Defect‐Morphology Dual Strategy to Achieve Coral‐Like La _1‐ <i> _x </i> Ni _0.5‐y Fe _0.5 O _3‐δ /NiO Bifunctional Catalysts for High‐Performance Li‐O ₂ Batteries

Perovskite oxides have emerged as promising cathode catalyst candidates for Li-O₂ batteries due to their structural tunability, bifunctional catalytic activity, high chemical/structural stability, and high cost-effectiveness. However, the key challenges, inferior intrinsic conductivity and limited exposure of accessible active sites, have been hindering their practical application. Herein, a dual strategy of La-site deficiency and morphological regulation was proposed to in situ synthesize the coral-like La_1- _xNi_0.5-yFe_0.5O_3-δ/NiO composites as high-performance bifunctional catalysts for Li-O₂ batteries for the first time. La-site deficiency not only induces the in situ formation of the NiO functional phase but also modulates the electronic structures (oxygen vacancy concentration and transition metal oxidation states). Additionally, the addition of ethylenediaminetetraacetic acid (EDTA) chelating agent creates a coral-like structure, which effectively facilitates the mass transfer process and provides increased storage space for Li₂O₂. The Li-O₂ battery with La_0.7 ^EDTA catalyst exhibits exceptional electrochemical performance: low charge-transfer resistance (42 Ω), high discharge capacity (2.84 mAh), and extended cycling stability (121 cycles at 100 mA g^-1-0.5 mAh). More importantly, rate capability measurements unveil that the morphological regulation plays a more critical role at current densities below 200 mA g^-1, whereas the contribution of La-site deficiency becomes predominant at higher current densities. This work establishes a materials design paradigm coupling atomic-scale defects with bio-inspired 3D architectures for advanced energy storage systems.