Fuel Cell Basics 2012 V2.Key
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Electrochemical Cells
Electrochemical cells = electronic conductor If two different + surrounding electrolytes are used: electrolyte electrode compartment Galvanic cell: electrochemical cell in which electricity is produced as a result of a spontaneous reaction (e.g., batteries, fuel cells, electric fish!) Electrolytic cell: electrochemical cell in which a non-spontaneous reaction is driven by an external source of current Nils Walter: Chem 260 Reactions at electrodes: Half-reactions Redox reactions: Reactions in which electrons are transferred from one species to another +II -II 00+IV -II → E.g., CuS(s) + O2(g) Cu(s) + SO2(g) reduced oxidized Any redox reactions can be expressed as the difference between two reduction half-reactions in which e- are taken up Reduction of Cu2+: Cu2+(aq) + 2e- → Cu(s) Reduction of Zn2+: Zn2+(aq) + 2e- → Zn(s) Difference: Cu2+(aq) + Zn(s) → Cu(s) + Zn2+(aq) - + - → 2+ More complex: MnO4 (aq) + 8H + 5e Mn (aq) + 4H2O(l) Half-reactions are only a formal way of writing a redox reaction Nils Walter: Chem 260 Carrying the concept further Reduction of Cu2+: Cu2+(aq) + 2e- → Cu(s) In general: redox couple Ox/Red, half-reaction Ox + νe- → Red Any reaction can be expressed in redox half-reactions: + - → 2 H (aq) + 2e H2(g, pf) + - → 2 H (aq) + 2e H2(g, pi) → Expansion of gas: H2(g, pi) H2(g, pf) AgCl(s) + e- → Ag(s) + Cl-(aq) Ag+(aq) + e- → Ag(s) Dissolution of a sparingly soluble salt: AgCl(s) → Ag+(aq) + Cl-(aq) − 1 1 Reaction quotients: Q = a − ≈ [Cl ] Q = ≈ Cl + a + [Ag ] Ag Nils Walter: Chem 260 Reactions at electrodes Galvanic cell: -
3 PRACTICAL APPLICATION BATTERIES and ELECTROLYSIS Dr
ELECTROCHEMISTRY – 3 PRACTICAL APPLICATION BATTERIES AND ELECTROLYSIS Dr. Sapna Gupta ELECTROCHEMICAL CELLS An electrochemical cell is a system consisting of electrodes that dip into an electrolyte and in which a chemical reaction either uses or generates an electric current. A voltaic or galvanic cell is an electrochemical cell in which a spontaneous reaction generates an electric current. An electrolytic cell is an electrochemical cell in which an electric current drives an otherwise nonspontaneous reaction. Dr. Sapna Gupta/Electrochemistry - Applications 2 GALVANIC CELLS • Galvanic cell - the experimental apparatus for generating electricity through the use of a spontaneous reaction • Electrodes • Anode (oxidation) • Cathode (reduction) • Half-cell - combination of container, electrode and solution • Salt bridge - conducting medium through which the cations and anions can move from one half-cell to the other. • Ion migration • Cations – migrate toward the cathode • Anions – migrate toward the anode • Cell potential (Ecell) – difference in electrical potential between the anode and cathode • Concentration dependent • Temperature dependent • Determined by nature of reactants Dr. Sapna Gupta/Electrochemistry - Applications 3 BATTERIES • A battery is a galvanic cell, or a series of cells connected that can be used to deliver a self-contained source of direct electric current. • Dry Cells and Alkaline Batteries • no fluid components • Zn container in contact with MnO2 and an electrolyte Dr. Sapna Gupta/Electrochemistry - Applications 4 ALKALINE CELL • Common watch batteries − − Anode: Zn(s) + 2OH (aq) Zn(OH)2(s) + 2e − − Cathode: 2MnO2(s) + H2O(l) + 2e Mn2O3(s) + 2OH (aq) This cell performs better under current drain and in cold weather. It isn’t truly “dry” but rather uses an aqueous paste. -
Elements of Electrochemistry
Page 1 of 8 Chem 201 Winter 2006 ELEM ENTS OF ELEC TROCHEMIS TRY I. Introduction A. A number of analytical techniques are based upon oxidation-reduction reactions. B. Examples of these techniques would include: 1. Determinations of Keq and oxidation-reduction midpoint potentials. 2. Determination of analytes by oxidation-reductions titrations. 3. Ion-specific electrodes (e.g., pH electrodes, etc.) 4. Gas-sensing probes. 5. Electrogravimetric analysis: oxidizing or reducing analytes to a known product and weighing the amount produced 6. Coulometric analysis: measuring the quantity of electrons required to reduce/oxidize an analyte II. Terminology A. Reduction: the gaining of electrons B. Oxidation: the loss of electrons C. Reducing agent (reductant): species that donates electrons to reduce another reagent. (The reducing agent get oxidized.) D. Oxidizing agent (oxidant): species that accepts electrons to oxidize another species. (The oxidizing agent gets reduced.) E. Oxidation-reduction reaction (redox reaction): a reaction in which electrons are transferred from one reactant to another. 