bluuebunny/crossref_metadata_2025 huggingface dataset:
Invited: Utilization of DNA As a Scaffold for Electrode Design for Efficient Bioelectrocatalysis in Fuel Cell Applications
Authors: Minteer Shelley D.
Published: February 2020

DNA nanotechnology is a new field of biology focused on the use of DNA for structural design. Previously, researchers have shown that DNA nanotechnology can be used for immobilizing enzymes. However, DNA is not conductive enough for direct electron transfer between enzyme electrocatalysts and electrode surfaces, so it hasn't been useful for bioelectrocatalytic applications like amperometric biosensors and enzymatic fuel cels. In this talk, we will discuss the use of DNA hydrogels for the preparation of DNA-based redox polymers for both immobilization of oxidoreductase enzymes and mediated bioelectrocatalysis. We will discuss two methods for preparing redox DNA hydrogels including the noncovalent functionalization of DNA with redox molecules via intercalation of aromatic redox probes into the DNA double helix and electrostatic binding of redox-active tetraalkylammonium ions to phosphate groups on DNA. Although these two techniques are used frequently in biomedical applications, this is their first use in the design of electrode structures. These redox DNA hydrogels have demonstrated mediated bioelectrocatalytic glucose oxidation by oxidoreductase enzymes via self-exchange-based mediation. This talk will describe the bio-inspired design of the electrode structures, as well as electrochemical characterization and evaluation of bioelectrodes for sensing and fuel cell applciations.
Photobioelectrochemistry of Intact Chloroplasts for Solar Energy Conversion
Authors: Hasan Kamrul , Milton Ross D , Grattieri Matteo , Minteer Shelley D.
Published: February 2020

Solar energy is a highly exploitable energy source for renewable energy technologies; thus, a great deal of recent research has focused on the ability to generate electrical energy from solar energy (photoelectrochemistry). This has resulted in a wide variety of photoactive biomaterials being studied at electrode surfaces, such as isolated photosystems, thylakoid membranes as well intact photosynthetic organisms.

Chloroplasts are photosynthetic organelles that harness solar energy in higher plants and algae. They are the vital sources of carbon-based fuels and have self-repair mechanisms against photo-damage; however, chloroplasts are less studied for harnessing solar energy. The electrochemical communication of chloroplasts at electrode surfaces is challenging since they are shielded inside thick electrochemically-insulating cell membranes. Therefore, the majority of studies surrounding chloroplasts in photobioelectrochemical systems (PBESs) utilize soluble exogenous electron transfer (ET) mediators. The use of soluble electron mediators, however, is not feasible for large-scale application.

Redox polymers are polymeric backbones that have been modified with redox-active moieties and can be used as an immobilization matrix as well as a non-diffusive electron mediator for extracellular-ET from biomaterials to the electrode. Nevertheless, a successful electrochemical study on chloroplasts with any redox polymer is yet to be reported. Here, we report the photoelectrochemical wiring of chloroplasts on a naphthoquinone-based redox polymer. Intact chloroplasts were immobilized on Toray carbon paper electrodes and illuminated under a fiber optic light to simulate sunlight. Cyclic voltammetric and amperometric experiments demonstrate the ability to obtain photo-excited electrons that are produced from water oxidation by intact chloroplasts. In the presence of a diffusive mediator as well as the redox polymer, maximum photobiocurrents obtained from the chloroplasts are as high as 28±5 µA cm-2.
Equivalent Circuit Modeling of Microbial Fuel Cells Using Impedancespectroscopy
Authors: M Sindhuja
Published: February 2020

The effect of internal resistance on the electrochemical processes of microbial fuel cell is demonstrated by Electrochemical Impedance Spectroscopy. The decrease in solution resistance and increase in charge transfer resistance influenced the performance of microbial fuel cell over time. To understand the effect of the parameters on the electrochemical processes a lumped equivalent circuit model for activated charcoal based microbial fuel cell and the Equivalent circuit fitting model of Nyquist plot for graphite based microbial fuel cell is adopted. The Equivalent circuit models predicted negligible activation polarization for activated charcoal electrode assembly and significant activation polarization for graphiteelectrode assembly. The rationale behind this observation could be due to the higher affinity for biofilm formation on activated charcoal in comparison to graphite. The efficiency of the microbial fuel cell went down with time as the electrochemical kinetics predominates over biochemical kinetics. The Maximum power density and current density measured are (i) 8 mW/m2 and 103 mA/m2 respectively for activated charcoal based microbial fuel cell, (ii) 1015 mW/m2 and 11803.5 mA/m2 respectively for graphite electrodes based microbial fuel cells. The power density is 7.6 times higher than the literature data of 133 mW/m2 for graphite based microbial fuel cells.

Figure 1
Biological Power Sources Based on Transparent and Capacitive Electrodes
Authors: González-Arribas Elena , Aleksejeva Olga , Shleev Sergey
Published: February 2020

Here we present fabrication and characterization of transparent biological power sources, specifically, both conventional and charge-storing bio-fuel and bio-solar cells. The biodevices are built on different transparent conductors – metal and oxide-, viz. gold and indium tin oxide. Transparency is a relevant feature to take into account when developing power sources for certain potential applications. However, most of designed biological power sources described in the literature are opaque.

