With a long cycle life, high rate capability, and facile cell fabrication, liquid metal batteries are regarded as a promising energy storage technology to achieve better utilization of intermittent renewable energy sources. Nevertheless, conventional liquid metal batteries need to be operated at relatively high temperatures (>240 °C) to maintain molten-state electrodes and high conductivity of electrolytes. Intermediate and room-temperature liquid metal batteries, circumventing complex thermal management as well as issues related to sealing and corrosion, are emerging as a novel energy system for widespread implementation. In this Outlook, we elaborate the appealing features of fusible alloys-based liquid metals for energy storage devices and describe the metallurgical fundamentals, cost, and safety analysis of fusible alloys. Recent advances are discussed covering the rational screening of metallic alloys, interfacial engineering on the electrodes, and design of advanced electrolytes. In the end, we provide perspectives on current challenges and future opportunities in this field. This outlook not only aims to provide a design principle for high performance liquid metal batteries, but also inspires further development of novel energy systems beyond conventional solid-state batteries and high-temperature batteries.
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