Review—Emerging Trends in the Design of Electrolytes for Lithium and Post-Lithium Batteries

More powerful, durable, safer, greener and cheaper batteries are needed to fulfil the compelling requirements of automotive and grid applications. Addressing most of these requirements passes through the development of new-generation electrolytes able to overcome the issues of the state-of-the-art liquid ones, which are based on highly volatile and flammable organic solvents. At the same time, the quest for new electrolytes is strictly related to the attempt of replacing the graphite anode with lithium metal, so opening the way to full exploitation of new post-lithium chemistries, e.g. Li–air and Li–sulfur. Here, we critically review some original concepts which were recently proposed as routes for the development of liquid and quasi-solid electrolytes with improved performances in terms of safety, chemical and electrochemical stability, and capability to sustain high current densities. Attention will be devoted to the problem of lithium dendrites formation, and to the electrolyte families able to eliminate/control their development. Finally, the most promising research directions will be outlined.