Supporting Information

Transcription

1 Supporting Information Dynamic Crosslinking of Polymeric Binders Based on Host- Guest Interactions for Silicon Anodes in Lithium Ion Batteries Tae-woo Kwon,, You Kyeong Jeong,, Erhan Deniz, Siham Y. AlQaradawi, Jang Wook Choi,*, and Ali Coskun*,, Graduate School of EEWS and KAIST Institute NanoCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon , Republic of Korea Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon , Republic of Korea Department of Chemistry and Earth Sciences, College of Arts and Sciences, Qatar University, P.O. Box 2713, Doha, Qatar Professor Jang Wook Choi Graduate School of EEWS Korea Advanced Institute of Science and Technology (KAIST) 291 Daehak-ro, Yusung-gu, Daejeon , Republic of Korea. Tel: (+82) Fax: (+82) * Correspondence Address Professor Ali Coskun Graduate School of EEWS and Department of Chemistry Korea Advanced Institute of Science and Technology (KAIST) Guseong Dong, Yuseong Gu, Daejeon (Republic of Korea). Tel: (+82) Fax: (+82) coskun@kaist.ac.kr

2 Table of Contents Section 1. 1 H NMR Characterization of α, β, and γ-cdp s3 Section 2. Synthesis S7 Section 3. Gelation Experiments S14 Section 4. Host-Guest Inclusion Test S16 Section 5. Electrochemical Data......S17 Section 6. References S24 S2

3 Section 1. 1 H NMR Characterization of α, β, and γ-cdp 1 H NMR spectra of α, β, and γ-cdp (D 2 O, 300 MHz, 298K) were recorded to calculate the amounts of CD within CDp. While broad peaks at δ ppm were attributed to H 1 of CD, the peaks at δ ppm originated from H 2-6 protons of CD and glycerol protons. Since glycerol unit is the basic repeating unit of side chains, we assumed all side chains bear one glycerol unit. The OH peaks were not detected in the 1 H NMR spectra due to rapid proton exchange with deuterated water molecules. Glucopyranose unit of CD Glycerol Side chain Integrated peak area of glycerol was calculated by subtracting integrated area of CD from CDp in the range of δ ppm. Considering five protons (H 2-6 ) of CD and 5 protons of glycerol in the range of δ ppm, molar ratio of CD and glycerol was obtained, and it was then converted to CD wt% within CDp as shown below and Figure S1-3. Integrated Peak Areas CDp (H 2-6) CD (H 1) Glycerol (δ ppm) (δ ppm) (δ ppm) Molar Ratio (CD : Glycerol) CD (wt%) α : % β : % γ : % S3

4 Figure S1. 1 H NMR spectra of α-cd and α-cdp (D 2 O, 300 MHz, 298K). S4

5 Figure S2. 1 H NMR spectra of β-cd and β-cdp (D 2 O, 300 MHz, 298K). S5

6 Figure S3. 1 H NMR spectra of γ-cd and γ-cdp (D 2 O, 300 MHz, 298K). S6

7 Section 2. Synthesis Synthetic Procedure for 6AD and 1AD. Synthesis of Compound 1 3 [1] [2] Compounds 1-3 were synthesized according to the previously reported procedures. Synthesis of Compound 4 To a suspension of compound 3 (2.2 g, 1.99 mmol) in 50 ml of ethanol aqueous NaOH solution (4 ml, 5 M) was added. The mixture was then heated to reflux at 80 C for 3 days. The reaction mixture was cooled down to room temperature and poured into 40 ml of 1 M HCl solution and stirred for 10 min. The solution was extracted with CH 2 Cl 2 (3 x 20 ml). The combined organic layers were washed with brine (20 ml) and then dried over anhydrous Na 2 SO 4. The product was isolated as a brown oil and used without further purification. 1 H NMR (300 MHz, CDCl 3 ): δ = 7.39 (s, 2H), 4.23 (m, 6H), (m, 42 H), 2.13 (br, 3H), 1.75 (br, 6H), 1.61 (m, 6H); IR (cm -1 ): ν 3483, 2904, 2850, 1714, 1585, 1500, 1453, 1429, 1354, 1323, 1304, 1208, 1106, 1088, 979, 952, 868, 814, 770, 706. S7

8 Figure S4. 1 H NMR spectrum of Compound 4 (CDCl 3, 300 MHz, 298 K). Peaks marked by X indicate grease and tetramethylsilane. S8

9 Figure S5. FT-IR spectrum of Compound 4 and corresponding peak assignments of representative functional groups. ϕ refers to the phenylene moiety. S9

