US-12620605-B2 - Power connection for electrochemical cell stack

US12620605B2US 12620605 B2US12620605 B2US 12620605B2US-12620605-B2

Abstract

An electrochemical cell assembly ( 300, 500 ) comprising a base plate ( 308 ) and a top plate ( 303 ) between which a stack of planar cell units ( 306 ) and at least one positive ( 302, 507 ) and at least one negative electrical end plate ( 302, 507 ) are disposed in compression by means of compression means ( 307 ) acting between the base plate ( 308 ) and top plate ( 303 ). At least one of the electrical end plates ( 302, 507 ) is connected or integrally formed with, and in electrical contact with, an electrical stud ( 301, 505 ) that extends from a base portion of the at least one electrical end plate ( 302, 507 ) and passes through an opening in one of the base plate ( 308 ) and top plate ( 303 ) to form an electrical terminal. A fluidic seal is maintained by the compression means ( 307 ) between the base portion and the respective one of the base plate ( 308 ) and top plate ( 303 ), so as to prevent loss of fluid through the opening.

Inventors

Tomasz DOMANSKI
Matthew Harrington

Assignees

CERES INTELLECTUAL PROPERTY COMPANY LIMITED

Dates

Publication Date: 20260505
Application Date: 20210812
Priority Date: 20200826

Claims (15)