Bio-fuel cells are suitable power sources to implement in electronic contact lenses. The power needed for smart lenses is generated by converting in situ available chemical energy from different biofuels presented in human tears into electric energy. Here we show different approaches that our group has developed to design high performing and transparent conventional enzymatic fuel cells [1] and self-charging chemical biosupercapacitors [2, 3] for contact lens application (Fig. 1A).

Bio-solar cells, i.e. devices based on biocatalysts, which can directly transform solar energy into electric energy, are in the spotlight nowadays. Here we show the very first solar biosupercapacitor (Fig. 1B), which is built from transparent and nanostructured, i.e. highly capacitive, indium tin oxide based electrodes [4]. The biodevice is able to convert solar energy into electric energy, which is capacitively stored within the same volume used for conversion. The solar biosupercapacitor, consisting of thylakoid membrane modified anode and bilirubin oxidase modified cathode ionically coupled in a closed system at neutral pH, is charged by the ambient daylight. Because of the materials used, the resulting biodevice is a simple to build, inexpensive, and sustainable power source for low-power low-voltage electronics.

Fig. 1. Transparent biological power sources.

(A) Charge-storing glucose/oxygen fuel cell. (B) Self-charging solar biosupercapacitor.

This work has been financially supported by the European Commission (PEOPLE-2013-ITN-607793).

1. D. Pankratov, R. Sundberg, J. Sotres, I. Maximov, M. Graczyk, D.B. Suyatin, E. González-Arribas, A. Lipkin, L. Montelius, S. Shleev, Journal of Power Sources, 2015, 294, 501.

2. D. Pankratov, E. González-Arribas, Z. Blum, S. Shleev, Electroanalysis, 2016, 28, 1250.

3. E. González-Arribas, D. Pankratov, G. Sébastien, N. Mano, Z. Blum, S. Shleev, Electroanalysis, 2016, 28, 1290.

4. E. González-Arribas, O. Aleksejeva, T. Bobrowski, M.D. Toscano, L. Gorton, W. Schuhmann, S. Shleev, Electrochemistry Communications, 2017, 74, 9.

Figure 1
Nanocrystalline Co3-XNixO4 with Low Ni Concentration: Enhanced Oxygen Evolution Activity Compared to Co3O4
Authors: Singhal Aditi , Bisth Anuj
Published: February 2020

Nano-crystalline Co3O4 and a series of Ni-doped Co3O4; Co3-xNixO4 (0.0075 £ x £ 0.30) have been synthesized using solution combustion method. Complete characterization is carried out using XRD, TEM and BET surface area analysis. XRD shows pure nano-crystalline phase of Co3O4 with no peaks related to Ni or nickel oxide confirming that Ni is not present as a separated phase on the surface and has been substituted in the lattice. TEM studies for as prepared samples (400 oC) show that particles of 0.5% Ni doped Co3O4 (Co2.985Ni0.015O4) are around 60 nm in size. Calcination of Co2.985Ni0.015O4 at 600 °C for 10 hours results into well-defined hexagonal morphology which could be seen both by TEM and SEM. After calcination, particle size becomes 70 nm. Estimated BET surface area for Co2.985Ni0.015O4 (calcined at 600°C) is 10m2/g.

Detailed electrochemical studies have been carried out in basic, neutral buffer and neutral electrolyte medium. Both Co3O4 and Co3-xNixO4 were found active for oxygen evolution reaction (OER) with an interesting behavior in doped compound. It is found that lower nickel doping significantly enhances the OER activity in all the mediums; basic, neutral and neutral buffer. Figure 1 depicts that just 0.5% Ni-doped Co3O4 (Co2.985Ni0.015O4) is far more active than Co3O4 both in terms of current density and onset potential in K2SO4 medium. This enhancement nevertheless decreases once the doping concentration reaches beyond 0.5%. Figure 2 shows that OER activity (chronoamperomertic current) of Co3O4 increases after 0.25% Ni doping peaking at 0.5% and thereafter the reduction in the activity takes place. 1% Ni doped Co3O4 is less active than 0.25% Ni doped Co3O4. Once the doping concentration is 2.5% there is no enhancement in the activity compared to Co3O4. In the same way no effect is seen at 5 and 10% doping of Ni and the activity is similar to parent Co3O4. Same trend is observed in all other medium. Interestingly, in phosphate buffer solution (PBS) Co3O4 and 0.5% Ni-doped Co3O4 show OER at near thermodynamic potential i.e at a very low over potential. Similar effect was observed by Nocera and co-workers on cobalt oxide 1-2. This conclusively states that Co3O4 and its doped variant form similar type of in situ active sites as noticed Nocera and co-workers.

References : 1. M.W. Kanan, D.G. Nocera, Science 321 (2008) 1072-1075. 2. Y. Surendranath, M.W. Kanan, D.G. Nocera, Journal of the American Chemical Society 132 (2010) 16501-16509

Figure 1
(Invited) Evidence for Magnetic Effects on Electron Transfer
Authors: Lee Heung Chan , Gellett Wayne L. , Minteer Shelley D. , Knoche Krysti L. , Rathuwadu Nadeesha , Leddy Johna
Published: February 2020

Electron transfer events are commonly considered in light of the transfer of charge. But, electrons also have properties of spin. Here, various systems are evaluated for impact of spin on rates of electron transfer. Literature and experimental data are considered. Electron spins interact with magnetic fields. In our experimental studies, magnetic microparticles are introduced to the electrode surface.

From the literature, correlations between measured parameters and magnetic properties of electrodes and electroactive species are presented. This includes rate constants for heterogeneous and homogeneous electron transfer.

