A cell including: a body having a first end portion and a second end portion; a first electrode layer electrically connected to the body; a solid electrolyte layer located on the first electrode layer; and a second electrode layer located on the solid electrolyte layer, wherein the body includes a flared gas-flow passage passing through the body from the first end portion to second end portion; and diameters of opposing end portions of the flared gas-flow passage are greater than a diameter of the flared gas-flow passage at a central portion between the opposing end portions.

The purpose of the present invention is to provide: a method for producing a gas diffusion electrode base which enables the achievement of a gas diffusion electrode base that has a microporous layer with small surface roughness and is not susceptible to damaging an electrolyte membrane; and a gas diffusion electrode base that has a microporous layer with small surface roughness and is not susceptible to damaging an electrolyte membrane. For the purpose of achieving the above-described purpose, the present invention has the configuration described below. Namely, a specific gas diffusion electrode base which has a carbon sheet and a microporous layer, and wherein the carbon sheet is porous and the DBP oil absorption of a carbon powder contained in the microporous layer is 70-155 ml/100 g.

The purpose of the present invention is to provide: a method for producing a gas diffusion electrode base which enables the achievement of a gas diffusion electrode base that has a microporous layer with small surface roughness and is not susceptible to damaging an electrolyte membrane; and a gas diffusion electrode base that has a microporous layer with small surface roughness and is not susceptible to damaging an electrolyte membrane. For the purpose of achieving the above-described purpose, the present invention has the configuration described below. Namely, a specific gas diffusion electrode base which has a carbon sheet and a microporous layer, and wherein the carbon sheet is porous and the DBP oil absorption of a carbon powder contained in the microporous layer is 70-155 ml/100 g.

A layered film is prepared by layering a substrate layer, a first layer containing an acid-modified olefin-based resin, a second layer containing a cyclic olefin-based resin, and an ion-exchange resin-containing layer containing an ion-exchange resin in this order. Each of the second layer and the first layer may be a layer formed by coating. The average thickness of the second layer may be 30 μm or less. A membrane electrode assembly of a solid polymer-type fuel battery may be produced by releasing a layer other than the ion-exchange resin-containing layer from the layered film. The layered film does not contain a component having a large environmental load even when the release layer is formed of the cyclic olefin-based resin, firmly attaches to a substrate, and can be released smoothly from the ion-exchange resin-containing layer serving as a transfer medium.

A method for producing a compound represented by formula (P1): (B.sup.1f).sub.mp(A.sup.1).sub.np, wherein B.sup.1f is RfCOO, Rf is a hydrocarbon having one or more fluorine atoms, A.sup.1 is a group excluding H, mp is (valence of A.sup.1)×np and is 1 or 2, np is mp/(valence of A.sup.1) and is 1, A.sup.1 has a valence of 1 or 2, the method comprising step A of reacting a compound represented by formula (S1): (B.sup.1f)(R.sup.1), wherein B.sup.1f is as defined above, and R.sup.1 is an organic group, and a compound represented by formula (S2): (A.sup.1).sub.ms2(B.sup.2).sub.ns2, wherein A.sup.1 is as defined above, B.sup.2 is OH, CO.sub.3, or HCO.sub.3, ms2 is (valence of B.sup.2)×ns2/(valence of A.sup.1) and is 1 or 2, and ns2 is (valence of A.sup.1)×ms2/(valence of B.sup.2) and 1 or 2, or a hydrate thereof.

Such a method is a novel production method of a fluorinated carboxylic acid salt compound (preferably a fluorinated carboxylic acid salt compound having a low water content).

In order to provide a method for producing a composite of a bipolar plate and an MEA, the following is proposed: arranging the bipolar plate in a tool, which has a ferromagnetic or magnetic element, which partially forms the contact surface for the bipolar plate and is designed to be removable from the tool, arranging a membrane electrode assembly on the bipolar plate, arranging a second ferromagnetic or magnetic element on the membrane electrode assembly, removing the membrane electrode assembly and bipolar plate fixed to one another by the two ferromagnetic or magnetic elements, inserting the bipolar plate fixed to the membrane electrode assembly into a second tool, injecting a melt of a polymeric sealing material into the at least one mold cavity of the tool, allowing the melt to solidify, and demolding and removing the composite or the composites. In addition, a composite and a fuel cell stack are disclosed.

A cell includes an element portion, a gas-flow passage, a first metal portion, a second metal portion, and a reinforcing portion. Reaction gas flows through the gas-flow passage. The first metal portion is located between one surface side of the gas-flow passage and the element portion, and supports the element portion. The second metal portion is located on the other surface side opposite to the one surface side of the gas-flow passage. The reinforcing portion is located inside the gas-flow passage and faces the first metal portion and the second metal portion.

Realized is an element having an electrolyte layer that is dense and has high gas barrier characteristics. A metal-supported electrochemical element includes at least a metal substrate as a support, an electrode layer formed on/over the metal substrate, a buffer layer formed on the electrode layer, and an electrolyte layer formed on the buffer layer. The electrode layer is porous and the electrolyte layer is dense. The buffer layer has density higher than density of the electrode layer and lower than density of the electrolyte layer.

Realized is an element having an electrolyte layer that is dense and has high gas barrier characteristics. A metal-supported electrochemical element includes at least a metal substrate as a support, an electrode layer formed on/over the metal substrate, a buffer layer formed on the electrode layer, and an electrolyte layer formed on the buffer layer. The electrode layer is porous and the electrolyte layer is dense. The buffer layer has density higher than density of the electrode layer and lower than density of the electrolyte layer.

An electrochemical cell includes a fuel electrode, an air electrode containing a perovskite type oxide as a main component, the perovskite type oxide being represented by a general formula ABO.sub.3 and containing La and Sr at the A site, and a solid electrolyte layer arranged between the fuel electrode and the air electrode. The air electrode includes a first portion and a second portion, the first portion being located on the most upstream side in a flow direction of an oxidant gas that flows through a surface of the air electrode, the second portion being located on the most downstream side in the flow direction. A first ratio of a La concentration to a Sr concentration detected at the first portion through Auger electron spectroscopy is at least 1.1 times a second ratio of a La concentration to a Sr concentration detected at the second portion through Auger electron spectroscopy.