Microdevice integrating energy storage with wireless charging could create opportunities for electronics design, such as moveable charging. Herein, we report seamlessly integrated wireless charging ...micro-supercapacitors by taking advantage of a designed highly consistent material system that both wireless coils and electrodes are of the graphite paper. The transferring power efficiency of the wireless charging is 52.8%. Benefitting from unique circuit structure, the intact device displays low resistance and excellent voltage tolerability with a capacitance of 454.1 mF cm
, superior to state-of-the-art conventional planar micro-supercapacitors. Besides, a record high energy density of 463.1 μWh cm
exceeds the existing metal ion hybrid micro-supercapacitors and even commercial thin film battery (350 μWh cm
). After charging for 6 min, the integrated device reaches up to a power output of 45.9 mW, which can drive an electrical toy car immediately. This work brings an insight for contactless micro-electronics and flexible micro-robotics.
Flexible power supplies that can harvest power from an ambient environment are of considerable interest for future portable electronics. However, the complex structure and costly functional material ...of current power generators hinder their further development and practical application. Here we demonstrate flexible, all-printable graphene oxide (GO) functionalized paper as a moisture-electric power generator with an induced voltage of up to 2 V. Such high voltage is achieved by asymmetric moisturizing of GO, which enables directional ion migration across the GO. This work demonstrates a low-cost, scalable, lightweight and bendable power generator, opening up new possibilities for significantly expanding the application domain of graphene and reducing the cost of portable electronics.
The development of compressible supercapacitors (SCs) that is tolerant to wide temperature range has been severely hindered due to the poor ionic conductivity and absence of extra functions in ...conventional polymer electrolytes. Herein, a highly conductive and compressible hydrogel polyelectrolyte has been prepared from polyacrylamide cross-linked by methacrylated graphene oxide (MGO-PAM) and the polyelectrolyte can maintain its excellent elasticity at −30 °C as well as its original shape at 100 °C. As a result, the SC based on the MGO-PAM polyelectrolyte outperformed those fabricated with the conventional poly(vinyl alcohol) (PVA)/H
2
SO
4
electrolyte over a wide temperature window between −30 and 100 °C. Meanwhile, the device shows an excellent cycling stability (capacitance retention of 93.3% after 8,000 cycles at −30 °C and 76.5 % after 4,000 cycles under 100 °C) and a reversible compressibility (a high capacitance retention of 94.1% under 80% compression). Therefore, the MGO-PAM polyelectrolyte enables the fabrication of compressible SCs with a wide operating temperature, rendering new insights for developing next-generation robust and multifunctional energy-storage devices.
Abstract
Photoelectrochemical reaction is emerging as a powerful approach for biomass conversion. However, it has been rarely explored for glucose conversion into value-added chemicals. Here we ...develop a photoelectrochemical approach for selective oxidation of glucose to high value-added glucaric acid by using single-atom Pt anchored on defective TiO
2
nanorod arrays as photoanode. The defective structure induced by the oxygen vacancies can modulate the charge carrier dynamics and band structure, simultaneously. With optimized oxygen vacancies, the defective TiO
2
photoanode shows greatly improved charge separation and significantly enhanced selectivity and yield of C
6
products. By decorating single-atom Pt on the defective TiO
2
photoanode, selective oxidation of glucose to glucaric acid can be achieved. In this work, defective TiO
2
with single-atom Pt achieves a photocurrent density of 1.91 mA cm
−2
for glucose oxidation at 0.6 V versus reversible hydrogen electrode, leading to an 84.3 % yield of glucaric acid under simulated sunlight irradiation.
Thin-walled parts are widely applied in the automotive and aerospace industry for their superior properties. However, severe machining error may occur due to their low rigidity under the effects of ...multiple error sources in the machining process. Solutions based on mechanism analysis and finite element method have been developed while most of them are not robust under the complex machining conditions. Aiming to solve this problem, a comprehensive error compensation method that includes three major error sources, which are geometric error, thermal error, and force-induced error, is proposed. The geometric error and thermal-induced error of the machining center are firstly modeled and compensated to provide a high precision movement system for the on-machine measurement inspection. The force-induced error model is then established based on the probing data. Finally, the comprehensive error model is obtained through the transformation of the coordinate systems. Besides, a real-time compensation system is developed based on the specific functions of the NC system. To validate the proposed method, two sets of compensation cases are conducted, the objects of which are a thin web workpiece and a valve body part, respectively. The experiment results reveal that the machining errors of both experiment sets are decreased by more than 60.7% and the machining productivity is improved by more than 41.9%.
The emerging flexible electronic devices have stimulated the development of flexible batteries, in which flexible electrodes are indispensable components. Graphene, known for its excellent electrical ...conductivity and mechanical stability, can be used as an ideal flexible substrate. Recently, many efforts have been devoted to graphene‐based electrodes for flexible batteries. Herein, this review summarizes recent advances in the development of graphene‐based electrodes for various flexible batteries, including metal‐ion batteries (ions of Li, Na, Zn, Al, etc.), lithium‐sulfur batteries, and metal‐air batteries (Li‐ and Zn‐air batteries). Besides, major challenges and future developments of flexible batteries are also discussed.
This review summarizes recent advances in the development of graphene‐based electrodes for various flexible batteries, including metal‐ion batteries (ions of Li, Na, Zn, Al, etc.), lithium‐sulfur batteries, and metal‐air batteries (Li‐ and Zn‐air batteries). Besides, major challenges and future developments of flexible batteries are also discussed.
Phonon engineering is a core stratagem to improve the thermoelectric performance, and multi-scale defects are expected to scatter a broad range of phonons and compress the lattice thermal ...conductivity. Here, we demonstrate obviously enhanced thermoelectric properties in Bi0.48Sb1.52Te3 alloy by a hot-pressing texture method along the axial direction of a zone-melted ingot. It is found that a plastic deformation of grain refinement and rearrangement occurs during the textured pressing process. Although the obtained power factor is slightly decreased, a large amount of grain boundaries emerges in the textured samples and dense dislocations are observed around the boundaries and inside the grains. These additional phonon scattering centers can effectively scatter the low- and mid-frequency phonons, and the corresponding lattice thermal conductivity is significantly reduced to only 50% of that of zone-melted samples. Consequently, the maximum figure of merit (ZT) reaches 1.44 at 330 K and the average ZT (300–380 K) reaches 1.38. This study suggests that the simple hot-pressing texture technique is a promising method to significantly optimize the cooling capacity of Bi0.48Sb1.52Te3-based thermoelectric refrigeration.
The recent decade has witnessed wild swings in International Energy price, and there is no doubt that a large fluctuation in energy prices will have an impact on a country’s macro economy. This study ...examines the impact of international energy price on Romanian macroeconomic –CPI, exchange rate and industrial product – by using Granger causality test and quantiles regression. We find that the international energy price can affect the CPI and industrial product of Romania, while it can’t influence exchange rate at all. Also when energy price increase and decrease, it will have different impact on Romanian macroeconomic.
Private enforcement of competition law should focus not only on damages and compensation but also on deterrence as an equal objective. The book provides an in-depth comparison of law and practice in ...the EU, Germany, and China, illustrating the different but complementary roles of nullity of restrictive agreements, injunctive relief, and damages actions in private enforcement. It concludes with approaches for enhancing private enforcement within a dual-goal framework and suggests targeted improvements for Chinese competition law enforcement. The book provides valuable insights into judicial practice and the recent amendment of China’s Antimonopoly law.
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