Advanced Energy Storage and the Importance of Graphite ...€¦ · •540,000 EVs sold in US in...
Transcript of Advanced Energy Storage and the Importance of Graphite ...€¦ · •540,000 EVs sold in US in...
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July 19, 2017 1
Advanced Energy Storage and the Importance of Graphite
Anode MaterialsDr. John C. Burns – CEO Novonix, Canada
Dr. Edward R. Buiel – CEO PUREgraphite, USA
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• LIB Raw Materials+ How much of what is in each cell?
• Battery Safety
• Natural Graphite Quality for LIBs+ Is larger flake or small flake battery?
+ Purity of the resource and contamination?
+ Is one deposit better than another?
• LIB Life Predictions+ Is Graphite important or just along for the ride?
Overview
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LIB Raw Materials
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Raw Materials in LIBs
• 40-60% cost is raw materials
• Cathode = 16%
• Anode = 6%
• Data from Christophe Pillot (AvicenneEnergy - 2016)
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Cathode Materials in LIBs
• Li[Ni0.6Mn0.2Co0.2]O2 is taking LCO market share in portable electronics and is primarily used in EVs
+ Elemental metals mass breakdown:➢ Li: 11%➢ Ni: 54%➢ Mn: 17%➢ Co: 18%
• Li[Ni0.8Co0.15Al0.05]O2 is used by Panasonic in Tesla cells+ Elemental metals mass breakdown:
➢ Li: 11%➢ Ni: 78%➢ Co: 9%➢ Al: 2%
• Data from Christophe Pillot (Avicenne Energy - 2016)
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Anode Materials in LIBs
• Natural graphite and artificial graphite are primary materials
• Natural is typically cheaper and used in lower end applications.
• Market for artificial graphite likely to grow with EV demand.
• Data from Christophe Pillot (Avicenne Energy -2016)
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Total Material Breakdown
• Estimates for NCA/Gr 18650 cell:+ Cell weight: 50g
+ Cathode active weight: 20g➢ Lithium: 1.4g
➢ Nickel: 10.4g
➢ Cobalt: 1.2g
➢ Aluminum: 0.2g
+ Anode active weight: 10g➢ Graphite: 10g
+ Electrolyte: 5g➢ Lithium: 0.35g
+ Inactive material (foils, separator, housing): 15g
“Our cells should be called Nickel-Graphite, because primarily the cathode is nickel and the anode side is graphite with silicon oxide… [there’s] a bit of lithium in there but its like the salt on the salad”– Elon Musk (June 2016)
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Battery Requirements
• Different applications have very different demands for lifetime and power.
• Cells are designed with different materials to meet these demands at different price points.
Material Demand Lifetime Requirements Cost
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Battery Safety
• Primary concern of major cell suppliers to consumer industries
• When built well, lithium-ion cells can be very safe
• When built “cheap”, lithium-ion cells can be very dangerous
Hoverboards and e-cigarettes have a low quality cells in them and have experienced a high
degree of failures
~100,000 Tesla vehicles on the road~8,000 cells per vehicle
~800,000,000 cells< 50 battery safety incidents
~50 part per billion
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Battery vs Gasoline Safety• 2003-2007 – 287,000 vehicle fires per year and in 2015 264M gas cars were on the road:
+ 1 fire in ~1,000 vehicles
• 540,000 EVs sold in US in 2016, < 50 incidents+ 1 fire in >10,000 vehicles
• Gasoline fires are explosive, lithium ion fires are harder to start and they do not propagate quickly with properly built battery packs.
