Submarine Lithium batteries may be safer than Lead-acid

Below this article, on February 8, 2021 Anonymous has kindly commented:

Usually, the condition and performance of batteries are monitored. Batteries are exchanged on a regular basis and/or according to degree of deterioration [1] and never used over the service life of a submarine (20-30 years) [2]. One of reasons for adoption of Lithium-ion Batteries (LIBs) are LIBs’ safety [3, 4].

[1] The replacement period for Lead-acid Batteries (LABs) is decided based on operational experience (eg. once every three-years). LIBs might be exchanged once every six-years.

[2] Poorly managed or deteriorated LABs generate flammable hydrogen gas which might cause a hydrogen explosion as shown in the case of ARA San Juan which sank and imploded in 2017.

[3] TKMS might rely on Siemens' patent LIBs [or SAFT LIBs - see this article.]

[4] Possible serious accidents caused from LABs and LIBs are hydrogen explosion and fire, respectively. LIB cells on subs and surface ships/boats are increasingly shielded with inert gas in case of fire (in line with the Japanese standard for marine LIBs).
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Separately Japan's large GS Yuasa Lithium-ion battery making company: 

A. Makes Lithium batteries for Industrial and Military customers (called "LIMs") and

B.  Has made Lithium batteries for unmanned and manned undersea vessels "without incident to date".

Combining A + B = GS Yuasa makes Lithium batteries for military manned submarines.

This article says it more plainly: GS Yuasa is making LIBs for the latest Japanese submarines specifically the Soryu Mk 2s and new Taigei class - see SORYU TABLE.

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PETE COMMENT

It will take 10+ years of incident-free, safe LIB operation on Japanese submarines to fully assess whether LIBs are safe or safer than LABs.