An Inorganic Electrolyte Li–O₂ Battery with High Rate and Improved Performance

As an alternative to air intolerant nonaqueous electrolytes, a LiNO3–KNO2–CsNO3 (37:39:24) eutectic salt mixture at 140 °C is investigated as a molten electrolyte for Li–O2 batteries. The inorganic eutectic promotes the highly reversible formation–decomposition mechanism of Li2O2, as a robust electrolyte in oxidative conditions. An in situ formed shielding layer composed of Li2O and Li3N keeps the Li anode intact during vigorous cell conditions, providing faster Li-ion diffusion kinetics and stable cycling performance. We report an inorganic electrolyte Li–O2 battery that exhibits the lowest charge–discharge overpotentials of 40 mV and high rate capabilities at 3 mA/cm2 and is cycleable up to 200 times at a restricted capacity of 500 mAh/gcarbon. The performance is achieved on a bare carbon electrode with a round-trip energy efficiency close to 98%. This work emphasizes that the use of an inorganic electrolyte would significantly eliminate the side reactions associated with charge–discharge reactions and boosts the promise of realizing next generation batteries.