Overview of PVDF Binder in Lithium Batteries
Polyvinylidene fluoride (PVDF) is a semi-crystalline fluorinated polymer that is soluble in polar organic solvents and possesses high viscosity and adhesive properties.
The electrode binder materials for lithium batteries prepared with PVDF exhibit excellent chemical stability, temperature stability, and a strong affinity for the electrolyte. Consequently, it has consistently garnered significant attention.
With the rapid advancement in lithium-ion battery technology and market growth, PVDF has witnessed a substantial upward trend in the lithium-ion battery industry, with an annual demand growth rate exceeding 20%. In 2019 alone, the global PVDF lithium battery binder market reached $300 million, and it is projected to reach $1.03 billion by 2026, with a compound annual growth rate (CAGR) of 25.21%.
The composition of a lithium-ion battery consists of five major components: the cathode, anode, electrolyte, separator, and casing.
PVDF is primarily used in the lithium battery industry as a binder, separator, and separator coating.
Lithium Battery Binder
To increase the electrode’s specific surface area and reduce resistance, the electrode’s active materials are typically in the form of powder, necessitating the use of a binder for adhesion.
Its primary function is to securely bond the active materials and conductive agents onto the current collector, preventing active material particles from detaching due to swelling during the battery’s charge and discharge processes, while also reducing impedance between the current collector and electrode material.
However, binders must endure long-term exposure to specific environments and must be capable of withstanding the effects of various conditions.
Currently, PVDF (Polyvinylidene Fluoride) is the primary choice for the cathode binder in the market.
Lithium Battery Separator
The lithium battery separator serves as an isolating barrier between the positive and negative electrodes of the battery.
And it can prevent direct contact between the active materials of the positive and negative electrodes and the occurrence of short circuits.
During electrochemical reactions, it maintains the necessary electrolyte and forms a pathway for ion movement.
Lithium Battery PVDF Separator / Lithium Battery PVDF Separator Microstructure
Lithium Battery Separator Coating
PVDF-coated separators for lithium batteries exhibit characteristics such as low internal resistance, high uniformity in terms of thickness and porosity, good mechanical properties, and excellent chemical and electrochemical stability.
PVDF, which stands for Polyvinylidene Fluoride, is a white crystalline polymer in powder form. It has a melting point of 170°C, a thermal decomposition temperature of over 316°C, and a long-term usage temperature range of -40 to 150°C. Moreover, it possesses exceptional resistance to chemical corrosion, high-temperature discoloration, oxidation, abrasion, flexibility, and a high impact strength.
Currently, PVDF-coated separators are categorized into water-based and oil-based types based on the solvent used. Due to the presence of nanofiber coatings, this new type of separator offers improved compatibility and adhesion to lithium battery electrodes compared to regular separators, significantly enhancing the battery’s high-temperature performance and safety.
Furthermore, this novel separator exhibits excellent absorbency for liquid electrolytes, with the ability to wick and retain liquids effectively.
It extends the battery’s cycle life, enhances its high-rate discharge performance, and boosts the battery’s output capacity by 20%. It is particularly suitable for high-end energy storage batteries and automotive power batteries.
Use of PVDF
The lithium battery market is in a period of rapid growth. Viewing from the application areas, power, energy storage, and the 3C industry are the primary drivers of development in the lithium-ion battery industry. The most significant applications include mobile phones, portable computers (laptops, tablets), compact cameras, wearable devices, portable lighting tools, power banks, energy storage equipment, and electric vehicles (passenger cars, utility vehicles, and specialized vehicles).
With the rapid development of new energy sources like secondary lithium batteries, the use of Polyvinylidene Fluoride (PVDF) resin in lithium batteries has also increased dramatically.
Driven by the growth in electric vehicle applications as part of sustainable transportation development, the demand for PVDF in lithium battery applications has reached double digits.
Asia is the largest market, and it may drive the increase in PVDF consumption.