Metal-organic frameworks (MOFs) hold promising potential in energy storage but are limited by poor conductivity. In this work, a metal-organic framework/polypyrrole hybrid is constructed by a facile one-pot electrodeposition method in the presence of dopamine. An all-solid-state fabric supercapacitor based on this hybrid demonstrates excellent electrochemical energy-storage performance, which achieves a specific capacitance of 10 mF cm (206 mF cm), a power density of 132 μW cm (2102 μW cm), and an energy density of 0.8 μWh cm (12.8 μWh cm). The stable cycling life and excellent mechanical flexibility over a wide range of working temperature are also achieved, which maintains a capacitance retention of 89% over 10 000 charging/discharging cycles, a capacitance decrease of only 4% after 1000 frizzy (360° bending) cycles, and no obvious capacitance loss under 100 repeated heating (100 °C)/cooling (-15 °C) cycles. This fibrous supercapacitor displays promising potential in wearable textile electronics as it can be easily woven into common cotton cloth. Our strategy may shed some valuable light on the construction of MOF-based hybrids for flexible energy-storage electronics.
ABSTRACT:The ion exchange behavior of polypyrrole (PPy) doped with a variety of dopants (A), namely chloride, nitrate, para-toluene sulfonate (pTS À ), and dodecyl sulfonate (DS À ), was investigated by means of cyclic voltammetry (CV) in NaCl, NapTS, and AlCl 3 aqueous solutions. The results show that PPy/pTS and PPy/DS films had the best anion and cation exchange ability, respectively. However, the ion exchange ability evaluated by CV charge cannot describe the exact amount of exchanged ions. For that reason, a new ion exchange experiment was designed to evaluate the amount of ions removed from NaCl aqueous solution to AlCl 3 or NapTS aqueous solution. In addition, the ion exchange ratio is defined as the ratio of the charge associated with ion ejection to the synthesis charge, and can be conveniently converted to operating exchange capability (OEC). The ion exchange ratio and OEC can be used to characterize and evaluate the ion exchange ability of PPy/A films in different conditions.
The performance of the selected inhibitors, including thioglycolic acid (TGA), diethylenetriamine (DETA), and naphthene acid imidazolines (IM), on the bare surface of N80 steel and its scaled surface pre-corroded in CO 2 -saturated 1%NaCl solution was investigated by weight-loss method, electrochemical measurements using rotating cylinder electrode and surface analytical methods (SEM, XRD, and EPMA). The results indicate that there is a remarkable difference in inhibition efficiency of inhibitors on the N80 steel with and without precorrosion scale. The synergistic effect between inhibitors and corrosion scale not only depends on the size of inhibitor molecules, but also depends on the interaction of the inhibitor with the corrosion scale. It shows that IM and DETA have a good positive synergistic effect with the corrosion scale formed on N80 steel, although DETA has no inhibition efficiency for bare N80 steel, which can easily enter into the apertures of the corrosion scale, and block the active sites on the metal surface and the diffusion routeways of the reactant so as to depress the corrosion of the substrate metal. While TGA shows excellent inhibition efficiency on bare N80 steel, but it has an antagonistic effect with the corrosion scale although it has a small molecular weight as well as DETA, because TGA can dissolve corrosion scale and break its integrality and protectiveness performance.
Electrochemical migration (ECM) behaviors of tin under unsteady state electric field were investigated via thin electrolyte layer (TEL) method using optical and electrochemical techniques. Unipolar square waves with various time periods and duty cycles were first used as the unsteady state electric field for ECM investigation, where a 3-V-bias and a 0-V-bias were applied across the two electrodes during the ON time and OFF time, respectively. The results show that there is a reverse polarization applied across the two electrodes during the OFF time to ensure the 0-V-bias. The presence of reverse polarization will result in ions migration reverse to their original migration direction and the tin ions that migrated back may even be reduced back to metal tin. Therefore, the reverse polarization is adverse to the ECM process of tin. At the same time period, the rate of dendrites growth increases with the increase of duty cycle. While, for the same duty cycle, the prolongation of time period is favorable for the precipitates formation and/or dendrites growth. The influence mechanisms of time period and duty cycle on ECM behaviors have also been proposed, respectively.Electrochemical migration (ECM), which poses a great threat to the reliability of electronic devices, has attracted considerable attentions. 1-3 This process occurs when two oppositely biased and closely spaced electrodes are connected by a continuous aqueous electrolyte layer. During ECM, metal will dissolve at the anode and then the dissolved metal cations migrate toward the negatively charged cathode, where they can be reduced to metallic dendrites and grow toward anode. Ultimately, such a dendrite can lead to a short circuit as soon as it reaches the anode, thus cause catastrophic failure of electronic devices.ECM has been widely investigated regarding the test methods and its influencing factors. Up to now, there are three common test methods for ECM investigations. The first one is the droplet test (sometimes called water drop test), which can be performed rapidly and is suitable for quantitative investigations. 1-6 The second one is the simulated environment experiment (such as thermal humidity bias test (THB) and highly accelerated stress test (HAST)). 7-10 This method is the most practical way because it can well simulate the environmental conditions that the electronic devices are in service. The last one is the thin electrolyte layer (TEL) test proposed by our group, which is more suitable for quantitative real time in situ study with a good reproducibility. 11,12 ECM behaviors are mainly influenced by materials, solution chemistry and electric field. The ECM behaviors of Sn and its alloys have attracted considerable attentions due to their significant roles as conducting or welding materials in electronic devices. 1-18 Each material has its own migration characteristic and mechanism. As another key factor in ECM behaviors of materials, solution chemistry, such as the concentration of the aggressive ions, 11,12,17 the species categories includi...
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