Name: protocol of electrochemical test and characterization of aprotic li-o2 battery
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Description: Watch this Scientific Journal Video about Protocol of Electrochemical Test and Characterization of Aprotic Li-O2 Battery at JoVE.com

Research at Argonne National Laboratory was funded by U.S. Department of Energy, FreedomCAR and Vehicle Technologies Office. Use of the Advanced Photon Source and research carried out in the Electron Microscopy Center at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

Please consult all relevant Material Safety Data Sheets (MSDS) before use. Several of the chemicals used in these syntheses are acutely toxic and carcinogenic. Nanomaterials may have additional hazards compared to their bulk counterpart. Please use all appropriate safety practices when performing a nanocrystal reaction including the use of engineering controls (fume hood, glovebox) and personal protective equipment (safety glasses, gloves, lab coat, full length pants, closed-toe shoes). Portions of the following procedur...

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Considering the sensitivity of Li-O2 battery system to air, especially CO2 and moisture, lots of steps in the protocol are necessary in order to reduce the interferents and to avoid side reactions. For example, the Swagelok-type cell is assembled in a glovebox filled with Ar with O2 &#60; 0.5 ppm and H2O &#60; 0.5 ppm; and all the cathode materials, electrolyte solvent and salt, glass fiber, Swagelok parts, and the glass chambers are dried before assembly to reduce the moisture...

In 1996, Abraham and Jiang1 reported the first reversible non-aqueous Li-O2 battery consisting of a porous carbon cathode, an organic electrolyte, and a Li-metal anode. Since then, due to its extremely high theoretical energy density exceeding that of any other existing energy storage systems, the Li-O2 battery, which induces a current flow by the oxidation of lithium at the anode and the reduction of oxygen at the cathode (overall reaction Li+ + O2 + e- &#8596; Li2O2), has received significant interest recently.1-8
A cathode material with the following requirements would be able to cater for the needs of high performance of Li-O2 battery: (1) fast oxygen diffusion; (2) good electric and ionic conductivity; (3) high specific surface area; and (4) stability. Both the surface area and porosity of the cathode are critical for the electrochemical performance of Li-O2 batteries.9-12 The porous structure allows the deposition of solid discharge products generated from the reaction of Li cations with O2; and larger surface areas provide more active sites to accommodate electrocatalytic particles that accelerate the electrochemical reactions. Such electrocatalysts are added to the cathode material by certain deposition methods, which provide strong adhesion to the substrate and good control of the catalyst particles, with preservation of the original porous surface structure of the substrate.13-17 The as-prepared materials are tested in Swagelok-type cells as the cathode of aprotic Li-O2 battery. However, the performance of the cell not only depends on the nature of cathode materials, but also on the type of the aprotic electrolyte18-22 and Li-metal anode.23-26 More influences include the amount and concentration of the materials and the procedure used in the charge/discharge tests. Proper conditions and protocols would optimize and improve the overall performance of battery materials.
In addition to the results of the electrochemical test, the battery performance can be also evaluated by characterizing the pristine materials and the reaction products.27-33 Scanning electron microscopy (SEM) is used to investigate the surface microstructure of the cathode material and the morphology evolution of the discharge products. Transmission electron microscopy (TEM), X-ray absorption near edge structure (XANES), and X-ray photoelectron spectroscopy (XPS) can be used to determine the ultrastructure, chemical state, and component of elements, especially for that of catalyst nanoparticles. High-energy X-ray diffraction (XRD) is used for directly identifying the crystalline discharge products. Possible electrolyte decomposition can be determined by attenuated total reflection Fourier transform infrared (ATR-FTIR) and Raman spectra.
This article is a protocol that demonstrates a systematic and efficient arrangement of routine tests of the aprotic Li-O2 battery, including the preparation of battery materials and accessories, the electrochemical performance test, and characterization of pristine materials and reaction products. The detailed video protocol is intended to help new practitioners in the field avoid many common pitfalls associated with the performance testing and characterization of Li-O2 batteries.