From laboratory studies with micromagnets held to the electrode with a Nafion coating, impacts on homogeneous and heterogeneous electron transfer are found.

For transition metal complexes such as M(bpy)₃z+ present at near contact in Nafion, electron hopping rates are measured as self exchange rates, k₁₁. When compared to simple Nafion films, rates of electron electron hopping are enhanced in the presence of magnets; effects scale with the number of spin (unpaired electrons) involved in the reaction. Temperature studies chart variation in the energy of activation (reorganization energy) and the pre-exponential factor.

For adsorbate reactions, magnetic effects are substantial for reactions such as CO oxidation and hydride formation on palladium. Rates are enhanced > 100 fold.

Hydrogen evolution reaction (HER) rates for poorly electrocatalytic electrodes are enhanced substantially on introduction of micromagnets.

Because transfer of electrons requires transfer of both charge and spin, electron transfer rates can be slowed when rates of spin transfer are slow. Facilitating rates of spin transfer as by introduction of micromagnets increases rates of electron transfer reactions.
(Invited) Impact of Carbon Surface Functionalities on the Electrochemical Detection of Hemoglobin
Authors: Andreas Heather Anne , Tom Justin
Published: February 2020

The electrochemical biosensing of hemoglobin (Hb) may provide a relatively fast method of detection with the possibility of developing point-of-care diagnostics or at-home monitoring; however, obtaining a Hb electrochemical signal is often slow and difficult because the four redox active heme groups are buried in the interior hydrophobic regions of the protein. Ideally, the biosensor electrode would be inexpensive and formed from environmentally sustainable materials, such as carbon. However, the electroactivity of Hb is inconsistent on different carbon electrode materials. Additionally, Hb electroactivity is strongly dependent on whether the Hb is immobilized on the electrode surface or is in a solution-based sample. Clearly, for a point-of-care diagnostic, it would be useful to be able to measure the Hb concentrations within a liquid phase, and therefore a carbon material which evidences Hb-electroactivity is required.

Until this work, there was little understanding of the role that carbon-oxygen surface functional groups (from the carbon electrode) played in Hb electroactivity. We examine Hb electroactivity of several carbons are examined through cyclic voltammetry and differential pulse voltammetry in a neutral phosphate buffered electrolyte. Carbon-oxygen surface functionalities were characterized using X-ray photoelectron spectroscopy (XPS), thermal programmed desorption (TPD) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR).

Our findings show that Hb electroactivity is inhibited by ether and carbonyl surface groups present on the carbon electrode. Using this information, a Hb-inactive carbon (Vulcan XC-72) was made active for Hb detection by removal of these surface groups (see figure). Ultrasonication removed the ether functionalities, resulting in a significant increase in the Hb electroreduction. The amount of reduction was increased further if the ultrasonication was followed by a relatively simple 15 minute electroreduction at -1.95 V vs. Hg/Hg2SO4 (saturated K2SO4) in stirred 10 mM phosphate electrolyte (pH 5.03) purged with N2. The electroreduction was shown to selectively remove the carbonyl and quinone functionalities, resulting in the increase Hb electroactivity.

The knowledge of carbon-oxygen surface functionalities is essential to better understand hemoglobin’s electroactivity on carbon and influences the choice of carbon electrode materials for further development of hemoglobin electrochemical biosensors.

Figure: Representative CVs (a) and DPVs (b) of glassy carbon (dotted green curve), ultrasonicated Vulcan XC-72 on glassy carbon (dashed purple curve) and ultrasonication+electrochemically reduced Vulcan XC-72 on glassy carbon (solid purple curve) in 0.1 M PB containing 0.2 g L-1 BHb from at least three replicate trials.

Figure 1
(Invited) Polyoxometalate Modified Biomass Carbon for Supercapacitor Electrodes
Authors: Genovese Matthew , Lian Keryn
Published: February 2020

Biomass waste carbon materials have been emerging as high performance and low cost electrodes for energy storage such as supercapacitors. Addition of thin layers of redox active pseudocapacitive materials onto biomass activated carbon can leverage the strength of the electrochemical activity of the former and the high surface area as well as the low cost of the latter. In our study, several biomass carbon materials, including corncobs and pine cones, have been investigated as substrates for adsorption of electrochemically active and highly reversible polyoxometalates (POM) clusters. In this talk we will compare these two carbons to show the influential factors on the adsorption of POM clusters.

Among various chemical and structural properties of biomass activated carbons, we have found that POM adsorption is highly favored within a carbon matrix possessing pore diameters in the 1-2 nm range. These large micropores are big enough to accommodate the large POM cluster, while still being small enough to effectively trap and hold the molecule. Pine cone activated carbon with this optimal pore arrangement demonstrated ultra-high loading of the PMo12O40
3- (PMo12) molecule resulting in carbon-POM hybrid materials consisting of over 55 wt. % PMo12. This large POM loading imparted tremendous redox activity to the already high double layer capacity of the carbon substrate, leading to a high areal capacitance of 1.19 F cm-2 for the hybrid material, close to 2.5 times larger than for unmodified carbon. We have also demonstrated that a mixed molecular coating combining multiple POM chemistries can be adsorbed onto the activated carbon substrate to create a more ideally capacitive charge storage profile. These results demonstrate a promising method for the design of high performance yet cost effective hybrid energy storage electrodes.
The Improvement of Boron-Doped Diamond Anode System in Electrochemical Oxidation and Fenton Coupling System Degradation of p-Nitrophenol By Sensing Electrode of Iron
Authors: Xing Xuan
Published: February 2020

