Electrode engineering considerations for high energy efficiency Li–CO₂ batteries

Li–CO₂ batteries (LCBs) offer significant potential for high energy storage and efficient CO₂ utilization. However, their practical application is hindered by challenges such as low energy efficiency, poor rate performance, and limited cycle life. To address these issues, it is crucial to develop gas electrodes with a highly conductive, catalytic, and robust network to facilitate rapid and reversible CO₂ conversion. In this work, a comprehensive design for high-performance gas electrodes in LCBs is presented. The critical structure–property relationships of gas electrodes have been investigated with a focus on optimal substrate and catalytic site construction. The developed self-supporting electrodes, featuring ultrafine nanocatalyst decoration within a hierarchical porous and conductive structure, exhibited superior electrochemical performance, including ultrahigh areal capacity (over 10 mA h cm⁻²), excellent reversibility, and high energy efficiency (over 80%) under practical operating conditions. Furthermore, flexible Li–CO₂ pouch cells were successfully fabricated, showing stable operation and high tolerance to mechanical stress, indicating significant potential for large-scale applications in high-energy-density flexible power devices. The principles and guidelines established for gas electrode design are expected to advance the development of superior LCBs and other catalyst-based energy systems.