Composition for fuel cell membranes and a process for the preparation thereof

Patent metadata

Field	Value
Publication number	US-12237552-B2
Application number	US-202017613626-A
Country	US
Kind code	B2
Filing date	May 26, 2020
Priority date	May 27, 2019
Publication date	Feb 25, 2025
Grant date	Feb 25, 2025

Abstract

The present invention relates to a composition for fuel cell membranes and a process for the preparation thereof. In particular, the present invention relates to thermo-mechanically and chemically stable polymer electrolyte membranes which have been prepared without compromising proton conductivity by using multifunctional polydopamine and mechanically robust nanocellulose.

First claim

The invention claimed is:

1. A process for preparing a composition for fuel cell membranes, wherein the composition comprises Nafion and 3 wt % of cellulose nanofibers coated with a polydopamine coating, wherein the polydopamine coating on the cellulose nanofibers is from 10% to 12% of a total weight of the cellulose nanofibers coated with the polydopamine coating, the process comprising:
(a) preparing cotton rag nanocellulose (CNF) by treating cleaned cotton rag pieces with 10% sodium hydroxide solution followed by deionized water [DI], bleaching the cotton rag with acetate buffer and 1.5 wt % sodium hypochlorite, followed by refining to a fine pulp using valley beater, followed by grinding in an ultrafriction microgrinder to obtain cotton rag nanocellulose;
(b) preparing polydopamine (PDA) by dispersing dopamine hydrochloride monomer 0.5-2 mg/mL in tris-buffer solution under stirring at 70-90° C. for 20-30 hr and lyophilizing to obtain polydopamine (PDA);
(c) preparing polydopamine coated nanocellulose (PNC) by dispersing 2 mg/mL cotton rag nanocellulose (CNF) as prepared by (a) in tris-buffer solution of pH 8.5 under stirring for 10 hours to 12 hours at 25° C. at a speed of 500 rpm and bath sonication for 15 minutes to 20 minutes to obtain a dispersed nanocellulose solution; followed by adding dopamine hydrochloride monomer into the dispersed nanocellulose solution in a ratio of dopamine to nanocellulose from 1:4 to 1:1 and stirring at 70° C. to 90° C. for 20 hours to 30 hours, followed by lyophilizing to obtain polydopamine coated nanocellulose (PNC);
(d) preparing Nafion solution by cutting Nafion membranes into small pieces and dissolving in a 24:1 (v/v) mixture of isopropyl alcohol and ethyl alcohol by stirring at a temperature from 25° C. to 30° C. and at a speed of 500 rpm;
(e) preparing a homogeneous dispersion of CNF or PDA or PNCs as obtained from (a), (b), and (c) by stirring and sonicating in a 24:1 (v/v) mixture of isopropyl alcohol and ethyl alcohol by stirring at a temperature from 25° C. to 30° C. and at a speed of 500 rpm with periodic bath sonication for 2 hours to 3 hours followed by adding pre-dispersed CNF or PDA or PNC solution into pre-dissolved Nafion solution as obtained from (d) and mixing well by vortex mixing and stirring at 30° C. temperature and at a speed of 500 rpm, degassing the solution and casting in a glass petri dish to afford a 3 wt % CNF/Nafion membrane or a 3 wt % PDA/Nafion membrane or a 3 wt % PNC/Nafion membrane, wherein all the membranes at dry conditions have a thickness of 40 μm to 55 μm when measured at five random locations.

Assignees

• Council Scient Ind Res

Inventors

• Shanmuganathan Kadhiravan
• Ram Farsa
• Lele Ashish Kishore

Classifications

• H01M2300/0091

  in the form of mixtures · CPC title

• H01M2300/0082

  Organic polymers · CPC title

• H01M2008/1095

  Fuel cells with polymeric electrolytes · CPC title

• H01M8/1067

  characterised by their physical properties, e.g. porosity, ionic conductivity or thickness · CPC title

• H01M8/1039

  halogenated, e.g. sulfonated polyvinylidene fluorides · CPC title