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			<td height="25" style="height:25px;width:388px;">1-Methyl-2-pyrrolidinone (NMP), 99.5%</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:219px;">328634</td>
			<td style="width:63px;"></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Battery test system</td>
			<td style="width:160px;">MACCOR</td>
			<td colspan="2">Series 4000 Automated Test System</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Dimethyl carbonate (DMC), &#8805;99%</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:219px;">517127</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Ethyl alcohol, &#8805;99.5%</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:219px;">459844</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Formaldehyde solution, 37 wt. % in H2O</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:219px;">252549</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Graphitized Carbon black, &#62;99.95%</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:219px;">699632</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Iron(III) chloride (FeCl3), 97%</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:219px;">157740</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Kapton polyimide tubing</td>
			<td style="width:160px;">Cole-Parmer</td>
			<td>EW-95820-09</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Kapton polymide tape</td>
			<td style="width:160px;">Cole-Parmer</td>
			<td>EW-08277-80</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Kapton window film</td>
			<td style="width:160px;">SPEX Sample Prep</td>
			<td style="width:219px;">3511</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Lithium Chip (99.9% Lithium)</td>
			<td style="width:160px;">MTI Corporation</td>
			<td style="width:219px;">EQ-Lib-LiC25</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Lithium trifluoromethanesulfonate (LiCF3SO3)</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:219px;">481548</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Palladium hexafluoroacetylacetonate (Pd(hfac)2), 99.9%</td>
			<td style="width:160px;">Aldrich</td>
			<td style="width:219px;">401471</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Poly(vinylidene fluoride) (PVDF)</td>
			<td style="width:160px;">Aldrich</td>
			<td style="width:219px;">182702</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Potassium permanganate (KMnO4), &#8805;99.0%&#160;</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:219px;">223468</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Sodium hydroxide (NaOH), &#8805;97.0%</td>
			<td style="width:160px;">Sigma-Aldrich</td>
			<td style="width:219px;">221465</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Tetraethylene glycol dimethyl ether (TEGDME), &#8805;99%</td>
			<td style="width:160px;">Aldrich</td>
			<td style="width:219px;">172405</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:388px;">Toray 030 carbon paper</td>
			<td>ElectroChem Inc.</td>
			<td>590637</td>
			<td></td>
		</tr>
	</tbody>
</table>

protocol of electrochemical test and characterization of aprotic li-o2 battery

We demonstrate a method for electrochemical testing of an aprotic Li-O2 battery. An aprotic Li-O2 battery is made of a Li-metal anode, an aprotic electrolyte, and an O2-breathing cathode. The aprotic electrolyte is a solution of lithium salt with aprotic solvent; and porous carbon is commonly used as the cathode substrate. To improve the performance, an electrocatalyst is deposited onto the porous carbon substrate by certain deposition methods, such as atomic layer deposition (ALD) and wet-chemistry reaction. The as-prepared cathode materials are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray absorption near edge structure (XANES). A Swagelok-type cell, sealed in a glass chamber filled with pure O2, is used for the electrochemical test on a battery test system. The cells are tested under either capacity-controlled mode or voltage controlled mode. The reaction products are investigated by electron microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and Raman spectroscopy to study the possible pathway of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). This protocol demonstrates a systematic and efficient arrangement of routine tests of the aprotic Li-O2 battery, including the electrochemical test and characterization of battery materials.

Figure 1a shows the setup of the Swagelok-type cell of the Li-O2 battery test. A piece of lithium film is placed on a stainless steel rod at the anode end. The porous cathode is open to pure O2 through an aluminum tube. Glass fiber is used as a separator and an absorber of aprotic electrolyte; and Al-mesh is used as a current-collector. The whole Swagelok-type cell is sealed in a glass chamber filled with ultra-high purity oxygen. For in-depth study,...

Watch this Scientific Journal Video about Protocol of Electrochemical Test and Characterization of Aprotic Li-O2 Battery at JoVE.com

Protocol of Electrochemical Test and Characterization of Aprotic Li-O2 Battery

A protocol for the electrochemical testing of an aprotic Li-O2 battery with the preparation of electrodes and electrolytes and an introduction of the frequently used methods of characterization is presented here.

Protocol of Electrochemical Test and Characterization of Aprotic Li-O2 Battery

We demonstrate a method for electrochemical testing of an aprotic Li-O2 battery. An aprotic Li-O2 battery is made of a Li-metal anode, an aprotic ...

