Highly Dispersed Metal and Oxide Nanoparticles on Ultra-Polar

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Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A. This journal is © The Royal Society of Chemistry 2017

Supplementary Materials

Carbon as Efficient Cathode Materials for Li-O2 Batteries

Xueyi Lu,a Guang-Ping Hao,b,* Xiaolei Sun,a Stefan Kaskel,b Oliver G. Schmidta

a Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstraße 20, Dresden 01069, Germany

b Department of Inorganic Chemistry, Technische Universität Dresden, Bergstraße 66, Dresden 01069,

Germany

*Corresponding authors: Email: [email protected]

Fig. S1 Top-view SEM image of ultra-polar carbon (UPC). The carbon displays a hierarchically porous morphology.

Fig. S2 N2 adsorption-desorption isotherms and pore size distributions (inset) of UPC and SP.

Fig. S3 SEM images of SP and SP supported Pd nanoparticles. Different from Pd/UPC, the Pd nanoparticles on the surface of SP are easy to aggregate during the preparation process.

Fig. S4 Cyclic voltammetry of Li-O2 battery with SP and UPC electrodes at a scan rate of 0.1 mV s1. The UPC electrode shows higher onset oxygen reduction potential than SP, which is in line with the discharge/charge test results (Fig. 5).

5 5 (a) SP @100mA g -1 (b) UPC @100mA g -1

V V

/ /

e e

g g a

a 3

t t

l l

o o V V 2 1st 2nd 3rd 4th 1st 2nd 3rd 4th 2 1 5th 6th 7th 8th 5th 6th 7th 8th 9th 10th 9th 10th

0 1 0 600 1200 1800 2400 3000 3600 0 600 1200 1800 2400 3000 3600 Time / s Time / s

5 5 (c) (d)

-1

4 Pd/UPC @100mA g

e 4 g

a SP

t V

3 l

/ o

UPC

e l

g charge

a Pd/UPC

t n

m r

V 2 e

1st 2nd 3rd 4th T 3 E=2.96 V 5th 6th 7th 8th 1 9th 10th discharge 0 2 0 600 1200 1800 2400 3000 3600 0 1 2 3 4 5 6 7 8 9 10 Time / s Cycle number

Fig. S5 Discharge-charge profiles of Li-O2 batteries with SP, UPC and Pd/UPC electrodes at a current density of 100 mA g1.

5 5

(a) (b) -1 UPC @200mA g 4 4 -1

SP @200mA g V

V 3

l g

o 3

l o

V 2 1st 2nd 3rd 4th 1st 2nd 3rd 4th 2 1 5th 6th 7th 8th 5th 6th 7th 8th 9th 10th 9th 10th

0 1 0 600 1200 1800 2400 3000 3600 0 600 1200 1800 2400 3000 3600 Time / s Time / s

5 5 (c) (d)

4 Pd/UPC @200mA g -1

e 4 g

a SP

t V

3 l

/ o

UPC

e l

g charge Pd/UPC

t n

m r

V 2 e

1st 2nd 3rd 4th T 3 E=2.96 V 5th 6th 7th 8th 1 9th 10th discharge 0 2 0 600 1200 1800 2400 3000 3600 0 1 2 3 4 5 6 7 8 9 10 Time / s Cycle number

Fig. S6 Discharge-charge profiles of Li-O2 batteries with SP, UPC and Pd/UPC electrodes at a current density of 200 mA g1.

5 5 (a) (b) UPC @300mA g -1

4 4

SP @300mA g -1 V

V 3

/ /

e e g

g 3

a a

t t

l l

o o V V 2 1st 2nd 3rd 4th 1st 2nd 3rd 4th 2 1 5th 6th 7th 8th 5th 6th 7th 8th 9th 10th 9th 10th

0 1 0 600 1200 1800 2400 3000 3600 0 600 1200 1800 2400 3000 3600 Time / s Time / s

5 5 (c) (d) Pd/UPC @300mA g -1

e 4 SP g

a UPC

V t

3 l

o Pd/UPC

o m

2 r V

e charge 1st 2nd 3rd 4th T 3 E=2.96 V 5th 6th 7th 8th discharge 1 9th 10th

0 2 0 600 1200 1800 2400 3000 3600 0 1 2 3 4 5 6 7 8 9 10 Time / s Cycle number

Fig. S7 Discharge-charge profiles of Li-O2 batteries with SP, UPC and Pd/UPC electrodes at a current density of 300 mA g1.

