Specialty Polymers for Li-Ion Battery Cells

Lithium-ion-battery-layers

Solvay offers a portfolio of specialty polymers formulated to provide Lithium-Ion (Li-Ion) batteries with long-term durability, chemical and electrochemical resistance and high-temperature performance to enhance sustainability, increase battery energy density, streamline manufacturing and reduce environmental footprint. Specifically, our cost-effective, high-performing plastics are manufactured with superior properties increase adhesion, cycle life and processability in cathode binders, and increase strength and chemical resistance in separators and cell gaskets.

Today’s Li-Ion batteries must deliver increased energy in more compact spaces. Accordingly, OEMs demand components with high voltage tolerance, high temperature compatibility, extended cycle life and simplified processing for outstanding performance, manufacturing and storage compatibility. Additionally, the rapid expansion of the Li-Ion battery industry, OEMs simultaneously require innovative solutions and materials with eco-friendly processing methods. Our polymerization technologies deliver a family of specialty polymers that meet and exceed these lithium battery performance and processing expectations. For example, Solvay continues to lead the battery market in environmentally friendly solutions with the development of the first commercialized water-based Polyvinylidene Fluoride (PVDF) for separator coatings. 

 

Binders and Separators

Improved Battery Energy Density

Modern batteries require higher energy densities to deliver optimum performance in downsized, more efficient systems and storage. Solvay’s polymerization technology facilitates chemical modification to improve the adhesiveness and flexibility of cathode binders used in high density electrodes. The unmatched cohesion and adhesion of our industry-leading PVDF binders allows manufacturers to utilize less binder content, which enables miniaturization and enhances performance and enhances performance. Specifically, Solef® PVDF is a partially fluorinated polymer with excellent chemical properties and tremendous temperature tolerance to provide unparalleled adhesion and anti-gelation and ensure maximum efficiency in the production and performance of an array of Li-Ion batteries. 

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Adhesion is a key property which determines final performance of batteries, especially in the long term. A good binder guarantees the homogeneous dispersion of active materials and conductive carbon together with stable bonding to the metallic collector.

Adhesion comparison

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Enhanced Durability and Stability

Reliable Li-Ion batteries require highly adhesive binders with significant flexibility and a dependable interface between the separator and the electrodes to ensure long-term performance. The excellent adhesion of Solvay’s high-quality polymers for battery binders offers continued stability over extended periods. Additionally, our engineers coat the separators with additional layers of PVDF which increases wettability and enables high lamination strength within the cell. Solef® PVDF is available in several modified grades used in both high-performance binders and adhesive separator coatings to increase cycle life by limiting the leakage of electrolytes in modern Li-Ion batteries.

 

Unmatched Versatility and Innovation

Solvay’s Solef® PVDF is manufactured with outstanding mechanical properties to offer extreme versatility in various designs for separators, as a main component or as additional adhesive separator coatings. In addition, this high-performance, flexible polymer can be modified to create dense gelled or porous separator membranes, as well as traditional solvent-based coatings or industry-first, water-based coatings. Solef® PVDF offers all the benefits of a high-purity resin with chemical and electrochemical stability, fast wettability, controlled leakage of electrolytes and outstanding adhesion even in the harsh environments found in a lithium battery.

 

Solvent-Based Versus Water-Based Separators

Traditional, solvent-based separator coatings in Li-Ion batteries improve the interface between the electrodes and separators to extend cycle life and improve wettability and assembly. Solvay’s unique solvent-based PVDF separator coating is manufactured with Solef® PVDF, a modified copolymer that offers good adhesion, excellent chemical resistance and high lamination strength.

With the introduction of the industry’s first commercialized water-based PVDF for separator coatings, Solvay’s Solef® PVDF Water Based Coatings avoid usage of irritant organic solvents and are available in various grades for formulation flexibility and ease of processing. Solef® XPH, our family of latex PVDF copolymers, utilizes a completely solvent-free coating process and provides OEMs with a high-performing, eco-friendly solution separator coatings.