Boron-doped diamond (BDD) electrodes are promising anode materials in electrochemical oxidation system in degradation of wastewater containing toxic and bio-refractory organic pollutants due to their corrosion resistant ability and strong oxidation ability. In order to further improve the performance of BDD anode system, electrochemical oxidation of p-nitrophenol(PNP) was initially investigated in BDD anode system with the presence of sensing electrode. The results showed that the performance of the synthetic system was improved under neutral conditions with the joint actions of anode oxidation (64.6%) and H2O2 which was produced by oxygen reduction at carbon fiber cathode (11.9%). Under acid conditions, the degradation efficiency of PNP was further improved from 41.8% of the traditional system to 84.5% of the synthetic system. The strong oxidation ability was due to the anode oxidation (24.5%) and Fenton reaction by H2O2 and Fe2+ releasing from sensing electrode (66.7%). Moreover, under alkaline conditions, the results showed that the combined system was also improved by the coagulation of iron flocs formed from sensing electrode besides anode oxidation. Furthermore, hydroxyl radicals and H2O2  which were dominated oxidants were detected and quantified for the oxidation mechanism explanation.
Electrochemical Kinetics and Dimensional Considerations at the Nanoscale
Authors: Yamada Hidenori , Bandaru Prabhakar R
Published: February 2020

A critical understanding of thermodynamics inherent to charge transfer is necessary for scientific insights, as well as for applications ranging from biochemical reactions, electrocatalysis, and charge storage in capacitors and batteries. In this letter, we first examine issues related to conventional classical reaction rate theories, such as the Marcus-Hush models for homogeneous electron transfer, and the extensions by Chidsey to heterogeneous electron kinetics. While the foundational attributes have almost always been reckoned in terms of one-electron based charge transfer, much of the theoretical and experimental analysis has only obliquely referred to dimensionality considerations.

We have found a major role of the dimensionality dependent density of states (DOS) in mesoscale and nanoscale materials in modulating electron kinetics. We have then discovered several novel characteristics that have never been reported before, such as, (i) the observation of DOS dependent reaction rate constant and electrical current oscillations, coupled with (ii) the prediction of tests of dimensionality/quasi-dimensionality. We posit a chirality dependent electron transfer rate constant in nanotubes and graphene-like structures, considering the coupling of the energy level spacing in the nanostructured electrode with that in the ambient, e.g., electrolyte. The manifestation of novel features in electron transfer kinetics as a function of dimensionality probes new frontiers in the tunability of electrochemical characteristics. We expect our work to generate very wide interest in the scientific community due to the importance of heterogeneous charge transfer across a variety of disciplines.
Effects of Electrolyte Composition on AC-Driven Electrochemiluminescence from Anthracene Derivatives Having Blue Emission
Authors: Tsuneyasu Shota , Ichikawa Takuya , Nakamura Kazuki , Kobayashi Norihisa
Published: February 2020

Electrochemiluminescence (ECL) is a light emitting phenomenon of excited species which is generated from electrochemical reaction at electrodes. ECL reaction has attracted great interest to utilize as the novel kinds of light emitting devices. We have reported that the ECL device can be integrated with reflective displaying devices based on liquid crystal[1] or organic electrochromic[2] technologies. Moreover, the ECL emission colors from the ECL electrolyte solution dissolving 9, 10-diphenylanthracene (DPA) and rubrene in N-methyl-2-pirroridone (NMP) can be controlled by changing the frequency of alternating current (AC) voltage.[3]

Here, we focused on the blue emission of AC-driven ECL (AC-ECL) systems because the ECL intensity and long-term stability were unsatisfactory in present stage. One of the reasons for the issue is that the balance of redox species in the device did not exactly match. In this study, we introduced mixed solvent of propylene carbonate (PC)-toluene system (volume ratio = 1:1) for achieving the stable blue ECL from DPA molecule. PC is well known as the electrochemically stable solvent; toluene can also dissolve the large amount of aromatic compound such as DPA. We measured the electrochemical and optical properties of the DPA in NMP or PC/toluene electrolyte solution in order to discuss the effect of stabilities of redox species on the AC-ECL properties. As a result, it was found that the composition of electrolyte affected the stability of oxidized and reduced species. Moreover, the emission properties of the AC-ECL device were strongly depended on the stability of redox species. From these results, to achieve the good performance of the blue ECL device, it is required that the exactly matched balance of redox species in the device.

Reference

[1] S. Tsuneyasu, K. Nakamura, N. Kobayashi, Chem. Lett., 45, 949 (2016).

[2] S. Tsuneyasu, L. Jin, K. Nakamura, N. Kobayashi, Jpn. J. Appl. Phys., 55, 041601 (2016).

