This research was funded by the United States Office of Naval Research.

1. An emulsion-based method to create Zn-sponge electrodes
<ol>
	<li>Add 2.054 mL of deionized water to a 100 mL glass beaker.</li>
	<li>Add 4.565 mL of decane to the beaker.</li>
	<li>Stir in 0.1000 &#177; 0.0003 g of sodium dodecyl sulfate (SDS) until dissolved.</li>
	<li>Stir in 0.0050 &#177; 0.0003 g of water-soluble medium viscosity carboxymethyl cellulose (CMC) sodium salt by hand for 5 min or until the CMC is fully dissolved. 
	NOTE: Use plastic or plastic-coated stirring tools. Stirring with tools with a metallic surface can adversely affect resulting Zn sponges.</li>
	<li>Stir in 0.844 &#177; 0.002 g of water-insoluble preswollen carboxymethyl cellulose resin. 
	NOTE: This type of water-insoluble resin is expensive (USD$420 kg&#8211;1)6.</li>
	<li>Stir this mixture at 1,000 rpm for 5 min using an overhead paddle stirrer equipped with a plastic paddle.</li>
	<li>Pour 50 g of Zn powder (average particle size of 50 &#181;m, containing 307 ppm of bismuth and 307 ppm of indium for corrosion suppression) into the beaker while the overhead stirrer continues to spin at 1,000 rpm.</li>
	<li>Continue to stir the Zn paste for an additional 5 min at the same rate, 1,000 rpm.</li>
	<li>Stop the stirrer, remove the beaker, and outgas the mixture by placing the beaker and its contents under vacuum for 5 min in a desiccator at room temperature.</li>
	<li>Portion the Zn paste into polypropylene molds (~10 mm in diameter and ~5 mm in height) and let them dry in open air overnight. The shape of the mold dictates the form of the dried paste and resulting Zn sponges. 
	NOTE: Mold size and shape can vary. Past experiments5 successfully use cylindrical molds with diameters near 10&#160;mm. Fill the Zn paste up to a height of 5 mm or less. The shorter the height, the shorter the required drying time. See Table of Materials for commercially available molds.</li>
	<li>Carefully remove the dried Zn paste preforms from the molds and place them into a mesh casing that rests on a notched alumina holder5,6. 
	NOTE: Fabricate mesh casing, for instance, by bending a perforated-brass sheet into a cylinder with a diameter that is slightly larger than the desired diameter of the Zn-sponge electrode. Spray the perforated-metal sheet with boron-nitride lubricant after bending into a desired shape.</li>
	<li>Place the assembly into a tube furnace (67 mm in diameter) with ports to flow gas in and out of the tube. 
	NOTE: Use one port (the entrance port) to pipe gas into the furnace. Use the other (the exit port) to vent gas out of the tube furnace into a fume hood.</li>
	<li>Pipe N2 gas into the furnace for 30 min at a rate of 5.7&#160;cm&#8729;min&#8211;1 to purge the furnace of air. 
	NOTE: Step 1.13 can be achieved by connecting a tank of N2 gas with a digitally controlled flow meter to a tube connected to one of the entrance ports. Gas flow meters can be controlled manually or by a computer.</li>
