Directly Formed Alucone on Lithium Metal for High Performance Li

Subscriber access provided by READING UNIV

Article

Directly Formed Alucone on Lithium Metal for High Performance Li Batteries and Li-S Batteries with High Sulfur Mass-loading Lin Chen, Zhennan Huang, Reza Shahbazian-Yassar, Joseph A Libera, Kyle Klavetter, Kevin R. Zavadil, and Jeffrey W. Elam ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b15879 • Publication Date (Web): 30 Jan 2018 Downloaded from http://pubs.acs.org on January 31, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

ACS Applied Materials & Interfaces is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Applied Materials & Interfaces

Directly Formed Alucone on Lithium Metal for High Performance Li Batteries and Li-S Batteries with High Sulfur Mass-loading Lin Chen1,2, Zhennan Huang3, Reza Shahbazian-Yassar3, Joseph A. Libera1, Kyle C. Klavetter2,4, Kevin R. Zavadil2,4, and Jeffrey W. Elam* 1,2 1) Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439, USA 2) Joint Center for Energy Storage Research (JCESR), Argonne National Laboratory, Argonne, IL 60439, USA 3) Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, USA 4) Materials Science and Engineering, Sandia National Laboratories, Albuquerque, NM 87185, USA * Corresponding author: [email protected]

Abstract: Lithium metal is considered the “holy grail” of next-generation battery anodes. However, severe parasitic reactions at the lithium-electrolyte interface deplete the liquid electrolyte, and the uncontrolled formation of high surface area and dendritic lithium during cycling cause rapid capacity fading and battery failure. Engineering a dendrite-free lithium metal anode is therefore critical for the development of long-life batteries using lithium anodes. In this study, we deposit a conformal, organic/inorganic hybrid coating, for the first time, directly on lithium metal using molecular layer deposition (MLD) to alleviate these problems. This hybrid organic/inorganic film with high cross-linking structure can stabilize lithium against dendrite growth, and minimize side reactions, as indicated by scanning electron microscope. We discovered that the alucone coating yielded several times longer cycle life at high current rates compared to the uncoated lithium, and achieved a steady Coulombic efficiency of 99.5%, demonstrating that the highly cross-linking structured material with great mechanical properties and good flexibility can effectively suppress dendrites formations. The protected Li was further evaluated in lithiumsulfur (Li-S) batteries with high sulfur mass loading of ~5 mg/cm2. After 140 cycles at a high current rate of ~1 mA/cm2, the alucone-coated Li-S batteries delivered the capacity of 657.7 mAh/g, 39.5% better than the bare lithium-sulfur battery. The report originally suggests that the flexible coating with high cross-linking structure by MLD is effective to enable lithium protection and offers a very promising avenue for improved performance in the real applications of Li-S batteries. 1 ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 22

Keywords: molecular layer deposition, direct coating, lithium metal batteries, high mass-loading, lithium sulfur batteries

Introduction Rechargeable batteries with high energy density, long cycle life, and excellent safety are needed for advanced portable electronic devices. More importantly, such batteries would facilitate the wide-scale adoption of electric vehicles to reduce our dependency on fossil fuels and reduce carbon emissions for a sustainable future.1-8 The graphite anode used in conventional lithium ion (Li-ion) batteries virtually eliminates the hazards posed by lithium dendrite formation, but the amount of intercalated lithium ions in graphite limits the theoretical capacity to only ~370 mAh/g and cannot meet societal needs.5, 9-11 Therefore, developing higher energy density anodes is of paramount importance for next-generation Li-ion batteries for electric vehicles and renewable energy storage.12-13

Lithium metal has been considered as the ideal anode for lithium batteries since the first reports in the 1970’s due to the extremely high theoretical capacity (3,860 mAh/g), very low electrochemical potential (-3.04 V versus standard hydrogen electrode), and low density (0.534 g/cm3).14-19 However, key technical challenges prevent lithium anodes from commercial application. These include the non-planar electrodeposition of lithium upon cycling resulting in the growth of long, needle-like dendrites that can pierce the separator and short the cell producing catastrophic failure,20-21 and parasitic reactions between the lithium metal and the electrolyte leading to electrolyte depletion.22 These issues are applicable in lithium-metal sulfur (Li-S) batteries which are promising for electric vehicles because of the high theoretical energy density of sulfur (2500 Wh/kg).23 For instance, the sulfur cathode in Li-S batteries can form polysulfides as intermediate products during cycling, and these polysulfides can dissolve into the electrolyte and migrate to the anode where they react with Li metal and cause rapid capacity decay.4 Electrolyte depletion becomes acute in Li-S batteries because their commercial viability in electric vehicles demands a very low electrolyte volume to sulfur mass ratio (E/S, mL/g).24 As mentioned above, Li tends to electrodeposit with a rough, porous morphology exposing fresh lithium and consuming electrolyte with each charge-discharge cycle. 2 ACS Paragon Plus Environment

