Battery Glossary – Binder

We said that “binder” was inserted when manufacturing positive and negative electrodes in the mixing process. It is an additive that helps the active materials and conductive agents adhere to the current collector like an adhesive. Today, we will examine the binder.

What is Binder?

We introduced “slurry” as a material made in the electrode manufacturing process. In making slurries, properly mixing active materials, conductive agents, solvents, and additives is critical. Active materials and conductive agents need to be blended with current collectors thoroughly so that the mixture can be coated onto the current collector evenly, which can determine battery performance. What is added for the even spread of the slurry onto the current collector is the binder.

*Current collector: A component of thin electrodes in a rechargeable battery. It offers a channel for electrons to travel between in and outside the battery, prompting electrochemical reaction.

Types of Binders

Simply put, binders work as an adhesive. They are largely divided into non-water-based PVdF and water-based SBR and CMC binders. The SBR and CMC have higher binding strength than the PVdF, thereby requiring less amount of binder, and are more environmentally friendly because water is used as a solvent. Accordingly, researchers are focusing more on water-based binders.

Roles of Binders

Binders can have a significant impact on battery performance. In particular, a repeated charge-discharge cycle of a battery can result in a change in anode volume, undermining battery life and charging time. This can be resolved with the binder that enhances binding strength of electrode materials.

Binders are important both for the cathode and anode. Recently, the importance is growing even more as silicon is used as an anode material. The use of silicon can cause more volume expansion and the binder is expected to offset the problem. As such, even small amount of binder is playing an essential role. Indeed, the roles and importance of binder are worth remembering.