bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural Transformations in High Capacity Li2Cu0.5Ni0.5O2 Cathodes
Authors: Ruther Rose Emily , Pandian Amaresh Samuthira , Yan Pengfei , Weker Johanna Nelson , Wang Chongmin , Nanda Jagjit 
Published: February 2020

Cathode chemistries with more than one lithium per transition metal (multi-lithium cathodes) are one approach for increasing the energy density of lithium-ion cells. Examples include lithium-rich NMCs (xLi2MnO3·(1−x)LiMO2 where M=Mn, Ni, Co), anti-fluorite type oxides, and several polyanionic compounds. Many of these cathodes have very high theoretical capacities, but none has proven practical for commercial cells. These materials generally undergo structural transformations, often accompanied by oxygen loss, which limit electrochemical reversibility. In this contribution, we present a thorough investigation of Li2Cu0.5Ni0.5O2, as a model system to understand the larger family of multi-lithium cathodes. Results from XRD, Raman spectroscopy, TEM, XANES, and gas evolution measurements follow the chemical, structural, and morphological changes that occur during electrochemical cycling. Our study broadly demonstrates the challenges associated with multi-lithium transition metal oxides, where there is close interplay between structure, transport, and oxygen loss that limits their use as high capacity cathodes for advanced lithium-ion systems.

Acknowledgement

Research has been supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy through the Advanced Battery Materials Research (BMR) Program. The authors acknowledge the support of Stanford Synchrotron Radiation Lightsource, a Directorate of SLAC National Accelerator Laboratory and an Office of Science User Facility operated for the U.S. Department of Energy Office of Science by Stanford University. X-ray diffraction was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. The TEM work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a DOE User Facility operated by Battelle for the DOE Office of Biological and Environmental Research. Pacific Northwest National Laboratory is operated for the DOE under Contract DE-AC06-76RLO 1830.
Scalable Template-Free Synthesis of Na2Ti3O7/Na2Ti6O13 Nanorods with Composition Tunable for Synergistic Performance in Sodium-Ion Batteries
Authors: Ho Ching-Kit , Li Chi-Ying Vanessa , Chan Kwong-Yu 
Published: February 2020

Sodium-ion batteries are regarded as one of the potential candidates to substitute lithium ion batteries in large-scale electric energy storage applications in the near future. Several forms of sodium titanates including Na2Ti3O7, Na2Ti6O13 and Na4Ti5O12 have recently been applied as anode in sodium ion batteries. Here, we present an energy-efficient solid-state synthesis, via the addition of carbon, to mass-produce a series of uniform and single-crystalline Na2Ti3O7/Na2Ti6O13 nanorods with tunable composition as anode materials for sodium-ion batteries.1 Due to the extra local heat generation and CO2/CO release from carbon oxidation, the carbon added in the synthesis provides an alternative low-temperature route for the Na2Ti3O7 formation at 450 °C, a reaction temperature much lower than that of conventional solid-state methods (750–1000 °C), and Na2CO3 is regenerated to be recycled in the synthesis. The high theoretical capacity of Na2Ti3O7 and low volume expansion of Na2Ti6O13 upon charge–discharge are synergistically exploited to achieve high electrochemical performance and stability.

References

1. Ho, C.-K.; Li, C.-Y. V.; Chan, K.-Y., Scalable Template-Free Synthesis of Na2Ti3O7/Na2Ti6O13 Nanorods with Composition Tunable for Synergistic Performance in Sodium-Ion Batteries. Industrial & Engineering Chemistry Research
2016,
55 (38), 10065-10072.

Acknowledgements

This project is financially supported by Research Grants Council of Hong Kong (GRF 17300014), HKU Small Project Funding (201409176115), HKU Strategic Research Theme on Clean Energy, and University Development Fund for Initiative for Clean Energy and Environment.

