bluuebunny/crossref_metadata_2025 huggingface dataset:
Charging Lithium-Oxygen Battery Via Protic Solvent-Enhanced Redox Shuttle Mechanism
Authors: Shen Yue , Zhang Wang , Huang Yunhui
Published: February 2020

Lithium-oxygen battery has the highest theoretic energy density among all rechargeable batteries. But its discharge product Li2O2 is difficult to be oxidized back in the charge process, which causes high charge overpotential, serious electrolyte decomposition and poor cyclability. An effective way to solve this problem is adding redox mediator (RM) in the electrolyte to catalyze the charge reaction via a solution phase process. However, the reaction kinetics between the oxidized RM and Li2O2 is seldom investigated. Here, taking iodine species as the model RM, we find that the efficiency of the solution phase catalysis is limited by the reaction rate between the oxidized RM and Li2O2, which is largely dependent on the electrolyte solvent. Protic solvents, such as water and alcohols lead to high reaction rate because of the hydrogen bond induced solvation of Li2O2. However, too high proton activity may also bring unwanted peroxide disproportionation. Among a series of alcohols, n-butanol is found to show proper proton activity and significantly improves the solution phase catalytic efficiency.

Some issues on objectively evaluating the cathode performance of lithium-oxygen battery will also be discussed in this talk. Because of the complexity of the multi-phase electrochemical reaction, conventional half-cell testing methods and parameters to evaluate the performance of lithium-ion cathodes are not suitable for lithium-oxygen cathodes. It is common to use unlimited lithium and unlimited oxygen in half-cell tests. But such tests are just testing the “reusability of the catalyst” instead of the “reversibility of the electrochemical reaction”. The result cannot objectively reflect the parasitic reactions. To objectively evaluate the electrochemical reversibility, we propose a Li2O2-graphite cell with limited amount of lithium-ion. Such configuration can eliminate the “fake reversible capacity” caused by parasitic cathodic reactions, and thus is more reliable. We found that the real reversible ratio of the cathode reaction is much improved with the presence of redox mediator and butanol, but still far from satisfactory.

ref:

1. Shen, Y.; Zhang, W.; Chou, S.-L.; Dou, S.-X. Science
2016, 352, 667.

2. Sun, D.; Shen, Y.; Zhang, W.; Yu, L.; Yi, Z.; Yin, W.; Wang, D.; Huang, Y.; Wang, J.; Wang, D.; Goodenough, J. B. J. Am. Chem. Soc.
2014, 136, 8941.

3. Zhang, W.; Shen, Y.; Sun, D.; Huang, Z.; Zhou, J.; Yan, H.; Huang, Y. Nano Energy
2016, 30, 43.

4. Zhang, W; Shen, Y. ; Sun, D.;Huang, Z.; Huang, Y. Adv. Energy Mater.
2017, DOI:aenm201602938.
(Battery Division Technology Award) Requirements and Approaches for Next Generation Battery Technologies for Energy Storage and Transportation
Authors: Liu Jun
Published: February 2020

Energy storage is critical for modern computation and communication, grid modernization and electrification of transportation infrastructure. Developing high energy and low cost batteries with improved safety is a high priority. Among many options, redox flow batteries are scalable for large scale applications, and advanced lithium batteries, Li metal anode coupled with high Ni NMC, and Li-S systems, have the potential to reach an energy density higher than what is available in today’s Li-ion batteries. However, these next generation energy systems need to push the limits of the materials properties, and the materials and components need to be optimized on the cell level to allow high efficiency utilization of the active materials (high utilization). Several common challenges will be addressed including: (1) enabling high efficiency utilization of Li metal, (2) increasing active materials loading, reducing parasite mass and inactive components, (3) controlling fundamental electrochemical reaction mechanisms, (4) increasing the stability window, and (5) reducing undesirable interfacial reactions and cross contamination from the cathode to the anode. Under high utilization conditions, the fundamental failure mechanisms may also differ from the experimental conditions widely studied in the literature. Potential approaches to overcome the barriers will be discussed.
Investigation of a Carbon Nanotube-Encapsulated Fe1−Xs Composite as Anode for Sodium-Ion Batteries
Authors: PARK Samgmin , Sun Yang-Kook
Published: February 2020

Owing to the long life span and high energy density, lithium-ion batteries (LIBs) have received worldwide application in our daily lives for powering portable devices and burdening electric vehicles (EVs) and hybrid EVs. A promising anode material consisting of Fe1−xS nanoparticles and bamboo-like carbon nanotubes (CNTs) has been designed and prepared by an effective in situ chemical transformation. The resultant Fe 1−xS@CNTs with a three-dimensional network not only provide high conductivity paths and channels for electrons and ions but also offer the combined merits of iron sulfide and CNTs in electrochemical energy storage applications, leading to outstanding performance as an anode material for sodium-ion batteries. When tested in a half-cell, a high capacity of 449.2 mAh g−1 can be retained after 200 cycles at 500 mA g−1, corresponding to a high retention of 97.4%. Even at 8000 mA g−1, a satisfactory capacity of 326.3 mAh g−1 can be delivered. When tested in the full cell, a capacity of 438.5 mAh g−1 with capacity retention of 85.0% is manifested after 80 cycles based on the mass of the anode. The appealing structure and electrochemical performance of this material demonstrate its great promise for applications in practical rechargeable batteries.
Study of the Zn Insertion into Nanostructured d-MnO2 in Non-Aqueous Metal Batteries Using in-Situ X-Ray Absorption Spectroscopy
Authors: Kim Soojeong , Han Sang-Don , Tepavcevic Sanja , Vaughey John T. , Fenter Paul , Fister Timothy T
Published: February 2020

