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Self‐healing secondary batteries have attracted great attention for constructing stable energy‐storage systems. Herein, a novel self‐healing rechargeable magnesium battery cathode is developed using self‐healing microcapsules in a vanadium pentoxide microflower‐based cathode. The microcapsules are prepared through a microfluidic approach. The core of the microcapsule contains a conductive hydrogel and carbon nanospheres, and the shell composes of a UV‐curved polymer. When the self‐healing Mg battery cathode cracks, the microcapsules break and release the core into the cracks, rebuilding the pathways for the electron transport and enabling a stable electrochemical performance. The presented cathode displays a good capacity of 105 mAh g−1 after 500 cycles at 100 mA g−1 and it delivers a stable capacity of 98.3 mAh g−1 after long‐term cycling 1000 times at 200 mA g−1. A recoverable rate‐performance and a good temperature tolerance are also achieved. It is expected that the general preparation approach of the self‐healing microcapsules and the long‐term stable Mg battery will find broad applications for developing many emerging energy‐storage systems. [ABSTRACT FROM AUTHOR]

Magnesium batteries have been considered promising candidates for next‐generation energy storage systems owing to their high energy density, good safety without dendrite formation, and low cost of magnesium resources. However, high‐performance cathodes with stable capacity, good conductivity, and fast ions transport are needed, since many conventional cathodes possess a low performance and poor preparation controllability. Herein, a liquid‐driven coaxial flow focusing (LDCFF) approach for preparing a novel microcapsule system with controllable size, high loading, and stable magnesium‐storage performance is presented. Taking the MoS2‐infilled microcapsule as a case study, the magnesium battery cathode based on the microcapsules displays a capacity of 100 mAh g−1 after 100 cycles. High capacity retention is achieved at both low and high temperatures of −10, ‒5, and 45 °C, and a stable rate‐performance is also obtained. The influences of the liquid flow rates on the size and shell thickness of the microcapsules are investigated; and electron and ion diffusion properties are also studied by first‐principle calculations. The presented LDCFF method is quite general, and the high performance of the microcapsules enables them to find broad applications for making emerging energy‐storage materials and secondary battery systems. [ABSTRACT FROM AUTHOR]

Microencapsulated materials are receiving broad attention for applications as diverse as energy storage and conversion, biomedicine, self‐healing materials, and electronics. Here, a general microfluidic approach is presented to prepare phase‐change material‐infilled microcapsules with unique thermal and mechanical properties. Aqueous sodium acetate solutions are encapsulated by an acrylate‐based shell via a microfluidic method. To understand and optimize microcapsule formation, flow behavior during the encapsulation is numerically simulated. When the microcapsules are embedded in an acrylate matrix (same composition as the shell wall material), the microcapsules exhibit a significant 46.6 ºC difference between the crystallization and melting temperatures as determined by differential scanning calorimetry at a rate of 10 ºC per min. Variable temperature dynamic mechanical analysis over the range of 50 to ‐90 ºC reveals up to a 50% change in the composite's elastic modulus at a given temperature, depending on if the sample is being cooled or heated, due to significant undercooling of the core material crystallization as shown by X‐ray diffraction. [ABSTRACT FROM AUTHOR]

Large volume expansion and structural breaking have been severe issues for emerging high‐performance secondary battery anodes. Herein, a novel microcapsule anode filled with tin (Sn) nanoflowers is presented, which is prepared through in situ interface polymerization of an oil‐in‐water emulsion system. The carbon shell of the microcapsules reduces the pulverization of the encapsulated Sn, and the voids inside the capsules provide efficient spaces for the volume change of Sn during lithiation–delithiation. The Sn‐filled microcapsules exhibit a high rate performance with a capacity decay rate as low as 0.38%, even after three rounds of repeated tests, and a stable capacity of 800 mAh g−1 after 200 cycles at 380 mA g−1. In addition, the electron transfer kinetics and Li‐ion diffusion are investigated, which indicate that the microcapsule system enables a good environment for both electron and ion transfer. [ABSTRACT FROM AUTHOR]