	<li>Throttle the N2 gas to a constant rate of 2.8 cm&#8729;min&#8211;1 after the 30 min purge.</li>
	<li>Program the furnace to increase temperature linearly from 20 to 369 &#176;C over the course of 68 min, hold at 369 &#176;C for 5 h, rise linearly from 369 to 584 &#176;C over the course of 105 min, and then turn off.</li>
	<li>Start the furnace program while the N2 gas continues to flow.</li>
	<li>Manually stop the N2-gas flow after the 5 h temperature hold and pipe in breathing air at 2.8 cm&#8729;min&#8211;1. 
	NOTE: Step 1.17 can be achieved by connecting a tank of breathing air (not synthetic air) with a digitally controlled flow meter to a tube connected to an additional entrance port.</li>
	<li>Once the heating program stops, let the furnace cool to room temperature without active cooling, but keep the breathing air flowing.</li>
	<li>Remove the cooled Zn sponges and saw them and/or sand them to desired dimensions. 
	NOTE: A variety of sawing tools can be used such as hand-held rotary saws or vertical band saws. Abrasive or diamond blades are appropriate.</li>
</ol>
2. An aqueous-based method to create Zn-sponge electrodes
<ol>
	<li>Add 10.5 mL of deionized water to a 100-mL glass beaker.</li>
	<li>Stir in 0.120 &#177; 0.001 g of water-soluble high-viscosity cellulose gum, also known as carboxymethyl cellulose (CMC) sodium salt. 
	NOTE: Use plastic or plastic-coated stirring tools. Stirring with tools with a metallic surface can adversely affect resulting Zn sponges.</li>
	<li>Vortex and stir this mixture by hand for 5 min or until the CMC is dissolved.</li>
	<li>Stir in 2.400 &#177; 0.001 g of corn starch while vortexing for an additional 2 min.</li>
	<li>Stir in 120.00 &#177; 0.01 g of Zn powder (average particle size of 50 &#181;m, containing 307 ppm of bismuth and 307 ppm of indium for corrosion suppression) while vortexing for an additional 2 min.</li>
	<li>Press the resulting Zn paste into desired mold cavities. 
	NOTE: Mold size and shape can vary. Past experiments6 successfully use cylindrical molds with diameters near 10 mm. Fill the Zn paste up to a height of 50 mm or less. The aqueous Zn paste is dryer than the emulsion Zn paste, so the aqueous version can be used to make larger sponges that require less drying time. The shorter the height, the shorter the required drying time. The mold needs to be able to split in half as the aqueous Zn paste minimally contracts after drying, unlike the emulsion Zn paste. Unsalted butter can be used to lubricate the molds before pressing in the aqueous Zn paste to aid in demolding. Figure 1A shows the custom-machined molds packed with Zn paste following the aqueous-based protocol. Figure 1B shows the hand-made mesh casing, notched alumina holder, and resulting Zn sponge made using the aqueous-based method.</li>
	<li>Leave the Zn-paste-filled molds to dry overnight at 70 &#176;C in open air in a furnace.</li>
	<li>Follow the same handling and heat treatment steps (1.11&#8211;1.19) described for the emulsion-based method.</li>
</ol>

