A synchronous-twisting method to realize radial scalability in fibrous energy storage devices

For wearable electronics, radial scalability is one of the key research areas for fibrous energy storage devices to be commercialized, but this field has been shelved for years due to the lack of effective methods and configuration arrangements. Here, the team presents a generalizable strategy to realize radial scalability by applying a synchronous-twisting method (STM) for synthesizing a coaxial-extensible configuration (CEC). As examples, aqueous fiber-shaped Zn-MnO2 batteries and MoS2-MnO2 supercapacitors with a diameter of ~500 μm and a length of 100 cm were made. Because of the radial scalability, uniform current distribution, and stable binding force in CEC, the devices not only have high energy densities (~316 Wh liter−1 for Zn-MnO2 batteries and ~107 Wh liter−1 for MoS2-MnO2 supercapacitors) but also maintain a stable operational state in textiles when external bending and tensile forces were applied. The fabricating method together with the radial scalability of the devices provides a reference for future fiber-shaped energy storage devices.Fil: Zhou, Zhenyu. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Xie, Sijie. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Cai, Heng. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Colli, Alejandro Nicolás. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Programa de Electroquímica Aplicada e Ingeniería Electroquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Monnens, Wouter. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Zhang, Qichong. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Guo, Wei. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Zhang, Wei. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Han, Ning. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Pan, Hongwei. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Zhang, Xueliang. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Pan, Hui. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Xue, Zhenhong. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Zhang, Xuan. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Yao, Yagang. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Zhang, Jin. Ku Leuven. Department Of Materials Engineering; BélgicaFil: Fransaer, Jan. Ku Leuven. Department Of Materials Engineering; Bélgic

Research on performance evaluation and optimization theory for thermal microscope imaging systems

Infrared imaging theory is an important theoretical basis for the design of infrared imaging systems, but there is no research on infrared imaging theory for designing thermal microscope imaging systems. Therefore, we studied the performance evaluation and optimization theory of thermal microscope imaging systems. In this paper, we analyzed the difference in spectral radiant flux between thermal microscope imaging and telephoto thermal imaging. The expression of signal-to-noise ratio of the output image of the thermal microscope imaging systems was derived, based on the analysis of the characteristics of thermal microscope imaging. We studied the performance evaluation model of thermal microscope imaging systems based on the minimum resolvable temperature difference and the minimum detectable temperature difference. Simulation and analysis of different detectors (ideal photon detector and ideal thermal detector) were also carried out. Finally, based on the conclusion of theoretical research, we carried out a system design and image acquisition experiment. The results show that the theoretical study of thermal microscope imaging systems in this paper can provide reference for the performance evaluation and optimization of thermal microscope imaging systems

Adaptive position calibration technique for an optical micro-scanning thermal microscope imaging system

In order to improve the spatial resolution of an optical micro-scanning thermal microscope system, the micro-scanning position must be accurately calibrated. An adaptive calibration method based on image registration and plane coordinate system is proposed. The meaning of calibration is given, and the principle and method of point calibration are introduced in detail and experiments using the real system were done. Different reconstruction methods were applied to reconstruct the visible light image and the real thermal microscope image, and the evaluation scores are given. Results of simulation and real thermal imaging processing show that the method can successfully calibrate the micro-scanning position. The method can significantly improve the oversampled reconstructed image quality, thus enhancing the spatial resolution of the system. This method can also be used in other electro-optical imaging systems

In Situ Polymer Gel Electrolyte in Boosting Scalable Fibre Lithium Battery Applications

Highlights Stable interfaces were successfully achieved through designing channel structures in electrodes to sufficiently incorporate polymer gel electrolyte fabricated through in situ polymerization. The resultant fibre lithium battery (FLB) demonstrated superior energy density output of 128 Wh kg−1 and enabled scalable production capability. Such high-performance FLBs presented prospect applications in diverse scenarios, for example, firefighting, space exploration, and human–computer interaction, even under harsh environments

Shape Effect Analysis of the Mechanical Properties of PVC-Coated Fabrics under Off-Axis Tension

This paper selects polyvinyl chloride- (PVC-) coated fabrics to study its off-axial tensile behaviors under different off-axis angles including 0°, 15°, 30°, 45°, 60°, 75°, and 90°. In the experiment, dumbbell-shaped and strip-shaped specimens are analyzed for shape effect. The variations in the strain distribution are studied by using digital image correlation (DIC) noncontact full-field measurement system. The shape and off-axis angle of specimens are analyzed to predict the influences of shape effect. The results show that the longitudinal strain and shear strain of the coated fabrics are obviously symmetrical to the off-axis direction. The shear strain distribution of the two kinds is basically the same, but the longitudinal strain fields are different. The off-axis tensile properties of the material are obviously anisotropic and nonlinear. The tensile testing curve of the specimens mainly consists of three stages: initial linear stage, deformation strengthening stage, and stress strengthening stage. At 0°, the tensile strength is the largest and the elongation at break is the smallest. In contrast, at 45°, the elongation at break is the highest and the tensile strength was the smallest. The properties under the other off-axis angles were between these two extremes

