bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrolytic Deposition of Cisplatin on Magnesium for Biomedical Applications
Authors: Tsai Min Chen , Lai Yu-Liang , Hsu Shin- Ru , Yen Shiow Kang
Published: February 2020

Cancers cause death. Recently, many studies focus on the localized treatment to reduce the side effects of chemotherapy. In this research, the cisplatin has been successfully deposited on pure Mg specimen, degradable and promising for the tumor treatment by its local sustaining release to prevent the cancer from metastasis and even to achieve its apoptosis. In the experiment, the cathodic polarization tests coupled with electrochemical reactions in various concentrations of cisplatin solutions were analyzed to speculate the deposition mechanism of cisplatin, spectrophotometer (UV visible spectrometer) to measure cisplatin loading and release, Fourier transform infrared spectroscopy (FTIR) for chemical bonding of composites, field emission scanning electron microscope (FESEM) and focused ion beam (FIB) to observe surface and cross-section morphology, and energy-dispersive X-ray spectroscopy (EDS) to analyze constituent elements. The drug, cisplatin, is deposited on the pure Mg through exchanging Cl- with OH-, produced by the electrochemical method, to form strong hydrogen bonds for attracting one another. Besides, the drug loading on the post hydroxyapatite coated degradable Mg specimen with high porosity can be enhanced from 34.65 to 84.93 μg/cm2 and the drug sustaining release last for 3 weeks, which is promising for future clinical applications.
Surface Morphology of Copper Pulse Deposition in a Controlled Environment Using Microfluidic Device
Authors: Kawazoe Ryoma , Yamauchi Akira , Hayase Masanori
Published: February 2020

Pulse electrodeposited copper is known for its unique characteristics. Improvement of surface roughness [1] can be expected, since the deposit consists of finer sized grain compared to that made by using direct current [2] and the edge bead due to concentration distribution of plating solution can be suppressed. These advantages are available when nearly limiting current is applied, and it is difficult to make such optimal experimental condition steadily.

In this study, we used a micro fluidic device to control the concentration of cupric ion over the electrode. Pt electrode of 100 µm in diameter was used for the working electrode, and copper for the counter and reference electrode. We use transparent glass and photoresist for the micro channel, thereby, it is possible to observe the plating process with optical microscope, externally. Flow through micro channel forcibly becomes a laminar flow, so by controlling the flow velocity and ion concentration, we can calculate the ion distribution around the electrode. From the calculation and the pulse on-time, off-time, current density, we made a simulation to figure out the experimental condition that the cupric ion depletes at the vicinity of the electrode surface (Fig.1). Applying this, we can expect a fine nucleation, depositing randomly on the electrode every time the periodic current is applied, thus we can expect a smoother deposition surface compared to that obtained by direct current plating, since the surface roughness is suppressed. SEM (JEOL Carry Scope JCM-5100) was used to observe the surface morphology of the plating. Results indicates that pulse plating suppress the hump at the edge of the plating.

References

[1]M.J.Kim, T.Lim, K.J.Park, S.K.Cho, S.Kim, and J.J.Kim, J. Electrochem. Soc., 159(9) D538-D534 (2012)

[2]J.B.Marro, T.Darroudi, C.A.Okora, Y.S.Obeng, K.C.Richardson, Thin Solid Films 621 91-97 (2017)

Figure 1
Tailoring Organic Redox Couples for Non-Aqueous Redox Flow Batteries
Authors: Attanayake N. Harsha , Barton John Leonard , Casselman Matthew , Elliott Corrine F , Kaur Aman Preet , Kowalski Jeffrey A , Milshtein Jarrod David , Anthony John , Brushett Fikile R. , Landon James , Odom Susan A
Published: February 2020

Redox flow batteries (RFBs) are promising candidates for grid storage, but current systems have not met the stringent cost and/or safety requirements needed for widespread implementation. Replacing vanadium with organic compounds may lower materials cost, and utilizing non-aqueous (aprotic) electrolyte solvents, in place of water, could enable a 2- to 3-fold increase in operating voltage. Both features make non-aqueous RFBs candidates for large-scale stationary storage. A limited number of organic compounds have been reported as stable electron donors and acceptors, with even fewer materials being studied as small molecule two-electron donors and/or two-electron acceptors. Our recent efforts have focused on the development of highly soluble electron donors and acceptors with stable oxidized and reduced states. This presentation will focus on design strategies utilized to increase molecular stability in all relevant states of charge as well as solubility. In particular, we highlight the design, synthesis, and electrochemical analysis of organic redox couples. Results will be presented on the cycling of phenothiazine and naphthoquinone derivatives in flowing full cell battery prototypes.
Whole Blood CVD Diagnostics Using Portable FET Biosensor System
Authors: Sarangadharan Indu , Wang Shin-Li , Sukesan Revathi , Chen Pei-Chi , Dai Tze-Yu , Pulikkathodi Anil Kumar , Hsu Chen-Pin , Wang Yu-Lin
Published: February 2020

