JOUL, Volume 3
Supplemental Information
Efficient 3D Printed Pseudocapacitive Electrodes with Ultrahigh MnO2 Loading Bin Yao, Swetha Chandrasekaran, Jing Zhang, Wang Xiao, Fang Qian, Cheng Zhu, Eric B. Duoss, Christopher M. Spadaccini, Marcus A. Worsley, and Yat Li
Supplementary Information
Efficient 3D Printed Pseudocapacitive Electrodes with Ultrahigh MnO2 Loading Bin Yao1,4, Swetha Chandrasekaran2,4, Jing Zhang1, Wang Xiao1, Fang Qian2, Cheng Zhu2, Eric B. Duoss2, Christopher M. Spadaccini2, Marcus A. Worsley2*, Yat Li1,3*
1
Department of Chemistry and Biochemistry, University of California, Santa Cruz, California
95064, United States. 2Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States. 3Lead Contact. 4These authors contributed equally.
*
Correspondence:
[email protected] (M. W.);
[email protected] (Y. L.)
S1
Figure S1. (A) Nitrogen adsorption-desorption isotherms and (B) pore size distribution of 3D printed graphene aerogel and a 3D G/MnO2 with MnO2 mass loading of 45.2 mg cm-2.
Figure S2. SEM image collected from a cross section of a 3D G/MnO2 electrode. Magnified SEM images collected from the regions highlighted by dashed boxes (A, B and C) are provided in Figure S3. S2
Figure S3. SEM images collected from the interior of graphene aerogel lattice. (A-C) Magnified SEM images collected from the dashed boxes highlighted in Figure S2. (D-F) Magnified SEM images collected from the dashed boxes highlighted in A, B and C. (G-I) Magnified SEM images collected from the dashed boxes highlighted in D, E and F.
S3
Figure S4 SEM image collected from a cross section of a bulk G/MnO 2 electrode. Magnified SEM images collected from the regions highlighted by dashed boxes (A, B and C) are provided in Figure S5.
S4
Figure S5. SEM images collected from the interior of bulk graphene aerogel. (A-C) Magnified SEM images collected from the dashed boxes highlighted in Figure S4. (D-F) Magnified SEM images collected from the dashed boxes highlighted in A, B and C. (G-I) Magnified SEM images collected from the dashed boxes highlighted in D, E and F.
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Figure S6. SEM image of MnO2 nanosheets deposited on a 3D printed graphene aerogel.
Figure S7. XRD spectra collected for the 3D printed graphene aerogel before and after electrodeposition of MnO2. The new peaks appear after electrodeposition correspond to the εMnO2 phase (JCPDS 30-0820).
S6
Figure S8. XPS spectra of 3D G/MnO2. A, Mn 2p and B, Mn 3s XPS spectra. The characteristic spin-energy separation of 11.9 eV between Mn 2P1/2 (654.3 eV) and Mn 2P3/2 (642.4 eV) peaks is observed, which is consistent with the previous reported MnO2 materials.1, 2 The linear relationship of the separation of peak energies (ΔE) in Mn3s core level spectrum can be used to determine the valance state of Mn.3 ΔE values of 4.7 and 5.4 eV correspond to Mn4+ and Mn3+, respectively. The ΔE value (5.13 eV) in this study shows the mean oxidation state of Mn in MnOx is around 3.37. The deviation from 4 in these MnOx nanosheets comes from the defects during the electrodeposition process.4 According to the previous research, the oxygen vacancy in MnO2 could improve the conductivity and enhance capacitive performance of MnO2.5
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Figure S9. (A) TEM image of MnO2 nanosheets deposited on a 3D printed graphene nanosheets. (B) Magnified TEM images collected from the dashed box highlighted in A. Insert shows the SAED pattern of graphene/MnO2 composite.
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Figure S10. EDS mapping of MnO2 nanosheets deposited on a 3D printed graphene nanosheets.
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Figure S11. Electrochemical performance of 3D printed graphene aerogel electrode. (A) Cyclic voltammograms collected at different scan rates. (B) Galvanostatic charging and discharging curves collected at different current densities.
Figure S12. Capacitance of 3D printed graphene aerogel electrode. (A) Areal capacitance and (B) gravimetric capacitance of 3D printed graphene electrodes collected at different current densities.
S10
Figure S13. (A) Areal and (B) volumetric capacitance collected for 3D G/MnO2 electrodes with different MnO2 mass loadings at different current densities.
Figure S14. Capacitance retention of 3D G/MnO2 electrodes with different MnO2 mass loadings obtained at different current densities. S11
Figure S15. Gravimetric capacitance of 3D G/MnO2 electrodes collected at different current densities. The gravimetric capacitances are normalized to the mass of the entire electrode (the total weight of graphene aerogel and MnO2).
