A Self-Healable and Cold-Resistant Supercapacitor Based on a Multifunctional. Hydrogel Electrolyte

Transcription

1 Supporting Information A Self-Healable and Cold-Resistant Supercapacitor Based on a Multifunctional Hydrogel Electrolyte Feng Tao, Liming Qin, Zhikui Wang, Qinmin Pan* (State Key Laboratory of Robotics and Systems, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 151, P. R. China) Corresponding author: Qinmin Pan Harbin Institute of Technology, Harbin 151, P. R. China panqm@hit.edu.cn S-1

2 ..5 SA-g-DA SA Absorbance Ar-H..5 nm ppm (c) 1.. Abs = 1.75C dopa Wavelength (nm) Absorbance C dopa (mg ml -1 ) Figure S1. 1 H-NMR spectra of SA-g-DA, UV-vis spectra of SA and SA-g-DA, and (c) absorbance vs. concentration curve for standard dopamine hydrochloride solutions. Figure S1a is the 1 H-NMR (D O) spectra of SA-g-DA. Besides the peaks of alginate at δ (ppm).7-.9, it also clearly shows the peaks of grafted catecholic moiety at δ (ppm).1-7. (Ar H),.5 (Ar CH ),. (CONH CH ). UV-Vis spectra of Figure S1b further confirm that dopamine is grafted to sodium alginate because an absorbance ascribed to catecholic moiety is observed at nm for SA-g-DA. The absorbance was then used to calculate the amount of the grafted dopamine. By comparing with the absorbance vs. concentration curve of standard dopamine solutions (Figure S1c), we found that.-5. mol% of dopamine was grafted to sodium alginate in this study. S-

3 5 5 5 (c) Ionic conductivity (ms cm -1 ) Ionic conductivity (ms cm -1 ) Ionic conductivity (ms cm -1 ) Grafting amount of dopamine (mol%) Borax content (wt%) 1 5 SA-g-DA content (wt%) Figure S. Effect of grafting amount of dopamine, borax content and (c) SA-g-DA content on the ionic conductivity of the SA-g-DA/KCl electrolytes. Figure Sa-b shows that both grafting amount of dopamine and borax content have little impact on the ionic conductivity of the hydrogel electrolytes. On the contrary, increasing the content of SA-g-DA deteriorates the conduction of the electrolytes (Figure Sc) (15 o C) (15 o C) (5 o C) (5 o C) ( o C) ( o C) Temperature ( o C) Figure S. Stress-strain curves and tensile strength and healing efficiency of the SA-g-DA/KCl electrolytes after healing at different temperatures for 1 min. The electrolytes contained 1 mol L 1 KCl, 5. mol% DA,.5 wt% SA-g-DA and 1.5 wt% borax and were stabilized at 15 o C, 5 o C and o C for 1 hour before cut/healing mol%. mol%.7 mol%.7 mol% 5. mol% 5. mol% Grafting amount of dopamine (mol%) S-

4 Figure S. Effect of grafting amount of dopamine on the stress-strain curves, tensile strength and healing efficiency of the SA-g-DA/KCl electrolytes. The electrolytes contained 1 mol L 1 KCl,.5 wt% SA-g-DA and 1.5 wt% borax wt%.5 wt%.5 wt%.5 wt%.5 wt%.5 wt% 1. wt% 1. wt% 1.5 wt% 1.5 wt% Borax content (wt%) Figure S5. Effect of borax content on the stress-strain curves, tensile strength and healing efficiency of the SA-g-DA/KCl electrolytes. The electrolytes contained 1 mol L 1 KCl, 5. mol% DA and.5 wt% SA-g-DA wt% 1.5 wt%.5 wt%.5 wt%.5 wt%.5 wt%.5 wt%.5 wt% 5.5 wt% 5.5 wt% SA-g-DA content (wt%) Figure S. Effect of the content of SA-g-DA on the stress-strain curves, tensile strength and healing efficiency of the SA-g-DA/KCl electrolytes. The electrolytes contained 1 mol L 1 KCl, 5. mol% DA and 1.5 wt% borax. S-

5 1 mol L -1 1 mol L -1 mol L -1 mol L -1 mol L -1 mol L KCl concentration (mol L -1 ) Figure S7. Effect of KCl content on the stress-strain curves, tensile strength and healing efficiency of the SA-g-DA/KCl electrolytes. The electrolytes contained.5 wt% SA-g-DA, 5. mol% DA and 1.5 wt% borax. Figure S-7 shows the effect of the content of grafted dopamine, borax, SA-g-DA and KCl on the tensile strength and mechanical healing efficiency of the resulting hydrogel electrolytes. Generally, increasing the content of grafted dopamine, borax and SA-g-DA leads to a higher mechanical strength, since more catechol-borate ester bonds can be formed in the electrolytes. On the contrary, increasing KCl content from 1. to. mol L 1 significantly decreases the tensile strength of the electrolytes (Figure S7). One reason for the decreased strength is that although alginate chains have good salt-tolerance, excessive KCl still damages the hydrogen bonding between alginate chains and water molecules. The damage causes alginate chains to dehydrate and aggregate in water. As a result, effective interpenetration of alginate chains becomes difficult and thus leads to a lower mechanical strength. On the other hand, the amount of borax, KCl and grafted dopamine had little effect on the mechanical healing efficiency of the electrolytes. The mechanical healing efficiency of the electrolytes decreases when the content of SA-g-DA is increased from 1.5 to 5.5 wt% (Figure S). The lower efficiency is because the high content will reduce the mobility of SA-g-DA chains necessary for the self-healing at molecular level. S-5