Nonaqueous multivalent battery chemistries provide high theoretical volumetric capacity, limited dendrite formation, and wide electrochemical windows that are a promising alternative to traditional lithium-based energy storage materials. However, transport limitations and volume change have often restricted cathodes to nanophase materials. To better understand these structural changes, we have studied Zn intercalation in δ-MnO2 cathodes using X-ray absorption spectroscopy during charge and discharge. When paired with a zinc metal anode and a AN-Zn(TFSI)2 electrolyte, the MnO2 cathode provides excellent reversibility (~100% Coulombic efficiency) and stability for 50+ cycles with ~100 mAhg-1 capacity with an operating voltage of 1.2 V vs. Zn/Zn2+. In situ x-ray absorption spectroscopy (XAS) provides element-specific characterization of both crystalline and amorphous phases and enables direct correlations between electrochemical performance and structural/redox changes associated with Mn and Zn species while cycling. By looking at the main edge of the Mn K-edge XANES spectra, the δ-MnO2 samples show clear reversible changes in redox state upon Zn insertion and deinsertion which allows Mn absorption edge shifts systematically from left to the right while cycling. These redox changes can be correlated to the local structure at the Mn site using extended X-ray absorption fine structure (EXAFS). We find a substantial decrease in the first two coordination shells upon discharge and nearly complete recovery upon charge, which we attribute to Jahn-Teller distortions during reduction to Mn3+.
Large-Scaled Li-Air Batteries
Authors: Kang Jin-Hyuk , Sun Yang-Kook
Published: February 2020

Actual cell capacities of Li-air batteries are very low and, since only small-scale electrodes are currently tested, it is hard to predict the properties of large-size electrodes and cells, thus evaluating and judging real practical challenges related to this battery technology.1-3

In this report, we report on fabrication, operation and evaluation of pouch-type Li-air cells using 3×5 cm2 sized electrodes, in which we intend deal with higher capacity (mAh) of the electrodes, compared to most previous studies in the field. With the relatively large-sized cells, operating at high current density and capacity, we could recognize some remarkable problems that may not be significant in small cells.

In relatively large cells as those explored in this work issues related to non-uniform current distribution, mechanical and electronic integrity of electrodes are much more influencing compared to small cells. Hence, problems such as lithium dendrites formation and non-uniform deposition of oxygen reduction product become severe.

This study can help to determine which parameters are the most important for developing practical Li-air batteries.

 

References

1. K. M. Abraham, Z. Jiang, J. Electrochem. Soc.
1996, 143, 1.

2. H. G. Jung, J. Hassoun, J. B. Park, Y. K. Sun, B. Scrosati, Nature Chemistry
2012, 4, 579. 3.

3 M. M. O. Thotiyl, S. A. Freunberger, Z. Peng, Y. Chen, Z. Liu, P. G. Bruce, Nature Materials
2013, 12, 1050.
MnCo2O4 Anchored on Magneli Phase Titanium Oxide As a Non-Carbon Cathode for Li-O2 Batteries
Authors: Yang Ruizhi , Cao Xuecheng , Sun Zhihui , Li Fan
Published: February 2020

Development of highly effective and environmentally friendly battery technology is crucial to the energy storage system and electronic vehicle.[1,2] Recently, the aprotic lithium-oxygen (Li-O2) battery has attracted much attention due to its high specific energy density of 3500 Wh kg-1 (based on the mass of Li2O2) and a favorable potential of 3.0 V, which are defined by the chemistry of the reversible reaction Li + O2 ↔Li2O2.[3,4] The high specific energy density of Li-O2 battery renders it a promising candidate for the electrical vehicle with extended-range driving. One of the challenges in Li-O2battery is to find a catalyst that can improve the sluggish electrochemical kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during the discharge and charge process, respectively.[5]

Herein, we employ Magneli phase Ti4O7 as a support and construct a hybrid with MnCo2O4 (MCO) nanoparticles being anchored on the surface of Ti4O7 for the first time. This hybrid is employed as a non-carbon cathode material for Li-O2 batteries. The synergistic interaction between Ti4O7 support and MCO nanoparticles further promotes the catalytic activity and stability of the hybrid. Benefiting form these advantages, the as-synthesized Ti4O7-MCO hybrid exhibits excellent catalytic activity to decrease the voltage gap between discharge and charge. The Ti4O7-MCO presents excellent discharge performance when compared with other carbon-free cathode materials. Moreover, due to the excellent chemical durability of Ti4O7 in organic electrolyte and the interaction between Ti4O7and MCO, the hybird is very stable during the battery cycling without agglomeration and detachment.

The Discharge/charge profile, rate capability and cycling performance of Ti4O7-MCO are shown in Figure 1.

 

 

Figure 1.  (a) Discharge/charge profile of Ti4O7-MCO cathode under different current densities; (b) First discharge/charge profile of Ti4O7-MCO, Ti4O7, C and C-MCO with a limited capacity of 500 mAh g-1; (c) Cycling performance of Ti4O7 cathode; (d) Cycling performance of Ti4O7-MCO cathode.

