What are solid state batteries ? According to Samsung, a lithium-ion battery is composed of cathode, anode, separator and electrolyte. A lithium-ion battery applied at smartphones, power tools and EVs uses liquid electrolyte solution. On the other hand, solid state batteries use solid electrolyte, not liquid.  Lithium-ion (Li-ion) batteries, have a separator that keeps cathode and … More Solid State Batteries – Smaller, stronger, and safer