium react explosively to water? Do we know that Sodium Ion batteries are safe? If not I’m not sure if it’s wise to put them in an submersible vessel?