Electrically isolated electrochemical cell and method of manufacturing the same

Abstract

The present application relates to components for use in an electrolysis cell and/or stack comprising features, geometry, and materials to overcome prior art limitations related to cell electrical isolation, fluid sealing, and high speed manufacturing. The electrolysis cell comprises a membrane, an anode, a cathode, an anode flow field, a cathode flow field, and a bipolar plate assembly comprising an embedded hydrogen seal and both conductive and non-conductive areas. The components are cut using two-dimensional patterns from substantially flat raw materials capable of being sourced in roll form. These substantially two-dimensional components are processed to create a fully unitized, three-dimensional electrolysis cell with a hermetically sealed cathode chamber.

What is claimed is: 
     
         1 . An electrolysis cell comprising:
 a membrane,   an anode,   a cathode,   an anode flow field,   a cathode flow field,   a bipolar plate assembly, and   a liquid plenum fluidically connected to an electrically conductive area of the electrolysis cell, wherein the electrolysis cell comprises a cell pitch.   
     
     
         2 . The electrolysis cell of  claim 1 , wherein a conductive path in the liquid plenum between the electrically conductive area of the electrolysis cell and an electrically conductive area of an adjacent electrolysis cell is at least 1.5 times the cell pitch, 2 times the cell pitch, 3 times the cell pitch, 5 times the cell pitch, or 10 times the cell pitch. 
     
     
         3 . The electrolysis cell of  claim 1 , further comprising a nonconductive edge bounding at least a portion of the liquid plenum, wherein the nonconductive edge comprises an edge extension arranged between a conductive area of the electrolysis cell and the liquid plenum. 
     
     
         4 . The electrolysis cell of  claim 3 , wherein the length of the edge extension is at least 0.25 times the cell pitch, 0.5 times the cell pitch, 1 times the cell pitch, 2 times the cell pitch, or 5 times the cell pitch. 
     
     
         5 . A cell stack comprising a plurality of integrated electrolytic cells, each electrolytic cell comprising a conductive central area and a non-conductive edge area, wherein the non-conductive edge area comprises a plurality of water plenums in fluid communication with water plenums of adjacent cells in the cell stack, wherein the non-conductive edge area comprises an edge extension length arranged between the conductive area of each electrolysis cell and the water plenum. 
     
     
         6 . The cell stack of  claim 5 , wherein the edge extension is at least 0.25 times the cell pitch, 0.5 times the cell pitch, 1 times the cell pitch, 2 times the cell pitch, or 5 times the cell pitch. 
     
     
         7 . The cell stack of  claim 5 , wherein a conductive path between the conductive central areas of adjacent cells in the cell stack along the edge extension length and via a plenum is at least 1.5 times the cell pitch, 2 times the cell pitch, 3 times the cell pitch, 5 times the cell pitch, or 10 times the cell pitch. 
     
     
         8 . An electrolysis cell comprising:
 a membrane,   an anode,   a cathode,   an anode flow field,   a cathode flow field,   a bipolar plate assembly, and   a nonconductive edge   wherein the electrolysis cell is hermetically sealed against the environment and against cross-leakage between the cathode and the anode without use of compressible seals or gaskets.   
     
     
         9 . A bipolar plate assembly for an electrochemical cell comprising
 a conductive impermeable sheet, a conductive porous sheet, and a non-conductive, gas-tight, thermoplastic sheet, wherein the non-conductive thermoplastic sheet and extends beyond the conductive sheets along an x-axis and comprises water plenums spaced from the conductive sheets by an edge extension length.   
     
     
         10 . The bipolar plate assembly of  claim 9 , wherein the nonconductive thermoplastic sheet is bonded to the conductive impermeable sheet and the conductive porous sheet to create a hermetic seal against the environment. 
     
     
         11 . The bipolar plate assembly of  claim 9 , wherein the nonconductive thermoplastic sheet is flowed into the conductive porous sheet to create an embedded gas seal against the environment. 
     
     
         12 . The bipolar plate assembly of  claim 9 , wherein the conductive impermeable sheet is etched or chemically treated to promote bonding. 
     
     
         13 . The bipolar plate assembly of  claim 9 , wherein the nonconductive thermoplastic sheet is a hot melt. 
     