The overall goal of this procedure, is to demonstrate a systematic and efficient arrangement of routine tests of an aprotic lithium-oxygen battery, including an electro-chemical test and characterization of the battery materials. This protocol involves the study of the aprotic lithium-oxygen battery mechanism, and the development of battery materials, such as active materials or electro-catalysts, cathodes, aprotic electrolytes, and anode materials. The main advantage of this protocol is that involves components that can affect electro-chemical reactions in lithium-oxygen battery, such as nitrogen, carbon dioxide, and moisture from the atmosphere.It also reduces bi-products such as lithium hydroxide and lithium carbonate. To begin this procedure, mix previously prepared cathode material and polyvinylidene fluoride, or PVDF, in a four to one weight ratio. Add MP at about three times the weight of the mixture.Stir the mixture to make an even-textured slurry. Coat the slurry with a thickness around 100 micrometers onto carbon paper using a doctor blade. Then, dry the laminate overnight in a vacuum oven at 100 degrees Celsius.On the next day, punch the laminate into disks with a hole puncher and weigh them. For aprotic electrolyte preparation, dry lithium triflate overnight in a vacuum oven at 100 degrees Celsius. In an argon-filled glove box, prepare a one mole per liter solution of the dried lithium triflate in tetraethylene glycol dimethyl ether.Stir the solution with magnetic stirring until the salt is dissolved. To prepare the anode, punch lithium chips into disks with a hole puncher. Assemble the Swagelok Cell as shown here.Tighten the anode end and loosen the cathode end. Next, place one of the lithium disks on top of the stainless steel rod of the anode end. Place a glass fiber separator on the top of the lithium metal anode.Add five to seven drops of electrolyte to fully wet the glass fiber separator. Then, gently press the separator to remove bubbles. Following this, place a piece of cathode on the top of of the wetted separator with the active material facing the anode.Cover the cathode with a piece of aluminum mesh. Press the layers with the aluminum tube, and tighten the cathode end. Seal the whole Swagelok Cell in a glass chamber and fix the chamber with a clamp.After removing the cell from the glove box, connect the glass chamber to an ultrahigh purity oxygen tank. Purge the chamber with continuous oxygen flow at one atmosphere for 30 minutes. At this point, be sure the thermostat is set to 25 degrees Celsius.Place the cell and electrodes into the thermostat and fix them, then clip the cathode and anode on the glass chamber with the corresponding electronic clips. Next, open the operating software of the battery test system and select the Channel connected with the cable. Set the Discharge Cutoff Voltage to 2.2 volts for the discharge test.Set the Discharge Charge Step Time to 10 hours for the capacity-controlled cycling test. Then, set the Discharge Cutoff Voltage to 2.2 volts, and the Charge Cutoff Voltage to 4.5 volts for the voltage-controlled cycling test. Following this, run the procedure by clicking the run button on the software interface.Once the run is complete, disassemble the cell in the glove box. Place the electrodes in glass vials for further characterization. After removing the remaining cell parts from the glove box, place the Swagelok parts, stainless steel rod, aluminum tubes, and aluminum meshes, in a beaker containing deionized water.Then, clean them with ultrasonication for 15 to 30 minutes. Finally, dry the cell parts and glass chamber in a thermostat set to 60 to 80 degrees Celsius. SCM images of the carbon powder before, and after the catalyst loading, demonstrate preservation of the porous surface structure.TEM images show the electro-catalyst nano particles, uniformly distribute on the carbon substrate, and well crystallized nano particles are shown in the high resolution TEM image. XANES spectra show that the electro-catalyst nano particles are partly oxidized, due to the preparation of cathodes in air. Typical voltage profiles for discharge and discharge-charge cycles are shown here.In the SCM image of the discharged cathode, the products have a toroidal shape, which is widely accepted as the primary morphology of lithium peroxide in a lithium-oxygen cell. Lithium peroxide and carbon peaks are observed in the XRD pattern of the discharged cathode, suggesting that side reactions are minimized in the cell. XPS spectra show that lithium peroxide and lithium hydroxide form on the cathode surface after discharging.Lithium peroxide is reduced, but lithium hydroxide remains after charging. A trace amount of lithium superoxide is detected by Raman spectroscopy. The hydroxide and carbonyl vibration signals in the FTIR spectra, indicate the presence of the ether electrolyte, as well as other hydroxide, carbonate, or carbonyl species, which are formed in side reactions.Once mastered, this type of cell can be assembled in five minutes, if it is performed appropriately. After its development, this technique paved the way for researchers in the metal-air battery field to explore battery performance in both electro-chemical testing and categorization of battery materials. While attempting this procedure, it is important to remember to operate in a glove box filled with argon to avoid side reactions and by-products.After watching this video, you should have a good understanding of how to study lithium-oxygen batteries systematically and efficiently. Don't forget that working with alkaline metals and organic solvents can be extremely hazardous, and precautions such as wearing gloves, working in a glove box, and working in a chemical fume hood, should be taken while performing this procedure.