Gasoline car fire
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Graphite Processing
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Conventional Natural Graphite Process
• Chinese yield is only 30%
• Yield cost up to $1,000/ton
• Difficult to use HCl/HF in the US
• Needs improvement in consistency
• Significant residual impurities
• Requires calcination
• Not environmentally friendly
Spheronizing
HCl/HF Purification
Pitch Coating
Calcination
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Natural Graphite Quality for LIBs
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Natural Graphite Resources
• Large reserves of graphite with companies actively working to develop the resource
• Coulometrics has worked with about a dozen sources all over the world to sample and test the flake
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Rigorous Flake Concentrate Analysis
• FLAKE ANALYSIS TESTING:
• Sieve samples to sizes shown in Table below.+ +50, 50x100, 100x200, 200x400, 400x635, -635 mesh + Measure masses to get flake size distribution (Table 1)+ Tap Density and LOI (Table 2)+ Measure BET (Table 3)
• Grind samples to -635 mesh+ Repeat BET+ XRD + EChem
➢ Build and test coin cells
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G16-0114Natural Graphite SampleSieve Analysis
Coulometrics Control #
Flake Size(mesh)
Particle Size(mm)
Mass in Sieve(g)
Size Fraction(%)
G16-0114
+50 0.300 0 0%
50x100 0.300-0.150 0 0%
100x200 0.150-0.075 7.66 3.4%
200x400 0.074-0.037 56.76 25.4%
400x635 0.037-0.020 98.98 44.2%
-635 0.020 60.41 27.0%
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G16-0114Natural Graphite SampleTap & Ash Analysis
ID#Flake Size
(mesh)Tap Density
(g/cc)
LOI – Ash Content (% carbon)
Sample 1 Sample 2 Sample 3 Average
G16-0114
As Received 0.53 96.37 96.43 96.49 96.43
+50 No material after sieving
50x100 No material after sieving
100x200 0.48 97.79 97.81 N/A 97.80
200x400 0.45 97.71 97.34 97.53 97.53
400x635 0.41 96.95 96.91 97.00 96.95
-635 0.40 94.26 93.24 94.48 93.99
Fine material concentrates impurities
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G16-0114GSP Ore, Graphite ConcentrateBET Analysis
ID#Flake Size
(mesh)
BET SA (As Received) BET SA (Ground to -635)
Ads.(m2/g)
Des.(m2/g)
Avg.(m2/g)
Ads.(m2/g)
Des.(m2/g)
Avg.(m2/g)
G16-0114
As Received 5.40 5.32 5.36 5.71 6.37 6.04
+50 Not enough material after sieving
50x100 Not enough material after sieving
100x200 3.39 3.41 3.40 6.67 6.43 6.55
200x400 4.11 4.18 4.15 5.94 6.08 6.01
400x635 5.08 5.07 5.08 7.04 6.86 6.95
-635 6.29 6.36 6.33 N/A N/A N/A
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PURITY?
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G16-0114GSP Ore, Graphite ConcentratePIXE Analysis
• Significant Impurities including:+ Al, S, Fe, and Si: 2400 - 4330ppm
➢ S (4560ppm)
➢ Si (7690ppm)
➢ Fe (2400 ppm)
➢ Al (3840ppm)
+ Smaller amounts of Na, Mg, Cl, K, Ca, Ti, Cr, Mn, Ni, Cu, Zn, Ga, As, Br, Rb, Zr, Mo….
Carbon ID Description Na Mg Al Si P S Cl K Ca Sc Ti V Cr Mn Fe Co Ni Cu
G16-0114 Graphite Corp 367 327 3840 7690 4560 62 976 167 156 37 6 2400 21 107
Zn Ga Ge As Se Br Rb Sr Y Zr Nb Mo Tc Rh Pd Ag Cd In Sn Sb Te I Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb
10 1 3 5 10 8 36
Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Th UTotal -ppm
20789
ID#
LOI – Ash Content (% carbon)
Sample 1
Sample 2
Sample 3
Average
G16-0114 96.70 96.78 96.74 96.74
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G16-0159Graphitized/Purified GSP OrePIXE Analysis
• Significant Impurities including:+ Al, Si, and Mo : 15 - 50ppm
+ Fe <10ppm
Carbon ID Description Na Mg Al Si P S Cl K Ca Sc Ti V Cr Mn Fe Co Ni Cu
G16-0159 Graphite Corp PF 50 22 8 5 1.8
Zn Ga Ge As Se Br Rb Sr Y Zr Nb Mo Tc Rh Pd Ag Cd In Sn Sb Te I Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb
15
Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Th UTotal -ppm
101.8
ID#
LOI – Ash Content (% carbon)
Sample 1
Sample 2
Sample 3
Average
G16-0159 99.99 100.00 99.99 99.99
Natural Graphite will NEVER EVER EVER not need to be purified….
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Electrochemistry?
