Improved Performances of Sodium-Sulfur Battery via in-situ Electrochemical SEI Formation Technique

Abstract

Improved Performances of Sodium-Sulfur Battery via in-situ Electrochemical SEI Formation Technique Hwonki Lee, KwangSup Eom SMSE, Gwangju Institute of Science and Technology, 123 Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Korea hwonkilee@gist.ac.kr Lithium ion batteries are the presently predominant energy storage systems for portable electronic devices and electric vehicles (EVs). Although lithium ion batteries are suitable for small-scaled applications, they are inappropriate for large-scaled stationary energy storage storage called ESS in terms of cost. Therefore, new battery for ESS that is cheaper and has a higher capacity than a lithium ion battery is needed [1]. Specifically, a room temperature sodium-sulfur battery (RT-NaS) is receiving attention due to its high theoretical capacity of 1675 mAh g-1. This system also has the advantages of being cost-effective and resource-abundant. However, most of the RT-NaS batteries showed the low initial reversible capacity and fast capacity fade during cycling [2]. It is because the intermediate product of long chain polysulfide easily dissolves into the electrolyte. During the charging/discharging process, polysulfides diffuse between the anode and the cathode through a polymer membrane, and then gradually reduce coulomb efficiency (called Shuttle Effect). Therefore, in order to improve stability of RT-NaS, it is necessary to impede a continuous dissolution of polysulfides. In this presentation, we will introduce a new method to restrain the polysulfide dissolution by artificially forming protective solid electrolyte interphase (SEI) on the surface of cathode using in-situ electrochemical method. It could simultaneously increase the initial capacity and stability of RT-NaS battery more than two times. References 1 M. Armand and J. M. Tarascon, Nature, 2008, 451, 652＆ndash;657. 2 Y. X. Wang, et al., Adv. Energy Mater., 2017, 1602829, 1＆ndash;17.