series resistance
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Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 273
Author(s):  
Rosa M. González-Gil ◽  
Mateu Borràs ◽  
Aiman Chbani ◽  
Tiffany Abitbol ◽  
Andreas Fall ◽  
...  

A new gel polymer electrolyte (GPE) based supercapacitor with an ionic conductivity up to 0.32–0.94 mS cm−2 has been synthesized from a mixture of an ionic liquid (IL) with nanocellulose (NC). The new NC-ionogel was prepared by combining the IL 1-ethyl-3-methylimidazolium dimethyl phosphate (EMIMP) with carboxymethylated cellulose nanofibers (CNFc) at different ratios (CNFc ratio from 1 to 4). The addition of CNFc improved the ionogel properties to become easily printable onto the electrode surface. The new GPE based supercapacitor cell showed good electrochemical performance with specific capacitance of 160 F g−1 and an equivalent series resistance (ESR) of 10.2 Ω cm−2 at a current density of 1 mA cm−2. The accessibility to the full capacitance of the device is demonstrated after the addition of CNFc in EMIMP compared to the pristine EMIMP (99 F g−1 and 14.7 Ω cm−2).


Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 155
Author(s):  
Joseph M. Gallet de St Aurin ◽  
Jonathan Phillips

A model study of electric double layer capacitor (EDLC)-style capacitors in which the electrodes were composed of low surface area-oriented flakes of graphite that compressed to form a paper-like morphology has suggested that ion transport rates significantly impact EDLC energy and power density. Twelve capacitors were constructed, each using the same model electrode material and the same aqueous NaCl electrolyte, but differing in relative electrode orientation, degree of electrode compression, and presence/absence of an ionic transport salt bridge. All were tested with a galvanostat over a range of discharge currents. Significant differences in energy and power density and estimated series resistance were found as a function of all the factors listed, indicating that capacitor performance is not simply a function of the electrode surface area. This simple postulation was advanced and tested against data: net ion (Na+, Cl−) ‘velocity’ during both charge and discharge significantly impacts capacitive performance.


Nanomaterials ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 46
Author(s):  
Giovanni Landi ◽  
Luca La Notte ◽  
Alessandro Lorenzo Palma ◽  
Andrea Sorrentino ◽  
Maria Grazia Maglione ◽  
...  

Environmentally friendly energy storage devices have been fabricated by using functional materials obtained from completely renewable resources. Gelatin, chitosan, casein, guar gum and carboxymethyl cellulose have been investigated as sustainable and low-cost binders within the electrode active material of water-processable symmetric carbon-based supercapacitors. Such binders are selected from natural-derived materials and industrial by-products to obtain economic and environmental benefits. The electrochemical properties of the devices based on the different binders are compared by using cyclic voltammetry, galvanostatic charge/discharge curves and impedance spectroscopy. The fabricated supercapacitors exhibit series resistance lower than a few ohms and values of the specific capacitance ranged between 30 F/g and 80 F/g. The most performant device can deliver ca. 3.6 Wh/kg of energy at a high power density of 3925 W/kg. Gelatin, casein and carboxymethyl cellulose-based devices have shown device stability up to 1000 cycles. Detailed analysis on the charge storage mechanisms (e.g., involving faradaic and non-faradaic processes) at the electrode/electrolyte interface reveals a pseudocapacitance behavior within the supercapacitors. A clear correlation between the electrochemical performances (e.g., cycle stability, capacitance retention, series resistance value, coulombic efficiency) ageing phenomena and charge storage mechanisms within the porous carbon-based electrode have been discussed.


2021 ◽  
Vol 26 (3) ◽  
Author(s):  
O. V. Tsukanov ◽  
O. H. Dramaretskyi ◽  
Yurii Viktorovych Didenko ◽  
Dmytro Dmytrovych Tatarchuk

When studying the operation of Schottky diodes the most important electrical parameters are the height of the potential barrier, the coefficient of ideality, the saturation current and the series resistance of the material and contacts. These parameters can be determined from the experimental volt-ampere characteristics. The article considers the methods of determining these electrical parameters of Schottky diodes, as well as the factors that affect the accuracy of calculations. The existing methods for calculating the electrical parameters of Schottky diodes are analyzed, namely: the method of Norde, Roderick, Chong, Sato and the method of direct approximation. The Norde method was developed for a coefficient of ideality equal to one for cases where the effect of series resistance on the I–V characteristics makes a significant error in determining the barrier height by simpler methods. A significant disadvantage of this method is that in many cases the coefficient of ideality is not equal to one, even in the case of an ideal diode, which makes an error in the calculation result. The advantage of Roderick's method is the possibility of describing the forward and reverse branches of the I–V characteristics by one dependence, as well as taking into account measurements at voltages less than tripled temperature potential. The disadvantages of this method include the lack of consideration of the effect of series resistance, which may result in additional errors. The main advantage of the Chong method is the determination of the series resistance together with the height of the barrier and the coefficient of ideality, which not only provides additional information about the contact, but also convenient in terms of automation of the calculation process. The disadvantages include the possibility of applying the method only to the voltage range above the tripled temperature potential. The disadvantages of Sato methods and direct approximation include the fact that the calculation is performed at one point of the I–V curve, which can negatively affect the accuracy. It is also shown that these methods have a significant standard deviation of the calculated values from the experimental ones, which is due to the temperature dependence of the height of the potential barrier and the dependence of the coefficient of ideality on the voltage. Also, the reason for the increase in the calculation error of the electrical parameters in all five methods is the decrease in the length of the I–V characteristics in logarithmic coordinates. When using any of the considered methods, the calculation is performed in logarithmic coordinates, which complicates the determination of the boundaries of the I–V section, where the dependence of the parameters of the Schottky diode on the voltage is insignificant. A new algorithm for calculating the electrical parameters of Schottky diodes has been developed. Based on the conjugate gradient method, a method for optimizing the algorithm for calculating the electrical parameters of Schottky diodes was developed, which made it possible to reduce the standard deviation by more than an order of magnitude. The developed algorithm is verified by comparing the calculated volt-ampere characteristics of Schottky diodes with those obtained experimentally. To construct the calculated volt-ampere characteristics, the values of the electrical parameters of Schottky diodes were used, which were determined by the presented algorithm. The results of the calculation are in good agreement with the experimental data. The proposed method can be used both in scientific work to study the properties of semiconductor materials, and in production to control the quality of Schottky diodes.


