The search for solid electrolytes enabling safer, more energy dense all-solid-state-batteries has led to the revival of sulfide glass-ceramics. As such, LiPxSy have been highly touted for their high ionic conductivity. Aliovalent doping has been explored extensively to improve further the ionic conductivity, and more importantly the interphase stability between the electrolyte and electrode. In this talk, I will discuss a few (new) important design principles for superionic conductors in all solid-state batteries, in pursuit of practically viable all-solid-state batteries. On the other hand, the quest for novel electrolytes has led us to explore unexpected candidates for fast ion transport. We explored the use of liquefied gas electrolyte systems exclusively composed of solvents that are gaseous at room temperature and atmospheric pressure in rechargeable energy storage systems. We will discuss the latest discovery on using difluoromethane and fluoromethane in rechargeable lithium metal batteries with good cyclability of a high voltage lithium transition oxide cathode operated at as low as –80°C, with excellent capacity retention.