Cardiovascular diseases (CVDs) are the leading causes of death worldwide. Despite the scientific and technological advances in healthcare, CVD mortality rate has not improved significantly. Medical intervention in diseases such as myocardial infarction (MI) rely on detection of protein biomarkers from blood, which require sophisticated laboratory based instruments that are costly, extremely complex and time-consuming. The general unaffordability and inaccessibility of the current medical diagnostics contribute towards fatalities and medical complications. We have devised a portable biosensor system to detect protein based biomarkers from a single drop of whole blood, in 5 minutes, without any additional sample pre-processing or extra reagents. The sensing methodology is based on electrical double layer (EDL) gated field effect transistor (FET) biosensor, in which an array of gold electrodes designed as extended gate structures, transduce immunological interaction of target protein to readable electrical signal. High electric field modulation of transistor drain current enables very high sensitivity, selectivity and wide dynamic range, in whole blood. Single drop of blood is dropped on the device and blood cells are gravitationally separated from blood plasma during 5 mins of incubation period, by rotating the device orientation to face downwards. A portable sensor measurement unit is designed to record the electrical characteristics of the sensor and display the test results in interfaced personal computer. We have demonstrated the detection of cardiac troponin I (cTnI) and brain natriuretic peptide (BNP) in 1X PBS and clinical whole blood samples. The sensor methodology has been developed to considerably reduce cost and assay complexity, with minimal user protocols. This whole blood assay can be performed at the convenience of homes, offices and hospitals, by anyone without prior training, in 5 minutes.

Figure 1
(Invited) Rational Design of Nanomaterials for Electrochemical Energy Conversion and Storage
Authors: Sun Shuhui
Published: February 2020

PEM fuel cells are expected to play dominant role in future clean energy solutions for various applications. Developing highly efficient low-Pt and Pt-free catalysts are the key solutions for the wide-spread commercialization of PEMFCs. Through green chemistry and/or ALD techniques, we fabricated various novel Pt nanostructures, including nanowires, nanotubes, and single atoms. Compared to the conventional Pt nanoparticle/C commercial catalyst, these novel Pt nanostructures exhibited much enhanced activity (up to 10 times) and stability (up to 6 times) for fuel cells [1-7]. On the other hand, we recently developed novel Fe/N/C catalysts which exhibited higher activity in alkaline media and equivalent activity in acidic electrolyte compared to Pt. [8] Moreover, we systematically studied the decay mechanism of the MOF-based Fe/N/C catalyst, which is of significant important to improve the durability of Fe/N/C catalysts [9].

Both lithium-ion (LIB) and sodium-ion batteries (SIB) are promising technologies for energy storage. We developed a facile, inexpensive and scalable wet-chemical strategy to fabricate the Fe3O4/graphene composites and porous carbon spheres. The nanocomposite shows dramatically enhanced electrochemical properties including excellent reversible capacity, cyclability and rate performance in LIBs and SIBs [10,11].

References:

Sun, et al., Angew.
Chem. Int. Ed
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50, 422 (2011). (VIP+ Cover).

Sun, et al., Adv. Mater.,
20, 571(2008).

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20, 3900 (2008).

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19, 6376 (2008).

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Commun.,
45, 7048 (2009).

Sun, et al., Chemistry-A European Journal,
16, 829 (2010). (Inside Cover).

Zhang, et al., Scientific Reports, 3: 526 | (2013).

Li, et al., Advanced Functional Materials (2016).

Zhang, G, et al., Nano Energy, 2 (2016).

Fu, et al., J. Mater. Chem. A,
3, 13807 (2015).

Y. Fu, et al.,
RSC Advance. 6, 84149 (2016).
(Invited) Flexible, Foldable and Multi-Functional Paper-Based Electronics
Authors: Lin Chun-Ho , He Jr-Hau
Published: February 2020

Great advances have been made in developing cheap, simple, multi-functional and energy-saving fabrication processes for flexible electronics. Paper, as a flexible, foldable, cost-efficient and mass productive substrate, has shown diverse applications for flexible electronics to meet such demand. Recently, we have successfully demonstrated the first nonvolatile resistive memory using paper as substrates by means of all-printing techniques. Moreover, we also implemented the algorithm of Origami art into the device design for the flexible electronics, such as photodetectors and nanogenerators, taking advantage of the foldability and adaptability of paper substrates. In particular, paper origami triboelectric nanogenerators using paper as the starting material, with high degree of ﬂexibility, light weight, low cost, and recyclability is presented. We believe that these findings will pave a way for future energy harvesting and sensor design, especially for the development of green flexible electronics.
(Invited) Flexible Tactile Sensors for Wearable Healthcare Monitoring Devices
Authors: Ko Hyunhyub
Published: February 2020

Flexible tactile sensors with high force sensitivities have gained great attentions in the fields of wearable devices, robotic skins, and biomedical diagnostics. In human fingertip skins, fingerprint patterns and interlocked epidermal-dermal microridges have critical roles in amplifying and transferring tactile signals to various mechanoreceptors, enabling spatio-temporal perception of various static and dynamic tactile signals. Here, mimicking the structures and functions of fingertip skin, we introduce highly-sensitive, multifunctional, and stretchable electronic skins.

