1. PVA-SSA-HPA mixed-matrix-membrane electrolytes for DMFCs
- Author
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A. Jalajakshi, Santoshkumar D. Bhat, Abhishek Banerjee, N. Chandrakumar, S. Pitchumani, Ashok Kumar Shukla, Akhila Kumar Sahu, Christy George, and Parthasarathi Sridhar
- Subjects
Vinyl alcohol ,Peak power densities ,Ion exchange capacity ,Ex situ ,Ion exchange membranes ,Inorganic fillers ,Silicotungstic acid ,Membrane electrolytes ,chemistry.chemical_compound ,Electrolytes ,NMR spectroscopy ,Methanol fuels ,Nafion ,Polymer chemistry ,Materials Chemistry ,Electrochemistry ,Methanol crossover rates ,Phosphotungstic acid ,Methanol fuel ,Sulfur compounds ,Nuclear magnetic resonance spectroscopy ,Osmotic drag ,Release kinetics ,Mixed-matrix membranes ,Renewable Energy, Sustainability and the Environment ,Methanol ,Mechanical permeability ,Condensed Matter Physics ,matrix ,Phosphomolybdic acid ,Mechanical stability ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Membrane ,chemistry ,Chemical engineering ,Heteropoly acids ,Sorption ,Direct methanol fuel cells (DMFC) ,Protons ,Sorption capability ,Methanol permeability ,Ion exchange ,Proton conduction - Abstract
Stabilized forms of heteropolyacids (HPAs), namely phosphomolybdic acid (PMA), phosphotungstic acid (PTA), and silicotungstic acid (STA), are incorporated into poly (vinyl alcohol) (PVA) cross-linked with sulfosuccinic acid (SSA) to form mixed-matrix membranes for application in direct methanol fuel cells (DMFCs). Bridging SSA between PVA molecules not only strengthens the network but also facilitates proton conduction in HPAs. The mixed-matrix membranes are characterized for their mechanical stability, sorption capability, ion-exchange capacity, and wetting in conjunction with their proton conductivity, methanol permeability, and DMFC performance. Methanol-release kinetics is studied ex situ by volume-localized NMR spectroscopy (employing point-resolved spectroscopy'') with the results clearly demonstrating that the incorporation of certain inorganic fillers in PVA-SSA viz., STA and PTA, retards the methanol-release kinetics under osmotic drag compared to Nafion, although PVA-SSA itself exhibits a still lower methanol permeability. The methanol crossover rate for PVA-SSA-HPA-bridged-mixed-matrix membranes decreases dramatically with increasing current density rendering higher DMFC performance in relation to a DMFC using a pristine PVA-SSA membrane. A peak power density of 150 mW/cm(2) at a load current density of 500 mA/cm(2) is achieved for the DMFC using a PVA-SSA-STA-bridged-mixed-matrix-membrane electrolyte. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3465653] All rights reserved.
- Published
- 2010
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