Developing Markets for Natural Graphite by George C Hawley
Developing Markets for Natural Graphite By George C Hawley, President George C. Hawley & Associates Supermin Enterprises Geophil33@gmail.com 877-335-8923 Prepared for: IM Graphite Conference – Graphite December 6-7 19, 2011, London, UK
Biographical• George C Hawley is an international consultant, specializing in the development and marketing of value-added products based on industrial minerals.• His work in the industrial mineral sector goes back to 1970.• His education and experience are in chemistry, chemical engineering and polymers. He is a member of the US Society of Plastics Engineers• His background in graphite goes back to the 1950’s when he was Research, Development and Quality Assurance Chemist for Morgan Crucible Company, the world’s second largest synthetic graphite product maker.• Specific projects were nuclear, rocket nozzles, chemical, anodes, brushes, and friction materials.• He has been working on the development of Canadian graphite since 2000.• In the 1950’s, he also worked on R & D and Process Control of lead acid batteries for a division of Chloride/Exide group.• Specific projects were electrodes, separators and casings.
Abstract Natural graphite is undergoing a resurgence. Graphite has a unique range of properties including refractoriness, high dimensional stability, chemical inertness, high electrical and thermal conductivity The existing end uses remain strong.New uses are developing especially in energy –related markets. Paramount in these is the use in lithium ion battery anodes.
Nature of Graphite• Graphite - native carbon 3 covalent bonds at 120 degrees in a plane. (graphene)• • 4th bond forms electron gas below and above plane, spacing 0.34 nm. Electron gas is mobile = high electrical & thermal conductivity in plane • But much less perpendicular to plane.• •Similar anisotropy in thermal expansion and diamagnetism •• Natural form is flake. Layers slide on each other on film of air or water• • 2 crystal arrangements – slightly different properties•• Hexagonal graphite ( alpha) ABAB Rhombohedral ( beta) ABCABC• Alpha converts to Beta on pulverising Beta converts to Alpha above 1000 deg C•• Alpha graphite is semi-metallic Beta graphite is a semi-conductor.•• Natural flakes 70% alpha + 30% beta. Synthetic graphite is pure alpha graphite.
• Key Properties of Natural Graphite• Low electrical resistivity (especially in the plane) Low thermal expansion (negative in the plane)•• High specific heat High Thermal conductivity (especially in the plane)•• High melting point (3550 degrees Celsius) Excellent thermal shock resistance•• High refractoriness Low chemical reactivity (slowly oxidised)•• Low Porosity Hydrophobic & not wetted by molten metals & slags•• High Lubricity Low Hardness (less machine wear) High strength & stiffness•• Low Density (SG 2.2) ( compared to metals & non-metals) High diamagnetism•• Low neutrons & X-rays absorption High absorption of microwaves IR reflective • Intercalatable – expandable graphite and lithium ion batteries
GrapheneDefinition: Graphene is a one-atom-thick planar sheet of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice Thickness Graphene 0.335 nm human hair 100,000 nm Strength Breaking stress 130 GPa ( steel 0.4 GPa, at 7.8 g./cc) Stress to break 10 cm ribbon 1lb Resistivity, ohm/cm Graphene 1 x 10-6 silver 1.59 x 10-6 copper 1.68 x 10-6 silicon 6.4 Electron mobility,cm2/V.s Graphene 15,000 silicon 1,400 Absorption of white light 2.3% Requirement to replace 4 - 8 nm ITO in touch screens 6 - 12 tonnes Price – 100 g 12 nm thick “ graphene” $495
Developing markets The high price of oil and its products, shortages andenvironmental concerns with fossil fuels, will have a great effect on minerals demand. These changes are in the sectors of: Energy Sources Energy Storage Energy Control Copyright 2010- George C Hawley & Associates
Energy Sources • Nuclear • Solar• Wind/wave /tidal
Non -Nuclear Energy Sources Solar Energy Potential for graphene transparent electrically conductive layer Wind/Wave/Tidal Potential for composites based on partialsubstitution of graphene/ expanded graphite for carbon fibers in high strength/high stiffness composites.
