Since their introduction by Sony in 1990, lithium-ion batteries (LIBs) have acquired a sizable market share. They have the best energy densities, a high open circuit voltage, a low self-discharge rate, no memory effect, and a slow loss of charge when not in use. These properties make them the most popular rechargeable batteries for portable gadgets, electric vehicles and aerospace applications.  They do, however, pose major safety issues since the electrolytes are made up of fluorinated salts dissolved in volatile organic solvents, the former being meta-stable at ambient temperature and the latter being flammable a with high vapour pressure. Thus, there is an urge to develop thermally and electrochemically stable non-fluorinated electrolytes to improve the safety and performance of batteries. Electrolytes based on ionic liquids (ILs) in general offer a range of suitable advantages including low volatility and high thermal and electrochemical stabilities,and can additionally be made fluorine-free. In general, their physicochemical properties are determined by the interactions between the cations and anions, which are controlled by the chemical functionalities present, with vast freedom in structural design to reduce these interactions and enhance also the ion mobilities.  In this study, favoring from of “structural design” three different families of fluorine-free ionic liquids-based electrolytes are designed and created. These families of ILs comprising n- tetrabutylphosphonium, imidazolium, pyridinium based cations and pyridine, pyrazine and ether functionalized salicylate-based anions. The structures and purity of these new ILs are characterized by using multinuclear NMR, FTIR and mass spectrometry. Several features and properties of the novel electrolytes are investigated; thermogravimetric analysis, differential scanning calorimetry, ionic conductivity and electrochemical stability. These studies are further complemented by using PFG NMR diffusometry to understand the possible interaction mechanisms between the oppositely charged ions within the electrolytes, and especially, the influence of Li+ addition in the IL-based electrolytes.

This dissertation is written in two sections. The first section deals with the development of methods for the estimation of the effective electrolytic surface area of rough and porous silver electrodes in alkaline electrolyte. Data are presented comparing the results of three different methods of surface area estimation. Model pore electrodes were also prepared and oxidized to study the reactions in a pore. Data for constant current oxidations of these electrodes is given. The second section deals with the potentiostatic oxidations of silver in alkaline electrolyte. Data are presented on the total charge acceptance versus applied potential for a potential range that runs from the potential required to first produce silver (I) oxide to that required to evolve oxygen off the surface of the electrode. The shape of this plot indicates the formation of two types of silver (I) oxide. Three oxidation reactions were noted. The first was the formation of silver (I) oxide. The second was the formation of silver (II) oxide. The nature of the third reaction is not yet known; however, some evidence indicates it is the formation of silver (III) oxide.

No description available.

No description available.

No description available.

Commercial lithium ion batteries use liquid electrolytes because of their high ionic conductivity (>10-3 S/cm) over a broad range of temperatures, high dielectric constant, and good electrochemical stability with the electrodes (mainly the cathode cathode). The disadvantages of their use in lithium ion batteries are that they react violently with lithium metal, have special packing needs, and have low lithium ion transference numbers (tLi+ = 0.2-0.3). These limitations prevent them from being used in high energy and power applications such as in hybrid electric vehicles (HEVs), plug in electric vehicles (EVs) and energy storage on the grid. Solid polymer electrolytes (SPEs) will be good choice for replacing liquid electrolytes in lithium/lithium ion batteries because of their increased safety and ease of processability. However, SPEs suffer from RT low ionic conductivity and transference numbers. There have been many approaches to increase the ionic conductivity in solid polymer electrolytes. These have focused on decreasing the crystallinity in the most studied polymer electrolyte, polyethylene oxide (PEO), on finding methods to promote directed ion transport, and on the development of single ion conductors, where the anions are immobile