Inspired by the interlocked microstructures found in epidermal-dermal ridges in human skin, piezoresistive interlocked microdomes are employed for the demonstration of stress-direction-sensitive, stretchable electronic skins. We show that interlocked microdome arrays possess highly direction-sensitive detection capability of various mechanical stimuli including normal, shear, stretching, bending, and twisting forces. We also demonstrate that ferroelectric skins with fingerprint-like patterns and interlocked microstructures can detect and discriminate multiple spatio-temporal tactile stimuli including static and dynamic pressure, vibration, and temperature with high sensitivities. For applications, we demonstrate that stretchable electronic skins attached on the human skin can be used as wearable healthcare monitoring devices, which are able to distinguish various mechanical stimuli applied in different directions, selectively monitor different intensities and directions of air flows and vibrations, and sensitively monitor human breathing flows and voice vibrations. In addition, dynamic touch sensing ability is employed for the precise detection of acoustic sounds, and discrimination of various surface textures. Finally, for multifunctional wearable and skin-attachable devices, we show smart adhesive pads with temperature-responsive adhesion properties and force-dependent color changing touch screens based on mechanochromic surface coatings.
Oxygen Evolution Reaction Investigation on Pt(111) and Ir(111) Using Dynamic Electrochemical Impedance Spectroscopy in Acidic Medium
Authors: Scohy Marion , Dubau Laetitia , Maillard Frederic , Sibert Eric , Sunde Svein
Published: February 2020

Polymer electrolyte membrane water electrolyzers (PEMWE) are promising devices for energy conversion from electricity to chemistry. They are able to deal with important and fast changes in energy production. At the cathode compartment, the hydrogen evolution reaction occurs without kinetic limitation and practically reversibly. Nonetheless, the oxygen evolution reaction (OER) which is the anodic reaction remains a scientific challenge due to kinetic limitations and stability issues. Iridium is currently the best compromise between activity and stability [1]. However, it still undergoes degradation in the harsh oxidative and acidic operating conditions of a PEMWE [2].

The development of optimized OER catalysts is an essential step to practically implement PEMWE. A better understanding of structural effects on the catalysts activity and stability is needed. This study focuses on well-defined electrocatalysts at an atomic scale. The Ir(111) surface was characterized before and after electrooxidation and OER thanks to different electrochemical methods. A Pt(111) single-crystal, widely studied in the literature [3-4], was characterized in the same way and used as a reference. Above 1.4 vs. RHE and 1.3V vs. RHE, respectively for Pt(111) and Ir(111), the initial clean surface undergoes irreversible strucutral changes, related to the formation of defects and leading to an improvement of the oxygen evolution activity. Although classical electrochemical impedance spectroscopy (EIS) is a valuable technique when applied to stable and reversible systems, it fails with irreversible ones. Therefore, we used dynamic electrochemical impedance spectroscopy (DEIS). One can see (fig. 1) that the two methods give the same result in the reversible hydrogen adsorption area (fig.1a) while they differ for oxide formation (fig.1b) and OER (fig.1c). By analyzing the whole set of DEIS spectra, we are able to provide details on mechanism parameters for oxide formation and OER.

References

[1] Aricò, A. S., et al. (2012). "Polymer electrolyte membrane water electrolysis: status of technologies and potential applications in combination with renewable power sources." Journal of Applied Electrochemistry 43(2): 107-118.

[2] Cherevko, S., et al. (2014). "Dissolution of Noble Metals during Oxygen Evolution in Acidic Media." ChemCatChem 6(8): 2219-2223.

[3] CONWAY, B. E. (1995). "ELECTROCHEMICAL OXIDE FILM FORMATION AT NOBLE METALS AS A SURFACE-CHEMICAL PROCESS." Progress in Surface Science 49(4): 331-452.

[4] Drnec, J., et al. (2017). "Initial stages of Pt(111) electrooxidation: dynamic and structural studies by surface X-ray diffraction." Electrochimica Acta 224: 220-227.

Figure 1
Ordered Pt Nanopattern Catalysts through Self-Assembled Block Copolymer Template
Authors: Gan Yuan , Yan Changfeng , Wang Zhida
Published: February 2020

Patterning of metallic nanoparticles (NPs) via BC micelles plays an important role in the manufacture of conductive integrated devices. BCs containing a metal-binding block of poly(vinylpyridine) (P2VP or P4VP) can be used as a direct chemical reagent to coordinate to or to be protonated by metal ions and compounds such as chloroplatinic acid (H2PtCl6) or auric acid (HAuCl4). In this work, Platinum nanoparticles (Pt NPs) were synthesized by dip-coated technique on titanium wafers. The dip-coating withdrawal rate and concentration of H2PtCl6 precursor had been investigated as two of most important factors on the morphology of Pt-NP arrays. The result shows that diameter of nanodots decreases with the increase of withdrawal rate. The initial ECSA and durability of the Pt/Ti catalysts, with an initial ECSA of 106.5 m2.g-1 and a nearly zero particle-aggregation during 3000-cycle CV, can be controlled through particle size and spacing.
Understanding and Tailoring the Performance of Transition Metal Oxides for the Oxygen Evolution Reaction
Authors: Tripkovic Vladimir , Hansen Heine A. , Vegge Tejs
Published: February 2020

The oxygen evolution reaction (OER) is the bottleneck in direct solar and electrocatalytic water splitting cells, and rechargeable aqueous metal-air batteries. Improving the cost-efficiency of these devices requires development of efficient and cheap oxygen evolving catalysts. A good catalyst material should fulfil several important criteria: the composition and structure should be stable at conditions of interest, it should be able to conduct electrons from the active site, and it should be sufficiently active to catalyze water oxidation to oxygen.

We explore three different oxide classes comprising 1st row transition metals 1) pristine and doped Co and Ni oxyhydroxides (ox-hy), 2) pristine and doped perovskite oxides ABO3 (A is the earth-alkali or lanthanide metal and B the 1st row transition metal) and 3) pristine and doped αMnO2 as catalysts for the oxygen evolution reaction in neutral to alkaline pH. The emphasis in the analyses is placed on the three most important performance parameters: structural stability, catalytic activity and electronic conductivity.