Flexible quasi-solid-state 2.4 V aqueous asymmetric microsupercapacitors with ultrahigh energy density

Extensive research efforts have recently been devoted to the development of high-energy-density flexible microsupercapacitors (MSCs) to satisfy the rapidly increasing demands for wearable and portable electronics. However, the widespread application of MSCs in high-energy-consuming personal electronic devices has been hindered by their low operating voltages and unsatisfactory specific capacitances. Here, we demonstrate a simple and cost-effective cut-and-transfer method to fabricate flexible quasi-solid-state 2.4 V aqueous asymmetric MSCs (AMSCs) by employing hierarchical Na-MnOx nanosheets on 3D nitrogen-doped carbon fibers as the positive electrode and VN nanosheet arrays as the negative electrode. The resulting AMSCs take advantage of the high specific capacitance and wide electrochemical potential spectrum of the electrode materials to yield a remarkable specific capacitance of 109.5 mF cm−2 and admirable energy density of 87.62 μW h cm−2, outperforming most previously reported MSCs. Thus, this work provides a new way to develop high-voltage aqueous AMSCs for next-generation wearable energy-storage devices.MOE (Min. of Education, S’pore)Accepted versio

All-metal phosphide electrodes for high-performance quasi-solid-state fiber-shaped aqueous rechargeable Ni-Fe batteries

Aqueous secondary Ni-Fe batteries with superior energy density, cost-effectiveness, and outstanding safety contribute significantly toward the development of portable and wearable energy storage devices with high performance. However, the common electrode materials are nickel/iron or their oxides which have suffered from poor conductivity and cycle performance. As an ideal candidate to address these issues, metal phosphides may offer outstanding theoretical specific capacity, low conversion potential, and impressive redox. In this study, one novel type of high-performance flexible Ni-Fe battery with binder-free electrodes on conductive fiber substrates is successfully designed and fabricated. Carbon nanotube fibers with the direct grown hierarchical NiCoP nanosheet arrays and FeP nanowire arrays are fabricated first using hydrothermal synthesis and then the pursuant gas phosphating process. With the assistance of the PVA-KOH gel electrolyte, our fiber-shaped aqueous rechargeable battery (FARB) presents negligible capacity loss after bending 3000 times. Meanwhile, the assembled FARB has a significant capacity of 0.294 mA h/cm2 under the current density of 2 mA/cm2 and a high energy density of 235.6 μW h/cm2.Ministry of Education (MOE)Monetary Authority of SingaporeSubmitted/Accepted versionThis work was supported in part by the Singapore Ministry of Education Academic Research Fund Tier 2 (MOE2015-T2-2- 010) and Singapore Ministry of Education Academic Research Fund Tier 1 (MOE2019-T1-001-103 and MOE2019-T1-001- 111). This work was also supported in part by Nanyang Technological University and the EEE Ignition Research Grant

Self-powered multifunctional sensing based on super-elastic fibers by soluble-core thermal drawing

The well-developed preform-to-fiber thermal drawing technique owns the benefit to maintain the cross-section architecture and obtain an individual micro-scale strand of fiber with the extended length up to thousand meters. In this work, we propose and demonstrate a two-step soluble-core fabrication method by combining such an inherently scalable manufacturing method with simple post-draw processing to explore the low viscosity polymer fibers and the potential of soft fiber electronics. As a result, an ultra-stretchable conductive fiber is achieved, which maintains excellent conductivity even under 1900% strain or 1.5 kg load/impact freefalling from 0.8-m height. Moreover, by combining with triboelectric nanogenerator technique, this fiber acts as a self-powered self-adapting multi-dimensional sensor attached on sports gears to monitor sports performance while bearing sudden impacts. Next, owing to its remarkable waterproof and easy packaging properties, this fiber detector can sense different ion movements in various solutions, revealing the promising applications for large-area undersea detection.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)Nanyang Technological UniversityNational Research Foundation (NRF)Published versionThis work was supported by the Singapore Ministry of Education Academic Research Fund Tier 2 (MOE2019-T2-2-127 and T2EP50120-0005), A*STAR under AME IRG (A2083c0062), the Singapore Ministry of Education Academic Research Fund Tier 1 (RG90/19 and RG73/19), and the Singapore National Research Foundation Competitive Research Program (NRF-CRP18-2017-02). We thank the Nippon Synthetic Chemical Industry Co., LTD (Nippon Gohsei) for offering us the thermal processable PVA pellets (G-polymer) and giving us suggestions about this material in processing. We thank Yu Zheng for helping us take demonstration photos