New PVDF Developments for High Performance Li-Ion Batteries and Sustainable Battery Processing

Transcription

1 New PVDF Developments for High Performance Li-Ion Batteries and Sustainable Battery Processing V. Arcella, R.Pieri and F.Triulzi FLUOROPOLYMER 2014 San Diego, CA October

2 Solvay History Solvay was Founded in 1863 by Ernest Solvay Solvay The first Solvay Physics Conference in 1911, included 8 Nobel prize winning chemists and physicists: Marie Curie, Albert Einstein, Onnes Kamerlingh, Hendrik Lorentz, Walther Nernst, Max Planck, Ernest Rutherford, Jean Perrin 2

3 Solvay Group A major global player in Chemistry Our strengths 90% of sales in businesses among the top 3 global leaders 38% of sales in fast growing markets Balanced portfolio of activities A culture of sustainability, innovation and operational excellence 12.4bn NET SALES 2.1bn Adjusted REBITDA 111 MAJOR INDUSTRIAL SITES 12 MAJOR R&D CENTERS 29,100 EMPLOYEES 55 COUNTRIES 3

4 Pillars of Sustainability We commit to take into account, in a way that is comprehensive and integrated in all our activities, the triple demand of economic, societal & environmental sustainability 4

5 Solvay Specialty Polymers - Leading at the top of the pyramid with the widest product portfolio High-Performance Polymers Industry Characteristics Top part of plastics pyramid High-tech products High barriers to entry Driving and driven by innovation Market and application development Large variety of markets Performance Attributes Temperature Resistance Chemical Inertness Weathering Resistance Corrosion Protection Water Repellency Stain Repellency Electrical Inertness Non-Flammability Fatigue Resistance Biocompatibility Extractables Self-Cleaning Transparency Heat Transfer Processability Toughness Elasticity Barrier Tribology Release Color 5

6 Solvay Specialty Polymers - Serving well-diversified and highly dynamic markets Emerging Markets Net Sales % in % Healthcare 8% Smart Devices 3% Water 8% Energy 16% Industrial 2% Advanced Transportation 10% Electrical/Electronics 22% Automotive 11% Consumer 10% Construction Traditional Markets 6

7 Solvay Specialty Polymers - International Presence Newark Marshallton West Deptford Greenville Tavaux São Paulo NOH Oudenaarde Rheinberg Düsseldorf Roccabianca Spinetta Ulsan Seoul Tokyo Fuji City Shanghai Changshu Augusta Marietta Bollate Taiwan Panoli Vadodara Mumbai Alpharetta Singapore Orange Pretoria Bay St. Louis = Headquarters = Plant = Sales & Administration = Research, Development & Technology 7

8 Agenda PVDF General Overview New PVDF developments in Li-Ion Batteries o Anode o Cathode 8

9 Agenda PVDF General Overview New PVDF developments in Li-Ion Batteries o Anode o Cathode 9

10 PVDF General Overview PVDF (Solef & Hylar ) F F F F F F PVDF is a partially fluorinated semi-crystalline polymer with excellent thermo-mechanical and chemical properties The best mechanical properties of all fluoropolymers Good chemical resistance up to 150 C Outstanding weathering resistance PVDF has typical two-phase morphology: crystalline + amorphous Crystalline phase: crystalline lamellae organized in spherulites Amorphous phase: glass transition at -45 C 10

11 PVDF General Overview PVDF: two different polymerization processes PVDF FROM SUSPENSION Bulk density~ g/cm 3 Spheroidal particles μm Free flowing powders 11

12 PVDF General Overview PVDF: two different polymerization processes PVDF FROM EMULSION Bulk density~0.2 g/cm 3 Ø Primary particles~ nm Irregular shape of secondary particles 2-20 μm 12

13 PVDF General Overview PVDF : Polymerization & Molecular Structure The ideal PVDF chain is regular alternation of CH 2 and CF 2 groups -CH 2 -CF 2 -CH 2 -CF 2 -CH 2 -CF 2 -CH 2 -CF 2 A real PVDF chain contains structural defects monomer inversions short branches long branches CH 2 CF 2 -CH 2 -CF 2 -CH 2 -CH 2 -CF 2 -CH -CF 2 -CH 2 13

