Name: focused ion beam fabrication of lipon-based solid-state lithium-ion nanobatteries for in situ testing
Uploaded: 2018-03-07T12:30:00.000+00:00
Duration: 10 min 58 s
Description: Watch this Scientific Journal Video about Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing at JoVE.com

The authors acknowledge funding support for the development of all-solid-state batteries and in situ FIB and TEM holder development by U.S. Department of Energy, Office of Basic Energy Sciences, under award number DE-SC0002357. The collaboration with national laboratories is made possible with partial support of the Northeastern Centre for Chemical Energy Storage, an Energy Frontier Research Centre funded by the U.S. Department of Energy, Office of Basic Energy Sciences under the award number DE-SC0001294. This research used resources of the Center for Functional Nanomaterials, which is a U.S. DOE Office of Science Facility, at Brookhaven National Laboratory under Contract No. DE-SC0012704. This work was performed in part at the San Diego Nanotechnology Infrastructure (SDNI), a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the National Science Foundation (Grant ECCS-1542148). FIB work was performed in part at the UC Irvine Materials Research Institute (IMRI), using instrumentation funded in part by the National Science Foundation Center for Chemistry at the Space-Time Limit (CHE-082913). We thank Nancy Dudney, Oak Ridge National Laboratory for providing us the thin-film batteries. J.L. acknowledges support from the Eugene Cota-Robles Fellowship Program and D.S is thankful to SERB, India for Ramanujan Fellowship (SB/S2/RJN-100/2014).

