Provided is a gas diffusion layer, in which a microporous layer has an inner wall of through passages and a region adjacent to the through passages containing a greater amount of a water-repellent binder resin than a region not adjacent to the through passages, and thus water formed by an electrochemical reaction is effectively discharged from the gas diffusion layer. When the gas diffusion layer of the present invention is used, an optimal water management may be possible for smooth operation under all humidity conditions including a high humidity condition and a low humidity condition, and thus a fuel cell having improved cell performance may be obtained.

An apparatus for manufacturing a gas diffusion layer for fuel cells includes: a conveyer transferring a base sheet for a macroporous layer of the gas diffusion layer in one direction before water repellent coating; a nozzle disposed around the conveyer to coat the transferring base sheet with a water repellent in a fiber type or desired pattern; and a nozzle transfer unit combined with an upper end of the nozzle to transfer the nozzle along a desired trajectory.

A redox flow battery may include: a membrane interposed between a first electrode positioned at a first side of the membrane and a second electrode positioned at a second side of the membrane opposite to the first side; a first flow field plate comprising a plurality of positive flow field ribs, each of the plurality of positive flow field ribs contacting the first electrode at first supporting regions on the first side; and the second electrode, including an electrode spacer positioned between the membrane and a second flow field plate, the electrode spacer comprising a plurality of main ribs, each of the plurality of main ribs contacting the second flow field plate at second supporting regions on the second side, each of the second supporting regions aligned opposite to one of the plurality of first supporting regions. As such, a current density distribution at a plating surface may be reduced.

A redox flow battery may include: a membrane interposed between a first electrode positioned at a first side of the membrane and a second electrode positioned at a second side of the membrane opposite to the first side; a first flow field plate comprising a plurality of positive flow field ribs, each of the plurality of positive flow field ribs contacting the first electrode at first supporting regions on the first side; and the second electrode, including an electrode spacer positioned between the membrane and a second flow field plate, the electrode spacer comprising a plurality of main ribs, each of the plurality of main ribs contacting the second flow field plate at second supporting regions on the second side, each of the second supporting regions aligned opposite to one of the plurality of first supporting regions. As such, a current density distribution at a plating surface may be reduced.

An electrode for a redox flow battery through which an electrolyte is circulated includes a porous body, and reactive particles that contribute to a battery reaction. The reactive particles are pressed against the porous body by a flow of the electrolyte without being immobilized on the porous body.

Stable and high performance positive and negative electrolytes compositions to be used in redox flow battery systems are described. The redox flow battery system, comprises: at least one rechargeable cell comprising a positive electrolyte, a negative electrolyte, and an ionically conductive membrane positioned between the positive electrolyte and the negative electrolyte, the positive electrolyte in contact with a positive electrode, and the negative electrolyte in contact with a negative electrode. The positive electrolyte consists essentially of water, a first amino acid, an inorganic acid, an iron precursor, a supporting electrolyte, and optionally a boric acid. The negative electrolyte consists essentially of water, the iron precursor, the supporting electrolyte, and a negative electrolyte additive. The iron precursor is FeCl.sub.2, FeCl.sub.3, FeSO.sub.4, Fe.sub.2(SO.sub.4).sub.3, FeO, Fe, Fe.sub.2O.sub.3, or combinations thereof. The supporting electrolyte is LiCl, NaCl, Na.sub.2SO.sub.4, KCl, NH.sub.4Cl, or combinations thereof. The negative electrolyte additive is boric acid or a combination of the boric acid and a second amino acid.

A cation exchange membrane includes a film of fluorinated ionomer containing sulfonate groups. The film has a machine direction and a transverse direction perpendicular to the machine direction. The membrane has a water swell in both the machine direction and the transverse direction of less than about 5%. The membrane has a ratio of in-plane conductivity in the machine direction to in-plane conductivity in the transverse direction of about 0.9 to about 1.1. A process makes a cation exchange membrane including a film of fluorinated ionomer containing sulfonate groups. The process includes forming a film of the ionomer. The process also includes biaxially stretching the film in both a machine direction and a transverse direction perpendicular to the machine direction. An electrochemical cell has anode and cathode compartments and includes a cation exchange membrane as a separator between the anode and cathode compartments.

A fuel cell stack at least includes a stack body including a plurality of power generation cells each having a membrane electrode assembly stacked in a stacking direction, and a first dummy cell provided at one end of the stack body in the stacking direction. A dummy structural body of the first dummy cell is joined to a dummy resin frame member through an adhesive layer which adheres a first outer peripheral portion and a second outer peripheral portion, and inner periphery of the dummy resin frame member to each other.

A fuel cell stack at least includes a stack body including a plurality of power generation cells each having a membrane electrode assembly stacked in a stacking direction, and a first dummy cell provided at one end of the stack body in the stacking direction. A dummy structural body of the first dummy cell is joined to a dummy resin frame member through an adhesive layer which adheres a first outer peripheral portion and a second outer peripheral portion, and inner periphery of the dummy resin frame member to each other.

A method to produce a composite semi-finished product, having a continuous phase including at least one thermoplastic plastic and a dispersed phase made from at least one electrically conductive filler. The at least one thermoplastic plastic in form of fine particles is mixed with the at least one filler in the form of fine particles. In each case, at least 90% by weight of the particles of the at least one thermoplastic plastic and of the at least one filler are smaller than 1 mm. The mixture of the at least one thermoplastic plastic and the at least one filler is heated to a temperature greater than the melting temperature of the at least one thermoplastic plastic. The heated material is cooled to a temperature below the solidification temperature of the at least one thermoplastic plastic.