Techniques for improving fuel cells are presented herein. An electrochemical fuel cell, in accordance with an aspect of the present disclosure comprises bipolar plate layers comprising an anode plate and a cathode plate; a fuel supply to the anode plate; an oxidant supply to the cathode plate; gas diffusion layers proximate to a respective bipolar plate layer; an electrolyte membrane layer; a graphite honeycomb structure positioned between a gas diffusion layer and the electrolyte membrane layer; and a de-alloyed platinum with immobilized enzymes coupled to the graphite honeycomb structure.

Flow batteries can be constructed by combining multiple electrochemical unit cells together with one another in a cell stack. High-throughput processes for fabricating electrochemical unit cells can include providing materials from rolled sources for forming a soft goods assembly and a hard goods assembly, supplying the materials to a production line, and forming an electrochemical unit cell having a bipolar plate disposed on opposite sides of a separator. The electrochemical unit cells can have configurations such that bipolar plates are shared between adjacent electrochemical unit cells in a cell stack, or such that bipolar plates between adjacent electrochemical unit cells are abutted together with one another in a cell stack.

An electrochemical cell includes a pair of bipolar plates and a membrane electrode assembly between the bipolar plates. The membrane electrode assembly comprises an anode compartment, a cathode compartment, and a proton exchange membrane disposed therebetween. The cell further includes a sealing surface formed in one of the pair of bipolar plates and a gasket located between the sealing surface and the proton exchange membrane. The gasket is configured to plastically deform to create a seal about one of the cathode compartment or the anode compartment. The sealing surface can include one or more protrusions.

The invention proposes a method for connecting plate-like components of a bipolar plate, comprising the steps of placing a first plate-like component on a clamping surface, placing a second plate-like component onto the first plate-like component, fitting a plurality of hold-down devices on an outer surface of the second plate-like component, said outer surface facing away from the first plate-like component and the clamping surface, wherein an envisaged seam line is kept free between the hold-down devices, pressing of the plate-like components together using all of the hold-down devices, wherein, for this purpose, a magnetic force acting in the direction of the clamping surface is applied to at least one of the hold-down devices, and welding the plate-like components along the seam line in a continuous operation.

Systems and methods are provided for a redox flow battery. In one example, a method for the redox flow battery includes operating the redox flow battery in a short-term idle mode by discharging the redox flow battery at a constant current density over a duration of the short-term idle mode. By discharging the current density, a plated surface at a negative electrode of the redox flow battery may be maintained.

A layer system (1, 1′, 1″, Ia) for coating a bipolar plate (10) or an electrode unit (10a, 10b), including at least one first layer (2, 2a, 2b), at least one second layer (3), and at least one cover layer (4, 4a, 4b) arranged on the at least one second layer (3) made of a doped tetrahedral amorphic carbon ta-C:X, wherein as the dopant X, at least one element is provided from the group including titanium, niobium, tungsten, zirconium, tantalum, hafnium, molybdenum, copper, silicon, platinum, palladium, ruthenium, iridium, silver, boron, nitrogen, phosphor, fluorine, hydrogen, and oxygen, and the dopant X is provided in the cover layer (4, 4a, 4b) in a concentration of >0 to 20 at.-%. A bipolar plate (10) or an electrode unit (10a, 10b) having such a layer system and a fuel cell (100) and a redox flow cell (110) are also provided.

An integrated bipolar electrode includes a laminated structure and a bipolar plate. The laminated structure is formed by interconnecting an anode active material layer with a cathode active material layer. The bipolar plate is sandwiched in a hollow cavity of the laminated structure. Side surfaces of the laminated structure are provided with a sealing layer for mating with a bipolar electrode fixing frame to prevent an anolyte and a catholyte from permeating into each other. The anode active material layer and the cathode active material layer in the integrated bipolar electrode are directly connected. A contact resistance between the anode active material layer and the cathode active material layer is quite low, and a battery prepared finally has better performances.

A method for preparation of electrolyte for a redox flow battery includes reducing chromium ore using a carbon source to convert the chromium ore to an iron/chromium alloy with carbon particles; dissolving the iron/chromium alloy with carbon particles in sulfuric acid to form a first solution; adding calcium chloride or barium chloride to the first solution to produce a second solution including FeCl.sub.3 and CrCl.sub.3; and adding an acid to the second solution to form the electrolyte. Other methods can be used for preparing an electrolyte from chromium waste material.

A redox flow battery system includes an anolyte; a catholyte; a first electrode structure including a base having a first surface and a second surface opposite the first surface, a first electrode disposed on the first surface, a second electrode disposed on the second surface, and conductive elements that extend through the base, wherein the base resists flow of anolyte and catholyte through the base and each of the conductive elements includes a first end portion exposed at the first surface and a second end portion exposed at the second surface, wherein the first electrode includes the first end portions of the conductive elements and the second electrode includes the second end portions of the conductive elements; a first half-cell in which the first electrode is in contact with the anolyte; and a second half-cell in which the second electrode is in contact with the catholyte.

A redox flow battery system includes an anolyte having chromium ions in solution, wherein at least a portion of the chromium ions form a chromium complex with at least one of the following: NH.sub.3, NH.sub.4.sup.+, CO(NH.sub.2).sub.2, SCN.sup.−, or CS(NH.sub.2).sub.2; a catholyte having iron ions in solution; a first half-cell including a first electrode in contact with the anolyte; a second half-cell including a second electrode in contact with the catholyte; and a first separator separating the first half-cell from the second half-cell.