US4761348A — Electrolytic cell stack with molten electrolyte m…

Claim 1

Independent Claim 341 words

In an electrolytic cell stack including a plurality of electrolytic cells with electrically conductive, electrolyte impermeable separator sheets between adjacent cells in said stack, the electrolytic cells including a porous anode member, a porous cathode member and a porous matrix for molten electrolyte disposed in the stack between major surfaces of the anode and cathode members, said stack having a negative end portion and a positive end portion at opposite ends thereof with the edge surfaces of the cells forming a first stack face for admitting a supply of oxidant gas and the edge surfaces forming a second stack face for admitting a supply of fuel gas, porous sealing means at the outer margins of the first stack face and at the outer margins of the second stack face for sealing to the supply of oxidant gas and to the supply of fuel gas, the improvement comprising: a first porous reservoir layer in the negative end portion of said stack having an edge surface thereof exposed to the supply of oxidant gas at the first stack face and being in electrolyte communication with the sealing means for receiving and containing electrolyte migrating towards the negative end of said stack, said first porous layer being separated from all adjacent electrodes and matrices by an electrolyte impermeable, electrically conducted layer; a second porous reservoir layer in the positive end portion of said stack having an edge surface exposed at the second stack face and being in electrolyte communication with the second sealing means for providing reserve electrolyte to fuel cells in the positive end portion of the stack, said second porous layer being separated from all adjacent electrodes and matrices by an electrolyte impermeable electrically conducted layer; and wherein said porous sealing means having a portion of increased cross-section and volume at the negative end portion of said stack and having a portion of its length of lesser volume and cross-section at the midportion of said stack for restricting molten electrolyte migration from the positive to the negative end portion of the stack.

Claim 2

Dependent Claim 341 words

In an electrolytic cell stack including a plurality of electrolytic cells with electrically conductive, electrolyte impermeable separator sheets between adjacent cells in said stack, the electrolytic cells including a porous anode member, a porous cathode member and a porous matrix for molten electrolyte disposed in the stack between major surfaces of the anode and cathode members, said stack having a negative end portion and a positive end portion at opposite ends thereof with the edge surfaces of the cells forming a first stack face for admitting a supply of oxidant gas and the edge surfaces forming a second stack face for admitting a supply of fuel gas, porous sealing means at the outer margins of the first stack face and at the outer margins of the second stack face for sealing to the supply of oxidant gas and to the supply of fuel gas, the improvement comprising: a first porous reservoir layer in the negative end portion of said stack having an edge surface thereof exposed to the supply of oxidant gas at the first stack face and being in electrolyte communication with the sealing means for receiving and containing electrolyte migrating towards the negative end of said stack, said first porous layer being separated from all adjacent electrodes and matrices by an electrolyte impermeable, electrically conducted layer; a second porous reservoir layer in the positive end portion of said stack having an edge surface exposed at the second stack face and being in electrolyte communication with the second sealing means for providing reserve electrolyte to fuel cells in the positive end portion of the stack, said second porous layer being separated from all adjacent electrodes and matrices by an electrolyte impermeable electrically conducted layer; and wherein said porous sealing means having a portion of increased cross-section and volume at the negative end portion of said stack and having a portion of its length of lesser volume and cross-section at the midportion of said stack for restricting molten electrolyte migration from the positive to the negative end portion of the stack.

Claim 3

Dependent Claim 37 words

The electrolytic cell stack of claim 1 wherein said porous sealing means at the midportion of said stack comprises a fiberous ceramic strip containing no more than about 4% by volume molten electrolyte to restrict electrolyte migration.

Claim 4

Dependent Claim 56 words

The electrolytic cell stack of claim 2 wherein said porous sealing means in the midportion of said stack comprises a fiberous ceramic strip having smooth fibers of about 5 to 20 microns diameter, a porosity of more than 90%, a width of about 1 to 2 cm and a thickness of about 0.1 to 0.2 cm.

Claim 5

Dependent Claim 33 words

The electrolytic cell stack of claim 3 wherein said porous sealing means is selected from the group of ceramics consisting of lithium aluminate, lithium zirconate, alumina, ceria, and calcia or yttria stabilized zirconia.

Claim 6

Dependent Claim 65 words

The electrolytic cell stack of claim 1 further comprising an additional porous reservoir layer of electrically conductive material at the negative end portion of said stack exposed to fuel gas at said second vertical face and separated from said first porous layer and adjacent electrodes and electrolyte matrices by at least one electrolyte impermeable, electrically conductive layer at a major surface of the reservoir layer.

Claim 7

Dependent Claim 26 words

The electrolytic cell stack of claim 5 wherein said additional porous layer is of compacted particles of nickel-chromium alloy having a porosity in excess of 50%.

Claim 8

Dependent Claim 29 words

The electrolytic cell stack of claim 1 wherein said first reservoir layer is of greater thickness than that of an individual anode member in the midportion of said stack.

Claim 9

Dependent Claim 140 words

An electrolytic cell stack with a plurality of cells from a positive to a negative end portion, the edge surfaces of said cells forming a first vertical face with sealing means for oxidant gas and a second vertical face with sealing means for fuel gas, said cell stack further comprising the combination of an electronically conductive, electrolyte reservoir in the negative end portion thereof, an electronically conductive, electrolyte reservoir in the positive end portion thereof and sealing means in the midportion thereof, said electrolyte reservoir comprising porous layers of electronically conductive material wettable by electrolyte and separated from adjacent electrodes and matrices by an electrolyte impermeable, electronically conductive layer, said sealing means extending between said reservoirs in the negative and positive stack end portions and being resistant to electrolyte migration between the positive and negative end portions of said stack.

Claim 10

Dependent Claim 140 words

An electrolytic cell stack with a plurality of cells from a positive to a negative end portion, the edge surfaces of said cells forming a first vertical face with sealing means for oxidant gas and a second vertical face with sealing means for fuel gas, said cell stack further comprising the combination of an electronically conductive, electrolyte reservoir in the negative end portion thereof, an electronically conductive, electrolyte reservoir in the positive end portion thereof and sealing means in the midportion thereof, said electrolyte reservoir comprising porous layers of electronically conductive material wettable by electrolyte and separated from adjacent electrodes and matrices by an electrolyte impermeable, electronically conductive layer, said sealing means extending between said reservoirs in the negative and positive stack end portions and being resistant to electrolyte migration between the positive and negative end portions of said stack.

Claim 11

Dependent Claim 38 words

The electrochemical cell stack of claim 8 wherein said electrolyte reservoir at the positive end portion of said stack is filled initially with substantially more electrolyte than the electrolyte reservoir at the negative end portion of said stack.

Claim 12

Dependent Claim 67 words

The electrolytic cell stack of claim 8 wherein said sealing means comprises a fiberous ceramic strip along marginal portions of a stack faces, said strip is of smooth fibers of about 5-20 microns diameter defining a porosity of more than 90%, a width of about 1-2 cm, a thickness of about 0.1 to 0.2 cm, to restrict electrolyte migration along the height of the electrolytic cell stack.

Claim 13

Dependent Claim 34 words

The electrolytic cell stack of claim 8 wherein cells in the positive end portion are filled with electrolyte to a substantially higher level than corresponding cells in the negative end portion of said stack.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1991-08-02	1992-02-01	1992-08-02	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1995-08-02	1996-02-01	1996-08-02	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1999-08-02	2000-02-01	2000-08-02	$7700.00	Window Closed / Lapsed

Electrolytic cell stack with molten electrolyte migration control

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