Enhanced proton conductivity of sulfonated poly(ether ether ketone) membranes at elevated temperature by incorporating (3-aminopropyl)triethoxysilane-grafted graphene oxide

Rational Materials and Structure Design for Improving the Performance and Durability of High Temperature Proton Exchange Membranes (HT-PEMs)

Hydrogen energy as the next-generation clean energy carrier has attracted the attention of both academic and industrial fields. A key limit in the current stage is the operation temperature of hydrogen fuel cells, which lies in the slow development of high-temperature and high-efficiency proton exchange membranes. Currently, much research effort has been devoted to this field, and very innovative material systems have been developed. The authors think it is the right time to make a short summary of the high-temperature proton exchange membranes (HT-PEMs), the fundamentals, and developments, which can help the researchers to clearly and efficiently gain the key information. In this paper, the development of key materials and optimization strategies, the degradation mechanism and possible solutions, and the most common morphology characterization techniques as well as correlations between morphology and overall properties have been systematically summarized.

Preparation and performance of sulfonated poly(ether ether ketone) membranes enhanced with ammonium ionic liquid and graphene oxide

The exploration of proton exchange membranes with excellent performance has always been under focus for improving the performance of proton exchange membrane fuel cells. In this study, novel ternary composite proton exchange membranes based on sulfonated poly(ether ether ketone) (SPEEK), triethylamine phosphate (TEAP) as the ammonium ionic liquid (AIL), and graphene oxide (GO) were prepared. The prepared membranes were characterized for their physical, physico-chemical, structural, morphological, thermal, mechanical, and electrical characteristics. The thermal stability of the SPEEK membrane was improved by the addition of GO and TEAP. GO was inserted into the composite membrane to form proton transfer channels. The amine ions in AIL formed acid–base pairs with the sulfonic acid group, whereas the oxygen-containing group on GO formed hydrogen bonds with the phosphate group. These groups interacted with each other to form a honeycomb-like structure, which anchored the AIL in the membrane and reduced its loss, providing additional sites for proton transport at higher temperatures. The proton conductivity of the SPEEK/AIL/GO-2 membrane reached 17.345 mS/cm at 120°C, which was 2.09 times higher than that of the pristine SPEEK membrane. This study provides the possibility for better preparation of proton exchange membranes used for high-temperature proton exchange membrane fuel cells.

Transport Properties and Mechanical Features of Sulfonated Polyether Ether Ketone/Organosilica Layered Materials Nanocomposite Membranes for Fuel Cell Applications

In this work, we study the preparation of new sulfonated polyether ether ketone (sPEEK) nanocomposite membranes, containing highly ionic silica layered nanoadditives, as a low cost and efficient proton exchange membranes for fuel cell applications. To achieve the best compromise among mechanical strength, dimensional stability and proton conductivity, sPEEK polymers with different sulfonation degree (DS) were examined. Silica nanoplatelets, decorated with a plethora of sulfonic acid groups, were synthesized through the one-step process, and composite membranes at 1, 3 and 5 wt% of filler loadings were prepared by a simple casting procedure. The presence of ionic layered additives improves the mechanical strength, the water retention capacity and the transport properties remarkably. The nanocomposite membrane with 5% wt of nanoadditive exhibited an improvement of tensile strength almost 160% (68.32 MPa,) with respect to pristine sPEEK and a ten-times higher rate of proton conductivity (12.8 mS cm⁻¹) under very harsh operative conditions (i.e., 90 °C and 30% RH), compared to a filler-free membrane. These findings represent a significant advance as a polymer electrolyte or a fuel cell application.

Process Optimization of Via Plug Multilevel Interconnections in CMOS Logic Devices

This paper reports on the optimization of the device and wiring in a via structure applied to multilevel metallization (MLM) used in CMOS logic devices. A MLM via can be applied to the Tungsten (W) plug process of the logic device by following the most optimized barrier deposition scheme of RF etching 200 Å IMP Ti (ion metal plasma titanium) 200 Å CVD TiN (titanium nitride deposited by chemical vapor deposition) 2 × 50 Å. The resistivities of the glue layer and barrier, i.e., IMP Ti and CVD TiN, were 73 and 280 μΩ·cm, respectively, and the bottom coverages were 57% and 80%, respectively, at a 3.2:1 aspect ratio (A/R). The specific resistance of the tungsten film was approximately 11.5 μΩ·cm, and it was confirmed that the via filling could be performed smoothly. RF etching and IMP Ti should be at least 200 Å each, and CVD TiN can be performed satisfactorily with the existing 2 × 50 Å process. Tungsten deposition showed no difference in the via resistance with deposition temperature and SiH4 reduction time. When the barrier scheme of RF etching 200 Å IMP Ti 200 ÅCVD TiN 2 × 50 Å was applied, the via resistance was less than 20 Ω, even with a side misalignment of 0.05 μm and line-end misalignment of ~0.1 μm.