1. Preparation of Sample and System
<ol>
	<li>Attain a complete thin film battery consisting of an Al2O3 substrate (500 &#181;m thick), a gold cathode current collector (100 - 150 nm thick, DC sputtered), a LiCoO2 cathode (2 &#181;m thick, RF sputtered), a LiPON electrolyte (1 &#181;m thick, RF sputtered), an amorphous silicon anode (80 nm thick, RF&#160;sputtered), and a Cu anode current collector (100 nm, DC sputtered)16,17.</li>
	<li>Mount a complete thin film battery on a 25-mm diameter aluminum SEM stub, and use a copper tape to electrically connect the cathode current collector to the SEM stub to minimize charging effects.</li>
	<li>Prior to pumping down the chamber, confirm a low-noise electrical pathway exists to the copper grid, which the nanobattery will be mounted on and will serve as the conductive pathway to the cathode (Figure 1).
	<ol>
		<li>Connect the cathode lead to the stage through a shielded electrical feedthrough, as is present in systems equipped for electron beam induced current (EBIC) measurements with the appropriate connection type. Internally, connect the feedthrough to the stage with a shielded wire with an exposed tip; the method of securing the exposed wire tip will depend on the sample stage type, and, here, it is held in place by an unused stage set screw.</li>
		<li>Alternatively, and depending on the configuration of the grounding circuit of the instrument&#39;s stage, connect the cathode lead of the potentiostat to the stage ground using a BNC cable as shown in Figure 1.</li>
		<li>Perform the low-current noise test using the potentiostat in constant current mode. Apply the current with which in situ cycling is to be performed, and observe the accuracy and precision of the measured current. 
		NOTE: Using the configuration described in 1.3.1, a measured current of 1 pA &#177; 0.1 pA was achieved.</li>
	</ol>
	</li>
	<li>Similarly, create a conductive pathway from the micromanipulator tip to the outside of the probe by connecting the anode lead of the potentiostat to the micromanipulator ground using a BNC cable or an alligator clip as shown in Figure 1.
	<ol>
		<li>As in step 1.3.3, perform the low-current noise test using the potentiostat in constant current mode. 
		NOTE: Using the connections described in step 1.4, the minimum stable current achieved was 10 pA &#177; 1 pA, due to unshielded grounds connected to the micromanipulator.</li>
	</ol>
	</li>
</ol>
2. Lift-out of the Nanobattery
<ol>
	<li>Load the sample into the SEM/FIB chamber and pump down to system specified high vacuum (&#8804;10-5 mbar) before turning on the electron beam and ion beam imaging.</li>
	<li>Focus the electron beam on the thin film battery surface and determine the eucentric height using standard SEM/FIB procedures1.</li>
	<li>Tilt the sample such that the ion beam is normal to the battery surface (here 52&#176; sample tilt), and deposit a 1.5 to 2 &#181;m thick layer of FIB-deposited organometallic platinum on the top current collector of the thin-film battery using an ion beam current of around 0.3 nA and dwell time of 200 ns over an area of 25 x 2 &#181;m (Figure 2).</li>
	<li>Set ion beam voltage to 30 kV and ion beam dwell time to 100 ns for the remainder of the experimental protocol.</li>
	<li>Use a step-pattern cross-sectional FIB milling option, as provided in the FIB software, to expose the nanobattery stack around the Pt-deposit, as in TEM lamella preparation1. Select a milling current &#8804;2.8 nA. Input a mill depth extending at least 1 &#181;m beneath the active thin film battery (Z = 5 &#181;m in this case), a cross-sectional width (X) of 25 &#181;m and a cross sectional height (Y) of 1.5 x Z (here, Y = 7.5 &#181;m). Afterwards, the battery cross-section is exposed, to be viewed in SEM (here, the electron beam is 52&#176; from surface normal) as in Figure 3. 
	NOTE: The actual milled depth is thin film battery dependent.</li>
	<li>Use a cross-section cleaning procedure, provided in the FIB software, where the ion beam incrementally rasters closer to the surface being cleaned, with an ion beam current &#8804;0.3 nA to clean off re-deposited material and clearly expose the layered structure (Figure 3).</li>