[3] T. Nobeshima, M. Nakakomi, K. Nakamura, N. Kobayashi, Adv. Optical Mater., 1, 144 (2013).
Electrodeposition with Nanoparticles As Nano-Bioplar Electrodes
Authors: Crouch Garrison , Han Donghoon , Fullerton Susan , Go David B. , Bohn Paul W.
Published: February 2020

Bipolar electrochemistry has been used in examination of electrochemical effects under high electric fields, optically-coupled experiments, and geometries where conventionally-connected electrodes would be prohibitively complex. In macro-scale bipolar electrochemistry, the difference in electric potential between the electrode and the surrounding electrolyte provides the driving force for a chemical reaction. This research extends on previous work by examining the kinetics and underlying mechanistic behavior of nanoscale bipolar electrodeposition to create conductive filaments, which behave differently due to inherent limitations of nanoscale mass transport. Nanoscale conductive filaments, usually associated with resistive memory or memristor technology, may also be used for chemical sensing and in the creation of nano-patterned electro-optic or electronic materials. Realistic implementation of the technology requires precise knowledge of the conditions that control the formation and dissolution of filaments. A silver (Ag) conductive filament is created by electrodeposition in a nanoscale gap between two electrodes, creating an atomic-scale junction. In this work, Ag conductive filaments are formed through a polymer electrolyte using a conductive atomic force microscope (C-AFM). Statistical analysis shows that the distribution of formation times exhibits Gaussian behavior, which can be modified by changing electrical parameters, polymer electrolyte thickness, and surface functionalization. Further, Ag nanoparticles have been embedded into the polymer electrolyte film, to serve as nanoscale bipolar electrodes, and statistical analysis suggests that bipolar electrochemical processes at the Ag nanoparticles slows filament formation compared to polymer films without nanoparticles. Dissolution time distributions are lognormal, and repeated re-formation of filaments from previously formed structures is characterized by rapid re-growth. The experiments demonstrate a direct-write bipolar electrochemical deposition/dissolution strategy developed as an approach to reconfigurable, non-contact in situ wiring of nanoparticle arrays – thereby enabling applications where actively-controlled connectivity of nanoparticle arrays is used to manipulate nanoelectronic and nanophotonic behavior. With application areas ranging from massively-parallel chemical sensing arrays to non-contact tunable metamaterials, increasing the repeatability and mechanistic understanding of bipolar nanoelectrodeposition is important to advancing the use of similar technology in real-world devices.

This work was supported by a NASA Space Technology Research Fellowship NNX16AM45H and the Defense Advanced Research Projects Agency FA8650-15-C-7546.
(Invited) Robust Internal Temperature Sensing of Large-Format Li-Ion Cells
Authors: Zhang Guangsheng , Ge Shanhai , Leng Yongjun , Yang Xiao-Guang , Marple Dan , Wang Chao-Yang
Published: February 2020

Large temperature difference arises in big-size Li-ion cells (e.g. 94Ah Samsung cells) due to low thermal conductivity of battery materials, especially under extreme conditions like high C rate operation at low temperatures or abuse conditions [1]. Previous research [2,3] has attempted to embed micro thermocouples in 18650-format cylindrical cells (1.6 Ah) and demonstrated that internal temperature sensing is more useful than surface temperature sensing in early detection of abnormal thermal behaviors for safety enhancement. For practical applications of this technique, internal temperature sensors must be robust and durable to survive battery life cycle and must be low cost. In this study we developed a new resistance temperature device (RTD) based on nickel foil that meets both criteria. Embedded in 10Ah pouch cells, these in-cell temperature sensors still function well after the cells experienced 2,500 cycles. It is believed that low-cost, durable and reliable in-cell temperature sensors have finally arrived to enable substantial improvement in the Li-ion battery’s high-temperature safety and thermal management.

References:

X.G. Yang, T. Liu and C.Y. Wang, Innovative heating of large-size automotive Li-ion cells, Journal of Power Sources, accepted for publication, 2017.

G.S. Zhang, L. Cao, S. Ge, C.Y. Wang, C. E. Shaffer and C. D. Rahn. In situ measurement of radial temperature distributions in cylindrical Li-ion cells, Journal of The Electrochemical Society, 2014, 161: A1499-A1507

G.S. Zhang, L. Cao, S. Ge, C. Y. Wang, C. E. Shaffer and C. D. Rahn. Reaction temperature sensing (RTS)-based control for Li-ion battery safety, Scientific Reports, 2015, 5: 18237
Solid Electrolyte Interphase Formation and Failure Mechanisms in Lithium–Ion Batteries: In-Situ AFM Imaging
Authors: Huang Zhuangqun , Kumar Ravi , Yermolenko Ivan , De Wolf Peter , Xiao Xingcheng , Sheldon Brian W.
Published: February 2020

The lifetime and performance of lithium-ion batteries depend significantly on the formation and evolution of the solid electrolyte interphase (SEI) layer. Si has almost 10 times theoretical specific capacity compared to current state-of-the-art graphite anode materials in Li-ion batteries, which is highly attractive for electric vehicle applications. However, this energy advantage comes with a ~300% volume change during voltage cycling, which causes substantial deformations to SEI. The mechanical integrity of SEI on Si electrodes is highly important in developing commercial Si-based batteries. For R&D, directly probing the SEI evolution is challenging due to 1) SEI thickness is from 10 to 100s of nm; 2) SEI is fragile, which requires a gentle probing force; 3) in situ and operando measurements in electrolyte and under ambient control are needed; 4) multimodal information to clarify the convoluted topographical, mechanical, electrical and electrochemical properties is desired; and 5) a well-defined specimen configuration is needed to interpret the deformation. We have addressed these issues by applying controlled strains to the SEI layer using patterned Si island electrodes and by monitoring these electrodes during voltage cycling on a PeakForce electrochemical AFM system housed inside an Ar-filled glove box (< 1ppm O2 and H2O contents). From this study, we verified that 1) SEI crack formation occured during lithiation, which has been predicted but not directly observed previously; 2) additional SEI formation at low potentials did not fill these cracks, which directly contradicts some prior speculation; 3) SEI had a layered structure, the individual layer of which could be differentiated by the quantitative nanomechanical probing. We are also using Scanning electrochemical microscopy (SECM) to detect local electrochemical differences at stable and unstable SEI sites. Our comprehensive studies not only provide a new in-depth understanding of the in
operando SEI formation, evolution and its mechanical response, but also offer guidance to tailor passivation layers for optimal battery performance.