<ol>
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F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rechargeable+nickel-3D+zinc+batteries:+An+energy-dense,+safer+alternative+to+lithium-ion.">Rechargeable nickel-3D zinc batteries: An energy-dense, safer alternative to lithium-ion.</a> Science. 356 (6336), 415-418 (2017).</li><li>Ko, J. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Robust+3D+Zn+sponges+enable+high-power,+energy-dense+alkaline+batteries.">Robust 3D Zn sponges enable high-power, energy-dense alkaline batteries.</a> ACS Applied Energy Materials. 2 (1), 212-216 (2018).</li><li>Hopkins, B. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabricating+architected+zinc+electrodes+with+unprecedented+volumetric+capacity+in+rechargeable+alkaline+cells.">Fabricating architected zinc electrodes with unprecedented volumetric capacity in rechargeable alkaline cells.</a> Energy Storage Materials. 27, 370-376 (2020).</li><li>Hopkins, B. 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M., Mumm, D. R., Mohraz, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+Cyclability+of+ZnO+Electrodes+through+Microstructural+Design.">Improving Cyclability of ZnO Electrodes through Microstructural Design.</a> ACS Applied Energy Materials. 2 (11), 8107-8117 (2019).</li><li>Wang, C., Zhu, G., Liu, P., Chen, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monolithic+Nanoporous+Zn+Anode+for+Rechargeable+Alkaline+Batteries.">Monolithic Nanoporous Zn Anode for Rechargeable Alkaline Batteries.</a> ACS Nano. 14 (2), 2404-2411 (2020).</li><li>Drillet, J. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+Novel+Zinc/Air+Fuel+Cell+with+a+Zn+Foam+Anode,+a+PVA/KOH+Membrane+and+a+MnO2/SiOC-based+Air+Cathode.">Development of a Novel Zinc/Air Fuel Cell with a Zn Foam Anode, a PVA/KOH Membrane and a MnO2/SiOC-based Air Cathode.</a> ECS Transactions. 28, 13-24 (2010).</li><li>Bozzini, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphological+evolution+of+Zn-sponge+electrodes+monitored+by+in+situ+X-ray+computed+microtomography.">Morphological evolution of Zn-sponge electrodes monitored by in situ X-ray computed microtomography.</a> ACS Applied Energy Materials. , (2020).</li><li>Yang, Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Do+Zinc+Dendrites+Exist+in+Neutral+Zinc+Batteries:+A+Developed+Electrohealing+Strategy+to+In+Situ+Rescue+In-Service+Batteries.">Do Zinc Dendrites Exist in Neutral Zinc Batteries: A Developed Electrohealing Strategy to In Situ Rescue In-Service Batteries.</a> Advanced Materials. 31, 1903778 (2019).</li><li>Yang, Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen-Substituted+Graphdiyne+Ion+Tunnels+Directing+Concentration+Redistribution+for+Commercial-Grate+Dendrite-Free+Zinc+Anodes.">Hydrogen-Substituted Graphdiyne Ion Tunnels Directing Concentration Redistribution for Commercial-Grate Dendrite-Free Zinc Anodes.</a> Advanced Materials. 32, 2001755 (2020).</li><li>Narayanan, S. 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J.F.P., D.R.R., and J.W.L. hold patents related to zinc electrodes: US Patents no. 9802254, 10008711,&#160;10720635, and 10763500, EU Patent no 2926395, and China Patent no. 104813521.