Figure 1
Investigating the Solid Electrolyte/Electrode Interfaces with X-Ray Absorption Spectroscopy
Authors: Vardar Gulin , Lu Qiyang , Wang Jiayue , Seibert Rachel , Lee Zhengrong , Chiang Yet-Ming , Terry Jeff , Yildiz Bilge 
Published: February 2020

Solid-state lithium-ion batteries hold great promise for obtaining higher energy densities but the power density is currently limited by the electrode-electrolyte interfaces. [1] The high resistances at SLIB interfaces are hypothesized to be due to chemical mixing, space charge formation, or secondary phase formation. [2,3] Although several secondary phases have been proposal theoretically, there is no experimental work studying the secondary phase formation as a function of temperature and applied voltage. Extended x-ray absorption fine structure spectroscopy (EXAFS) is a unique capability that allows us to probe the fine structure around the atoms at the electrode-electrolyte interface. Previous interface studies using XRD were not able to identify the secondary phases, either because secondary phases are small in amount or not crystalline. [3] Depth-sensitive x-ray absorption spectroscopy allows us to probe the changes in structure at the interface even if the secondary phases are not crystalline. This work studies the interface between Li7La3Zr2O12 (LLZO) and LiCoO2 (LCO).
[1] Cheng, L. et al.
Phys. Chem. Chem. Phys.
16, 18294–18300 (2014).
[2] Miara, L. J., et al. Chem. Mater.
27, 4040–4047 (2015).
[3] Park, K. et al.
Chem. Mater.
28, 8051–8059 (2016).
Imidazolium Based Dicationic Ionic Liquids As Electrolyte for Lithium Ion Batteries
Authors: Yen Yung-Che , Sun I-Wen 
Published: February 2020

Two imidazolium based dicationic ionic liquids(DILs), one with ether bridged structure, and the other with carbon chain bridged only(figure 1.), were synthesized and used as electrolyte for lithium ion battery, to evaluate whether the ether bridge structure would improve the performance of the lithium ion battery using ionic liquid electrolyte.
The half-cells were composed with LiFePO4cathode and lithium metal as anode. The mixed electrolyte included DIL, 0.5m lithium salt(LiTFSI), and sulfolane as additive to reduce viscosity and increasing conductivity. At high discharging rate, the specific capacity of the cell with ether bridged DIL showed significantly better performance than the other without ether bridged structure. For example, at 3C rate, the cell with [IMOI] mixed electrolyte showed a specific capacitor of 130mAh/g, but the one with [IMCI] had 88mAh/g only.

Figure 1
(Invited) Energetic Basis of Aqueous-Two-Phase Separation of Single Wall Carbon Nanotube Enantiomers
Authors: Jagota Anand 
Published: February 2020

Hybrids of single stranded DNA and single walled carbon nanotubes (SWCNTs) have proven very successful in selecting various chiralities and, recently, enantiomers of carbon nanotubes using aqueous two-phase (ATP) separation. This technique sorts objects based on small differences in hydration free energy, which is related to corresponding small differences in structure. Separation by handedness requires that a given ssDNA sequence adopt different structures on the two SWCNT enantiomers. In this talk we will discuss two aspects of the ATP separation process. Firstly, we study the physical basis of such selectivity using a coarse grained model to compute the energetics of ssDNA wrapped around an SWCNT. Our model suggests that difference by handedness of the SWCNT requires spontaneous twist of the ssDNA backbone. We also show that differences depend sensitively on the choice of DNA sequence. Secondly, we present a method by which measurements of partitioning by ATP can be used to rank quantitatively the solute solvation free energy.
(Invited) Carbon and Non-Carbon Nanomaterials for Sustainable Energy
Authors: Arepalli Sivaram 
Published: February 2020

