The development of a cathode for solid-state lithium-oxygen batteries has been hindered in practice by a low capacity and limited cycle life despite their potential for high energy density. Here, a previously unexplored strategy is proposed wherein the cathode delivers a specific capacity of 200 milliampere hour per gram over 665 discharge/charge cycles, while existing cathodes achieve only ~50 milliampere hour per gram and ~100 cycles. A highly conductive mixed ionic-electronic conductors (MIECs) are designed as a carbon-free cathode by first-principles calculations with a density functional theory (DFT) and nudged elastic band (NEB) to avoid the degradation associated with carbonaceous materials, implying an improvement in stability during the electrochemical cycling [1]. In addition, water vapor is added into the main oxygen gas as an additive to change the discharge product from growth-restricted lithium peroxide to easily grown lithium hydroxide, resulting in a significant increase in capacity [2]. Thus, the proposed strategy is effective for developing reversible solid-state lithium-oxygen batteries with high energy density. We will discuss on the systematic materials design and their electrochemical properties for solid-state lithium-oxygen batteries at the meeting.

References

[1] Sang Bok Ma et al., Advanced Energy Materials, 10 (2020) 2001767.

[2] Mokwon Kim et al., Science Advances, in press.