Modifications and troubleshooting associated with these protocols include filling the freshly mixed Zn paste into a mold cavity. Care should be taken to avoid air pockets. Unwanted voids can be decreased by tapping the mold after filling or while filling. Because the aqueous Zn paste is dry, pressure can be applied directly to the Zn paste to push out air pockets while filling up the mold cavity.
A limitation of the methods is that Zn-sponge pore structure is disordered, but the Zn and porogen...

The purpose of the reported fabrication methods is to create zinc (Zn) sponge electrodes that suppress dendrite formation and shape change. Historically, these problems have limited the cycle life of Zn batteries. Zinc-sponge electrodes have resolved these issues, enabling Zn batteries with longer cycle lives1,2,3,4,5,6. The sponge structure suppresses dendrite formation and shape change because (1) the fused Zn framework electrically wires the entire volume of the sponge; (2) the pores hold zincate near the Zn-sponge surface; and (3) the sponge has a high surface area that decreases local current density below values identified to sprout dendrites in alkaline electrolytes7. However, if sponge surface area is too high, substantial corrosion occurs5. If the sponge pores are too large, the sponge will have a low volumetric capacity5. Also, if the sponge pores are too small, the Zn electrode will have insufficient electrolyte to access Zn during discharge, resulting in low power and capacity5,6.
The rationale behind the reported fabrication methods is to create Zn sponges with appropriate sponge porosities and pore diameters. Experimentally, we find that Zn sponges with porosities from 50 to 70% and pore diameters near 10&#160;&#181;m cycle well in full-cell batteries and display low corrosion rates5. We note that existing methods to manufacture commercial metal foams fail to achieve similar morphologies on these length scales8, so the reported fabrication methods are needed.
The advantages of the methods reported here over alternatives are characterized by fine control of sponge features and by the ability to fabricate large, dense Zn sponges with technologically relevant areal-capacity values5,6,9,10. Alternative methods to create Zn foams may be unable to create comparable 10 &#181;m pores with sponge porosities near 50%. Such alternatives may, however, require less energy to fabricate because they avoid high-temperature processing steps. Alternative processes include the following strategies: cold sintering Zn particles11, depositing Zn on three-dimensional host structures12,13,14,15,16,17, cutting Zn foil into two-dimensional foams18, and creating Zn foams via spinodal decomposition19 or percolation dissolution20.
The context of the reported methods in the wider body of the published literature is primarily established by work from Drillet et al.21. They adapted methods of fabricating porous ceramics to create one of the earliest reported three-dimensional, albeit fragile, Zn foams for batteries. These authors, however, failed to demonstrate rechargeability, likely because of the poor connectivity between the Zn particles. Prior to rechargeable Zn-sponge electrodes, the best alternative to a Zn foil electrode was a Zn-powder electrode, wherein Zn powder is mixed with a gel electrolyte. Zinc-powder electrodes are commercially used in primary alkaline batteries (Zn&#8211;MnO2) but have poor rechargeability because Zn particles become passivated by Zn oxide (ZnO), which can increase local current density that spurs dendrite growth3,22. We note that there are other dendrite-suppression strategies that do not involve foam or sponge architectures23,24.
The reported Zn-sponge fabrication methods require a tube furnace, sources of air and nitrogen gas (N2), and a fume hood. All steps can be performed at a lab desk without environmental control, but exhaust from the tube furnace during heat treatment should be piped to a fume hood. Resulting electrodes are appropriate for those interested in creating rechargeable Zn electrodes capable of high areal capacity (&#62; 10 mAh cmgeo&#8211;2)6.
The first reported fabrication method is an emulsion-based route to create Zn-sponge electrodes. The second, is an aqueous-based route. An advantage of the emulsion route is its ability to create Zn paste that, when dried, is easy to demold from a mold cavity. A disadvantage is its reliance on expensive materials. For the aqueous route, sponge preforms can be challenging to demold, but this process uses inexpensive and abundant materials.
Both methods involve mixing Zn particles with a porogen and viscosity-enhancing agent. The resulting mixture is heated under N2 and then breathing air (not synthetic air). During heating under N2, the Zn particles anneal and the porogen decomposes; under breathing air, the annealed Zn particles fuse and the porogen burns out. These processes yield metal foams or sponges. The mechanical and electrochemical properties of the Zn sponges can be tuned by varying Zn-to-porogen mass ratio, heating time under N2 and air, and size and shape of the Zn and porogen particles.

<table>
	<tbody>
		<tr>
			<td>Corn starch</td>
			<td>Argo</td>
			<td>Not applicable</td>
			<td>This acts as a porogen and viscosity-enhancing agent.</td>
		</tr>
		<tr>
			<td>Decane</td>
			<td>MilliporeSigma</td>
			<td>D901</td>
			<td></td>
		</tr>
		<tr>
			<td>Medium viscosity water-soluble carboxymethyl cellulose (CMC) sodium salt</td>
			<td>MilliporeSigma</td>
			<td>C4888-500G</td>
			<td>This CMC acts primarily as a viscosity-enhancing agent.</td>
		</tr>
		<tr>
			<td>Overhead stirrer</td>
			<td>Caframo Lab Solutions</td>
			<td>BDC3030</td>
			<td></td>
		</tr>
		<tr>
			<td>Small cylindrical models for Zn sponges</td>
			<td>VWR</td>
			<td>66014-358</td>
			<td>The caps of the vials can be used as molds.</td>
		</tr>
		<tr>
			<td>Sodium dodecyl sulfate</td>
			<td>MilliporeSigma</td>
			<td>436143</td>
			<td></td>
		</tr>
		<tr>
			<td>Water-insoluble IonSep CMC 52 preswollen carboxymethyl cellulose resin</td>
			<td>BIOpHORETICS</td>
			<td>B45019.01</td>
			<td>This CMC acts as a porogen and viscosity-enhancing agent.</td>
		</tr>
		<tr>
			<td>Zn powder</td>
			<td>EverZinc</td>
			<td>Custom order</td>
			<td></td>
		</tr>
	</tbody>
</table>

