In recent years, China has made rapid progress in the field of new energy vehicle , especially the field of electric vehicle powered by lithium-ion battery . China is already the country with the largest number of electric vehicles in the world, and this year, the export volume of household cars mainly based on electric vehicles may surpass Germany and become the second in the world. China's BYD company has surpassed the US Tesla and has become the world's largest electric vehicle manufacturer. At the same time, China has also produced electric vehicle battery , which accounts for nearly three-quarters of the world, and is in the world's leading position in battery technology. Driven by the country's policy of promoting the development of military-civilian integration, my country's military-industrial scientific researchers naturally thought of using lithium-ion batteries on submarine .
(Our army's new conventional submarine )
Recently, in the mainland's public scientific research journal "Marine Electrical and Electronic Engineering", researchers from Qingdao Naval Submarine Academy published a paper on the application of lithium-ion batteries on conventional submarines. The article says that lithium-ion batteries can more than double the underwater endurance of conventional submarines and greatly improve the acceleration performance when running at high speed.
(Blade lithium-ion batteries produced by Chinese companies have extremely high security)
As we all know, in the early stages of development, conventional submarines in the world basically used diesel engines to drive generators to charge lead-acid batteries. When sailing underwater, they rely on lead-acid batteries to drive the motor and drive the propeller to rotate. However, diesel engines require air when operating, so conventional submarines must float on the water surface when charging, or extend the snorkel at the depth of periscope , which greatly increases the possibility of exposure and makes the submarine survivability low. In addition, the lead-acid battery has low energy storage capacity, slow charging, weak power output, short life, and may also produce toxic smoke. In contrast, lithium-ion batteries have very excellent energy density, faster charging speed, higher discharge power and longer battery life. However, lithium-ion batteries are not all advantages. Its biggest disadvantage is that they have the risk of thermal runaway and are prone to fires, which is fatal to submarines. An overheated lithium-ion battery may cause thermal runaway failure of the entire battery pack, causing a fire.
(the first ship of the Japanese Big Whale-class "Big Whale")
In the article "Marine Electrical and Electronic Engineering", researchers said that the Chinese electric vehicle industry has found a technical solution to the security problem of lithium ion . The research team found that using low-cost iron and phosphate can replace the common but dangerous combination of nickel and cobalt in lithium-ion batteries, thus improving safety without affecting performance. According to industry data cited by the South China Morning Post, in the Chinese automobile market, the number of electric vehicles using lithium iron phosphate battery technology has exceeded the number of nickel-cobalt batteries. The research team's other safety innovations in submarine lithium-ion batteries include carbon and ceramic coatings for battery packaging.
In fact, Japan and South Korea have begun using lithium-ion batteries on conventional submarines. Japan currently has three conventional submarines using lithium-ion battery technology: the Canglong class "Phoenix Dragon", "Doulong" and the first ship "Big Whale". The second batch of KSS-III diesel-electric attack submarines that were previously launched in South Korea also use lithium-ion batteries. Japan used manganese metal in submarine lithium-ion batteries to improve safety, but paid the price of reduced performance. South Korea still uses lithium-ion batteries containing nickel and cobalt, but adds a lot of other designs to improve safety.
(Korea KSS-III conventional submarine)
At present, some other countries in the world are developing lithium-ion batteries for conventional submarines, including Germany, France and Sweden . This shows that the use of lithium-ion batteries may become a trend to replace "Automatic propulsion systems" (AIP). AIP system is a technology developed in recent decades to improve the underwater navigation performance of conventional submarines, and there are many technical schools.Both my country's latest conventional submarines and Sweden's "Gotland" class use Stirling technology. This technology must carry liquid oxygen, which will also bring safety issues and occupy a considerable amount of space inside the submarine. At the same time, the vibration of the Stirling machine during operation will produce noise, and the submarine needs to add power system sound insulation equipment. The output power of the Stirling engine is also relatively low, and the submarine's navigation speed and acceleration are relatively slow.
In addition, conventional submarines using lithium-ion batteries also have some advantages for nuclear submarine : because it is quieter. Although nuclear submarines have unlimited endurance in theory, nuclear reactor generates heat that can be detected by the enemy, so the cooling pump must be kept running, which may produce some noise. In addition, the wake of nuclear submarines may also contain weak nuclear radiation traces, which can be detected by the enemy using special wake tracking sensors, such as Russia's SOKS system.
Therefore, after the PLA's future new conventional submarines use lithium-ion batteries, they will have greater advantages over US nuclear submarines in the waters around my country.