10 Synthesis of Compound 5 (6AD) Compound 4 (216.6 mg, mmol) was dissolved in DMF (0.6 ml). 1,2-Bis(2- aminoethoxy)ethane (14.6 mg, mmol), TBTU (O-(benzotriazol-1-yl)-N,N,N,N,- tetramethyluroniumtetra-fluoroborate) (50.5 mg, mmol) and Hünig`s base (diisopropylethylamine, 50.8 mg) were added to this mixture. The reaction mixture was stirred at room temperature for 25 h and subsequently quenched by addition of water (5 ml). The reaction mixture was then extracted with DCM (2 x 5 ml). The organic phase was washed with water (2 x 5 ml) and dried over Na 2 SO 4, filtered, evaporated to afford compound 5 as brown oil (83% yield). 1 H NMR (300 MHz, CDCl 3 ): δ = 7.10 (s, 4H, Ar-H), 6.92 (s, 2H, -CONH-), 4.18 (br, 12H, Ar-OCH 2 -), (m, 84H, -OCH 2 -), 2.13 (br, 3H, Adamantane), 1.73 (br, 6H, Adamantane), 1.61 (m, 6H, Adamantane); 13 C NMR (300 MHz, CDCl 3 ); δ = 166.7, 156.1, 152.4, 142.2, 129.6, 108.2, 81.3, 80.9, 80.4, 77.6, 77.2, 76.7, 75.4, 74.9, 74.2, 72.3, 71.7, 71.3, 70.5, 62.9, 59.3, 45.3, 41.5, 40.1, 36.4, 34.2, 30.5 ; IR (cm -1 ): ν 3361, 3083, 2904, 2850, 1652, 1640, 1580, 1541, 1495, 1453, 1425, 1365, 1352, 1330, 1304, 1291, 1240, 1106, 1088, 980, 951, 867, 814, 764, 748; HRMS (ESI): Calculated for C 128 H 204 N 2 Na 2 O 34 ([M + 2Na] 2+ ): , found: S10

11 Figure S6. 1 H NMR spectrum of Compound 5 (6AD) (CDCl 3, 300 MHz, 298 K). The peak marked by X indicates tetramethylsilane. S11

12 Figure S7. 13 C NMR spectrum of compound 5 (6AD) (CDCl 3, 300 MHz, 298 K). S12

13 Figure S8. FT-IR spectrum of Compound 5, 6AD, and the corresponding peak assignments of representative functional groups. ϕ refers to the phenylene moiety. S13

14 Section 3. Gelation Experiments In water: Preparation of β-cdp/6ad gel: β-cdp and 6AD (CD: AD, 1:1 stoichiometry) was dissolved in DMF to form the inclusion complex, followed by the removal of DMF at 80 o C under vacuum over 12 h. The resulting inclusion complex was redissolved in H 2 O to form a yellow colored gel. Final concentrations of β-cdp and 6AD are 0.7 g ml -1 (300 mm) and 0.11 g ml - 1 (50 mm), respectively. Preparation of β-cdp: β-cdp was dissolved in H 2 O to reach final concentration of 0.7 g ml -1 (300 mm). No gelation was observed in the absence of 6AD. Figure S9. Photographic images of the aqueous mixture of β-cdp (0.7 g ml -1, 300 mm) / 6AD (0.11 g ml -1, 50 mm) and β-cdp aqueous solution (0.7 g ml -1, 300 mm). While β- CDp/6AD mixture can form a strong gel as evidenced by the tube inversion test, β-cdp alone only formed a viscous liquid. S14

15 Gelation tests in organic media: In order to demonstrate the gel formation in organic media, we have carried out (Figure S10) gelation experiment for β-cdp/6ad mixture in polar organic solvents such as DMSO and electrolyte/dmso. Figure 10a shows the photographic images of tube inversion test for the mixtures of α-cdp and β-cdp with 6AD in DMSO. This result clearly shows the formation of gel in organic media in the case of β-cdp/6ad. In order to mimic electrolyte conditions, we have carried out (Figure S10b) the same gelation experiment in electroyte/dmso (70/30 v%) mixture. We added to DMSO in order to increase the solubility of both α-cdp and β- CDp. It is also important to note that electrolyte (4.9 D) has higher dielectric constant compared to that of DMSO (3.96 D), thus should favor the formation of inclusion complex. As expected, we still observed gel formation in electrolyte/dmso mixture. α-cdp/6ad mixture resulted in the formation of a viscous liquid in both DMSO and electrolyte/dmso mixture, thus further supporting the fact that gelation in the case of β-cdp/6ad is due to host-guest complex formation. (a) DMSO (b) Electrolyte/DMSO α- or β-cdp 0.07 g 0.07 g 6AD g g Solvent 100 ul 70 ul / 30 ul Figure S10. Photographic images of the tube inversion test for α-cdp/6ad and β-cdp/6ad mixtures in (a) DMSO and (b) electrolyte/dmso (70/30 v%). S15

16 Section 4. Host-guest complex formation in the electrolyte Preparation of Samples: To a 5.1 mg of 6AD solution in 0.4 ml of electrolyte (EC:DEC=1:1 v/v), 30 mg of α-cdp or β-cdp was added and stirred for 30 min. Resulting gel-like precipitate was filtrated and washed with 10 ml of electrolyte to remove any uncomplexed 6AD. Collected polymer was fully dried and analyzed using 1 H NMR spectroscopy. In the case of α-cdp, we haven t observed any peaks associated with the adamantane protons of 6AD in the range of ppm (Figure S11a), indicating that there is no complexation between α-cdp and 6AD in the electrolyte. In the case of β-cdp, however, we have observed corresponding adamantane protons (Figure S11b), indicating clearly that β-cdp can still form an inclusion complex with 6AD in the electrolyte. It is also noteworthy that we observed slight downfield shift of adamantane protons to 2.078, 1.647, and ppm, which reflects the formation inclusion complex. Figure S11. 1 H NMR spectra (d 6 -DMSO, 300 MHz, 298 K) of (a) α-cdp/6ad and (b) β- CDp/6AD after washing with electrolyte (EC:DEC = 1:1 v/v) along with the 1 H NMR spectra of 6AD, α- and β-cdp and electrolyte. S16