For the ox-hy class we systematically investigate the influence of the nano-scale structure going from 3D catalysts to 2D nanosheets; we examine different edge and terrace terminations, as well as the effect of all stable metal dopants on the performance at pertinent potentials. We identify Fe doped Co, and V, Fe, Ru, Ir and Rh doped Ni ox-hys, as the best catalyst materials, out of which Rh doped Ni ox-hys exhibits the highest activity. Furthermore, we find that the electronic conductivity changes with the nature and valence of the dopant atom, which in turn depends on potential.

For the perovskite oxides, we identify Fe4+, Co3+(IS), Ni3+ and Mn3+/Mn4+ pairs as electronically conductive species and distinguish among three different conduction types: intrinsic conductance (Fe4+, Co3+(IS) and Ni3+), electron polaron hoping in Mn compounds with mixed valences and conduction via oxygen 2p and metal 3d holes in the valence band.

We investigate whether the performance of αMnO2, which according to many studies is the most active MnO2 polymorph, can be further improved by means of doping. Through a systematic approach we identify Pd doped αMnO2 to be a stable and highly active catalyst for the oxygen evolution reaction.

This work was supported by the Horizon 2020 framework, grant number 646186.
Crosslinked Ionomer Films for Use As Magnesium-Sulfur Battery Cathode Coatings
Authors: Ford Hunter O. , Merrill Laura C. , Schaefer Jennifer L.
Published: February 2020

The development of new rechargeable battery systems employing novel chemistries is imperative to meet the increasing energy storage demands of emerging technologies. Magnesium-sulfur (Mg-S) is one promising chemistry for moving beyond lithium-ion, owing to the widespread abundance of both Mg and S and the high theoretical energy density of the Mg-S couple. However, it is well known that similar to other batteries with sulfur cathodes, the Mg-S system suffers dramatic capacity fade as a result of the polysulfide shuttle effect. A series of model crosslinked polymer networks are herein investigated for use as cathode coatings to eliminate or restrict the polysulfide shuttle. Understanding the mechanisms governing ion transport in these systems is critical for engineering materials that balance the need to transport magnesium but restrict polysulfide crossover. The effects of dielectric constant, electrostatic interactions, and steric configurations on magnesium and polysulfide ion transport through the model networks are examined in detail. X-ray scattering, diffusion experiments, and conductivity measurements are used in tandem to relate structural and transport properties of the polymer networks. In general, we find that some characteristics that facilitate magnesium ion conduction likewise facilitate polysulfide crossover. By analyzing the model networks both ex-situ and implemented as cathode coatings, correlations between fundamental materials properties of the ionic polymer networks and performance enhancement of Mg-S cells containing coated cathodes are made. These insights are used to propose design rules for effective sulfur cathode coatings.
Magnesium-Ion Cathode Materials Based on the Barite Structure
Authors: Hawthorne Krista L , Liao Chen , Lau Ka-Cheong , Proffit Danielle L. , Vaughey John T.
Published: February 2020

Lithium-ion batteries have been a mainstay of the consumer electronics industries for nearly 25 years. Unlike many older energy storage systems, lithium-ion does not describe a specific chemistry but a family of chemistries and a mechanism of operation. As a result numerous types of materials are under the umbrella of lithium-ion batteries that can be modified and developed to meet a variety of end-user goals. Looking beyond-lithium ion, the landscape is less understood and explored.

One promising area of Beyond-Lithium-Ion research has been magnesium-based systems. In this presentation we will explore the relationship between materials structure, electrolyte, and synthesis. Specific examples will be drawn from the multivalent work done by JCESR, an Energy Innovation Hub under the Department of Energy’s Office of Science. Insertion cathode materials including layered molybdates, vanadates, and related materials will be compared and contrasted to other potential host frameworks to assess limits in electrochemical performance that are driven by interfacial structure and electrolyte interactions1-5.

Figure 1. Characterization of the as made Ca ion-exchanged NaxCoO2 samples with different calcium contents. The figure shows the normalized Ca XANES, indicated by solid lines, showing the sensitivity of this method to the concentration of calcium in the layered cobaltate. CaCO3 (orange, short dash) is included for comparison since Ca0.6CoO2 is expected to have CaCO3 impurities. Ca(PF6)2 (pink, long dash) is included to show that the discriminating features are well placed as compared to the CaxCoO2 spectrum. Each spectrum is offset by an additional -0.5 on the y axis, with the exception of CaCO3 and Ca(PF6)2. Composition was measured by EDS. (from ref 5).

References

Bucur, C.B., Gregory, T, A. G. Oliver, Muldoon, J., Phys. Chem. Lett.
6, 3578−3591 (2015).

Amatucci, G., Badway, F., Singhal, A., Beaudoin, B., Skandan, G., Bowmer, T., Plitz, I., Pereira, N., Chapman, T., Jaworski, R., Journal of the Electrochemical Society, 148 A940-A950 (2001).

Ling,C., Chen, J., Mizuno, F., Phys. Chem. C, 117, 21158−21165 (2013).

Mohtadi, R., Mizuno, F., Beilstein J. Nanotechnol.
5
, 1291–1311(2014).

