In the lithium battery industry, the most talked about topics are high nickel, silicon carbon, large cylindrical, and solid-state batteries.

But few people are willing to calm down and chat about the tuft of glue that "twists" these high-end materials together.

Adhesives and dispersants often hide in the corners of the formula table: the amount used is not large, but it determines whether the polarizer can be applied stably, pressed tightly, filled quickly, and used for a long time.

Today, we would like to turn our attention back to this "overlooked key corner" - hydrogenated nitrile butadiene (HNBR), as well as its present and future in the field of lithium batteries. We would also like to take this opportunity to formally introduce ourselves, Chambroad Sinopoly, who are firmly rooted in this track.

1、 Who is hydrogenated nitrile? From 'sealing ring player' to 'new energy darling'

Hydrogenated nitrile rubber (HNBR) is essentially a highly saturated specialty elastomer obtained by selective hydrogenation of ordinary nitrile rubber (NBR): the main chain double bond is hydrogenated while the polar nitrile group is retained.

It is precisely this structure that gives it two major characteristics:

·Very 'resistant to manufacturing': resistant to oil, heat, chemical corrosion, ozone, aging, and can work stably at -40~160 ℃, with high strength, wear resistance, and minimal permanent compression deformation;

·Very versatile: especially suitable for scenarios involving contact with fuel oil, lubricants, refrigerants, acidic and alkaline media, it has been widely used in high demand applications such as automotive engine compartments, oil and gas drilling and production pipelines, and industrial seals for a long time.

In traditional rubber rings, HNBR is often referred to as the "crown jewel of rubber" - not because it is "expensive", but because of its comprehensive performance under extreme working conditions, which is difficult to be completely replaced by other single rubbers.

It is precisely this "anti manufacturing+reliable" temperament that has quietly crossed over and entered the seemingly ordinary slurry behind lithium-ion batteries.

2、 From sealing ring to pole piece: Why did HNBR enter lithium battery factories?

To understand why HNBR suddenly became popular in the lithium-ion battery industry, we need to first return to a fundamental question: what exactly are binders/dispersants doing?

A polarizer is roughly made by coating, drying, and rolling a slurry composed of active substance (positive and negative electrode powder), conductive agent, binder/dispersant, and solvent. The task of adhesive can be summarized into four words: "stick well, support" - it not only needs to firmly adhere to particles, but also support the entire "skeleton" in charge and discharge expansion and contraction, thermal shock, mechanical stress, and cannot increase too much resistance or be easily "corroded" by electrolyte.

In many traditional formulas, PVDF is used as the main binder for the positive electrode, while water-based systems such as SBR/CMC are used as the main binder for the negative electrode. With the increasingly stringent demands for high nickel, high voltage, fast charging, high rate, and long lifespan, traditional systems are gradually exposing some pain points:

·High temperature storage is prone to powder loss and cracking

·Thick coated polarizer has high internal resistance and polarization

·CNT and other conductive agents are difficult to disperse, and the coating window is narrow

·The process window is small, and even a slight deviation can lead to rework

This is exactly where HNBR leverages its strengths.