Physicochemical properties of Aquivion/fluorine grafted sepiolite electrolyte membranes for use in PEMFC

Abstract

This study proposes a novel sepiolite-based Aquivion electrolyte membrane which could be operated at low relative humidity. In the study, it was discovered that the functionalization of sepiolite with fluorinated groups (i.e.,-C 7 F 15), named SEP-F, helps its dispersion in the composite membrane, compared with the use of natural sepiolite. The Aquivion/SEP-F composite membrane showed increased water uptake, thermo-mechanical and chemical stability as well as proton conductivity and decreased swelling compared with commercially available Nafion HP and pristine Aquivion. Their behavior in single cell MEA testing conditions was also assessed. Aquivion/SEP-F composite membrane can be an interesting alternative for low relative humidity operation of PEMFC (proton exchange membrane fuel cell).

Incorporating sepiolite and kaolinite to improve the performance of SPEEK composite membranes for proton exchange membrane fuel cells

“…According to Figure , the SPEEK membrane has uniform morphology and the image can be confirmed by other studies . The surface of the 15% sepiolite‐added SPEEK membrane (Figure B) cross‐section is smooth, without the segregation of clay particles from the polymer matrix, thereby demonstrating a adequate compatibility between the sepiolite and SPEEK . The hydrophilic kaolinite particles are dispersed into the polymer matrix and are clearly visible in Figure C.…”

“…Therefore, their high surface area and exceptional hydrophilic modifiable properties make them useful as additives for PEMFC applications . There are only a few studies in which clays or zeolites are used as additives for proton exchange membranes . Sepiolite, despite its phyllosilicate structure (57% SiO 2 , 8.50% Al 2 O 3 , 13.10% MgO), is particularly interesting due to its fibrous morphology (needle‐like structure), nontoxicity, and high surface area.…”

“…The micropore and mesopore size of the sepiolite is 1.5 and 4.5 nm. Additionally, sepiolite chains can be linked to viscoelastic materials (chain packing effect), leading to the enhanced mechanical stability of the polymer . Kaolinite is another non‐metallic mineral clay that can enhance the thermal strength of the SPEEK membrane since the thermal decomposition of kaolinite begins after 800°C.…”

“…[36] There are only a few studies in which clays or zeolites are used as additives for proton exchange membranes. [37][38][39] Sepiolite, despite its phyllosilicate structure (57% SiO 2 , 8.50% Al 2 O 3 , 13.10% MgO), is particularly interesting due to its fibrous morphology (needle-like structure), nontoxicity, and high surface area. The structure of sepiolite has parallel tunnels shaped by blocks.…”

“…Additionally, sepiolite chains can be linked to viscoelastic materials (chain packing effect), leading to the enhanced mechanical stability of the polymer. [39] Kaolinite is another nonmetallic mineral clay that can enhance the thermal strength of the SPEEK membrane since the thermal decomposition of kaolinite begins after 800 C. It has high-impact strength and resistance to chemical activity. [38] This clay is commonly used as filler in materials such as ceramics, bricks, and plastics for industrial and pharmaceutical operations.…”