Proffit, D. L., Fister, T.T., Kim, S., Pan, B., Liao, C., Vaughey J., Journal of the Electrochemical Society, 163 (13) A2508-A2514 (2016).

Figure 1
Local Variation in Microstructure Causes Heterogeneity in the Conductivity of Commercial Lithium-Ion Cathode Films
Authors: Vogel John E , Hardy Emilee E , Crawford Sean , Mazzeo Brian A , Wheeler Dean R.
Published: February 2020

Lithium-Ion battery success can be defined by a series of measureable characteristics. Two important characteristics that have been difficult to fully explore are the ionic [1] and electronic tortuosity. Micro-N-line probes were previously developed [2][3] in order to accurately measure electronic thin-film conductivity on a micro-scale.

Multiple iterations of the probe have been produced, tested and verified. In order to meet the final goal of a probe that could be implemented in any laboratory or production line, changes to the substrate, probe, and sizing were necessary. The final design also required substantial changes to methodology as well as the conductivity inversion calculations. The new probe is produced on a flexible substrate for a fraction of the original production cost and a fraction of the original production time.

Here we show that the new probe has been used to test battery films and measure battery film heterogeneity on a mm scale (See Figure 1). COMSOL modeling of the battery under testing conditions shows minimal influence by the battery current collector on measurements; this allows for non-destructive measurements of standard battery films.

The probe shows key advances in robustness and flexibility which allows for implementation on a rolling production line. New affordable stages have been developed to produce reliable measurements. High and low conductivity locations are still able to be found which is consistent with previous results.

Acknowledgements

This research is supported by the US Department of Energy through the Advanced Battery Material Research (BMR) Program.

References

[1] S.W. Peterson and D.R. Wheeler, "Direct Measurements of effective electronic transport in porous li-ion electrodes", Journal of the Electrochemical Society, vol. 161, no. 14, A2175-A2181, 2014

[2] B.J. Lanterman, A.A. Riet, N.S. Gates, J.D. Flygare, A.D. Cutler, J.E. Vogel, D.R. Wheeler, and B.A. Mazzeo, "Micro-four-line probe to measure electronic conductivity and contact resistance of thin-film battery electrodes", Journal of the Electrochemical Society, vol. 162, no. 10, A2145-A2151, 2015

[3] M.M. Forouzan, C.-W. Chao, D. Bustamante, B.A. Mazzeo, and D.R. Wheeler, "Experiment and simulation of the fabrication process of lithium-ion battery cathodes for determining microstructure and mechanical properties", Journal of Power Sources, vol. 312, pp. 172-183, 2016

Figure 1: Figure (a) showing the new probe, (b) the COMSOL model of the new probe, and (c) the results of a simple electrode conductivity mapping experiment run on a standard NMC TODA523 electrode.

Figure 1
Transport and Electrochemical Dynamics in the Li-S Battery Electrolyte
Authors: Mistry Aashutosh N , Mukherjee Partha P.
Published: February 2020

Lithium-sulfur chemistry is a promising candidate beyond intercalation-based Li-ion batteries. In addition to an order of magnitude higher theoretical capacity, it provides some unique advantages such as being free of sluggish intercalation dynamics. On the flip side, the electrolyte phase description in such cells is quite intricate, and poorly understood till date. The identity of ionic charge carriers in the electrolyte phase changes upon pore-scale reactions. This alters the intrinsic ionic transport characteristics as the cell operation progresses. Interestingly this evolution of electrolyte phase exhibits hysteresis as reaction pathway differs for consecutive charge and discharge operations. Additional complexities arise from electrode microstructural evolution, which modifies the effectiveness of transport through porous electrodes. Such porosity changes introduce electrolyte level variations in the porous electrode. This flow is in response to pressure gradients in the electrolyte phase, and brings about further complexation. Current work explores the effects of such diverse electrolyte limitations and how they correlate to physicochemical behavior, microstructural and operational specifications of these cells.
(Invited) A New Type of Ni-Doped LiCoO2 with Enhanced Structural and Electrochemical Reversibility at High Voltage
Authors: Cho Woongrae , Cho Jaephil
Published: February 2020

Li1-xCoO2 is the first commercialized and the most common active material in Li-ion cathodes, owing to its stable electrochemical performance in terms of cycle and rate capability. However, despite its high theoretical energy density (1070 Wh kg-1), LiCoO2 has only achieved relatively low gravimetric energy density (< 630 Wh kg-1) due to an irreversible phase transition after Li extraction of more than x = 0.6 (into Li1-xCoO2). On the other hand, Ni-rich layered materials (LiNixM1-xO2, M = Co or Mn, x > 0.6) have higher gravimetric energy density (> 720 Wh kg-1) than LiCoO2, in spite of the same Rm structure and similar theoretical capacity, because of their reversible Li extraction up to more than x = 0.7. However, the Ni-rich materials still have similar volumetric energy densities (< 2300 Wh L-1) with LiCoO2, due to their lower electrode densities (< 3.0 g cm-3, compared to < 4.0 g cm-3 for LiCoO2). Therefore, a better way to achieve high volumetric energy density is increasing the electrochemical reversibility of LiCoO2 to levels comparable to that of Ni-rich materials.

Previous studies about layered-structured materials mainly focused on improving their electrochemical reversibility, but fundamental investigation regarding different electrochemical reversibility between LiCoO2 and Ni-rich material was not a main issue and related studies are conducted base upon only chemical de-lithiation and simulation data.