	<li>Perform a series of rectangle under-cuts (also called J-cuts or U-cuts) at a stage tilt of 0&#176; and beam current &#8804;2.8 nA to isolate the majority of the nanobattery2. Make under-cuts consisting of i) a lower rectangle 0.5 x 25 &#181;m below the Au current collector onto the Al2O3 substrate, ii) a vertical rectangle 0.5 &#181;m wide (X) and through the entirety of the nanobattery thickness (Y), and iii) a vertical rectangle 0.5 &#181;m wide (X) and with a height less than the nanobattery thickness (Y - 2.5 &#181;m) around the Pt-coated nanobattery as in Figure 4a. These three under-cuts should be performed in parallel mode (simultaneously milled), to prevent re-deposition of material within the under-cut regions.</li>
	<li>Rotate the sample 180&#176; and perform the same horizontal undercut as in step 2.5. This isolates the bottom and sides of the nanobattery except for the remaining connected region.</li>
	<li>Rotate the sample 180&#176;. Insert the micromanipulator to the park position specified in the control software, then slowly bring it in contact with the nanobattery using the x-y-z movement of the software.</li>
	<li>Fix the micromanipulator to the Pt region on top of the nanobattery by ion-beam depositing 0.5 &#181;m thick Pt using a 30 keV ion beam with a current of 10 pA over an area of 2 x 1 &#181;m.</li>
	<li>Ion mill the remaining connected portion of the nanobattery with a beam current around 1 nA, and raise the nanobattery vertically with the micromanipulator (Figure 4b).</li>
	<li>Mount the nanobattery on a Cu FIB lift-out grid with 2 &#181;m thick ion-beam deposited Pt using a 30 keV ion beam with a current of 0.28 nA over an area of 10 x 5 &#181;m.</li>
	<li>Ion mill away the connection between the micromanipulator and nanobattery using a 30 keV ion beam with a current of 0.28 nA over an area of 1 x 1 &#181;m to a depth of 2 &#181;m, leaving a freestanding section attached to the Cu grid (Figure 5)1. 
	NOTE: The Cu lift-out grid provides a flat base for mounting the nanobattery as well as serving as a conductive pathway between the stage and the nanobattery.</li>
</ol>
3. Cleaning and Cycling the Nanobattery
<ol>
	<li>Tilt the sample such that the ion beam is normal to the battery surface and use a cross-sectional cleaning procedure (see step 2.4) to remove re-deposited material over a 5 &#181;m wide section of the nanobattery near the Cu grid, leading to a clear view of individual layers of the nanobattery (Figure 6a). 
	NOTE: Re-deposited material from previous milling steps must be removed from the grid-mounted nanobattery to expose the electrochemically active core of the nanobattery and prevent shorting.</li>
	<li>Deposit 500 nm thick FIB-Pt using a 30 keV beam with a current of 0.1 nA over an area of 1 x 2 &#181;m to create an electrical contact between the cathode current collector and the metallic grid, which is electrically connected to the stage (Figure 6b).</li>
	<li>Tilt the sample to 0&#176; and, using an ion beam current of 1 nA, make a rectangular cut 3 &#181;m wide and deep enough (Z ~ 2 &#181;m) to completely remove the anode current collector and electrolyte, isolating the anode from the Cu grid (Figure 6c).</li>
	<li>Use the cross-section cleaning procedure (see step 2.4) with an ion beam current around 0.1 nA to remove the re-deposited material around all sides of the nanobattery cross-section until all the individual layers are distinctly visible as shown in Figure 6d.</li>
	<li>Insert the micromanipulator to the park position and, using the control software, bring the micromanipulator in contact with the Pt above the anode current collector. Ion beam deposit 0.2 &#181;m thick Pt using a 30 keV ion beam with a current of 10 pA over an area of 2 x 1 &#181;m to &#34;weld&#34; connect the micromanipulator and current collector ( Figure 6d)1.</li>
	<li>Run the potentiostat in galvanostatic cycling mode. Current parameters used depend on the ultimate cross-sectional area of the fabricated nanobattery and desired C-rate, but will generally be on the order of a few nA. We select charge and discharge currents such that the current density is on the order of tens of &#181;A/cm2. For LiCoO2-based thin film batteries, the voltage range is 2.0 and 4.2 V.</li>
</ol>

