Catalytic promotion of transition-metal-doped graphene cathodes in Li-CO₂ batteries

The Li-CO2 battery is a promising energy storage system with impressive theoretical specific energy and discharge capacity. Graphene-based single-atom catalysts (SACs) provide high surface area and long-term electrochemical reactivity and stability, making SACs among the most promising cathode catalysts for these batteries. However, current Li-CO2 systems have high reaction barriers, slowing the reaction and greatly increasing the overpotential. Improvement of the discharge/charge energetics requires atomic-level innovations in cathode design, such as alterations to the catalyst chemical structure. In this paper, we propose enhancing the SAC by using a Ti metal center, which is found to deliver the highest electrochemical Li + CO2 activity among 3d transition metal candidates. Furthermore, we propose cathode surface coating with ionic liquids, since these environments promote the formation of reaction intermediates in the electrochemical conversion process. Our work provides insights to optimize electrode design for high-performance Li-CO2 batteries, which can open new avenues to recycle greenhouse gases and achieve enhanced renewable energy storage. Inputs to calculations, containing all density functional theory calculation parameters, are provided.