Progress in solid-state high voltage lithium-ion battery electrolytes

Abstract

• Five major class of electrolytes for high voltage batteries reviewed. • Future trends and opportunities on solid Li-ion cells analyzed. • Operating voltage window and Li+ conductivity of key materials are compared and summarized. Developing high specific energy Lithium-ion (Li-ion) batteries is of vital importance to boost the production of efficient electric vehicles able to meet the customers’ expectation related to the electric range of the vehicle. One possible pathway to high specific energy is to increase the operating voltage of the Li-ion cell. Cathode materials enabling operation above 4.2 V are available. The stability of the positive electrode-electrolyte interface is still the main bottleneck to develop high voltage cells. Moreover, important research efforts are devoted to the substitution of graphite anodes with Li metal: this would improve the energy density of the cell dramatically. The use of metallic lithium is prevented by the dendrite growth during charge, with consequent safety problems. To suppress the formation of dendrites solid-state electrolytes are considered the most promising approach. For these reasons the present review summarizes the most recent research efforts in the field of high voltage solid-state electrolytes for high energy density Li-ion cells.