Japan will likely become the first country in the world to equip diesel-electric submarines with lithium-ion batteries. GS Yuasa, a Kyoto-based developer and manufacturer of battery systems, said in a 21 February press statement that such batteries will be mounted on two Soryu-class boats currently in build for the Japan Maritime Self-Defense Force (JMSDF).
According to Jane's Fighting Ships, eight Soryu-class boats are currently in service with the JMSDF.
Four others are currently under construction, two of which, SS 511 and SS 512, are expected to be commissioned in 2020 and 2021 respectively, and will be fitted with lithium-ion batteries in place of lead-acid batteries and a Stirling air-independent propulsion (AIP) system.
"At this moment Japanese submarines use lead-acid batteries as a source of power, but submarines being produced since the fiscal year 2015 will use lithium-ion batteries instead," said the company.
GS Yuasa said it will start producing the batteries for the two boats in a special factory in Shiga Prefecture in March 2017, with deliveries expected to begin in August 2018.
GS Yuasa said it started developing lithium-ion batteries for submarines in the 1990s. In the first half of 2000s the company joined a research and development project by Japan's Ministry of Defense and Mitsubishi Heavy Industries.
There is speculation within Japanese military circles that GS Yuasa will also provide lithium-ion batteries for a new (post-Soryu) class submarine. A GS Yuasa spokesperson declined to comment on the matter.
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