With the current energy needs and depletion of fossil-fuel resources, the exploitation of renewable technologies is an essential task. Their intermittence requires reliable and efficient storage systems, as the electrochemical batteries. In the last years, the liquid electrolyte Li-ion battery was considered one of the most important storage technologies, providing high voltage, high energy density and stable cycling performance. Nonetheless, the liquid electrolyte exposes the devices to wear, risks of leakage, dendritic growth and thermal runaway. The scarce availability of Li in the Earth crust is an additional problem. To overcome these issues, the liquid electrolyte can be substituted with a solid one, which guarantees high gravimetric and volumetric energy density, easy transfer of ions, and provides structural and mechanical stability.