Abstract: A fuel cell includes an anode including an anode catalyst, a cathode, a channel that is contiguous with the anode, and a liquid electrolyte in the channel. The cathode includes a gas diffusion electrode, a cathode catalyst on the gas diffusion electrode, and a hydrogel on the cathode catalyst. The hydrogel is between the anode and the cathode, and includes an aqueous liquid and a polymer. The polymer has an acid capacity less than 0.8 meq/g and/or has no sulfonic acid groups covalently bound to the polymer. A method of generating electricity includes flowing a liquid electrolyte through the channel, oxidizing a fuel at the anode, and reducing a gaseous oxidant at the cathode.

Abstract: An electrochemical cell includes an anode including an anode catalyst, a cathode including a cathode catalyst, and a first set of proton-conducting metal nanoparticles between the anode and the cathode, such that the first set of proton-conducting metal nanoparticles is not in contact with the anode. The cathode may be a cathode assembly including a gas diffusion electrode, a cathode catalyst on the gas diffusion electrode, and proton-conducting metal nanoparticles on the cathode catalyst.

Abstract: An electrochemical cell comprises a first electrode, a second electrode, a porous separator, between the first and second electrodes, a first channel, having an inlet and an outlet, and a second channel, having an inlet and an outlet. The first channel is contiguous with the first electrode and the porous separator, and the second channel is contiguous with the second electrode and the porous separator.

Abstract: An electrochemical cell includes an anode, a cathode including a gas diffusion electrode and having first and second surfaces, an inlet for gaseous oxidant that is in contact with the first surface of the cathode, and a liquid electrolyte. Water generated at the cathode may be transported by osmosis into the liquid electrolyte. The fuel cell may produce a current density of 200 mA/cm2 without cathode flooding.

Abstract: An electrochemical cell comprises a first electrode, a second electrode, a porous separator, between the first and second electrodes, a first channel, having an inlet and an outlet, and a second channel, having an inlet and an outlet. The first channel is contiguous with the first electrode and the porous separator, and the second channel is contiguous with the second electrode and the porous separator.

Abstract: A fuel cell is described. The fuel cell includes current collectors, each of which includes a substrate of lightweight material, such as Kapton material. Micro channels are formed via laser machining or chemical etching into the substrate. The current collectors further include conductive layers sputtered on the substrate, and protective coating on the conductive layers. A variety of materials are available for the conductive layers. The fuel cell so developed is particularly well suited to mobile applications, such as electronic devices.

Abstract: A fuel cell includes an anode including an anode catalyst, a cathode including a gas diffusion electrode and a cathode catalyst on the gas diffusion electrode, a channel that is contiguous with the anode, and a liquid including a fuel in the channel. The anode is in convective contact with the fuel, and the fuel cell has a fuel efficiency of at least 50%.

Abstract: A fuel cell includes an anode including an anode catalyst, a cathode, a channel that is contiguous with the anode, and a liquid electrolyte in the channel. The cathode includes a gas diffusion electrode, a cathode catalyst on the gas diffusion electrode, and a hydrogel on the cathode catalyst. The hydrogel is between the anode and the cathode, and includes an aqueous liquid and a polymer. The polymer has an acid capacity less than 0.8 meq/g and/or has no sulfonic acid groups covalently bound to the polymer. A method of generating electricity includes flowing a liquid electrolyte through the channel, oxidizing a fuel at the anode, and reducing a gaseous oxidant at the cathode.

Abstract: A fuel cell includes an anode, a cathode, a microfluidic channel contiguous with at least one of the anode and the cathode, and a single flowing electrolyte. The flowing electrolyte passes through the microfluidic channel. A method of generating electricity includes flowing the single electrolyte through the microfluidic channel, where a fuel is oxidized at the anode, an oxidant is reduced at the cathode, and the electrolyte comprises the fuel or the oxidant. The flowing electrolyte may pass through the microfluidic channel in a laminar flow.

Abstract: An electrochemical cell includes an anode including an anode catalyst, a cathode including a cathode catalyst, and a first set of proton-conducting metal nanoparticles between the anode and the cathode, such that the first set of proton-conducting metal nanoparticles is not in contact with the anode. The cathode may be a cathode assembly including a gas diffusion electrode, a cathode catalyst on the gas diffusion electrode, and proton-conducting metal nanoparticles on the cathode catalyst.

Abstract: An electrochemical cell includes an anode, a cathode including a gas diffusion electrode and having first and second surfaces, an inlet for gaseous oxidant that is in contact with the first surface of the cathode, and a liquid electrolyte. Water generated at the cathode may be transported by osmosis into the liquid electrolyte. The fuel cell may produce a current density of 200 mA/cm2 without cathode flooding.

Abstract: An electrochemical cell comprises a first electrode, a second electrode, a porous separator, between the first and second electrodes, a first channel, having an inlet and an outlet, and a second channel, having an inlet and an outlet. The first channel is contiguous with the first electrode and the porous separator, and the second channel is contiguous with the second electrode and the porous separator.

Abstract: A fuel cell is described. The fuel cell includes current collectors, each of which includes a substrate of lightweight material, such as Kapton material. Micro channels are formed via laser machining or chemical etching into the substrate. The current collectors further include conductive layers sputtered on the substrate, and protective coating on the conductive layers. A variety of materials are available for the conductive layers. The fuel cell so developed is particularly well suited to mobile applications, such as electronic devices.