protocol-electrochemical-test-characterization-aprotic-li-o2

Research

JoVE Journal

Engineering

Solid-state Graft Copolymer Electrolytes for Lithium Battery Applications

Battery safety has been a very important research area over the past decade. Commercially available lithium ion batteries employ low flash point (&lt;80 &deg;C), flammable, and volatile organic electrolytes. These organic based electrolyte systems are viable at ambient temperatures, but require a cooling system to ensure that temperatures do not exceed 80 &deg;C. These cooling systems tend to increase battery costs and can malfunction which can lead to battery malfunction and explosions, thus endangering human life. Increases in petroleum prices lead to a huge demand for safe, electric hybrid vehicles that are more economically viable to operate as oil prices continue to rise. Existing organic based electrolytes used in lithium ion batteries are not applicable to high temperature automotive applications. A safer alternative to organic electrolytes is solid polymer electrolytes. This work will highlight the synthesis for a graft copolymer electrolyte (GCE) poly(oxyethylene) methacrylate (POEM) to a block with a lower glass transition temperature (Tg) poly(oxyethylene) acrylate (POEA). The conduction mechanism has been discussed and it has been demonstrated the relationship between polymer segmental motion and ionic conductivity indeed has a Vogel-Tammann-Fulcher (VTF) dependence. Batteries containing commercially available LP30 organic (LiPF6 in ethylene carbonate (EC):dimethyl carbonate (DMC) at a 1:1 ratio) and GCE were cycled at ambient temperature. It was found that at ambient temperature, the batteries containing GCE showed a greater overpotential when compared to LP30 electrolyte. However at temperatures greater than 60 &deg;C, the GCE cell exhibited much lower overpotential due to fast polymer electrolyte conductivity and nearly the full theoretical specific capacity of 170 mAh/g was accessed.

Lithium ion batteries employ flammable and volatile organic electrolytes that are suitable for ambient temperature applications. A safer alternative to organic electrolytes are solid polymer batteries. Solid polymer batteries operate safely at high temperatures (&gt;120 &deg;C), thus making them applicable to high temperature applications such as deep oil drilling and hybrid electric vehicles. This paper will discuss (a) the polymer synthesis, (b) the polymer conduction mechanism, and (c) provide temperature cycling for both solid polymer and organic electrolytes.

Battery safety has been a very important research area over the past decade. Commercially available lithium ion batteries employ low flash point (&lt;80 ...

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM, other properties such as local electronic states, ion diffusion coefficient and surface potential can also be investigated17-22. In this work, electrochemical measurements, Raman spectroscopy, and SPM were used in conjunction with a novel test electrode platform that consists of a Ni mesh electrode embedded in an yttria-stabilized zirconia (YSZ) electrolyte. Cell performance testing and impedance spectroscopy under fuel containing H2S was characterized, and Raman mapping was used to further elucidate the nature of sulfur poisoning. In situ Raman monitoring was used to investigate coking behavior. Finally, atomic force microscopy (AFM) and electrostatic force microscopy (EFM) were used to further visualize carbon deposition on the nanoscale. From this research, we desire to produce a more complete picture of the SOFC anode.

We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen ...

Fabrication of VB2/Air Cells for Electrochemical Testing

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for synthesizing nanoscopic VB2 is presented as well as step-by-step procedure for applying a zirconium oxide coating to the VB2 particles for stabilization upon discharge. The process for disassembling existing zinc/air cells is shown, in addition construction of the new working electrode to replace the conventional zinc/air cell anode with a the nanoscopic VB2 anode. Finally, discharge of the completed VB2/air battery is reported. We show that using the zinc/air cell as a test bed is useful to provide a consistent configuration to study the performance of the high-energy high capacity nanoscopic VB2 anode.

