Sulfonated Polyimide Membranes Derived from a Novel Sulfonated Diamine with Pendant Benzenesulfonic Acid for Fuel Cells

For improving the hydrolytic stability of sulfonated polyimides consisting of five membered anhydrides, novel sulfonated polyimides (NSPIs) were prepared via polymerization of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), with a novel diamine monomer with a pendant sulfonic acid group and 4,4-oxydianiline. Water uptake of this NSPI with an excellent film-forming ability was almost equal to that of Nafion® 117, while their ion exchange capacity (IEC) was 22% higher than Nafion® 117. The loss in weight decreased by 53% and loss in IEC decreased by 66% compared to that of Nafion® 117; both were used to quantitatively measure hydrolytic stability, and radical oxidative stability also increased by 75% when compared with Nafion® 117. Mechanically, this NSPI was superior, and its proton conductivity was higher than Nafion® 117 at elevated temperatures. All these improvements were due to the introduction of this pendant group. Taken together, we herein report a promising renewable energy source based on SPIs capable of displaying proton conductivity and enhanced hydrophilicity.

A Patternable and In Situ Formed Polymeric Zinc Blanket for a Reversible Zinc Anode in a Skin-Mountable Microbattery

Owing to their high safety and reversibility, aqueous microbatteries using zinc anodes and an acid electrolyte have emerged as promising candidates for wearable electronics. However, a critical limitation that prevents implementing zinc chemistry at the microscale lies in its spontaneous corrosion in an acidic electrolyte that causes a capacity loss of 40% after a ten-hour rest. Widespread anti-corrosion techniques, such as polymer coating, often retard the kinetics of zinc plating/stripping and lack spatial control at the microscale. Here, a polyimide coating that resolves this dilemma is reported. The coating prevents corrosion and hence reduces the capacity loss of a standby microbattery to 10%. The coordination of carbonyl oxygen in the polyimide with zinc ions builds up over cycling, creating a zinc blanket that minimizes the concentration gradient through the electrode/electrolyte interface and thus allows for fast kinetics and low plating/stripping overpotential. The polyimide's patternable feature energizes microbatteries in both aqueous and hydrogel electrolytes, delivering a supercapacitor-level rate performance and 400 stable cycles in the hydrogel electrolyte. Moreover, the microbattery is able to be attached to human skin and offers strong resistance to deformations, splashing, and external shock. The skin-mountable microbattery demonstrates an excellent combination of anti-corrosion, reversibility, and durability in wearables.

Preparation of sulfonic acid functional proton conducting phosphazenes by covalent protection

An easy and efficient method has been developed for preparation of sulfonic acid functional cyclic and polymeric phosphazenes by selective covalent protection of the sulfonic acid moiety.

Organic–inorganic polyimides with double decker silsesquioxane in the main chains

In this contribution, we report the synthesis of organic–inorganic polyimides with double decker silsesquioxane in the main chains with a novel and well-defined POSS diamine.

Fuel cell electrocatalyst using polybenzimidazole-modified carbon nanotubes as support materials

Toward the next generation fuel cell systems, the development of a novel electrocatalyst for the polymer electrolyte fuel cell (PEFC) is crucial to overcome the drawbacks of the present electrocatalyst. As a conductive supporting material for the catalyst, carbon nanotubes (CNTs) have emerged as a promising candidate, and many attempts have been carried out to introduce CNT, in place of carbon black. On the other hand, as a polymer electrolyte, polybenzimidazoles (PBIs) have been recognized as a powerful candidate due to the high proton conductivity above 100 °C under non-humid conditions. In 2008, we found that these two materials have a strong physical interaction and form a stable hybrid material, in which the PBIs uniformly wrap the surfaces of the CNTs. Furthermore, PBIs serve as effective binding sites for the formation of platinum (Pt) nanoparticles to fabricate a ternary composite (CNT/PBIs/Pt). In this review article, we summarize the fundamental properties of the CNT/PBIs/Pt and discuss their potential as a new electrocatalyst for the PEFC in comparison with the conventional ones. Furthermore, potential applications of CNT/PBIs including use of the materials for oxygen reduction catalysts and reinforcement of PBI films are summarized.

Phase separation and water channel formation in sulfonated block copolyimide

We compared experimental and simulated data to investigate the phase separation and water channel formation of proton exchange membranes (PEMs) for fuel cell. Sulfonated block copolyimides (SPIs) were adopted as model polymers for experiments and simulations, and Nafion was used as a reference. Nafion and SPIs were observed to have different microscopic structures such as constituent atoms, backbone rigidity, and the locations of sulfonic acid groups, all of which significantly affect phenomenological properties at the macroscopic level such as density, water uptake, and proton conductivity. In particular, SPIs show much weaker microphase separation than Nafion, mainly due to the lower mobility of sulfonic acid groups and the existence of acceptable sites for hydrogen bonding even in hydrophobic segments, which impedes water channel formation for proton transport. As a result, the phase separation behavior and the resulting water channel formation are the major factors affecting macroscopic properties of PEMs such as water uptake and proton transport.