Supplementary Figures

Transcription

1 Supplementary Figures a Supplementary Figure 1 Structure of the TiO 2 NAs/CT cathode. (a) Transmission electron microscopy (TEM) image of the TiO 2 NAs. Scale ars, 100 nm. () HRTEM image of (a). Scale ars, 2 nm.

2 Supplementary Figure 2 SEM mapping images. SEM image of TiO 2 NAs/CT and the corresponding elemental mapping images of C, O and Ti and all three elements in the composite. Scale ars, 10 μm. The C element is distriuted with diameter of 12 μm. The O and Ti elements are uniformly distriuted around a single CT. The diameter of the resulting composite TiO 2 NAs/CT had increased to aout 13 μm from 12 μm in the pristine-ct. All these demonstrate the core-shell configuration of TiO 2 NAs/CT and this structure could effectively prevent the pristine- CT from decomposing. S2

3 a c d Supplementary Figure 3 Optical photographs. Optical photographs of (a, ) CT and (c, d) TiO 2 NAs/CT cathodes. S3

4 Voltage (V) Pristine-CT TiO 2 NAs/CT Current density: 100 mah g Capacity (mah g -1 ) Supplementary Figure 4 Discharge curves of the Ar-filled cells. The current density, 100 ma g -1. The ackground discharge capacity is negligile within the voltage range, which suggests that the discharge capacities of Li-O 2 cells are derived from the oxygen reduction. S4

5 Voltage (V) Voltage (V) a st 5th 10th 11th 12th 13th Capacity (mahg -1 ) st 50th 100th 150th 200th 250th 300th 350th 400th 450th 500th Capacity (mah g -1 ) Supplementary Figure 5 Cycling performance. Discharge-charge curves of the Li-O 2 cells with the (a) pristine-ct and () TiO 2 NAs/CT cathodes at different cycles. Current density: 100 ma g -1. S5

6 Voltage (V) Cut-off voltage (V) Capacity (mah g -1 ) a st 10th 20th 50th 80th 100th 112th Capacity (mahg -1 ) Cycle numer Supplementary Figure 6 Cycling performance. Discharge-charge curves of flexile Li-O 2 cells with TiO 2 NAs/CT cathode (a) and corresponding cycling performance () with a fix capacity of 1000 mah g -1 at a current density of 100 ma g -1. S6

7 Voltage (V) Voltage (V) Voltage (V) Voltage (V) Voltage (V) Voltage (V) a c st 5th 10th 20th 30th 40th 50th 60th 70th 80th 90th 100th capacity (mah g -1 ) st 5th 10th 20th 30th 40th 50th 60th 70th 80th 90th 100th capacity (mah g -1 ) d e f st 5th 10th 20th 30th 40th 50th 60th 70th 80th 90th 100th capacity (mah g -1 ) st 5th 10th 20th 30th 40th 50th 60th 70th 80th 90th 100th capacity (mah g -1 ) st 5th 10th 20th 30th 40th 50th 60th 70th 80th 90th 100th capacity (mah g -1 ) 1st 5th 10th 20th 30th 40th 50th 60th 70th 80th 90th 100th capacity (mah g -1 ) Supplementary Figure 7 Cycling performance. (a-c) Discharge-charge curves of the Li-O 2 cells with the devices ended to 0, 180 and 360, respectively. (d-f) Discharge-charge curves of the Li-O 2 cells with the devices twisted to 0, 180 and 360, respectively. S7

8 a Supplementary Figure 8 Optical photograph and SEM image. (a) Optical photograph and () SEM image of the TiO 2 NAs/CT cathode after twisting 1000 cycles. S8

9 a c d Supplementary Figure 9 SEM characterization. (a) SEM images of the recharged pristine- CT, Scale ars, 10 μm. () The enlarged image of (a). Scale ars, 200 nm. (c) Image of the recharged TiO 2 NAs/CT cathode. Scale ars, 10 μm. (d) The enlarged image of (c). Scale ars, 200 nm. The current density is 100 ma g -1 and the specific capacity is 500 mah g -1. S9

10 mv s mv s a k 0.1 ml 0.2 ml 0.3 ml 0.4 ml 0.5 ml 0.6 ml 0.7 ml 0.8 ml 0.9 ml 1.0 ml k 6k 5k 4k 3k 2k Linear fit y= x 1k Time (min) O 2 (ml) Supplementary Figure 10 GC signal and caliration curve of O 2. (a) GC signal curves otained y injecting O 2 into column with different volume otained from a thermal conductivity detector (TCD). () GC caliration curve otained according to (a). S10

11 mv s mv s a 0.1 ml 0.2 ml 0.3 ml 0.4 ml 0.5 ml 0.6 ml 0.7 ml 0.8 ml 0.9 ml 1.0 ml k 3k 2k Linear fit 200 1k y= x Time (min) CO 2 (ml) Supplementary Figure 11 GC signal and caliration curve of CO 2. (a) GC signal curves otained y injecting CO 2 into column with different volume otained from a thermal conductivity detector (TCD). () GC caliration curve otained according to (a). S11