1. For example, the reduction of cerium(IV) by iron(II): Ce4+ + Fe2+ ! Ce3+ + Fe3+ a. The reduction half-reaction is given by: Ce4+ + e- ! Ce3+ b. The oxidation half-reaction is given by: Fe2+ ! e- + Fe3+ 2. The half-reactions are the overall reaction broken down into oxidation and reduction steps. 3. Half-reactions cannot occur independently, but are used conceptually to simplify understanding and balancing the equations. III. Rules for Balancing Oxidation-Reduction Reactions A. Write out half-reaction "skeletons." Page 2 of 8 Chem 201 Winter 2006 + - B. Balance the half-reactions by adding H , OH or H2O as needed, maintaining electrical neutrality. -
Advances in Materials Design for All-Solid-State Batteries: from Bulk to Thin Films
applied sciences Review Advances in Materials Design for All-Solid-state Batteries: From Bulk to Thin Films Gene Yang 1, Corey Abraham 2, Yuxi Ma 1, Myoungseok Lee 1, Evan Helfrick 1, Dahyun Oh 2,* and Dongkyu Lee 1,* 1 Department of Mechanical Engineering, College of Engineering and Computing, University of South Carolina, Columbia, SC 29208, USA; [email protected] (G.Y.); [email protected] (Y.M.); [email protected] (M.L.); [email protected] (E.H.) 2 Chemical and Materials Engineering Department, Charles W. Davidson College of Engineering, San José State University, San José, CA 95192-0080, USA; [email protected] * Correspondence: [email protected] (D.O.); [email protected] (D.L.) Received: 15 June 2020; Accepted: 7 July 2020; Published: 9 July 2020 Featured Application: All solid-state lithium batteries, all solid-state thin-film lithium batteries. Abstract: All-solid-state batteries (SSBs) are one of the most fascinating next-generation energy storage systems that can provide improved energy density and safety for a wide range of applications from portable electronics to electric vehicles. The development of SSBs was accelerated by the discovery of new materials and the design of nanostructures. In particular, advances in the growth of thin-film battery materials facilitated the development of all solid-state thin-film batteries (SSTFBs)—expanding their applications to microelectronics such as flexible devices and implantable medical devices. However, critical challenges still remain, such as low ionic conductivity of solid electrolytes, interfacial instability and difficulty in controlling thin-film growth. In this review, we discuss the evolution of electrode and electrolyte materials for lithium-based batteries and their adoption in SSBs and SSTFBs. -
Advancing Focused Ion Beam Characterization for Next Generation Lithium-Ion Batteries
UC San Diego UC San Diego Electronic Theses and Dissertations Title Advancing Focused Ion Beam Characterization for Next Generation Lithium-Ion Batteries Permalink https://escholarship.org/uc/item/3sh5k04b Author Lee, Jungwoo Publication Date 2018 Peer reviewed|Thesis/dissertation eScholarship.org Powered by the California Digital Library University of California UNIVERSITY OF CALIFORNIA SAN DIEGO Advancing Focused Ion Beam Characterization for Next Generation Lithium-Ion Batteries A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in NanoEngineering by Jungwoo Zema Lee Committee in charge: Professor Ying Shirley Meng, Chair Professor David P. Fenning Professor Eric E. Fullerton Professor Olivia A. Graeve Professor Ping Liu 2018 Copyright Jungwoo Zema Lee, 2018 All rights reserved. The Dissertation of Jungwoo Zema Lee is approved, and it is acceptable in quality and form for publication on microfilm and electronically: Chair University of California San Diego 2018 iii DEDICATION To my given and chosen family iv TABLE OF CONTENTS Signature Page ..................................................................................................................... iii Dedication ............................................................................................................................ iv Table of Contents ................................................................................................................ v List of Abbreviations ......................................................................................................... -