Page 3 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


In order to tackle these problems, researchers have pursued a number of strategies including: 1) electrolyte additives25-29 designed to form a stable, low-impedance solid electrolyte interphase (SEI) on the Li anode28 and minimize parasitic reactions;29 2) solid polymer electrolytes and high modulus separators30-32 that impart compressive forces to stabilize the lithium anode during deposition; 3) thin film coatings to serve as artificial SEI layers.33-36 These coatings must exhibit high ionic conductivity and low electrical conductivity to ensure lithium electrodeposition beneath the coating.34, 37 For instance, Yan et al. evaluated ultrathin hexagonal boron nitride (h-BN) and graphene coatings on Cu current collectors for lithium metal batteries (LMBs).21 These coatings increased the Coulombic efficiency (CE) of the LMBs due to their excellent chemical stability and great mechanical strength. One disadvantage to this approach is that the coated Cu must first be incorporated into a Li-Cu cell in order to deposit Li, after which the cell must be opened to harvest the Li-coated Cu electrode. Furthermore, the LMBs exhibited a CE of only ~95%, insufficient for practical devices. In a different study, Archer et al. utilized a nanoparticle-based gel polymer as the electrolyte for LMBs.22 The nanoparticles in the polymer enabled crosslinking, which increases the modulus of the polymer electrolyte by several orders of magnitude. The authors also coupled their anode with intercalating cathodes for conventional Li-ion batteries. However, it is time consuming by taking multiple steps to get the synthesized polymer.

Molecular layer deposition (MLD) uses alternating exposures between precursor vapors and a surface to deposit thin films in an atomic layer-by-layer fashion, similar to atomic layer deposition (ALD), but yields organic films or organic/inorganic hybrid films.38-39 For instance, alternating exposures to ethylene glycol (EG) and trimethyl aluminum (TMA) yield alucone films that are an order of magnitude more flexible and soft compared to ALD Al2O3,40 while retaining the desirable attributes of conformality, continuity, and sub-nanometer precision. Previously, MLD alucone was used to coat sodium metal anodes,41 but there has not yet been a report of MLD alucone on lithium anodes. Herein we propose a versatile approach by directly forming highly cross-linked organic/inorganic alucone thin films with MLD on lithium metal, and evaluate the battery performance. Ethylene glycol was chosen as the precursor since EG is the monomer of polyethylene glycol (PEO), a stable polymer with good ionic conductivity that is widely used for solid state electrolytes.42 Thus, the deposited alucone actually consists of the PEO structure that is 3 ACS Paragon Plus Environment


Page 4 of 22

cross-linked to aluminum as the framework in the hybrid organic/inorganic material. As the electrolyte volume plays a critical role on lithium metal performance, in this work, we tested different electrolyte content for symmetric cells and Li-Cu cells and found that the ultrathin alucone coating not only stabilizes lithium metal anodes, but also dramatically extends the cycle life of lithium and provides a steady CE of ~99.5%. We also evaluated the alucone protected Li as an anode for high mass-loading Li-S batteries and observed 39.5% improvement on the capacity performance compared to bare Li in the electrolyte volume of 10 (E/S ratio).34 Further evaluation of electrolyte content (E/S = 5) had been performed for Li-S batteries and it also shows that alucone is an excellent protective material on lithium for improved performance.

Results and Discussion Synthesis and characterization of MLD alucone. Figure 1a shows a schematic diagram for the synthesis of hybrid organic-inorganic alucone films via MLD using trimethylaluminium (TMA) and ethylene glycol (EG).38 Detailed experimental procedures can be found in Methods. This diagram assumes that the starting surface is terminated with hydroxyl (OH) groups, which is characteristic of most metal oxide surfaces as well as metal surfaces that bear a native oxide. In the MLD process, TMA reacts with surface OH groups to form Al-O linkages and a methylterminated surface, and liberates methane gas. Next, EG reacts with the Al-CH3 groups to form alkoxy (Al-O-R) linkages and methane, and regenerating the hydroxyl-terminated surface. The alucone film continues to grow with each additional TMA/EG cycle, and crosslinking produced when TMA bridges neighboring R-OH groups provides great flexibility43 and good mechanical strength.44 Figure 1b presents our facile approach for directly coating alucone on lithium metal. The chemical structure of alucone after multiple MLD cycles inserted in this figure, as seen, is cross-linking. With the MLD coating cycle increasing, the cross-linking structure grows exponentially by one cycle.