zinc-sponge battery electrodes that suppress dendrites

We report two methods to create zinc-sponge electrodes that suppress dendrite formation and shape change for rechargeable zinc batteries. Both methods are characterized by creating a paste made of zinc particles, organic porogen, and viscosity-enhancing agent that is heated under an inert gas and then air. During heating under the inert gas, the zinc particles anneal together, and the porogen decomposes; under air, the zinc fuses and residual organic burns out, yielding an open-cell metal foam or sponge. We tune the mechanical and electrochemical properties of the zinc sponges by varying zinc-to-porogen mass ratio, heating time under inert gas and air, and size and shape of the zinc and porogen particles. An advantage of the reported methods is their ability to finely tune zinc-sponge architecture. The selected size and shape of the zinc and porogen particles influence the morphology of the pore structure. A limitation is that resulting sponges have disordered pore structures that result in low mechanical strength at low volume fractions of zinc (&#60;30%). Applications for these zinc-sponge electrodes include batteries for grid-storage, personal electronics, electric vehicles, and electric aviation. Users can expect zinc-sponge electrodes to cycle up to 40% depth of discharge at technologically relevant rates and areal capacities without the formation of separator-piercing dendrites.

Resulting, fully heat-treated, emulsion-based Zn sponges have densities of 2.8 g&#8729;cm&#8211;3 while aqueous-based sponges approach 3.3 g&#8729;cm&#8211;3. During heating under air, a layer of ZnO forms on the Zn surfaces, which should have a thickness of 0.5&#8211;1.0 &#181;m (observed using scanning electron microscopy)5. The solid in the resulting sponges should be 72% Zn (emulsion version) or 78% Zn (aqueous version) with the remainder being ZnO (measured by X-ray diff...

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Zinc-Sponge Battery Electrodes that Suppress Dendrites

The goal of the reported protocols is to create rechargeable zinc-sponge electrodes that suppress dendrites and shape change in zinc batteries, such as nickel&#8211;zinc or zinc&#8211;air.

We report two methods to create zinc-sponge electrodes that suppress dendrite formation and shape change for rechargeable zinc batteries. Both methods are ...

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4.2K Views.  U.S. Naval Research Laboratory, Washington, DC, 20375, United States. The goal of the reported protocols is to create rechargeable zinc-sponge electrodes that suppress dendrites and shape change in zinc batteries, such as nickel–zinc or zinc–air.

Video: Zinc-Sponge Battery Electrodes that Suppress Dendrites

Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes

Controllable electrode surface modification is important in a number of fields, especially those with solar fuels applications. Electropolymerization is one surface modification technique that electrodeposits a polymeric film at the surface of an electrode by utilizing an applied potential to initiate the polymerization of substrates in the Helmholtz layer. This useful technique was first established by a Murray-Meyer collaboration at the University of North Carolina at Chapel Hill in the early 1980s and utilized to study numerous physical phenomena of films containing inorganic complexes as the monomeric substrate. Here, we highlight a procedure for coating electrodes with an inorganic complex by performing reductive electropolymerization of the vinyl-containing poly-pyridyl complex onto glassy carbon and fluorine doped tin oxide coated electrodes. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization but are far less sensitive to oxygen and water.

A procedure for performing reductive electropolymerization of vinyl-containing compounds onto glassy carbon and fluorine doped tin-oxide coated electrodes is presented. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization.

Controllable electrode surface modification is important in a number of fields, especially those with solar fuels applications. Electropolymerization is ...