and only the Li+ ions migrate (i.e. tLi+ = 1). But these attempts have not yet achieved the goal of replacing liquid electrolytes with solid polymer electrolytes in lithium ion batteries. In order to increase ionic conductivity and lithium ion transference numbers in solid polymer electrolytes, I have focused on the development of multi-ionic lithium salts. These salts have very large anions, and thus are expected to have low tanion- and high tLi+ transference numbers. In order to make the anions dissociative, structures similar to those formed for mono-ionic salts, e.g. LiBF4 and lithium imides have been synthesized. Some of the multi-ionic salts have Janus-like structures and therefore can self-assemble in polar media. Further, it is possible that these salts may not form non-conductive ion pairs and less conductive ion triplets. First, we have prepared nanocomposite electrolytes from mixtures of two polyoctahedral silsesquioxanes (POSS) nanomaterials, each with a SiO1.5 core and eight side groups. POSS-PEG8 has eight polyethylene glycol side chains that have low glass transition (Tg) and melt (Tm) temperatures and POSS-phenyl7(BF3Li)3 is a Janus-like POSS with hydrophobic phenyl groups and -Si-O-BF3Li ionic groups clustered on one side of the SiO1.5 cube. The electron-withdrawing POSS cage and BF3 groups enable easy dissociation of the Li+. In the presence of polar POSS-PEG8, the hydrophobic phenyl rings of POSS-phenyl7(BF3Li)3 aggregate and crystallize, forming a biphasic morphology, in which the phenyl rings form the structural phase and the POSS-PEG8 forms the conductive phase. The -Si-O-BF3- Li+ groups of POSS-phenyl7(BF3Li)3 are oriented towards the polar POSS-PEG8 phase and dissociate so that the Li+ cations are solvated by the POSS-PEG8. The nonvolatile nanocomposite electrolytes are viscous liquids that do not flow under their own weight. POSS-PEG8/POSS-phenyl7(BF3Li)3 at O/Li = 16/1 has a conductivity, σ = 2.5 x 10-4 S/cm at 30°C, 17 x greater than POSS-PEG8/LiBF4, and a low activation energy (Ea ~ 3-4 kJ/mol); σ = 1.6 x 10-3 S/cm at 90°C and 1.5 x 10-5 S/cm at 10°C. The lithium ion transference number was tLi+ = 0.50 ± 0.01, due to reduced mobility of the large, bulky anion and the system exhibited low interfacial resistance that stabilized after 3 days (both at 80°C). Secondly, solid polymer electrolytes have been prepared from the same salt, POSS-phenyl7(BF3Li)3 and polyethylene oxide (PEO). These exhibit high ambient temperature conductivity, 4 x 10-4 S/cm, and transference number, tLi+ = 0.6. A two-phase morphology is proposed in which the hydrophobic phenyl groups cluster and crystallize, and the three -BF3- form an anionic pocket, with the Li+ ions solvated by the PEO phase. The high ionic conductivity results from interfacial migration of Li+ ions loosely bonded to three -BF3- anions and the ether oxygens of PEO. Physical crosslinks formed between PEO/Li+ chains and the POSS clusters account for the solid structure of the amorphous PEO matrix. The solid polymer electrolyte has an electrochemical stability window of 4.6 V and excellent interfacial stability with lithium metal. In order to further enhance the ionic conductivity of solid polymer electrolytes, we have made two improvements. First, we have used so called half cube structures, T4-POSS, that contain 4 phenyl groups on one side of a Si-O- ring, and 4 ionic groups on the other side, and so are true Janus structures. They contain a 4/4 ratio of phenyl/ionic groups, unlike the previous structures that contain 7 phenyl groups/3 ionic groups. At the same O/Li ratio, the ionic conductivity of [PhOSi(OLi)]4 with POSS-PEG8 is higher than POSS-phenyl7Li3 because of more Li+ dissociation in the former case. Second, we have increased the dissociation of the lithium salts by replacing the Si-O-BF3Li groups with Si-(C3H4NLiSO2CF3)4. Both T4-POSS-(C3H4NLiSO2CF3)4 and POSS-(C3H4NLiSO2CF3)8 have been synthesized and characterized, with some preliminary conductivity data obtained. / Chemistry

