Revisiting the Role of Discharge Products in Li-CO2 Batteries.

Abstract

Rechargeable lithium-carbon dioxide (Li-CO2 ) batteries are promising devices for CO2 recycling and energy storage. However, thermodynamically stable and electrically insulating discharge products (DPs) (e.g., Li2 CO3 ) deposited at cathodes require rigorous conditions for completed decomposition, resulting in large recharge polarization and poor battery reversibility. Although progresses have been achieved in cathode design and electrolyte optimization, the significance of DPs is generally underestimated. Therefore, it is necessary to revisit the role of DPs in Li-CO2 batteries to boost overall battery performance. Here, we report for the first time, a critical and systematic review of DPs in Li-CO2 batteries. We appraise fundamentals of reactions for formation and decomposition of DPs and demonstrate impacts on battery performance including, overpotential, capacity and stability, and highlight the necessity of discharge product management. We assess practical in-situ/operando technologies to characterize reaction intermediates and the corresponding DPs for mechanism investigation. Additionally, achievable control measures to boost the decomposition of DPs are evidenced to provide battery design principles and improve the battery performance. Findings from this work will deepen the understanding of electrochemistry of Li-CO2 batteries and promote practical applications. This article is protected by copyright. All rights reserved.