Figure 1.(A)-(D) AFM images of surface topographic evolution of the SEI layer during lithiation-dethiation cycles. (E) SEM image of a PeakForce SECM nanoelectrode probe. The probe is fully insulated with only the Pt-coated tip apex exposed.

Reference:

[1] Tokranov et al.,
ACS Appl. Mater. Interfaces, 2014, 6, 6672

[2] Tokranov et al., Adv. Energy Mater., 2016, 6, 1502302

[3] Kumar et al., ACS Energy Lett., 2016, 1, 689

Figure 1
(Invited) Characterizing Battery Safety on Aged Cells
Authors: Santhanagopalan Shriram , Cao Lei , Hartig Julia , Wu Zenan
Published: February 2020

Thermal management is a critical component of battery safety. Extensive amount of research has been done on the thermal aspects of battery safety,electrochemical stability of the cell components, initiation of internal electrical failure due to short-circuits, inadvertent inclusion of impurities during the fabrication process, and swelling of cells due to chemical reactions. However, limited results have been reported on how the safety of lithium ion cells changes with aging of the cells. The lowering of capacity as the cell ages may contribute to marginal improvements to the abuse performance of the cells; whereas the increase in resistance and changes to the mechanical and thermal stability window of the components result in narrower windows for safe operation.

In this talk, we present some results on how the thermal, electrical and mechanical properties of lithium ion cells change under different cycling conditions. The testing on the components was performed after careful disassembly of large format (40 Ah) lithium ion cells. Thermal conductivities were measured using the xenon nanoflash technique. Compression and tensile tests were performed on cell components harvested from the cells before and after cycling. Electrochemical resistance build up was characterized using impedance spectroscopy. Cycling conditions included different depth of discharge windows, cycling temperatures as well as charge/discharge rates. Initial results (Fig. 1) show that for the cells tested, under the cycling conditions we used, the anode undergoes a significant amount of degradation in terms of thermal and mechanical properties. The subsequent build up of electrochemical resistance and over heating of the cells lead to lowering of the safety threshold.

We then proceed to integrate the properties of cell components that were experimentally measured, into mathematical models that are used to assess cell-level performance under abuse. The models are used to perform several what-if analyses to identify safety thresholds for the individual cell components for our cell design. We conclude with case studies illustrating how safety thresholds for each cell component is different, how the different factors interact with each other to determine the outcome of cell-level safety, and how to best incorporate these findings to design safer lithium ion cells.

Figure 1
Conductive PEDOT:PSS Electrodes in Electrochromic Devices
Authors: De Keersmaecker Michel , Lang Augustus , Ӧsterholm Anna , Reynolds John R
Published: February 2020

We present new electrochemical device designs made entirely of electrically conducting polymer electrodes to reversibly switch a magenta colored poly(3,4-propylenedioxy-thiophene) (PProDOT) electrochromic polymer (ECP) film. Thin conductive PEDOT:PSS films have been incorporated as conductive transparent electrodes in solution processable absorptive/transmissive (window type) electrochromic devices making it available for high-throughput processing on a wide range of substrates. Different (in)organic acid and polar solvent post-treatments have been used to tune the conductivity of the blade coated PEDOT:PSS electrodes. We reached a conductivity up to 2000 S cm-1 on different substrates, enough to reversibly switch our ECP film between -1 V and 1 V. We will demonstrate how the structural design, construction, charge-balancing, electrode conductivity and the electrochemical properties of the PProDOT have an influence on the device performance quantified by its contrast, switching speed, bending capabilities and long-term switching stability. We combine our device design with a fundamental study of the electrochemical processes occurring at both electrodes. Using these new designs, we have developed an all-polymer solution processed electrochromic device approaching the characteristics of a device made using inorganic transparent conducting electrodes, e.g. indium tin oxide (ITO), with the added advantage of using flexible and rough substrates.

Figure 1
Electrochemical Detection of Sulfanilamide at MWCNT Coated Conducting Polymer Modified Electrode
Authors: Khan Shirinaz , Chillawar Rakesh , Digal Pradesh , Motghare Ramani V
Published: February 2020

Oxidation of sulfanilamide (SN) at the Glassy Carbon Electrode (GCE) modified with a thin layer of electropolymerized Eriochrome Black-T (EBT) and multi walled carbon nanotubes (MWCNT) was investigated voltammetrically. The performance of layer by layer modified composite electrode was compared with bare GCE, p(EBT)/GCE, and MWCNT/GCE using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). An enhanced current response and lower peak potential were observed for SN oxidation at the layered composite electrode compared to rest of the electrodes. Hence, it was employed for analytical determination of SN after optimization of experimental parameters. Under optimized condition, the oxidation peak current increased linearly with concentration of SN over the range of 2 Χ10-8 to 5 Χ 10-6 M. The limit of detection was calculated to be 1.2 Χ 10-8 M. The electrode showed good selectivity, repeatability and reproducibility. It was also successfully applied for the determination of SN present in spiked human serum and ground water samples.