A Colorimetric Assay that Specifically Measures Granzyme B Proteolytic Activity: Hydrolysis of Boc-Ala-Ala-Asp-S-Bzl

The serine protease Granzyme B (GzmB) mediates target cell apoptosis when released by cytotoxic T lymphocytes (CTL) or natural killer (NK) cells. GzmB is the most studied granzyme in humans and mice and therefore, researchers need specific and reliable tools to study its function and role in pathophysiology. This especially necessitates assays that do not recognize proteases such as caspases or other granzymes that are structurally or functionally related. Here, we apply GzmB&#8217;s preference for cleavage after aspartic acid residues in a colorimetric assay using the peptide thioester Boc-Ala-Ala-Asp-S-Bzl. GzmB is the only mammalian serine protease capable of cleaving this substrate. The substrate is cleaved with similar efficiency by human, mouse and rat GzmB, a property not shared by other commercially available peptide substrates, even some that are advertised as being suitable for this purpose. This protocol is demonstrated using unfractionated lysates from activated NK cells or CTL and is also suitable for recombinant proteases generated in a variety of prokaryotic and eukaryotic systems, provided the correct controls are used. This assay is a highly specific method to ascertain the potential pro-apoptotic activity of cytotoxic molecules in mammalian lymphocytes, and of their recombinant counterparts expressed by a variety of methodologies.

We describe a simple, quantitative colorimetric assay that specifically measures the proteolytic activity of human, mouse or rat Granzyme B (GzmB). This protocol can be easily adapted for determining protease activity of other granule serine proteases by the hydrolysis of other synthetic peptide substrates with an appropriate recognition sequence.

The serine protease Granzyme B (GzmB) mediates target cell apoptosis when released by cytotoxic T lymphocytes (CTL) or natural killer (NK) cells. GzmB is ...

Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from their extraction to the core during terrestrial accretion. Experiments to investigate the partitioning of these elements between metal and silicate melts suggest that the PUM composition is best matched if metal-silicate equilibrium occurred at high pressures and temperatures, in a deep magma ocean environment. The behavior of the most highly siderophile elements (HSEs) during this process however, has remained enigmatic. Silicate run-products from HSE solubility experiments are commonly contaminated by dispersed metal inclusions that hinder the measurement of element concentrations in the melt. The resulting uncertainty over the true solubility and metal-silicate partitioning of these elements has made it difficult to predict their expected depletion in PUM. Recently, several studies have employed changes to the experimental design used for high pressure and temperature solubility experiments in order to suppress the formation of metal inclusions. The addition of Au (Re, Os, Ir, Ru experiments) or elemental Si (Pt experiments) to the sample acts to alter either the geometry or rate of sample reduction respectively, in order to avoid transient metal oversaturation of the silicate melt. This contribution outlines procedures for using the piston-cylinder and multi-anvil apparatus to conduct solubility and metal-silicate partitioning experiments respectively. A protocol is also described for the synthesis of uncontaminated run-products from HSE solubility experiments in which the oxygen fugacity is similar to that during terrestrial core-formation. Time-resolved LA-ICP-MS spectra are presented as evidence for the absence of metal-inclusions in run-products from earlier studies, and also confirm that the technique may be extended to investigate Ru. Examples are also given of how these data may be applied.

We present a procedure to determine the metal-silicate partitioning of siderophile elements, emphasizing techniques that suppress the formation of metal inclusions in experiments for the noble metals. The results of these experiments are used to demonstrate the effect of core-formation on the highly siderophile element composition of the mantle.

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from ...

