After two years of research, RS2E, a French research network of RS2E manufacturers and researchers, has unveiled the first sodium-ion battery prototype.
This battery could easily be industrialized using the same production processes as the lithium-ion batteries that power laptop computers, tablets and electric vehicles.

Although less effective in terms of its performance, this lithium-ion battery-based technology could be a cheaper alternative for mass storage of renewable energies. For example, the battery in the Tesla electric car is no more than the combination of several thousands of 18650 lithium-ion batteries.

Source : http://www.industrie-techno.com/une-batterie-sodium-ion-devoilee-par-un-reseau-d-industriels-et-d-academiques-francais.41391