Chapter 13: Electrochemical Cells
March 19, 2015 Chapter 13: Electrochemical Cells electrochemical cell: any device that converts chemical energy into electrical energy, or vice versa March 19, 2015 March 19, 2015 Voltaic Cell -any device that uses a redox reaction to transform chemical potential energy into electrical energy (moving electrons) -the oxidizing agent and reducing agent are separated -each is contained in a half cell There are two half cells in a voltaic cell Cathode Anode -contains the SOA -contains the SRA -reduction reaction -oxidation takes place takes place - (-) electrode -+ electrode -anions migrate -cations migrate towards the anode towards cathode March 19, 2015 Electrons move through an external circuit from the anode to cathode Electricity is produced by the cell until one of the reactants is used up Example: A simple voltaic cell March 19, 2015 When designing half cells it is important to note the following: -each half cell needs an electrolyte and a solid conductor -the electrode and electrolyte cannot react spontaneously with each other (sometimes carbon and platinum are used as inert electrodes) March 19, 2015 There are two kinds of porous boundaries 1. Salt Bridge 2. Porous Cup · an unglazed ceramic cup · tube filled with an inert · separates solutions but electrolyte such as NaNO allows ions to pass 3 through or Na2SO4 · the ends are plugged so the solutions are separated, but ions can pass through Porous boundaries allow for ions to move between two half cells so that charge can be equalized between two half cells 2+ 2– electrolyte: Cu (aq), SO4 (aq) 2+ 2– electrolyte: Zn (aq), SO4 (aq) electrode: zinc electrode: copper March 19, 2015 Example: Metal/Ion Voltaic Cell V Co(s) Zn(s) Co2+ SO 2- 4 2+ SO 2- Zn 4 Example: A voltaic cell with an inert electrode March 19, 2015 Example Label the cathode, anode, electron movement, ion movement, and write the half reactions taking place at each half cell. -
Bipolar Nickel-Metal Hydride Battery Being Developed
Bipolar Nickel-Metal Hydride Battery Being Developed Electro Energy's bipolar nickel-metal hydride battery design layout-two parallel, 24-cell stacks. (Copyright Electro Energy; used with permission.) The NASA Lewis Research Center has contracted with Electro Energy, Inc., to develop a bipolar nickel-metal hydride battery design for energy storage on low-Earth-orbit satellites (NASA contract NAS3-27787). The objective of the bipolar nickel-metal hydride battery development program is to approach advanced battery development from a systems level while incorporating technology advances from the lightweight nickel electrode field, hydride development, and design developments from nickel-hydrogen systems. This will result in a low-volume, simplified, less-expensive battery system that is ideal for small spacecraft applications. The goals of the program are to develop a 1-kilowatt, 28-volt (V), bipolar nickel-metal hydride battery with a specific energy of 100 watt-hours per kilogram (W-hr/kg), an energy density of 250 W-hr/liter and a 5-year life in low Earth orbit at 40- percent depth-of-discharge. Electro Energy has teamed with Rhône-Poulenc, Eagle-Picher Industries, Inc., Rutgers University, and Design Automation Associates to provide a well-integrated battery design. Electro Energy is the prime contractor responsible for the overall management of the program, battery design and development, component development and testing, and cell and battery testing. Rhône-Poulenc is responsible for the metal hydride component development and improvement. Eagle-Picher is supporting component and hardware development, battery design, fabrication procedures, trade studies, and documentation. Rutgers is providing treated material for the nickel electrodes in the batteries as well as analytical support for new and cycled cell components. -
Section 3.4 Fuel Cells
