Rechargeable Mg–CO2 battery: A new system for sustainable energy and carbon management

Mg–CO 2 batteries are emerging electrochemical systems that couple magnesium metal chemistry with CO 2 cathodic reactions, offering a distinctive platform for simultaneous energy storage and carbon utilization. This perspective critically examines their fundamental composition and operating principles, highlights intrinsic advantages such as magnesium abundance, multielectron redox chemistry, and high theoretical energy density, and analyzes the key challenges that currently limit their development, including sluggish CO 2 reduction kinetics, poor reversibility associated with thermodynamically stable carbonate-based discharge products, severe interfacial passivation, and incomplete mechanistic understanding. We then trace the evolution of Mg–CO 2 battery research, emphasizing how advances in catalyst design, electronic-structure modulation, defect engineering, and electrolyte regulation have progressively enabled reaction-pathway control and reshaped discharge product chemistry. Building on these advances, potential application scenarios of Mg–CO 2 batteries are discussed, highlighting both near-term opportunities and long-term prospects. Finally, this perspective underscores the necessity of moving beyond empirical performance optimization toward mechanism-guided design and rational control of reaction pathways to enable durable and practically relevant Mg–CO 2 battery technologies. • Mg–CO 2 batteries uniquely integrate multivalent Mg chemistry with CO 2 electroconversion, offering high theoretical energy density and intrinsic safety. • Poor reversibility, dominated by the sluggish decomposition of thermodynamically stable MgCO 3 , remains the central scientific bottleneck. • Recent advances in catalyst design, electronic-structure modulation, defect engineering, and electrolyte regulation enable reaction-pathway control. • Mechanism-guided strategies are essential to transition Mg–CO 2 batteries from empirical optimization toward durable and practical technologies.