A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery

Redox flow batteries have been considered as one of the most promising stationary energy storage solutions for improving the reliability of the power grid and deployment of renewable energy technologies. Among the many flow battery chemistries, non-aqueous flow batteries have the potential to achieve high energy density because of the broad voltage windows of non-aqueous electrolytes. However, significant technical hurdles exist currently limiting non-aqueous flow batteries to demonstrate their full potential, such as low redox concentrations, low operating currents, under-explored battery status monitoring, etc. In an attempt to address these limitations, we recently reported a non-aqueous flow battery based on a highly soluble, redox-active organic nitronyl nitroxide radical compound, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). This redox material exhibits an ambipolar electrochemical property, and therefore can serve as both anolyte and catholyte redox materials to form a symmetric flow battery chemistry. Moreover, we demonstrated that Fourier transform infrared (FTIR) spectroscopy could measure the PTIO concentrations during the PTIO flow battery cycling and offer reasonably accurate detection of the battery state of charge (SOC), as cross-validated by electron spin resonance (ESR) measurements. Herein we present a video protocol for the electrochemical evaluation and SOC diagnosis of the PTIO symmetric flow battery. With a detailed description, we experimentally demonstrated the route to achieve such purposes. This protocol aims to spark more interests and insights on the safety and reliability in the field of non-aqueous redox flow batteries.

We present the protocols for electrochemically evaluating a symmetric non-aqueous organic redox flow battery and for diagnosing its state of charge using FTIR.

Redox flow batteries have been considered as one of the most promising stationary energy storage solutions for improving the reliability of the power grid ...

Simple Methods for the Preparation of Non-noble Metal Bulk-electrodes for Electrocatalytic Applications

The rock material pentlandite with the composition Fe4.5Ni4.5S8 was synthesized via high temperature synthesis from the elements. The structure and composition of the material was characterized via powder X-ray diffraction (PXRD), M&#246;ssbauer spectroscopy (MB), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and energy dispersive X-ray spectroscopy (EDX). Two preparation methods of pentlandite bulk electrodes are presented. In the first approach a piece of synthetic pentlandite rock is directly contacted via a wire ferrule. The second approach utilizes pentlandite pellets, pressed from finely ground powder, which is immobilized in a Teflon casing. Both electrodes, whilst being prepared by an additive-free method, reveal high durability during electrocatalytic conversions in comparison to common drop-coating methods. We herein showcase the striking performance of such electrodes to accomplish the hydrogen evolution reaction (HER) and present a standardized method to evaluate the electrocatalytic performance by electrochemical and gas chromatographic methods. Furthermore, we report stability tests via potentiostatic methods at an overpotential of 0.6 V to explore the material limitations of the electrodes during electrolysis under industrial relevant conditions.

A facile preparation method of electrodes using the bulk material Fe4.5Ni4.5S8 is presented. This method provides an alternative technique to conventional electrode fabrication and describes prerequisites for unconventional electrode materials including a straightforward electrocatalytic testing method.

The rock material pentlandite with the composition Fe4.5Ni4.5S8 was synthesized via high temperature synthesis from the elements. The structure and ...

Accelerating Rate Calorimetry and Complementary Techniques to Characterize Battery Safety Hazards

The hazards associated with lithium-based battery chemistries are well-documented due to their catastrophic nature. Risk is typically qualitatively assessed through an engineering risk matrix. Within the matrix, potentially hazardous events are categorized and ranked in terms of severity and probability to provide situational awareness to decision makers and stakeholders. The stochastic nature of battery failures, particularly the lithium-ion chemistry, makes the probability axis of a matrix difficult to properly assess. Fortunately, characterization tools exist, such as accelerated rate calorimetry (ARC), that characterize degrees of battery failure severity. ARC has been used extensively to characterize reactive chemicals but can provide a new application to induce battery failures under safe, controlled experimental conditions and quantify critical safety parameters. Due to the robust nature of the extended volume calorimeter, cells may be safely taken to failure due to a variety of abuses: thermal (simple heating of cell), electrochemical (overcharge), electrical (external short circuit), or physical (crush or nail penetration). This article describes the procedures to prepare and instrument a commercial lithium-ion battery cell for failure in an ARC to collect valuable safety data: onset of thermal runaway, endotherm associated with polymer separator melting, pressure release during thermal runaway, gaseous collection for analytical characterization, maximum temperature of complete reaction, and visual observation of decomposition processes using a high temperature borescope (venting and cell can breach). A thermal &#8220;heat-wait-seek&#8221; method is used to induce cell failure, in which the battery is heated incrementally to a set point, then the instrument identifies heat generation from the battery. As heat generates a temperature rise in the battery, the calorimeter temperature follows this temperature rise, maintaining an adiabatic condition. Therefore, the cell does not exchange heat with the external environment, so all heat generation from the battery under failure is captured.

