A high-energy-density and long-life lithium-ion battery via reversible oxide–peroxide conversion

Li–O 2 batteries have received considerable attention owing to their high theoretical gravimetric energy densities. However, the sluggish kinetic barrier between gaseous O 2 and solid products leads to severe polarized overpotenial. Besides, the gas-open cell architecture and cumbrous O 2 storage accessories bring additional burdens on practical application. Here, by pre-embedding Li 2 O nanoparticles into an iridium–graphene catalytic host, we confine the O 2 -free reversible Li 2 O/Li 2 O 2 interconversion within a sealed cell environment. After rationally controlling the depth of charge, the O 2 /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.