Fabrication of VB2/Air Cells for Electrochemical Testing

A protocol is presented to study multi-electron metal/air battery systems by using previous technology developed for the zinc/air cell. Electrochemical testing is then performed on fabricated batteries to evaluate performance.

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for ...

Characterization of Electrode Materials for Lithium Ion and Sodium Ion Batteries Using Synchrotron Radiation Techniques

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. During insertion or removal of alkali metal ions, the redox states of transition metals in the compounds change and structural transformations such as phase transitions and/or lattice parameter increases or decreases occur. These behaviors in turn determine important characteristics of the batteries such as the potential profiles, rate capabilities, and cycle lives. The extremely bright and tunable x-rays produced by synchrotron radiation allow rapid acquisition of high-resolution data that provide information about these processes. Transformations in the bulk materials, such as phase transitions, can be directly observed using X-ray diffraction (XRD), while X-ray absorption spectroscopy (XAS) gives information about the local electronic and geometric structures (e.g.&#160;changes in redox states and bond lengths). In situ experiments carried out on operating cells are particularly useful because they allow direct correlation between the electrochemical and structural properties of the materials. These experiments are time-consuming and can be challenging to design due to the reactivity and air-sensitivity of the alkali metal anodes used in the half-cell configurations, and/or the possibility of signal interference from other cell components and hardware. For these reasons, it is appropriate to carry out ex situ experiments (e.g.&#160;on electrodes harvested from partially charged or cycled cells) in some cases. Here, we present detailed protocols for the preparation of both ex situ and in situ samples for experiments involving synchrotron radiation and demonstrate how these experiments are done.

We describe the use of synchrotron X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) techniques to probe details of intercalation/deintercalation processes in electrode materials for Li-ion and Na-ion batteries. Both in situ and ex situ experiments are used to understand structural behavior relevant to the operation of devices

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. ...

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. 
Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties.
The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale, results from a post-test microscopy analysis are presented.

Development of new ablative materials and their numerical modeling requires extensive experimental investigation. This protocol describes procedures for material response characterization in plasma flows with the core techniques being non-intrusive methods to track the material recession along with the chemistry in the reactive boundary layer by emission spectroscopy.

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution ...

Fabrication and Characterization of Superconducting Resonators

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors (MKIDs) for the detection of faint astrophysical signatures, as well as for quantum computing applications and materials characterization. In this paper, procedures are presented for the fabrication and characterization of thin-film superconducting microwave resonators. The fabrication methodology allows for the realization of superconducting transmission-line resonators with features on both sides of an atomically smooth single-crystal silicon dielectric. This work describes the procedure for the installation of resonator devices into a cryogenic microwave testbed and for cool-down below the superconducting transition temperature. The set-up of the cryogenic microwave testbed allows one to do careful measurements of the complex microwave transmission of these resonator devices, enabling the extraction of the properties of the superconducting lines and dielectric substrate (e.g., internal quality factors, loss and kinetic inductance fractions), which are important for device design and performance.

Superconducting microwave resonators are of interest for detection of light, quantum computing applications and materials characterization. This work presents a detailed procedure for fabrication and characterization of superconducting microwave resonator scattering parameters.

Superconducting microwave resonators are of interest for a wide range of applications, including for their use as microwave kinetic inductance detectors ...

Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. The results of studies in which the etching current and the molarity of the NaOH solution used in the etching process were varied are presented. The investigation of the geometry of the tips, by imaging them with a scanning electron microscope, and by operating them in field emission mode is also described. The field emission tips produced are intended to be used as an electron beam source for ion production via electron impact ionization of background gas or vapor in Penning trap mass spectrometry applications.

A method for electrochemically etching field emission tips is presented. Etching parameters are characterized and the operation of the tips in field emission mode is investigated.

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. ...

