Recently developed flexible mechanosensors based on inorganic silicon, organic semiconductors, carbon nanotubes, graphene platelets, pressure-sensitive rubber and self-powered devices are highly sensitive and can be applied to human skin. However, the development of a multifunctional sensor satisfying the requirements of ultrahigh mechanosensitivity, flexibility and durability remains a challenge. In nature, spiders sense extremely small variations in mechanical stress using crack-shaped slit organs near their leg joints. Here we demonstrate that sensors based on nanoscale crack junctions and inspired by the geometry of a spider's slit organ can attain ultrahigh sensitivity and serve multiple purposes. The sensors are sensitive to strain (with a gauge factor of over 2,000 in the 0-2 per cent strain range) and vibration (with the ability to detect amplitudes of approximately 10 nanometres). The device is reversible, reproducible, durable and mechanically flexible, and can thus be easily mounted on human skin as an electronic multipixel array. The ultrahigh mechanosensitivity is attributed to the disconnection-reconnection process undergone by the zip-like nanoscale crack junctions under strain or vibration. The proposed theoretical model is consistent with experimental data that we report here. We also demonstrate that sensors based on nanoscale crack junctions are applicable to highly selective speech pattern recognition and the detection of physiological signals. The nanoscale crack junction-based sensory system could be useful in diverse applications requiring ultrahigh displacement sensitivity.

A multiscale architectured solid oxide fuel cell is demonstrated by applying a large-area ceramic micropatterning and thin-film deposition processes.

Sulfide solid electrolytes (SEs) with high Li-ion conductivities (σ ion ) and soft mechanical properties have limited applications in wet casting processes for commercial all-solid-state batteries (ASSBs) because of their inherent atmospheric and chemical instabilities. In this study, we fabricated sulfide SEs with a novel core–shell structure via environmental mechanical alloying, while providing sufficient control of the partial pressure of oxygen. This powder possesses notable atmospheric stability and chemical resistance because it is covered with a stable oxysulfide nanolayer that prevents deterioration of the bulk region. The core–shell SEs showed a σ ion of more than 2.50 mS cm –1 after air exposure (for 30 min) and reaction with slurry chemicals (mixing and drying for 31 min), which was approximately 82.8% of the initial σ ion . The ASSB cell fabricated through wet casting provided an initial discharge capacity of 125.6 mAh g –1 . The core–shell SEs thus exhibited improved powder stability and reliability in the presence of chemicals used in various wet casting processes for commercial ASSBs.

The performance of solid oxide fuel cells can be improved by introducing micro-patterns on their electrolyte layer.

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Micropatterning is considered a promising strategy for improving the performance of electrochemical devices. However, micropatterning on ceramic is limited by its mechanically fragile properties. This paper reports a novel imprinting-assisted transfer technique to fabricate an interlayer structure in a protonic ceramic electrochemical cell with a micropatterned electrolyte. A dense proton-conducting electrolyte, BaCe0.7Zr0.1Y0.1Yb0.1O3−δ, is micropatterned in a chevron shape with the highest aspect ratio of patterns in electrode-supported cells to the best of our knowledge, increasing surface areas of both electrode sides more than 40%. The distribution of relaxation time analysis reveals that the chevron-patterned electrolyte layer significantly increases the electrode contact areas and active electrochemical reaction sites at the vicinity of the interfaces, contributing to enhanced performances of both the fuel cell and electrolysis operations. The patterned cell demonstrates improved fuel cell performance (>45%) and enhances electrolysis cell performance (30%) at 500 °C. This novel micropatterning technique is promising for the facile production of layered electrochemical cells, further opening a new route for the performance enhancement of ceramic-based electrochemical cells.

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The atmospheric hydrolysis reaction in sulfide solid electrolytes (SEs) is destructive to their Li-ion conducting behavior, but a comprehensive understanding of their reaction steps is still lacking. Therefore, here, we studied the atmospheric deterioration of a well-known sulfide SE, Li 7 P 3 S 11 , based on the analogies between the hydrolysis and electrochemical reactions. Through analyzing the change in the S 2 p binding energy, we found that the anionic structures of both air-exposed and delithiated sulfides were altered owing to Li-ion loss. Considering the high diffusivity and massive hydrate formation ability of Li ions, we found that the anionic structures of both air-exposed and delithiated sulfides were altered. We showed that the hydrolysis of sulfide SEs with anionic polymerization has a thermodynamically favorable final state energy of −3.85 eV because S ions offer high degrees of freedom in their charge states ranging from −0.89 to −0.31e.