Congestive heart failure is commonly treated with a low sodium diet and diuretic. The purpose of this treatment is the reduction of preload, or blood volume presented to the diseased cardiac muscle. The purpose of this study was to assess the roles of dietary sodium and furosemide on cardiac function, plasma electrolyte concentrations, and the renin-angiotensin-aldosterone system, in healthy canines. Twenty mixed-breed canines were allotted to one of four groups, Group I - Dogs fed low sodium diet (0.08% sodium), Group II - Dogs fed high sodium diet (1.0% sodium), Group III - Dogs fed low sodium (0.08%) and treated with furosemide (2 mg/kg orally (PO) every twelve hours (BID)), and Group IV - Dogs fed high sodium (1.0%) and furosemide ( 2 mg/kg PO BID). Cardiac function was assessed via echocardiography on days 0, 21,and 53. Plasma electrolyte concentrations were measured on days 0, 21, and 35. Activation of the renin-angiotensin-aldosterone system was evaluated on days 0, 21, 35, and 53. Low and high sodium diet with and without furosemide treatment did not alter cardiac function, plasma sodium, or plasma potassium concentrations. However, furosemide treatment combined with a low sodium diet resulted in the lowest plasma chloride concentrations, on days 21 and 35 (p<0.05). Furthermore, furosemide treatment resulted in significant alterations in the renin-angiotensin-aldosterone system, on days 21, 35, and 53, (p < 0.0001). Furosemide treatment significantly increased renin activity and aldosterone concentration. The interaction between furosemide and the low sodium diet yielded a greater increase in plasma renin activity and plasma aldosterone concentrations than furosemide administration with the high sodium diet. These results suggest direct activation of the renin-angiotensin-aldosterone system by furosemide. Future research is warranted in congestive heart failure subjects, due to the adverse affects of decreased plasma chloride concentrations and activation of the renin-angiotensin-aldosterone system. / Master of Science

Soft materials are indispensable components of energy storage and conversion technologies necessary for the renewable energy transition. Two key examples are electrolytes used in solid-state batteries and ion-exchange membranes used in electrolysis and electrodialysis. The figures of merit for these applications are often summarized using upper-bound relationships, which define the best possible combination of performance metrics for a given material. A promising route to break the upper-bound and to improve upon the state-of-the-art is engineering materials at the nanoscale. Two commonly employed strategies are the use of block copolymers and polymer nanocomposites. In the former, the sequence of different monomers along the backbone of the polymer chain is varied; in the latter, ceramic nanoparticles are mixed with polymers and processed to achieve different dispersion states. In both of these classes of materials, the self-assembly of molecular and colloidal components controls the structure and function of the resulting material. This dissertation investigates these structure-property relationships in model soft nanomaterials, namely colloids, polymer nanocomposites, and ion-exchange membranes, using experiments, molecular dynamics simulations, and theory. The dissertation can be divided into three parts. The first, Chapters 2 and 3, investigates polymer and polymer nanocomposite electrolytes for applications in solid-state Li batteries. Chapter 2 investigates the coarse-graining and force field parameterization of polymer electrolytes for molecular dynamics simulations. Chapter 3 reports the experimental characterization of polymer nanocomposite electrolytes, with a key focus on understanding how the particle dispersion state affects the ionic conductivity and mechanical reinforcement of the composite. The second part, Chapters 4 and 5, studies fundamental structure-property relationships in two types of polymer nanocomposites. In Chapter 4, the surface chemistry of hydrophilic silica nanoparticles is altered to promote miscibility in organic solvents and in semicrystalline polymers. In these "bare" nanocomposites, the particles are stabilized against aggregation via the adsorption of a polymer bound layer, which is quantitatively studied via small angle X-ray scattering. In Chapter 5, the surface-modified particles are densely grafted with polymer chains via surface-initiated polymerization to obtain matrix-free polymer grafted nanoparticle films. The collective dynamics of the nanoparticle cores in these self-supporting films, where all of the polymer is grafted to the particle surface, is then measured using X-ray photocorrelation spectroscopy at a variety of temperatures. In Chapters 6 and 7, random copolymer chemistries are used to create cation- and anion-exchange membranes, respectively, with controlled ion-exchange capacity and swelling behavior. The key finding of Chapter 6 is that water-lean cation-exchange membranes selectively transport ions with low free energies of hydration, allowing the design of specific-ion selective electrodialysis stacks for Li+ recovery applications. The analogous properties of anion-exchange membranes are suggested as an avenue for future research.

