Advances and Challenges in High-temperature Electrochemical CO2 Conversion Technology

Abstract

During the past century, CO₂ emissions around the world have continue to grow at an astonishing rate. In recent years, with the proposal of the global goal of “carbon neutralization”, high-temperature CO₂ electrolysis technology based on solid oxide electrolysis cell (SOEC) has ushered in a rapid development opportunity. SOECs operating at elevated temperatures can not only make full use of industrial waste heat but also convert CO₂ into hydrocarbon fuels or high-value-added chemical products via electrochemical reactions. Currently, multiple countries around the world have deployed various high-temperature electrochemical CO₂ conversion projects. In 2017, Haldor Topsøe A/S (Denmark) reported the world’s first commercial CO₂ electrolysis system, which can produce CO gas through SOEC electrolysis of CO₂, with a production capacity of up to 10 Nm³ CO₂/h. In 2019, Sunfire GmbH (German) developed a high-temperature co-electrolysis demonstration system which can product syngas at 4 Nm³/h rate. In 2020, the University of Aarhus (Denmark) reported a CO₂ methanation reactor based on SOEC, which can upgrade biogas to pipeline mass methane in a 10 Nm³/h experimental device. Compared to the high-temperature water electrolysis for hydrogen production, the scale of the high-temperature CO₂ electrolysis device is relatively small. With the increasing demand for energy density and power density of CO₂ conversion devices in various new application fields, further research and development is necessary to overcome the challenges of high cost and low durability in large-scale application and commercialization.