Dual-Site Ni Nanoparticles-Ru Clusters Anchored on Hierarchical Carbon with Decoupled Gas and Ion Diffusion Channels Enabling Low-Overpotential, Highly Stable Li-CO₂ Batteries

Li-CO₂ batteries present an innovative electrochemical approach, integrating CO₂ capture and energy storage. Nevertheless, slow CO₂ reduction and evolution reaction kinetics lead to substantial overpotentials and limited cycling lifespans. This study introduces a hierarchical gas electrode derived from wood, functionalized with nickel nanoparticles and ruthenium clusters. The three dimensional (3D) hierarchical porous structure serves dual purposes: 1) It provides separate channels for gas and ion diffusion, enhancing transport kinetics during Li-CO₂ redox reactions. 2) It offers ample space for discharge product deposition, mitigating surface passivation. Furthermore, the dual-site Ni–Ru active centers enhance the co-oxidation reversibility of Li₂CO₃-C aggregates through electronic structure optimization. This suppresses electrolyte decomposition and side reactions, especially at high current rates. These advantageous structural features enable Li-CO₂ batteries with optimized cathodes to achieve: 1) A discharge platform below 3.16 V, 2) An ultralow discharge–charge overpotential gap of 0.619 V, 3) A full discharge capacity of 34.681 mAh cm⁻², and 4) A long cycle life exceeding 1100 cycles (2200 h). This study presents an effective design strategy that combines electrode architecture and metal catalytic centers for gas cathodes. The findings advance the development of aprotic Li-CO₂ batteries as a viable electrochemical energy storage solution.