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G16-0114: As ReceivedElectrode Preparation
• Electrode Mixing Information:+ Active material (G16-0114): 2.54g
+ Conductive carbon (SFG-6L): 0.056g
+ Binder (Kynar HSV900/NMP): 6.0%
• Electrode Properties+ Active mass: 92.0%
+ Loading: 13.76 mg/cm2
+ Calendered Density: 1.700 g/cc
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G16-0114: As Received1M LiPF6 in EC/DEC (1:1) Additives: NoneElectrochemical Data
• C/20 cycling+ Rev. Cap
➢ 364 - 368 mAh/g
+ Irrev. Cap.➢ 47.9 - 49.9 mAh/g
+ First cycle efficiency➢ 87.1 - 88.1%
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G16-0114: 100x200 Mesh1M LiPF6 in EC/DEC (1:1) Additives: NoneElectrochemical Data
• C/20 cycling+ Rev. Cap
➢ 364 - 366 mAh/g
+ Irrev. Cap.➢ 42.4 - 46.2 mAh/g
+ First cycle efficiency➢ 88.4 - 88.6%
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G16-0114: 200x400 Mesh1M LiPF6 in EC/DEC (1:1) Additives: NoneElectrochemical Data
• C/20 cycling+ Rev. Cap
➢ 374 - 375 mAh/g
+ Irrev. Cap.➢ 48.3 - 50.1 mAh/g
+ First cycle efficiency➢ 88.0%
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G16-0114: 400x635 Mesh1M LiPF6 in EC/DEC (1:1) Additives: NoneElectrochemical Data
• C/20 cycling+ Rev. Cap
➢ 371 - 372 mAh/g
+ Irrev. Cap.➢ 49.9 - 51.4 mAh/g
+ First cycle efficiency➢ 87.8 - 88.1%
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G16-0114: -635 Mesh1M LiPF6 in EC/DEC (1:1) Additives: NoneElectrochemical Data
• C/20 cycling+ Rev. Cap
➢ 351 mAh/g
+ Irrev. Cap.➢ 59.6 mAh/g
+ First cycle efficiency➢ 84.2 - 85.4%
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G16-0114GSP Ore, Graphite ConcentrateElectrochemical Data Summary
ID#
Flake Size
Ground to -635 mesh
eChem Results
Rev. Capacity(mAh/g)
Irrev. Capacity(mAh/g)
First Cycle Efficiency(%)
G16-0114
As Received 367 47.9 88.1
+50 Not enough material after sieving
50x100 Not enough material after sieving
100x200 366 42.4 88.6
200x400 375 48.3 88.0
400x635 371 49.9 88.1
-635 351 58.6 85.4
Lower Rev.Cap. due to impurities
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Natural Graphite Resources
• Samples from all over the world show the same capacity and similar process ability
• Samples are largely interchangeable if fines (-635 mesh) is removed
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LIB Lifetime
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Standard Cell Cycling at 21°C
• Cells cycle with limited capacity loss
• Variation in cell capacity are more a reflection of temperature stabilitythan cell capacity loss
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Cell Cycling
• Why do cells fail this way?+ See Jeff Dahn Win Talk and
explanation above
• What can you do?+ High Precision Coulometry
➢ Measure loss of electrons per cycle due to oxidation/reduction of the electrolyte
Cap
acit
y
Cycle Number
Cycles flat
Dies Quickly
Use HPC (High Precision
Coulometry) to determine
this point.
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HPC? Google Jeff Dahn Win Talk
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All rights reserved.34
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Prof. Jeff Dahn – WIN Talk
• Fresh cell
• Battery is charged and electrolyte starts to become oxidized on the positive electrode
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Prof. Jeff Dahn – WIN Talk
• Newish cell
• Reduction products start continue SEI layer growth on anode
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Prof. Jeff Dahn – WIN Talk
• Half way through life
• SEI layer thickening
• Pores start to close
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Prof. Jeff Dahn – WIN Talk
• Near end of life
• SEI has grown to the point where pores are beginning to clog and it is difficult for lithium to penetrate into the graphite anode material
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Prof. Jeff Dahn – WIN Talk
• End of life
• SEI has blocked access of lithium into the pores
• Lithium plating occurring on surface of the anode
• Lithium inventory is reduced each cycle and cell fails quickly
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Cell Cycling
• Why do cells fail this way?+ See Jeff Dahn Win Talk and
explanation above
• What can you do?+ High Precision Coulometry
➢ Measure loss of electrons per cycle due to oxidation/reduction of the electrolyte
Cap
acit
y
Cycle Number
Cycles flat
Dies Quickly
Use HPC (High Precision
Coulometry) to determine
this point.
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Coulombic Efficiency & Cell Life:Rapid Capacity Loss Cells
0 100 200 300 400
Moli Cycles
1.6
1.8
2
2.2
Ca
pa
cit
y (
Ah
)
0.992
0.996
1
CE
2100
2200
2300
2400
Ch
. E
nd
.C
ap
. (m
Ah
)
0 4 8 12 16 20
HPC Cycles
Control
VC
FEC
VC + FEC
11.91 mAh/cycle3.956 mAh/cycle5.333 mAh/cycle2.754 mAh/cycle
J. Electrochem. Soc., 160, A1451-A1456 (2013).
• Highest CE = longest life until rapid capacity loss
• Lowest CE = shorted life until rapid capacity loss
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HPC Testing
• HPC Testing results
• Tesla Cells+ 2013 Model S
+ Removed from damaged vehicle
+ 2.5-3.0 CIE/h
• STD Natural Graphite+ 5.0-6.0 CIE/h
C/20 to C/30 Cycling at 40°C
PUREGraphite
Gen2 – Graphite
Graphite is really important for
life!
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This work was supported by:National Science Foundation under Grant No. 1315040 (CVD
Process for Coating Graphite)
and by:Department of Energy under Grant No. DE-SC0015953 (High yield
spheronization).
Contact information:
Dr. Edward R. Buiel
Coulometrics, LLC
423-954-7766
Thank You!