Challenges and Opportunities for Multivalent Metal Anodes in Rechargeable Batteries

Lithium metal has been deemed the Holy Grail anode for next-generation,high-energy-density metal batteries. However, severe challenges in abundance, cost, and safety concerns have greatly hindered the practical use of Li metal anodes. Alternatively, multivalent metal anodes (Zn, Mg, Ca, Al, etc.) with less reactivity and much higher natural abundance are urgently summoned and increasingly investigated in recent years. The technologies for using multivalent metal anodes are not mature and are still in their infancy for practical applications. To comprehensively understand the challenges and opportunities for multivalent metal anodes, the fundamental mechanism and key issues are discussed here in detail, including electrolytes for reversible anode plating/stripping, notorious surface passivation, dendrite formation, and anode corrosion. Strategies for tackling these issues are summarized. A general perspective and future research directions are also presented in this review. It is expected that this review will provide a promising opportunity for newly emerging multivalent metal anodes and pave the way for next-generation high-energy-density metal batteries.