Benchmarking La‐Based Perovskites as Bifunctional Cathodes For Primary and Rechargeable Zinc−Air Batteries with Biopolymer‐Based Electrolyte

Abstract

AbstractState‐of‐the‐art perovskite‐based electrocatalysts for zinc−air batteries (ZABs) may include one or more Critical Raw Materials (CRMs) like Co, Ru, and rare earth elements, for oxygen reduction/evolution reactions. Under the warnings described by the CRMs Act in Europe, future research in this field must limit the use of these elements, find more sustainable formulations, and better design/integration strategies to trade off costs, supply, and performances. In this benchmarking study, three main perovskites, i. e., LaNiO3‐δ (LNO), LaMnO3+δ (LMO), and LaMn0.5Ni0.5O3 (LMNO), are studied as quasi‐CRM‐free benchmarks and integrated with a novel gel electrolyte from a natural biopolymer in primary and secondary ZABs. By comparing literature performances based on the number of total/active site CRMs for the first time, these reference perovskites showed Zn utilizations >90 % in primary ZABs, with LMO and LMNO approaching 94 % at 2 mA/cm2, the highest result in the field. In secondary ZABs, LMO demonstrated limited cyclability (62 cycles), while LMNO had a moderate number of cycles (117 cycles) and the highest round‐trip efficiency (54.3 %), while LNO presented the lowest charge potential (2.04 V) and longer cyclability (455 cycles). This work demonstrates encouraging performance with fewer CRMs and proper integration in more sustainable ZABs, opening the way to future CRM‐free perovskites.