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Bio-Logic AWS-A20 at Biosensing Conference

AWSensors at the 5th International Conference on Biosensing technology

May 4th 2017

AWSensors technology will be at the  5th International Conference on Bio-sensing technology to be held at Riva del Garda, Italy, from May 7th to 10th. We are pleased to invite you to see our biosensing platforms at the booth of Bio-Logic, our OEM distributor.

AWS A20-F20 platform is the most flexible and sensitive QCM-D system in the market. It is able to work with low and high frequency QCM sensors and SAW sensors. It also ensures high sensitivity because of a novel method of characterization that keeps noise at very low level in spite of working at high frequencies by using AWS-HFF sensors (100-150 MHz). AWSensors also provides QCM and SAW sensors and a wide range of cells and accessories to customize experiments and tests according to specific conditions required by scientists.

Therefore, AWS A20 system provides you with big competitive advantages:

–       High flexibility, capable to work with any acoustic wave sensor; modular system capable to be upgraded with more channels after purchase (up to 4)

–       High sensitivity

–       Customization, with accessories to make measurements in specific conditions

–       Price convenience

Do not miss the opportunity to check the advantages of our technology at the booth of Bio-Logic and meet our Application Scientist, Mrs. María García.

Electrochemical and viscoelastic evolution of dodecyl sulfate-doped polypyrrole films during electrochemical cycling

Authors: Wanli Gao, Ozlem Sel, Hubert Perrot

Journal:  Electrochimica Acta (2017)

The correlation between electrochemical and viscoelastic properties of electrodeposited dodecysulfatedoped polypyrrole (PPy-DS) during electrochemical cycling process was described through combining electrochemical quartz-crystal microbalance (EQCM), ac-electrogravimetric characterizations and electroacoustic measurements. as the PPy-DS electrode evolves during the course of consecutive cycling in aqueous NaCI electrolyte, the film exhibits (i) an obvious ion-selective transition from cations to anions in the charge compensation process; (ii) an inferior electrochemical performance accompanied with increased stiffness (increased storaged moduli, G’); and (iii) depleted capability of ionic exchange through film/electrolyte interface. PPy-DS conducting polymer electrodes (CPEs) are of interest in energy storage and the relationship between electrochemical and viscoelastic properties during electrochemical cycling process is essential for promoting the performance of these devices. In this perspective, ac-electrogravimetry combined with electroacoustic measurements can be suggested as an alternative method to synchronously probe the electrochemical and mechanical evolution and has the potential to offer a generalized route to study aging mechanism of CPEs.

 

pH Controlled Electrochemical Deposition of Polyelectrolyte Complex Films

Authors: Kazi Sadman, Qifeng Wang, Shawn H Chen, David Efim Delgado and Kenneth R Shull. Northwestern University, Evanston, Illinois, US

Journal:  Langmuir, American Chemical Society (2017)

Polyelectrolyte complex (PEC) films made from oppositely charged polymer chains have applications as drug delivery vehicles, separation membranes, and biocompatible coatings. Conventional layer-by-layer (LbL) techniques for polyelectrolyte coatings are low-throughput and multistep processes that are quite slow for building films on the order of micrometers. In this work, PEC films are electrochemically deposited using a rapid one-pot method yielding thick (1 μm) films within short experimental time scales (5 min). This rapid electrodeposition is achieved by exploiting the reduction of hydrogen peroxide at mild electrode potentials that avoid water electrolysis, yet trigger the pH responsive self-assembly of a PEC film composed of poly(acrylic) acid and poly (allylamine) HCl. In-situ rheology using an electrochemical quartz crystal microbalance (EQCM) quantified the shear modulus-density product of the deposited layer to be on the order of 107 Pa-g/cm3 at a frequency of 15 MHz, with a viscoelastic phase angle at this frequency of approximately 50. This electrodeposition scheme furthers the development of PEC coatings for more high-throughput applications where a fast and efficient single step approach would be desirable for obtaining coatings.

Why using AWSensors technology in Lithium-Ion Battery Research?

