Stretchable Energy Storage with Eutectic Gallium Indium Alloy

A highly stretchable liquid metal-based electrode is developed via a one-step process, retaining conductivity and capacitance after mechanical deformation up to 900% strain. The stretchable all-solid-state device provides a areal energy density of 43 µWh cm⁻² after 150% strain. In situ Raman spectroscopy and DFT calculations reveal unique gallium-bis(trifluoromethane)sulfonimide (Ga-TFSI) interactions, making it promising for stretchable energy storage.

Abstract

The integration of electronics with the human body or wearables necessitates the evolution of energy storage devices capable of seamless adaptation to the conformability of the skin and textiles. This work focuses on developing an intrinsically stretchable electrode prepared by sedimenting the liquid metal particles in a conductive stretchable matrix. The liquid metal-based electrode can be stretched to ≈900% strain, and its conductivity increases by extending to 250% and retaining its initial conductivity at 500% strain. Benefitting from these properties, the assembled all-solid-state energy storage device provides high stretchability of up to 150% strain and a capacity of 0.42 mAh cm⁻³ at a high coulombic efficiency of 90%. The charge storage mechanism is investigated by probing the electrode/electrolyte interface, uncovering the intricate gallium-bis(trifluoromethane)sulfonimide (Ga-TFSI) complexation during electrochemical cycling through in situ Raman spectroscopy, ex situ X-ray photoelectron spectroscopy (XPS) analyses, and density functional theory (DFT) calculations. This work offers a promising avenue for the advancement of stretchable batteries.