According to UDT Asia, Japan will soon have the advanced Soryu we could have had with all Lithium batteries I recollect:The biggest issue IMO is getting the subs quickly enough. My personal opinion is we should be cutting steel at about now.
We are going to have life extend Collins IMO.
Any chance we could get a short lease on some Rubis submarines as they are coming offline?
IMO Lead acid will have to make out some of the batteries for some of the class, as I am not sure lithium is tooled up/cheap enough/proven enough/low fire risk enough for an all lithium boat. You don't have to replace all of your battery with lithium ion. I'm not even sure anyone has an all lithium boat on the design boards.
https://www.shephardmedia.com/news/defence-notes/udt-asia-japan-boosts-submarine-technologies/