Assessing the Performance of Cobalt Phthalocyanine Nanoflakes as Molecular Catalysts for Li-Promoted Oxalate Formation in Li–CO2–Oxalate Batteries

• Published in: Journal of physical chemistry. C 2018-11, Vol.122 (45), p.25776-25784
• Main Authors: Goodarzi, Moein, Nazari, Fariba, Illas, Francesc
• Format: Article
• Language: English
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.8b06395

Removal of O2 molecules from the cathode environment in the Li-based battery has led to introduction of the Li–CO2 battery as the novel and promising source of energy storage. In spite of CO2 capture through the reversible reaction between Li atoms and CO2 molecules at the cathode, the performance of the Li–CO2 battery is hampered by formation of the Li2CO3 insulating product in the discharge process and its difficult decomposition in the charging process. Hereby, we explore the possible improvement of the performance of the Li–CO2 battery through replacement of Li2CO3 by Li2C2O4 as the discharge product. This is achieved by systematic addition of Li and CO2 to a cobalt phthalocyanine (CoPc) nanoflake employed as the molecular catalyst in the cathode of the Li–CO2 battery by means of computational density functional theory-based methods. The present results predict high adsorption energy of the CO2 molecules (−2.16 eV), low Li-intercalation voltage (1.45 V), reveal the important and constructive influence of the electrolyte (dimethyl sulfoxide) on the adsorption and decomposition energies and Li-intercalation voltage, and suggest a through-space electron transfer mechanism for the formation of the Li2C2O4 product on the CoPc nanoflake. Moreover, the high electron affinity of the CoPc nanoflake along with the suitable thermodynamics and kinetics of electron transfer from the CoPc nanoflake to the CO2 molecules during the formation of the Li2C2O4 product confirm the potential abilities of the CoPc nanoflake to be used in the Li–CO2 battery. Therefore, present results provide a sound assessment of the capability of the CoPc nanoflake as a cathode material in the Li–CO2 battery and show that this provides a possible and effective solution to improve the performance of the Li–CO2 battery and to introduce new Li–CO2–oxalate batteries.