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B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lithium+silicon+tin+oxynitride+(LiySiTON):+high-performance+anode+in+thin-film+lithium+ion+batteries+for+microelectronics.">Lithium silicon tin oxynitride (LiySiTON): high-performance anode in thin-film lithium ion batteries for microelectronics.</a> J. Power Source. 81, 27-32 (1999).</li><li>Ziegler, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SRIM-2003.">SRIM-2003.</a> Nucl. Instrum. Methods Phys. Res. 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We have nothing to disclose.

As demonstrated by our results, the technique described produces electrochemically active nanobatteries lifted out from a larger thin-film battery. Such techniques have enabled both ex situ and in situ STEM/EELS characterization of the buried interfaces by galvanostatically biasing the nanobattery. This allows unprecedented high-resolution characterization of quantitative chemical phenomena linked to the electrochemical state of charge. However, to achieve these results, a number of specific obstacles must be overcome.
Before beginning FIB processing, constant current testing should be conducted to ensure that there is a low-noise electrical pathway to the cathode and anode of the nanobattery. Cathode-side testing may be performed with the FIB chamber vented. Before pumping down the chamber for nanobattery fabrication, the positive terminal should be connected as if performing the experiment (either through a vacuum feedthrough or stage ground), and the negative terminal connected directly to the stage. Note that if using the touch alarm as a stage connection, the touch alarm capability of the instrument may be disabled, and the connection should only be made when no further tilting of the stage is necessary. However, here the test will require the system to be under vacuum, and the current will pass through both the micromanipulator and the stage circuit. The micromanipulator can be electrically adhered with Pt to the copper grid for constant current noise tests. If current resolution issues persist, contact your vendor for information on how to decouple the stage from the system ground.
For this technique to work, it is critical to use the provided ion beam specifications to minimize damage to the solid-electrolyte LiPON. LiPON is highly sensitive to prolonged exposure to (i) humid atmospheric conditions, (ii) electron beam, and (iii) ion beams. Hence the solid-state nanobattery fabrication process requires minimization of exposure to all three of these conditions. Pre- and post-fabrication exposure to atmospheric conditions should be absolutely minimized. The in situ FIB cycling process described was developed as a solution to minimize this exposure. During and after fabrication, electron beam imaging should be limited, as it damages the solid-electrolyte. Similarly, ion beam imaging should also be limited to avoid degradation of the electrolyte and other active components as well. The specific milling files and times are based on the equipment outlined in the table of materials/equipment for specific reagents, equipment, and manufacturers; this may vary between FIB instruments, and modifications may be required when using another instrument.
Of all parameters in the FIB fabrication of a nanobattery, the most critical considerations are the use of low beam current and dwell time to minimize damage14. Whenever required, imaging is performed with electrons at low pixel dwell times and with the ion beams at lower beam current (usually in pA) and low dwell time (100 ns). Most of the time, high dwell time electron beam imaging produces visible changes on the LiPON electrolyte. Figure 7a shows an undamaged LiPON and further imaging with an electron beam induces damage to the LiPON layer as shown in Figure 7b. This damage is irreversible resulting in a contrast change and will render the nanobattery electrochemically inactive.
Further, for electrochemical cycling, proper care must be taken to make electrical contact between the cathode current collector and the grid properly (Figure 6b). It is similarly important to maintain the micromanipulator contact to the anode (Figure 6); as seen in Figure 8a, at around 150 s, a spike in the electrochemical data corresponds to a vibration induced contact issue with the anode. Given the potential for instability of the micromanipulator-anode contact, the in situ testing time is minimized by limiting the nanobattery capacity, in turn reducing the charging time.
If the voltage profile is not consistent with the thin film battery, the cleaning procedure is repeated as there is likely some re-deposition causing shorting issues (Figure 10). The anode isolation step in particular is a large source of re-deposited material. This cleaning procedure decreases the nanobattery cross-section, so the current density should be corrected accordingly. It is noted that ion beam damage cannot be completely avoided and it is limited to between a few nm to a maximum of 25 nm into the surface, as calculated from ion scattering simulations SRIM program for 30 keV Ga+ into the electrode materials18. Low energy processing can reduce the damage to a large extent19. The FIB process demonstrated here is unique, and fabrication, manipulation, and in situ testing of nanodevices is enabled by FIB-SEM dual beam systems. It is possible to extend the process to any other battery chemistries and other nanoscale devices.
It is important to note that the specific parameters provided in this protocol may not directly transfer well to alternate electrochemical systems. LiPON was determined to be sensitive to thermal effects from the ion beam under high scanning rates. However, other electrolytes may suffer from other sensitivities. Similarly, although the material system tested in this protocol showed good electrochemistry after Ga+ ion milling, other materials systems may be more susceptible to ion straggle and implantation. As such, more exploration of the parameter space may be required for alternate material systems. More sensitive materials such as sulfides may perform poorly after ion milling, though this area of research is largely unexplored with advanced characterization techniques. Realistically, these parameters will translate to most material systems of interest, as modern solid electrolytes are generally crystalline and more robust than LiPON. Despite these potential limitations, the technique will be applied to new material systems, offering the potential to discover alternate interfacial phenomena, ultimately uncovering impedance mechanisms. A natural follow-up to this technique is the observation of electrochemical cycling in the TEM. This has been performed on the system described in this protocol, and uncovered previously unseen behavior at these interfaces. This technique will enable the observation of alternate forms of impedance.

Focused ion beams (FIB) have been used chiefly for transmission electron microscopy (TEM) specimen preparation and circuit editing1,2. Nanofabrication using FIB has progressed significantly during the last two decades with much focus on semiconductor materials3. Despite its importance to scientific advances, major concerns with FIB techniques remain, including surface damage, re-deposition, and preferential sputtering due to high current density4,5. There have been several articles on FIB damaging bulk materials during the preparation of TEM specimens and several methods to reduce this damage have been proposed6,7,8,9. However, FIB fabrication of active devices that consist of multiple layers with different functionality is still limited.
For solid-state devices, especially in the field of energy storage, interfaces play a crucial role, and the solid-solid interface is most often seen as a dominant source of impedance10. These interfaces are particularly difficult to characterize, due to a combination of their buried nature and data convolution in the presence of multiple interfaces in a single device. The fabrication of fully solid-state nanobatteries is critical to probe and understand the dynamic nature of these interfaces, which ultimately impact the electrochemical processes in batteries. Thin film batteries based on lithium phosphorous oxynitride (LiPON) were demonstrated more than two decades ago and are currently commercialized11. Although FIB fabrication of electrochemically active nanobatteries from a thin film battery is critical for enabling in situ evaluation of interfaces, most attempts to fabricate nanobatteries using FIB fail to retain electrochemical activity due to short-circuiting12. Initial attempts at in situ cycling thinned only a small portion of the nanobattery, to observe the lithium distribution by electron holography13.
More recent work has demonstrated the successful FIB fabrication of electrochemically active nanobatteries, which enabled both ex situ and in situ scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) characterization of interfacial phenomenon14,15. Important FIB fabrication parameters that help to retain electrochemical activity have been indicated by Santhanagopalan et al.14, and a detailed protocol is presented in this manuscript. This procedure is based on a model LiCoO2/LiPON/a-Si battery, but will ultimately enable the exploration of further thin film battery chemistries.

