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For electronics to be wearable, contactless charging and overall deformability are necessary pre-conditions. However, the current heterogeneous integration based on different active materials and separate manufacturing often leads to mechanical mismatch. Here, we report an ultrastretchable all-in-one integrated MXene-based microsystem comprising wireless coils, micro-supercapacitors (MSCs) and strain sensors. The seamless configuration without any connecting interface dramatically improves the structural integrity of the microsystem, and a pre-crumpled structure endows it with superior stretchability. Attributed to these, our MSCs can be wirelessly charged in ~20 s under various types of deformation and are capable of powering strain sensors, responding rapidly to body motion signals. Moreover, the MSCs display a high specific capacitance of 76.82 F cm–3, and superb mechanical stability with 98.5% capacitance retention after biaxial stretching 1000 cycles from 0% to 500% areal strain. Therefore, this work sheds new insights into design and implementation of skin-attachable wireless microelectronics. The authors report a stretchable and integrated energy harvest-storage-application skin-adherent microsystem, by utilizing an all-in-one MXene film simultaneously as micro-supercapacitors, wireless receiver coils and strain sensors. [ABSTRACT FROM AUTHOR]

2D materials have garnered considerable interest in various applications from catalysis to energy storage. However, the self‐stacking and poor air stability of 2D materials (e.g., MXene) leads to serious performance degradation, in particular, of micro‐supercapacitors (MSCs) with narrow working voltage and low energy density. Here, a universal confined interfacial assembly strategy is demonstrated for controllably synthesizing a series of 2D mesoporous heterostructures for high‐voltage and high‐energy ionogel‐based MSCs. This assembly process reveals accurate controllability and extraordinary versatility, endowing the 2D mesoporous heterostructures with highly adjustable mesopore size (7–22 nm), tunable thickness (15–29 nm), variable carbon precursors (including oligochitosan, glucose, and sucrose), and replaceable 2D substrates (e.g., MXene, graphene, BN, and MoS2). As a proof of concept, the 2D mesoporous carbon@MXene based MSCs with ionic liquid ionogel electrolyte deliver ultrahigh voltage of 3.7 V, superior areal energy density of 181.3 µWh cm−2, excellent flexibility with 99% of capacitance retention at 180°, and excellent modular self‐integration for variable voltage/capacitance output, surpassing most reported MXene based MSCs. Therefore, this work will open a novel available paradigm for scalable fabrication of 2D mesoporous materials to target high‐performance and functional microscale power source. [ABSTRACT FROM AUTHOR]

High‐concentration electrolyte effectively improves the energy density and anti‐freezing property of aqueous micro‐supercapacitors (MSCs), endowing them the opportunity serving as power sources for miniaturized electronics. However, the excessive usage of salt significantly increases the cost of the electrolyte. Herein, a cost‐effective moderate‐concentration hybrid electrolyte is designed by introducing CaCl2 and ethylene glycerol (EG) additives for low‐temperature and high‐voltage MSCs. The results manifest that the introduction of CaCl2 minimizes the number of water molecules with strong hydrogen bonds while the addition of EG can reduce the amount of H2O molecules in the primary solvation shell sheath of Ca2+ ion and strengthen the hydrogen bonds between EG and water molecules, thus endowing the optimal electrolyte with a wide electrochemical stability window of 3.5 V and a freezing point lower than −120 °C. Furthermore, the resulting hybrid MSCs offer a high voltage of 1.6 V, and realize 62% capacitance retention at −40 °C compared to that at room temperature. Moreover, The MSCs can endure 20000 cycles with 98.5% capacitance retention at −40 °C. This work provides a meaningful guidance for designing low‐cost moderate‐concentration hybrid electrolyte with wide electrochemical stability window and anti‐freezing property for intrinsically safe and environmentally adaptable devices. [ABSTRACT FROM AUTHOR]