Le facteur clé limitant le déploiement des accumulateurs au lithium métal est dû à la formation de dendrites de lithium métallique à l'anode au cours de la recharge. Une solution consiste à employer un électrolyte solide polymère. Un copolymère à blocs est composé d'un ou plusieurs blocs conducteurs à base de POE (poly(oxyde d'éthylène)), linéaire ou branchée, dopés en sel de lithium (LiTFSI) et de blocs de renforts mécaniques qui idéalement mitigent la croissance dendritique. Ces matériaux ont la particularité de s'auto-assembler en domaines nanométriques. Les interfaces entre les domaines génèrent de bonnes propriétés mécaniques à l'échelle macroscopique tandis que localement la dynamique des chaînes POE demeure élevée, assurant la conduction ionique.Ce travail de thèse porte sur les caractérisations physico-chimiques d'électrolytes copolymères, selon différentes architectures (diblocs, triblocs et étoilées) et de l'optimisation de leurs compositions. Une étude fondamentale des polymères dopés en sel a mis en évidence les principaux mécanismes de transport ionique, ainsi que l'impact des groupes terminaux à faible masse molaire sur la conductivité et la viscosité. Cette étape a permis de sélectionner les meilleurs candidats. L'étude de la stabilité des électrolytes vis-à-vis du lithium a été menée. Après avoir formulé des cathodes, des batteries plastiques ont été assemblées et testées avec succès par cyclages galvanostatiques, en température [40°C-100°C] et à des régimes élevés. Enfin, un prototype de 6 mAh a réalisé plus de 400 cycles à des régimes C/4 et D/2 à 100°C. / The key limiting factor for the deployment of Lithium metal batteries is the formation of lithium dendrites at the anode during recharge. One solution consists in the use of a solid polymer electrolyte. A bloc copolymer is composed of one or several conductive blocks based on PEO (poly(ethylene oxide)), linear or branched, doped with a lithium salt (LiTFSI) and reinforced blocks that ideally mitigate the dendritic growth. These materials can self-organize in nanometric domains. The interfaces between the domains generate sufficient mechanical properties at the macroscopic level whilst, locally, the PEO chain dynamics remain high, ensuring ionic conduction.This thesis deals with physico-chemical characterizations of these copolymer electrolytes, with different architectures (diblock, triblock and star shaped), and the optimization of their composition. A fundamental study of doped polymers highlighted the main mechanisms of ionic transport and the impact of the end groups at low molar mass on conductivity and viscosity. This step enabled a selection of the best candidates to be made. A study of the electrolyte stability with respect to lithium was carried out. After the formulation of cathodes, plastic batteries were assembled and successfully tested by galvanostatic cycling under temperature [40°C-100°C] and high regime. Finally, a 6 mAh prototype realised more than 400 cycles under the regime C/4 and D/2 at 100°C.

In recent years, electrochemical capacitors have emerged as devices with the potential to enable major advances in electrical energy storage. Electrochemical capacitors (ECs) are akin to conventional capacitors but employ higher surface-area electrodes and thinner dielectrics to achieve larger capacitances. This helps ECs to attain energy densities greater than those of conventional capacitors and power densities greater than those of batteries. Akin to conventional capacitors, ECs also have high cycle-lives and can be charged and discharged rapidly. But ECs are yet to match the energy densities of mid to high-end batteries and fuel cells. On the basis of mechanism involved in the charge-storage process, ECs are classified as electrical double-layer capacitors (EDLCs) or pseudocapacitors. Charge storage in EDLCs and pseudocapacitors is brought about by non-faradaic and faradaic processes, respectively. Faradaic process, such as an oxidation-reduction reaction, involves the transfer of charge between electrode and electrolyte. By contrast, a non-faradaic process does not use a chemical mechanism and charges are distributed on surfaces by physical processes that do not involve any chemical reaction. ECs employ both aqueous and non-aqueous electrolytes in either liquid or solid form, the latter providing the advantages of freedom from leakage of any liquid component, compactness, reliability and large operating potential-window. In the literature, polymer electrolytes are the most widely studied solid electrolytes. Complexation of functional-groups of certain polymers with cations results in the formation of polymer-cation complexes commonly referred to as solid-polymer electrolytes (SPEs). Mixing a polymer with an alkali metal salt dissolved in an organic solvent result in the formation of a polymer gel electrolyte. Organic solvents with low molecular-weights, such as ethylene carbonate and propylene carbonate, employed in