1 . An electrochemical cell assembly comprising: a base plate and a top plate between which a stack of planar cell units and a plurality of electrical end plates are disposed in compression by means of compression means acting between the base plate and top plate, wherein the plurality of electrical end plates comprise at least one positive electrical end plate and at least one negative electrical end plate; wherein at least one of the plurality of electrical end plates is connected or integrally formed with, and in electrical contact with, a respective electrical stud of corresponding polarity that extends from a base portion of the at least one of the plurality of electrical end plates and passes through an opening in one of the base plate and top plate to form an electrical terminal; wherein a fluidic seal is maintained by the compression means between the base portion and the respective one of the base plate and top plate, so as to prevent loss of fluid through the opening; and, wherein cell units in the stack of planar cell units are provided with at least one port and are stacked one upon another such that the respective ports align to form a respective internal manifold extending through the stack, and wherein the electrical stud extending through its respective opening is also in alignment with the respective internal manifold, such that the compression forces exerted by the compression means to seal the respective internal manifold also act to seal the respective opening.
2 . The electrochemical cell assembly according to claim 1 , wherein each of the base plate and top plate is respectively electrically insulated from the stack of planar cell units by means of an insulating layer provided between the respective end of the stack of planar cell units and the respective base plate and top plate.
3 . An electrochemical cell assembly according to claim 1 , wherein the plurality of electrical end plates comprises: at least one positive electrical end plate that is connected or integrally formed with, and in electrical contact with, a positive electrical stud that extends from a base portion thereof and passes through a first opening in one of the base plate and top plate to form a positive electrical terminal; and, at least one negative electrical end plate that is connected or integrally formed with, and in electrical contact with, a negative electrical stud that extends from a base portion thereof and passes through a second opening in one of the base plate and top plate to form a negative electrical terminal; wherein the fluidic seal is maintained by the compression means between each base portion and the respective one of the base plate and top plate, so as to prevent loss of fluid through each respective opening.
4 . The electrochemical cell assembly according to claim 3 , wherein the positive electrical stud passes through the first opening in one of the top plate and the base plate and the negative electrical stud passes through the second opening, wherein the second opening is in the other of the top plate and the base plate.
5 . The electrochemical cell assembly according to claim 3 , wherein the positive electrical stud and the negative electrical stud both pass through their respective first and second openings in either the base plate or the top plate.
6 . The electrochemical cell assembly according to claim 5 , wherein one of the positive and negative electrical studs is electrically connected to an additional electrical end plate of the same polarity as that stud by a busbar, and optionally, wherein the connection to the busbar is via at least one tab that is more flexible than the busbar and the connected electrical end plates.
7 . The electrochemical cell assembly according to claim 3 , wherein the assembly comprises: first and second respective internal manifolds extending through the stack; wherein the negative electrical stud is aligned with the first respective internal manifold; and, wherein the positive electrical stud is aligned with the second respective internal manifold.
8 . The electrochemical cell assembly according to claim 7 , wherein the negative and positive electrical studs both pass through their respective openings in either the base plate or the top plate, and one of the negative and positive electrical studs is electrically connected to an additional electrical end plate by a busbar.
9 . The electrochemical cell assembly according to claim 8 , wherein a first fluid volume comprising the first and second internal manifolds is supplied and exhausted by respective fluid inlet and outlet openings in the other of the base plate and top plate.
10 . The electrochemical cell assembly according to claim 7 , wherein the negative and positive electrical studs both pass through their respective openings in either the base plate or the top plate, and one of the negative and positive electrical studs also passes through an opening provided in the electrical end plate that is connected or integrally formed with, and in electrical contact with, the other one of the negative and positive electrical studs.
11 . The electrochemical cell assembly according to claim 1 , wherein the base portion of the respective electrical end plate extends across the respective internal manifold to block it.
12 . The electrochemical cell assembly according to claim 1 , wherein at least one of the positive and negative electrical end plates separates a first fluid volume and a second fluid volume within the stack.
13 . The electrochemical cell assembly according to claim 1 , wherein the compression means comprises a skirt attached in tension between the base plate and the top plate, which skirt encloses at least the stack of planar cell units.
14 . The assembly according to claim 1 , wherein the planar cell units comprise solid oxide, fuel cell or electrolyser cell units.
15 . An electrochemical cell assembly comprising: a base plate and a top plate between which a stack of planar cell units and a plurality of electrical end plates are disposed in compression by means of compression means acting between the base plate and top plate, wherein the plurality of electrical end plates comprise at least one positive electrical end plate and at least one negative electrical end plate, wherein: at least one of the plurality of electrical end plates is connected or integrally formed with, and in electrical contact with, a respective electrical stud of corresponding polarity extending from a stud base portion, the electrical stud passes through an opening in one of the base plate and top plate to form an electrical terminal, each of the cell units is provided with at least one port and the cell units are stacked one upon another such that the respective ports align to form a respective internal manifold extending through the stack, and, the electrical stud extending through the respective opening is also in alignment with the respective internal manifold, such that the compression forces exerted by the compression means to seal the respective internal manifold also act to seal the opening.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a national stage entry of International Patent Application No. PCT/EP2021/072526, filed 12 Aug. 2021, entitled “POWER CONNECTION FOR ELECTROCHEMICAL CELL STACK,” which claims priority to Great Britain Patent Application Nos. 2013369.0, filed on 26 Aug. 2020, and 2013374.0, filed on 26 Aug. 2020, the disclosures of which are hereby incorporated by reference in their entirety. FIELD OF THE INVENTION The present invention relates to electrochemical cell stacks, in particular, fuel cell stacks and electrolyser cell stacks, and to the design of their electrical end plates. The cell stacks of the present invention include cells of solid oxide, polymer electrolyte membrane, and molten carbonate types. The present invention more specifically relates to solid oxide fuel cell (SOFC) and solid oxide electrolyser cell (SOEC) stacks, and these may include metal-supported solid oxide fuel cell (MS-SOFC) or electrolyser cell stacks (MS-SOEC). BACKGROUND TO THE INVENTION Some fuel cell units can produce electricity by using an electrochemical conversion process that oxidises fuel to produce electricity. Some fuel cell units can also, or instead, operate as regenerative fuel cells (or reverse fuel cells) units, often known as electrolyser fuel cell units, for example to separate hydrogen and oxygen from water, or carbon monoxide and oxygen from carbon dioxide. They may be tubular or planar in configuration. Planar fuel cell units may be arranged overlying one another in a stack arrangement, for example 100-200 fuel cell units in a stack, with the individual fuel cell units arranged electrically in series. A solid oxide fuel cell (SOFC) that produces electricity is based upon a solid oxide electrolyte that conducts negative oxygen ions from a cathode to an anode located on opposite sides of the electrolyte. For this, a fuel, or reformed fuel, contacts the anode (fuel electrode) and an oxidant, such as air or an oxygen rich fluid, contacts the cathode (air electrode). Conventional ceramic-supported (e.g. anode-supported) SOFCs have low mechanical strength and are vulnerable to fracture. Hence, metal-supported SOFCs have recently been developed which have the active fuel cell component layer supported on a metal substrate. In these cells, the ceramic layers can be very thin since they only perform an electrochemical function: that is to say, the ceramic layers are not self-supporting but rather are thin coatings/films laid down on and supported by the metal substrate. Such metal supported SOFC stacks are more robust, lower cost, have better thermal properties than ceramic-supported SOFCs and can be manufactured using conventional metal welding techniques. A solid oxide electrolyser cell (SOEC) may have the same structure as an SOFC but is essentially that SOFC operating in reverse, or in a regenerative mode, to achieve the electrolysis of water and/or carbon dioxide by input of electrical energy and using the solid oxide electrolyte to produce hydrogen gas and/or carbon monoxide and oxygen. The present invention is directed at a stack of repeating electrochemical cell units and concerns the design of their electrical end plates (power take-off or delivery). It is thus applicable to various types of fuel and electrolyser cells, for example, based on solid oxide electrolytes, polymer electrolyte membranes, or molten electrolytes. For convenience, “cell units” is used to refer to “electrochemical cell units” including fuel or electrolyser cell units. The electrical energy produced by a fuel cell (or input to an electrolyser cell) may be transferred through a stack of cell units and transferred from (or to) the stack using two electrical studs (of opposite electrical polarity) and associated electrical end plates which make electrical contact between the studs and the ends of the stack. The electrical studs and electrical end plates may also be referred to as positive and negative “power take offs”, which terminology is used for convenience regardless of whether the power is being taken off (as in case of fuel cell) or delivered (as in case of electrolyser cell). The stack is typically enclosed in a vessel to form a fluid volume and thereby to retain one of the fluids (fuel or air and/or exhaust gasses) for use in—or exhaust from—the stack. The electrical studs typically pass through the vessel in order to allow electrical energy to be transferred between the stack and a load or source external to the stack (the electrical stud, or bolt, passed through an opening in the vessel for external connection, the (distal) portion of the stud external to the vessel may form a terminal). A fluid seal is typically required to be maintained between the power take offs and the vessel in order to maintain the integrity of the fluid volume enclosed by the vessel. Operating a fuel cell (for example an SOFC) system where the cell stack operates in the 450-650 Deg C. range (for example, in