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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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 particle sizes can be used to alter pore morphology. A more ordered and potentially stronger and lighter Zn sponge may be fabricated using additive manufacturing. The mechanical and electrochemical properties of resulting Zn sponges, however, can be tuned by varying Zn-to-porogen mass ratio and the size and shape of the Zn and porogen particles5,6. Another potential limitation is that the dried Zn-paste can be fragile, so transferring it into a mesh casing may be challenging and limit Zn-sponge size.
The significance of these methods with respect to existing methods is that resulting Zn sponges achieve long cycle life with high volumetric and areal capacities5,6. Resulting Zn sponges are also mechanically robust5,6.
Future applications of the processes could, in principle, be adapted to create other metal foams for batteries or other applications. For example, iron, magnesium, or aluminum foams may be useful as anodes for metal&#8211;air batteries25,26,27. Zn-sponge electrodes, in particular, can be used to create batteries for a range of applications that include wearables, grid storage, personal electronics, electric vehicles, and electric aviation28.
A critical step, which may also require modification or troubleshooting, is the heating process. Furnace temperatures can vary. The heating time under N2, near but below the melting point of Zn, anneals the Zn particles together. The heating time under air burns out the residual porogen, fuses the Zn, and forms a ZnO layer. If the Zn particles appear to be fusing improperly, increase the heating time under N2. If the ZnO layer is too thick, decrease the heating time under air by 10 min or more until the desired thickness of thermal oxide is achieved.
We note that a thick layer of ZnO enhances the mechanical properties of the Zn sponge but also decreases the immediately useable capacity of the Zn electrode. The Zn electrode can be charged by electrochemically converting ZnO to metallic Zn. However, stable cycling at 40% depth of discharge can be achieved without any precharge5. If the ZnO layer is too thin, the Zn sponge can crumble during handling5.

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 diffraction)6. Both sponges should have porosities near 50%, pore-diameter distributions centered on 10 &#181;m, and specific surface areas of 4.0 m2&#8729;g&#8211;1 (measured via mercury-intrusion porosimetry)6. The tensile strength of both sponges should be 1.1&#8211;1.2 MPa (measured with diametral compression)5,6. We note that the sponges should be rigid and brittle. Cross-sections of the Zn sponges should look similar to those shown in Figure 2A,B. If all the properties of the fabricated sponges fall within the provided ranges, the result is positive; if not, the result is negative.
With the stated properties, Zn sponges cycle well in properly constructed batteries. Their performance also depends on the counter electrode, electrolyte, separator, and cell construction; construction of reliable full cells is beyond the scope of this paper. To test the electrochemical validity of Zn sponges, we recommend harvesting commercial counter electrodes from nickel&#8211;metal hydride batteries5,6. Shape a Zn-sponge to have a 10 mm diameter and 0.5-mm thickness. Cycle this sponge at 20 mA&#8729;cmgeo&#8211;2 (geometric area) for discharge and 10 mA&#8729;cmgeo&#8211;2 for charge in a nickel&#8211;zinc cell as described in the literature5. Assuming appropriate construction, the Zn-sponge electrode should show cycling stability at a gravimetric capacity of 328&#160;mA&#8729;h&#8729;gsponge-1&#160;(per gram&#160;of&#160;ZnO@Zn-sponge&#160;electrode) as shown in Figure 2C, which maps to 43% depth of discharge (the quotient of gravimetric discharge capacity with respect to every atom of Zn in the electrode divided by the theoretical gravimetric capacity of Zn). After extensive cycling, no dendrites are observed by scanning electron microscopy (Figure 3). X-ray diffraction can be used to track the state of charge of the Zn-sponge electrode by monitoring Zn and ZnO reflections1. We note the surface of the Zn sponge undergoes restructuring during cycling. The deeper the level of discharge and the greater the cycle life, the greater the amount of restructuring5. These factors contribute to the difference in surface morphology shown in Figure 3A,B. If this rechargeable capacity is achieved, the result is positive; if not, the result is negative and could be caused by either the Zn sponge, poor cell construction, or failure of other cell components.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/61770/61770fig01.jpg" /> 
Figure 1: Zinc sponges before and after heat treatment using the aqueous-based method.&#160;(A) Photo of custom-machined molds made from Delrin or polyoxymethylene (POM) that is packed with Zn paste before heating occurs. (B) Photo of hand-made mesh casing, notched alumina holder, and resulting Zn sponge after heat treatment. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61770/61770fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/61770/61770fig02.jpg" /> 
Figure 2: Zinc-sponge morphology and electrochemical performance.&#160;Scanning electron micrographs of cross-sectioned (A) emulsion-based Zn sponge and (B) aqueous-based Zn sponge. (C) Voltage versus time of an emulsion-based sponge cycled in a nickel&#8211;zinc cell discharged at 20 mA&#8729;cmgeo&#8211;2 and charged at 10 mA&#8729;cmgeo&#8211;2 with a gravimetric capacity of 328 mA&#8729;h&#8729;gsponge&#8211;1. Data adapted from Hopkins et al.5,6. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61770/61770fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/61770/61770fig03.jpg" /> 
Figure 3: Zinc-sponge electrodes suppress dendrite formation.&#160;Emulsion-based Zn sponge (A) before and (B) after electrochemical cycling. Data adapted from Hopkins et al.5. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/61770/61770fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Zinc-Sponge Battery Electrodes that Suppress Dendrites at JoVE.com

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 ...

zinc-sponge-battery-electrodes-that-suppress-dendrites

Nanyang Technological University

Research

JoVE Journal

Chemistry

4.3K Views.  U.S. Naval Research Laboratory, Washington, DC, 20375, United States. Het doel van de gerapporteerde protocollen is om oplaadbare zinksponselektroden te maken die dendrieten en vormverandering in zinkbatterijen, zoals nikkel-zink of zink-lucht, onderdrukken.