Herein, we directly examine the two materials' structural changes and different irreversible deterioration mechanisms during cycling. In-situ X-ray diffraction patterns and theoretical calculation suggest that the phase transition of LiCoO2 from O3 oxygen stacking to O1 or O2 oxygen stacking is caused by increased oxygen-oxygen electrostatic repulsion during the charge process. Furthermore, we investigated a critical role of cations in lithium sites in layered-structured cathode materials. In case of Ni-rich materials, migration of Ni ions into the Li vacancies in Ni-rich materials during charge, a process called as 'cation mixing', screens the oxygen-oxygen repulsion that arises from lithium vacancies. This suppresses lattice parameter expansion along the c-axis, and therefore delays the phase transition although the cation mixing is cause of structural failure in Ni-rich material upon further Li extraction. As a result, LiCoO2 with 10% nickel-doped (LiCo0.9Ni0.1O2) displayed much enhanced electrochemical reversibility, which was increased by 0.1 mol lithium ion extraction with maintaining its electrode density of ~ 4.0 g cm-3.
M-N-Doped Carbon Nanofibers Modified Separators for Lithium-Sulfur Batteries
Authors: Song Xiong , Chen Guoping , Wang Suqing , Wang Haihui
Published: February 2020

A novel lightweight, multi-functional layer comprised of 1D porous metal-embedded nitrogen-doped carbon nanofibers (M-N-C) and 2D graphene sheets is introduced to modify a commercial polyolefin separator for using in lithium-sulfur batteries. Benefiting from the high electrical conductivity and strong lithium polysulfides (LiPSs) chemical adsorption ability of M-N-C, the porous intercalation-structured modified layer exhibits excellent ability to suppress LiPSs shuttling while maintaining high lithium-ion transport, and the modified layer functions as a highly conductive upper current collector to reutilize active sulfur species. The cell assembled with the modified multifunctional separator shows a high rate capability and excellent cycling stability. These exciting results indicate that this multifunctional membrane could be a promising separator candidate for Li-S batteries.
Electrocatalysis of Polysulfide Conversion By Sulfur-Deficient MoS2 Nanoflakes for Lithium-Sulfur Batteries
Authors: Lin Haibin , Lee Jim Yang
Published: February 2020

Lithium-sulfur batteries are promising next-generation energy storage devices due to their high energy density and low material cost. The efficient conversion of lithium polysulfides to lithium sulfide (during discharge) and to sulfur (during recharge) is a performance-determining factor for the lithium-sulfur batteries. Here we show that MoS2-x/reduced graphene oxide (MoS2-x/rGO) can be used to catalyze the polysulfide reactions to improve the battery performance. It was confirmed, through the microstructural characterizations of the materials, that sulfur deficiencies in the surface participated in the polysulfide reactions and significantly enhanced the polysulfide conversion kinetics. The fast conversion of soluble polysulfides decreased their accumulation in the sulfur cathode and their loss from the cathode by diffusion. Hence in the presence of a small amount of MoS2-x/rGO (4 wt% of the cathode mass), the sulfur cathode improved its high rate (8 C) performance from a capacity of 161.1 mAh g-1 to 826.5 mAh g-1. In addition, MoS2-x/rGO also raised the cycle stability of the sulfur cathode from a capacity fade rate of 0.373% per cycle (over 150 cycles) to 0.083% per cycle (over 600 cycles) at the typical 0.5 C rate. These results provide the direct experimental evidence for the catalytic role of MoS2-x/rGO in promoting the polysulfide conversion kinetics in the sulfur cathode.
Strategies for Overcoming Irreversible Lithium-Ion Losses in Silicon-Based Anodes
Authors: Song Farren Botao , Biswal Sibani Lisa
Published: February 2020

Silicon-based anodes are a promising replacement for carbon-based anodes for lithium-ion batteries due to their high specific capacity (3759 mAh/g). However, capacity fading due to irreversible Li+ losses prevent successful pairing up with commercially available cathode materials for a full-cell batteries. It is thought that the continuous reformation of the solid electrolyte interphase and parasitic reactions consume lithium-ions stored in cathode. Here, we will present two different pre-conditioning methods and various cycling strategies (full-potential and constant charge capacity at 1000 mAh/g) with high-surface area porous silicon-based composite anodes with lithium iron phosphate cathodes. Our experiments will demonstrate new methods and strategies for overcoming irreversible losses in silicon-based anode materials.
Jahn-Teller Distortion and Disproportionation in Spinel Lithium Manganese Oxides from First Principles
Authors: Voros Marton , Garcia Juan , Warburton Robert , Iddir Hakim , Greeley Jeffrey , Curtiss Larry A
Published: February 2020

Spinel lithium manganese oxide (LMO) is a promising cathode material for Li-ion batteries. Dissolution of manganese from LMO into the electrolyte, however, limits its cycle life. The widely accepted mechanism of dissolution requires charge disproportionation of Mn(III), but the atomistic details of such processes have remained elusive. The dissolution has also been loosely correlated with the Jahn-Teller activity of Mn, especially when LMO is over-lithiated. Using first-principles simulations, we provide insights into the mechanism of both Jahn-Teller activity and disproportionation and discuss possible connections between the two.
Structural Evolution and Electrochemical Properties of O3-Type Layered Oxide with a Quaternary Transition Metal Composition
Authors: Kim Jae Chul , Kwon Deok-Hwang , Shi Tan , Wang Jingyang , Kim Haegyeom , Bianchini Matteo , Ceder Gerbrand
Published: February 2020

To meet growing need for large-scale energy storage, rechargeable batteries that reversibly cycle sodium ions are an attractive alternative to the Li-based technology. In particular, Na-intercalating oxides favorably form energy-dense layered structures with almost all transition metals, allowing a wide selection of redox centers to obtain desirable electrochemical activities. However, desodiation in the layered materials is often limited by structural instability due to transition metal migration at high voltage. To address this issue, we formulate a quaternary-mixed transition metal system with the O3-type layered structure.

