Li-O₂ battery is one of the most attractive energy storage technologies because of its extremely high energy density (3500 Wh kg⁻¹). However, the main limitation of the battery is the high energy barrier during the formation and decomposition of the discharge product (Li₂O₂), which results in a series of problems such as large overpotential and poor cycle stability. Herein, the Fe-doped spinel Ni-Co oxides are employed as the cathode catalyst to decrease the energy barrier of the oxygen electrode reactions in Li-O₂ battery. The batteries with Fe-doped Ni-Co oxides deliver a large discharge specific capacity of 16,727 mAh g⁻¹ and remarkable durability of over 790 h at current density of 500 mA g⁻¹. Based on the density functional theory (DFT) calculation, the optimized performance is attributed to the near-unity e_g electron occupancy (1.32) in transition metal atom for iron-doped Ni-Co oxide as compared to that for undoped Ni-Co oxide (1.64). The near-unity e_g electron occupancy can increase the covalency of transition metal-oxygen bonds and finally enhance the electrocatalytic activity. This study is helpful for deeply understanding the relationship between the surface electronic structure and catalytic activity of oxygen electrocatalysts in Li-O₂ cells.

Li-O ₂电池因其极高的能量密度（3500 Wh kg ^-1）而成为最具吸引力的储能技术之一。然而，电池的主要局限在于放电产物（Li ₂ O ₂）形成和分解过程中的高能垒，导致过电位大、循环稳定性差等一系列问题。在此，Fe掺杂的尖晶石Ni-Co氧化物用作阴极催化剂以降低Li-O ₂电池中氧电极反应的能量势垒。具有 Fe 掺杂的 Ni-Co 氧化物的电池提供了 16,727 mAh g ^-1的大放电比容量并且在 500 mA g ^{-1 的}电流密度下具有超过 790 小时的卓越耐久性。基于密度泛函理论（DFT）计算，优化的性能归因于近统一Ê_克电子占有相比，对于未掺杂的镍钴氧化物为掺杂铁的镍-钴氧化物（1.32）中的过渡金属原子(1.64)。近统一Ê_克电子占有可以增加过渡金属-氧键的共价性和最终提高的电催化活性。该研究有助于深入了解Li-O ₂电池中氧电催化剂的表面电子结构与催化活性之间的关系。