Anionic redox reactions in cathodes of lithium-ion batteries are allowing opportunities to double or even triple the energy density. However, it is still challenging to develop a cathode, especially with Earth-abundant elements, that enables anionic redox activity for real-world applications, primarily due to limited strategies to intercept the oxygenates from further irreversible oxidation to O₂ gas. Here we report simultaneous iron and oxygen redox activity in a Li-rich anti-fluorite Li₅FeO₄ electrode. During the removal of the first two Li ions, the oxidation potential of O²⁻ is lowered to approximately 3.5 V versus Li⁺/Li⁰, at which potential the cationic oxidation occurs concurrently. These anionic and cationic redox reactions show high reversibility without any obvious O₂ gas release. Moreover, this study provides an insightful guide to designing high-capacity cathodes with reversible oxygen redox activity by simply introducing oxygen ions that are exclusively coordinated by Li⁺.

锂离子电池阴极中的阴离子氧化还原反应使能量密度增加一倍甚至三倍。然而，开发阴极，尤其是利用富含地球的元素的阴极，仍然具有挑战性，该阴极能够在实际应用中实现阴离子氧化还原活性，这主要是由于有限的策略来拦截含​​氧化合物进一步不可逆地氧化为O ₂气体。在这里，我们报告同时在富含锂的抗萤石Li ₅ FeO ₄电极中铁和氧的氧化还原活性。在除去前两个Li离子期间，O ²⁻的氧化电位相对于Li ⁺ / Li ⁰降低到大约3.5 V，在该电位下同时发生阳离子氧化。这些阴离子和阳离子氧化还原反应显示出高可逆性，而没有任何明显的O ₂气体释放。此外，本研究为通过引入仅由Li ⁺配位的氧离子提供了具有指导意义的指导，以设计具有可逆氧氧化还原活性的高容量阴极。