     
         14 . The bipolar plate assembly of  claim 9 , wherein the nonconductive thermoplastic sheet is UV cross-linkable to enhance high temperature mechanical properties in-situ. 
     
     
         15 . The bipolar plate assembly of  claim 9 , wherein the nonconductive thermoplastic sheet comprises a low elastic modulus material. 
     
     
         16 . The bipolar plate assembly of  claim 9 , wherein the conductive impermeable sheet, conductive porous sheet, and a non-conductive thermoplastic sheet are joined, shaped, or finished with an approach selected from the group consisting of roll lamination, laser/die cutting, laser etching, integrated TPE slug recycling, and UV cross-linking, and combinations thereof. 
     
     
         17 . The bipolar plate assembly of  claim 9 , wherein the conductive impermeable sheet and the conductive porous sheet are comprised sheet material having substantially uniform thickness capable of being sourced in roll or coil form. 
     
     
         18 . A membrane sub-gasket assembly for an electrochemical cell comprising
 an ionically conductive membrane layer, and   at least one reinforcement border layer,   wherein the border layer comprises a hot-melt thermoplastic material which is cross-linkable via exposure to UV light.   
     
     
         19 . The membrane sub-gasket assembly of  claim 18 , wherein the ionically conductive membrane layer and the at least one reinforcement border layer are hermetically bonded in an overlap region to provide an internal cell between hydrogen and oxygen and to provide mechanical reinforcement to the membrane in the internal seal region. 
     
     
         20 . The membrane sub-gasket assembly of  claim 18 , wherein the at least one reinforcement border layer is cross-linked after integration into an electrolytic cell to enhance high temperature mechanical properties in-situ. 
     
     
         21 . The membrane sub-gasket assembly of  claim 19 , wherein UV cross-linking occurs post web lamination and slug recycling to allow processing at low temperatures for manufacturing while achieving necessary in-situ mechanical properties. 
     
     
         22 . The membrane sub-gasket assembly of  claim 19 , wherein the at least one reinforcement border layer is subjected to a thermal decomposition step to enhance bonding with an adjacent component or layer. 
     
     
         23 . A half-cell assembly for an electrochemical cell comprising
 a bipolar plate assembly according to  claim 9 ,   a cathode electrode, and   a membrane sub-gasket assembly for an electrochemical cell comprising an ionically conductive membrane layer, and at least one reinforcement border layer, wherein the border layer comprises a hot-melt thermoplastic material which is cross-linkable via exposure to UV light.   
     
     
         24 . The half-cell assembly of  claim 23 , wherein the membrane sub-gasket assembly is hot melt sealed to the bipolar plate assembly, thereby completely encapsulating the cathode electrode within a hermetically sealed hydrogen region. 
     
     
         25 . The half-cell assembly of  claim 24 , wherein a hot melt seal is formed between the sub-gasket assembly and a hydrogen seal of the bipolar plate assembly. 
     
     
         26 . The half-cell assembly of  claim 25 , wherein the hot melt seal is formed from thermoplastic materials having compatible properties to allow homogeneous mixing at the interface during hot melt processing thereby eliminating a potential bond line between layers after processing. 
     
     
         27 . An anode-gasket assembly for an electrochemical cell comprising
 a water seal,   anode electrode, and   an anode flow field,   wherein the water seal comprises a thermoplastic material.   
     
     
         28 . The anode-gasket assembly of  claim 27 , wherein the thermoplastic material is hot bonded to the water seal, anode electrode, and anode flow field such that the components form a unitized assembly for accuracy in component alignment and ease of handling in manufacturing. 
     
     
         29 . The anode-gasket assembly of  claim 27 , wherein the thermoplastic material is a hot melt thermoplastic material. 
     
     
         30 . The anode-gasket assembly of  claim 27 , wherein the thermoplastic material is UV cross-linkable to enhance high temperature mechanical properties in-situ. 
     
     
         31 . The anode-gasket assembly of  claim 27 , wherein the thermoplastic material comprises a low elastic modulus. 
     
     
         32 . The anode-gasket assembly of  claim 30 , wherein UV cross-linking occurs post lamination and post-slug recycling to allow processing at low temperatures for manufacturing while achieving necessary in-situ mechanical properties. 
     