For the last two decades, nanomaterials (NMs) have been successfully processed to impart superior mechanical, electrical and chemical properties to the materials used in innovative energy technologies that are critical for a sustainable energy future. It is important to know the possibilities as well as limitations of the use of NMs in providing sustainable solutions for issues of all forms of energy. The present talk will focus on the applications of carbon nanostructures (fullerenes, carbon nanotubes and graphene) and metal oxides (ZnO and TiO2) for light weight composites for terrestrial and space transportation [1,2]; energy production such as solar cells and fuel cells; energy storage using supercapacitors [3,4] and batteries; and energy transmission using quantum wires. Incorporation of NM nanocomposite structures are being pursued for applications of hydrogen storage [5] as well. Life cycle assessment of these NMs as well as the environmental, health and safety considerations will be discussed.
References:
1) Bismark Mensah, Han Gil Kim, Jong-Hwan Lee, Sivaram Arepalli and Changwoon Nah, “Carbon nanotube-reinforced elastomeric nanocomposites: a review”,
International Journal of Smart and Nano Materials
, Vol. 6, pp. 211-238 (2016).
2) Sivaram Arepalli and Padraig Maloney, “Engineered nanomaterials in aerospace”,
MRS Bulletin
Vol. 40, Issue 10, pp 804-811 (2015).
3) Srikrishna Pandey, Uday N. Maiti, Kowsalya Palanisamy, Pavel Nikolaev, and Sivaram Arepalli “Ultrasonicated Double Wall Carbon Nanotubes for Enhanced Electric Double Layer Capacitance”,
Appl. Phys. Lett.
Vol. 104, 233902 (2014).
4) Hae-Kyung Jeong, Meihua Jin, Eun Ju Ra, Kyeu Yoon Sheem, Sivaram Arepalli and Young Hee Lee, “Enhanced Electric Double Layer Capacitance of Graphite Oxide Intercalated by Poly Sodium 4-Styrensulfonate with High Cycle Stability”,
ACS Nano,
Vol. 4, pp. 1162-1166 (2010).
5) N. F. Attia, S. Arepalli, and K. E. Geckeler, “Polyaniline-inorganic nanotube composites: potential hydrogen storage materials at room temperature”,
International Journal of Hydrogen Energy, Vol. 38, pp. 9251-9262 (2013).

Figure 1
Effects of High-Porosity Conductive Foams on the Electrochemical Performance of Electrochemical Flow Capacitors
Authors: Akuzum Bilen , Agartan Lutfi , Hudson Deb , Gogotsi Yury , Kumbur E. Caglan 
Published: February 2020

Electrochemical flow capacitors (EFCs) are high-power, long-cycle life electrochemical systems that utilize flowable suspensions of activated carbon in certain electrolytes. The unique capability of flowable electrodes, which offers ease of scalability, has found many applications not only in the field of energy storage but also in capacitive deionization [1-2]. Currently, one major challenge that prohibits widespread adaptation of EFCs is the low electrical conductivity of the flowable electrodes when compared to the conductivity of the film electrodes. This is mainly caused by the high percentage of the electrolyte phase in the suspension, which is not electrically conductive. Hence, presence of readily formed electron percolation paths is of critical importance to ensure all particles have a viable electron transfer path towards the current collectors [3].
Here, we hypothesized that large pore size conductive foams such as reticulated vitreous carbons (RVCs) could offer a stationary electron transfer backbone for EFC cell fixtures and help decrease the inter-particle electron conduction distance in large channel thicknesses. Contrary to the common approach used in flowable electrochemical systems, currently proposed cell fixtures for flowable electrodes does not involve any high-surface area electrodes due to concerns over clogging and other flow related issues. Motivated by this, this study aims to investigate the feasibility of high-porosity conductive foams as three-dimensional current collectors in EFC cell fixtures. To accomplish this, flow cells containing RVCs selected from different porosities have been subjected to electrochemical testing under static and intermittent flow conditions. For the same electrode composition, a significant improvement in capacity (up to 2x) and in power density (up to 10x) has been observed with the utilization of conductive foams in the cell fixtures.

References

[1] B. Kastening, Berichte der Bunsengesellschaft für physikalische Chemie, 1988, 92, 11, 1399-1402.
[2] K. B. Hatzell, M. Boota and Y. Gogotsi, Chemical Society Reviews, 2015, 44, 8664-8687.
[3] C. R. Dennison, Y. Gogotsi, and E. C. Kumbur, Phys. Chem. Chem. Phsy., 2014, 16, 18241-18252.
Effect of Alumina Addition on Li6.75La2.75Ca.25Zr1.5Nb.5O12 Lithium Garnet
Authors: Limpert Matthew , Hitz Gregory T , McOwen Dennis W. , Atwater Terrill B , Wachsman Eric D. 
Published: February 2020

