Supplementary Information Layered reduced graphene … · Supplementary Information Layered reduced...

SUPPLEMENTARY INFORMATIONDOI: 10.1038/NNANO.2016.32

NATURE NANOTECHNOLOGY | www.nature.com/naturenanotechnology 1

Supplementary Information

Layered reduced graphene oxide with nanoscale interlayer gaps as stable

host for lithium metal anodes

Dingchang Lin, Yayuan Liu, Zheng Liang, Hyun-Wook Lee, Jie Sun, Haotian Wang, Kai

Yan, Jin Xie, Yi Cui.

Table of contents

Part I: Materials synthesis

Supplementary Figure 1.│Time evolution of spark reaction.

Supplementary Figure 2.│Time evolution of Li infusion into layered rGO film.

Part II: Lithiophilicity of the layered rGO film

Supplementary Figure 3.│Lithiophilicity of various carbon materials.

Supplementary Figure 4.│First-principles calculations on surface binding energy.

Supplementary Figure 5.│Capillary force at different scale and litiophilicity.

Part III: Characterizations on the materials

Supplementary Figure 6.│Brunauer–Emmett–Teller (BET) surface area

characterizations on GO/rGO.

Layered reduced graphene oxide with nanoscale interlayer gaps as a stable

host for lithium metal anodes

© 2016 Macmillan Publishers Limited. All rights reserved.

http://dx.doi.org/10.1038/nnano.2016.32

2 NATURE NANOTECHNOLOGY | www.nature.com/naturenanotechnology

SUPPLEMENTARY INFORMATION DOI: 10.1038/NNANO.2016.32

Supplementary Figure 7.│ X-ray photoelectron spectroscopy (XPS) Li 1s spectra

of Li foil and Li-rGO composite.

Supplementary Figure 8.│XPS survey characterizations on GO/rGO.

Supplementary Figure 9.│Raman spectroscopy characterizations on GO/rGO.

Supplementary Figure 10.│X-ray diffraction (XRD) characterizations.

Supplementary Figure 11.│Layered Li-rGO electrodes with different thickness.

Supplementary Figure 12.│Surface morphology of layered Li-rGO after cycled at

5 mA cm-2.

Supplementary Figure 13.│Layered Li-rGO electrode surface after 100

galvanostatic cycles.

Supplementary Figure 14.│Time evolution of Li deposition observed with in situ

TEM.

Supplementary Figure 15.│Ex situ SEM characterization on thickness variation.

Part IV: Electrochemical testing

Supplementary Figure 16.│Comparison on the voltage profiles at various current

density.

Supplementary Figure 17.│Long-cycle stabililty of layered Li-rGO electrode.

Supplementary Figure 18.│Electrochemical cycling performance with ether-based

electrolyte.

Supplementary Figure 19.│Electrochemical cycling of symmetric cells at 2 mA

cm-2.

Supplementary Figure 20.│High areal capacity cycling stability of layered Li-rGO

electrodes.





Supplementary Figure 21.│Electrochemical impedance spectroscopy

characterizations before cycling.

Supplementary Figure 22.│Electrochemical performance of the LCO/Li-rGO

cells.

Supplementary Figure 23.│Electrochemical performance of the LTO/Li-rGO

cells.

Supplementary Figure 24.│Battery cycling with limited Li amount.

Part V: Supplementary Movies

Supplementary Video 1.│Spark reaction on GO film.

Supplementary Video 2.│Li infustion into rGO film.

Supplementary Video 3.│Flexibility of Li-rGO film.

Supplementary Video 4.│In situ TEM movie of Li infusion with side view. The

video is played at 50 x the actual speed.

Supplementary Video 5.│In situ TEM movie of Li infusion with top view. The

video is played at 15 x the actual speed.

Supplementary Video 6. │ In situ TEM movie of dendritic Li deposition without a

host. The video is played at 50 x the actual speed.





Supplementary Figure 1. │Time evolution of spark reaction. Time-lapse images of the

spark reaction visualizing the detailed phenomenon of the reaction within 100 milliseconds.

The images of the reaction at different time of 0 ms (a), 20 ms (b), 40 ms (c), 60 ms (d),

80 ms (e), and 100 ms (f) were shown successively. The yellow arrow in a shows the initial

contact point between GO and molten Li, where the reaction initiated. The flame shown in

the images illustrates the possible H2 formation under the strong reduction condition in the

presence of molten Li and its combustion reaction with the trace amount of oxygen in the

glove box. This can be one of the reasons for the interlayer expansion of GO.





Supplementary Figure 2. │ Time evolution of Li infusion into layered rGO film. Time-

lapse images (a, 0s; b, 5s; c, 12s; d, 20s; e, 45s) of Li infusion process into the sparked-

rGO film. The edge of the sparked-rGO film was put in contact with the molten Li. Rapid

Li infusion can be observed where it took less than 1 minute for Li to spread across the

whole sparked-rGO surface.





