Inspired by helical or spiral veins, which endow plants with excellent flexibility and elasticity to withstand storms, we present novel hollow microsprings with ionic liquid encapsulation for flexible and stretchable electronics. The microsprings were generated by using a coaxial capillary microfluidic device to consecutively spin poly(vinylidene fluoride) (PVDF) presolution and an ionic liquid, which formed laminar flows in the coaxial injection microfluidic channels. The fast phase inversion of PVDF helps to form the core-shell structure of a microfiber and guarantees the in situ encapsulation of ionic liquid. The hybrid microfiber can then spiral and be further solidified to maintain the helical structure with increasing flow rates of the injection fluids. Because of the feasible and precise control of the injection fluids during the microfluidic spinning, the resultant microsprings have controlled core-shell structures, helical pitches, and corresponding electromechanical properties. By further embedding them into stretchable films, the simple paradigm of a flexible device shows great conductive performance in tensile tests and even motion cycles, which could be explored as a promising candidate in stretchable sensors, flexible electronics, and electronic skins.
Li Zeng,Wenbin Kang,Xingang Liu,Hanna He,Xiaolong Li,Chuhong Zhang
The rigorous demand for significantly enhanced performance gains in metrics of areal and volumetric energy density from futuristic energy storage devices is driving current technological endeavors towards the design of highly-loaded energy storage systems. The advancement of supercapacitors has faced a formidable challenge in reconciling ultra-high areal (>1 mWh cm −2 ) and volumetric performance (>10 mWh cm −3 ) due to the intricate issue of efficient mass transport in a highly loaded environment. Here, the capability of 3D printing technology to architect open frameworks is well leveraged in conjunction with material interface decoration to create a heavily loaded pseudocapacitive MnO 2 electrode of low structural tortuosity and fast surface reaction. By harnessing the potential of self-assembly, a robust electrode composed of ubiquitous micro-springs is developed, permitting elastic strain engineering that exceptionally augmented the volumetric performance while preserving efficient mass transport pathways for reasonable kinetics. Coupling with these features, a groundbreaking achievement is attained as an individual supercapacitor unit now boasts an unprecedented ultrahigh areal energy density of 2.83 mWh cm −2 and volumetric energy density of 37.3 mWh cm −3 . The proposed strategy provides an informative roadmap benefiting the construction of next-level electrochemical energy storage devices.
危险品化学品经营许可证（带存储）