Li–O₂ batteries have received considerable attention owing to their high theoretical gravimetric energy densities. However, the sluggish kinetic barrier between gaseous O₂ and solid products leads to severe polarized overpotenial. Besides, the gas-open cell architecture and cumbrous O₂ storage accessories bring additional burdens on practical application. Here, by pre-embedding Li₂O nanoparticles into an iridium–graphene catalytic host, we confine the O₂-free reversible Li₂O/Li₂O₂ interconversion within a sealed cell environment. After rationally controlling the depth of charge, the O₂/superoxo-free charge capacity can be extended to 400 mAh g^–1 (based on the entire cathodic loading mass), with only 0.12 V round-trip overpotential. Ultrastable rechargeability can be achieved for over 2,000 cycles with 99.5% coulombic efficiency. Moreover, matched with a silicon anode, the full-cell output gravimetric energy density can reach nearly 600 Wh kg^–1 (based on the loading mass of both electrodes). This work shows that reversible oxide–peroxide conversion can be utilized for the development of high-energy-density sealed battery technologies.

Li-O ₂电池由于其较高的理论重量能量密度而备受关注。但是，气态O ₂和固体产物之间的动力学迟滞导致严重的极化过电位。此外，气体开放式电池结构和繁琐的O ₂储存附件给实际应用带来了额外的负担。在这里，通过将Li ₂ O纳米粒子预先嵌入到铱-石墨烯催化主体中，我们将无O _2的可逆Li ₂ O / Li ₂ O ₂相互转换限制在密封的电池环境中。合理控制电荷深度后，O ₂/ superoxo-free的充电容量可以扩展到400 mAh g ^–1（基于整个阴极负载质量），仅具有0.12 V的双向往返电势。超过2,000个循环可实现超稳定的充电能力，库仑效率为99.5％。此外，与硅阳极配合使用，全电池输出重量能密度可以达到近600 Wh kg ^–1（基于两个电极的负载质量）。这项工作表明，可逆的氧化物-过氧化物转化可用于开发高能量密度密封电池技术。