Light-emitting electrochemical cells (LECs) based on Ru(bpy)3(ClO4)2 are thin-film solid-state devices that typically operate at low applied voltages and show relatively high efficiencies. They ...suffer, however, from poor operating lifetimes. A proposed source of lifetime degradation is water in the film. Previous studies have revealed a marked difference in operation performance between cells fabricated and tested inside a drybox and those made and tested under ambient conditions. This study further characterized the effect of water vapor on device operation. The role of water as solvent within the thin-film devices was found to increase the current and the initial light output, but at the expense of more rapid decay in light generation.
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IJS, KILJ, NUK, PNG, UL, UM
The barrier properties of a poly(aniline) membrane may be tuned by electrochemical control of the polymer’s oxidation state. We have exploited this behavior to electrochemically modulate the ...permeation of two probe molecules of differing charge through a supported poly(aniline) membrane. The trans-membrane flux was measured for neutrally charged phenol and negatively charged 4-hydroxybezenesulfonate as a function of the polymer oxidation state, which was controlled by stepping the potential applied to a poly(aniline) film from a reducing potential to increasingly more oxidizing values. The fluxes of phenol and of 4-hydroxybezenesulfonate were enhanced when the polymer was poised in the half-oxidized, emeraldine state as compared to that of the reduced, leucoemeraldine state. Additional film oxidation to the pernigraniline state produced an enhanced flux of 4-hydroxybenzenesulfonate over phenol. The flux responses for these probe molecules are explained through a combination of oxidation-induced film swelling and electrostatic effects due to variable film charge. At high membrane potentials, film modulation was disrupted by poly(aniline) hydrolysis and decomposition. This work demonstrates that the permeation of a supported poly(aniline) membrane may be modified electrochemically to produce controllable barrier properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this work, we present a combination of experiments and modeling of a two-layer anode structure designed by EnPower Inc. for high-energy and fast-charge capabilities. The anode consists of lower ...porosity near the current collector and higher porosity near the separator with comparable active materials in both regions. A pseudo-two-dimensional electrochemical–thermal model was designed to represent the performance of this electrode. Simulations, consistent with experiments, show superior ion transport and lithiation in the multi-layer anode (MLA) compared to a conventional single-layer anode (SLA). Surprisingly, this improved transport in MLA manifests as enhanced cathode performance during high-rate discharge and this, in turn, provides higher energy density for MLA. Similarly, during fast charge, less irreversible lithium is deposited due to this improved transport in MLA, and hence MLA exhibits less capacity fade compared to SLA. Polarization analysis demonstrates marginally lower cumulative overpotential for MLA in different case studies; however, MLA cells maintain a significantly higher capacity in the same conditions and have more than double the cycle life. This means despite the apparently limited polarization benefit provided by MLA; the MLA structure can more reliably be employed in cell designs. Additional design changes are also analyzed by means of the model.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
4.
Tech Highlights - Fall 2023 Pile, Donald; Gallaway, Joshua; Schindelholz, Mara ...
The Electrochemical Society interface,
09/2023, Volume:
32, Issue:
3
Journal Article
Open access
A collection of technology highlights pulled from recent papers published in ECS journals.
The thermal abuse tolerance of Li-ion cells depends not only on the stability of the active materials in the anode and cathode but also on the stability of the separator which prevents direct ...interaction between these electrodes. Separator response has been measured as a function of temperature and high voltage both for isolated materials and in full 18650 cells. Separators with different compositions and properties were measured to determine the effect of separator melt integrity on cell response under abusive conditions. These studies were performed as part of the U.S. Department of Energy (DOE) Advanced Technology Development (ATD) Program.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Researchers from the South China Normal Universily described a simple paper-based bipolar electroluminescence (BP-ECL) biosensor. The BPE was formed by screen-printing a U-shaped carbon ink trace ...crossing two regions of a channel formed by wax screen printing. Two carbon driving electrodes were also printed at the same time at the two ends of the channel. Oxidases and luminol were deposited at the anodic pole of the BPE. Under optimized conditions. The paper-based BP-ECL biosensor was successfully used to determine choline, lactate, and cholesterol in human serum.
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