Lithium-conducting garnets are a promising solid state electrolyte in the cubic phase for lithium (Li) batteries because of their stability with lithium, wide electrochemical stability window, and high conductivity (~1 mS cm-1). Aluminum (Al) is a widely studied dopant due to its ability to stabilize the cubic phase because of the occurrence of unintentional doping from alumina crucibles used during synthesis. The quantity of aluminum in the material is critically important to sintering conditions and performance in both the bulk and at the grain boundaries. Al can diffuse into the structure of garnets and dope the Li site while removing three total Li for charge balance. Another possibility is the Al reacts with excess lithium or lithium that has left the structure during high temperature processing. This allows for a liquid phase to form, enabling better densification during sintering. In this work, the aluminum content in Li6.75La2.75Ca.25Zr1.5Nb.5O12 was varied and calcined in magnesia crucibles to limit Al contamination. One weight percent of alumina (0.1 moles) was added before the solid state reaction, producing a conductivity of 2.96 x 10-4 S cm-1 after sintering at 1100°C. Specifically in the sample with 0.1 Al added when sintered at 1100°C for 12 hours, the Al contributed to an increase in grain boundary conductivity to 1.96x10-3 S cm-1 and a decrease in total activation energy to 0.35 eV versus samples without any added aluminum. The varying Al content showed little variance in bulk conductivity over several sintering conditions, while showing a wide divergence of 2.72x10-3 S cm-1, in grain boundary conductivity. Possible explanations are discussed with structural, chemical, and EIS measurements detailed.
High Potential Organic Materials for Battery Applications
Authors: Guarr Thomas F. , Dumitrascu Adina , Prins Amber J. , Mortimer Nicholas , Henton Daniel R. 
Published: February 2020

Many organic heterocyclic compounds undergo reversible one-electron electrochemical oxidation. However, in order to function effectively as redox shuttles in lithium batteries, such materials must display such behavior at potentials exceeding 4.2 V vs Li/Li+, and designing compounds that meet this requirement yet remain stable in the cation radical form represents a significant challenge. We have developed two families of organic heterocycles suitable for battery applications; namely appropriately substituted carbazoles and phenothiazine 5,5-dioxides.
We will describe the synthesis and characterization of these compounds, along with preliminary results of testing in lithium ion batteries and redox flow batteries.

Figure 1
New Method for Monitoring Hydrogen Evolution of Magnesium Alloys Under Atmospheric Exposure
Authors: Strebl Michael , Virtanen Sannakaisa 
Published: February 2020

Magnesium (Mg) alloys are attractive lightweight materials for the automotive industry due to their low density and high specific strength [1]. However, widespread use of Mg alloy components is hindered by their corrosion properties. Full immersion conditions are frequently used to study the corrosion behavior, although Mg alloys are typically subjected to atmospheric corrosion environments in most applications. With a limited amount of electrolyte, the corrosion mechanism can be different [2]. For example, corrosion products that partly dissolve in a bulk electrolyte can remain at the surface and block active sites in the case of atmospheric conditions [3]. Effects of micro-galvanic coupling of secondary phases can be reduced with thin electrolyte films [4]. In addition, atmospheric concentrations of CO2 can influence the surface pH and change the composition of the corrosion products [3]. As a result, corrosion rates in atmospheric environments are smaller and cannot be directly compared to results obtained under immersion conditions.
The atmospheric corrosion progress is traditionally tracked gravimetrically by determining mass gain or mass loss of the samples after exposure. This work introduces a new method that makes it possible to monitor the real time atmospheric corrosion rate of Mg alloys during exposure. The idea is to measure the amount of hydrogen evolved during atmospheric corrosion. This is realized with an adaption of the gravimetric hydrogen collection method, originally developed by Curioni [5]. The change in buoyancy exerted by the evolved hydrogen gas can be accurately measured. Therefore, it is possible to monitor the instant atmospheric corrosion rate even at the initial stages of corrosion where mass loss measurements are difficult. Different exposure conditions like relative humidity, temperature or CO2 content can be studied. The possible contribution of the oxygen reduction reaction to the cathodic processes will be discussed.
References
[1] M. K. Kulekci, Int. J. Adv. Manuf. Technol., 39 851–865 (2008).
[2] M. Esmaily, D. B. Blücher, J. E. Svensson, M. Halvarsson, L. G. Johansson, Scr. Mater., 115 91–95 (2016).
[3] R. Lindstrom, L. G. Johansson, J. E. Svensson, Mater. Corros., 54 587–594 (2003).
[4] M. Jönsson, D. Persson, R. Gubner, J. Electrochem. Soc., 154 (11) C684–C691 (2007).
[5] M. Curioni, Electrochim. Acta, 120, 284-292 (2014).
Electrochemical Scanning Tunnelling Microscopy Study of Early Stages of Intergranular Corrosion of Copper
Authors: Marcus Philippe , Bettayeb Mohamed , Klein Lorena , Lapeire Linsey , Verbeken Kim , Maurice Vincent 
Published: February 2020

