Soft materials tend to be highly permeable to gases, making it difficult to create stretchable hermetic seals. With the integration of spacers, we demonstrate the use of liquid metals, which show both metallic and fluidic properties, as stretchable hermetic seals. Such soft seals are used in both a stretchable battery and a stretchable heat transfer system that involve volatile fluids, including water and organic fluids. The capacity retention of the battery was ~72.5% after 500 cycles, and the sealed heat transfer system showed an increased thermal conductivity of approximately 309 watts per meter-kelvin while strained and heated. Furthermore, with the incorporation of a signal transmission window, we demonstrated wireless communication through such seals. This work provides a route to create stretchable yet hermetic packaging design solutions for soft devices.

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Electrocatalysts play a critical role in electrochemical catalytic processes. In order to rationally design active and durable electrocatalysts, it is crucial to have a deep understanding on the formation mechanism of the electrocatalysts. With the development of in situ transmission electron microscopy (TEM) techniques, it is possible to observe nanoscale behaviors in real‐time to probe the formation of various electrocatalysts. Here, the nucleation, growth, attachment, diffusion, corrosion and other nanoscale dynamics related to the formation of zero‐dimensional (0D), one‐dimensional (1D), and two‐dimensional (2D) nanomaterials are discussed. The current challenges and potential opportunities for in situ techniques towards observation of electrocatalyst formation including high resolution, fast imaging and beam effect are also described.

This paper reports the generation of 3D thermal and electrical conductive graphene network in gallium‐based liquid metal (LM) via a simple one‐step ball‐milling approach. In this work, 2D graphene nanoplates and their derivatives were employed to construct 3D thermal and electrical conductive filler networks. It is demonstrated that the obtained composite exhibits the highest 3D thermal conductivity (44.6 W m−1 K−1) among the other gallium‐based LM composites with 2D inorganic nanofillers and distinguished electrical conductivity (8.3 S µm−1) among gallium‐based LM composites at present. The enhanced thermal conductivity and wettability of gallium‐based composite lead to its beneficial usage as thermal interface materials with exquisite texture for LED chip heat dissipation. The electrochemical and magnetic experiments confirm that these LM‐based composites can also be controlled under external electrical or magnetic field, which potentially can help extend their application in external field‐driven systems. The findings of this work offer new insight in designing LM‐based composites with enhanced thermal, electrical, and magnetic properties for a wide range of applications, including thermal management systems, 3D printing, flexible conductors, soft robotic systems, and wearable energy technologies.

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