Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
Natural Graphite versus Synthetic, Silicon and Others in Lithium Ion
Battery Anodes
George C Hawley President
George C Hawley & Associates [email protected]
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 99.95+%. 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.
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.
Processing of Natural Graphite for Use in Lithium Ion Cell Anodes
Mining
Flotation
Drying
Classification
Pulverisation 10 – 50 microns
Spheronisation
Purification 99.9-99.99%
Coating
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
Lithium ion versus other secondary cells
Voltage, volts Specific Energy, MJ/kg
Lithium ion 3.6 0.46 NiMH 1.2 0.36 NiCd 1.2 0.14 Lead acid 2.1 0.14
Cathode Material
Theoretical
Capacity
mAhr/g
Voltage
versus
Lithium
Expansion
% Safety Toxicity Cost
Cobalt Oxide 273 3.6 Poor Med High
NiCo Oxide 240 3.5 Good Med Med
Layered Mn Oxide 285 3.8 Very
Good Low Low
Iron Phosphate 170 3.2 Very
Good Low Low
Lithium Sulfide 1600 2.3 Poor Low Low
Comparison of Specific Capacity of Cathodes and Anodes
Lithium Anode Materials
Material
Theoretical
Capacity ,
mAhr/g
Expansion on
charging,%
Resistivity,
Ohm.m Cost,$/kg
Lithium metal 3860 na 9.28 x 10-8 ?
Graphite -
basal plane 372 10 2.5 – 5.0 x 10-6
Natural 10 Synthetic 20-40
Graphite –
Perpendicular
to basal plane
372 10 3.0 x 10-3 Natural 10
Synthetic 20-40
Silicon 4200 410 640 53
Tin 1500 260 1.09 x 10-7 20.40
Germanium 1600 300-400 0.46 1700
Aluminum 2234 90 2.82 x 10 -8 2.64
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 1,408.6 77.47 48.8 64.8 3.56 28.2
Separator 180 60.5 10.89 6.9 16.4 2.95 23.3
Electrolyte 60 618.0 37.08 23.4 44.0 2.64 20.0
Graphite 30 563.6 16.91 10.7 12.7 0.38 3.0
Can & Vent 291.0 3.20 2.0 70.0 0.77 6.1
Binder 45 162.6 7.32 4.6 8.8 0.40 3.1
Copper 15 151.9 2.28 1.4 41.6 0.62 4.9
Aluminum 20 63.0 1.26 0.8 19.4 0.39 3.1
Carbon 20 46.4 0.93 0.6 2.2 0.04 0.3
Other 20 67.1 1.34 0.8 44.8 0.90 7.1
Total 3,432.7 158.68 100 324.7 12.66 100
Material Costs for Lithium Ion Cells (Argonne National Lab. ESD-2 May 2000)
Rough Estimate of 18650 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 0.15-0.25
Direct Labor 0.18-0.24
Total Manufacturing Cost 1.70 +/-
Targray’s Portfolio of Graphite Anode Active Battery Materials.
Product Series Characteristics
Discharge
Capacity
First
Efficiency
Design
Capacity/Fu
ll Cell
D50 BET Tap Density Compresse
d Density Applicable
System
mAh/g % mAh/g um m2/g g/cm3 g/cm3
High
performance
anode material
Compound natural
graphite, high
capacity, high first
efficiency, good
machinability
PGPT100 365.2 95.1 345-355 18-21 1.68 ≥1.15 1.60-1.65 SBR/PVDF
High performance
artificial graphite,
high capacity, high
rate capability,
good cycle/ safety
performance
PGPT200 338.52 94.5 325-335 23-27 0.92 ≥1.08 1.55-1.60 SBR/PVDF
PGPT202 340.3 94.5 325-335 13-17 2 ≥0.95 1.45-1.55 SBR/PVDF
Anode material for
power cell
High rate
capability material
PGPT300 343.1 93.9 325-330 20-24 1.68 ≥1.05 1.40-1.45 SBR/PVDF
PGPT301 343.2 93 320-325 13-17 2.09 ≥0.90 1.45-1.48 SBR/PVDF
Capacity-type
anode material for
power cell
PGPT350 327 90.2 295-305 22-26 4.8 ≥1.15 1.50-1.55 SBR/PVDF
PGPT351 342.4 90.8 320.33 21-25 5.2 ≥0.90 1.55-1.60 SBR/PVDF
Anode material
Modified natural
graphite, high
capacity, good
machinability
PGPT400 361.6 94.2 340-345 18-20 1.86 ≥1.10 1.58-1.62 SBR/PVDF
PGPT405 >355.3 >92.1 342-350 10.0-14.0 <3.0 >1.1 1.55-1.60 SBR/PVDF
Graphite
conductive
additives
PGPT501 350 83 3 9 20 10.8 0.4
Synthetic versus Natural Graphite as Anode
http://www.cpreme.com/EN/Pages/index.aspx
CPreme Product Selection Chart
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.
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.