Electrochemical Polymer Electrolyte Membranes covers PEMs from fundamentals to applications, describing their structure, properties, characterization, synthesis, and use in electrochemical energy storage and solar energy conversion technologies. Featuring chapters authored by leading experts from academia and industry, this authoritative text: Disc

This volume explores the latest developments in the area of polymer electrolyte membranes (PEMs) used for high-temperature fuel cells. Featuring contributions from an international array of researchers, it presents a unified viewpoint on the operating principles of fuel cells, various methodologies used for the fabrication of PEMs, and issues related to the chemical and mechanical stabilities of the membranes. Special attention is given to the fabrication of electrospun nanocomposite membranes. The editors have consciously placed an emphasis on developments in the area of fast-growing and promising PEM materials obtained via hygroscopic inorganic fillers, solid proton conductors, heterocyclic solvents, ionic liquids, anhydrous H3PO4 blends, and heteropolyacids. This book is intended for fuel cell researchers and students who are interested in a deeper understanding of the organic–inorganic membranes used in fuel cells, membrane fabrication methodologies, properties and clean energy applications.

Anion exchange membranes (AEMs) are polymer-based electrolyte solids that conduct anions (OH-, HCO3-, Cl-, et al.), with positively charged groups bound covalently to the polymer backbones. There has been a strong and growing worldwide interest in the use of anion exchange membranes for electrochemical energy conversion and storage systems. Anion exchange membrane fuel cells (AEMFCs) have been regarded as promising energy conversion devices for stationary and mobile applications due to their potential low cost. To realize high-performance AEMFCs, new polymeric membranes are needed that are highly conductive and chemically stable. Herein, cross-linked, multication side chain, and fluorene side chain AEMs based on poly(2,6-dimethyl-1,4-phenylene oxide)s (PPO) were synthesized. PPO was chosen as an AEM substrate because of its ease of functionalization at large scale and relatively good stability and membrane properties. To produce anion conductive and durable polymer electrolytes for alkaline fuel cell applications, a series of cross-linked quaternary ammonium functionalized poly(2,6-dimethyl-1,4-phenylene oxide)s with mass-based ion exchange capacities (IEC) ranging from 1.80 to 2.55 mmol/g were synthesized via thiol-ene click chemistry. From small angle X-ray scattering (SAXS), it was found that the cross-linked membranes developed micro-phase separation between the polar PPO backbone and the hydrophobic alkyl side chains. The ion conductivity, dimensional stability, and alkaline durability of the cross-linked membranes were evaluated. The hydroxide ion conductivity of the cross-linked samples reached 60 mS/cm in liquid water at room temperature. The chemical stabilities of the membranes were evaluated under severe, accelerated aging conditions and degradation was quantified by measuring ion conductivity changes during aging. The cross-linked membranes retained their relatively high ion conductivity and good mechanical properties both in 1 M and 4 M NaOH at 80 °C after 500 h. Attenuated total reflection (ATR) spectra were used to study the degradation pathways of the membranes, and it was discovered that [beta]-hydrogen (Hofmann) elimination was likely to be the major pathway for degradation in these membranes. Side-chain containing AEMs with one, two or three cations per side chain were designed and synthesized, enabling a study of how the degree of polymer backbone functionalization and arrangement of cations on the side chain impact AEM properties. A systematic study of anion exchange membranes (AEMs) with multiple cations per side chain site was conducted to demonstrate how this motif can boost both the conductivity and stability of poly(2,6-dimethyl-1,4-phenylene oxide)-based AEMs. The highest conductivity, up to 99 mS/cm at room temperature, was observed for a triple-cation side chain AEM with 5 or 6 methylene groups between cations. This conductivity was considerably higher than AEM samples based on benzyltrimethyl ammonium or benzyldimethylhexyl ammonium groups with only one cation per side chain site. In addition to high conductivity, the multication side chain AEMs showed good alkaline and dimensional stabilities. High retention of ion exchange capacity (IEC) (93% retention) and ionic conductivity (90% retention) were observed for the triple-cation side chain AEMs during degradation testing in 1 M NaOH at 80 °C for 500 h. Based on the high-performance triple-cation side chain AEM, a Pt-catalyzed fuel cell with a peak power density of 364 mW/cm2 was achieved at 60 °C under 100% related humidity. Anion-conductive copolymers, poly(2,6-dimethyl-1,4-phenylene oxide)s containing fluorene side chains with pendant alkyltrimethylammonium groups, were synthesized via Suzuki-Miyaura coupling of aryl bromides with fluorene-boronic acids. The quaternized copolymers produced ductile, transparent membranes which were soluble in dimethyl formamide, dimethyl sulfoxide and methanol at room temperature. The fluorene side chain-containing membranes showed considerably higher hydroxide ion conductivities, up to 176 mS/cm at 80 °C, compared to that of typical anion exchange membranes based on the benzyltrimethyl ammonium moiety. The results of titration and hydroxide ion conductivity measurements demonstrated excellent chemical stability of the fluorene side chain-containing anion exchange membranes (AEMs), even after 1000 h immersion in 1 M NaOH at 80 °C. The results of this study suggest a scalable route for the preparation of AEMs for practical alkaline fuel cell applications. A unique approach was employed to toughen AEMs by crosslinking the AEMs using commercial Jeffamine additives. Compared to the BTMA40 membrane, the 10% Jeffamine cross-linked membrane demonstrated significantly higher elongation at break. To be specific, the hydrated BTMA40 membrane showed a 51.7% elongation at break, while the 10% Jeffamine cross-linked membrane had a 166.8 % elongation at break. Clearly, the introducing of hydrophilic cross-linked network greatly enhanced the toughness of the AEMs. Overall, this thesis details a number of strategies for the large-scale production of PPO-based anion exchange membranes. These strategies will be useful in going forward in the design and deployment of hydroxide, bromide, bicarbonate, and chloride-conducting membranes for water purification and electrochemical technology.

Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

This handbook serves as a guide to deploying battery energy storage technologies, specifically for distributed energy resources and flexibility resources. Battery energy storage technology is the most promising, rapidly developed technology as it provides higher efficiency and ease of control. With energy transition through decarbonization and decentralization, energy storage plays a significant role to enhance grid efficiency by alleviating volatility from demand and supply. Energy storage also contributes to the grid integration of renewable energy and promotion of microgrid.

This book covers a significant number of R&D projects, performed mostly after 2000, devoted to the understanding and prevention of performance degradation processes in polymer electrolyte fuel cells (PEFCs). The extent and severity of performance degradation processes in PEFCs were recognized rather gradually. Indeed, the recognition overlapped with a significant number of industrial dem- strations of fuel cell powered vehicles, which would suggest a degree of technology maturity beyond the resaolution of fundamental failure mechanisms. An intriguing question, therefore, is why has there been this apparent delay in addressing fun- mental performance stability requirements. The apparent answer is that testing of the power system under fully realistic operation conditions was one prerequisite for revealing the nature and extent of some key modes of PEFC stack failure. Such modes of failure were not exposed to a similar degree, or not at all, in earlier tests of PEFC stacks which were not performed under fully relevant conditions, parti- larly such tests which did not include multiple on–off and/or high power–low power cycles typical for transportation and mobile power applications of PEFCs. Long-term testing of PEFCs reported in the early 1990s by both Los Alamos National Laboratory and Ballard Power was performed under conditions of c- stant cell voltage, typically near the maximum power point of the PEFC.