Next generation electrolytes for sodium ion battery

Abstract

The objective of this thesis is to develop more stable and safer electrolytes based on ionic liquid (IL) solvent for sodium ion batteries (SIBs). In this work, the comprehensive study on ionic liquid electrolyte for SIBs are presented on the aspect of electrochemical stability, thermal stability and high-voltage application. First, the effect of sodium conducting salts in IL electrolyte on the cyclability of Na0.6Mn0.9Co0.1O2 half-cell and the formation of electrode-electrolyte interphases were investigated. Following, the relation of anion core structures, functional groups and cations to essential physicochemical properties had been drawn. For thermal safety, IL-based full cell Na0.6Mn0.9Co0.1O2/Na2.55V6O16 is capable to operate at elevated temperature and safer than organic-based cell in calorimetry tests with lower onset temperature and self-heating rate. Finally, ether-functionalize ILs were characterized in detail for high-voltage application. The difference in cycling stability was observed as a result of cation core-structure effect to the stability of Na-electrolyte interphase.