Supporting Information

Transcription

1 Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A. This journal is The Royal Society of Chemistry 2015 Supporting Information High-Performance Supercapacitors Based on MnO 2 Tube-in-Tube Arrays Xue-Feng Lu, An-Liang Wang, Han Xu, Xu-Jun He, Ye-Xiang Tong, and Gao-Ren Li* MOE Laboratory of Bioinorganic and Synthetic Chemistry, KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou , China Material characterization The morphology and microstructure of the fabricated materials are characterized by field-emission scanning electronmicroscopy (FE-SEM, JSM-6330F), X-raydiffractometry (XRD, D8ADVANCE), transmission electron microscopy (TEM, Tecnai G2 F30). The chemical composition of the samples was characterized by energy-dispersive X-ray spectroscopy (EDS, INCA 300) and X-ray photoelectron spectroscopy (XPS, ESCALAB 250). All XPS spectra were corrected using the C 1s line at ev. Inductively coupled plasmaatomic emission spectroscopy (ICP, SPECTRO) was used to analyze the loading of manganese dioxide. The mass loading of MnO 2 TTAs and STAs is 0.32 and 0.16 mg/cm 2, respectively. Calculation methods of C sp, power density and energy density The specific capacitance (C sp ) determined from the cyclic voltammometric curves were calculated

2 according to Eqs. (1~2): x C sp = 1 idt A V y x C sp = 1 idt w V y (1) (2) Where i, V, A and w were the current (ma), voltage range of one scanning segment (V), electrode area (cm 2 ) and weight of the electrode material (mg), respectively. The specific capacitance (Csp) determined from the chronopotentiometric curves were calculated according to Eqs. (3~4): C sp = I t A V C sp = I t w V (3) (4) The energy density (E), and power density (P) were also calculated from the chronopotentiometric curves according to Eqs (5~6): E = 1 2 C sp( V) 2 (5) P = E t (6) Where I is the charge/discharge current, t is the time for a full charge ordischarge, w is the mass of the active electrode material, and V is the voltage change after a full charge/discharge.

3 (a) (b) (c) (d) (e) (f) Figure S1. (a-e) Optical images of carbon fiber cloth (CFC) at normal states and various bending states, indicating the excellent flexible ability of the CFC; (f) Typical SEM image of carbon fibers in the CFC.

4 (a) (b) (c) (d) Figure S2. SEM images of various precursors: (a) ZnO MRAs/CFC, (b) 2 MRAs/CFC, (c) and (d) 2 MnO 2 MRAs/CFC.

5 (a) (b) Figure S3. SEM images of the MnO 2 tube-in-tube arrays (TTAs) with different magnifications on Ti substrate.

6 Figure S4. SEM image of MnO 2 STAs/CFC. (a) (b) Figure S5. (a) TEM image, (b) HRTEM image and SAED (inset in (b)) of MnO 2 STAs.

7 O 1s Mn 2p Mn 2p 3 1 Mn 2s Mn LM1 Mn LM2 Counts/s Mn LM3 O 2s Counts/s O KL1 O KL C 1s Mn 3p Mn 3s Binding Energy/eV Figure S6. The XPS full spectrum of MnO 2 TTAs/CFC (Mn-O) O 2- O 2- (O-H) O 1s Binding Energy/eV Figure S7. XPS spectrum of O 1s of the MnO 2 TTAs/CFC.

8 Potential/V Specific capacitance(mf/cm 2 ) Current/A MnO2 TTAs/CFC MnO2 STAs/CFC CFC mv/s Potential/V Figure S8. CVs of MnO 2 TTAs/CFC, MnO 2 STAs/CFC, and CFC at 100 mv/s (a) A/g A/g A/g A/g A/g 6.25 A/g (b) MnO2 TTAs/CFC MnO2 STAs/CFC Time/sec Current density (A/g) Figure S9. (a) GCD curves of MnO 2 TTAs/CFC at different current densities among 6.25~37.5 A/g. (b) The dependence of C sp on current densities for MnO 2 TTAs/CFC among 6.25~37.5 A/g.

9 Potential/V Current/A Potential/V (a) (c) Potential/V 5 mv/s 10 mv/s 20 mv/s 50 mv/s 100 mv/s A/g A/g A/g A/g A/g 6.25 A/g (b) 3.75 A/g A/g 1.25 A/g A/g A/g A/g Time/sec Time/sec Figure S10. (a) CVs of MnO 2 STAs/CFC at different scan rates, (b-c) GCD curves of MnO 2 STAs/CFC at different current densities.

10 Figure S11. SEM image of MnO 2 STAs/CFC after 2000 cycles. Figure S12.SEM image of MnO 2 TTAs/CFC after 2000 cycles.

11 -Z"/ohm -Z"/ohm (a) Before 2000 cycles After 2000 cycles Z'/ohm Z'/ohm Figure S13. Nyquist plots of MnO 2 STAs/CFC before and after 2000 cycles.

12 (a) Advantages of CFC (b) Figure S14. The fast ion and electron transmissions and high utilization rate in MnO 2 TTAs/CFC. (a) Schematic illustration for fast ion and electron transmissions in MnO 2 TTAs/CFC electrode; (b) TTAs architecture provides highways for ions and high utilization for MnO 2 TTAs/CFC electrode.

13 Specific capacitance(mf/cm 2 ) 40 MnO 2 TTAs/CFC-SSC MnO 2 STAs/CFC-SSC Scan rate(mv/s) Figure S15. C sp of MnO 2 TTAs/CFC-SSC and STAs/CFC-SSC as a function of scan rate Capacitance retention/% Bend angle/degree Figure S16. C sp retention of MnO 2 TTAs/CFC-SSC device measured at different bend angles. Insets are the pictures of the device under different bend conditions and the schematic illustration of bend angle.

14 Energy density(wh/kg) Current/mA Potential/V (a) 5 mv/s 10 mv/s 20 mv/s 50 mv/s 100 mv/s (b) ma/g ma/g ma/g ma/g ma/g 62.5 ma/g Potential/V Time/sec Figure S17. (a) CVs of MnO 2 STAs/CFC-SSC at different scan rates and (b) GCD curves of MnO 2 STAs/CFC-SSC at different current densities MnO 2 TTAs/CFC-SSC MnO 2 STAs/CFC-SSC Power density(kw/kg) Figure S18. Ragone plots of MnO 2 TTAs/CFC-SC and MnO 2 STAs/CFC-SSC.