6 Figure S. Schematic illustration of the connection of capacitors in series. In order to light the LED bulb, capacitors were connected in series according to Figure S. The loading of each AC electrode was precisely controlled to ensure the long electrode was twice as heavy as the short electrode. Therefore, the resulting capacitor was equal to four capacitors connected in series and provided an output voltage about.7 V. (c) (d) (e) (f) Figure S9. (a-c) Recovery of electrical conductivity of the broken AC electrodes after the cut/healing operations, (d) microscopic images recording the contact of the broken AC electrodes at the region (top view), (e-f) cross-sectional images showing the contact of the broken AC electrodes through the formation of a small depression at the region. In this study, the self-healing of the hydrogel electrolyte induced the effective contact of the broken AC electrodes since they were tightly adhered to the electrolyte. Indeed, conductivity measurements showed that the electrodes only slightly increased their resistance from 157 Ω to 11 Ω after self-healing (Figure S9a-c). Microscopic images also revealed that the broken electrodes contact each other after self-healing, although there S-

7 was a gap between them (Figure S9d). The recovery of electronic conduction of the broken electrodes is because a small depression was formed at the region due to the slight dehydration of the electrolyte in the self-healing process (Figure S9e-f). The depression induced effective contact of the broken AC electrodes and thus rebuilt their electronic conducting path. Figure S1. Equivalent circuit used for fitting of the EIS spectra of the capacitor. L represents the inductance of elongation wire, R s is the electrolyte resistance, R ct is the charge transfer resistance, Z w is the Warburg impedance, C dl represents the double layer capacitance and C ps is the pseudocapacitance caused by the oxygen-containing functionalities of the AC electrodes and the SA-g-DA/KCl hydrogel electrolyte RT RT (c) o C o C 1-5 o C -5 o C -1 o C -1 o C Z'' (Ohm) 1 1 Z' (Ohm) -Z'' (Ohm) Z' (Ohm) -Z'' (Ohm) RT o C -5 o C -1 o C Z' (Ohm) Figure S11. EIS spectra of the hydrogel electrolytes with 1 mol L 1, mol L 1 and (c) mol L 1 KCl at low temperatures. S-7

8 Table S1. Comparison on the ionic conductivity of the typical hydrogel electrolytes reported in literatures. Polymeric Concentration of Ionic conductivity Self-healable Ref. Solute network solute (mol L 1 ) (ms cm 1 ) SA-g-DA KCl This work PVA KCl PAA KCl 1 1 PAA H PO NA 7.5 PAAK KCl 1 15 PVA H SO.5 5 PUA/PAAM Na SO.5 PVA KCl Table S. Comparison on the R s and R ct of the capacitor after multiple cut/healing cycles. Cut/healing cycle R s (Ω) R ct (Ω) Original st 1.7. rd th th th Table S. Comparison on the R s and R ct of the capacitor at different temperatures. Temperature ( o C) R s (Ω) R ct (Ω) S-

9 REFERENCES (1) Guo, Y.; Zhou, X.; Tang, Q.; Bao, H.; Wang, G.; Saha, P. A Self-Healable and Easily Recyclable Supramolecular Hydrogel Electrolyte for Flexible Supercapacitors. J. Mater. Chem. A 1,, () Wang, Z. K.; Tao, F.; Pan, Q. M. A Self-Healable Polyvinyl Alcohol-Based Hydrogel Electrolyte for Smart Electrochemical Capacitors. J. Mater. Chem. A 1,, () Huang, Y.; Zhong, M.; Huang, Y.; Zhu, M.; Pei, Z.; Wang, Z.; Xue, Q.; Xie, X.; Zhi, C. A Self-Healable and Highly Stretchable Supercapacitor Based on a Dual Crosslinked Polyelectrolyte. Nat. Commun. 15,, 11. () Lee, K. T.; Wu, N. L. Manganese Oxide Electrochemical Capacitor with Potassium Poly(acrylate) Hydrogel Electrolyte. J. Power Sources, 179,. (5) Wang, K.; Zhang, X.; Li, C.; Sun, X.; Meng, Q.; Ma, Y.; Wei, Z. Chemically Crosslinked Hydrogel Film Leads to Integrated Flexible Supercapacitors with Superior Performance. Adv. Mater. 15, 7, () Tang, Q.; Chen, M.; Wang, G.; Bao, H.; Saha, P. A Facile Prestrain-Stick-Release Assembly of Stretchable Supercapacitors Based on Highly Stretchable and Sticky Hydrogel Electrolyte. J. Power Sources 15,,. (7) Jiang, M.; Zhu, J.; Chen, C.; Lu, Y.; Ge, Y.; Zhang, X. Poly(Vinyl Alcohol) Borate Gel Polymer Electrolytes Prepared by Electrodeposition and Their Application in Electrochemical Supercapacitors. ACS Appl. Mater. Interfaces 1,, 7 1. S-9