Video: Zinc-Sponge Battery Electrodes that Suppress Dendrites

Construction and Testing of Coin Cells of Lithium Ion Batteries

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime. Lithium ion batteries have also been considered to be used in electric and hybrid vehicles1 or even electrical grid stabilization systems2. All these applications simulate a dramatic increase in the research and development of battery materials3-7, including new materials3,8, doping9, nanostructuring10-13, coatings or surface modifications14-17 and novel binders18. Consequently, an increasing number of physicists, chemists and materials scientists have recently ventured into this area. Coin cells are widely used in research laboratories to test new battery materials; even for the research and development that target large-scale and high-power applications, small coin cells are often used to test the capacities and rate capabilities of new materials in the initial stage. 
 In 2010, we started a National Science Foundation (NSF) sponsored research project to investigate the surface adsorption and disordering in battery materials (grant no. DMR-1006515). In the initial stage of this project, we have struggled to learn the techniques of assembling and testing coin cells, which cannot be achieved without numerous help of other researchers in other universities (through frequent calls, email exchanges and two site visits). Thus, we feel that it is beneficial to document, by both text and video, a protocol of assembling and testing a coin cell, which will help other new researchers in this field. This effort represents the "Broader Impact" activities of our NSF project, and it will also help to educate and inspire students.
In this video article, we document a protocol to assemble a CR2032 coin cell with a LiCoO2 working electrode, a Li counter electrode, and (the mostly commonly used) polyvinylidene fluoride (PVDF) binder. To ensure new learners to readily repeat the protocol, we keep the protocol as specific and explicit as we can. However, it is important to note that in specific research and development work, many parameters adopted here can be varied. First, one can make coin cells of different sizes and test the working electrode against a counter electrode other than Li. Second, the amounts of C black and binder added into the working electrodes are often varied to suit the particular purpose of research; for example, large amounts of C black or even inert powder were added to the working electrode to test the "intrinsic" performance of cathode materials14. Third, better binders (other than PVDF) have also developed and used18. Finally, other types of electrolytes (instead of LiPF6) can also be used; in fact, certain high-voltage electrode materials will require the uses of special electrolytes7.

A protocol to construct and test coin cells of lithium ion batteries is described. The specific procedures of making a working electrode, preparing a counter electrode, assembling a cell inside a glovebox and testing the cell are presented.

Rechargeable lithium ion batteries have wide applications in electronics, where customers always demand more capacity and longer lifetime.  Lithium ion ...

Engineering

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. ...

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric vehicles.1,2 However, many challenges, such as energy density and battery lifetimes, need to be overcome before this particular battery technology can be widely implemented in such applications.3 This research is challenging, and we outline a method to address these challenges using in situ NPD to probe the crystal structure of electrodes undergoing electrochemical cycling (charge/discharge) in a battery. NPD data help determine the underlying structural mechanism responsible for a range of electrode properties, and this information can direct the development of better electrodes and batteries.
We briefly review six types of battery designs custom-made for NPD experiments and detail the method to construct the &#8216;roll-over&#8217; cell that we have successfully used on the high-intensity NPD instrument, WOMBAT, at the Australian Nuclear Science and Technology Organisation (ANSTO). The design considerations and materials used for cell construction are discussed in conjunction with aspects of the actual in situ NPD experiment and initial directions are presented on how to analyze such complex in situ data.

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

We describe the design and construction of an electrochemical cell for the examination of electrode materials using in situ neutron powder diffraction (NPD). We briefly comment on alternate in situ NPD cell designs and discuss methods for the analysis of the corresponding in situ NPD data produced using this cell.

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric ...

Failure Analysis of Batteries Using Synchrotron-based Hard X-ray Microtomography

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent of lithium-ion batteries, researchers have known that the lithium metal anode has the highest theoretical energy density of any anode material. However, rechargeable batteries containing a lithium metal anode are not widely used in consumer products because the growth of lithium dendrites from the anode upon charging of the battery causes premature cell failure by short circuit. Lithium dendrites can also form in commercial lithium-ion batteries with graphite anodes if they are improperly charged. We demonstrate that lithium dendrite growth can be studied using synchrotron-based hard X-ray microtomography. This non-destructive imaging technique allows researchers to study the growth of lithium dendrites, in addition to other morphological changes inside batteries, and subsequently develop methods to extend battery life.