<table><tbody><tr><td>Biologic SP-200 Potentiostat</td><td>Biologic Science Instruments</td><td>SP-200</td><td>Ultra Low Current&amp;nbsp; Option needed for pA current resolution</td></tr><tr><td>FEI Scios DualBeam FIB/SEM</td><td>FEI</td><td></td><td>Current noise improves with a shielded stage feedthrough</td></tr><tr><td>SEM Stub: Large &amp;Oslash;25.4mm x 9.5mm pin height</td><td>Ted Pella</td><td>16144</td><td>Or equivalent</td></tr><tr><td>PELCO Colloidal Silver Paste, Conductive</td><td>Ted Pella, Inc.</td><td>16032</td><td>Or equivalent</td></tr><tr><td>PELCO&amp;reg;&amp;nbsp;FIB Lift-Out TEM Grids</td><td>Ted Pella</td><td>10GC04</td><td>Or equivalent</td></tr></tbody></table>

focused ion beam fabrication of lipon-based solid-state lithium-ion nanobatteries for in situ testing

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of lithium-ion (Li-ion) batteries. However, a number of setbacks prevent their integration into commercial devices. The main limiting factor is due to nanoscale phenomena occurring at the electrode/electrolyte interfaces, ultimately leading to degradation of battery operation. These key problems are highly challenging to observe and characterize as these batteries contain multiple buried interfaces. One approach for direct observation of interfacial phenomena in thin film batteries is through the fabrication of electrochemically active nanobatteries by a focused ion beam (FIB). As such, a reliable technique to fabricate nanobatteries was developed and demonstrated in recent work. Herein, a detailed protocol with a step-by-step process is presented to enable the reproduction of this nanobattery fabrication process. In particular, this technique was applied to a thin film battery consisting of LiCoO2/LiPON/a-Si, and has further been previously demonstrated by in situ cycling within a transmission electron microscope.