 

Acknowledgements

This work is supported by National Natural Science Foundation of China (51572181), the National Key Research and Development Program of China (2016YFB0100200)，Natural Science Foundation of Jiangsu Province, China (BK20151226).

References

[1] A. S. Arico, P. Bruce, B. Scrosati, J. M. Tarascon, W. Van Schalkwijk, Nat. Mater. 4(2005)366.

[2] P. G. Bruce, S. A. Freunberger, L. J. Hardwick, J. M. Tarascon, Nat. Mater. 11(2012)19.

[3] G. Girishkumar, B. McCloskey, A. C. Luntz, S. Swanson, W. Wilcke, J. Phys. Chem. Lett. 1(2010) 2193.

[4] F. Y. Cheng, J. Chen, Chem. Soc. Rev. 41(2012)2172.

[5] Z.-L. Wang, D. Xu, J.-J. Xu, X.-B. Zhang, Chem. Soc. Rev. 43(2014)7746.

Figure 1
Study of Porous Carbon Nanofibers As Interlayer and As Standalone Binder-Free Sulfur Hosts for Li-S Batteries
Authors: Kalra Vibha
Published: February 2020

In the first part of the talk, I will present our work on study of free-standing porous carbon nanofibers with tunable surface area and pore structure as an interlayer between the sulfur cathode and the separator to inhibit the shuttling of the intermediate polysulfides in lithium–sulfur (Li–S) batteries. Specifically, the effects of thickness, surface area, and pore size distribution of carbon nanofiber (CNF) interlayers on the performance of Li–S batteries have been studied. The carbon nanofiber interlayer not only reduces the electrochemical resistance but also localizes the migrating polysulfides and traps them, thereby improving the discharge capacity as well as cyclability. A high initial discharge capacity of up to 1549 mA h g−1 at C/5 rate, which is 92% of the theoretical capacity of sulfur, with 98% average coulombic efficiency and 83% capacity retention after 100 cycles was obtained.

In the second half of the talk, I will discuss our work wherein we directly incorporate sulfur into the carbon nanofibers as a host using an ultra-rapid (5-second) deposition technique. This procedure melts sulfur into carbon nanofiber mats, which play a significant role as a built-in current collector to provide uninterrupted electron transport pathways throughout the electrode without hindrance of insulating binding agents, thereby eliminating the need for any dead weight from the binders, interlayer or current collector. The large inter-fiber spacing facilitates electrolyte diffusion and provides sufficient space for the volume expansion during lithium-sulfur redox. The cathodes exhibit highly stable discharge capacities at 0.5C with 100% capacity retention over 150 cycles (~550 mAh g-1 after conditioning). This technique completely eliminates the need for slurry-based processing including the insulating binders, toxic solvent, or heavy current collector, producing an effective capacity of ~991 mAh g-1 at 0.5C over 150 cycles. Moreover, conventional sulfur melt deposition techniques require high temperatures (155-300 °C) and are very time consuming (~8-10h) while this ultra-rapid technique requires only 140 °C, 5 seconds, and a small application of pressure (~200 psi). The ultra-rapid method offers a practical approach to sulfur cathode fabrication into simple fiber electrodes compared to conventional techniques that require time-consuming deposition to integrate sulfur into highly complex nanostructures. Furthermore, this free-standing nature of the nanofiber-based design demonstrates a feasible route for evolving technologies like smart fabrics and wearable batteries.

Relevant Reference: Singhal, R.; Chung, S-H.; Manthiram, A.; Kalra, V. Free-standing Carbon Nanofiber Interlayer for High Performance Lithium-Sulfur Batteries. Journal of Materials Chemistry A, 2015, 3, 4530.
New Findings on the Lithium Ion Conduction Behaviors Depending on Tilted Grain Boundaries in Garnet-Type Li7La3Zr2O12
Authors: Shiiba Hiromasa , Zettsu Nobuyuki , Jalem Randy , Nakayama Masanobu , Teshima Katsuya
Published: February 2020

Garnet-type Li7La3Zr2O12 (LLZO) and its derivatives are considered promising candidate materials for all-solid-state Li-ion batteries as solid electrolytes due to their high Li+ conductivities of around 10-4 S cm-1 at room temperature and wide electrochemical window. Despite the larger number of detailed studies utilizing various experimental and theoretical approaches, the experimentally evaluated Li+ conductivities did not precisely match the computationally predicted values. The discrepancy between the ion conductivities can be attributed to the ambivalent properties of grain boundaries (GBs). GB structure is a critical parameter that controls the macroscopic properties of materials. However, various technological limitations of both the experimental and theoretical approaches utilized for elucidating the Li+ conduction behavior of GBs have restricted our ability of reaching a deeper understanding of the processes occurring at the atomic level. In this study, we investigated the Li+conducting behaviors of various tilted GBs of cubic LLZO with a garnet framework by using molecular dynamics approaches.

Nine stoichiometric equilibrium GB models were used to determine Li+conductivity. It was found that the GB conductivity was smaller than the bulk one regardless of the orientation. In particular, the conductivities perpendicular to the GBs were characterized by the lowest values.

Some factors affecting Li conductivity near the tilted GBs may be related to their stability. The relationship between the structural distortions at the GBs and the Li+ conducting characteristics were evaluated in terms of the GB energies and radial distribution function for the La-La, Zr-Zr, and O-O interactions in the LLZO bulk and GBs. We found that the Li+ conductivities are highly correlate with the structural distortions at the GBs.

