Toward Practical Li–CO₂ Batteries: Mechanisms, Catalysts, and Perspectives

Abstract

Metrics & MoreArticle Recommendations CONSPECTUS: Achieving the target of carbon neutrality has become a pressing global imperative in the world where the imminent threat of greenhouse gas emissions looms large. Metal−CO 2 batteries, which possess dual functions of CO 2 utilization and electrical energy storage, are considered as one of the promising emission reduction strategies. Among varieties of metal− CO 2 batteries, Li−CO 2 batteries have the highest thermodynamic equilibrium potential (∼2.80 V) and the largest theoretical specific energy (∼1880 Wh kg −1 ), making them the center of research efforts and potentially transformational energy storage technologies. However, the development of Li−CO 2 batteries is still in its early stages. The complicated CO 2 reduction and evolution mechanisms have not been fully understood. Widely accepted CO 2 reduction products are Li 2 CO 3 and carbon. These products are produced following a surface-mediated or solution-mediated discharge pathway depending on the adsorption energy of cathode catalysts to intermediates and the solubility of intermediates in electrolytes. During charging, the self-decomposition of Li 2 CO 3 or the reversible codecomposition of Li 2 CO 3 and carbon could occur while applying different catalysts. In addition to the selection of catalysts, the modification of electrolyte components and the control of operation conditions can also affect the reaction processes, contributing to diverse reduction products including Li 2 C 2 O 4 , Li 2 CO 3 and CO, as well as Li 2 O and carbon. Nonetheless, the exact determining factors of controlling reaction routes have been inconclusive. Besides, owing to the intrinsic properties of CO 2 reactants and reduction products as well as the sluggish reaction kinetics at multiphase interfaces, Li−CO 2 batteries are confronted with large overpotentials and undesirable parasitic reactions. Further improvement in battery performance, especially the energy efficiency and cyclic life, is necessary to propel the development of practical Li−CO 2 batteries. In this Account, we summarize our and the community's efforts on the investigation of Li−CO 2 batteries as an attractive avenue toward carbon neutrality. We start with a brief introduction of the physicochemical properties of CO 2 and an in-depth discussion about the fundamental CO 2 reduction and evolution reactions across multiphase interfaces. Then, diverse reaction pathways and underlying affecting factors involving catalysts, electrolytes, and operation conditions are highlighted. Furthermore, enhancement strategies for Li−CO 2 batteries from four aspects of catalyst design, electrolyte modification, anode protection, and external field assistance are presented based on our recent works. At the end of the Account, we provide some potential directions in deepening the understanding of Li−CO 2 batteries, optimizing battery performance, and broadening their application toward future carbon-neutral technologies.

Superoxide Radical Capture Agent for a Stable and Efficient Li-CO2 Battery: Experimental and Density Functional Theory Studies

“…Moreover, CO 2 is employed as the cathode active material of Li-CO 2 batteries, enabling the sequestration of CO 2 and energy release through electrochemical reactions. Accordingly, Li-CO 2 batteries not only facilitate the advancement of high-energy electrochemical energy storage devices but also significantly contribute to address the challenges posed by the energy crisis and climate change. − Nevertheless, Li-CO 2 batteries suffer from two main defects including poor stability and low round-trip efficiency during the discharge/charge processes, which are mainly attributed to the parasitic chemical reactions occurring at the anode, electrolyte, and cathode interfaces. O 2 •– has been found to be the major chemical mediators involved in or promoting the above-mentioned parasitic chemical reactions. , These side reactions lead to larger voltage polarization during discharge/charge processes and affect the cycling stability of batteries …”