The remaining useful life prediction of supercapacitor is an important part of the supercapacitor management system. In order to improve the reliability of the entire supercapacitor bank, this paper ...proposes a life prediction method based on long short-term memory neural network. It is used to learn the long-term dependence of degraded capacity of supercapacitor. The Dropout algorithm is used to prevent overfitting and the neural network is optimized by the Adam algorithm. The supercapacitor data measured under different working conditions is divided into training set and predictive set as the input of the neural network. The root mean square error of the predicted result is about 0.0261. At the same time, in order to verify the applicability of the algorithm, it is also used for the life prediction of offline data, and the root mean square error is about 0.0338. The overall results show that long short-term memory neural network exhibits excellent performance for remaining useful life prediction of supercapacitor.
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•Long short-term memory neural network is employed for prediction.•Aging experiments at different temperature and work voltage are conducted.•The proposed method is applied to the untrained offline data of life predication.
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•Efficient HGA-LSTM method proposed for predicting life of energy storage devices.•Precise and robust lifetime estimation for Supercapacitors with error low to 1.61%•Low time cost of ...59 min for one remaining life predication, a 60% reduction.•Adaptability for predicting life of supercapacitor at real-time dynamic cycling.•High versatility of such method to deal with both online and offline untrained data.
Supercapacitor as a clean energy storage device has been widely adopted in powering electric motors of vehicles. Precise evaluation of aging state of supercapacitors, i.e., the remaining useful life provides a feedback to replace damaged cells to sustain the comfort and safety of electric vehicle. Currently reported evaluation methods for such aim are data or model-based predications, which are either time consuming or of low precision. To achieve efficient and robust evaluation of the remaining lifetime, this work proposes a general strategy based on the combination between a recurrent neutral network method, i.e., long short-term memory, and hybrid genetic algorithm. The sequential quadratic programming as a local search operator of the genetic algorithm, enhances its global search ability, which allows quickly search for the local optimal solution in the means of the dropout probability and the number of hidden layer units. Eventually we apply this predication method to supercapacitors charging at steady state mode and succeed in estimating their remaining useful life. Such life prediction approach also gains validity in supercapacitors with dynamic operative cycle. Indeed, high accuracy has been achieved at both the online trained supercapacitors with root mean square errors ranging from 0.0161 and 0.0214, and offline historical data with 0.0264 error. Moreover, the estimation time is shortened to 3550 s, which is shortened by 60%. This evaluation model may pave the way in predicting the remaining useful lifetime of supercapacitors as well as secondary ion batteries in a precise and robust fashion.
Sb2Se3 as a rising star semiconducting material with a bandgap of 1.1 eV has played a role of the absorber in the thin film solar cells. Regular device architectures such as metal ...grids/buffer/Sb2Se3/metal electrode, or transparent electrode film/buffer/Sb2Se3/metal electrode have been fabricated both experimentally and theoretically and exhibit relatively good photovoltaic performances. Yet the theoretical power-conversion efficiency is not competitive with commercial thin film solar cells. Therefore, we propose an inverted architecture with top illumination through ITO substrate, with allocating the hole transport layer (HTL) on top of Sb2Se3 and stacking electron transport layer beneath the Sb2Se3. Indeed an optimal power conversion efficiency of 24.7% and fill factor of 80.3% have been simulated in the solar devices with the selected NiO as the HTL. The improvement in solar cell performances stems from the satisfying bandgap alignment and improved hole conductivity due to the high acceptor concentration of the chosen material. Further increase of the device performances depend on the high quality Sb2Se3 thin films, i.e., with negligible defects states and the suppression of defects at the Sb2Se3/HTL interfaces.
Optimal band alignment and device design inverted architecture of Sb2Se3 solar cell ● High NiO as hole transport layer to boost the performances of Sb2Se3 solar cell. ● High quality Sb2Se3 film with defect suppression and improved device performances. Display omitted
•Sb2Se3 solar cells with efficiency of 24.7%, Voc of 858 mV, and fill factor of 84.1% were designed and simulated.•High performance Sb2Se3 solar cells have been achieved using NiO hole transport layer in an inverted device architecture.•Improvement in FF and Voc stemmed from the high acceptor concentration of HTL and the optimized band alignment.•High quality of Sb2Se3 boosted device performances by suppressing its defect states and improving Sb2Se3/HTL interface.