4 ACS Paragon Plus Environment

Page 5 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a)

(b)

(c)

(d)

Figure 1. Schematic synthesis and characterization of alucone. (a) Schematic for first two cycles of alucone MLD beginning with a hydroxylated surface. (b) Facile MLD process directly coat alucone on lithium metal, forming highly cross-linking structured alucone on the lithium foil. (c) TEM image of MLD alucone film on 100 nm SiO2 nanospheres. (d) EDS mapping of MLD alucone film on 100 nm SiO2 nanospheres.

To characterize the alucone thin film prepared by MLD, we performed 100 alucone MLD cycles at 150 °C onto 100 nm SiO2 nanospheres to deposit a film of ~10 nm and performed transmission electron microscopy (TEM, Figure 1c). As we can see, the MLD alucone is uniform, smooth and 5 ACS Paragon Plus Environment


Page 6 of 22

conformal on the SiO2 nanospheres. Energy-dispersive X-ray spectroscopy (EDS) mapping was performed to measure the spatial distributions of Al, C, Si, and O. Figure 1d shows a composite image of these elemental distributions and demonstrates that the Al signal is most intense around the perimeter of the particle as expected for the MLD alucone film. Additional information is provided by elemental line scans in Figure S1, which clearly show O in the outer shell along with the Al and distributions of individual elements.

The alucone thicknesses on lithium reported in this paper are based on ellipsometric measurements of alucone films on silcon and TEM measurements of alucone films on silica nanoparticles. The reactivities of TMA and EG may be different on lithium as compared to silicon and silica, and this will affect the alucone nucleation and the alucone film thickness. However, our previous study of Al2O3 ALD on lithium using TMA and H2O via in situ quartz crystal microbalance (QCM) measurements revealed that nucleation lasted only 4-5 ALD cycles, after which the Al2O3 ALD on Li became very similar to that on conventional substrates such as silicon34. For this reason, we believe that the alucone thicknesses reported on lithium in this study are close to the stated values of ~3 and ~6 nm after 30 and 40 MLD cyles, respectively.

Li metal cycling stability during electrodeposition. Symmetric, Li∣Li coin cells were fabricated with and without alucone coatings in order to investigate the stability of the Li surfaces during sequential stripping/plating cycles. Figure 2a presents the voltage profiles measured at 1.0 mA/cm2 to a capacity of 1.0 mAh/cm2 using 10 μL electrolyte volume for both the coated and bare Li coin cells. The voltage profile for the alucone-coated Li is much more stable versus time compared to the bare lithium. In contrast, the bare lithium shows a higher polarization during the first ~10 cycles and the voltage is unstable. These voltage variations probably result from changes in surface morphology upon Li stripping/plating, which would produce a rough and thick solid electrolyte interphase (SEI) that continues to grow with each cycle as fresh Li is exposed. We speculate that the more stable voltage profile for the alucone-coated Li correlates with a stable and uniform SEI. The insets in Figure 2a show expanded views of the voltage profiles for the bare and coated Li coin cells at different periods. The overpotential of the bare Li cells increases with testing time, suggesting that the impedance was increasing due to electrolyte consumption and thicker SEI formation. Conversely, the smaller overpotentials for the alucone-coated Li indicate small 6 ACS Paragon Plus Environment

Page 7 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


impedance changes, and suggest that the electrolyte was preserved by the conformal alucone coating and SEI layer. During these measurements, the overpotential of the alucone-coated Li is consistently lower than bare Li, illustrating that the alucone coating creates a stable system for lithium anode operation. Even after the bare lithium failed with short circuit, indicated by a sudden voltage drop, at ~158 hours, the alucone protected Li maintained stable operation.