February 9th 2017

AWSensors and the second largest university in Israel, Bar-Ilan University, signed an agreement to collaborate on lithium-ion battery and energy storage research. AWSensors will work with the Group of Electrochemistry, the most important of Israel. It is led by Professor Doron Aurbach, awarded in 2005 by the Electrochemical Society (ECS) for his work on batteries. He will also receive the 2017 Alan J. Bard Award in Electrochemical Science.  The Award is considered one of the greatest honors in electrochemistry.

We talked with Prof. Mikhael Levi, who will lead the Collaboration Agreement,  about why he is interested in using AWSensors technology. Here we present a brief summary about what he told us.

– Could you explain briefly your interest in battery and energy storage research?

The interest stems from the attempt to a deeper understand the mechanism of ions intercalation into battery electrodes. A more simple case relates to electrode behaviors in aqueous solutions because of negligible effect of the parasitic reactions, absence of surface-electrolyte interfaces (SEI), higher conductivity of solutions compared to that in aprotic solvents, etc. A more complicated and practical case relates to Li-battery electrodes in non-aqueous (aprotic) solutions when extremely high potentials of cathodes and extremely low potentials of anodes are reached. At these extreme potentials a strong competition between the intercalation reactions and parasitic processes of decomposition of electrolyte solutions occurs. On the one hand, this makes interpretation of QCM data non-trivial requiring a rigorous control over keeping external conditions constant (temperature, pressure, non-slipping interfaces, bubble gas evolution, etc). On the other hand, QCM-based research can provide reliable information on tracking the mechanical properties of surface-electrolyte interfaces (SEI) which major role is to prevent or at least to reduce the effect of the parasitic reactions. By QCM-based research we understand it beyond the gravimetric method of operation and analysis implying easy access to not only resonant frequency but also to the related motional resistance or other similar damping characteristics such as resonance peak width or dissipation factor.

– Why do you feel that the agreement with AWSensors will benefit your research interest?

I have mentioned that the extreme operating potentials of anodes and cathodes cause numerous difficulties in QCM applications.  We are currently trying to overcome may be the most severe difficulty in adjusting QCM technique for battery electrodes characterization by matching QCM measurement conditions to the conditions used in practical Li-ion batteries. In practical batteries the ratio of active electrode mass to mass of solution is large ensuring suppressed contribution of parasitic reactions, diminishing of self-discharge rate, increasing capacity retention and ensuring good Faradaic efficiency.

QCM measurements relate to flooded cell with the reverse ratio of electrode and electrolyte mass: the mass of the electrode coating used in QCM is limited to low-mass-approximation. On the other hand, the amount of electrolyte in contact with the crystal is high. In principle the amount of electrolyte is limited by the penetration depth (much less then micron).However it is difficult to build the electrochemical cell with such a small separation.

Attempts to increase the loading mass are linked to recording precise shape of the resonance curves on different harmonics to check vertical and spatial heterogeneity of thick coatings, pre-requisite for deciding whether harmonic analysis can be applied to intercalation processes in thick electrodes. We are sure viscoelastic effects are present in thick electrodes already in air and the role of viscoelastic effect increases after contact with liquids.

 

Are you investigating on batteries?

Are you interested in learning more about AWSensors technology?

 

 

Please, CONTACT US for information about the coming workshop on lithium-ion battery research with AWSensors instruments.

Gravimetric and dynamic deconvolution of global EQCM response of carbon nanotube based electrodes by Ac-electrogravimetry

Authors: F. Escobar-Teran, A. Arnau, J.V. García, Y. Jiménez, H. Perrot, O. Sel

Journal: Electrochemistry communications (2016)

The capacity charge storage of carbon nanotube (CNT) based electrodes was investigated by ac-electrogravimetry which couples fast quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS). In contact with an aqueous NaCI electrolyte, evidence was found that there are two types of cations (Na+.H2O and H+) electroadsorbed with different kinetics for cathodic potentials and the Cl– ionsfor anodic potentials together with free water molecules. The reconstruction of the total mass response from independent ac-electrogravimetry measurements agrees perfectly well with the global EQCM response. Our findings reveal the unique sensitivity of the ac-electrogravimetry to provide a fair gravimetric and dynamic deconvolution of the global EQCM responses.

You may read the full paper here