Design Principles and Applications of Next‐Generation High‐Energy‐Density Batteries Based on Liquid Metals

Increasing need for the renewable energy supply accelerated the thriving studies of Li‐ion batteries, whereas if the high‐energy‐density Li as well as alkali metals should be adopted as battery electrodes is still under fierce debate for safety concerns. Recently, a group of low‐melting temperature metals and alloys that are in liquid phase at or near room‐temperature are being reported for battery applications, by which the battery energy could be improved without significant dendrite issue. Besides the dendrite‐free feature, liquid metals can also promise various high‐energy‐density battery designs on the basis of unique materials properties. In this review, the design principles for liquid metals‐based batteries from mechanical, electrochemical, and thermodynamical aspects are provided. With the understanding of the theoretical basis, currently reported relevant designs are summarized and analyzed focusing on the working mechanism, effectiveness evaluation, and novel application. An overview of the state‐of‐the‐art liquid metal battery developments and future prospects is also provided in the end as a reference for further research explorations. A comprehensive overview of applications on low‐melting‐temperature liquid metals in next‐generation high‐energy‐density batteries is presented. Starting from the theoretical basis of materials properties and electrochemical features with liquid metals and alloys, reported applications are summarized by working mechanisms, critically evaluated with strengths and issues, and proposed with future development directions in the field.