Fabrication of White Light-emitting Electrochemical Cells with Stable Emission from Exciplexes

The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active layer which consists of blue-fluorescent poly(9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFD) and &#960;-conjugated triphenylamine molecules. This white light emission originates from exciplexes formed between PFD and amines in electronically excited states. A device containing PFD, 4,4&#39;,4&#39;&#39;-tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA), Poly(ethylene oxide) and K2CF3SO3 showed white light emission with Commission internationale de l&#39;&#233;clairage (CIE) coordinates of (0.33, 0.43) and a Color Rendering Index (CRI) of Ra = 73 at an applied voltage of 3.5 V. Constant voltage measurements showed that the CIE coordinates of (0.27, 0.37), Ra of 67, and the emission color observed immediately after application of a voltage of 5 V were nearly unchanged and stable after 300 sec.

The authors present a method for fabricating stable white-light-emitting electrochemical cells utilizing emission from exciplexes formed between a blue-emitting fluorene polymer and aromatic amines.

The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active ...

Three-electrode Coin Cell Preparation and Electrodeposition Analytics for Lithium-ion Batteries

As lithium-ion batteries find use in high energy and power applications, such as in electric and hybrid-electric vehicles, monitoring the degradation and subsequent safety issues becomes increasingly important. In a Li-ion cell setup, the voltage measurement across the positive and negative terminals inherently includes the effect of the cathode and anode which are coupled and sum to the total cell performance. Accordingly, the ability to monitor the degradation aspects associated with a specific electrode is extremely difficult because the electrodes are fundamentally coupled. A three-electrode setup can overcome this problem. By introducing a third (reference) electrode, the influence of each electrode can be decoupled, and the electrochemical properties can be measured independently. The reference electrode (RE) must have a stable potential that can then be calibrated against a known reference, for example, lithium metal. The three-electrode cell can be used to run electrochemical tests such as cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). Three-electrode cell EIS measurements can elucidate the contribution of individual electrode impedance to the full cell. In addition, monitoring the anode potential allows the detection of electrodeposition due to lithium plating, which can cause safety concerns. This is especially important for the fast charging of Li-ion batteries in electric vehicles. In order to monitor and characterize the safety and degradation aspects of an electrochemical cell, a three-electrode setup can prove invaluable. This paper aims to provide a guide to constructing a three-electrode coin cell setup using the 2032-coin cell architecture, which is easy to produce, reliable, and cost-effective.

Three-electrode cells are useful in studying the electrochemistry of lithium-ion batteries. Such an electrochemical setup allows the phenomena associated with the cathode and anode to be decoupled and examined independently. Here, we present a guide for construction and use of a three-electrode coin cell with emphasis on lithium plating analytics.

As lithium-ion batteries find use in high energy and power applications, such as in electric and hybrid-electric vehicles, monitoring the degradation and ...

Optimization, Test and Diagnostics of Miniaturized Hall Thrusters

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without attendance and adjustment. Thermochemical thrusters which utilize thermodynamic properties of gases as a means of acceleration have physical limitations on their exhaust gas velocity, resulting in low efficiency. Moreover, these engines demonstrate extremely low efficiency at small thrusts and may be unsuitable for continuously operating systems which provide real-time adaptive control of the spacecraft orientation, velocity and position. In contrast, electric propulsion systems which use electromagnetic fields to accelerate ionized gases (i.e., plasmas) do not have any physical limitation in terms of exhaust velocity, allowing virtually any mass efficiency and specific impulse. Low-thrust Hall thrusters have a lifetime of several thousand hours. Their discharge voltage ranges between 100 and 300 V, operating at a nominal power of &lt;1 kW. They vary from 20 to 100 mm in size. Large Hall thrusters can provide fractions of millinewton of thrust. Over the past few decades, there has been an increasing interest in small mass, low power, and high efficiency propulsion systems to drive satellites of 50-200 kg. In this work, we will demonstrate how to build, test, and optimize a small (30 mm) Hall thruster capable of propelling a small satellite weighing about 50 kg. We will show the thruster operating in a large space environment simulator, and describe how thrust is measured and electric parameters, including plasma characteristics, are collected and processed to assess key thruster parameters. We will also demonstrate how the thruster is optimized to make it one of the most efficient small thrusters ever built. We will also address challenges and opportunities presented by new thruster materials.

Here, we present a protocol to test and optimize space propulsion systems based on miniaturized Hall-type thrusters.

Miniaturized spacecraft and satellites require smart, highly efficient and durable low-thrust thrusters, capable of extended, reliable operation without ...