Supplementary Figure 3. │ Lithiophilicity of various carbon materials. Surface

wetting of molten Li on different carbon materials, including CNT film (a,f), carbon fiber

paper (b,g), mesoporous carbon coated on Cu foil (c,h), electrospun carbon nanofiber (d,i)

and sparked-rGO film (e,j). For sparked-rGO film, the molten Li was rapidly infused into

the matrix with good wettability. In contrast, the other carbon materials showed relatively

large contact angle, indicating relatively poor Li surface wettability.





Supplementary Figure 4. │ First-principles calculations on surface binding energy.

First-principles calculations showing the binding energy between Li and bare graphene

surface (a), carbonyl (C=O) groups (b), alkoxy groups (C-O) (c), and epoxyl (C-O-C)

groups (d). The carbonyl and alkoxy groups show much stronger interaction with Li

compared to bare graphene surface.





Supplementary Figure 5. │ Capillary force at different scale and litiophilicity.

Schematic showing the effect of capillary force with different surface ‘lithiophilicity’

(‘lithiophobic’-left, ‘lithiophilic’-middle & right) and different interlayer gap dimension

(‘larger interlayer dimension’-middle, ‘nanoscale interlayer dimension’-right). It is known

that the capillary force on lyophobic surface will lower the liquid level while the lyophilic

surface will lift the liquid level. The height of the liquid level is inversely proportional to

the diameter, which means smaller spacing with lyophilic surface will give rise to higher

liquid level.





Supplementary Figure 6. │ Brunauer–Emmett–Teller (BET) surface area

characterizations on GO/rGO. N2 adsorption-desorption isotherms of the pristine GO

film (blue) and the sparked rGO film (red), from which the BET surface area was calculated

to be 8.0 m2 g-1 and 394.3 m2 g-1, respectively.





Supplementary Figure 7.│ X-ray photoelectron spectroscopy (XPS) Li 1s spectra of

Li foil and Li-rGO composite. The XPS Li 1s spectra of Li foil and Li-rGO composite

showing the signals of metallic Li (red), Li2O/LiOH (green) and Li2CO3 (blue).





Supplementary Figure 8.│XPS survey characterizations on GO/rGO. XPS survey

spectra of pristine GO (black) and sparked rGO (red). After spark reaction, significantly

increased C/O ratio can be observed, which indicates the removal of O-containing species

and the reduction of GO in the spark process.





Supplementary Figure 9. │ Raman spectroscopy characterizations on GO/rGO.

Raman spectra of pristine GO (black) and sparked rGO (red) films. The sparked rGO

showed lower D/G band ratio.





Supplementary Figure 10. │ X-ray diffraction (XRD) characterizations. XRD spectra

of pristine GO film (blue), sparked rGO (black) and Li-rGO composite (red). Pristine GO

showed a sharp peak at 2θ ~ 11°, which is typical for highly oxidized graphite with

remarkably increased interlayer spacing (d ~ 0.8 nm). The peak at 2θ ~ 11° disappeared for

sparked rGO, indicating the partial reduction of GO. A sharp peak corresponding to

metallic Li (110) can be observed for Li-rGO, indicating the successful infusion of Li into

the rGO matrix.





Supplementary Figure 11. │ Layered Li-rGO electrodes with different thickness.

SEM images of the Li-rGO electrodes with different thickness of ~50 μm (a,d), ~80 μm

(b,e), and ~200 μm (c,f). The magnified SEM images shown in d-f indicate consistent

layered structure with similar spacing despite the electrode thickness





Supplementary Figure 12. │ Surface morphology of layered Li-rGO after cycled at 5

mA cm-2. Low-magnification (a) and magnified (b) SEM images of the top surface of

layered Li-rGO electrode after 10 galvanostatic cycles with current density of 5 mA cm-2.

The stripping/plating capacity was fixed at 1 mAh cm-2. The images show relatively flat

surface, small quantity of Li can be observed on the top surface (b).





Supplementary Figure 13.│Layered Li-rGO electrode surface after 100 galvanostatic

cycles. a, SEM image of the layered Li-rGO electrode surface after 100 cycles with SEI

coverage. b, SEM image of the layered Li-rGO electrode surface after 100 cycles where

the region on the left of the red dash line has SEI coverage and that on the right has no SEI

coverage. c, SEM image of the layered Li-rGO electrode surface after 100 cycles without

SEI coverage. Part of SEI layer on the surface was removed gently by mechanical scratch

while the rest part left intact. The cell was cycled in symmetric configuration with layered

Li-rGO as the electrodes, at current density of 1 mA cm-2 with the capacity fixed at 1 mAh

m-2 for 100 cycles.





Supplementary Figure 14. │ Time evolution of Li deposition observed with in situ

TEM. a-e, Time evolution of Li deposition onto a substrate without stable host. Snapshots

at 0 s, 100 s, 200 s, 300 s and 350 s are shown, with dendritic Li shooting out (Scale bar: 1

μm). f-i, Time evolution of Li deposition into rGO host. Snapshots at 0 s, 100 s, 200 s and

300 s are shown, where no dendritic Li deposition can be observed (Scale bar: 200 nm).





