Molten salts are a unique type of electrolyte enabling high-temperature electrochemical energy storage (EES) with unmatched reversible electrode kinetics and high ion-conductivities, and hence impressive storage capacity and power capability. However, their high tendency to evaporate and flow at high temperatures challenges the design and fabrication of the respective EES devices in terms of manufacturing cost and cycling durability. On the other hand, most of these EES devices require lithium-containing molten salts as the electrolyte to enhance performances, which not only increases the cost but also demands a share of the already limited lithium resources. Here we report a novel quasi-solid-state (QSS) electrolyte, consisting of the molten eutectic mixture of Na₂CO₃-K₂CO₃ and nanoparticles of yttrium stabilized zirconia (YSZ) in a mass ratio of 1:1. The QSS electrolyte has relatively lower volatility in comparison with the pristine molten Na₂CO₃-K₂CO₃ eutectic, and therefore significantly suppresses the evaporation of molten salts, thanks to a strong interaction at the interface between molten salt and YSZ nanoparticles at high temperatures. The QSS electrolyte was used to construct an iron-air battery that performed excellently in charge-discharge cycling with high columbic and energy efficiencies. We also propose and confirm a redox mechanism at the three-phase interlines in the negative electrode. These findings can help establish a simpler and more efficient approach to designing low-cost and high-performance molten salt metal-air batteries with high stability and safety.

熔融盐是一种独特的电解质，可实现高温电化学能量存储（EES），具有无与伦比的可逆电极动力学和高离子电导率，因此具有出色的存储容量和功率容量。然而，它们在高温下蒸发和流动的高度趋势在制造成本和循环耐久性方面挑战了各个EES设备的设计和制造。另一方面，这些EES设备中的大多数需要含锂的熔融盐作为电解质来增强性能，这不仅增加了成本，而且还需要一部分已经有限的锂资源。在这里，我们报告一种新型的准固态（QSS）电解质，该电解质由Na ₂ CO ₃ -K ₂的熔融低共熔混合物组成CO ₃和钇稳定的氧化锆（YSZ）纳米粒子的质量比为1：1。与原始熔融的Na ₂ CO ₃ -K ₂ CO ₃相比，QSS电解质具有相对较低的挥发性。由于在高温下熔融盐和YSZ纳米颗粒之间的界面处有很强的相互作用，因此共晶，因此显着抑制了熔融盐的蒸发。QSS电解质用于构造铁-空气电池，该电池在充放电循环中表现出色，具有高的哥伦比亚和能量效率。我们还提出并确认了负极中三相交线处的氧化还原机理。这些发现可以帮助建立一种更简单，更有效的方法来设计具有高稳定性和安全性的低成本高性能的熔融盐金属空气电池。