17 Section 5. Electrochemical Data Preparation of Si slurry and electrodes: For comprehensive understanding of the crosslinking effect between β-cdp and 6AD on the electrochemical performance, we have varied the amount of 6AD while keeping the amount of β-cdp (20 mg) constant. β-cdp (20 mg) was first dissolved in 0.5 ml of DI water on a mortar, followed by adding the corresponding amount of 6AD ethanol solution (d=0.017) ( wt%). No aggregation was observed in this dilute condition. Si (60 mg) and SuperP (20 mg) was successively added and mixed for at least 20 min to afford homogeneous slurry. Detailed binder compositions are as follows; Table S1. Binder conditions Binder Linker Amount of linker (mg) Weight % of 6AD β-cdp (20mg fixed) 6AD wt% 8.5 wt% 17.0 wt% 25.5 wt% We have also carried out control experiments with α- and γ-cdp, wherein 8.5 wt% of 6AD were added into each of 20 mg of α-cdp and γ-cdp dissolved in 0.5 ml DI water. Likewise, Si NP (60 mg) and SuperP (20 mg) were put into these mixtures. Table S2. Binder conditions Binder Linker Amount of linker (mg) Weight % of 6AD α-cdp 6AD wt% γ-cdp 6AD wt% S17

18 In order to demonstrate the effect of crosslinking, we also carried out control experiments with 1AD. 8.5 wt% of 1AD was added into each of 20 mg of α-cdp, β-cdp, and γ-cdp. Si NP (60 mg) and SuperP (20 mg) were put into these mixtures. Table S3. Binder conditions Binder Linker Amount of linker (mg) Weight % of 1AD α-cdp 1AD wt% β-cdp 1AD wt% γ-cdp 1AD wt% All slurry mixtures were uniformly cast onto Cu foil to a thickness of ~120 µm by using the doctor blade method. These electrodes were thoroughly dried at 50 C in oven for 12 h, and also under vacuum for 30 min before the cell assembly. Then all the dried electrodes were cut into 12 phi round shape. S18

19 Figure S12. (a) Galvanostatic measurement of β-cdp/6ad (8.5%) only film at 1µA cm -2. (b) The same sample measured by CV at 0.2 µv s -1. S19

20 Figure S13. Voltage profiles of Si electrodes incorporating (a) α-cdp, α-cdp/1ad and α- CDp/6AD, (b) β-cdp, β-cdp/1ad and β-cdp/6ad and (c) γ-cdp, γ-cdp/1ad and γ- CDp/6AD as binders at 0.1C (300 ma g -1 ) rate in the range of V vs. Li/Li + at 25 o C. Figure S14. Cycle performance of Si electrodes incorporating (a) α-cdp and (b) γ-cdp as hosts and 1AD & 6AD as guest molecules at 0.5C (1500 ma g -1 ) rate in the range of V vs. Li/Li + at 25 o C. S20

21 Figure S15. Rate performance of Si electrode including β-cdp/6ad (0.1C = 300 ma g -1 ). Figure S16. Cyclic voltammogram of Si/β-CDp/6AD (8.5 wt%) at 30 µv s -1. S21

22 Figure S17. FT-IR spectra of β-cdp/6ad (8.5 wt%) before and after 10 cycles. Amide I band of 6AD at 1640 cm -1 remains intact after 10 cycles. The bands denoted as * are attributed to the electrolyte. S22

23 Figure S18. SEM images of the same spot of the Si electrode based on β-cdp/6ad after the 1 st cycle and after the 2 nd cycle at 0.1C rate. Cracks created after the 1 st cycle are self-healed during the 2 nd cycle. S23

24 Section 6. References [1] Mulder, A.; Auletta, T.; Sartori, A.; Del Ciotto, S.; Casnati, A.; Ungaro, R.; Huskens, J.; Reinhoudt, D. N. Divalent Binding of a Bis(adamantyl)-Functionalized Calix[4]arene to β- cyclodextrin-based Hosts: An Experimental and Theoretical Study on Multivalent Binding in Solution and at Self-Assembled Monolayers. J. Am. Chem. Soc. 2004, 126, [2] Zhang, Y. R.; Tu, Q.; Wang, D. E.; Chen, Y.; Lu, B. Z.; Yuan, M. S.; Wang, J. Y. Adamantyl-terminated Dendronized Molecules: Synthesis and Interaction with β- Cyclodextrin-functionalized Poly(dimethylsiloxane) Interface. New. J. Chem. 2013, 37, S24