Figure 1
Insight into Understanding Factors Influencing Thermal Oxidation of Iridium Oxide Electrode
Authors: Huang Feifei -F. , Wan Zhengwei , Jin Ying , Wen Lei
Published: February 2020

Researches about thermal oxidation of IrOx electrode for referring are not sufficient. In this study, IrOx pH electrodes fabricated under different temperature and heating time were investigated in detail. The E-pH response, response rate, long-term stability of the IrOx electrodes developed with temperature of 700, 750, 800, 870 ℃ and heating time of 0.5, 1, 1.5, 2 h were detected, respectively. And then, the corresponding characterizations of the fabricated electrodes were examined intensively, which including surface morphology, section morphology & energy dispersive spectrum (EDS) analysis, and electrochemical impedance spectroscopy (EIS). All the electrodes prepared by thermal oxidation had good linear near Nernst response, especially when the temperature was 750℃, 800℃ and 870℃ and the heating time was 1.0h and 1.5h. The IrOx pH electrodes fabricated by the above heat treatment parameters had relatively fast response speed, lesser potential drift, the lower cracks on the surface oxide film, thicker film, smaller film resistance and reaction impedance. Finally, the properties of the electrodes and its relevance with preparation technical parameters and electrode’s structure and composition were discussed.
Design and Fabrication of a Folding- and Dynamics-Based Electrochemical DNA Sensor on Indium Tin Oxide
Authors: Hipp Kenneth Neal , Olson Andrew , Zaitouna Anita J. , Dussault Patrick H. , Lai Rebecca Y.
Published: February 2020

The folding- and dynamics-based electrochemical biosensing platform has proven to be a very versatile sensing platform; it has been employed for detection of a wide range of analytes such as nucleic acids, small molecules, and proteins. One of the most well-studied sensors is the stem-loop electrochemical DNA (E-DNA) sensor. Traditionally, this sensor is fabricated via direct immobilization of thiolated DNA probes modified with a redox label such as methylene blue (MB) onto a polycrystalline gold electrode. Hybridization between the probe and target DNA leads to a change in both probe conformation and flexibility, altering the electron transfer kinetics between MB and the electrode, resulting in a large decrease in the MB current. Although polycrystalline gold is one of the most commonly used electrodes for this class of sensors, there are advantages in investigating alternative electrode substrates. In this study, we have for the first time demonstrated the fabrication of an E-DNA sensor on an indium tin oxide (ITO) electrode. We employed a new phosphonate self-assembled monolayer and potential-assisted “click” chemistry to attach the stem-loop DNA probes onto the ITO electrode. Despite the difference in the probe coverage, the E-DNA sensor fabricated using this approach was found to possess similar qualities as the sensor fabricated on a gold electrode. This sensor fabrication approach is versatile and can potentially be used with other sensors of this class, including the electrochemical aptamer-based and peptide-based sensors.
Electrochemical Biosensors Using Multi-Enzyme Cascade Reactions
Authors: Ramasamy Ramaraja P. , Fang Yi
Published: February 2020

In this work, we demonstrate the development of reliable biosensing methods using multi-enzyme cascade reactions. The cascade reactions result in the generation of an amperometric signal that could be attributed to the selective interaction of the analyte with the enzyme biosensing platform. An example of such a multi-enzyme cascade based amperometric biosensor is an enzymatic methyl salicylate biosensor. Methyl salicylate is an important chemical marker for biotic stress in plants. Here we report the detection of methyl salicylate by three different methods. First two methods involve two enzyme cascade reactions for indirect detection of methyl salicylate through alcohol oxidase/horse radish peroxidase enzyme couple or salicylate hydroxylase/tyrosinase enzyme couple. The third method involves the use of 3 enzyme system that additionally includes an esterase for direct hydrolysis of methyl salicylate for subsequent reactions. The presentation will discuss the mechanisms behind the amperometric detection in each of the above biosensing methods
Fabrication of Porous Current Collectors for Li Ion Capacitor with Pico-Second Pulse Laser and Acceleration of Li+ Ion Pre-Doping Reaction to Laminated Graphite/Porous Current Collector Anodes
Authors: Tsuda Takashi , Ando Fuma , Mochizuki Yasumasa , Gunji Takao , Tanabe Toyokazu , Kaneko Shingo , Ohsaka Takeo , Itagaki Kaoru , Soma Naohiko , Matsumoto Futoshi
Published: February 2020

The fabrication process of porous copper (Cu) current collectors having the pore diameter (3-50 mm) and the rate of opening area (1-4 %) was developed with a system constructed with a pico-second pulse laser and a polygon mirror. The fabricated porous Cu current collectors (Fig. 1) were used to evaluate the porous design on the Cu current collector for exhibiting higher Li+ doping reaction rate with cells in which graphite electrodes were laminated with separators and the laminated graphite anode opposites to Li metal through a separator (Fig. 2). It was found in this study that the conditions of hole diameter (5 mm) and the rate of opening area (1%) is the best one to realize high Li+ doping rate and that the rate determining step of the pre-doping reaction is the diffusion of Li+ion in the pore of the Cu porous current collectors.

Fig. 1 Surface SEM images of prepared porous Cu current collectors. Magnified SEM image of a pore: (A) a view from the plane of incidence of a laser, (B) a view from the plane of emission of a laser. Opening rate of pore on the current collectors: (C) 1 and (D) 2.5 %. The pore size is a constant of 20 mm in all SEM images.