Author(s):  
Gleb Shevchenko ◽  
Eduard Semenov

The article discusses the key factors influencing the discrepancy between the experimental and model curves when simulating a p – n junction on pulsed broadband signals. The reason for the discrepancy lies in the quasi-static representation of the forward and backward reconstruction of the p – n junction in the standard SPICE model. The quasi-static approximation does not take into account the transient processes in the p – n junction, which are associated with the transit time of minority charge carriers and the series resistance of losses.


Author(s):  
Yusuke Kobayashi ◽  
Tatsuya Nishiwaki ◽  
Akihiro Goryu ◽  
Tsuyoshi Kachi ◽  
Ryohei Gejo ◽  
...  

Abstract Reducing the reverse recovery charge (Qrr) is effective for reducing switching loss in field plate (FP)-MOSFETs. A lifetime killer is utilized to reduce Qrr while increasing the leakage current in the off-state. Device simulation shows that a local lifetime killer on the cathode side successfully improves the trade-off between Qrr and IDSS in comparison with that of a uniform lifetime killer. A known issue of cathode lifetime killers is overshoot voltage by hard recovery. However, the overshoot voltage of FP-MOSFET decreases with a cathode lifetime killer owing to an internal snubber, which is a feature of FP-MOSFETs. An internal snubber with a large series resistance causes dynamic avalanche by both the increase of FP potential and excess carriers in high-speed operation. The cathode lifetime killer also improves dynamic avalanche by excess carriers. Consequently, the cathode lifetime killer is preferable for high-speed FP-MOSFETs.


Author(s):  
Jiawei chen ◽  
yudong li ◽  
Heini Maliya ◽  
Bingkai Liu ◽  
Qi Guo ◽  
...  

Abstract The displacement damage effects of vertical-cavity surface-emitting lasers (VCSELs) irradiated by 3 and 10 MeV protons in the range of Ф = 6.7×1012 p/cm2 to Ф = 1.6×1014 p/cm2 were investigated. The threshold current exhibited consistent degradation at the same displacement damage dose, as did the series resistance. Additionally, the external quantum efficiencies of 850 and 680 nm VCSELs were degraded by 2% and 21%, respectively. Further, the threshold current of the 850 nm VCSEL was restored by 14% after annealing at 20 mA, which is remarkably higher than that achieved by annealing only at high temperatures. These results support the applicability of VCSELs to both data communication and instrumentation applications in harsh radiation environments.


Author(s):  
F. Akbar ◽  
T. Mehmood ◽  
K. Sadiq ◽  
M.F. Ullah

Introduction. With the snowballing requirement of renewable resources of energy, solar energy has been an area of key concern to the increasing demand for electricity. Solar photovoltaic has gotten a considerable amount of consideration from researchers in recent years. Purpose. For generating nearly realistic curves for the solar cell model it is needed to estimate unknown parameters with utmost precision. The five unknown parameters include diode-ideality factor, shunt-resistance, photon-current, diode dark saturation current, and series-resistance. Novelty. The proposed research method hybridizes flower pollination algorithm with least square method to better estimate the unknown parameters, and produce more realistic curves. Methodology. The proposed method shows many promising results that are more realistic in nature, as compared to other methods. Shunt-resistance and series-resistance are considered and diode constant is not neglected in this approach that previously has been in practice. The values of series-resistance and diode-ideality factor are found using flower pollination algorithm while shunt-resistance, diode dark saturation current and photon-current are found through least square method. Results. The combination of these techniques has achieved better results compared to other techniques. The simulation studies are carried on MATLAB/Simulink.


Author(s):  
Kiyoshi Takeuchi ◽  
Tomoko Mizutani ◽  
Takuya Saraya ◽  
Masaharu Kobayashi ◽  
Toshiro HIRAMOTO

Abstract A simple MOSFET series resistance extraction method using multiple drain current vs. gate voltage curves of a single device is proposed, where mobility modulation by horizontal electric field (i.e., weak velocity saturation) is taken into account. The method is validated using TCAD, where series resistance determined from internal potential distributions was used as reliable reference. Measurement results were also obtained which further support the validity of the method.


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