Heme-Based Nanozymes as Redox Mediators and Oxygen Shuttles for Li–O₂ Batteries with High Cycle Performance

Organic electrolyte Li–O2 batteries with high theoretical energy density are regarded as the most promising new form of energy batteries, and the primary issues of these batteries include superoxide-related parasitic processes and large overpotentials during charging. In this research, a heme-based nanozyme containing an iron porphyrin derivative ligand was employed as an electrolyte for Li–O2 batteries by putting it into tetraethylene glycol dimethyl ether (TEGDME). This type of nanozyme can play a bifunctional role in the electrolyte: (1) the heme-based nanozyme can scavenge superoxide radicals from the electrolyte, and (2) the heme-based nanozyme can facilitate redox reactions by acting as molecular shuttles of superoxide species and electrons between the cathode and the products by combining with superoxide intermediates in the electrolyte. It was revealed that in the presence of nanozymes, the discharge capacity of Li–O2 batteries was enhanced by 67%, electrode polarization was improved, and the number of battery cycles was doubled. In addition, the nanozymes assisted the decomposition of Li2O2 during the charging process. This study focuses on the rational design of solution-based multifunctional electrolyte additives and provides a sustainable cross-link between biomolecules and improved energy storage.