Electrochemical supercapacitors (SC) with high power and long cycle life have been extensively studied and applied in certain areas. However, a majority of the efforts have been devoted to developing ...SCs with improved performance through novel electrode/electrolytes design. The full mechanistic understanding of SCs based on different electrode materials has not yet been realized. In addition, exploration of new functions for SCs to widen their applications must be accelerated. In this essay, the use of advanced characterization methods (in situ X‐ray diffraction, in situ X‐ray scattering, in situ atomic force microscopy, in situ nuclear magnetic resonance, in situ Raman/infrared spectroscopy, electrochemical quartz crystal microbalance, scanning electrochemical microscopy, etc.) to unveil the electrochemical process of SCs from different aspects will be discussed. The working principles, information to be extracted, and case studies of respective methods will be presented. The multipronged mechanism studies of electrode properties inspire and enable exploration of extra functions within the same electrochemical SCs. Realization of mechanically deformable, low‐temperature, color tunable, self‐healable, and self‐chargeable SCs; integrated SC‐sensors; and SC‐actuators with adoption of new electrode/electrolyte/current collectors/configurations are showcased. The remaining issues hindering the wide exploitation of SCs and the future development trend of SCs are also discussed.
Electrochemical supercapacitors store charge via a complex process involving structural, chemical, and electrochemical variations, which can be unveiled through multiple characterization techniques categorized in this essay. Understanding the relevant mechanisms builds the basis for construction of multifunctional supercapacitors that integrate deformability, self‐healability, sensing, actuation, electrochromism, low‐temperature toleration, and self‐chargeability.
•Latest researches on battery liquid cooling system are summarized from three aspects.•Properties and applications of different liquids are compared.•Advantages and disadvantages of the different ...configurations are analyzed.•Differences in the design scheme between direct and indirect cooling system is compared.•Influences on the cooling performance of battery pack are discussed in depth.
As the power lithium-ion batteries are applied to provide energy for electric vehicles, higher requirements for battery thermal management system (BTMS) have been put forward. The operating temperature, reliability, safety and cycle life of batteries is the key points that people concern. The liquid cooling system is considered as an efficient cooling method, which can control the maximum temperature of the battery and the temperature difference between the batteries in a reasonable range to prolong the cycle life of the battery. This review summarizes the latest research papers of battery liquid cooling system from three aspects, including the performance of coolant, classification of liquid cooling system and design of battery pack. In terms of coolants, the properties and applications of different liquids such as water and oil, as well as different additives such as nanoparticles, are compared. For the classification of liquid cooling system, the difference between active and passive cooling, internal and external cooling, direct and indirect cooling are introduced. As for the design of battery pack, the series, parallel and series-parallel configurations are introduced and the advantages and disadvantages of the different configurations are analyzed. The differences in the design scheme between direct and indirect cooling system are compared. The influences on the cooling performance of battery pack with different parameter design of the cooling plate and the cooling jacket of indirect cooling system are discussed in depth.
Efficient solar evaporation plays an indispensable role in nature as well as the industry process. However, the traditional evaporation process depends on the total temperature increase of bulk ...water. Recently, localized heating at the air–water interface has been demonstrated as a potential strategy for the improvement of solar evaporation. Here, we show that the carbon-black-based superhydrophobic gauze was able to float on the surface of water and selectively heat the surface water under irradiation, resulting in an enhanced evaporation rate. The fabrication process of the superhydrophobic black gauze was low-cost, scalable, and easy-to-prepare. Control experiments were conducted under different light intensities, and the results proved that the floating black gauze achieved an evaporation rate 2–3 times higher than that of the traditional process. A higher temperature of the surface water was observed in the floating gauze group, revealing a main reason for the evaporation enhancement. Furthermore, the self-cleaning ability of the superhydrophobic black gauze enabled a convenient recycling and reusing process toward practical application. The present material may open a new avenue for application of the superhydrophobic substrate and meet extensive requirements in the fields related to solar evaporation.
In the present study we elucidate the nature of local strain statistics evolution during tensile deformation in polycrystalline materials. A rate-independent formulation was implemented within a ...crystal plasticity framework by the means of representative volume element (RVE) analysis. Local elastic strain, as well as stress, were found to obey a normal distribution, whereas the statistics of local plastic strain conforms to a lognormal distribution. In line with experimental observations, the plastic strain becomes progressively localised and the local regions of large strains make significant contribution to the overall average strain increase. The results reveal the nature of strain inhomogeneity at the microscale and emphasize the fact that in metallic materials the elastic strain accumulation represents an additive process, whereas plastic deformation is a multiplicative process.
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Extremely stretchable self‐healing strain sensors based on conductive hydrogels are successfully fabricated. The strain sensor can achieve autonomic self‐heal electrically and mechanically under ...ambient conditions, and can sustain extreme elastic strain (1000%) with high gauge factor of 1.51. Furthermore, the strain sensors have good response, signal stability, and repeatability under various human motion detections.
Antimony selenide (Sb
Se
) has a one-dimensional (1D) crystal structure comprising of covalently bonded (Sb
Se
)
ribbons stacking together through van der Waals force. This special structure results ...in anisotropic optical and electrical properties. Currently, the photovoltaic device performance is dominated by the grain orientation in the Sb
Se
thin film absorbers. Effective approaches to enhance the carrier collection and overall power-conversion efficiency are urgently required. Here, we report the construction of Sb
Se
solar cells with high-quality Sb
Se
nanorod arrays absorber along the 001 direction, which is beneficial for sun-light absorption and charge carrier extraction. An efficiency of 9.2%, which is the highest value reported so far for this type of solar cells, is achieved by junction interface engineering. Our cell design provides an approach to further improve the efficiency of Sb
Se
-based solar cells.
In this paper, a multi-stage deep learning blood pressure prediction model based on imaging photoplethysmography (IPPG) signals is proposed to achieve accurate and convenient monitoring of human ...blood pressure. A camera-based non-contact human IPPG signal acquisition system is designed. The system can perform experimental acquisition under ambient light, effectively reducing the cost of non-contact pulse wave signal acquisition while simplifying the operation process. The first open-source dataset IPPG-BP for IPPG signal and blood pressure data is constructed by this system, and a multi-stage blood pressure estimation model combining a convolutional neural network and bidirectional gated recurrent neural network is designed. The results of the model conform to both BHS and AAMI international standards. Compared with other blood pressure estimation methods, the multi-stage model automatically extracts features through a deep learning network and combines different morphological features of diastolic and systolic waveforms, which reduces the workload while improving accuracy.
The environment design of qualification test of C919 civil aircraft flight can provide tools and means for the electronic identification test of C919 main flight control,and provide the supporting ...data and proof materials for the airworthiness inspection of the airborne equipment. The necessary of qualification test of C919 civil aircraft flight control system and the main qualification test types are introduced,and the qualification test of C919 civil aircraft flight control system is designed,which includes the main test environment composition,design of function,test scheduling and monitoring logic. The design results of qualification test of civil aircraft flight control system are tested and evaluated. The results show that the proposed design can satisfy the qualification test requirement of civil aircraft,be easy for engineering realization,and the data process algorithm and identification report can support the airworthiness conformation requirement.
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