In order to elucidate the Li+ diffusion characteristics at the GBs in more detail, the variations of the atomic concentration near the GBs were calculated along the axis perpendicular to the GB surface. The atomic population at bulk region was constantly modulated, while that at GB region was anomalously dispersed. The average atomic concentration at the GBs was lower than that at the bulk. In particular, the observed decrease in the Li+ concentration suggests the formation of Li-deficient sites across the GB center, which represents the primary reason for the degraded ionic conductivity in the GB region. In fact, the Li ionic conductivity perpendicular to the GBs decreased with decreasing Li+ concentration at the GBs, which was caused by the slower diffusion of Li+.

Thus, preventing the distortion of the GB crystallographic structure and the related drop in the Li+concentration should be considered one of the top priorities when designing GBs with desirable properties.

Acknowledgement

This work was partially supported by CREST, JST Grant Number JPMJCR1322, Japan.
(Invited) Advancing Convergence and Innovation in Cancer Research: National Cancer Institute Center for Strategic Scientific Initiatives (CSSI)
Authors: Berny-Lang Michelle Anne , Hanlon Sean Erik , Lee Jerry Ssu-Hsien
Published: February 2020

The National Cancer Institute (NCI) Center for Strategic Scientific Initiatives (CSSI) has as its mission the task of planning, developing, executing, and implementing rapid strategic scientific and technology initiatives that keep the Institute ahead of the scientific curve with respect to potential new exciting areas and discoveries. This may involve the development and application of advanced technologies, synergy of large scale and individual initiated research, and/or forging novel partnerships that emphasize innovation, trans-disciplinary teams and convergence of scientific disciplines to enable the translation of discoveries into new interventions, both domestically and in the international arena, to detect, prevent and treat cancer more effectively. This presentation will highlight various programs and their associated accomplishments within CSSI’s broad scientific portfolio (Clinical Proteomic Tumor Analysis Consortium, Alliance for Nanotechnology in Cancer, Physical Sciences-Oncology Centers, Innovative Molecular Analysis Technologies, and Provocative Questions) and describe future directions and potential opportunities for biomedical engineering efforts in cancer research.
(Invited) Commercialization of Novel Electrochemical Sensors for Volatile Organics
Authors: Kuhr Werner , Rhodine Craig
Published: February 2020

A combination of thermal vaporization and solid phase extraction were used with a variety of different electrochemical methods for the analysis of phenolic molecules in plant materials. The direct electrochemical oxidation of the phenols using square wave voltammetry showed good linearity and adequate sensitivity, provided that freshly polished electrodes were used for each measurement. The oxidation of the phenol created a reactive product that quickly fouled the surface of the electrode and limited the method to the use of fresh electrode surfaces. The results obtained with this method are well correlated with GC analysis of the same samples. If fresh electrodes are not easily obtained, then an indirect electrochemical approach seems a realistic alternative. Although some fouling was observed, the indirect method had sufficient sensitivity and linearity to be useful for these measurements. The use of both fresh electrode surfaces, as well as indirect electrochemical detection, produced improved correlations with the spiked concentrations. This is likely due to the improved fidelity of the measurement, since a fresh surface is used each time and a minimum amount of fouling is produced by the measurement. The combination of these approaches will be used to produce a sampling tool and sensor array for the characterization of a variety of commercial agricultural products.
A Wearable Electrochemical Sensor to Monitor Progression of Wound Healing
Authors: RoyChoudhury Sohini , Umasankar Yogeswaran , Bhansali Shekhar
Published: February 2020

An enzymatic electrochemical biosensor comprising the enzyme, urate oxidase (uricase, UOx), has been investigated for detection of real-time changes in uric acid. Uric acid is a key biomarker for monitoring severity of wounds, a complex process initiated to restore tissue damage.1 Although, tracking wound healing continues to be a challenge in healthcare; it is equally demanding. In existing technology, the time taken from the appearance of a wound to the commencement of an effective wound management plan can be lengthy, as laboratory tests can take days to complete. With its presence in different bio-fluids2, this work explores the continuous monitoring of systemic uric acid in human sweat. Electrochemical techniques like cyclic voltammetry and differential pulse voltammetry have been investigated for evaluating the success of the sensor on a wearable platform as a surrogate for wound healing. On this biosensor, hydrolysis of UA was monitored to detect the oxidation of its byproduct, H2O2. Results show that the use of a redox electron shuttle such as ferrocene carboxylic acid (FCA) or metal nano-particles enable electron transfer between the active site of the enzyme and the electrode. This work explores the possibilities of embedding the biosensor in wound dressing-gauze materials as substrates and investigates the effect and role of metal nano-particles on detection. It can measure very low volumes (0.5uL) of sweat showing that such low volumes are sufficient for systemic detection of uric acid at the wound vicinity. This non-invasive approach holds promise for tracking wound chronicity and can be beneficial towards shorter hospitalization time, costs and reduced outcomes of trauma, surgery, and amputations.3 The developed biosensor could facilitate treatment with an improved, comprehensive understanding of the recovery processes associated with healing.

References

1. R. A. Nery, B. S. Kahlow, T. L. Skare, F. I. Tabushi, and A. do Amaral e Castro, Arq. Bras. Cir. Dig., 28, 290–2 (2015).

