Porous nano-fiber mats to reinforce proton conducting membranes for PEM applications
View Patent ↗A method of manufacturing a proton conducting fuel cell composite membrane includes the step of electrospinning a non-charged polymeric material, such as PVDF and PSF, into fiber mats. The fibers are fused to one another to provide a welded porous mat. The welded porous mat is filled with proton conducting electrolyte, such as PFSA polymer, to generate a proton conducting composite membrane. The resulting proton conducting fuel cell membrane comprises a randomly oriented, three dimensional interlinked fiber lattice structure filled with proton conducting electrolyte, such as PFSA polymer.
1. A method of manufacturing a proton conductive fuel cell membrane comprising:
electrospinning a non-charged polymeric material into a fiber mat;
fusing fibers to one another to provide a welded porous mat, the fusing including interlinking the fibers to one another at fiber intersections using solvent vapor welding for between five minutes to thirty minutes and at temperatures between 50° C. to 70° C.; and
filling the welded porous mat with a proton conducting polymer solution, to provide a proton conducting composite membrane for use in electrochemical cells.
2. The method according to claim 1 , wherein the electrospinning includes producing the fiber mat which has an average fiber diameter in a range of 100-1150 nm, a mat thickness in a range of 10-100 μm, and a mat porosity in a range of 40-95%.
3. The method according to claim 2 , wherein the average fiber diameter is 100-600 nm.
4. The method according to claim 2 , wherein the polymeric material includes at least one of PVDF and PSF.
5. The method according to claim 2 , wherein the electrospinning includes dissolving the polymeric material in mixture solvents including DMAc.
6. The method according to claim 5 , wherein the electrospinning includes selecting polymeric material concentration, solvent ratio, voltage, spinneret-to-collector distance and polymeric material solution flow to produce fibers in the range without beads or droplets.
7. The method according to claim 6 , wherein a polymeric material concentration is 12-25%, a solvent ratio is 50-100% solvent in a mixture including acetone, a voltage of 5-15 kV, a spinneret-to-collector distance of 7-15 cm and a polymeric material solution flow rate of 0.1-0.3 mL/hour.
8. The method according to claim 1 , further comprising randomly orienting the fibers in three dimensions.
9. The method according to claim 1 , wherein the welded porous mat includes porosity in a range of 40-95%.
10. The method according to claim 1 , wherein the fibers are solvent vapor welded at approximately 60° C. for approximately 15 minutes in DMF vapor.
11. The method according to claim 1 , wherein a solvent is any one, or mixture, of dimethylacetamide, tetramethyl urea, dimethyl sulfoxide, triethyl phosphate, N-methyl-2-pyrrolidone, trimethyl phosphate, Tetrahydrofuran (THF), Methyl Ethyl Ketone.
12. The method according to claim 1 , wherein the welded porous mat includes opposing sides, and the filling includes exposing one of the sides to a solution containing a fluoropolymer having a proton conducting group, and then exposing the other side to the solution.
13. The method of claim 1 wherein the fusing includes interlinking the fibers to one another at fiber intersections using solvent vapor welding for less than fifteen minutes and at a temperature below 60° C.