polymer gel electrolytes are commonly referred to as plasticizers. When water is used as a plasticizer, the polymer electrolyte is called a polymer hydrogel electrolyte. Part I of the thesis is directed to studies pertaining to Polymer Hydrogel Electrolytes for Electrochemical Capacitors and comprises four sections. After a brief survey of literature on polymer hydrogel electrolytes employed in ECs in Section I.1, Section I.2 of Part I describes the studies on electrochemical capacitors employing cross-linked poly (vinyl alcohol) hydrogel membrane electrolytes with varying perchloric acid dopant concentration. Acidic poly (vinyl alcohol) hydrogel membrane electrolytes (PHMEs) with different perchloric acid concentrations are prepared by cross-linking poly (vinyl alcohol) with glutaraldehyde in the presence of a protonic acid acting as a catalyst under ambient conditions. PHMEs are characterized by scanning electron microscopy and temperature-modulated differential scanning calorimetry in conjunction with relevant electrochemical techniques. An optimised electrochemical capacitor assembled employing PHME in conjunction with black pearl carbon (BPC) electrodes yields a maximum specific capacitance value of about 96 F g-1, phase angle value of about 79o and a discharge capacitance value of about 88 F g-1. Section I.3 of Part I describes the studies on cross-linked poly (vinyl alcohol)/ploy (acrylic acid) blend hydrogel electrolytes for electrochemical capacitors. Acidic poly (vinyl alcohol)/poly (acrylic acid) blend hydrogel electrolytes (BHEs) have been prepared by cross-linking poly (vinyl alcohol)/poly (acrylic acid) blend with glutaraldehyde in presence of perchloric acid. These acidic BHEs have been treated suitably to realize alkaline and neutral BHEs. Thermal characteristics and glass-transition behavior of BHEs have been followed by differential scanning calorimetry. Ionic conduction in acidic BHEs has been found to take place by Grötthus-type mechanism while polymer segmental motion mechanism is predominantly responsible for ion motion in alkaline and neutral BHEs. Ionic conductivity of BHEs has been found to range between 10-3 and 10-2 S cm-1 at 298 K. Electrochemical capacitors assembled with acidic PVA hydrogel electrolyte yield a maximum specific capacitance of about 60 and 1000 F g-1 with BPC and RuOx.xH2O/C electrodes, respectively. Section I.4 of Part I describes the studies on gelatin hydrogel electrolytes and their application to electrochemical capacitors. Gelatin hydrogel electrolytes (GHEs) with varying NaCl concentrations have been prepared by cross-linking an aqueous solution of gelatin with aqueous glutaraldehyde under ambient conditions, and characterized by scanning electron microscopy, temperature-modulated differential scanning calorimetry, cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic chronopotentiometry. Glass transition temperatures for GHEs range between 340 and 377 K depending on the dopant concentration. Ionic conductivity behavior of GHEs is studied with varying concentrations of gelatin, glutaraldehyde and NaCl, and conductivity values are found to vary between 10-3 and 10-1 S cm-1 under ambient conditions. GHEs have a potential window of about 1 V with BPC electrodes. The ionic conductivity of pristine and 0.25 N NaCl-doped GHEs follows Arrhenius behavior with activation energy values of 1.9×10-4 and 1.8×10-4 eV, respectively. Electrochemical capacitors employing GHEs in conjunction with black pearl carbon electrodes are assembled and studied. Optimal values for capacitance, phase angle, and relaxation time constant of about 81 F g-1, 75o, and 0.03 s are obtained for 3 M NaCl-doped GHE, respectively. EC with pristine GHE exhibits continuous cycle life for about 4.3 h as against 4.7 h for the electrochemical capacitor with 3 M NaCl-doped GHE. Unlike electrochemical capacitors, fuel cells do not store the charge internally but instead use a continuous supply of fuel from an external storage tank. Thus, fuel cells have the potential to solve the most challenging problem associated with the electrochemical capacitors, namely their limited energy-density. A fuel cell is an electrochemical power source with advantages of both the combustion engine and the battery. Like a combustion engine, a fuel cell will run as long as it is provided with fuel; and like a battery, fuel cells convert chemical energy directly to electrical energy. As an electrochemical power source, fuel cells are not subjected to the Carnot limitations of combustion (heat) engines. A fuel cell operates quietly and efficiently and, when hydrogen is used as a fuel, it generates only power and potable water. Thus, a fuel cell is a so called ‘zero-emission engine’. In the past, several fuel cell concepts have been tested in various laboratories but the systems that are being potentially considered for commercial developments are: (i) Alkaline Fuel Cells (AFCs), (ii) Phosphoric Acid Fuel Cells (PAFCs), (iii) Polymer