Artificial Graphite for Lithium Ion Batteries

Transcription

1 Artificial Graphite for Lithium Ion Batteries Dr. Roland Müller London, 6. Dec 2011

2 Agenda Group at a Glance Graphite Properties Production of Artificial Graphite Anode Materials in Lithium Ion Batteries Natural Graphite in Battery Application & Outlook Page 2

3 Company profile Group is one of the world s largest manufacturers of carbon-based products Comprehensive portfolio ranging from carbon and graphite products to carbon fibers and composites 45 production sites worldwide Sales of ~ 1,4 bn in 2010 Head office in Wiesbaden/Germany Approx. 6,300 employees worldwide Listed on MDAX Service network covering more than 100 countries Page 3

4 Best Solutions: Best in class products, services and ideas to satisfy current and future needs of our customers Our markets Iron and steel Aluminium Semiconductor High temperature technology Mechanical engineering Automotive Chemicals Energy and environmental technology LIB Anode materials Aerospace High performance sports Page 4

5 Our carbon based products offer sustainable solutions towards less CO Sales (in m) Aerospace Automotive approx. 65% of Group Sales Wind ~ % 10% Light weight Alternative energies Solar Scrap recycling 80% Energy efficiency Batteries Automotive Cooling systems Page 5

6 Agenda Group at a Glance Graphite Properties Production of Artificial Graphite Anode Materials in Lithium Ion Batteries Natural Graphite in Battery Application & Outlook Page 6

7 Greek: Graphein = to write Lattice of graphite Pencils Diamonds Page 7

8 Graphite Monocrystal properties parallel perpenticular to atomic layer density 2,27 2,27 [g/cm³] E Modulus 10 0,35 [GPa] spec. electr. 0,5 10,000 resistance [µ Ω m] therm. expansion -1,5 28,6 [10E-6/K] therm. conductivity > 400 < 8 [W/mK] layer line distance 0,142 0,335 [nm] Page 8

9 Agenda Group at a Glance Graphite Properties Production of Artificial Graphite Anode Materials in Lithium Ion Batteries Natural Graphite in Battery Application & Outlook Page 9

10 Artificial Graphite: Manufacturing Process Raw material storage Coke, graphite, anthracite Pitch Weighting Mixing Crushing Grinding Extrusion Vibro-moulding Isostatic pressing Screening, Sieving Baking ( ~ 1000 C ) Impregnation Rebaking Storages for classified fractions + - Graphitization (3000 C) Page 10

11 Production of Artificial Graphite Raw materials coke, pitch Coal tar pitch coke, isotropic Petrol coke, regular Milling Mixing Molding Coal tar pitch coke, needle Natural graphite Baking Graphitizing Milling Page 11

12 Production of Artificial Graphite Raw materials coke, pitch Mill Milling Mixing Molding Mixer Baking Graphitizing Milling Page 12

13 Production of Artificial Graphite Raw materials coke, pitch Extrusion Die-molding Milling Mixing Molding Baking Vibrating Isostatic pressing Graphitizing Milling Page 13

14 Production of Artificial Graphite Raw materials coke, pitch Ringfurnace Milling Mixing Molding Baking or alternatives: Tunnel Furnace Belt Furnace Car Bottom Kiln Cover Furnace Graphitizing Milling Page 14

15 Production of Artificial Graphite Raw materials coke, pitch Milling Mixing Molding Baking Graphitizing Milling Acheson Graphitisation Long Process Times Various Formats Castner Lengthwise Graphitisation Shorter Process Times Same cross section Page 15

16 Graphitization Development of Crystallite Alignment Graphite lattice formation 800 C Calcination Puffing Graphitization S&N Hexagonal Graphite 1200 C release (abab) 1400 C c/2 3,44-3,354 Å Lc Å 2200 C La Å >2400 C Carbon Source: Marsh, 1991 Graphite Page 16

17 Agenda Group at a Glance Graphite Properties Production of Artificial Graphite Anode Materials in Lithium Ion Batteries Natural Graphite in Battery Application & Outlook Page 17

18 Li-Ion Batteries Operation Principle negative electrode electrolyte positive electrode Negative electrode / Anode: Graphite charge discharge Positive electrode / Cathode: LiCoO 2 LiC 6 C 6 + Li + + e - 2 Li 0.5 CoO 2 + Li + + e - 2 LiCoO 2 Cell reaction: LiC Li 0.5 CoO 2 C LiCoO 2 Page 18

19 Carbon & Graphite in LIB + C /G conductive additives Carbon / Graphite + C /G conductive additives Carbon / Graphite Carbon / Graphite Carbon / Graphite Source: J.-M. Tarascon, M. Armand; Nature 414 (2001), 359. Page 19