2. X. Dong, Intl. J. Of Pharmaceutical Sciences And Research, 8, 925-29 (2017).

3. Cobb, M. J.; Chen, Y.; Underwood, R. A.; Usui, M. L.; Olerud, J.; Li, X., J. Biomed. Opt., 11, 064002 (10.1117/1.2388152) (2006).
The Synthesis and Application of Llzo Ultrathin Electrolyte Film
Authors: Yan Xufeng , Li Zhuobin , Han Weiqiang
Published: February 2020

Compared with a conventional lithium-ion battery, all-solid-state battery exhibits excellent safety, which is the one of drawbacks of the conventional lithium-ion battery. The Garnet electrolyte Li7La3Zr2O12 (LLZO), as the typical representative of solid electrolyte, shows outstanding safety and electrochemical stability.

During the process of this work, the LLZO underwent the changes from micro-sized particles, nano-particles slurry, and the final ultrathin film. The micro-sized particles was obtained by the conventional solid state reaction. Nanoscale LLZO slurry was prepared using high energy ball-milling technology, with the addition of 1-Methyl-2-pyrrolidinone, LiN(CF3SO2)2, SPEEK-PSI-Li and Piuronic®F127. The LLZO ultrathin electrolyte film was obtained by the method of wet coating and drying out the solvent of LLZO slurry.

The as-prepared LLZO ultrathin film, with a thickness of several micrometers, was applied in the cell of Li/LLZO/LFPO. At room temperature, the battery showed a capacity of 160.4 mAh g-1 for the first discharge, which was about 94.4% of the theoretical capacity value. After 100 cycles, the cell provided a discharge capacity of 136.8 mAh g-1. At 60 ℃, the battery presented more stable electrochemical performance. The capacity loss during the cycles form the 2nd to 100th was only 0.06% (0.7 mAh g-1). The excellent performance could be attributed to the ultrathin solid electrolyte film.
Importance of Electronic Conductivity in the Reversibility and Rate Capability of Metal Oxide Lithium Battery Anodes
Authors: Palmieri Alessandro , Ng Benjamin , Oliveira Alexandra , Mustain William E.
Published: February 2020

Lithium ion batteries are the leading technology in the portable electronic market; however, in order to make the transition from laptops and tablets to automobiles and grid storage, materials with higher volumetric and specific energy density are needed. Therefore, new Li battery materials is an area of intensive research focus. At the anode, graphite has served well as the ubiquitous choice for commercial electrodes to date due to the high reversibility of Li intercalation, which resulted in very high stability and cycle life. However, the theoretical capacity of graphite is low, and it is possible that graphite-utilizing lithium batteries may be not be able to meet targets for emerging applications. Therefore, new solutions have to be investigated to increase the energy density of lithium ion batteries, while not sacrificing their stability and cycling performance compared to modern cells.

In recent years, our group has focused on advancing metal oxide-based anode materials toward automotive targets. To reach these targets, it is important to investigate and understand the key parameters that increase reaction reversibility and rate performance. In this poster, we will show how the active material electronic conductivity plays a critical key role in both cycling performance and stability of metal oxide anodes. The electronic conductivity was controlled by adding advanced carbons (i.e. reduced graphene oxide and carbon nanotubes) to increase the inter-particle conductivity, while the intrinsic conductivity of the active material was manipulated by doping. Both of these strategies will be discussed.

More quantitatively, the electronic conductivity was probed by the Van Der Pauw Method and tied directly to the cycle life of lithium cells collected by chronopotentiometric charge/discharge curves. The nanostructural changes of the active materials were investigated by high resolution transmission electron microscopy (TEM), including identical location TEM. Finally, applying the lessons learned from these experiments, highly stable full cells with a metal oxide anode and lithium cobalt oxide cathode were achieved.
Synthetic Control of Crystallite Size of Silver Vanadium Phosphorous Oxide (Ag0.50VOPO4·1.9H2O): Impact on Electrochemistry
Authors: Huie Matthew M. , Takeuchi Esther S , Takeuchi Kenneth J , Marschilok Amy C
Published: February 2020

This report describes a synthetic approach to control the crystallite size of silver vanadium phosphorous oxide, Ag0.50VOPO4·1.9H2O, and the impact on electrochemistry in lithium based batteries. Ag0.50VOPO4·1.9H2O was synthesized over a range of temperatures. X-ray diffraction (XRD) was used to confirm the crystalline phase and the crystallite size sizes. Particle size and morphology were characterized using scanning electron microscopy and surface area measurements. Galvanostatic reduction and intermittent discharge were used to evaluate functional capacity and resistance. This systematic study of electrochemistry and material properties shows that deliverable capacity and cell resistance are impacted by both interparticle and intraparticle transport properties.
Enhanced Cycle Performance of MnO2 Supercapacitors By Ultrasonic-Assisted Electrodeposition
Authors: Xu Cheng , Liu Jikang
Published: February 2020

Among the various inexpensive and environmentally friendly candidates for supercapacitors, MnO2 has been investigated extensively due to its outstanding comprehensive performance. However, MnO2 exhibits poor cycle performance in many research work, which may possibly due to the dissolution of MnO2 during charge-discharge cycles. In this work, we report a facile and effective method to improve the cycle performance of MnO2 films by ultrasonic-assisted electrodeposition.