14 PVDF General Overview PVDF : Polymerization & Molecular Structure Monomer Inversions -CH -CH 2 -CF 2 -CF 2-2 T H CH 2 =CF 2 1. regular addition : Head- to-tail -CH 2 -CF 2 -CH 2 -CF 2 -CH 2 -CF Most probable 2 T H T H 2. inverted addition : Head- to-head P(HT) 1 -CH -CH -CF 2 -CH 2 -CF 2-2 -CF 2 2 T H H T Less probable P(HH)

15 PVDF General Overview PVDF : Polymerization & Molecular Structure Monomer Inversions -CH -CH 2 -CF 2 -CF 2-2 T H CH 2 =CF 2 3. repairing addition on H-H inversion -CF -CH -CF 2 -CF 2 -CH 2 -CH 2 -CF Highly probable T H H T T H P(TT) 1 4. non repairing addition on H-H inversion -CF -CH -CF 2 -CF 2 -CH 2 -CF 2 -CH Much Less probable P(TH) << 0.01 T H H T H T 15

16 PVDF General Overview Monomer inversions in PVDF Polymerisation Temperature ( C) H-H (%) R. E. Cais, J. M. Kometani, Macromolecules,1984, 17, M. Görlitz et al., Angew. Makromol. Chemie, 1973, 29/30, 137. R. Liepins et al., J. Polym. Sci., Polym. Chem. Ed., 1978, 16,

17 PVDF General Overview Branching in PVDF The amount of chain ends measured by 19 F NMR is not compatible with the polymer number-average MW large amount of chain ends - CF 2 H and CH 3 EW about few thousands M N > g/mol 17

18 PVDF General Overview PVDF : Polymerization & Molecular Structure Branching Long debate about nature of branching: fundamental contributions came from Industry M. Pianca, E. Barchiesi, G. Esposto, S. Radice, J. Fluorine Chem., 95, 71 (1999). Hedhli, L., Mekhilef, N., Moyses, S., Lewis, R.H., Macromolecules, 41, 2011, (2007) Shared vision Two possible types of side chains, both covalently bond to the backbone short chains long chains 18

19 PVDF General Overview Short Chain Branching (SCB) in PVDF CF 2 CH 2 -CF 2 -CH H. CH 2 CF 2 CF 2 -CF 2 -CH-CH 2 -CF 2 -CH 2 -CF 2 H. VF 2 CF 2 -CF 2 -CH-CH 2 -CF 2 -CH 2 -CF 2 CH 2 SCB occurs with H abstraction on a HH inversion CF 2 CH 2 CF 2 H M. Pianca, E. Barchiesi, G. Esposto, S. Radice, J. Fluorine Chem., 95, 71 (1999). 19

20 PVDF General Overview Short Chain Branching (SCB) in PVDF T m ( C) (T m ) H-H = 0 = 200 C Tm reduces with monomer inversions, most probably through SCB formatioin H-H (% mole) T m ( C) A. K. Nandi, L. Mandelkern, J. Polym. Sci.; Part B, Polym. Phys., 1991, 29,

21 PVDF General Overview Long Chain Branching (LCB) in PVDF only in Emulsion PVDFs at relatively high T different cause from SCB branch points occur on a methyne between two CF 2 groups H abstraction from radicals (initiator or chain) Hedhli, L., Mekhilef, N., Moyses, S., Lewis, R.H., Macromolecules, 41, 2011, (2007) 21

22 PVDF General Overview Long Chain Branching (LCB) in PVDF Chain branching effect on solution rheology 22

23 PVDF General Overview PVDF : Polymerization & Molecular Structure PVDF microstructure Engineering model 1) R 1 O-O R 2 2RO 1 2RO 1 Pn INITIATION AND PROPAGATION 2) P n -CH 2 CF 2 + CH 2 =CF 2 P n+1 -CH 2 CF 2 PROPAGATION nm 4) P n -CH 2 CF 2 + CF 2 =CH 2 P n+1 -CF 2 CH 2 PROPAGATION TO HHTT DEFECTS 5) P n -CH 2 CF 2 + P n+1 -CH 2 CF 2 -Pm P n+1 -CHCF 2 -Pm + P n+1 LONG CHAIN BRANCHING (LCB) 6) P n -CH 2 CF 2 P n+1 -CF 2 CHCH 2 CF 2 CH 2 CF 3 SHORT CHAIN BRANCHING (SCB) 7) P n + T P n + T TERMINATION TO CHAIN TRANSFER 8) P n + P m P n+m BIMOLECULAR TERMINATION 23

