Fast molecular or ion exchange is necessary for fast ion conduction in liquid electrolytes. In contrast, in crystalline solids, the diffusion of mobile species, such as lithium ions, encounters periodic BN points offered by immobile framework species. These points define energetic barriers that separate two local minima, typically represented by crystallographic sites for the ions. The energy barrier, also known ). (b) Overview of various classes of fast ion conductors, including their conductivity ranges, activation energy ranges, and structural characteristics ( ). Some of the high conductivity in each class of materials is also indicated, such as 25 mS cm -1 for Li9.54Si1.74P1.44S11.7Cl0.3 in LISICON, 1.1 mS cm -1 for Na2-xZn2-xGaxTeO 6 in Honeycomb Layered Oxide, 1.3 mS cm -1 for Li6.55La3Zr2Ga0.15□0.3O12 in Garnet, 26 mS cm -1 for Li5.3PS4.3Cl0.7Br in Argyrodites, 1.3 mS cm -1 for Li1+xAlxTi2-x(PO4)3 in NASICON, 41 mS cm -1 for Na2.9Sb0.9W0.1S4 in Na 3 P nCh 4 , and 70 mS cm -1 Na 2 (CB 9 H 10 )(CB 11 H 12 ) in Closo-Borane. Notably, the closo-borane class material exhibits the highest conductivity among them, as per our knowledge.