Discharge product chemistry of Li-CO2 batteries: reversibility challenges, reaction pathways and regulation strategies.

As part of global efforts to mitigate climate change, metal-CO2 batteries offer a new pathway for achieving closed-loop carbon cycling and enabling a low-carbon economy through CO2 capture and conversion. Among these, Li-CO2 batteries have attracted considerable attention due to their high theoretical energy density and environmental friendliness. However, their practical application is often constrained by the thermodynamic stability, kinetic inertness, and insulating nature of the discharge product Li2CO3, which result in high charge overpotentials and poor reversibility. These challenges also trigger cascading issues such as electrolyte decomposition and catalyst corrosion, severely compromising battery lifespan and cycling stability. In response to these bottlenecks, this review systematically outlines the working principles and key scientific challenges of Li-CO2 batteries, with a focus on analyzing the formation mechanisms of discharge products and their impact on reversibility. Furthermore, it summarizes recent research advances and regulatory strategies in catalyst design, reaction pathway modulation, and product morphology optimization. On this basis, future directions for the development of high-specific-energy, long-life, and highly reversible Li-CO2 batteries are proposed, aiming to provide theoretical foundations and technical insights to support further research in this field.