Multifunctional Quasi-Homogeneous Catalysts as a New Catalytic Strategy to Boost the Performance of Li-O2 Batteries.

Li-O2 batteries have been considered as a kind of prospective next-generation batteries due to their ultrahigh energy densities. However, limited capacities, high charge overpotentials, and short lifetime are troubling obstacles for realizing their real-world implementation. Common strategies, including introducing solid-state catalysts (SSCs) and redox mediators (RMs), are insufficient to solve these issues. Herein, Ru-loaded amino-phenanthroline-based carbonized polymer dots (RuApCPDs) integrating the catalytic activity of SSCs with the mobility of RMs have been designed to behave as quasi-homogeneous catalysts in the electrolyte. Their mobile nature can ensure the avoidance of complete coverage of active sites, and the catalytic ability decreases the charge overpotential through co-deposition with the discharge products. Additionally, the RuApCPDs can also adjust the Li+ solvation structure and well protect the Li metal anodes with high stability. As a result, the introduction of RuApCPDs leads to a fivefold increase in discharge capacity, a low charge voltage of 3.75 V, and a running life of 168 cycles (79 cycles without RuApCPDs). The multifunctional quasi-homogeneous catalyst developed here demonstrates its advantageous potential as a new catalytic strategy for bringing Li-O2 batteries to become a viable technology.