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.