(a)

(b)

Figure 2. Cycling stability of Li electrodeposition in symmetric cells and SEM characterization. (a) Li stripping/plating in different symmetric cells with 10 μL carbonate electrolyte at 1.0 mA/cm2 up to capacity of 1.0 mAh/cm2. Alucone on Li is ~6 nm. (b) Li stripping/plating in different symmetric cells with only 5 μL carbonate electrolyte at 1.0 mA/cm2 up to capacity of 1.0 mAh/cm2. (c) SEM image of Li anode after 50 cycles in Li/Li symmetric cell with 20 μL carbonate electrolyte at 1.0 mA/cm2 up to capacity of 1.0 mAh/cm2. (d) SEM image of alucone-coated



Page 8 of 22

Li anode after 50 cycles in alucone-Li/alucone-Li symmetric cell with 20 μL carbonate electrolyte at 1.0 mA/cm2 up to capacity of 1.0 mAh/cm2. Scale bar: 10 μm.

We examined several different alucone thickness on Li and compared their cycling stability using symmetric cells, as shown in Supporting Figure S2. 30 cycles and 60 cycles of alucone correspond to ~3 nm and ~6 nm, respectively. Both alucone coatings were found to provide much better cycling stability compared to the uncoated Li anode, but the ~6 nm alucone coating yielded a slightly lower overpotential over the entire testing period. Thus, ~6 nm alucone was selected for all other measurements in this paper except where noted.

A recent study highlighted the need for high sulfur loadings and low electrolyte volumes in order for Li–S batteries to compete with conventional LIBs.24 Consequently, we studied the Li stripping/plating performance with and without the alucone coatings as a function of the electrolyte volume. Figure 2b and Figure S2 display voltage profiles for symmetric cells tested at a current density of 1.0 mA/cm2 to a capacity of 1.0 mAh/cm2 using 5 μL and 20 μL carbonate electrolyte, respectively. In both cases, the uncoated Li cell begins to exhibit voltage instability much sooner than the alucone-coated Li. In fact, the lifetime of the bare Li cells decreases with decreasing electrolyte volume, and this is consistent with our interpretation that cell failure is caused by consumption of the liquid electrolyte and associated short circuits. This problem is greatly reduced by the protective alucone coatings indicating that these coatings reduce the rate of electrolyte consumption.

Figure 2c and 2d show scanning electron microscope (SEM) images of bare Li metal and aluconecoated Li, respectively, after 50 charge-discharge cycles in symmetric cells using the same testing conditions as in Figure S2. The bare Li surface is extremely rough and porous and shows lithium dendrites (Figure 2c) while the protected Li is smooth and relatively featureless (Figure 2d). Higher resolution SEM images are shown in Figure S3. This observation argues that the conformal alucone protects the Li anode even after many cycles at a high current density of 1.0 mA/cm2. Moreover, the MLD alucone film promotes planar electrodeposition of the Li without forming dendrites. We note that the 1.0 mAh/cm2 charge/discharge capacity corresponds to the movement of ~5 μm Li during each charge or discharge compared to an MLD alucone thickness of only ~6 8 ACS Paragon Plus Environment

Page 9 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


nm. Evidently, the highly cross-linked MLD film possesses sufficient mechanical strength and flexibility to withstand these large and fast volume changes. It should be mentioned that aluconecoated Li can also improve the electrolyte wettability that can help with uniform Li stripping/plating processes as elaborated in our previous report.34

For batteries using lithium metal anodes, the Li continuously degrades the liquid electrolyte by parasitic chemical reactions and electrochemical reduction. Rough Li deposition and dendrite growth exacerbate the side reactions because fresh Li metal is exposed during every cycle. Coulombic efficiency (CE), calculated from the amount of lithium deposited onto the anode divided by the amount of lithium stripped in the same cycle, is an effective indicator of side reactions between the Li and electrolyte. Significant parasitic reactions produce a low CE, and vice versa. Thus, it can also be used to analyze SEI formation and stability. In order to calculate the CE on a cycle-by-cycle basis, we prepared asymmetric Li∣Cu coin cells incorporating both bare Li and alucone-coated Li.

(a)

(b)

(c)

(d)



Page 10 of 22

Figure 3. Coulombic efficiency and voltage profile of Li metal stripping/plating on Cu as the working electrode. (a) CE of Li electrodeposition on Cu with 20 μL ether electrolyte at 0.4 mA/cm2. (b) CE of Li electrodeposition on Cu with 20 μL ether electrolyte at 1.0 mA/cm2. (c) Voltage profile of Li/Cu and alucone-coated Li/Cu cells at 0.4 mA/cm2 for the second cycle. (d) EIS data for bare Li and ~6 nm alucone-coated Li paired with Cu as the working electrode in 20 μL ether electrolyte before cycling.

