CARBON Electrochemical ond Physicochemicol Properties KIM KINOSHITA Lawrence Berkeley Laboratory Berkeley, California A Wiley-Interscience Publicotion JOHN WILEY & SONS New York / Chichester / Brisbane / Toronto / Singapore
INTRODUCTION 1.1 Background, 1 1.2 Manufacture of Carbons for Electrochemical Applications, 3 1.2.1 Carbon Blacks, 1.2.2 Active Carbon, 1.2.3 Graphite, 10 1.2.4 Glassy Carbon, 1.2.5 Carbon Fibers, 3 10 13 14 1.2.6 Carbon Manufacturers, References, 17 17 PHYSICAL PROPERTIES 20 2.1 Crystallographic Structure, 22 2.1.1 Electron Microscopy, 23 2.1.2 X-Ray Diffraction Analysis, 31 2.2 Surface Area and Porosity of Carbon Blacks, 35 2.2.1 Electron Microscopy, 35 2.2.2 X-Ray Diffraction, 36 2.2.3 Gas-Phase Adsorption, 37 2.2.4 Liquid-Phase Adsorption, 41 2.3 Morphology of Carbon-Black Aggregates, 43 2.3.1 DBP Absorption Method, 45 2.3.2 Electron-Microscopy Analysis, 45 2.3.3 Comparison of Data Obtained by DBP Absorption and Electron Microscopy, 48 ix
X 2.3.4 Imaging Analysis and Centrifugation Methods, 52 2.3.5 Tinting Strength, 53 2.4 Effect of Heat Treatment, 56 2.4.1 Crystallite Parameters, 57 2.4.2 Surface Area, Density, and Porosity, 61 2.4.3 Surface Microstructure, 64 2.4.4 Catalytic Graphitization, 67 2.5 Electrical Properties, 68 2.5.1 Effect of Crystallographic Structure and Orientation, 71 2.5.2 Electrical Resistivity of Carbon Particles, 72 2.5.3 Electrical Resistivity of Carbon-Elastomer Composites, 75 References, 79 3 CHEMICAL AND SURFACE PROPERTIES 86 3.1 Formation of Surface Groups, 86 3.1.1 Carbon-Oxygen Complexes, 87 3.1.2 Carbon-Hydrogen Complexes, 88 3.1.3 Carbon-Nitrogen Complexes, 90 3.1.4 Carbon-Sulfur Complexes, 90 3.1.5 Carbon-Halogen Complexes, 91 3.2 Surface Groups and Carbon Microstructure, 93 3.2.1 Chemical Analysis, 93 3.2.2 Spectroscopic Analysis, 105 3.2.3 Thermal Analysis, 131 3.3 Surface Phenomena, 139 3.3.1 Liquid-Phase Adsorption, 139 3.3.2 Wetting Studies, 146 3.3.3 Surface Polarity, 157 3.3.4 Work Function, 159 3.3.5 Zeta Potential, 160 3.3.6 Surface Decoration, 164 References, 166 4 CHEMICAL REACTIONS 174 4.1 Gas-Phase Reactions, 174 4.1.1 Oxygen Chemisorption, 175 4.1.2 Reactions with Oxygen- and Hydrogen-Containing Gases, 177 4.2 Liquid-Phase Reactions, 195 4.2.1 Oxidation by Ozone, 195 4.2.2 Oxidation by Dichromate, 197 4.2.3 Oxidation by Acids, 199
XI 4.3 Formation of Intcrcalation Compounds, 201 4.3.1 Graphite Fluorides, 204 4.3.2 Graphite Oxides, 208 4.3.3 Acid Compounds, 211 4.3.4 Halogen Compounds, 214 4.3.5 Alkali Compounds, 216 4.3.6 Molecular Compounds, 217 References, 219 5 CHARACTERISTICS AND PROPERTIES OF CARBON ELECTRODES 226 5.1 Nonporous Structures, 228 5.1.1 Graphite, 228 5.1.2 Glassy Carbon, 230 5.1.3 Carbon Composites, 231 5.1.4 Carbon Fiber, 238 5.1.5 Chemically Modified Electrodes, 239 5.1.6 Electrode Activation, 251 5.2 Porous Structures, 258 5.2.1 Flooded Electrodes, 258 5.2.2 Gas-Diffusion Electrodes, 262 5.3 Intercalated Graphite Structures, 274 5.3.1 Intercalation of Anions, 275 5.3.2 Intercalation ofcations, 279 5.3.3 Covalent-Bonded Intercalation Compounds, 281 References, 284 6 ELECTROCHEMICAL DEHAVIOR OF CARBON 293 6.1 Electrochemical Analysis, 293 6.1.1 Double-Layer Capacitance, 293 6.1.2 Potentiometrie Response, 301 6.1.3 Potentiodynamic Investigation of Surface Groups, 306 6.2 Electrochemical Oxidation of Carbon Blacks and Graphites, 316 6.2.1 Acid Electrolytes, 317 6.2.2 Alkaline Electrolytes, 334 6.2.3 Chloride-Containing Electrolytes, 337 6.2.4 Flow-Battery Electrolytes, 350 6.3 Electrochemical Reactivity of Coal, 352 6.3.1 Electrochemical Oxidation, 352 6.3.2 Electrochemical Reduction, 359 6.4 Electrocatalysis on Carbon, 360 6.4.1 Oxygen Reduction-Evolution, 360 6.4.2 Decomposition of Hydrogen Peroxide, 369
xii 6.4.3 Hydrogen Oxidation/Evolution, 372 6.4.4 Reaction of Halogens, 374 6.4.5 Other Redox Couples, 377 References, 379 7 APPLICATION OF CARDON IN ELECTROCHEMICAL SYSTEMS 386 7.1 Preparation of Electrocatalysts Supported on Carbon, 388 7.1.1 Impregnation, 390 7.1.2 Ion Exchange, 391 7.1.3 Adsorption, 393 7.1.4 Organic Macrocyclcs, 393 7.2 Fuel Cells, 396 7.2.1 Electrodes, 397 7.2.2 Bipolar Electrode Separators, 401 7.3 Batteries, 403 7.3.1 Conductive Matrix, 403 7.3.2 Solid and Porous Electrode Structures for Flow Batteries, 411 7.3.3 Polymer-Bonded Carbon-Black Electrodes, 419 7.3.4 Intercalated Graphite Electrodes, 427 7.4 Industrial Electrochemistry, 430 7.4.1 Reactions Involving Inorganic Compounds, 430 7.4.2 Electroorganic Synthesis, 434 7.4.3 Electrochemical Treatment of Solutions, 438 7.4.4 Carbon Capacitors, 441 7.5 Electroanalytical Chemistry, 443 7.5.1 Liquid Chromatography with Electrochemical Detection, 443 7.5.2 Sensor Electrodes for Inorganic and Organic Species, 445 7.5.3 In Vivo Measurements, 449 References, 453 8 CONCLUDING REMARKS 469 8.1 Physicochemical Properties, 469 8.2 Electrochemical Properties and Applications, 470 8.3 Research on Carbons for Electrochemistry, 472 8.3.1 Surface Properties, 472 8.3.2 Structure-Related Properties, 473 8.3.3 Modification of Carbon Surface, 473 8.3.4 Applications in Electrochemistry, 474
XIII APPENDIX 476 A.l Humic Acid, 476 A.2 Coal, 477 A.3 Fuel-Cell Patents, 477 A.4 Recent Patents on Carbon/Graphite in Batteries, 490 INDEX 515