Novel (Blend) AEMs and Their Application in DMFC

Size: px

Start display at page:

Download "Novel (Blend) AEMs and Their Application in DMFC"

Dulcie Paul
6 years ago
Views:

1 ovel (Blend) AEMs and Their Application in DMFC Jochen Kerres, Anika Katzfuß AEM for Energy Generation Technologies Workshop, University of Surrey Universität Stuttgart, Institut für Chemische Verfahrenstechnik (ICVT), Stuttgart, Germany

2 Outline AEM Based Onto BrPPO AEM Based Onto MPBIOO, PSUSO 2 Li, DABCO and DIB 2

3 Outline AEM Based Onto BrPPO AEM Based Onto MPBIOO, PSUSO 2 Li, DABCO and DIB 3

4 Prepolymer I for AEM Bromination of PPO CH 2 Br * O * Solvent BS, 24 h, AIB * O * CH 2 Br Green chemistry! Using BS insteed of bromine! Substitution only at the side chain, not on the aromatic ring! theo. Substitution [%] exp. Substitution [%] Yield [%] Xu Tongwen, Yang Weihua, Journal of Membrane Science 190 (2001) A. Katzfuß, V. Gogel, L. Jörissen, J. Kerres, J. Membr. Sci (2013)

Concept of Covalent Crosslinking of AEM FG = functional groups ; DABCO as diamen to introduce simultaneously a covalent crosslink and a quaternary ammonium group CG =

5 Concept of Covalent Crosslinking of AEM FG = functional groups ; DABCO as diamen to introduce simultaneously a covalent crosslink and a quaternary ammonium group CG = conducting groups Leads high crosslinking degree to increasing IEC-values and conductivity? [1] B. Bauer, H. Strathmann, F. Effenberger, Desalination 79 (1990)

6 Embedding into Matrix Polymer Pure AEM based onto BrPPO, DABCO and DIB (F and G Membranes) are too brittle at large bromination degree Addition of PVDF as a matrix polymer * H 2 C * CF 2 n Mechanically stable membranes are obtained

Covalent Crosslinking Widening of OH - -Conductive Channels F-type: BrPPO + DABCO G-type:. BrPPO + DABCO + DIB Membran Crosslinking theo. [%] Crosslinking exp.

7 Covalent Crosslinking Widening of OH - -Conductive Channels F-type: BrPPO + DABCO G-type:. BrPPO + DABCO + DIB Membran Crosslinking theo. [%] Crosslinking exp. [%] IEC total [meq/g] G F F ,1 F ,0 F ,7 G ,1 G ,9 G ,6 High reactivity between BrPPO + DABCO Higher crosslinking but lower IEC-value

in KOH Within the first days the IEC value increases

8 Alkaline Stability IEC Values of F and G Type Membranes During KOH Treatment Before immersion in KOH After immersion in KOH Within the first days the IEC value increases slightly After 10 days IEC value decrease of F-type, stable IEC of G-type

9 Alkaline Stability Conductivity Values During KOH Treatment Conductivities remain in the same range Difference in crosslinking degree has influence on the conductivity DABCO-BrPPO bond is obviously not severely attacked by hydroxide ions Mechanical stability decreases, because the matrix polymer PVDF degrades (F - detection) Search for alternative matrix polymers required 9

10 DMFC Application Passive DMFC at RT Passive DMFC cell, selfbreathing, 4 M MeOH + 1 KOH as electrolyte, 4 ml/min, 25 C GDE from gaskatel; Anode: 2.5 mg/cm 2 Pt/C; Cathode: Ag/AgO on nickel gauze Increasing crosslinking degree decreases the UI-curve Only 6% difference in crosslinking degree between F1 and F3 leads to doubling of power density (8% G1 to G3) 10

11 DMFC Application Active DMFC at 80C(at ZSW Ulm) Active DMFC cell, 2 ml/min, 80 C Anode: 5 mg/cm 2 Pt/Ru/C mit 10% PTFE ; Cathode: 5 mg/cm 2 Pt/C mit 10% PTFE Conditions: a) 1 M MeOH / 1 M KOH; b) 1 M MeOH / 5 M KOH; c) 4 M MeOH / 5 M KOH F1 A006 a) 1 M MeOH / 1 M KOH; b) 1 M MeOH / 5 M KOH; c) 4 M MeOH / 5 M KOH Results for the different DMFC conditions: a) UI-curve is low b) strong increase c) no influence at F1 membrane c) A006: decrease of UI-curve because of MeOH crossover 11

12 DMFC Application Active DMFC at 80C(at ZSW Ulm) UI curve of F1 and A006 using 4 M MeOH / 5 M KOH electrolyte - 2 ml/min; 80 C; -Anode: 5 mg/cm 2 Pt/Ru/C with 10% PTFE ; -Cathode: 5 mg/cm 2 Pt/C with 10% PTFE F1 is better than commercial A006 membrane