Figure 3a shows the CE versus charge/discharge cycles using a current rate of 0.4 mA/cm2. The CE is low for both the bare Li and alucone-coated Li cells during the first cycle, presumably due to side reactions between the Li and the electrolyte to form the SEI on both the Li and Cu electrodes. After several cycles, the CE reaches a stable value of ~99.5%. For the bare Li cell, this high CE value is sustained until the 54th cycle when the CE drops rapidly and the cell fails at ~60 cycles. This behavior is very similar to that of the Li∣Li symmetric cell (Figure 2a), and we attribute this to electrolyte consumption by a rough, dendritic Li metal surface. Evidently, the SEI layer on bare Li is not strong enough to accommodate the volume changes of Li,20 especially after growth of high modulus lithium dendrites. In contrast, the MLD alucone coating allows the CE of ~99.5% to persist for over 160 cycles, more than 3 times that of uncoated Li. We hypothesize that the highly cross-linked structure of the alucone film is sufficiently robust to endure the Li volume changes. Consequently, the SEI is stable, and this prevents rapid electrolyte consumption and promotes uniform and dendrite-free lithium electrodeposition.

To evaluate the effectiveness of MLD alucone protection at higher current rates, the Li-Cu cells were cycled at 1.0 mA/cm2 (Figure 3b). Under these conditions, the bare Li fails after only ~30 cycles due to the rough lithium deposition caused by fast Li stripping/plating at higher current rates. It is interesting to note that the CE measured for the alucone-coated Li cell is ~96% after 10 cycles and appeared to fluctuate between 10 and 53 cycles, after which it stabilized at ~98.5%. These fluctuations may result from the alucone becoming lithiated during cycling, since the lithiated alucone is expected to have a higher ionic conductivity than alucone, in analogy with lithiated Al2O3.34 At the relatively large current density of 1.0 mA/cm2, the driving force for lithium diffusion is huge while alucone does not have excellent ionic conductivity at room temperature to realize this process, leading to some Li loss within the coating and a relative low CE. As mentioned, alucone contains ether groups and should easily solvate Li+ to improve ionic conductivity in the amorphous phase, similar to PEO.15, 45 After the alucone becomes lithiated, the ionic conductivity 10 ACS Paragon Plus Environment

Page 11 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


should increase yielding a higher and more stable CE. At the high current density of 1.0 mA/cm2, the alucone-coated Li survived more than 130 cycles, ~4 times that of bare Li.

The voltage difference (hysteresis) between the stripping and plating plateaus within a chargedischarge cycle can provide information about the non-ideality of a battery. For instance, a larger hysteresis indicates a larger cell impedance and slower lithium ion diffusion. Figure 3c depicts the voltage hysteresis recorded during the second charge-discharge cycle for Li-Cu asymmetric coin cells prepared with and without the MLD alucone coating cycled at 0.4 mA/cm2 and using 20 µL electrolyte. The alucone coated Li has a much smaller voltage difference (~10 mV) in contrast to bare the Li (~20 mV). This suggests that the MLD alucone coating has a lower impedance than the SEI layer that forms on the bare Li surface during cycling. As discussed, we speculate that the highly crosslinking structure and ether functional groups (–CH2–CH2–O–) of the alucone film effectively solvate Li+ similar to PEO15 and provides efficient pathways for Li+ to diffuse.

The experiment was repeated using an electrolyte volume of only 10 µL to explore the cycling behavior under lean conditions. As shown in Figure S4, the alucone-coated Li still demonstrates much better stability, which does not degrade within 67 cycles, compared to initial failure of bare Li from the 18th cycle. These results are highly desirable for practical rechargeable batteries, such as Li-S batteries.

Electrochemical impedance spectroscopy (EIS) measurements of uncoated and coated Li paired with Cu in coin cells are displayed in Figure 3d. The semicircle at high frequency represents the resistance of charge transfer (Rct).46 Compared to uncoated Li, the alucone-coated Li has a larger Rct, indicating that alucone increases the electronic resistance. This is desirable for lithium protection because it prevents electrons from attacking the electrolyte,34, 47 and also induces the Li to redeposit underneath the alucone coating.

High mass-loading Li-S batteries with controlled electrolyte volume. In order to evaluate the performance of alucone-coated lithium in full cells, we prepared Li-S coin cells with high sulfur loading (~ 5 mg/cm2). As discussed above, the electrolyte content in practical Li-S batteries must 11 ACS Paragon Plus Environment


Page 12 of 22

be very low (i.e., E/S

Directly Formed Alucone on Lithium Metal for High Performance Li

Recommend Documents