Electrolyte Fuel Cells (PEFCs), (iv) Solid-Polymer-Electrolyte-Direct Methanol Fuel Cells (SPE-DMFCs), (v) Molten Carbonate Fuel Cells (MCFCs) and (vi) Solid Oxide Fuel Cells (SOFCs). Among the aforesaid systems, PEFCs that employ hydrogen as fuel are considered attractive power systems for quick start-up and ambient-temperature operations. Ironically, however, hydrogen as fuel is not available freely in the nature. Accordingly, it has to be generated from a readily available hydrogen carrying fuel such as natural gas, which needs to be reformed. But, such a process leads to generation of hydrogen with some content of carbon monoxide, which even at minuscule level is detrimental to the fuel cell performance. Pure hydrogen can be generated through water electrolysis but hydrogen thus generated needs to be stored as compressed / liquefied gas, which is cost-intensive. Therefore, certain hydrogen carrying organic fuels such as methanol, ethanol, propanol, ethylene glycol, and diethyl ether have been considered for fuelling PEFCs directly. Among these, methanol with a hydrogen content of about 13 wt. % (specific energy = 6.1 kWh kg-1) is the most attractive organic liquid. PEFCs using methanol directly as fuel are referred to as SPE-DMFCs. But SPE-DMFCs suffer from methanol crossover across the polymer electrolyte membrane, which affects the cathode performance and hence the cell performance during its operation. SPE-DMFCs also have inherent limitations of low open-circuit-potential and low electrochemical-activity. An obvious solution to the aforesaid problems is to explore other promising hydrogen carrying fuels such as sodium borohydride, which has a hydrogen content of about 11 wt. %. Such fuel cells are called direct borohydride fuel cells (DBFCs). Part II of the thesis includes studies on direct borohydride fuel cells and comprises three sections. After a brief introduction to DBFCs in section II.1, Section II.2 describes studies on an alkaline direct borohydride fuel cell with hydrogen peroxide as oxidant. A peak power density of about 150 mW cm-2 at a cell voltage of 540 mV could be achieved from the optimized DBFC operating at 70oC. Section II.3 describes studies on poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells. This DBFC employs a poly (vinyl alcohol) hydrogel membrane as electrolyte, an AB5 Misch metal alloy as anode, and a gold-plated stainless steel mesh as cathode in conjunction with aqueous alkaline solution of sodium borohydride as fuel and aqueous acidified solution of hydrogen peroxide as oxidant. The performance of the PHME-based DBFC in respect of peak power outputs, ex-situ cross-over of oxidant, fuel, anolyte and catholyte across the membrane electrolytes, utilization efficiencies of fuel and oxidant as also cell performance durability under ambient conditions are compared with a similar DBFC employing a Nafion®-117 membrane electrolyte (NME). Peak power densities of about 30 and 40 mW cm-2 are observed for the DBFCs with PHME and NME, respectively. The PHME and NME-based DBFCs exhibit cell potentials of about 1.2 and 1.4 V, respectively, at a load current density of 10 mA cm-2 for 100 h. Publications of Nurul Alam Choudhury 1. Gelatin hydrogel electrolytes and their application to electrochemical supercapacitors, N. A. Choudhury, S. Sampath, and A. K. Shukla, J. Electrochem. Soc., 155 (2008) A74. 2. Cross-linked polymer hydrogel electrolytes for electrochemical capacitors, N. A. Choudhury, A. K. Shukla, S. Sampath, and S. Pitchumani, J. Electrochem. Soc., 153 (2006) A614. 3. Hydrogel-polymer electrolytes for electrochemical capacitors: an overview, N. A. Choudhury, S. Sampath, and A. K. Shukla, Energy and Environmental Science (In Press). 4. Cross-linked poly (vinyl alcohol) hydrogel membrane electrolytes with varying perchloric acid dopant concentration and their application to electrochemical capacitors, N. A. Choudhury, S. Sampath, and A. K. Shukla, J. Chem. Sc. (Submitted) 5. An alkaline direct borohydride fuel cell with hydrogen peroxide as oxidant, N. A. Choudhury, R. K. Raman, S. Sampath, and A. K. Shukla, J. Power Sources, 143 (2005) 1. 6. Poly (vinyl alcohol) hydrogel membrane as electrolyte for direct borohydride fuel cells, N. A. Choudhury, S. K. Prashant, S. Pitchumani, P. Sridhar, and A. K. Shukla, J. Chem. Sc. (Submitted). 7. A phenyl-sulfonic acid anchored carbon-supported platinum catalyst for polymer electrolyte fuel cell electrodes, G. Selvarani, A. K. Sahu, N. A. Choudhury, P. Sridhar, S. Pitchumani, and A. K. Shukla, Electrochim. Acta, 52 (2007) 4871. 8. A high-output voltage direct borohydride fuel cell, R. K. Raman, N. A. Choudhury, and A. K. Shukla, Electrochem. Solid-State Lett., 7 (2004) A 488. 9. Carbon-supported Pt-Fe alloy as a methanol-resistant oxygen-reduction catalyst for direct methanol fuel cells, A. K. Shukla, R. K. Raman, N. A. Choudhury, K. R. Priolkar, P. R. Sarode, S. Emura, and R. Kumashiro, J. Electroanal. Chem., 563 (2004) 181.