5 5 (a) (b)

4 4

SP @300 mA g-1 UPC @300 mA g-1

3 3 Voltage/ V Voltage/ V 2 2

1st 5th 10th 20th 1st 5th 10th 30th 1 1 30th 40th 50th 52nd 50th 70th 100th 104th

0 0 0 200 400 600 800 1000 0 200 400 600 800 1000 Specific capacity / mAh g-1 Specific capacity / mAh g-1

1 Fig. S8 Discharge-charge profiles of Li-O2 batteries with SP and UPC electrodes at 300 mA g under a specific capacity of 1000 mAh g1.

Fig. S9 Discharge-charge profiles of Li-O2 batteries with SP, UPC and Pd/UPC electrodes at 100 mA g1.

Fig. S10 SEM images of Pd/UPC electrode after the 1st charge (a, b) and 5th discharge (c, d) processes.

Fig. S11 (a) SEM image of pure carbon paper current collector. (b-f) SEM images of UPC supported RuO2 fixed on the carbon paper and the corresponding EDS elemental mapping.

Fig. S12 (a, b) TEM and HR-TEM images of RuO2/UPC. (c) Raman spectrum of RuO2/UPC. The lattice space is calculated to be 0.25 nm, corresponding to RuO2 (101).[1]

(a) F 1s (b) C 1s + Ru 3d C 1s

O 1s

F auger Intensity Intensity / a.u. Intensity Intensity / a.u. Ru 3p N 1s

1200 1000 800 600 400 200 0 290 288 286 284 282 280 278 Binding energy / eV Binding energy / eV

Intensity Intensity / a.u. Intensity / a.u.

510 500 490 480 470 460 538 536 534 532 530 528 526 Binding energy / eV Binding energy / eV

Fig. S13 Wide-scan survey and detailed XPS spectra of RuO2/UPC. It is difficult to distinguish the C 1s from Ru 3d because they overlap in the region. The binding energy of Ru 3p3/2 is ~463.9 eV, indicating that the Ru exists in the form of RuO2 in the composite.[2, 3]

100 4.5 (a) (b) RuO2/UPC RuO2/UPC 80 4.0

3.5 60

3.0 40 VoltageV /

2.5 Round-tripefficiency % / 20 70 mA g-1 200 mA g-1 500 mA g-1 2.0 0 0 200 400 600 800 1000 70 200 500 -1 Specific capacity / mAh g Current densities / mA g-1

Fig. S14 Discharge-charge curves of Li-O2 batteries with RuO2/UPC electrode at current densities of 70, 200 and 500 mA g1 and the corresponding round-trip efficiencies.

5 5

(a) SP (b) RuO2/UPC

4 4

V V

/ /

e e g

g 3 3

a a

t t

l l

o o

V V

2 1st (50 mA g-1 ) 6th (100 mA g-1) 11th (200 mA g-1 ) 2 1st (50 mA g-1) 6th (100 mA g-1 ) 11th (200 mA g-1)

16th (300 mA g-1) 21st (400 mA g-1) 26th (500 mA g-1) 16th (300 mA g-1) 21st (400 mA g-1) 26th (500 mA g-1)

1 1 0 600 1200 1800 2400 3000 3600 0 600 1200 1800 2400 3000 3600 Test time / s Test time / s

5 5 (c) (d) SP RuO2/UPC

4 4

V V

/ /

e e

g g a

a 3 3

t t

l l

o o

V V

31st 32nd 33rd 34th 31st 32nd 33rd 34th 2 2 35th 36th 37th 38th 35th 36th 37th 38th 39th 40th 39th 40th

1 1 0 600 1200 1800 2400 3000 3600 0 600 1200 1800 2400 3000 3600 Test time / s Test time / s

Fig. S15 (a, b) Discharge-charge profiles of Li-O2 batteries with SP and RuO2/UPC electrodes being tested from 50 to 500 mA g1 for 5 cycles at each current density. (c, d) Discharge-charge

1 profiles of Li-O2 batteries with SP and RuO2/UPC electrodes being tested from 50 to 100 mA g for 5 cycles at each current density (From the 31st to the 40th cycle).

Fig. S16 Terminal voltages profiles of Li-O2 batteries with SP and RuO2/UPC electrodes tested sequentially at various current densities.

Fig. S17 SEM images of RuO2/SP fixed on the carbon paper and the corresponding EDS pattern.

RuO2/SP were prepared by the same method as RuO2/UPC. The spectra shows that the Ru disperse not well on the SP support.

References

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[2] X. Guo, P. Liu, J. Han, Y. Ito, A. Hirata, T. Fujita, M. Chen, Adv. Mater., 2015, 27, 6137-

6143.

[3] B. Folkesson, Acta Chem. Scand., 1973, 27, 287-302.