24 PVDF General Overview PVDF : Polymerization & Molecular Structure Suspension polymerization low T & high P More ordered microstructure low T High P Emulsion polymerization High T & moderate P More Irregular microstructure low P high T Only Solvay has both technologies and there are benefits to both 24

25 PVDF General Overview Polyvinylidene Fluoride (PVDF) Solef applications in actual market Oil and Gas industry: Off-shore Plumbing, Membranes and Water treatment Membranes for water treatment PVDF Hot water transportation 25

26 PVDF General Overview Polyvinylidene Fluoride (PVDF) Solef applications in actual market Chemical Processing industry: Heat Exchanger in strong acidic and hot temperature environment Wire and Cable: Fire resistance Chemical resistance Dielectric properties Mechanical flexibility 26

27 Agenda PVDF General Overview New PVDF developments in Li-Ion Batteries o Anode o Cathode 27

28 New PVDF developments in Li-Ion Batteries PVDF is well established as cathode binder PVDF (Solef & Hylar ) PVDF is well known in the lithium battery industry, bringing many advantages when used in formulation as cathode binder Advantages Superior ageing resistance High thermal and chemical resistance High electrochemical stability up to 5V Low swelling levels in electrolytes (PVDF homopolymers) High flexibility (PVDF copolymers) 28

29 New PVDF developments in Li-Ion Batteries PVDF is well established as cathode binder PVDF (Solef & Hylar ) PVDF is well known in the lithium battery industry, bringing many advantages when used in formulation as cathode binder ANODE Market Trend At the anode the current trend is SBR used as water based LATEX dispersion CATHODE PVDF is the preferred choice for cathode, and usually requires the use of solvent-based processing 29

30 New PVDF developments in Li-Ion Batteries - ANODE New PVDF developments: Towards PVDF Water Based THE GOAL Develop new PVDF water dispersions for binders, to be used at both positive and negative electrodes, with high performances and durability in Li-Ion batteries TECHNICAL SOLUTION Apply the Solvay s functionalised PVDF technology, already used at cathode with many advantages. Expected same advantages also if used as anode binder 30

31 New PVDF developments in Li-Ion Batteries - ANODE Binder for the Anode SBR is the Benchmark SBR is an amorphous polymer with good thermo-mechanical and chemical properties Advantages of SBR Water based system Low cost Good mechanical performance Good compatibility with graphite (especially natural) Disadvantages of SBR High resistance (not good for power) Low chemical affinity with commercial separator 31

32 New PVDF developments in Li-Ion Batteries - ANODE Look beyond SBR latex PVDF New aqueous dispersion PVDF containing special functionalities PVDF particles A new f-pvdf Water Based - Solef EXP latex Stable water dispersion Surfactant free (Patented technology) 32

33 New PVDF developments in Li-Ion Batteries - ANODE Look beyond SBR latex PVDF Solef EXP latex : High MW functionalized PVDF Increased interactions among ingredients of the electrode system and the metal current collector Functionalized PVDF technology High MW Improves cohesion of active materials and adhesion to metal collector Polar functional groups promote and enhance better adhesion among all surfaces of the electrode system 33

34 New PVDF developments in Li-Ion Batteries - ANODE Water Based Processing Raw materials Graphite Deionized Water Additives PVDF latex (Binder) Slurry Electrode Coating Drying Pressing 34

35 New PVDF developments in Li-Ion Batteries - ANODE Water Based Processing It is necessary to ensure continuous film of binder among active material particles 1. Aqueous slurry dispersion of active materials in PVDF latex 2. Casting & Water evaporation aggregates of PVDF primary particles 35

36 New PVDF developments in Li-Ion Batteries - ANODE Water Based Processing Film formation Coalescence of particles and formation of a continuous film The functionalization in PVDF ensures improved higher and more stable adhesion in the final electrode Peeling strength [N/cm] 0,3 0,2 0,1 binder 3% w/w binder 3% w/w binder 2% w/w Solef f-pvdf Latex SBR Latex PVDF Latex f-pvdf better than SBR 0,0 binder 3% v/v binder 3% v/v binder 3% v/v 36

37 New PVDF developments in Li-Ion Batteries - ANODE Water Based Processing Mechanical Performance Flexibility is a key property which determines final performance of batteries. A good binder guarantees the electrode to be bent in winding or z-fold configuration with no cracks formation Bending test Electrode (binder: 3%) Φ : 4 mm Φ : 2 mm SBR O O* Solef EXP Latex O O* X: Cracks, O: No cracks, O*: Small cracks f-pvdf Equivalent to SBR 37