Fig. 2 Schematic description of a cell for pre-doping reaction with graphite layer/porous current collector anodes and a Li metal.

Figure 1
Controllable Synthesis of Tellurium Nanowires for Stretchable and Wearable Piezoelectric Device
Authors: Wang Yixiu , Wu Wenzhuo
Published: February 2020

In the past two decades, various solution-based strategies have been developed by many groups to synthesize Te nanowire, including microwave-assisted process, electrochemical routes, etc. Among these methods, direct chemical reduction has been the most popular due to the considerably high yield and simple procedures, makes it promising method for large-scale production. However, a rational design for the shape and dimension control for the function devices is needed. Here, we report a systematic synthesis of high disperse and single crystal Te nanowire with controllable dimension. Besides, after assembling the tellurium nanowires on the stretchable substrates, a stretchable, soft piezoelectric nanogenerator has been developed with the capability to efficiently convert mechanical stimuli into electric power. We revealed the correlation between the piezoelectric outputs from the integrated devices and the diameters of as-produced tellurium nanowires, which establish process-structure-property-performance relationship in the piezoelectric nanogenerator that may pave way for the nanomanufacturing and practical application of piezoelectric nanomaterials.
Transition Metal Oxide-Based Conversion Reaction for High-Capacity Lithium-Ion Batteries
Authors: Cha Eunho , Choi Wonbong
Published: February 2020

The increasing demand for high efficiency large-scale energy storage applications (e.g. electric vehicles) has led to an expansion in new developmental efforts for high energy-density lithium-ion batteries. However, commercial graphite anodes based on conventional intercalation reaction (involving insertion or extraction of Li ions into or from a layer-type crystal structure) have been faced with a low theoretical specific capacity which prevents them from being applied in advanced energy storages. Transition metal oxide-based conversion reaction (2yLi++ MxOy ↔ xM + yLi2O) could be a novel approach to resolve the aforementioned issues. Here, a facile method is used where layers of nickel oxide (NiO) were formed on 3D Ni substrate via thermal oxidation; subsequently, graphene layers were directly grown on the 3D NiO-Ni structure. Within this structure, porous 3D Ni substrate offers high surface area to form a large loading amount of NiO; also, graphene layers provide structural buffer against volume variations during cycling. Thus, enhanced electrochemical performance is achieved by extending the cycle life and by improving the areal capacity of LIB. The 3D graphene-NiO-Ni structure delivered around 28 mg cm-2 areal density and exhibited an areal capacity of 1.2 mAh cm-2 at 0.1 mA cm-2. The excellent properties and a novel design of the 3D graphene-NiO-Ni anode will contribute to the development of large-scale lithium ion batteris.
Electrochemical Nucleation and Growth of Binary Antimony Telluride Compounds
Authors: Sides William D. , Huang Qiang
Published: February 2020

Whereas antimony telluride based compound materials have been demonstrated to be suitable for phase change memory devices,[1] among other applications, and are well suited to be fabricated via an electrochemical route, the ability to electrodeposit high quality thin films of these materials requires a good understanding of the nucleation and growth behavior that defines the initial stages of growth of these films.[2-4] Although electrochemical nucleation has been studied for decades,[5] little attention has been paid to the behavior of codeposition systems, where two or more materials are deposited simultaneously from a single electrolyte bath. In this study, the nucleation of Sb-Te compound is studied on gold and glassy carbon electrodes, to determine how the nucleation behavior of each element contributes to that of the overall system. Additionally, the effect of applied potential and electrolyte concentrations on the nucleation behavior and deposit composition is studied.

Cyclic voltammetry coupled with quartz crystal microbalance measurements are used to extensively study the deposition processes that occur during compound electrodeposition. It is seen that deposited Te is further reduced to a soluble species near the potentials required to deposit Sb, however the presence of Sb in the deposited film seems to hinder the further reduction to a soluble species, enabling compound film growth (figure 1). Additionally, the free energy released by compound formation allows the compound to be formed at potentials positive to those normally required for Sb deposition. Chronoamperometry, along with TEM-EDS analysis of the composition gradient of individual nucleation sites will be presented and discussed in conjunction with the CVs to understand the nucleation and growth of binary Sb-Te compounds.

REFERENCES

1. Raoux, S.; Wuttig, M., Phase Change Materials: Science and Applications. New York : Springer Dec. 2008: 2008.

2. Huang, Q.; Kellock, A. J.; Raoux, S., Electrodeposition of SbTe Phase-Change Alloys. Journal of The Electrochemical Society
2008,
155(2), D104-D109.

3. Catrangiu, A. S.; Sin, I.; Prioteasa, P.; Cotarta, A.; Cojocaru, A.; Anicai, L.; Visan, T., Studies of antimony telluride and copper telluride films electrodeposition from choline chloride containing ionic liquids. Thin Solid Films
2016,
611, 88-100.

4. Jung, H.; Myung, N. V., Electrodeposition of antimony telluride thin films from acidic nitrate-tartrate baths. Electrochimica Acta
2011,
56(16), 5611-5615.

5. Gunawardena, G.; Hills, G.; Montenegro, I.; Scharifker, B., Electrochemical nucleation. Journal of Electroanalytical Chemistry and Interfacial Electrochemistry
1982,
138 (2), 225-239.

Figure 1