Supplementary Figure 15. │ Ex situ SEM characterization on thickness variation. Ex

situ SEM characterization on the thickness change before (a), after (b) Li stripping and

after one stripping/plating cycle (c). After Li stripping, only minimal thickness decrease of

~20% can be observed. And after plating Li back, the thickness is similar to the original

state.





Supplementary Figure 16. │ Comparison on the voltage profiles at various current

density. Voltage profiles of Li-rGO (left column) and Li foil (right column) symmetric

cells at different cycles varied from the 1st to the 100th cycle. Profiles at different current

densities of 1 mA cm-2 (a,b), 2 mA cm-2 (c,d) and 3 mA cm-2 (e,f) were chosen for

comparison.





Supplementary Figure 17.│Long-cycle stabililty of layered Li-rGO electrode. a,

Galvanostatic cycling of symmetric Li-rGO electrode (blue) and bare Li foil (red) in the

first 500 hours, which is equivalent to 250 cycles. The current density was fixed at 1 mA

cm-2 with stripping/plating capacity of 1 mAh cm-2. b, The detailed voltage profiles from

80th to 100th cycle as marked with dash line in a. c, The detailed voltage profiles from 230th

cycle to 250th cycle as marked with dash line in a.





Supplementary Figure 18. │ Electrochemical cycling performance with ether-based

electrolyte. a, Galvanostatic cycling of Li foil (red) and Li-rGO film (blue) symmetric

cells in ether-based electrolyte (1M LiTFSI in 1:1, v/v DOL/DME with 1% LiNO3). Li-

rGO electrode showed much lower overpotential as well as more stable cycling stability

compared to the Li foil counterpart. The curves of 800,000-1,000,000 seconds (green dash

rectangle) and 2,800,000-3,000,000 seconds (blue dash rectangle) were enlarged and

shown in b and c, respectively. The Li-rGO electrode exhibited extremely stable cycling

performance in the DOL/DME electrolyte, with stable cycling of >450 cycles as shown in

a.





Supplementary Figure 19. │ Electrochemical cycling of symmetric cells at 2 mA cm-

2. Galvanostatic cycling of Li foil (red) and Li-rGO film (blue) in symmetric cell

configuration at the current density of 2 mA cm-2. The stripping/plating capacity was fixed

at 1 mAh cm-2. The detailed voltage profiles of the 1st, 10th, 50th, and 100th cycles were

further shown in the inset figures with scale of y axis shown on the left.





Supplementary Figure 20. │High areal capacity cycling stability of layered Li-rGO

electrodes. Galvanostatic cycling of symmetric Li-rGO electrode (blue) and bare Li foil

(red) with higher areal capacity of 3 mAh cm-2 in the first 300 hours, which is equivalent

to 50 cycles. The current density was fixed at 1 mA cm-2.





Supplementary Figure 21.│Electrochemical impedance spectroscopy

characterizations before cycling. Nyquist plots of the symmetric cells of Li foil (black)

and layered Li-rGO (red) before electrochemical cycling. Li foil showed considerably

larger interfacial resistance compared to the layered Li-rGO counterpart.





Supplementary Figure 22. │ Electrochemical performance of the LCO/Li-rGO cells.

Voltage profile comparison of the LCO/Li-rGO cells and the LCO/Li foil cells at the rate

of 0.2 C (a) and 10 C (c). b, Voltage profiles of the LCO/Li-rGO cells operated at various

rates from 0.2 C to 10 C. d, Cycling performance of the LCO/Li-rGO cells and the

LCO/Li foil cells at the rate of 1 C. Activation process was performed at the initial cycles

with the rate of 0.2 C.





Supplementary Figure 23. │ Electrochemical performance of the LTO/Li-rGO cells.

a, Rate capability of the LTO/Li-rGO and LTO/Li foil cells at various rates from 0.2 C to

10 C. Voltage profile comparison of the LCO/Li-rGO cells and the LCO/Li foil cells at

the rate of 0.2 C (b), 0.5 C (c), 1 C (d), 2 C (e), 4 C (f), and 10 C (g) were shown.





Supplementary Figure 24. Battery cycling with limited Li amount. │ Cycling stability

test with limited amount of Li. High areal capacity of LTO (~ 3 mAh cm-2) was used here.

LTO was used as the positive electrode and performed as the reservoir for Li. Since LTO

itself does not supply Li to the cell and it has high enough Coulombic efficiency, the Li

source is all from the Li metal electrode while Li loss during cycling should majorly

attributed to the loss on Li metal electrode.



Date post:	15-Apr-2018
Category:	Documents
Upload:	vankhanh
View:	219 times
Download:	4 times

Supplementary Information Layered reduced graphene … · Supplementary Information Layered reduced...

Documents