Provided are composite electrolytes having a bio-based gel electrolyte in an ordered structure of a porous solid. In some embodiments, the gel electrolyte includes a glycolate gel, a glycerate gel, a bio-based compound-derived gel or a combination thereof. Also provided are electrochemical systems (electrodeposition), redox flow batteries, fuel cells, lithium-ion batteries and lithium-metal batteries including the composite electrolytes, and methods for producing gel electrolytes. In some embodiments, the methods including reacting a polyol, optionally ethylene glycol, propanediol, butanediol, pentanediol, diethylene glycol, glycerol, or any combination thereof, with a lithium metal and/or a lithium salt, optionally lithium hydroxide, a sodium salt, optionally sodium hydroxide (NaOH), NaTFSI, NaBF.sub.4, or NaPF.sub.6; an aluminum salt; a potassium salt, a magnesium salt; a calcium salt; a zinc salt; or any combination thereof.

In an embodiment, a fuel cell includes: a flexible substrate including a first fuel-tolerant material; a fitting on the flexible substrate, the fitting including first openings extending through an outer portion of the fitting; a primer coating on the outer portion of the fitting, the primer coating including a second fuel-tolerant material; first yarns strung through the first openings of the fitting, the first yarns stitched into the flexible substrate; and an encapsulant encapsulating the first yarns, the primer coating, and the outer portion of the fitting, the encapsulant disposed on the flexible substrate, the encapsulant including a third fuel-tolerant material, the third fuel-tolerant material chemically bonded to the second fuel-tolerant material and the first fuel-tolerant material.

A composite polymer electrolyte membrane comprising a nanofiber sheet having a basis weight of 1.5 g/m.sup.2 or more and 4.0 g/m.sup.2 or less, and a proton-conducting polymer, the electrolyte membrane having a sheet shape in which the proton-conducting polymer and the nanofiber sheet are combined, and having an average coefficient of linear expansion of 300 ppm/K or less from 20° C. to 120° C. in an in-plane direction of the sheet shape.

A composite polymer electrolyte membrane comprising a nanofiber sheet having a basis weight of 1.5 g/m.sup.2 or more and 4.0 g/m.sup.2 or less, and a proton-conducting polymer, the electrolyte membrane having a sheet shape in which the proton-conducting polymer and the nanofiber sheet are combined, and having an average coefficient of linear expansion of 300 ppm/K or less from 20° C. to 120° C. in an in-plane direction of the sheet shape.

An electrolyte membrane is described that has improved bondability with a catalyst layer and that achieves good power generation performance, without the electrolyte membrane undergoing a physical treatment and without any loss of surface modification effect, where the electrolyte membrane comprises a polymer electrolyte and a nonionic fluorochemical surfactant.

An electrolyte membrane is described that has improved bondability with a catalyst layer and that achieves good power generation performance, without the electrolyte membrane undergoing a physical treatment and without any loss of surface modification effect, where the electrolyte membrane comprises a polymer electrolyte and a nonionic fluorochemical surfactant.

A polymer electrolyte membrane includes an ion-conducting polymeric electrolyte material and platelets, distributed through the polymeric electrolyte material. The platelets have an aspect ratio of length to thickness of at least 2:1. The platelets are aligned generally parallel to a length of the membrane. The platelets can be functionalized with free radical scavengers, or other moieties, to extend the lifetime of the membrane or of a membrane electrode assembly incorporating the membrane.

A polymer electrolyte membrane includes an ion-conducting polymeric electrolyte material and platelets, distributed through the polymeric electrolyte material. The platelets have an aspect ratio of length to thickness of at least 2:1. The platelets are aligned generally parallel to a length of the membrane. The platelets can be functionalized with free radical scavengers, or other moieties, to extend the lifetime of the membrane or of a membrane electrode assembly incorporating the membrane.

Systems, methods, and membranes involving ion exchange membranes are disclosed. In an embodiment of the present invention, an ultrathin laminar layer made of inorganic nanosheets may be coated on one side or both sides of a polymeric anion exchange membrane (AEM), forming a composite AEM. Oxidation stability measurements may indicate that composite AEM provide superior oxidation resistance to exemplary polymeric AEMs and to commercial polymeric AEMs.

A boron-containing proton-exchange solid support may include a proton-exchange solid support comprising an oxygen atom and a tetravalent boron-based acid group comprising a boron atom covalently bonded to the oxygen atom.