Highly dispersed RuCo clusters on N-doped carbon shell for Li–O2/CO2 batteries and exploitation of the synergistic effect of O2 and CO2

Abstract

Li–O₂/CO₂ batteries are of central importance for environmentally friendly energy technologies. However, the battery performance still needs to be improved, while the factors affecting the battery capacity are still ambiguous. Herein, we directly synthesized a series of N-doped carbon shell-encapsulated RuCo clusters to improve the battery performance as well as to deeply investigate the catalytic mechanism. Due to the porous structure and evenly dispersed RuCo alloy, the obtained Li–O₂/CO₂ battery showed excellent discharge and charge performance as well as a long-time cyclic stability of 550 h and 560 cycles. In addition, the catalytic pathway was verified by comparing the discharge voltage of Li–O₂ and Li–O₂/CO₂, which confirmed the route of 4Li⁺ + O₂ + 2CO₂ + 4e⁻ = 2Li₂CO₃. To evaluate the effects of O₂ during the discharge process, the catalytic kinetics and battery capacity were verified by monitoring the capacity–current rate–O₂ content relationship. In conclusion, the capacity of Li–O₂/CO₂ batteries relies on a balance of both the discharge current and O₂-diffusion rate as well as the crystallization process of Li₂CO₃.