Provided is an LDH-like compound separator including a porous substrate made of a polymeric material; and a layered double hydroxide (LDH)-like compound with which pores of the porous substrate are plugged. A central region along the thickness of the LDH-like compound separator has a lower mean porosity than peripheral regions along the thickness of the LDH-like compound separator.

Provided is an LDH-like compound separator including a porous substrate made of a polymeric material; and a layered double hydroxide (LDH)-like compound with which pores of the porous substrate are plugged. A central region along the thickness of the LDH-like compound separator has a lower mean porosity than peripheral regions along the thickness of the LDH-like compound separator.

Provided is a layered double hydroxide (LDH) separator including a porous substrate made of a polymeric material; and a hydroxide-ion conductive layered compound being a LDH and/or a LDH-like compound with which pores of the porous substrate are plugged. The LDH separator has a mean porosity of 0.03% to less than 1.0%.

Provided is a layered double hydroxide (LDH) separator including a porous substrate made of a polymeric material; and a hydroxide-ion conductive layered compound being a LDH and/or a LDH-like compound with which pores of the porous substrate are plugged. The LDH separator has a mean porosity of 0.03% to less than 1.0%.

An anion exchange membrane includes a porous structural framework and bismuth atoms bonded to pore surfaces of the porous structural framework. Each bismuth atom is bonded to a pore surface by way of one or two oxygen atoms.

Aqueous electrolytes comprising fluorenone/fluorenol derivatives are disclosed. The electrolyte may be an anolyte for an aqueous redox flow battery. In some embodiments, the compound, or salt thereof, has a structure according to any one of formulas I-III ##STR00001##
where Q.sup.1-Q.sup.4 independently are CH, C(R.sup.1) or N, wherein 0, 1, or 2 of Q.sup.1-Q.sup.4 are N; Q.sup.5-Q.sup.8 independently are CH, C(R.sup.2), or N, wherein 0, 1, or 2 of Q.sup.5-Q.sup.8 are N; Y is C═O or C(H)OH; R.sup.1 and R.sup.2 independently are an electron withdrawing group; n is an integer >1; and x and y independently are 0, 1, 2, 3, or 4, where at least one of x and y is not 0.

Aqueous electrolytes comprising fluorenone/fluorenol derivatives are disclosed. The electrolyte may be an anolyte for an aqueous redox flow battery. In some embodiments, the compound, or salt thereof, has a structure according to any one of formulas I-III ##STR00001##
where Q.sup.1-Q.sup.4 independently are CH, C(R.sup.1) or N, wherein 0, 1, or 2 of Q.sup.1-Q.sup.4 are N; Q.sup.5-Q.sup.8 independently are CH, C(R.sup.2), or N, wherein 0, 1, or 2 of Q.sup.5-Q.sup.8 are N; Y is C═O or C(H)OH; R.sup.1 and R.sup.2 independently are an electron withdrawing group; n is an integer >1; and x and y independently are 0, 1, 2, 3, or 4, where at least one of x and y is not 0.

A fuel cell capable of reducing the stress exerted upon an electrolyte membrane resulting from the swelling and contraction of the electrolyte membrane. The fuel cell includes at least an MEGA with catalyst layers joined to the opposite sides of the electrolyte membrane, and a pair of separators disposed so as to sandwich the MEGA. The MEGA generates power with a hydrogen gas fed to one side of the MEGA and with an oxidant gas fed to the other side. Separators each have a plurality of projections formed on the side of the MEGA so as to form a gas channel through which the hydrogen gas or oxidant gas flows between the projections. The electrolyte membrane has a plurality of through-holes formed at positions facing the projections along the direction in which the projections extend.

Among the various aspects of the present disclosure is the provision of method of inducing or providing a pH gradient in electrochemical or chemical systems. Briefly, the pH gradient is induced by use of coated particles or films with an ion exchange ionomer.

Among the various aspects of the present disclosure is the provision of method of inducing or providing a pH gradient in electrochemical or chemical systems. Briefly, the pH gradient is induced by use of coated particles or films with an ion exchange ionomer.