Synchrotron-based hard X-ray microtomography is used to image the electrochemical growth of dendrites from a lithium metal electrode through a solid polymer electrolyte membrane.

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent ...

Non-aqueous Electrode Processing and Construction of Lithium-ion Coin Cells

Research into new and improved materials to be utilized in lithium-ion batteries (LIB) necessitates an experimental counterpart to any computational analysis. Testing of lithium-ion batteries in an academic setting has taken on several forms, but at the most basic level lies the coin cell construction. In traditional LIB electrode preparation, a multi-phase slurry composed of active material, binder, and conductive additive is cast out onto a substrate. An electrode disc can then be punched from the dried sheet and used in the construction of a coin cell for electrochemical evaluation. Utilization of the potential of the active material in a battery is critically dependent on the microstructure of the electrode, as an appropriate distribution of the primary components are crucial to ensuring optimal electrical conductivity, porosity, and tortuosity, such that electrochemical and transport interaction is optimized. Processing steps ranging from the combination of dry powder, wet mixing, and drying can all critically affect multi-phase interactions that influence the microstructure formation. Electrochemical probing necessitates the construction of electrodes and coin cells with the utmost care and precision. This paper aims at providing a step-by-step guide of non-aqueous electrode processing and coin cell construction for lithium-ion batteries within an academic setting and with emphasis on deciphering the influence of drying and calendaring.

Non-aqueous electrode processing is central to the construction of coin cells and the evaluation of new electrode chemistries for lithium-ion batteries. A step-by-step guide to the basic practices needed as an electrochemical engineer working with batteries in an academic experimental setting is furnished.

Research into new and improved materials to be utilized in lithium-ion batteries (LIB) necessitates an experimental counterpart to any computational ...

In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate multiple processes responsible for long-term performance decay. Given the complexity of physical processes occurring inside the cell, it is often challenging to achieve a full understanding of the root causes of this performance degradation. This difficulty arises in part from the fact that any electrochemical measurement of a battery will return the combined contributions of all components in the cell. Incorporation of a reference electrode can solve part of the problem, as it allows the electrochemical reactions of the cathode and the anode to be individually probed. A variation in the voltage range experienced by the cathode, for example, can indicate alterations in the pool of cyclable lithium ions in the full-cell. The structural evolution of the many interphases existing in the battery can also be monitored, by measuring the contributions of each electrode to the overall cell impedance. Such wealth of information amplifies the reach of diagnostic analysis in Li-ion batteries and provides valuable input to the optimization of individual cell components. In this work, we introduce the design of a test cell able to accommodate multiple reference electrodes, and present reference electrodes that are appropriate for each specific type of measurement, detailing the assembly process in order to maximize the accuracy of the experimental results.

The incorporation of reference electrodes in a Li-ion battery provides valuable information to elucidate degradation mechanisms at high voltages. In this article, we present a cell design that accommodates multiple reference electrodes, along with the assembly steps to assure maximum accuracy of the data obtained in electrochemical measurements.

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate ...

Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid based on volatile solar and wind sources. The pressing demand of developing high-performance electrochemical energy storage solutions, i.e., batteries, relies on both fundamental understanding and practical developments from both the academy and industry. The formidable challenge of developing successful battery technology stems from the different requirements for different energy-storage applications. Energy density, power, stability, safety, and cost parameters all have to be balanced in batteries to meet the requirements of different applications. Therefore, multiple battery technologies based on different materials and mechanisms need to be developed and optimized. Incisive tools that could directly probe the chemical reactions in various battery materials are becoming critical to advance the field beyond its conventional trial-and-error approach. Here, we present detailed protocols for soft X-ray absorption spectroscopy (sXAS), soft X-ray emission spectroscopy (sXES), and resonant inelastic X-ray scattering (RIXS) experiments, which are inherently elemental-sensitive probes of the transition-metal 3d and anion 2p states in battery compounds. We provide the details on the experimental techniques and demonstrations revealing the key chemical states in battery materials through these soft X-ray spectroscopy techniques.

Here, we present a protocol for typical experiments of soft X-ray absorption spectroscopy (sXAS) and resonant inelastic X-ray scattering (RIXS) with applications in battery material studies.

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid ...

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 ...

Preparation of Graphene Liquid Cells for the Observation of Lithium-ion Battery Material

In this work, we introduce the preparation of graphene liquid cells (GLCs), encapsulating both electrode materials and organic liquid electrolytes between two graphene sheets, and the facile synthesis of one-dimensional nanostructures using electrospinning. The GLC enables in situ transmission electron microscopy (TEM) for the lithiation dynamics of electrode materials. The in situ GLC-TEM using an electron beam for both imaging and lithiation can utilize not only realistic battery electrolytes, but also the high-resolution imaging of various morphological, phase, and interfacial transitions.

Here, we present a protocol for the fabrication and preparation of a graphene liquid cell for in situ transmission electron microscopy observation, along with a synthesis of electrode materials and electrochemical battery cell tests.

In this work, we introduce the preparation of graphene liquid cells (GLCs), encapsulating both electrode materials and organic liquid electrolytes between ...

Zinc-Sponge Battery Electrodes that Suppress Dendrites

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