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Lithium Ion Battery

Kynar® PVDF solutions have been used in lithium ion battery technology for many years as electrode binders for active materials. Arkema's continued innovation has led to solutions that are now being used for both anode & cathode binders and separator coatings. Experimental solutions are under development based upon low VOC waterborne latex technology.

Cathode Binders

Kynar® PVDF has been used in lithium ion batteries since the 1990's for its exceptional properties. Continued innovation led to the development of Kynar® HSV 900 and now Kynar® HSV 1800, which provide very strong adhesion for many active materials. High adhesion enables lower loading, which produces higher capacity batteries. Kynar® PVDF binders also demonstrate low solvent swelling even at high temperatures compared to alternative binder solutions, creating longer lasting batteries. Additionally, its electrochemical stability at these high temperatures is a key property for producing safer batteries.

 

Adhesion with Active Materials

  • LCO
  • LFP
  • LMO
  • NMC
  • NCA

Anode Binders

Similar to cathode solutions, Kynar® HSV 900 and Kynar® HSV 1800 provide high adhesion properties that enable lower loading. This yields a higher carbon content and thus a higher capacity battery.

 

Key Benefits

  • High adhesion (graphite, LTO)
  • High energy density
  • Increased carbon content
  • Lower internal resistance
  • Higher output (power)

Properties of Kynar® PVDF Binder Grades

 ThermalTGAFlexibilitySwellingSolution Viscosity
  Tg (ºC) Tm (ºC) △H (ºC) 5% weight loss,
in air (ºC)
10% weight loss,
in air (ºC)
(3mm mandrel) (in electrolyte @80ºC) @8%, 10s-1, RT (cp)

HSV 900

(Datasheet US/SI)

-40.8 163 50 448 456 Pass 37% 3350

HSV 1800

(Datasheet US/SI)

-40.9 162 51 450 460 Pass 37% 1750

*Tg = glass transition temperature; Tm = melt temperature; △H = heat of fusion

Adhesion Data

     

LCO / Carbon / Binder

97 / 1.5 / 1.5

HSV 900 1.0
HSV 1800 1.98
     

LFP / Carbon / Binder

93 / 4 / 3

HSV 900 1.0
HSV 1800 3.19

 

     

Graphite / Carbon / Binder

94 / 2 / 4

HSV 900 1
HSV 1800 5.76

High Temperature Performance

At high temperatures swelling can become an issue for many binder solutions, but comparatively, Kynar® HSV 900 and Kynar® HSV 1800 have low swelling even at 80ºC.

                 

Swelling (increase in weight %) in 1:1:1 DEM, DEC, EC for 24hrs

40ºC60ºC80ºC
HSV 900 18 23 37.9
HSV 1800 18 22 37.9

Boiling and Flash Points of Common Solvents for Kynar® PVDF

 Boiling Point (ºC)Flash Point (ºC)
Dimethyl Formamide (DMF) 153 67
Dimethyl Acetamide (DMAc) 166 70
Tetramethyl Urea 177 65
Dimethyl Sulfoxide (DMSO) 189 35
Triethyl Phosphate 215 116
N-Methyl-2-Pyrrolidone (NMP) 202 95
Acetone (for Kynar® Flex) 56 -18

Active Binder Developments

  • Flexible binders for fabrication of thick electrodes
  • High capacity anode systems for silicone active materials
  • High nickel content cathode

Separator Coatings

High voltage lithium ion batteries can become a safety hazard if the proper materials are not chosen. Typical polyolefin separator coatings require an added layer of protection that maintains mechanical properties as it swells, which enables higher voltages and temperatures to be safely reached. Kynar Flex® LBG (Datasheet US/SI) can be used to coat polyolefin separators, thereby enabling greater assurance against short circuiting. Solutions with up to 5V performance are available today. Kynar® PVDF can also be combined with ceramic fillers for improved mechanical properties.

  % Swelling in
 Kynar® gradeDMCDEC1:1:2 DMC/DEC/EC
30ºC Homopolymers 12 6 10
Kynar Flex® LBG 19 5 14
60ºC Homopolymers 27 12 30
Kynar Flex® LBG 50 15 58
75ºC Homopolymers 38 15 45
Kynar Flex® LBG Dissolved 31 Dissolved

Use for Extreme Battery Applications

xEV batteries are extremely demanding in terms of durability, longevity, and safety requirements. Kynar Flex® PVDF solutions enable this through exceptional dimensional stability, even at temperatures above 70ºC, which helps mitigate lithium dendrite growth across the polyolefin separator due to an increase in ionic transportation. This ultimately enables higher power and lower risk of short circuiting.

 

*FOR EXTREME DEMAND — Kynar® PVDF can be combined with nano-ceramics for improved properties*

Water-Based Binders

Kynar® water-based binders have the potential to eliminate volatile organic processing solvents (e.g. NMP, Acetone) and present advantages in cost, safety, and overall performance.

 

Water-based latexes are polymerized using the emulsion process. This enables the creation of nano-scale particles, with increased surface area and improved film formation during the coating process. Kynar® PVDF is made through emulsion polymerization.

 

Formulation of fluoropolymer latexes requires a different set of tools and processes for optimization vs. solvent-borne. Arkema is a world leader with an extensive patent portfolio in water-borne technology, especially aqueous fluoropolymer coatings and formulations.

 

 

Experimental Kynar® PVDF latex grades for separator coating are available upon request. Contact our team below for more information.

View and Download Our Lithium Ion Battery Brochures

Let's Run Together

Our range of materials is constantly growing.  As the market demands higher performance materials we will continue to develop innovative solutions.  Our global team of engineers is eager to work on new developments and design creative solutions for your material needs.  Contact our team today to start your development.

 

Contact Our Battery Team

 
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