     
         33 . An integrated cell assembly comprising
 a half-cell assembly according to  claim 23 , and   an anode-gasket assembly for an electrochemical cell comprising a water seal, anode electrode, and an anode flow field, wherein the water seal comprises a thermoplastic material.   
     
     
         34 . The integrated cell assembly of  claim 33 , wherein the half-cell assembly and anode gasket assembly are hot bonded into a unitized assembly for accuracy in component alignment and ease of handling in manufacturing. 
     
     
         35 . The integrated cell assembly of  claim 34 , wherein the hot bond completely encapsulates the anode electrode and flow field within a hermetically sealed water region. 
     
     
         36 . The integrated cell assembly of  claim 35 , wherein the hot bonded seal is disposed between the sub-gasket of the membrane sub-gasket assembly and the water seal of the anode-gasket assembly. 
     
     
         37 . The integrated cell assembly of  claim 35 , wherein the materials for the at least one reinforcement border layer and water seal are selected from thermoplastic materials of compatible properties to allow homogeneous mixing at the interface during hot melt processing thereby eliminating a potential bond line between layers after processing. 
     
     
         38 . The electrolysis cell of  claim 1 , further comprising an electrically non-conductive sub-gasket surrounding the membrane, wherein each of the bipolar plate assembly, the anode or cathode flow field, and the sub-gasket comprise liquid plenum features that align when stacked, and wherein the liquid plenum features of the sub-gasket are dimensioned smaller than corresponding liquid plenum features of the bipolar plate assembly and anode or cathode flow field to create a non-conductive edge extension. 
     
     
         39 . The electrolysis cell of  claim 38 , wherein the non-conductive edge extension provides an electrical isolation path between electrically conductive components of adjacent cells in a stack that is greater than the thickness of the non-conductive sub-gasket. 
     
     
         40 . The electrolysis cell of  claim 39 , wherein the electrical isolation path is equal to the sum of the thickness of the non-conductive sub-gasket plus two times the length of the non-conductive edge extension. 
     
     
         41 . The electrolysis cell of  claim 1 , further comprising an electrically non-conductive sub-gasket surrounding the membrane, wherein each of the bipolar plate assembly, the anode or cathode flow field, and the sub-gasket comprise liquid plenum features that align when stacked; and
 an electrically non-conductive water seal having water plenum features that align with the liquid plenum features of the bipolar plate assembly, anode or cathode flow field, and sub-gasket when stacked.   
     
     
         42 . The electrolysis cell of  claim 41 , wherein the liquid plenum features of the water seal are dimensioned smaller than corresponding liquid plenum features of the bipolar plate assembly to provide electrical isolation for at least three edges of the liquid plenum. 
     
     
         43 . The electrolysis cell of  claim 42 , wherein a fourth edge of the liquid plenum is electrically isolated by a flap formed in the sub-gasket that wraps around the bipolar plate assembly to encapsulate the fourth edge with non-conductive material. 
     
     
         44 . The electrolysis cell of  claim 43 , wherein the flap has an overlap length sufficient to extend the electrical isolation path along the fourth edge to at least 1.5 times the cell pitch. 
     
     
         45 . A method of manufacturing an electrolysis cell with improved electrical isolation, comprising:
 providing an electrically conductive bipolar plate with water plenum features;   providing an electrically conductive flow field with water plenum features;   providing an electrically non-conductive sub-gasket with water plenum features dimensioned smaller than the corresponding water plenum features of the bipolar plate and flow field; and   laminating the bipolar plate, flow field, and sub-gasket such that their respective water plenum features align and create a non-conductive edge extension between conductive components and a water plenum.   
     
     
         46 . The method of  claim 45 , further comprising:
 providing an electrically non-conductive water seal with water plenum features dimensioned smaller than the corresponding water plenum features of the bipolar plate; and   laminating the water seal to provide electrical isolation for at least three edges of the water plenum.   
     
     
         47 . The method of  claim 46 , further comprising forming a flap in the sub-gasket and wrapping the flap around the bipolar plate to encapsulate a fourth edge of the water plenum with non-conductive material.