A method to characterize the potential failure hazards of lithium batteries is achieved with accelerating rate calorimetry. Heat and pressure release, visual observation of the failure event, and the capture of evolved gases are collected in this experiment to identify the worst credible threats of batteries taken to failure.

The hazards associated with lithium-based battery chemistries are well-documented due to their catastrophic nature. Risk is typically qualitatively ...

Fabrication of Thin Film Silver/Silver Chloride Electrodes with Finely Controlled Single Layer Silver Chloride

This paper aims to present a protocol to form smooth and well-controlled films of silver/silver chloride (Ag/AgCl) with designated coverage on top of thin film silver electrodes. Thin film silver electrodes sized 80 &#181;m x 80 &#181;m and 160 &#181;m x 160 &#181;m were sputtered on quartz wafers with a chromium/gold (Cr/Au) layer for adhesion. After passivation, polishing and cathodic cleaning processes, the electrodes underwent galvanostatic oxidation with consideration of Faraday&#39;s Law of Electrolysis to form smooth layers of AgCl with a designated degree of coverage on top of the silver electrode. This protocol is validated by inspection of scanning electron microscope (SEM) images of the surface of the fabricated Ag/AgCl thin film electrodes, which highlights the functionality and performance of the protocol. Sub-optimally fabricated electrodes are fabricated as well for comparison. This protocol can be widely used to fabricate Ag/AgCl electrodes with specific impedance requirements (e.g., probing electrodes for impedance sensing applications like impedance flow cytometry and interdigitated electrode arrays).

This paper aims to present a method to form smooth and well-controlled films of silver chloride (AgCl) with designated coverage on top of thin film silver electrodes.

This paper aims to present a protocol to form smooth and well-controlled films of silver/silver chloride (Ag/AgCl) with designated coverage on top of thin ...

Screening of Coatings for an All-Solid-State Battery Using In Situ Transmission Electron Microscopy

With the ever-increasing use of Li-ion batteries, especially due to their adoption in electric vehicles, their safety is in prime focus. Thus, the all-solid-state batteries (ASSBs) that use solid electrolytes instead of liquid electrolytes, which reduce the risk of flammability, have been the center stage of battery research for the last few years. However, in the ASSB, the ion transportation through the solid-solid electrolyte-electrode interface poses a challenge due to contact and chemical/electrochemical stability issues. Applying a suitable coating around the electrode and/or electrolyte particles offers a convenient solution, leading to better performance. For this, researchers are screening potential electronic/ionic conductive and nonconductive coatings to find the best coatings with suitable thickness for long-term chemical, electrochemical, and mechanical stability. Operando transmission electron microscopy (TEM) couples high spatial resolution with high temporal resolution to allow visualization of dynamic processes, and thus is an ideal tool to evaluate electrode/electrolyte coatings via studying (de)lithiation at a single particle level in real-time. However, the accumulated electron dose during a typical high-resolution in situ work may affect the electrochemical pathways, evaluation of which can be time-consuming. The current protocol presents an alternative procedure in which the potential coatings are applied on Si nanoparticles and are subjected to (de)lithiation during operando TEM experiments. The high volume changes of Si nanoparticles during (de)lithiation allow monitoring of the coating behavior at a relatively low magnification. Thus, the whole process is very electron-dose efficient and offers quick screening of potential coatings.

Screening of Coatings for an All-Solid-State Battery Using In Situ Transmission Electron Microscopy

Utilizing the volume change of Si nanoparticles during (de)lithiation, the present protocol describes a screening method of potential coatings for all-solid-state batteries using in situ transmission electron microscopy.