The MnO2 films were electrodeposited on Ni foam substrates without treatment (denoted as sample I), with post-ultrasonic treatment (denoted as sample II) and synchro-ultrasonic treatment (denoted as sample III). The structures of the MnO2 films are characterized by SEM and TEM. MnO2 nanowire clusters and nanosheet arrays can be observed in the samples prepared by post-ultrasonic assisted and synchro-ultrasonic assisted electrodeposition, respectively, while irregular nanosheets are inspected in the samples without ultrasonic assistance. The electrochemical testing of cyclic voltammetry (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) measurements show typical pseudocapacitive behaviors for all samples. Directly electrodeposited MnO2 film without ultrasonic assistance suffers from obvious attenuation in capacitance, which decreases about 37% from 230 F g-1 in 3000 cycles. Comparatively, the ultrasonically treated MnO2 films exhibit a maximum specific capacitance of 369 F g-1 and 325 F g-1 at 1 A g-1, respectively, which can maintain 98% and 86% up to 3000 cycles, respectively. The effects of the deposition current and ultrasonic time were also investigated. The enhancement in electrochemical performance is significant for the samples with ultrasonic-assisted treatment, suggesting the treated MnO2 films to be a promising choice for supercapacitors.

Figure 1
Nickel Nanocluster Loaded Black Titania for Photocatalytic Reduction of CO2 into Solar Fuels: Computational and Experimental Studies
Authors: Reta Tadesse Billo , Fu Fang-Yu , Raghunath Putikam , Shown Indrajit , Chen Wei-Fu , Shen Tzu-Hsien , Lin M.C. , Lee Chih-Hao , Hwang Jih-Shang , Chen Li-Chyong , Chen Kuei-Hsien
Published: February 2020

The conversion of atmospheric carbon dioxide (CO2) into solar fuels by imitation of a natural photosynthesis using only water vapor and sunlight for energy has attracted widespread attention recently. One of the key challenges is to design a photocatalyst that can bind and activate the CO2 molecule with smallest possible activation energy and produce selective solar fuel production. In this contribution, we report a combined experimental and computational studies on Ni nanocluster loaded black TiO2 (Ni@TiO2[Vo]) with built-in dual active sites for selective photocatalytic CO2 conversion. Our findings reveal that, the synergistic effect of deliberately induced unsaturated Ni nanocluster and oxygen vacancies provide (1) energetically stable CO2 binding sites with lowest activation energy (0.08eV), (2) highly reactive sites, (3) fast electron transfer pathway, (4) enhanced light harvesting by lowering the band gap. The Ni@TiO2[Vo] photocatalyst has demonstrated highly selective and enhanced photocatalytic activity of more than 18 times higher solar fuel production than the commercial TiO2 (P-25). An insight to the mechanism of interfacial charge transfer and product formation mechanism are explored. The proposed approach to adsorb and activate CO2 molecule on dual active sites can be applied to design other catalysts for photocatalytic CO2 reduction.
Biomass-Derived Porous Carbon As Noble-Metal Free Catalysts for Oxygen Reduction Reaction
Authors: Culhane Casey , Liu Xiaojun , Zou Shouzhong
Published: February 2020

Efficient electrocatalysts for the oxygen reduction reaction (ORR) play a critical role in the performance of fuel cells. In this work, biomass-derived porous carbon was prepared by a facile procedure based on simple pyrolysis of spinach at controlled temperatures (700 – 900 °C) and different activation agents. The obtained porous carbon exhibited high specific surface area and porosity. Electrochemical measurements showed that the porous carbons possessed a high electrocatalytic activity for ORR in alkaline media. The ORR onset potential for the catalyst is +0.96 V vs. RHE. Moreover, it showed excellent long-term stability, and methanol tolerance, as compared to the commercial Pt/C. The catalytic performance of porous carbon obtained by various activation agent will be compared. The results suggest a very promising route towards the development of value-added carbon materials for effective cathode catalysts for alkaline fuel cells.
(Invited) Next Generation Strategy for Reproducible, Compliant Microelectrode Arrays
Authors: Pancrazio Joseph J. , Voit Walter E , Capadona Jeffrey R
Published: February 2020

Implantable MEAs are an essential tool for the elucidation of the functional circuitry of the brain. These devices offer a means of simultaneously recording from neurons to elucidate modular and hierarchical processing, as well as neural circuitry involved in adaptation. In addition, MEAs have the potential to serve as a clinical neuroprostheses. MEAs implanted in cortex record from motor regions to enable control of devices, systems, and can restore control of the patients own paralyzed limbs when combined with functional electrical stimulation systems. The majority of MEAs, and especially those that are available commercially, are fabricated from silicon and leverage techniques associated with integrated circuit microfabrication and packaging. Using industry standard approaches, the features of MEAs can be reproducibly created and the resulting devices can be manufactured and disseminated. Two well-known approaches are MEAs initially developed at the University of Utah and at the University of Michigan now available to the neuroscience research community through Blackrock Microsystems and Neuronexus, respectively.