Electrochemical scanning tunnelling microscopy (EC-STM) was used to investigate in situ and locally the topographical alterations of copper surfaces under electrochemical control. The aim of this work was to better understand the early stages of intergranular corrosion and the relationship between local structure of grain boundaries emerging at the solid/liquid interface and corrosion properties. A prerequisite for this approach is the use of a high purity material, in order to exclude the segregation of impurities, such as sulphur, at grain boundaries, which would strongly affect the intergranular corrosion behaviour and prevent us from studying the intrinsic effect of grain boundary structure This was achieved in this work by using high purity cast electrolytic tough pitch (ETP-) Cu, cryogenic rolled and post-annealed at relatively low temperature (200°C). This process also produces a grain size compatible with the limited field of view of STM, as confirmed by electron back scatter diffraction (EBSD) analysis.
EC-STM data obtained in situ after a surface preparation producing oxide-free surfaces with emerging grain boundaries show that performing cycles of anodic dissolution in the absence of any surface oxide reveals a grain boundary structure-dependent corrosion behaviour. Localized attack is initiated at grain boundaries that can be assigned to either random-type boundaries or non-coherent coincidence site lattice (CSL) grain boundaries whereas, under the same conditions, coherent twin grain boundaries are not attacked. Direct coupling of EC-STM and EBSD, using a re-positioning procedure allowing the analysis of the same local surface area by both techniques, show that even for the corrosion resistant coherent twin grain boundaries, the intergranular corrosion behavior measured at the emergence of the grain boundaries at the solid/liquid interface is dependent on the local surface structure. Further combined EC-STM and EBSD analysis will be discussed to link grain boundary type, local surface structure and susceptibility to intergranular corrosion.
EIS Study on Detection of Corrosion Site of Reinforced Concrete By Two Sensing Electrodes
Authors: Hoshi Yoshinao , Koike Taisuke , Tokieda Hiroyuki , Shitanda Isao , Itagaki Masayuki 
Published: February 2020

A reinforced concrete has been used for the civil engineering and construction in the whole world. In order to obtain the real-time information of reinforced concrete, Dawson et al. 1) attempted to investigate the electrochemical behavior of reinforced concrete by an electrochemical impedance spectroscopy (EIS). John et al. 2) proposed the equivalent circuit to interpret the impedance spectrum of reinforced concrete. Though these methods can be applied to the investigation of conditions of reinforced concrete, an electrical connection of reinforced concrete to the measurement device is required. Keddam et al. 3) proposed the concept of floating electrode for contact-less electrochemical measurement of reinforced concrete. In this method, a four-electrode probe was set on the reinforcement, and the capacitive loop related to the double-layer capacitance at the cement-rebar interface was measured 3).
In the present study, a new method to detect the corrosion site of reinforced concrete was proposed by using two sensing electrodes. The sensing electrodes were placed on the surface of reinforced concrete as working and counter electrodes. The electrochemical impedance measurement was performed in this setup. The impedance related to the corrosion site of steel rebar in concrete with different cover thickness is measured by proposed method. In addition, the current and voltage distributions between sensing electrodes set on the concrete surface were discussed by a finite element method.
Reference:
1. J. L. Dawson, L. M. Callow, K. Hladky and J. A. Richardson, Corrossion/78, No-125(1978).
2. D. G. John, P. C. Searson, J. L. Dawson, Br Corros J, 16, 102-106 (1981).
3. M. Keddam, X. R. Nòvoa, V. Vivier, Corros. Sci., 51, 1795-1801 (2009).