2016 FUEL CELLS SECTION 3.4 Fuel Cells Fuel cells efficiently convert diverse fuels directly into electricity without combustion, and they are key elements of a broad portfolio for building a competitive, secure, and sustainable clean energy economy. They offer a broad range of benefits, including reduced greenhouse gas emissions; reduced oil consumption; expanded use of renewable power (through the use of hydrogen derived from renewable resources as a transportation fuel as well as for energy storage and transmission); highly efficient energy conversion; fuel flexibility (use of diverse, domestic fuels, including hydrogen, natural gas, biogas, and methanol); reduced air pollution, criteria pollutants, water use; and highly reliable grid support. Fuel cells also have numerous advantages that make them appealing for end users, including quiet operation, low maintenance needs, and high reliability. Because of their broad applicability and diverse uses, fuel cells can address critical challenges in all energy sectors: commercial, residential, industrial, and transportation. The fuel cell industry had revenues of approximately $2.2 billion in 2014, an increase of almost $1 billion over revenues in 2013.1 The largest markets for fuel cells today are in stationary power, portable power, auxiliary power units, backup power, and material handling equipment. Approximately 155,000 fuel cells were shipped worldwide in the four-year period from 2010 through 2013, accounting for 510–583 MW of fuel cell capacity.2 In 2014 alone, more than 50,000 fuel cells accounting for over 180 MW of capacity were shipped.1 In transportation applications, manufacturers have begun to commercialize fuel cell electric vehicles (FCEVs). Hyundai and Toyota have recently introduced their FCEVs in the marketplace, and Honda is set to launch its new FCEV in the market in 2016. -
Iron Based Cathode Catalyst for Alkaline Fuel Cells Thesis Presented in Partial Fulfillment of the Requirements for Honors Resea
Iron Based Cathode Catalyst for Alkaline Fuel Cells Thesis Presented in Partial Fulfillment of the Requirements for Honors Research Distinction at The Ohio State University By Christopher Bruening Undergraduate Program in Chemical Engineering The Ohio State University 2014 Thesis Committee: Dr. Umit Ozkan, Advisor Dr. Kurt Koelling Copyright by Christopher Bruening 2014 Abstract Alkaline fuel cells take advantage of the reaction between hydrogen and oxygen to produce water and an electrical current. During the reaction, a hydroxide ion passes through a membrane from the oxygen side cathode to the hydrogen side anode. Previous research had been conducted on synthesis and evaluation of iron based catalysts for PEM fuel cells by the Heterogeneous Catalysis Research Group at The Ohio State University. PEM fuel cells use a similar reaction between hydrogen and oxygen except a proton travels across the membrane from the hydrogen side to the oxygen side, so the reaction mechanism differs. This paper looks into those same iron based catalysts tested in an alkaline environment. The catalyst in particular is 1% iron in 1:1 Black Pearls 2000 : 1,10 phenanthroline. Those precursors are combined using a wet impregnation and then the result is ball milled. It then undergoes an argon pyrolysis at 1050oC and an ammonia pyrolysis at 950oC which are the final steps in the synthesis. The completed catalyst can then be washed in acid for 1 hour, 2 days, or 1 week to compare the effect of acid washing on different factors. The different catalysts are compared at each stage in the synthesis mainly by their onset potential, which is the voltage where it produces a current density of 0.1 mA/cm2. -
Advanced Ionomers & Meas for Alkaline Membrane Fuel Cells
Advanced Ionomers & MEAs for Alkaline Membrane Fuel Cells PI Bryan Pivovar National Renewable Energy Laboratory June 15, 2018 DOE Hydrogen and Fuel Cells Program 2018 Annual Merit Review and Peer Evaluation Meeting Project ID #FC147 This presentation does not contain any proprietary, confidential, or otherwise restricted information. Overview Timeline and Budget Barriers • Project start: October 2015 • Durability • Project end: March 2019 • Cost • % complete: ~ 70% • Performance • DOE Budget plan Partners – FY 2016 - 2018 $ 2,600k – Cost Share Percentage – 0% • LBNL – Adam Weber • ORNL/UTK – Tom Zawodzinski • Colorado School of Mines – Andy Herring • (in-kind) 3M – Mike Yandrasits NREL | 2 Relevance/Impact DOE (Preliminary) Milestones for AMFCs* • Q2, 2017: Develop anion-exchange membranes with an area specific resistance ≤ 0.1 ohm cm2, maintained for 500 hours during testing at 600 mA/cm2 