Batteries are an attractive grid energy storage technology, but a reliable battery system with the functionalities required for a grid such as high power capability, high safety and low cost remains elusive. Here, we report a solid electrolyte-based molten lithium battery constructed with a molten lithium anode, a molten Sn–Pb or Bi–Pb alloy cathode and a garnet-type Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) solid electrolyte tube. We show that the assembled Li||LLZTO||Sn–Pb and Li||LLZTO||Bi–Pb cells can stably cycle at an intermediate temperature of 240 °C for about one month at current densities of 50 mA cm⁻² and 100 mA cm⁻² respectively, with almost no capacity decay and an average Coulombic efficiency of 99.98%. Furthermore, the cells demonstrate high power capability with current densities up to 300 mA cm⁻² (90 mW cm⁻²) for Li||LLZTO||Sn–Pb and 500 mA cm⁻² (175 mW cm⁻²) for Li||LLZTO||Bi–Pb. Our design offers prospects for grid energy storage with intermediate temperature operations, high safety margin and low capital and maintenance costs.

电池是一种有吸引力的电网储能技术，但是具有电网所需功能（例如高功率能力，高安全性和低成本）的可靠电池系统仍然遥不可及。在这里，我们报告了一种基于固体电解质的熔融锂电池，该电池由熔融锂阳极，熔融Sn-Pb或Bi-Pb合金阴极和石榴石型Li _6.4 La ₃ Zr _1.4 Ta _0.6 O ₁₂（LLZTO）固体电解质构成管子。我们表明，组装锂|| || LLZTO的Sn-Pb和Li || || LLZTO铋-铅细胞可以稳定地循环，在240℃在50mA厘米的电流密度的中间温度为约一个月^-2和100 mA厘米^-2几乎没有容量衰减，平均库仑效率为99.98％。此外，电池显示出高功率能力，对于Li || LLZTO || Sn-Pb ，电流密度高达300 mA cm ^-2（90 mW cm ^-2），对于Li ，电流密度高达500 mA cm ^-2（175 mW cm ^-2） || LLZTO || Bi-Pb。我们的设计提供了具有中等温度操作，高安全裕度以及低资本和维护成本的电网储能前景。