It is now widely understood that these devices exhibit limited long term viability where recordings fail after 6 months – 1 year after implantation. One of the causes for this failure is believed to originate from the chronic foreign body response from microglia and astrocytes which extends well beyond the normal acute inflammatory response following initial implantation. This foreign body response has often been attributed, in large part, to the mechanical mismatch that exists between the MEAs and the surrounding brain tissue as well as the feature size of the MEAs. In this presentation, we will discuss a novel type of MEA that achieves compliance by material properties, specifically MEAs created from shape memory polymers (SMPs) where formulations allow tunable and dynamic mechanical properties. SMPs can be fabricated which are stiff at room temperature, but soften by 1-2 degrees of magnitude once inserted in the brain. This strategy, which leverages conventional photolithography, can be utilized to create devices customized for recording and stimulation within cortical and deep brain regions. An important aspect of this strategy is that it provides a pathway for translation and dissemination of novel, manufacturable neurotechnology. This presentation will provide an overview of work to date to create and demonstrate compliant and flexible MEAs and the electrochemical characterization of these devices both in vitro and in vivo.
(Invited) Long-Term Viability of Optogenetically Transfected Neurons and Implantable Electrodes in the Motor Cortex of Mice
Authors: Gorini Christopher , Koo Beomseo , Altimus Cara , Civillico Eugene
Published: February 2020

Neurological disorders and injuries can result in paralysis and involuntary muscle contractions that interfere with speech, movement and activities of daily living. Current approaches to reduce these dysfunctions, such as selective surgical ablation, oral medications, or electrical stimulation, have important limitations including lack of action or behavioral specificity. There is currently no treatment for spasticity or paralysis that provides targeted, tunable and rapidly reversible control of fine muscle activity. Recently, implantable cortical electrodes have been targeted as a potential therapy for fine control of robotic prosthesis. Implanting these electrodes in the motor cortex has shown promise, however development of long-term systems has yet to be fully understood and the effects of the broad electrical stimulation produced by these devices is still unclear. Optogenetics, a technique that uses light to modulate cells, may provide some relief in producing a stable, long-term intracortical implant with high specificity. Although optogenetic technology has proven to be effective as a research tool and shown promise acutely as a therapeutic intervention in preclinical work, few studies have utilized optogenetics for chronic applications. There is a paucity of knowledge regarding the stability of opsin expression or the neuronal network response to repeated optical stimulation over time. In order to contribute to the understanding of the long-term effects of intracortical devices and optogenetic gene therapy, we performed bilateral injections of an Adeno-associated viral delivery system to transfect the excitatory opsin, channelrhodopsin-2 (ChR2), into the motor cortex of mice. We then unilaterally implanted a 16 channel shank recording optrode into one of the previously injected cortical hemispheres. Following recovery from surgery, spontaneous cortical activity was recorded in freely moving mice. During recording sessions the cortex was illuminated with pulsed 473nm laser light at a variety of frequencies to excite ChR2+ motor neurons. After 8-12 months of weekly recordings, animals were sacrificed and tissue analyzed for changes in microglia response, neuroinflammation, or morphology.
Clay Coating Systems for Removal of Heavy Metals for Waste Water
Authors: Blersch David , Beidaghi Majid , Davis Edward
Published: February 2020

Algae turf scrubbers and other biological methods to purify polluted waters hold promise for simultaneously removing excess nutrients and producing a potentially valuable biomass crop. The harvested biomass can be used for fuel production, animal feed, or in some cases a direct food source. However, when applied to industrial waste waters contaminated with heavy metals such as lead, cadmium, and chromium VI the use of the biomass is limited. Thus, a system to remove heavy metals from these waters prior to biological filtration is required. In an industrial setting, several methods are applied for the removal of heavy metals including membrane filtration, electrolytic reduction, and ion-exchange reactions. Adsorption methods are particularly attractive owing to the possibility of regeneration and reuse. Halloysite nanotubes, a weathered smectite clay, have been investigated for adsorption of several heavy metals. Here we propose the use of a crosslinked Halloysite network for the adsorption of heavy metals from waste streams. A thermally reversible Diels-Alder reaction scheme is used to crosslink Halloysite nanotubes and allows for the system to be cast into multiple configurations such as coating and porous membranes with high Halloysite loadings. Halloysite nanotubes were modified with 3-(2-Furyl)propanoic acid or 11-maleimido-undecanoic acid. Mixtures of these materials were solution cast resulting in crosslinked Halloysite films and membranes. These systems were evaluated for heavy metal adsorption capacity and rate.
Design, Simulation and Fabrication of a Novel Phage Filter for Pathogens Testing from Large Volumes of Water
Authors: Lu Xu , Du Songtao , Horikawa Shin , Liu Yuzhe , Chen I-Hsuan , Wikle Howard Clyde , Xi Jianguo , Suh Sang-Jin , Chin Bryan Allen
Published: February 2020

In this paper, a phage filter has been developed to capture, concentrate and isolate small numbers of pathogens from large volumes of water. The phage filter consists of a magnetized filter frame and hundreds of phage-coated filter elements made of a magnetostrictive material. ANSYS Maxwell magnetostatic simulations have been conducted on filter designs. A prototype filter frame in the size of 2″ has been made of a PMMA pipe and Permalloy 80 wire. Two permanent magnets were used to generate a uniform magnitude of magnetic flux density and a desired direction of flux vectors to align and hold a high density of filter elements. The filter elements in the size of 4 mm × 0.8 mm × 30 µm were made of Metglas 2826MB ribbon by mechanically dicing. The experimental results were compared with the simulation models to improve the filter design.
Detection of Bacillus Anthracis Spores in Water Using a Phage-Coated Piezoelectric Membrane
Authors: Lu Xu , Wang Liang , Hou Lei , Cheng Zhongyang
Published: February 2020

