Milena Stanga Technical Marketing Engineer SOLVAY GREEN PVDF FOR GREEN BATTERIES

Transcription

1 Milena Stanga Technical Marketing Engineer SOLVAY GREEN PVDF FOR GREEN BATTERIES

2 STATE OF THE ART

3 PVDF powder in NMP solvent PVDF is a partially fluorinated semi-crystalline polymer with excellent thermo-mechanical and chemical properties. Advantages of PVDF Stable adhesion during time High cohesion Long cycle life Good chemical affinity with commercial separator Better lamination process Good compatibility with artificial graphite Low resistivity for power application Disadvantages of PVDF Use of NMP (Toxic & costly)

4 A NEW WATER BASED BINDER COMBINING ADVANTAGES OF PVDF AND WATER

5 Solvay Specialty Polymers has taken advantages of its expertise in fluorine chemistry and polymerization technologies for design a new generation of fluoro-polymers for LIB Application Solvay introduces a novel fluorinated binder in aqueous dispersion with proprietary chemical modification (not blending materials) for improved adhesion and flexibility.

6 Solef PVDF water-based dispersions are stable and have the special feature of nano-sized primary particles of PVDF in the shape of spheres Latex viscosity: <5 cps [Brookfield, spindle#1, 60 rpm] Solid content of latex: 25-35% w ph: 3-5 (stable to ph adjustment up to 13) Stable to shear stress

7 Solef PVDF water-based ensures continuous film of binder between active material particles, through Thermal Process of Film Formation 1.Aqueous slurry Dispersion of AM/binder 2. Particles packing &deformation aggregation of PVDF primary particles & water evaporation 3.Coalescence Melting into Mechanically coherent dry film

8 Solef PVDF water-based ensures continuous film of binder between active material particles, through Thermal Process of Film Formation Graphite PVDF particles PVDF film after film formation

9 The chemical modification in Solef PVDF Latex ensures higher and more stable adhesion in combination with flexibility of the final electrode Solef PVDF Water Based Binder SBR Water Based Binder

10 Peeling strenght (N/cm) Applying the proper processing conditions, electrodes made with Solef PVDF Latex show same adhesion level as standard PVDF polymer processed in NMP 0,1 0,09 0,08 0,07 0,06 0,05 0,04 0,03 0,02 0,01 0 Solef PVDF Latex PVDF in NMP

11 Taking advantage of Solef PVDF Latex high adhesion and lower volume at equal weight compared to SBR, reduced amount of binder can be used increasing the amount of active material (to exploit the theoretical capacity and energy density of the battery).

12 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

13 Good interphase between electrodes and separator is a key factor to reduce internal resistance. Chemical affinity of PVDF with commercial polyolefin separators allows to laminate (ensuring better interface) them together. Lamination Polyolefin Separator with Electrode PVDF latex SBR latex Lamination NO Lamination

14 % Uptake % Uptake Swelling behavior of the electrode is a key parameter The electrode from PVDF latex is perfectly stable to both stressful treatments, showing very similar performance to SBR electrode, although pure PVDF polymer film is gellified at RT and is dissolved at 90 C Room Temperature <1h> <2h> <24h> < % uptake su materiale rimasto > 90 C PVDF XPH859 (Binder 3% v/v) SBR std (Binder 3% v/v) 0 PVDF XPH859 (Binder 3% v/v) SBR std (Binder 3% v/v)

15 Test: Cycling at 1C at RT Testing system: Full cell (pouch cell ) Anode formulation: 94 % SCMG, 3 % Super P, 1.2 % Solef Latex, 1.8 % CMC

16 Test: Cycling at 1C Testing system: Full cell (pouch cell 53437) Anode formulation: 89 % LTO, 5 % Super P, 5 % Solef Latex, 1 % CMC Aqueous based NMP based 1C CCCV 1D Voltage cut-offs : [1.5V 2.8V] RT Aqueous based NMP based 1C CCCV 1D Voltage cut-offs : [1.5V 2.8V] 55 C

17 GREEN PVDF FOR GREEN BATTERIES

18 Towards a fully water-based production process for all components of the battery: Preliminary validation of Solef PVDF Latex as binder at high voltage cathode NMC 532/carbon black/solef XPH 859=90/5/5 wt% Confirms residual water from all-aqueous processing is not a concern if routine secondary drying conditions are used. More effective and energy efficient to use dry-room air to remove trace adsorbed water than vacuum pumping for long time periods.

19 NMC 532/carbon black/solef XPH 859=90/5/5 wt%

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21 The ELIBAMA project is granted by the European Commission under the Nanosciences, nanotechnologies, materials & new production technologies (NMP) Theme of the 7th Framework Programme for Research and Technological Development.