Recent progress in quasi-solid and solid polymer electrolytes for multivalent metal-ion batteries

Abstract

The increasing demand for alternative energy sources has prompted the rapid development of new energy storage technologies. Multivalent ion batteries (MIBs) such as zinc (Zn), calcium (Ca), aluminum (Al), and magnesium (Mg)-ion batteries are promising for large-scale energy storage owing to the abundance and low cost of raw materials. Moreover, the multivalent chemistry of such batteries is of great interest for achieving high-energy-density storage systems. However, some conundrums such as low electrochemical reversibility and sluggish reaction kinetics hinder their practical applications. More importantly, the safety of metal-based batteries is jeopardized by side reactions with the flammable and toxic organic liquid electrolyte, leading to uncontrollable dendrite growth. Recently, quasi-solid and solid polymer electrolytes have attracted intensive interest as safe alternatives to overcome these issues. Herein, we present a comprehensive review of the latest progress of quasi-solid and solid polymer electrolytes applied in multivalent metal-ion batteries including Zn, Ca, Al, and Mg-ion batteries. The synthesis, performance and characteristics of such electrolytes are systematically analyzed. Finally, the remaining challenges and issues faced by MIBs are also summarized. We believe this review will provide a solid foundation for the ongoing and future development of quasi-solid and solid polymer electrolytes towards safer MIBs.