A representative solid-state Li-ion nanobattery fabrication process is shown step-by-step in the protocol referencing Figures 1-7.
Figure 8 shows in situ testing of the electrochemical charging profiles of two cells that were fabricated. Both profiles clearly show a 3.6 V plateau corresponding to LiCoO2-Si full cell chemistry and oxidation of Co3+ &#8594; Co4+. Cell-1 (Figure 8a) was tested at a lower current density (50 &#181;A/cm2) limiting the charge capacity to 12.5 &#181;Ah/cm2. Cell-2 (Figure 8b) presents a charging profile at a higher current density, 1.25 mA/cm2, that was limited by the upper cut-off voltage of 4.2 V. The capacity recorded was about 105 &#181;Ah/cm2, close to the theoretical capacity of Cell-2 (110 - 120 &#181;Ah/cm2). The first discharge capacity of the nanobatteries has been poor while the subsequent cycle capacities (both charge and discharge) were limited due to the first cycle irreversibility. The discharge process of nanobatteries is still not optimized, however, a representative charge-discharge profile at a current density of 60 &#181;A/cm2 is presented in Figure 9. The charge capacity was limited to 30 min and the discharge was limited to 2 V, and it is evident that the reversibility is about 35%. Though the reversibility is a lot better than what is reported in the literature14, further optimization is necessary.
If the voltage profile is not consistent with the thin film battery chemistry, this is likely due to either beam damage or shorting from re-deposited material. Figure 10 shows a voltage profile consistent with shorting where the voltage is constant and proportional to the applied current. The ion-beam image confirms that there is re-deposited material along the edge. The micromanipulator must be removed and further cross-sectional cleaning steps are needed to remove this material. This cleaning procedure decreases the nanobattery cross-section, so the current density should be corrected accordingly.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56259/56259fig1.jpg" /> 
Figure 1: Electrical connection schematic. A potentiostat is connected to the FIB nanobattery via external connections: 1) the negative terminal of the potentiostat to the disconnected ground of the micromanipulator needle; 2) the cathode side to either an electrically shielded vacuum feedthrough or a direct connection to the stage ground such as a touch alarm circuit (shown). Internal connections are made between the tip of the micromanipulator and the anode, and between the cathode and stage through a copper TEM lift-out grid. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56259/56259fig1large.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/56259/56259fig2.jpg" /> 
Figure 2: Pt deposition. SEM image of the Pt protective cap deposited on the thin film battery surface to avoid damage and making contact. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56259/56259fig2large.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/56259/56259fig3.jpg" /> 
Figure 3:&#160;Nanobattery cross-section. SEM images of the nanobattery lamella after cross-sectional cutting at (a) 52&#176; cross-section view and (b) and 0&#176; top view. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56259/56259fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/56259/56259fig4.jpg" /> 
Figure 4:&#160;Nanobattery liftout. Ion-beam images of (a) the lamella with under-cut and (b) lift-out of the isolated nanobattery by the micromanipulator. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56259/56259fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/56259/56259fig5.jpg" /> 
Figure 5:&#160;Nanobattery mounting. (a) Ion-beam and (b) SEM image of welding the lifted nanobattery to the copper TEM grid. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56259/56259fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/56259/56259fig6.jpg" /> 
Figure 6:&#160;Nanobattery cleaning. Ion-beam images of (a) cleaning one of the nanobattery cross-sections, (b) electrically connecting the grid and cathode current collector by Pt deposition, (c) cut to isolate anode from the TEM grid, and (d) cleaning the cross-section of the front, back, and sides to remove all re-deposited material. Final contact is made to the anode using the micromanipulator for biasing. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56259/56259fig6large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/56259/56259fig7.jpg" /> 
Figure 7:&#160;Nanobattery damage. SEM images of a nanobattery cross-section with (a) undamaged LiPON layer and (b) imaging at higher magnification induced damage in the LiPON layer indicated by the circle. High dwell time electron beam imaging produces visible changes in the LiPON electrolyte. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56259/56259fig7large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 8" class="xfigimg" src="/files/ftp_upload/56259/56259fig8.jpg" /> 
Figure 8:&#160;Nanobattery charging data. FIB fabricated nanobattery electrochemical charging profile at different current densities with (a) the capacity limited to 12.5 &#181;Ah/cm2 and (b) the voltage limited to a 4.2 V cut-off. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56259/56259fig8large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 9" class="xfigimg" src="/files/ftp_upload/56259/56259fig9.jpg" /> 
Figure 9: Nanobattery cycling profile. FIB fabricated nanobattery electrochemical charging and discharging profiles at a current density of 60 &#181;A/cm2. <a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56259/56259fig9large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 10" class="xfigimg" src="/files/ftp_upload/56259/56259fig10.jpg" /> 
Figure 10: Shorted nanobattery. (a) Voltage profile of a nanobattery that had not been cleaned properly resulting in shorting from re-deposited material and (b) the cross sectional ion-beam image.&#160;<a href="https://cloudflare-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/56259/56259fig10large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing at JoVE.com

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

A protocol for the fabrication of electrochemically active LiPON-based solid-state lithium-ion nanobatteries using a focused ion beam is presented.