S12
Figure S16. (A, C) CV curves of 3D printed graphene aerogel and non-3D printed graphene aerogel, (B, D) Their according current density under 0.35 V (vs. SCE) at different scan rates. Under potential 0.3 to 0.4 V (vs. SCE), both non-3D printed graphene aerogel and 3D printed graphene aerogel electrodes showed electrical double layer capacitance (EDLC). Their current increase linearly with the increase of scan rate at the same potential. By linearly fitting the current density with scan rate, the slope is their EDLC (Cdl), which shows similar results.6 Their EDLC are 9.37 mF and 9.091 mF for 1 cm2 3D and non-D printed graphene aerogels, respectively. Since they are the same materials, their normalized double layer capacitance per S13
area (Cnormalized) is the same. For carbonaceous materials, the normalized double layer capacitance is in between 15-50 μF/cm2. Here, an average value of 25 μF/cm2 is used for calculation.7 Thus, according to Equation S1, their surface area is similar (374.8 cm2 and 363.64 cm2 for 1 cm2-size 3D and non-D printed graphene aerogels, respectively.). ECSA = 𝐶
𝐶𝑑𝑙
𝑛𝑜𝑟𝑚𝑎𝑙𝑖𝑧𝑒𝑑
(Equation S1)
Where, ECSA is the electrochemical surface area of the electrodes. Cdl is the electrical double layer capacitance. Cnormalized is the normalized capacitance per area.
Figure S17. (A-C) SEM images of non-3D printed graphene aerogel, (D-F) SEM images of non3D printed graphene aerogel deposited with MnO2 nanosheets.
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Figure S18. Nyquist plots of 3D printed G/MnO2 and non-3D printed G/MnO2 electrodes with the same thickness.
Figure S19. Digital image of MnO2 nanosheets deposited on different carbon substrates.
S15
Figure S20. (A) SEM image of a bare carbon cloth. (B-D) SEM images of carbon cloth deposited with MnO2 nanosheets.
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Figure S21. (A) SEM image of a piece of bare carbon paper. (B-D) SEM images of carbon paper deposited with MnO2 nanosheets.
Figure S22. (A) SEM image of a piece of bare carbon fiber sheet. (B-D) SEM images of carbon fiber sheet deposited with MnO2 nanosheets.
S17
Figure S23. (A) SEM image of a bare carbon foil. (B-D) SEM images of carbon foil deposited with MnO2 nanosheets.
S18
Figure S24. Comparison of the areal capacitance of 3D G/MnO2, carbon cloth/MnO2, carbon paper/MnO2, carbon fiber/MnO2, and carbon foil/MnO2, at current densities of (A) 0.5 mA cm-2 and (B) 10 mA cm-2.
Figure S25. Nyquist plots of 3D printed G/MnO2 electrodes with different thickness
S19
Figure S26. Cycling stability of 3D printed G/MnO2 electrodes with different thickness at scan rate of 20 mV/s. The cycling stability of the 3D G/MnO2 electrodes with different thicknesses have been investigated under 20 mV/s. All the four electrodes exhibit excellent cycling stability over 10000 cycles (98.1 % for 1 mm electrode; 98.8 % for 2 mm electrode; 101.5 % for 3 mm electrode; and 100.0 % for 4 mm electrode).
Figure S27. SEM images of the 3D G/MnO2 electrodes after stability test.
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Figure S28. Ragone plots compare the energy densities and power densities of the 8 mm-thick and 2 mm-thick 3D G/MnO2 symmetric supercapacitor devices with the benchmark values previously reported for representative supercapacitors (Au/MnO2 SSC,8 G/MnO2//G ASC,9 MoO3-x//PANI ASC,10 MnO2/H-TiO2-x//C/H-TiO2-x ASC,11 3D printed GA SSC,12 3D GA SSC,13 PPy SSC,14 d-Ti3C2 SSC,15 MnO2/CNPs SSC,16 CDC/TiC MSC,17 Graphite/PANI SSC,18 TiN SSC,19 LSG-EC SSC20).
A new asymmetric device by employing the 3D G/MnO2 with a relatively small mass loading (10.3 mg/cm2, still at a practically feasible mass loading level) as positive electrode and 3D S21
printed graphene aerogel deposited with mixed-valence vanadium oxide (3D G/VOx, 3.6 mg/cm2) as negative electrode has been successfully fabricated. This asymmetric device achieves a working voltage window of 2.2 V, which is more than twice of the voltage of the symmetric devices based on two identical 3D G/MnO2 electrodes (Figure S29). When two devices are connected in series, they can be charged to 4.4 V at a rate of 50 mA/cm2 within 36 s. This tandem device with a working area of only 0.2 cm2 can power a blue LED (3.0V, 5 mm) for 5 min (Figure S30). It shows that the devices can be used for applications that requires higher voltage output.
Figure S29. CV and GCD curves of asymmetric supercapacitors based on 3D printed G/MnO2 and 3D printed G/VOx.
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Figure S30. Schematic diagram and photo of the lighted blue LED powered by two asymmetric 3D printed supercapacitors in series.
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Table S1. Summary of areal capacitive performance of electrodes with high mass loading of MnO2.