at T >60 oC. • Q4, 2017: Demonstrate alkaline membrane fuel cell peak power performance > 600 mW/cm2 on 2 H2/O2 (maximum pressure of 1.5 atma) in MEA with a total loading of ≤ 0.125 mgPGM/cm . • Q2, 2019: Demonstrate alkaline membrane fuel cell initial performance of 0.6 V at 600 mA/cm2 on 2 H2/air (maximum pressure of 1.5 atma) in MEA a total loading of < 0.1 mgPGM/cm , and less than 10% voltage degradation over 2,000 hour hold test at 600 mA/cm2 at T>60 oC. Cell may be reconditioned during test to remove recoverable performance losses. • Q2, 2020: Develop non-PGM catalysts demonstrating alkaline membrane fuel cell peak power performance > 600 mW/cm2 under hydrogen/air (maximum pressure of 1.5 atma) in PGM-free MEA. -
Role of Diffuse Layer in Acidic and Alkaline Fuel Cells
Author's personal copy Electrochimica Acta 56 (2011) 4518–4525 Contents lists available at ScienceDirect Electrochimica Acta journal homepage: www.elsevier.com/locate/electacta Role of the diffuse layer in acidic and alkaline fuel cells Isaac Sprague, Prashanta Dutta ∗ School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164-2920, USA article info abstract Article history: A numerical model is developed to study electrolyte dependent kinetics in fuel cells. The model is based Received 17 December 2010 on the Poisson–Nernst–Planck (PNP) and generalized-Frumkin–Butler–Volmer (gFBV) equations, and is Received in revised form 13 February 2011 used to understand how the diffuse layer and ionic transport play a role in the performance difference Accepted 15 February 2011 between acidic and alkaline systems. The laminar flow fuel cell (LFFC) is used as the model fuel cell Available online 23 February 2011 architecture to allow for the appropriate comparison of equivalent acidic and alkaline systems. We study the overall cell performance and individual electrode polarizations of acidic and alkaline fuel cells for Keywords: both balanced and unbalanced electrode kinetics as well as in the presence of transport limitations. The Alkaline fuel cell Acidic electrolyte results predict cell behavior based on electrolyte composition that strongly correlates with observed Alkaline electrolyte experimental results from literature and provides insight into the fundamental cause of these results. Electric double layer Specifically, it is found that the working ion concentration at the reaction plane plays a significant role in Laminar flow fuel cell fuel cell performance including activation losses and the response to different kinetic rates at an individual electrode. -
Development of Power Generation by Durect Ethanol Fuel Cell
FUEL CELL SYSTEMS S. Basu New Delhi Department of Chemical Engineering Indian Institute of Technology Delhi INDIA e- Load Water 1. Fuel chamber 2. Oxidant chamber 1 4 2 3. Anode (Pt) 4. Electrolyte Fuel 3 5 Oxidant 5. Cathode (Pt/C) (H ) 2 O2/Air + - H2 2 H +2e (Anode) + - 2 H +1/2 O2 +2e H2O (Cathode) H2 + 1/2 O2 H2O (Overall) 9 Automobile 9 Efficient Power Generation 9 Distributed Power Gen. 9 Environmental Friendly 9 Portable Electronics Eqpt. Fuel Cell Families Phosphoric Acid Cathode Anode o H+ 220 C Solid Polymer Cathode Anode o o H+ 30 C- 80 C Alkaline Air Cathode - Anode Fuel 50 oC- 200 oC OH Molten Carbonates o Cathode = Anode 650 C CO3 Solid Oxides Cathode Anode o o O= 700 C – 1000 C Alkaline Fuel Cell ALKALINE FUEL CELL Alkaline electrolyte - - Anode H2 + 2OH Æ 2H2O + 2e - - Cathode 1/2O2 + H2O + 2e Æ 2OH Overall H2 + 1/2O2 Æ H2O + electrical Energy +heat Poisoning: - 2- CO2 +2OH (CO3) + H2O ¾ Depletion of KOH ¾ Poisoning of cathode surface with carbonates Myth ! 9Kordesch, K. et al., (1999), Intermittent Use of a Low-Cost Alkaline Fuel Cell-hybrid System for Electric Vehicles, J. Power Sources, Vol. 80, pp. 9McLean, G. F. et al. (2002) An assessment of alkaline fuel cell technology, Int. J. Hydrogen Energy 27 507 9Gülzow, E., and Schulze, M. (2003), Long-Term Operation of AFC Electrodes With CO2- Containing Gases, J. Power Sources, Polymer Electrolyte Membrane Fuel Cell (PEMFC) Hydrogen Fuel Cell Direct Alcohol Fuel Cell (DAFC) Fuel Processor Fuel Cleaning System Fuel Pure H2 Electricity Fuel Cell Direct Methanol Fuel Cell Direct Ethanol Fuel Cell (DMFC) (DEFC) Reduce CO adsorption on Pt at High Temp Higher power density at high temperature Easy breakage C-C bond in DEFC at High Temp.