Sb2S3 thin-film solar cells have recently gained attention due to their low cost, low toxicity, and simple fabrication. However, there is still plenty of room to improve their performance. It is ...known that efficient carrier transport is essential for high performance Sb2S3 solar cells, which, unfortunately, is difficult to characterize by conventional testing methods. Therefore, the carrier transport process in Sb2S3 solar cells was studied here using a theoretical simulation. The results show that high solar performances can be achieved with a wide parameter window for selecting the electron transport layer as well as the hole transport layer, viz., with a conduction band minimum of the electron transport layer (−4.4 eV < CBM < −3.2 eV), and a valence band maximum of the hole transport layer (−5.2 eV > VBM > −6.4 eV). Here the interfacial potential barrier become negligible and as a consequence electrons and holes cross at ease, which guarantee the good device performance. Indeed, a Sb2S3 solar cell with a high power conversion efficiency (PCE) can be obtained by ensuring that the carrier transport and collection are unimpeded in the device, i.e., the Sb2S3-based single junction solar cells shows high efficiency of 19.53%. Furthermore, we found that optimized Sb2S3 solar cells are particularly suitable for use as the top cell of tandem structure solar cells. Thus, a Sb2S3/Sb2Se3 double junction solar cell structure was proposed. With a 0.5 μm thick Sb2S3 absorber, double junction solar cells could achieve a theoretical efficiency as high as 26.64%. Our results based on the rotational design of bandgap alignment provide a general guide rule for selecting the optimal electron transport layer as well as the hole transport layer to boost the power conversion efficiency for Sb2S3 solar cells up to its theoretical limit.
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•Sb2S3 solar cells obtained by boosting the carrier transport and collection at absorber/ETL and absorber/HTL interfaces.•A Sb2S3 solar cell with a high efficiency of 19.53% and large Voc of 1.20 V was designed and obtained.•A demonstration of typical high efficiency Sb2S3 solar cell features the architecture of Y/ETL: BCP/Sb2S3/HTL:mCP/Pt.•Sb2S3/Sb2Se3 double junction tandem solar cells can achieve a theoretical efficiency as high as 26.64%.
Carbon nanotubes (CNTs) have attracted great attentions in the field of electronics, sensors, healthcare, and energy conversion. Such emerging applications have driven the carbon nanotube research in ...a rapid fashion. Indeed, the structure control over CNTs has inspired an intensive research vortex due to the high promises in electronic and optical device applications. Here, this in-depth review is anticipated to provide insights into the controllable synthesis and applications of high-quality CNTs. First, the general synthesis and post-purification of CNTs are briefly discussed. Then, the state-of-the-art electronic device applications are discussed, including field-effect transistors, gas sensors, DNA biosensors, and pressure gauges. Besides, the optical sensors are delivered based on the photoluminescence. In addition, energy applications of CNTs are discussed such as thermoelectric energy generators. Eventually, future opportunities are proposed for the Internet of Things (IoT) oriented sensors, data processing, and artificial intelligence.
The improved battery management system (BMS) can give full play to the best performance of power battery, and the state of charge (SOC) estimation of power lithium-ion battery is the core and key ...technology of BMS. The Kalman filter method with the first-order Thevenin model cannot obtain better estimation results because of the limited model precision. Aiming at solving the above problems, this paper presents a second-order Thevenin equivalent circuit model. The idea of the Sage-Husa adaptive algorithm and square root filter is introduced based on the Unscented Kalman Filter (UKF) algorithm. The adaptive square root Unscented Kalman Filter (ASRUKF) algorithm is formed to improve the precision of SOC estimation. Experiments on SOC estimation of the battery are carried out under three different working conditions. The experimental results show that the ASRUKF algorithm under the second-order Thevenin equivalent circuit model can converge quickly and achieve high precision in SOC estimation.
Highlights
The structure–property relationship of PdSe
2
is discussed, i.e., layer number vs. tunable bandgap, pentagonal structure vs. anisotropy-based polarized light detection.
The synthesis ...approaches of PdSe
2
are thoroughly compared, including bottom-up methods such as chemical vapor transport for bulk crystals, chemical vapor deposition for thin films and single-crystal domains, selenization of Pd films. Besides, top-down strategies are discussed, covering the mechanical exfoliation of bulk crystals, plasma thinning, and vacuum annealing as well as phase transition.
