Quasi-solid sodium ions electrolyte of system hydrated glass

Na2O−B2O3−SiO2−H2O system hydrated glass with Tg ranges from −10 to 150◦C is synthesized by aqueous chemical methods and is applied to symmetrical cells as quasi-solid electrolyte. At the temperature around Tg, the solid state transforms to quasi-solid state, whose mechanical property keeps like gel electrolyte, but the conductivity leaps from 5.31 × 10−6 S cm−1 to 5.43 × 10−3 S cm−1, much higher than most of the glass–ceramic electrolytes. As most of the solvated water is evaporated, H2O left in the system distributes in the intervals as hydroxyl, which is much benefit to the ions transportation, and more important is to increase the voltage window to 2.24 V and even higher. The cycle performance is also researched. After 1000 circulations, there is still 65% capacity retention and no obvious damage is discovered in the electrolyte, which means much better cycle property of the electrolyte than gel electrolyte. Other compositions in the quasi-solid system including different contents of B2O3, Na2SO4 and m in sodium silicate NaO2·mSiO2 are also studied. In general, quasi-solid Na2O−B2O3−SiO2−H2O system owns better conductivity and cycle performance than most glass–ceramic solid electrolyte, and it is environment-friendly, inexpensive and practical to be used as sodium ions quasi-solid