Porous electrolyzer gas diffusion layer and method of making thereof

Abstract

A porous titanium sheet configured to function as an anode side gas diffusion layer of a proton exchange membrane (PEM) electrolyzer is formed by a powder technique, such as tape casting or powder metallurgy.

What is claimed is: 
     
         1 . A method for making a porous titanium sheet, the method comprising:
 forming a slip material from a titanium-containing powder mixture with a binder, solvent, and plasticizer;   dispensing the slip material onto a moving tape carrier web;   flattening the slip material dispensed on the tape carrier web into a green titanium-containing tape using a doctor blade;   drying the green titanium-containing tape;   cutting the green titanium-containing tape into a first titanium green sheet; and   forming the porous titanium sheet that facilitates proton exchange for an anode side gas diffusion layer, the porous titanium sheet formed by sintering the first titanium green sheet.   
     
     
         2 . The method of  claim 1 , wherein the titanium-containing powder mixture includes elemental titanium and titanium hydride. 
     
     
         3 . The method of  claim 2 , wherein sintering the first titanium green sheet includes thermally converting the titanium hydride to elemental titanium in an exothermic reaction. 
     
     
         4 . The method of  claim 1 , further comprising adding a pore former material to the slip material prior to dispensing the slip materials onto the tape carrier web. 
     
     
         5 . The method of  claim 4 , wherein sintering includes removing the pore former material to form pores in the porous titanium sheet. 
     
     
         6 . The method of  claim 1 , wherein the steps of flattening, drying, cutting and forming by sintering concurrently occur on the moving tape carrier web. 
     
     
         7 . The method of  claim 1 , further comprising placing a second titanium green sheet having a porosity different from a porosity of the first titanium green sheet on the first titanium green sheet prior to the sintering. 
     
     
         8 . The method of  claim 7 , wherein the first titanium green sheet and the second titanium green sheet are sintered while in contact with each other such that a first major side of the porous titanium sheet has a higher porosity than an opposite second major side of the porous titanium sheet. 
     
     
         9 . The method of  claim 1 , wherein the titanium-containing powder has an average diameter less than 50% of a thickness of the porous titanium sheet. 
     
     
         10 . The method of  claim 1 , wherein the titanium-containing powder further comprises titanium-containing particles having an average diameter that is within 20% of a thickness of the porous titanium sheet or titanium-containing wires having an average length that is within 20% of the thickness of the porous titanium sheet. 
     
     
         11 . The method of  claim 10 , wherein the titanium-containing particles or the titanium-containing wires extend through an entire thickness of the porous titanium sheet. 
     
     
         12 . The method of  claim 1 , further comprising annealing the first titanium green sheet to remove an organic lubricant from the titanium green sheet. 
     
     
         13 . The method of  claim 1 , wherein sintering includes reactively sintering the porous titanium sheet in a nitrogen-containing atmosphere to form a titanium nitride coating on at least one surface of the porous titanium sheet. 
     
     
         14 . The method of  claim 1 , further comprising placing the porous titanium sheet into a PEM electrolyzer. 
     
     
         15 . A method for making a porous titanium sheet comprising:
 providing a mixture of titanium powder and lubricant into a die cavity;   compressing the mixture of titanium powder and lubricant in the die cavity to form a titanium green sheet;   de-binding the titanium green sheet; and   forming the porous titanium sheet that facilitates proton exchange for an anode side gas diffusion layer, the porous titanium sheet formed by sintering the titanium green sheet.   
     
     
         16 . The method of  claim 15 , wherein sintering includes reactively sintering the porous titanium sheet in a nitrogen-containing atmosphere to form a titanium nitride coating on at least one surface of the porous titanium sheet. 
     
     
         17 . The method of  claim 15 , further comprising placing the porous titanium sheet into a PEM electrolyzer. 
     
     
         18 . The method of  claim 15 , wherein the titanium powder includes titanium-containing particles having an average diameter that is within 20% of a thickness of the porous titanium sheet or titanium-containing wires having an average length that is within 20% of the thickness of the porous titanium sheet. 
     
     
         19 . The method of  claim 18 , wherein the at least one of the titanium-containing particles or the titanium-containing wires extend through an entire thickness of the porous titanium sheet.