We propose Ti as a structural stabilizer and report a composition of NaTi0.25Fe0.25Co0.25Ni0.25O2 in this work. Synthesized by a solid-state reaction, the compound obtained is phase-pure with the R-3m symmetry. X-ray absorption spectroscopy reveals that transition metal oxidation states are Ti4+, Fe3+, Co3+, and Ni2+, suggesting that Ti remains electrochemically inert while others are redox-active. Our results highlight promising electrochemical performance of the material; 504 Wh kg-1 at C/20 and 200 Wh kg-1 at 30C at room temperature. According to in situ X-ray diffraction, the structural evolution upon desodiation differs from that upon resodiation. Interestingly, compared with the pristine O3 structure, we find that the discharged structure at 2 V after cycle is unchanged, leading to respectable cyclability. We will discuss the possible origin of this path-dependency of desodiated structures and its implication on electrochemical properties. Also, perspectives on the multi-transition metal system for layered cathode materials will be provided in this talk.
(Invited) Charge Compensation By Cationic/Anionic Redox for High-Capacity Positive Electrode Materials
Authors: Yabuuchi Naoaki
Published: February 2020

In the past decade, lithium-enriched compounds, Li2MeO3 (Me = Mn4+, Ru4+ etc.), have been extensively studied for high-capacity positive electrode materials of lithium batteries. Although the origin of high reversible capacities was a debatable subject for a long time, recently it has been evidenced that charge compensation is partly achieved by solid-state redox of non-metal anions, i.e., oxide ions (anionic redox),[1] coupled with solid-state redox of transition metal ions (cationic redox), which is the basic theory used for classical lithium/sodium insertion materials. Competition between cationic and anionic redox reactions is often evidenced for the lithium-enriched materials because the energy level of oxygen 2p band is lowered by the presence of excess lithium ions with high ionic characters in the crystal lattice. Reversibility of anionic redox reactions is also influenced by ionic and covalent characters for chemical bonds of transition metal ions.[2, 3] In contrast, when the energy of metal 3d band is low enough than that of oxygen 2p, pure cationic redox is realized even for the lithium-excess system.[4, 5] Moreover, this concept is further extended to sodium battery applications.[6] From these findings, we discuss the stabilization and destabilization mechanisms and material design strategy with the concept of cationic and anionic redox reactions to develop new high-capacity lithium/sodium insertion materials for battery applications.

References

[1] M. Sathiya et al, and J.-M. Tarascon, Nature Materials, 12, 827 (2013).

[2] N. Yabuuchi et al., PNAS, 112, 7650 (2015).

[3] N. Yabuuchi et al., Nature Communications, 7, 13814 (2016).

[4] S. Hoshino, et al., and N. Yabuuchi, ACS Energy Letters, 2, 733 (2017).

[5] M. Nakajima and N. Yabuuchi, Chemistry of Materials, 29, 6927 (2017).

[6] K. Sato et al., and N. Yabuuchi., Chemistry of Materials, 29, 5043 (2017).
Selenium Impregnated Monolithic Carbons as Free-Standing Cathodes for High Volumetric Energy Lithium and Sodium Metal Batteries
Authors: Mitlin David , Ding Jia
Published: February 2020

Energy density (energy per volume) is a key consideration for portable, automotive and stationary battery applications. We created selenium (Se) lithium and sodium metal cathodes that are monolithic and free-standing, and with record Se loading of 70 wt%. The carbon host is derived from nanocellulose, an abundant and sustainable forestry product. The composite is extremely dense (2.37 g cm-3), enabling theoretical volumetric capacity of 1120 mAh cm-3. Such architecture is fully distinct from previous Se – carbon nano or micropowders, intrinsically offering up to 2X higher energy density. For Li storage, the cathode delivered reversible capacity of 1028 mAh cm-3 (620 mAh g-1) and 82% retention over 300 cycles. For Na storage 848 mAh cm-3 (511 mAh g-1) was obtained with 98% retention after 150 cycles. The electrodes yield superb volumetric energy densities, being 1727 Wh L-1 for Li-Se and 980 Wh L-1 for Na-Se normalized by total composite mass and volume. Despite the low surface area, over 60% capacity is maintained as the current density is increased from 0.1 to 2 C (30 min charge) with Li or Na. Remarkably, the electrochemical kinetics with Li and Na are comparable, including the transition from interfacial to diffusional control.
(A03 Best Poster Winner) Electrochemical and Microstructural Analysis of Cu6Sn5 Alloy Electrodes
Authors: Juarez-Robles Daniel , Gonzalez-Malabet Hernando J. , Ausderau Logan , Xiao Xianghui , Nelson George J. , Mukherjee Partha P.
Published: February 2020

In recent years, copper-tin has risen as one of the most promising anode materials. It possesses a higher energy density than the conventional graphitic anode electrodes. And, the binary copper-tin alloy seems to mitigate the drastic volume changes, exhibited by other high capacity alloy electrodes (e.g., silicon, tin), during cycling. In order to take the next step, and implement this material in commercial applications (e.g., transport and portable electronics), it’s necessary to have a comprehensive understanding of its electrochemical performance.