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of ...

focused-ion-beam-fabrication-lipon-based-solid-state-lithium-ion

Nanyang Technological University

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JoVE Journal

Engineering

10.1K Views.  University of California San Diego. A protocol for the fabrication of electrochemically active LiPON-based solid-state lithium-ion nanobatteries using a focused ion beam is presented.

Video: Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

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 ...

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 ...

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 ...

Synthesis of Ionic Liquid Based Electrolytes, Assembly of Li-ion Batteries, and Measurements of Performance at High Temperature

The chemical instability of the traditional electrolyte remains a safety issue in widely used energy storage devices such as Li-ion batteries. Li-ion batteries for use in devices operating at elevated temperatures require thermally stable and non-flammable electrolytes. Ionic liquids (ILs), which are non-flammable, non-volatile, thermally stable molten salts, are an ideal replacement for flammable and low boiling point organic solvent electrolytes currently used today. We herein describe the procedures to: 1) synthesize mono- and di-phosphonium ionic liquids paired with chloride or bis(trifluoromethane)sulfonimide (TFSI) anions; 2) measure the thermal properties and stability of these ionic liquids by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA); 3) measure the electrochemical properties of the ionic liquids by cyclic voltammetry (CV); 4) prepare electrolytes containing lithium bis(trifluoromethane)sulfonamide; 5) measure the conductivity of the electrolytes as a function of temperature; 6) assemble a coin cell battery with two of the electrolytes along with a Li metal anode and LiCoO2 cathode; and 7) evaluate battery performance at 100 &#176;C. We additionally describe the challenges in execution as well as the insights gained from performing these experiments.

Here, we describe protocols to prepare phosphonium-based ionic liquid and lithium bis(trifluoromethane)sulfonimide salt electrolytes, and assemble a non-flammable and high temperature functioning lithium-ion coin cell battery.

The chemical instability of the traditional electrolyte remains a safety issue in widely used energy storage devices such as Li-ion batteries. Li-ion ...

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 ...

Chemistry

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 ...

Nanoscale Characterization of Liquid-Solid Interfaces by Coupling Cryo-Focused Ion Beam Milling with Scanning Electron Microscopy and Spectroscopy

Physical and chemical processes at solid-liquid interfaces play a crucial role in many natural and technological phenomena, including catalysis, solar energy and fuel generation, and electrochemical energy storage. Nanoscale characterization of such interfaces has recently been achieved using cryogenic electron microscopy, thereby providing a new path to advancing our fundamental understanding of interface processes.
This contribution provides a practical guide to mapping the structure and chemistry of solid-liquid interfaces in materials and devices using an integrated cryogenic electron microscopy approach. In this approach, we pair cryogenic sample preparation which allows stabilization of solid-liquid interfaces with cryogenic focused ion beam (cryo-FIB) milling to create cross-sections through these complex buried structures. Cryogenic scanning electron microscopy (cryo-SEM) techniques performed in a dual-beam FIB/SEM enable direct imaging as well as chemical mapping at the nanoscale. We discuss practical challenges, strategies to overcome them, as well as protocols for obtaining optimal results. While we focus in our discussion on interfaces in energy storage devices, the methods outlined are broadly applicable to a range of fields where solid-liquid interface play a key role.

Cryogenic Focused Ion Beam (FIB) and Scanning Electron Microscopy (SEM) techniques can provide key insights into the chemistry and morphology of intact solid-liquid interfaces. Methods for preparing high quality Energy Dispersive X-ray (EDX) spectroscopic maps of such interfaces are detailed, with a focus on energy storage devices.

Physical and chemical processes at solid-liquid interfaces play a crucial role in many natural and technological phenomena, including catalysis, solar ...

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.

Focused Ion Beam Fabrication of LiPON-based Solid-state Lithium-ion Nanobatteries for In Situ Testing

Summary

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Chapters in this video

Construction and Testing of Coin Cells of Lithium Ion Batteries

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

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

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

Synthesis of Ionic Liquid Based Electrolytes, Assembly of Li-ion Batteries, and Measurements of Performance at High Temperature

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

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

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

Nanoscale Characterization of Liquid-Solid Interfaces by Coupling Cryo-Focused Ion Beam Milling with Scanning Electron Microscopy and Spectroscopy

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