Home  About us  Contact
 

Interfacial Resistance (interfacial + resistance)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Capacity Fading Mechanism in All Solid-State Lithium Polymer Secondary Batteries Using PEG-Borate/Aluminate Ester as Plasticizer for Polymer Electrolytes

ADVANCED FUNCTIONAL MATERIALS, Issue 6 2009
Fuminari Kaneko
Abstract Solid-state lithium polymer secondary batteries (LPB) are fabricated with a two-electrode-type cell construction of Li|solid-state polymer electrolyte (SPE)|LiFePO4. Plasticizers of poly(ethylene glycol) (PEG)-borate ester (B-PEG) or PEG-aluminate ester (Al-PEG) are added into lithium-conducting SPEs in order to enhance their ionic conductivity, and lithium bis-trifluoromethansulfonimide (LiTFSI) is used as the lithium salt. An improvement of the electrochemical properties is observed upon addition of the plasticizers at an operation temperature of 60,°C. However, a decrease of discharge capacities abruptly follows after tens of stable cycles. To understand the origin of the capacity fading, electrochemical impedance techniques, ex-situ NMR and scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) techniques are adopted. Alternating current (AC) impedance measurements indicate that the decrease of capacity retention in the LPB is related to a severe increase of the interfacial resistance between the SPE and cathode. In addition, the bulk resistance of the SPE film is observed to accompany the capacity decay. Ex situ NMR studies combined with AC impedance measurements reveal a decrease of Li salt concentration in the SPE film after cycling. Ex situ SEM/EDS observations show an increase of concentration of anions on the electrode surface after cycling. Accordingly, the anions may decompose on the cathode surface, which leads to a reduction of the cycle life of the LPB. The present study suggests that a choice of Li salt and an increase of transference number is crucial for the realization of lithium polymer batteries. [source]

Electric-Field Enhancement of Photovoltaic Devices: A Third Reason for the Increase in the Efficiency of Photovoltaic Devices by Carbon Nanotubes

ADVANCED MATERIALS, Issue 20 2010
Wonjoo Lee
Electric-field enhancement of photovoltaic devices by carbon nanotubes (CNTs) is reported as a third alternative for increasing the efficiency of photovoltaic devices. Due to the formation of an efficient electronic energy-cascade structure, the decrease of the interfacial resistance, and the improvement of the electrical field, the power-conversion efficiency of solar cells was increased by 22% in the presence of the SWNTs. [source]

Fabrication of Gas Electrodes by Wet Powder Spraying of Binder-Free Particle Suspensions Using a Pulse Injection Process

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2007
Naoki Oishi
A process for wet powder spraying of binder-free particle suspensions using pulse injection was devised for the fabrication of gas electrodes. The resulting deposited electrodes were found to have fine and uniformly distributed pores, to have good adhesion, and low interfacial resistance on electrolyte substrates. The uniformity of the layers was improved by decreasing the spray pulse to 0.05 s with a 1-s off period. Even without drying or any pre-treatments before firing, there was no cracking or delamination of the deposited layer. The deposited layer remained porous, crack-free, and well bound to the substrate after firing. [source]

Interpreting Impedance Response of Silicon Carbide Whisker/Alumina Composites Through Microstructural Simulation

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2006
David S. Mebane
A three-dimensional, object-defined Monte Carlo simulation is applied to alumina-silicon carbide whisker ceramic matrix composites. The simulation takes whisker orientation and size distributions into account simultaneously, and calculates a connectivity factor that relates whisker conductivity to macroscopic conductivity. Simulation results are compared with electrical measurements taken on real samples via impedance spectroscopy. Results show that the effect of whisker clumping can be seen in the impedance response as a decrease in the overall measured conductivity. Results also show that interfacial resistance influences the overall resistivity strongly relative to connectivity at volume fractions far above the percolation threshold. The possible mechanisms for interfacial resistance in the composite and their effect on the impedance response are discussed. [source]

Determination of the Thermal Resistance of the Polymer,Ceramic Interface of Alumina-Filled Polymer Composites

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2004
Richard F. Hill
To model the thermal conductivity of polymer composites that are filled with ceramic powders, the conductivity of each component as well as the interfacial resistance at each ceramic,polymer boundary must be known. An indirect method to determine this interfacial boundary resistance is proposed by preparing large-scale "macromodel" simulations of the polymer,ceramic interface. Macromodels, prepared by spin-coating a polymer layer onto sapphire wafers, were formed in a sapphire,polymer,sapphire sandwich type structure. The interfacial boundary thermal resistance was calculated from thermal resistance measurements made on the macromodels. [source]

Novel microporous poly(vinylidene fluoride)- graft -poly(tert -butyl acrylate) electrolytes for secondary lithium batteries

POLYMER INTERNATIONAL, Issue 11 2008
M Abdul Kader
Abstract BACKGROUND: Much interest has recently been shown in improving the performance of lithium-ion polymer batteries with gel polymer electrolytes (GPEs) due to a rapid expansion in industrial demand. Novel GPEs based on poly(vinylidene fluoride)- graft -poly(tert -butyl acrylate) (PVDF- g - tBA) microporous mats are suggested in this study. RESULTS: Microfibrous polymer electrolytes were prepared using electrospinning and characterized for extent of grafting, morphology, crystallinity, electrochemical stability, ionic conductivity, interfacial resistance and cell cycleability. The degree of crystallinity was lower for tBA-grafted PVDF mats than that of neat PVDF. The PVDF- g - tBA showed an improvement in the ionic conductivity, electrochemical stability, interfacial resistance and cyclic performance. CONCLUSION: The tBA-grafted PVDF microporous electrolytes are promising candidates for enhancing the performance of lithium-ion polymer batteries. Copyright © 2008 Society of Chemical Industry [source]