Energy Storage Applications BatteriesLithium Ion Lithium Ion polymer Lithium bromide Fuel Cell Flow Battery Bipolar Plates Supercapacitors
Energy Control Applications Building Envelope Phase Change Material encapsulation (expanded) Polystyrene foam insulation (micronised) Wall & ceiling heating elements (expanded/graphene) Fire protection (expandable)Fire stopping/barriers Polyurethane foam upholstery ConductivityHeat sinks – computer chips(expanded) electrostatic painting (micronised & expanded) Oil & Solvent Spill Management ( Expanded) Resistive De-icing ( expanded/graphene) Parking garages Aircraft Power lines Composites ( expanded/graphene) Aircraft Wind Turbine Automotive Sporting Goods
Nuclear Energy - Pebble Reactors Graphite content in the graphite matrix of Triso pebbles is 25 - 65% natural, balance synthetic. Calculated natural graphite needed for 110 MWe pebble reactor For commissioning 100 tonnes; Annual pebble replacement 19 – 35 tonnes Copyright 2010- George C Hawley & Associates
PBMR vessel, turbines, and generator Copyright 2010- George C Hawley & Associates
Nuclear Plants – Existing & Future China China Russia Russia Japan Japan India India World WorldStatus plants MWe plants MWe plants Mwe Plants Mwe plants MweJan 2007Operating 11 8,587 31 21.743 55 47,577 17 3,779 439 372,059Building 5 4,540 7 4,920 2 2,285 6 2,976 34 27,798Planned 30 32,000 8 9,600 11 14,945 10 8,560 93 100,595Proposed 86 68,000 20 18,200 1 1,100 9 4,800 222 193,095Total 121 104,540 35 32,720 14 18,330 25 16,336 349 321,488 2011 China – 14 operating, 26 in construction – 2 PBMR. Sources: Reactor data: WNA to 14/01/08.IAEA- for nuclear electricity production & percentage of electricity (% e) Copyright 2010- George C Hawley & Associates
Lithium Ion Batteries (LIB)• Rechargeable (secondary) lithium ion batteries are rapidly replacing other types because of their high voltage, high capacity, longevity, and light weight.• 67% of all portable secondary batteries in Japan are LIB.• They are now used in cell phones, laptops and power tools.• They are a common, but expensive, alternative to lead acid batteries used in electric bikes and are starting to be used in electric cars and trucks.• Because of high petroleum prices and global warming due to carbon emissions from internal combustion engines, the future of LIB is bright.• In view of the projected growth, availability of components is key.
Lithium Batteries 101• Lithium ion batteries consist of two electrodes - a cathode of some lithium- containing compound, and an anode which is most commonly graphite based.• Both active materials are mixed with polymer and coated onto metallic foil which carries the electrons to the exterior.• These electrodes are insulated from each other by a permeable polymeric separator.• The ions move through an organic electrolyte. This is reactive with the anode graphite, causing loss in capacity (irreversible capacity), but has some benefits. A graphite anode must be coated to optimize this.• Lithium metal is the ideal anode, but it is highly reactive with water and air, and can catch fire. The problem is overcome by using an anode of a substance that can intercalate lithium ions, which react reversibly with it.
Desirable Characteristics of LIB Anode Materials• High reversible capacity• Low Irreversible capacity (due to reaction with electrolyte)• Good electrical and thermal conductivity• Dimensional stability• Long life• Easy processing• Non-reactive with other components – safety• LOW COST (especially for automotive applications)
Availability of Components• Lithium is plentiful.• Graphite is the least expensive of intercalating substances. There are many others. But all have disadvantages – low voltage, high expansion, poor life, poor conductivity, and high cost.• Synthetic graphite is satisfactory, and has a large source in petroleum coke. But natural graphite has lower cost and higher capacity.• The weight of graphite required is theoretically 10.4 times that of lithium, but is closer to 13 X due to inefficiencies. It works out to be about 2 x LCE.• China produces 73% of the world’s natural graphite, Canada only 2.3%.• China has applied export licences, export duties and VAT on graphite exports increasing the cost at mine site by 50%. This and scarcity has increased graphite prices by a factor 3.5 over historic levels.• China has announced intention to be the world leader in electric vehicles.• The largest use of graphite is in refractories for the steel industry. So growth of LIB will compete with the steel industry which has been growing in China at the rate of 8- 12 % annually.