In a conventional lithium-ion cell, the electrode consists of a porous intricate composite of three main components: active material, conductive additive and a polymeric binder. Electrochemical performance of these electrodes depends upon not only on the components but also on the electrode microstructure defined by the particle size, electrode thickness, porosity, and composition. The electrode microstructure also evolves according to the cycling condition; hence, the cell performance is affected by these changes.

In the present work, the microstructural-electrochemical interaction on Cu6Sn5 composite electrodes is studied. The electrode microstructure is modified by varying the composition and the drying temperature. The effect of the voltage window and its correlation with the copper expulsion phenomena is also analyzed. The former is accomplished through charge/discharge cycling of Cu6Sn5 half cells. Morphological changes are studied by removing the electrode from the cell and analyzing it using micrographic (SEM) techniques. Results will show how the mechanical degradation of the electrode impact the long term cycling performance.
Highly Defective Hard Carbon Anode for Na-Ion Batteries By Microwave Heating
Authors: Li Zhifei , Chen Yicong , Jian Zelang , Jiang Heng , Razink Joshua , Stickle William F. , Neuefeind Joerg , Ji Xiulei
Published: February 2020

Hard carbon has been considered as one of the most promising anode materials for Na-ion batteries (NIBs). As low cost is one of the major advantages of NIBs over Li-ion batteries (LIBs), the relative high cost of hard carbon has been the bottleneck for the commercialization of NIBs. In addition, a large portion of the capacity for conventional hard carbon is contributed from the low-voltage plateau part, which increases the risk of dendrite formation, thus causing a safety concern. Guided by the mechanism of Na-ion storage in hard carbon we proposed, where the sloping capacity is correlated to the structural defects, we design a new hard carbon by a microwave treatment on a low-temperature annealed hard carbon. The microwave treatment enhances its conductivity by forming a heterogeneous carbon structure, where there are highly ordered large nanodomains formed under microwave as conducting conduits and importantly during the short microwave treatment, i.e., 6 seconds, the carbon structure still retains its high extent of structural defects, as demonstrated by neutron scattering and pair distribution function results. Such a structure exhibits short plateau Na-ion storage but high sloping capacity, where surprisingly the Na-ion diffusivity in the microwave-treated carbon is higher than conventional hard carbon formed by high temperature annealing. Notably, the microwave treatment is much energy efficient in preparation of hard carbon than conventional annealing. This work supports our prior proposed mechanism and points out a new direction for hard carbon preparation as NIB anodes.
PEDOT:PSS Electroactive Binder for Silicon Nanoparticles in Li-Ion Battery Applications
Authors: Mery Adrien , Bernard Pierre , Chandesris Marion , Haon Cédric , Alper John Paul , Herlin Nathalie , Duclairoir Florence , Sadki Said
Published: February 2020

Silicon is for many years a coveted Li-ion battery material by the scientific community. This material exhibits a high theoretical specific capacity of 3579 mAh/g (10 times higher than graphite material) making it very promising for Li-ion negative electrodes. However, two main problems appear with silicon electrode during cycling, its structural degradation (leading to a loss of contact between silicon particles) and the instability of the Solid Electrolyte Interphase (SEI), mainly due to the huge volume expansion of Silicon particles during cycling (around 300 %). Different ways have been studied to tackle these problems, including the nanostructuration of Si particles to reduce the stress undergone during charge/discharge cycles. More recently, the use of conducting polymers as binders inside the electrode formulation was studied in place of classical binders like PVDF or CMC. The use of a conducting polymer as an alternative to traditional insulating binder in combination with conductive additive (carbon black, graphene…) allows to play the role of both binder and electronical conductor. Consequently, it leads to reduce space and interfacial parameters by the elimination of these inorganic (and non-active) conductive materials in the electrode formulation. The conducting polymer used in this work is the PEDOT:PSS. This polymer is well known for its good chemical and mechanical stability and its potential high electrical conductivity (10-2 to 103 S/cm). It is mainly studied in the domain of photovoltaic and its use in the battery domain for electrode formulations begins to appear. The results of this study will be devoted to the evaluation of Li-ion negative electrode containing Silicon (or Silicon@carbon composite) nanoparticles with PEDOT:PSS binder. Si and Si@C nanoparticles are synthesized by laser pyrolysis. This process offers the possibility to decrease the size of the particles and to coat the silicon by a carbon shell, all in one step of synthesis. Electrode formulations containing the active material (Si or Si@C) and the PEDOT: PSS binder (without other additives) are coated on a Cu current collector to perform electrochemical tests. Cyclic voltammetry, Electrochemical Impedance Spectroscopy (EIS) and galvanostatic cycling were performed in half-cells containing the Si (or Si@C)/PEDOT:PSS electrode versus a lithium foil. Specific capacities up to 1000-1500 mAh/g and stable over more than a hundred cycles of charge/discharge were achieved. These very encouraging results highlight the potential of PEDOT:PSS as electroactive binder for silicon electrodes in Li-ion batteries.

Figure 1