Liquid Metal Powders Wrapped with Robust Shell by Bimetallic Ions Chelation Strategy for Energy Harvesting and Flexible Electronics

Abstract

Excellent electrical and fluidic properties render liquid metal (LM) a promising material for flexible electronics, soft robotics, and stretchable circuits. Although producing LM micro/nano droplets by nanometerization addresses the tricky issue of the processing result from high surface tension, it still remains challenging to obtain stable LM droplets because of their dynamic surfaces. In this study, LM powders wrapped with robust shells are fabricated by bimetallic ions chelation strategy. During sonicating LM (e.g., EGaIn) in an alginate solution, a microgel shell is first formed by the coordination of Ga3+ and carboxyl groups. Subsequently, LM powders are achieved by introducing Ca2+ as secondary metal ions to chelate with redundant carboxyl groups. Besides high chemical stability in water and air, these nonstick LM powders also exhibit superior photothermal effects for energy harvesting, being capable of recovering electrical conductivity by mechanical sintering for flexible electronics. These conductive circuits based on LM powders not only work as electro-thermal heaters, and electromagnetic interference shielding material but also can be designed as smart actuators. Thus, this bimetallic ions chelation strategy may start a pathway to produce stable, transportable LM powders with multifunctional properties, applicable in stretchable electronics, smart actuators, and electric skins.