20 Characterisation of Graphites for Li-Ion Batteries Crystallite Size Determination by X-ray diffraction (XRD) and Raman spectroscopy L c > ca. 50 nm L a < ca. 100 nm d (002) <= ca. 3,38 Å Rapid charge / discharge Good cycling stability Smaller L c Larger L a Larger d (002) Capacity tends to decrease d (002) L c L a Page 20

21 Synthetic Graphite for Li-Ion Batteries First Cycle Irreversible capacity (= charge capacity - discharge capacity) = Coulomb Efficiency Staging compounds: Potential (V) IV LiC III LiC II L LiC 18 II LiC 12 I LiC 6 Intercalation 0.25 Charge Discharge Capacity (mah/g) Page 21

22 Comparison Hard Carbon, Soft Carbon & Synthetic Graphite Rate Capability Hard Carbon Li Soft Carbon Li Graphite Li X Synthesis Temperature: C Significant properties changes with temperature Synthesis Temperature: C Page 22

23 Rate Capability of Different Carbon Types for LIB & Their Raw Materials Capacity (mah/g) Natural Graphite Soft Carbon Hard Carbon Synthetic Graphite Artificial Graphite Soft Carbon Hard Carbon Natural Graphite Measurement: CC; potential window: V vs. Li metal C-rate Consumer EV HEV Page 23

24 Comparison of Carbon / Graphite Item Source: Hard Carbon Soft Carbon Graphite Low Crystallinity High Model Strength High Stability versus electrolyte = Long Life High power density Coexistence High Coulomb Efficiency > 90-95% High electrode density Weakness Low Coulomb Efficiency % Low electrode density CE 80 85% Improvement Low Stability versus electrolyte = Short Life Poor power density Page 24

25 Characterisation of Graphite for Li-Ion Batteries Particle Shape and Orientation in the Composite Electrode Li + Li + x Particle shape and its orientation and particle size distribution determine the - electrode density ( packing density ) - electrical resistivity ( contact points between particles ) (and thus energy density and power density) and electrode kinetics (rate capability and power) Example of composite electrode: Flake-type graphite: ~ g/cm 3 Spherical graphite: up to 1.7 g/cm 3 Page 25

26 Graphites for Li-Ion Batteries From Materials to Performance Materials and Tools Raw materials Coke base Pre-treatment Grinding and crushing Graphitisation process Procedure / Oven Temp. and duration Post-treatment Grinding and crushing Morphology tailoring Chemical modification Coating Materials Properties Structure 2H/3R ratio Turbostratic disorder Lattice defects Morphology Particle shape Particle size Particle size distribution BET surface area Porosity Chemistry Surface chemistry Lattice doping Electrochemical Performance Reversible capacity Irreversible capacity Cycling stability Rate capability PC tolerance Ageing behaviour Self-Discharge Electrode Processability Safety Page 26

27 Comparison of Anode Materials for Automotive Batteries Material Energy Life Power Safety Cost EV HEV Artificial Graphite ++ + o + o ++ o Natural Graphite * ++ o o o ++ + o Hard Carbon o o o ++ Soft Carbon o o ++ * with Coating Page 27

28 Agenda Group at a Glance Graphite Properties Production of Artificial Graphite Anode Materials in Lithium Ion Batteries Natural Graphite in Battery Application & Outlook Page 28

29 Substantial Growth for Automotive Applications from = C Stationary e-mobility Anode Materials for LIB Page 29

30 Spherical Natural Graphite Demand mt/a C Auto tot Source: /IIT Page 30

31 Production concentration of critical raw minerals materials 74% of world NG production out of China Source: Industrial Minerals Page 31

32 Flake Graphite has to be rounded for LIB applications Rounding is a difficult mechanical process carried out in an array of mills. Currently it has a low yield of 30-40% only Page 32

33 Outlook: Graphite for LIB Spherical Natural Graphite plays an important role due to good cost / performance ratio Volume scenarios for 2020 require a significant increase in Natural Graphite mining & processing Capacity ( yield for SNG ) Supply risk assessments will play a more important role in reliable supply chains with focus on local EV productions Artificial Graphite is the choice for high performance LIB Raw material availability for Artificial Graphite is NOT restricted or highly concentrated. Capacity can be ramped up according to demand Artificial Graphite has potential for further cost / performance improvements regarding EV / PHEV / HEV Page 33

34 Summary based on Group is the leading Artificial Graphite Anode Material Producer more than 100 years experience in Carbon / Graphite business more than 10 years in manufacturing anode material plus innovative materials for energy storage thermal management ( ECOPHIT ) conductive additive ( Conductograph ) EDLC supercaps Carbon felts for Redox Flow Batteries ( SIGRACELL ) Bipolar plates for Redox Flow Batteries ( SIGRACET ) Page 34

35 Thank You for Your kind Attention Page 35