New Possibilities for Graphite Anodes Capacity, mAh/g LIC6 372 Li C2.33 900 LiC1.0 2238
New Possibilities for Graphite Anodes (2) Li+ only intercalates via edges of graphiteTime to charge depends on the velocity of the lithium ions Solution:perforate the graphite to allow entrance of the ions Result: charging time reduces 10 x
New Possibilities for Lithium Ion Batteries Lithium bromide cellsLithium and bromine both intercalate in graphite Bromine can be displaced by heat at 80 0C + LiBr battery can be recharged by waste heat
Cost of Lithium Ion Batteries for Vehicles ANL May 2000 High Energy CellMaterial Price/kg g/cell % Cell costCathode 55 1,408 48.8Electrolyte 60 618 23.4Graphite 30 563.6 10.7Separator 180 60.5 6.9 High Power CellMaterial Price/kg g/cell % Cell costCathode 55 64.8 28.2Electrolyte 60 44 20.9Graphite 30 12.7 3.0Separator 180 16.4 23.3
Selected Properties of Lithium Ion Battery Anode Materials Thermal Density Resistivity, Material Conductivity g/cc. Ohm.m W/m.K 470 10-7-10-6 in basal plane Graphite 2.26 25 10-5-10-2 perpendicular Silicon 2.40 149 6.4 x 10-2Germanium 5.36 58 4.6 x 10-1 Lithium 0.53 84.8 9.28 x 10-3Note: Lower electrical resistivity means greater conductivity
Expansion of Lithium Ion Battery Anode Materials on Charging and Discharging Graphite +/- 10% Silicon +/- 300% Germanium +/- 370% Compare with Ice /Water Freeze Thaw +/- 9.97%
Comparison of Typical Carbon Capacities (Enerdel)Material Initial Reversible Irreversible % First capacity, capacity, capacity, Cycle mAh.g mAh.g mAh.g EfficiencyGraphite 390 360 30 92Hard 480 370 90 77CarbonSoft 275 235 40 85Carbon Note: Non –graphitizable hard carbon is made from precursors that char as they are pyrolized.
Chinese Graphite for Lithium Ion Batteries Particle Tap Surface Discharge size, Fixed Density, Area Capacity D50 Carbon, % g/cc m 2 /g. mAh/g microns Natural 12 – 25 >= 99.95 >= 1.0 3.5 – 7.5 360-370 MCMB 8 - 16 99.9 -99.96 1.30 – 1.42 1.0 – 2.5 320-340Notes:1. Natural graphite manufacturers micronize, process into potato shape and purify their concentrates. Battery manufacturers add proprietary coatings to reduce electrolyte reaction. Spacing between planes – 0.335 nanometers.2. MCMB = MesoCarbonMicroBeads, Made by controlled carbonisation of pitch from which low molecular weight fractions have been volatilised. Then the residues are extracted by solvent. The product is then graphitised. Known as “Soft Carbon” Spacing between planes – 0.375 nanometers.
Notes:1. All products except A12 are based on petroleum coke.2. CPreme coat the coke particles to make them rounder.3. ConocoPhillips produces annually 5 million out of 80 million tons coke world total.4. A12 is based on natural graphite. Its capacity is higher than the coke-based anode graphite.
Positive electrodes Electrode Av. potential Specific capacity, Specific energy, material difference, volt mA.h/g kW.h/kg LiCoO2 3.7 140 0.518 LiMn2O4 4.0 100 0.400 LiFePO4 3.3 180 0.495Li3V2 (PO4) 3 3.0 – 4.2 131.2 n.a.
Price of Lithium Ion Battery Anode Materials US$/kg World Production tonnesNatural Graphite, 99.95% 10 - 30 2000 – 3000total natural graphite 1.1-1.6 million(potential demand for LIB 0.5 – 1.0 million)Synthetic Graphite, 99.99% 15 - 60 84,500Silicon, 99.99% 65 31,800(total silicon) (780,000)Germanium, 940-1425 120
World Vehicle Production, 2010Region Million unitsWorld 77.86China 18.26USA + Canada + Mexico 12.17Japan 9.61Germany 5.91S. Korea 4.27India 3.54UK 1. 39Forecast 2015 ( PricewaterhouseCoopers ) 97
Estimation of Graphite Demand for Vehicular Lithium Ion Battery Anodes Cumulative Lithium Demand from 2010 to 2100 for Electric Vehicles Kg Lithium per vehicleHybrid EV Plug In Hybrid EV Battery EV0.068-0.091 1.48-2.28 5.13-7.70 Gruber et al., Global Lithium Availability and Electric Vehicles, Journal of Industrial Ecology, July 2011 Calculated Equivalent Demand for anode graphite * tonnes per million vehicles710 – 950 15,390 -23,710 53,350-80,080 * Assumes 100% efficiency.
Electric Local Delivery Vehicles Fedex 43 EV Purolator 955 HEV UPS 128 EV ( out of 2,200 alternative energy vehicles including HEV, biodiesel, LNG, CNG and propane USPS (proposed) 20,000 EV LA Airport eBus -12 EV Lifetime fuel savings $0.5 million School buses city buses submarines
Conclusions1. Natural graphite is finding new markets mainly related to energy .2. It is the best choice now available as a precursor for lithium ion battery anodes for EV.3. It is abundant in nature and has the lowest cost.4. It has high electrical and thermal conductivity.5. Its characteristics and performance are well known.6. For LIB anodes, it must be micronized, spheronized, purified and coated7. Synthetic graphite makes an excellent anode. It is already fairly pure and rounded.8. It is abundant as a by-product of refining of certain petroleum products.9. But it has lower capacity, due to its internal structure.10. It is costly since coke has to be graphitized at 2600-3300 0 C