38 New PVDF developments in Li-Ion Batteries - ANODE Water Based Processing Electrode/Separator affinity f-pvdf laminates well with Polyolefine seaparators: Good interphase between electrodes and separator is a key factor to reduce internal resistance Lamination Polyolefin Separator with Electrode f-pvdf latex CAN be Laminated SBR latex CANNOT be Laminated f-pvdf better than SBR 38

39 New PVDF developments in Li-Ion Batteries - ANODE Water Based Processing Swelling Swelling at different temperatures (24h at RT and 8h at 90 C) in EC/DMC 1/1 was measured on polymer film (obtained from latex by drying and pressing) as well as on electrodes. Room Temperature <1h> <2h> <24h> < % uptake su materiale rimasto > 30 % Uptake PVDF XPH859 (Binder 3% v/v) SBR std (Binder 3% v/v) f-pvdf Equivalent to SBR 39

40 New PVDF developments in Li-Ion Batteries - ANODE Water Based Processing Swelling Swelling at different temperatures (24h at RT and 8h at 90 C) in EC/DMC 1/1 was measured on polymer film (obtained from latex by drying and pressing) as well as on electrodes. 90 C 30 % Uptake PVDF XPH859 (Binder 3% v/v) SBR std (Binder 3% v/v) f-pvdf Equivalent to SBR 40

41 New PVDF developments in Li-Ion Batteries - ANODE Water Based Processing Solef f-pvdf aqueous dispersion is electrochemical stable at low voltage, necessary condition for binder at anode. Electrochemical Stability at Anode Current [ma] Solef PVDF Latex SRB/CMC Standard PVDF/NMP Voltage vs. Li + /Li [V] f-pvdf Equivalent to SBR

42 New PVDF developments in Li-Ion Batteries - ANODE Water Based Processing Electrochemical behavior is better than SBR at high C-rate (power density) due to lower internal resistance. Rate capability Specific capacity [mah/g] Solef PVDF WB 1%wt Solef PVDF WB 10 %wt SBR 1% SBR 10 % C-rate Formulations: 89/1/10 AM/CMC/Binder, 98/1/1 AM/CMC/Binder Electrode thickness: µm, Loading: 1.8 mah/cm, Porosity: about 50 %, not calendered f-pvdf much better than SBR 42

43 Agenda PVDF General Overview New PVDF developments in Li-Ion Batteries o Anode o Cathode 43

44 New PVDF developments in Li-Ion Batteries - CATHODE PVDF is well established as cathode binder PVDF (Solef & Hylar ) The current situation Li-Ion Battery process for cathode binder Organic uses Solvents Organic Solvents (NMP) Develop a Water based Solution LIFE+GLEE Technology 44

45 New PVDF developments in Li-Ion Batteries - CATHODE The Problem: Cathode active materials (CAM) are not stable in water s The challenge: Maintain the high performance of PVDF by the solvent process, even using a water based PVDF NO toxic risks associated with the use of organic solvents Lower manufacturing costs for solvent recovery and re-purification 45

46 New PVDF developments in Li-Ion Batteries - CATHODE The Alternative: Develop a Water based Solution Enabling Water-based PVDF solution for Cathode Active Materials LIFE+GLEE technology: coated LCO Discharge Capacity (mah/g) C/10 C 2C NMP + LCO std Latex + plco (GLEE) Latex + LCO std cycle n 46

47 New PVDF developments in Li-Ion Batteries - CATHODE The Alternative: Develop a Water based Solution The LIFE+GLEE pilot plant A demonstration pilot plant is under construction at Solvay Specialty Polymers RD&T Center in Bollate (Milan), Italy, funded by the EU, within the frame of the LIFE program. The pilot will use a fully automated apparatus to produce ca. 1kg of Coated Active Material (CAM) per day. 47

48 Conclusions Solef PVDF latexes can be used in water based formulations at both cathode and anode At the Anode we obtained equivalent flexibility, swelling and electrochemical stability of SBR, while better adhesion and lamination behavior, and much better ionic flow resistance, crucial for Power batteries The protecting metallic layer on Cathode Active Material (GLEE technology), allows to use PVDF latex also at the Cathode, eliminating toxic solvents historically used in the rechargeable Li-Ion battery manufacturing processing The coating protecting layer for the Cathode Active Material (LIFE-GLEE technology) allows to reduces manufacturing costs for solvent recovery and purification, and improves performance of the batteries. 48

49 Thank you 49