12 Supplementary Figure 12 In-situ DEMS test. Gas evolution from the cell with TiO 2 NAs/CT cathode, room temperature, with current density of 100 ma g -1. S12

13 a c d e f Supplementary Figure 13 SEM characterization. (a) SEM image of the TiO 2 NAs/CT cathode after 10 th cycle. Scale ars, 10 μm. () The enlarged image of (a). Scale ars, 500 nm. (c) SEM image of the TiO 2 NAs/CT cathode after 50 th cycle. Scale ars, 10 μm. (d) The enlarged image of (c). Scale ars, 500 nm. (e) SEM image of the TiO 2 NAs/CT cathode after 100 th cycle. Scale ars, 10 μm. (f) The enlarged image of (e). Scale ars, 500 nm. S13

14 -Z''Ohms -Z''Ohms a R ohm R int1 R int2 W R ohm R int1 R int2 W CPE1 CPE2 300 CPE1 CPE Exp: Pristine Exp: Discharge Exp: Charge Fit: Pristine Fit: Discharge Fit: Charge Z'/Ohms Exp: Pristine Exp: Discharge Exp: Charge Fit: Pristine Fit: Discharge Fit: Charge Z'/Ohms Supplementary Figure 14 Impedance spectra. (a) Electrochemical impedance spectra changes (pristine, first discharge and recharged) of the Li-O 2 cell with pristine-ct cathode. () Electrochemical impedance spectra changes of the cell with the TiO 2 NAs/CT cathode. The solid line was the fitting line ased on the equivalent circuit. S14

15 a c d Supplementary Figure 15 SEM characterization. (a) SEM image of the TiO 2 NAs/CT cathode after 356 th discharge. Scale ars, 10 μm. () The enlarged image of (a). Scale ars, 500 nm. (c) SEM image of the TiO 2 NAs/CT cathode after 356 th recharged. Scale ars, 10 μm. (d) The enlarged image of (c). Scale ars, 500 nm. The current density is 100 ma g -1 and the specific capacity is 500 mah g -1. S15

16 Voltage (V) Capacity (mah g -1 ) Voltage (V) Capacity (mah g -1 ) a theta (degree) theta (degree) c d Cycle numer Cycle numer Supplementary Figure 16 Recoverale performance. (a) SEM images of the third recovered TiO 2 NAs/CT cathode. Scale ars, 5 μm. () SEM images of the fifth recovered TiO 2 NAs/CT cathode. Scale ars, 5 μm. Inset in (a, ) is the corresponding XRD patterns. (c) The corresponding variation of voltage on the terminal of discharge of the third recovered TiO 2 NAs/CT cathode with current density of 100 ma g -1. (d) The corresponding variation of voltage on the terminal of discharge of the fifth recovered TiO 2 NAs/CT cathode. S16

17 Intensity (a.u.) a Rutile TiO Pd * * * Rutile TiO 2 Pd * theta (degree) Supplementary Figure 17 SEM image and XRD patterns. (a) SEM image of the Pd modified TiO 2 NAs/CT cathode. Scale ars, 10 μm. () XRD patterns of the TiO 2 NAs/CT cathode and the Pd modified TiO 2 NAs/CT cathode. S17

18 Supplementary Figure 18 TEM mapping images. TEM image of of the Pd modified TiO 2 NAs/CT cathode and the corresponding elemental mapping images of Ti, O and Pd. The Ti, O and Pd elements are uniformly distriuted around a single TiO 2 NAs. S18

19 Volatage (V) Pristine-CT TiO 2 NAs/CT TiO 2 NAs/CT/Pd Current density: 100 mah g Capacity (mah g -1 ) Supplementary Figure 19 Cell electrochemical performance. First discharge-charge curves of Li-O 2 cells with pristine-ct cathode, TiO 2 NAs/CT, and Pd modified TiO 2 NAs/CT cathodes. The discharge and charge voltage of the Li-O 2 cell can e significantly improved with the help of the Pd modified TiO 2 NAs/CT cathode, which enhances the round-trip efficiency. S19

20 Supplementary Tale 1 The amount of the released gas. These results are otained on the asis of the GC signal spectra and caliration curves (Figs. S10 and S11). Both of two cells with pristine-ct and TiO 2 NAs/CT cathodes were discharged and recharged with the current density of 100 ma g -1. Pristine-CT TiO 2 NAs/CT mv s (O2) mv s (CO2) V (O2) (μl) V (CO2) (μl) S20

21 Supplementary References 41. Y. M. Cui, Z. Y. Wen, Y. Liu, A free-standing-type design for cathodes of rechargeale Li- O 2 atteries. Energy Environ. Sci. 4, (2011). S21