Nikkei Technology Online has reported Sony's plans to increase energy density per volume by 40% from the current 700Wh/L to 1,000Wh/L by using a sulfur compound as an electrode material. Compared with an existing battery having the same volume, the new batteries are claimed to increase battery life by 40%.
Sony is aiming to exploit the large capacity of the batteries and have them employed for various devices including mobile devices and robots.
Aiming at commercialization in 2020, Sony is developing a lithium-sulfur (Li-S) battery and magnesium-sulfur (Mg-S) battery. The Li-S battery uses a sulfur compound for the positive electrode and metal lithium for the negative electrode. Though the sulfur-based positive electrode has a low voltage, the theoretical value of its current capacity per electrode weight is high, potentially realizing a battery cell with an energy density higher than 1,000Wh/L.
Metal lithium will be used for the negative electrode.
When metal lithium is used for a rechargeable battery, the battery generates dendrites at its negative electrode as it is repeatedly charged and discharged. If the dendrites cause a short circuit by breaking through the separator that insulates the positive electrode from the negative electrode, it can cause heat generation or
ignition. This problem has not been solved yet.
Despite such difficulties, Sony considers that it is a promising technology to realize an energy density of 1,000Wh/L in about 2020. Manufacturers other than Sony are
also actively engaged in the development of batteries using sulfur as an electrode material. So, major manufactures will probably compete against one another in the
commercialization of such batteries.
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