Bromide-mediated membraneless electrosynthesis of ethylene carbonate from CO₂ and ethylene

Cyclic carbonates, such as ethylene carbonate, are crucial in various applications, including lithium-ion batteries and polymers. Traditional production routes for ethylene carbonate rely on high-temperature thermocatalytic processes that use fossil-fuel-derived epoxides and carbon dioxide (CO₂). Herein, we report a bromide-mediated membraneless electrosynthesis strategy for direction conversion of ethylene and CO₂ into ethylene carbonate. This method leverages electrolyte engineering to modulate the kinetics of solution chemistry to proceed at rates that match the high-current bromide electrooxidation, and cathode protection with chromium hydroxide film to suppress the parasitic bromine reduction reaction. These enable the system to operate at 10-250 mA/cm² current density with 47-78% Faraday efficiency towards ethylene carbonate. The system's practicality is underscored by achieving an ethylene carbonate product concentration of 0.86 M and maintaining stability for over 500 hours. Furthermore, we demonstrate the integration of this process with CO₂ electroreduction to ethylene, enabling a cascade ethylene carbonate electrosynthesis using only CO₂ and water as feedstocks. A comprehensive techno-economic analysis confirms the strong economic potential of this method for future applications.