The emerging devices of PdSe
2
and its van der Waals heterostructures have been delivered such as metal/semiconductor contact, Schottky junction transistors, field-effect transistors, photodetectors,
p
–
n
junction-based rectifiers, polarized light detector, and infrared image sensors.
Future opportunities of PdSe
2
-based van der Waals heterostructures are given including logic gate-based digital circuits, RF-integrated circuits, Internet of Things, and theoretical calculation as well as big data for materials science.
The rapid development of two-dimensional (2D) transition-metal dichalcogenides has been possible owing to their special structures and remarkable properties. In particular, palladium diselenide (PdSe
2
) with a novel pentagonal structure and unique physical characteristics have recently attracted extensive research interest. Consequently, tremendous research progress has been achieved regarding the physics, chemistry, and electronics of PdSe
2
. Accordingly, in this review, we recapitulate and summarize the most recent research on PdSe
2
, including its structure, properties, synthesis, and applications. First, a mechanical exfoliation method to obtain PdSe
2
nanosheets is introduced, and large-area synthesis strategies are explained with respect to chemical vapor deposition and metal selenization. Next, the electronic and optoelectronic properties of PdSe
2
and related heterostructures, such as field-effect transistors, photodetectors, sensors, and thermoelectric devices, are discussed. Subsequently, the integration of systems into infrared image sensors on the basis of PdSe
2
van der Waals heterostructures is explored. Finally, future opportunities are highlighted to serve as a general guide for physicists, chemists, materials scientists, and engineers. Therefore, this comprehensive review may shed light on the research conducted by the 2D material community.
The emergence of electronic devices has brought earth-shaking changes to people’s life. However, an external power source may become indispensable to the electronic devices due to the limited ...capacity of batteries. As one of the possible solutions for the external power sources, the triboelectric nanogenerator (TENG) provides a novel idea to the increasing number of personal electronic devices. TENG is a new type of energy collector, which has become a hot spot in the field of nanotechnology. It is widely used at the acquisition and conversion of mechanical energy to electric energy through the principle of electrostatic induction. On this basis, the TENG could be integrated with the energy storage system into a self-powered system, which can supply power to the electronic devices and make them work continuously. In this review, TENG’s basic structure as well as its working process and working mode are firstly discussed. The integration method of TENGs with energy storage systems and the related research status are then introduced in detail. At the end of this paper, we put forward some problems and discuss the prospect in the future.
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•The 3D graphene family is introduced along with its different classifications including shells, foams and hydrogels, as well as their fabrication methods.•The 3D graphene family are ...reviewed with their structural, mechanical, electrical, and biocompatible properties.•Their emergent energy, environmental and biomedical applications are reviewed.•A perspective for future challenges and opportunities is offered.
Three-dimensional (3D) nanostructured graphene can be used as a replacement or enrichment material. This review presents the types of 3D graphene developed thus far, for example, nanoshells, encapsulates, graphene foams, aerogels and hydrogels, their properties and the methods by which to obtain them, such as chemical vapour deposition, the hydrothermal method or by sugar-blowing production. The review also covers areas in which 3D graphene foam has been exploited for application such as energy, electronic, biomedical and environmental protection as well as the latest developments.
A flexible, multi-site tactile and thermal sensor (MTTS) based on polyvinylidene fluoride (resolution 50 50) is reported. It can be used to implement spatial mapping caused by tactile and thermal ...events and record the two-dimensional motion trajectory of a tracked target object. The output voltage and current signal are recorded as a mapping by sensing the external pressure and thermal radiation stimulus, and the response distribution is dynamically observed on the three-dimensional interface. Through the mapping relationship between the established piezoelectric and pyroelectric signals, the piezoelectric component and the pyroelectric component are effectively extracted from the composite signals. The MTTS has a good sensitivity for tactile and thermal detection, and the electrodes have good synchronism. In addition, the signal interference is less than 9.5% and decreases as the pressure decreases after the distance between adjacent sites exceeds 200 mm. The integration of MTTS and signal processing units has potential applications in human-machine interaction systems, health status detection and smart assistive devices.
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