Boosting the Li-O2 pouch cell beyond 860 Wh kg−1 by an O2-enriched localized high-concentration electrolyte

Abstract Lithium-oxygen batteries (LOBs) are considered to be the next generation of high specific energy storage devices. To improve the practical specific energy, LOBs typically require thick cathode electrodes to achieve higher areal capacity. However, due to the inefficient O2 diffusion within the electrolyte-flooded thick cathodes, the practical discharge capacity of LOBs is significantly lower than their ultra-high theoretical value. Herein, we propose a strategy to solve the problem of limited O2 diffusion in thick cathodes of LOBs by applying an O2-enriched localized high-concentration electrolyte (LHCE). With a thick cathode (10 mg cm−2), LOBs based on this O2-enriched LHCE deliver impressive discharge capacities of 50.4 mAh cm−2, 27.1 mAh cm−2 and 20.3 mAh cm−2 at current densities of 0.1 mA cm−2, 0.3 mA cm−2 and 0.5 mA cm−2, respectively. The discharge product Li2O2 is homogeneously distributed within the thick cathode due to the enhanced O2 diffusion conferred by the O2-enriched LHCE, indicating that the products storage space of the thick cathode is more efficiently utilized. Besides, the O2-enriched LHCE-based LOBs derive a stable SEI to protect the Li anode from O2 corrosion. Additionally, a pioneering primary Li-O2 pouch cell with the O2-enriched LHCE achieves an exceptional specific energy of 860.6 Wh kg−1 (based on the total pouch cell weight), providing a promising technical pathway for the practical application of LOBs.