 

Solef® PVDF for battery separators

Solef-pvdf-grades-for-battery-separators

 

Optimized Processing and Manufacturing

As lithium battery applications continue to evolve, OEMs require binders and separators with more advanced and flexible properties than ever before to facilitate streamlined formulation and manufacturing. Solvay’s specialty polymers for lithium battery binders are designed with medium-high molecular weight to provide excellent adhesion for simplified, easy and safe manufacturing processes and slurry preparation. Our versatile materials for Li-Ion separator membranes and coatings offer a variety of grades and flexibility to satisfy requirements in a range of applications.

 

Cell Gaskets

Advanced Fluoropolymers for Critical Seals

As Li-Ion battery technology evolves, Solvay provides OEMs with high-performance fluoropolymers for cell gaskets to extend battery life and improve battery processing safety. Specifically Hyflon® MFA® (perfluoropolymer) and Tecnoflon® FKM (fluoroelastomer) deliver critical sealing properties with superb chemical, flame and high voltage resistance for improved processability and exemplary sealing performance during operation. Hyflon® MFA® is equipped with exceptional chemical inertness and flame resistance to deliver longevity and durability in modern Li-Ion batteries. Tecnoflon® FKM exhibits excellent mold flow and release to ensure good processability of cell gaskets. These fluorinated materials provide Li-Ion battery manufacturers with cost-effective component design flexibility while meeting the industry’s advanced performance requirements. 
 

Specialty Polymers for Lithium Ion Batteries 

Solef® PVDF

Solef® PVDF (polyvinylidene fluoride) is a partially-fluorinated, semi-crystalline polymer with outstanding adhesion and high flexibility for optimal use in an array of Lithium-Ion (Li-Ion) battery applications. This high-quality thermoplastic offers excellent thermo-mechanical and chemical properties and is available in a variety of versatile grades for both binders and separator coatings. The homopolymer PVDF delivers high crystallinity levels which provide high resistance in typical electrolytes used in Li-Ion batteries, and the PVDF copolymers offer lower crystallinity and low swelling for a wide range of soluble separators in gel polymer type batteries. The superior lamination, chemical resistance and good slurry stability of Solef® PVDF enables reduced binder content, which facilitates higher battery energy density, improved power performance and a longer cycle life. 

Solef® PVDF is equipped with high purity to guarantee enhanced safety and extremely low levels of contamination. Due to its electrochemical stability, Solef® PVDF remains safe for use in the full range of voltage and high temperatures. Additionally, Solef® PVDF pipes remain stable for more than 50 years under 25 MPa at room temperature, in accordance with ISO 9080 extrapolation standards. 

The high adhesion and high flexibility of Solef® PVDF are ideal for cathode binders in high capacity Li-Ion batteries. Additionally, Solef® PVDF is available for either solvent-based or water-based separator coatings. 

 

Hyflon® PFA and MFA®

Hyflon® PFA and MFA® resins are thermo-processable perfluorinated polymers specifically designed for high temperatures and unparalleled chemical resistance to increase battery cycle life and improve processing safety. This family of rigid fluoropolymers combines exceptional value with excellent dielectric properties for modern Li-Ion batteries. Additionally, the high melt flow rate and inherent flame resistance of Hyflon® MFA® facilitate long-lasting, reliable seals. Different grades of Hyflon® are available to meet customized performance, efficiency and processing requirements.

 

Tecnoflon® FKM

Tecnoflon® FKM is a family of fluoroelastomers distinguished for its exceptional chemical resistance and operational temperature range in the most demanding environments. Fluoroelastomers surpass standard elastomers in purity and performance due to the strength of the Carbon-Fluorine bond. Additionally, Tecnoflon® FKM is formulated with low post cure and excellent mold flow to ensure superior processability and component design flexibility. These properties, combined with excellent mold release, make Tecnoflon® the material of choice for high demanding sealing applications that meet the stringent requirements of modern chemical processing. 

 

Hyflon® MFA® and Tecnoflon® FKM are ideal fluoropolymers and fluoroelastomers for cell gaskets in the most advanced Li-Ion batteries. The chemical and thermal insulating properties of Hyflon® help cell gaskets to achieve excellent sealing performance during operation, high CTI (comparative tracking index), electrochemical resistance and good processability. Tecnoflon® FKM provides a high-performance, flexible alternative for more demanding environments and sealing in cell gaskets to improve the electrolyte containment efficiency and safety of each cell.