ABSTRACT
Green energy from the surrounding environment has great potential for reducing environmental pollution and sustainable development. Triboelectric nanogenerators (TENGs) are of great interest as they can easily harvest mechanical energy from the environment. Here, we present a triboelectric nanogenerator (RS-TENG) based on rape straw (RS), which was developed from a film composed of waste RS and polyvinyl alcohol (PVA). Due to the high content of carbonyl, hydroxyl and amino acid functional groups in RS, the ability of RS/PVA to lose electrons is increased. The proposed RS-TENG device with a size of 6.25 cm2exhibits open circuit voltage (78 V), short circuit current (5.3µA) performance under uniform external stress at a frequency of 3.5 Hz and 10 N in the cylinder motor. 104.5µW was obtained with a load resistance of 25 MΩ. Results obtained from degradability tests revealed that the RS/PVA film was able to degrade over a period of 30 d (In PBS solution). The RS-TENG produces a significantly high current signal under conditions of finger bending, elbow movements, and foot tapping. Practical tests of the RS-TENG have shown that it is a promising sensing device that will be widely used in the future.
Subject(s)
Electrons , Hydroxyl Radical , Humans , Powders , Movement , Polyvinyl AlcoholABSTRACT
Metallized film capacitors (MFCs) are widely used in the power electronics industry due to their unique self-healing (SH) capability. SH performance is an essential assessment for MFC reliability verification in industrial production. The SH phenomenon of metallized films usually occurs rapidly in a very short period, and its real-time evolution details are often difficult to capture and analyze. In this paper, a test system for the SH performance of metallized films for capacitors was constructed. The system consists of three components: a voltage-current characteristic testing and current pulse capture device, a microscopic image real-time acquisition device, and an integrated analysis processing device. Through the voltage-current characteristic testing and current pulse capture device, the electrical parameters of the SH point, such as SH times, breakdown field strength, SH current, and SH energy, are obtained; through a microscopic image real-time acquisition device, the real-time spatial positioning of the SH point was obtained, and the interconnection between the morphology of the SH point and the electrical properties was established. The relationship between the SH point and the temperature distribution was further established using thermal imaging technology, which lays the foundation for a thorough and timely assessment and analysis of the failure mechanism and the real-time evolution of the metallized film SH process. This significantly improves the effectiveness of SH property research.
ABSTRACT
Halide perovskites have gained tremendous attention in the past decade owing to their excellent properties in optoelectronics. Recently, a fascinating property, ferroelectricity, has been discovered in halide perovskites and quickly attracted widespread interest. Compared with traditional perovskite oxide ferroelectrics, halide perovskites display natural advantages such as structural softness, low weight, and easy processing, which are highly desirable in applications pursuing miniaturization and flexibility. This review focuses on the current research progress in halide perovskite ferroelectrics, encompassing the emerging materials systems and their potential applications in ferroelectric photovoltaics, self-powered photodetection, and X-ray detection. The main challenges and possible solutions in the future development of halide perovskite ferroelectric materials are also attempted to be pointed out.
ABSTRACT
The energy storage density of a capacitor depends on its relative permittivity and breakdown strength. Breakdown of a thin film always first occurs at weak defect spots of dielectrics under a high electric field. It is of great significance to study the defect-induced breakdown of dielectrics to improve the breakdown strength of the dielectric. The majority of studies about the defect-induced breakdown only determine a certain voltage inducing the breakdown, and the single-hole breakdown spots influence the defect-induced breakdown and the intrinsic breakdown under a high electric field, which is hard to facilitate the in-depth study of improving the breakdown strength. Herein, the self-healing breakdown techniques are applied to avoid the influence of single-hole breakdown. An automated real-time testing system is used to study the defect-induced breakdown of various complex film-electrode systems, which accomplishes the temporal and spatial localization of breakdown events according to the physical chemistry characteristics of breakdowns and intelligently displays breakdown events, and detailed classification methods of the defect-induced breakdown are discussed concisely and efficiently. This real-time testing system is effective in revealing the defect-induced breakdown of various complex film-electrode systems under a high electric field, paving the way for uncovering the breakdown mechanism and studying how to improve the capacitor's breakdown strength and energy density.