Natural Graphite versus Synthetic, Silicon and Others in Lithium Ion Battery Anodes

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1 Natural Graphite versus Synthetic, Silicon and Others in Lithium Ion Battery Anodes George C Hawley President George C Hawley & Associates Supermin123@hotmail.ca

2 Biography George C. Hawley & Associates was established in 1971 as a consulting practice for industrial mineral producers and consumers, world -wide. He was R&D/QC Chemist at Morgan Crucible (Morganite Carbon) researching polymer impregnated graphite brushes, electrodes, friction materials, sealing rings, nuclear graphite, rocket nozzles and chemical graphite. As R&D/QC Chemist at the Chloride Group, he worked on high porosity plastic separators, cases, and anodes and cathodes for lead-acid batteries. Since 2002, he has returned to graphite R & D and Market Research and Development, as a consultant to Quinto Mining, and Industrial Minerals Inc. (now Northern Graphite Corporation). Achievements have been the development of lithium-ion anode grade products based on NGC concentrate, including novel purification technology to increase purity of this and flake graphite to %. G.C. Hawley has published over 50 papers on technical and marketing topics of industrial minerals and mineral-based products, including chapters in 3 handbooks.

3 Abstract Lithium battery production continues to grow at about 10% per year, based on their unrivalled properties. Lithium metal would be the best anode and it is used in primary (non-rechargeable) cells. But lithium metal reacts violently with both air and water and grows dendrites which tend to short out the electrodes The solution is to have lithium present in the anode in the form of non-explosive ions. These ions are intercalated between the layers of the graphite crystal. Both synthetic and natural graphite fine powders are use in the anodes. These two types compete actively in price and performance. The specific capacity of graphite is low in comparison with metals that can take up lithium by alloying, in amounts up to ten times more. But all these metals silicon, germanium, tin etc.- have severe problems. These include large expansion on alloying up to 410% for silicon; restricted life span; complicated production methods; high cost and uncertain safety.

4 Processing of Natural Graphite for Use in Lithium Ion Cell Anodes Mining Flotation Drying Classification Pulverisation microns Spheronisation Purification % Coating

5 Synthetic graphite from needle coke

6 Production of Synthetic Graphite for Use in Lithium Ion Cell Anodes Extraction Oil from Ground (Wells or oil sands/shale) Refining of oil Recovery of still bottoms Calcination in coking drum (450 deg C) Graphitization to 99.9% (2800+ deg C) Or 99.98% (3100 degrees C) Pulverisation (10-50 microns) Coating

7 Lithium ion versus other secondary cells Voltage, volts Specific Energy, MJ/kg Lithium ion NiMH NiCd Lead acid

8 Comparison of Specific Capacity of Cathodes and Anodes Cathode Material Theoretical Capacity mahr/g Voltage versus Lithium Expansion % Safety Toxicity Cost Cobalt Oxide Poor Med High NiCo Oxide Good Med Med Layered Mn Oxide Very Good Low Low Iron Phosphate Very Good Low Low Lithium Sulfide Poor Low Low

9 Material Theoretical Capacity, mahr/g Lithium Anode Materials Expansion on charging,% Resistivity, Ohm.m Cost,$/kg Lithium metal 3860 na 9.28 x 10-8? Graphite - Natural x 10-6 basal plane Synthetic Graphite Perpendicular to basal plane x 10-3 Natural 10 Synthetic Silicon Tin x Germanium Aluminum x

10 Comparison of Cathode and Anode Materials

11 Material Costs for Lithium Ion Cells (Argonne National Lab. ESD-2 May 2000) High Energy Cell 100 A- hr High Power Cell 10 A-hr Material Price $/kg Qty, g. Cost/cell $ % of cost Qty, g. Cost/cell $ % of cost Cathode 55 1, Separator Electrolyte Graphite Can & Vent Binder Copper Aluminum Carbon Other Total 3,

12 Rough Estimate of Cell Manufacturing Costs (Argonne National Lab. ESD-2 May 2000) Item Cost,$ Materials Lithium cobaltate cathode 0.62 Separator 0.14 Electrolyte 0.30 Anode 0.24 Materials sub total 1.28 Overhead Direct Labor Total Manufacturing Cost /-

13 Targray s Portfolio of Graphite Anode Active Battery Materials. Product Series High performance anode material Anode material for power cell Anode material Characteristics Compound natural graphite, high capacity, high first efficiency, good machinability High performance artificial graphite, high capacity, high rate capability, good cycle/ safety performance High rate capability material Capacity-type anode material for power cell Modified natural graphite, high capacity, good machinability Graphite conductive additives Synthetic versus Natural Graphite as Anode Discharge Capacity First Efficiency Design Capacity/Fu ll Cell D 50 BET Tap Density Compresse d Density mah/g % mah/g um m 2 /g g/cm 3 g/cm 3 Applicable System PGPT SBR/PVDF PGPT SBR/PVDF PGPT SBR/PVDF PGPT SBR/PVDF PGPT SBR/PVDF PGPT SBR/PVDF PGPT SBR/PVDF PGPT SBR/PVDF PGPT405 >355.3 > <3.0 > SBR/PVDF PGPT

14 CPreme Product Selection Chart

15 Proposed Graphite Substitutes The theoretical specific and volumetric capacities of various fully lithiated phases of electrochemically active metal elements. The volumetric capacity is calculated using the fully lithiated volume. Notice that graphite compares poorly with all the alloying metals.

16 Proposed Graphite Substitutes In all this work, the effectiveness of the metal is diluted by the necessity for a carbon-based carrier and for the expansion chambers necessary to allow the metal to expand. The photomicrograph shows one such structure. Note the high void content.

17 Conclusions Graphite is the only viable anode material for lithium ion cells. Whether natural or synthetic is used will depend mainly on price. All alloying metals are too expensive and expansive and may not be available in sufficient supply to meet demands if EV production takes off as estimated