Materials
Mass loading (mg cm-2)
Areal Capacitance
Rate capability
Ref.
MWCNT/MnO2
1
0.26 F cm-2 @ 2 mV s-1
43.9% (2-100 mV s-1)
21
PEDOT/MnO2
1.3
0.17 F cm-2 @ 0.76 mA cm-2
47% (0.76-5 mA cm-2)
22
N-doped graphene/MnO2
2
0.43 F cm-2 @ 0.25 A g-1
69.2% (0.25-2A g-1)
23
Self-branched MnO2
3.4
0.6 F cm-2 @ 5 mV s-1
55% (2-20 mV s-1)
24
ZnO/MnO2
5.4
2.28 F cm-2 @ 0.5 A/g
35.4% (0.5-10 A g-1)
25
MnO2/Graphene/Ni foam
6.1
1.5 F cm-2 @ 10 mV s-1
30% (10-100 mV s-1)
26
CNT/MnO2
8.3
2.8 F cm-2 @ 0.05 mV s-1
55.3% (0.05-0.8 mV s-1)
2
3D graphene/CNT/MnO2
8.4
~0.73 F cm-2 @ 5 mV s-1
12% (5-100 mV s-1)
27
MnO2/PEDOT:PPS
8.6
~0.8 F cm-2 @ 4 mV s-1
8% (4-100 mV s-1)
28
3D graphene/MnO2
9.8
~1.47 Fcm-2 @ 2 mV s-1
7% (2-100 mV s-1)
29
Ni nanowire array/MnO2
16.8
1.85 F cm-2 @ 1 mV s-1
--
30
MnO2/Ni foam
18
2.8 F cm-2 @ 2 mA cm-2
31% (2-20 mA cm-2)
31
MnOx-h
23.5
4.2 F cm-2 @ 5 mV s-1
30% (5-100 mV s-1)
4
11.55 F cm-2 @ 0.5 mA cm-2
73.2 % (0.5-10 mA cm-2)
9.82 F cm-2 @ 2 mA cm-2
67.7% (0.5-20 mA cm-2)
(1 mm)
8.46 F cm-2 @ 10 mA cm-2
55.6% (0.5-50 mA cm-2)
3D printed Graphene/MnO2
44.13 F cm-2 @ 0.5 mA cm-2
70.9 % (0.5-10 mA cm-2)
40.52 F cm-2 @ 2 mA cm-2
64.6% (0.5-20 mA cm-2)
31.31 F cm-2 @ 10 mA cm-2
54.7% (0.5-50 mA cm-2)
3D printed Graphene/MnO2
(4 mm)
45.2
182.2
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Table S2. Equivalent series resistances (Rs), charge-transfer resistances (Rct) and Warburg resistances (W) of the equivalent circuit fitted with the Nyquist plots for 3D printed G/MnO2 electrode and non-3D printed G/MnO2 electrode.
Electrode
Rs (Ω·cm2)
Rct (Ω·cm2)
W (Ω·cm2·s0.5)
3D printed G/MnO2
1.19
0.0254
0.1073
Non-3D printed G/MnO2
1.18
0.1196
0.1662
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Table S3. Summary of the areal capacitance, gravimetric capacitance and volumetric capacitance of electrodes with high mass loading of MnO2. (All values are normalized to the weight/volume of the entire electrode)
Materials
Areal Capacitance (F cm-2)
Gravimetric Capacitance (F g-1)
Volumetric Capacitance (F cm-3)
Mass Loading (mg cm-2)
Mass Ratio (MnO2/ Electrode)
Ref.
ECC/MnO2
4.2
118.3
52.5
23.5
66.2%
4
Ni Foam/MnO2
2.8
49.8
55.8
18
32.1%
31
Wood carbon/MnO2
4.2
55.4
41.6
25
33.3%
32
G/MnO2
1.4
130
71
9.8
89.7%
29
G/Ni/MnO2
3.2
79.6
31.8
13.6
34%
26
CNT/MnO2
1.3
70.8
16.3
3.1
16.9%
33
TCC/MnO2
1.2
63.4
35.7
13
69.3%
34
MnO2/porous carbon cloth
2.1
178
26.1
4.5
38.4%
35
11.55
231.9
115.5
45.2
90.76 %
this work
44.13
220.4
110.3
182.2
90.83 %
this work
3D printed Graphene/MnO2 (1 mm) 3D printed Graphene/MnO2 (4 mm)
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Table S4. Equivalent series resistances (Rs), charge-transfer resistances (Rct) and Warburg resistances (W) of the equivalent circuit fitted with the Nyquist plots for the 3D printed G/MnO2 electrodes with different thickness.
Electrode Thickness (mm)
Rs (Ω·cm2)
Rct (Ω·cm2)
W (Ω·cm2·s0.5)
1
1.19
0.0254
0.1073
2
1.23
0.0385
0.1156
3
1.24
0.1050
0.1186
4
1.28
0.1234
0.1329
S27
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