13 Outline AEM Based Onto BrPPO AEM Based Onto MPBIOO, PSUSO 2 Li, DABCO and DIB 13

14 Prepolymer II for AEM Methylation of PBIOO Shieh et al performed methylation of benzimidazoles without methyl iodide [2-4] For the first time transfer of this low-molecular reaction to polymers Methylation of PBI without using toxic methyl iodide! Using Dimethylcarbonate and DABCO H O * O * H DMC, DABCO 145 C, 96 h O CH 3 * O * CH 3 [2] W. Shieh, S. Dell, O. Repic, Org. Lett. 3(26) (2001) [3] W. Shieh, M. Lozanov, M. Loo, O. Repic, T.J. Blacklock, Tetrahedron Lett. 44 (2003) [4] W. Shieh, S. Dell, A. Bach, O. Repic, T.J. Blacklock, J. Org. Chem. 68 (2003)

15 Membranes from mpbioo Quaternization of PBIOO with Diiodobutane (DIB) and DABCO CH 3 Add DIB + DABCO * O O * CH 3 I DIB DABCO (H2C)4 O CH 3 * O * CH 3 I (CH2)4 I I Strong inhomogeneity O (H2C)4 CH 3 I * * O CH 3

16 Membranes from mpbioo Addition of a Second Polymer: Sulfinated PSU Adding DIB + DABCO + PSU-SO 2 Li CH 3 O * O * CH 3 +DABCO + DIB Membranes are homogenious and flexible IEC-values between 2.0 and 2.8 meq/g possible Membranes called BAK 39

17 Membranes from mpbioo and PSU-SO 2 Li Variation of the Cross-Linking Degree Dependence of the insolubles percentage (crosslinking degree) on the temperature Temperature [ C] Crosslinking degree* [%] IEC [meq/g] *insolubles content The higher the temperature during solvent evaporation, the higher the %insolubles content (crosslinking degree) of the blend membranes.

18 Alkaline Stability of Type II AEM Immersion of samples in 1 KOH at 90 C After different immersion times the IEC values and conductivity were determined. IEC and Conductivity During KOH Treatment BAK 39 membranes with various crosslinking degrees The IEC values and the conductivity are very stable until 7 days. After 10 days the properties slightly decrease The membranes remains flexible in the mechanical stability. BAK 39 membrane has superior alkaline stability. 18

19 Comparison of Type I and Type II Membranes Comparison of MeOH Uptake Immersion of samples in 4 M MeOH at different temperatures for 24 h BAK 39 membrane F- and G-type membrane The higher the crosslinking degree, the lower the MeOH uptake Tokuyama A006 membrane has the highest MeOH uptake from all tested samples. Very low MeOH uptake of all samples High hydrophobicity of G because of using additional DIB Reaching highest uptake at 25 C 19

20 Comparison of Type I and Type II Membranes Comparison of DMFC Performance (RT) Passive DMFC cell, selfbreathing, 4 M MeOH + 1 KOH as electrolyte, 4 ml/min, 25 C GDE from gaskatel; Anode: 2.5 mg/cm 2 Pt/C; Cathode: Ag/AgO on nickel gauze F1 and G1 equal to commercial A006 membrane from Tokuyama BAK 39 membrane worse in the passive DMFC 20

21 Comparison of Type I and Type II Membranes Comparison of the developed membranes with A006 Usage of non-pt catalyst - 2 ml/min 4 M MeOH, 5 M KOH; 80 C -Anode: 6% Pd/CeO 2 /C ; Cathode: 4% FeCo/C All samples are equal maximum power density of 130 mw/cm 2 is reached! 21

22 Conclusions and Outlook Development of two different AEM systems One is based on BrPPO, the other on methylated PBIOO Both are very stable under alkaline conditions Influence of different crosslinking degree was shown The higher the crosslinking degree, the lower the IEC value, conductivity and methanol uptake Power density of 130 mw/cm 2 reached! Search for other matrix polymers (including other alkylated PBIs) Use of different diamines and dihalogenes Longlife stability tests in DMFC 22

23 Acknowledgement My group: K. Aniol, V. Atanasov, A. Carlsson, A. Chromik, I. Hajdok, A. Katzfuss, I. Kharitonova, G. Schumsky, C. Seyb Funding: AiF: Joint Project ovel stable anion-exchange membranes and MEAs for alkaline fuel cells AiF: Joint Project Alkaline Electrolysis with ovel AEMs 23

The Blend Concept: From Low-T Cation- Exchange to High-T Cation-Exchange to Anion-Exchange Membranes

The Blend Concept: From Low-T Cation- Exchange to High-T Cation-Exchange to Anion-Exchange Membranes The Blend Concept: rom Low-T Cation- Exchange to igh-t Cation-Exchange to Anion-Exchange Membranes Jochen Kerres Institute of Chemical Process Engineering (ICVT), University of Stuttgart, Stuttgart, Germany