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Injectable cell-based hydrogels allow surgical operation in a minimally invasive way for articular cartilage lesions but the chondrocytes in the injectable hydrogels are difficultly arrayed and fixed at the site...

Supercapacitors (SCs) are promising for powering mobile devices, electric vehicles and smart power grids due to their fast charge/discharge rate, high power capability and robust cycle stability. Nitrogen-doped porous carbons are great alternatives because they provide pseudocapacitance without losing their power rate. Nanoporous carbon derived from metal organic frameworks (MOFs) is an ideal precursor for preparing heteroatom-doped carbons due to their abundant nitrogen contents and incredible specific surface areas. However, severe aggregations and the leakage of nitrogen can occur during harsh carbonization. In this study, we used CoAl-LDH (cobalt aluminum layered double hydroxide) as an in-situ growth substrate, allowing Co-based MOF to uniformly grow onto the CoAl-LDH to form a sandwiched MOF/LDH/MOF structure. After acid etching, we obtained waffle-like nanoporous carbons (WNPC). WNPC exhibited high nitrogen and oxygen retention (7.5 wt% and 9.1 wt%) and a broad mesopores distribution with specific surface areas of 594 m2g−1, which promoted a sieving effect. This renders a specific capacitance of 300.7 F·g−1 at 1 A·g−1 and the high retention (72%) of capacitance at 20 A·g−1, ensuring its use at high-rate supercapacitor electrodes. Finally, the WNPC symmetric supercapacitor reaches a superior specific energy of 27 W·h·kg−1 at a power of 500 W·kg−1, and a good cycle stability (85% capacitance retention after 10,000 cycles).

Due to the ongoing development of portable/mobile electronics, sources to power have received widespread attention. Compared to chemical batteries as power sources, triboelectric nanogenerators (TENGs) possess lots of advantages, including the ability to harvest energy via human motions, flexible structures, environment‐friendliness, and long‐life characteristics. Although many self‐healable TENGs are reported, the achievement of a muscle‐like elasticity and the ability to recover from inevitable damage under extreme conditions (such as a high/low temperature and/or humidity) remain a challenge. Herein, a “double‐terminal aromatic disulfide” on a structure with zwitterions as branched chains is reported to engineer the high‐efficient self‐healable elastomer for application in a flexible TENG. The as‐designed material exhibits a repeatable elastic recovery (at 250% elongation) and a self‐healing efficiency with an ultimate tensile stress of 96% over 2 h, representing an improvement on previously reported disulfide‐based elastomers. The elastomer can autonomously recover by 50% even at a subzero temperature of −30 °C within 24 h. The elastomer‐based TENG, as a self‐driven sensor for detecting human behavior, is demonstrated to exhibit stable outputs and self‐healing in the temperature range of −30 to 60 °C, and so is expected to promote the development of self‐powered electronics for next‐generation human–machine communications.