Piezoelectric membrane, working as resonant device, was introduced as biosensor platform. The principle of this device is based on the frequency response of mass load due to the capture of anthracis spores by phage immobilized on the membrane surface. The responses of membrane in anthracis spores solutions were experimentally studied. It was found that the sensitivity of detection can be improved by using smaller membrane or by using high resonant mode of the membrane, which is in good agreement with the theoretical analyses.
Hexagonally Arranged Ag-Hemisphere Arrays with Rough Surface and the SERS Detection to Persistent Organic Pollutants
Authors: Tang Haibin , Meng Guowen , Wu Nianqiang
Published: February 2020

Persistent organic pollutants (POPs) are highly toxic and harmful to human health and the ecological environment. As such, the rapid trace detection to POPs is very important. The surface enhanced Raman scattering (SERS) effect of nanostructures can greatly enhance the intrinsic Raman signal of these pollutants with rapid response. This is expected to achieve rapid trace detection to POPs using SERS spectrum technique, overcoming the shortcomings of traditional detection methods.

One of the most important challenges is to fabricate SERS substrates with high SERS activity and uniform signal response. Herein, we have fabricated orderly hexagonally arranged Ag-hemisphere arrays with rough surface (Ag nanoparticle@Au nanopartilcle, urchin-like Ag hemisphere, and flower-like Ag submicron particles) using anodic aluminum oxide (AAO) templates. These nanostructures show high SERS sensitivity and uniform signals for the detection of plasticizer molecules and polychlorinated biphenyls (PCBs, a type of POP).
Simultaneous Detection of Tumor-Specific Circulating DNA Mutation and Methylation
Authors: Zhou Lang , Chin Bryan A , Simonian Alex
Published: February 2020

Almost half of cancer patients are diagnosed late. Early cancer detection in asymptomatic patients will improve the chances of treatment as well as patient outcomes. Lung cancer is the number one cause of cancer deaths for both genders worldwide. Various biomarkers can be used for the early diagnosis of lung cancer, among which circulating tumor DNA (ctDNA) has possibly become the most efficient biomarker. As the most widely used approach, PCR-based assays have the limitations such as long duration, labeling requirement, complicated operation, and high cost. More importantly, PCR-based assay is unable to detect the mutation and methylation degree of ctDNA simultaneously. To overcome these limitations, a novel method was developed for measurement of mutation and methylation of ctDNA, combining the concept of Electrochemical Proximity Assay (ECPA) with our newly developed Multi-Parametric/Multimodal Apparatus System (MPMS). MPMS couples three surface characterization techniques- surface plasmon resonance, electrochemical and fluorescence spectroscopies. The fluorescence intensity indicates the methylation degree, and the current peak implicates the amount of mutated lung cancer ctDNA while the resonance angle change of SPR characterizes the kinetics of each component involved in the assembly of the biosensor. This developed method offers not only high accuracy, sensitivity and specificity, but the information on the kinetics and thermodynamics in the sensor preparation and assembly.
Artificial Cilia for Capture and Sampling
Authors: Hanasoge Srinivas , Hesketh Peter , Alexeev Alexander , Ballard Matt , Erickson Marilyn , Xu Jie
Published: February 2020

There is a need for improved methods of pre-concentration and detection of bacteria in food safety. The sample preparation is necessary to increase the number of target bacteria in a fluid sample to improve the limit of detection. We show the use of metallic thin films as artificial cilia for applications in sample manipulation in microfluidics and biosensors. We use evaporated alloy of nickel-iron on a glass substrate which are actuated magnetically by varying the external magnetic field. These hair like synthetic structures actuated by the magnetic field have a highly asymmetric bending patterns in an oscillatory cycle. This asymmetry is important for creating any microfluidic transport. In this work, we exploit this asymmetry in the strokes and demonstrate microfluidic transport phenomenon of pumping, rapid mixing and capture of micro-particles in a microchannel.

To characterize the microfluidic pumping capabilities of the artificial cilia, we incorporate the cilia inside a PDMS microchannel loop and analyze the flow in produces. We vary important parameters such as the cilia width, spacing, number of rows and channel dimensions and establish its influence on the pumping efficiency. We observe low pumping rates at very high and very low operating frequencies, and establish an optimum operating frequency for maximized pumping efficiency.

Further, we demonstrate the use of such cilia for microfluidic mixing. For this, we use a PDMS Y-channel with cilia on its bottom wall. Two fluids dyed with different fluorescent colors are introduced into the two inlet channels. And the ability of the cilia to mix the two streams of fluid is characterized by imaging the fluorescent intensity of the fluid stream downstream from the cilia. Again, we show the dependence of mixing efficiency on several parameters of the system.

We also demonstrate particle capture with these artificial cilia. To do this, we functionalize the cilia with streptavidin protein, and introduce particles coated with biotin into the microchannel. The cilia is then oscillated so as to produce mixing in the microchannel. The mixing effect increases the probability of particles coming in contact with the cilia. The biotin coated particles stick to the cilia when they come into contact. This demonstrates capture of particles in a microfluidic channel. These microfluidic functions find varied application in many lab on a chip devices where active fluid transport is needed.