Lithium-Rich Oxygen Batteries with Low Metal Loading Based on Iridium Single-Atom Electrocatalysts

Abstract

Isolated single-atom catalysts (SACs) are famous for their exceptional catalytic characteristics. Developing single-atom catalysts provides a maximum atom utilization efficiency. Moreover, it lowers the overpotential and effectively catalyzes the charge and discharge processes to attain the high specific capacity and high-rate cycling performance of lithium-rich oxygen batteries. Single atoms, despite their potential, are inherently unstable due to their high surface energy, which drives them to aggregate during synthesis and catalytic reactions. This aggregation poses a significant challenge in the creation of isolated single-atom catalysts with long-term stability. In this work, we present a novel, gentle synthesis approach to fabricate a stable iridium single-atom electrocatalyst (Ir/N-PAQR SAC). To keep the structural stability and catalytic activity of a single-atom catalyst, the SAC approach is preferred over high-energy ball milling for the synthesis of cathode material (Li₂O/Ir/N-PAQR SAC). A low-metal-loading (2.73%) iridium single-atom electrocatalyst effectively catalyzed the conversion reaction in the cathode during charging and discharging, lowered the charge polarization, and achieved a high discharge capacity of 455 mA h g^–1, at 0.1C, and a high rate capacity of 434 mA h g^–1 at 1C. It also exhibits an outstanding cycling performance at 1C with a capacity retention of 86.8% after 100 cycles. Furthermore, the Li₂O/Ir/N-PAQR SAC cathode shows fast charging with the capacity of 120 mA h g^–1 and 41 mA h g^–1 at low temperatures (−10 °C and −20 °C, respectively). Finally, it is concluded that compared to high-metal-loading electrocatalysts, the iridium single-atom electrocatalyst (Li₂O/Ir/N-PAQR SAC) with low metal loading shows excellent electrochemical performance.