An essential component of an electric vehicle, lithium-ion battery! A key material that makes up a lithium-ion battery is the ‘anode binder.’ An anode binder plays an important role in mechanical stabilization of the anode active materials and heightening the battery efficiency. Today’s FOCUS ON looks into the anode binder, the key player that enhances the capacity and efficiency of a lithium-ion battery.

Anode Binder Serves as an Adhesive

Before we get onto the anode binder, let’s understand what a ‘Binder’ is. As the term tells you, a binder ‘binds,’ ‘ties,’ or ‘puts two things together.’ In Chemistry, binders serve the role of attaching ‘active materials (involved in the electrode reaction of an actual battery)’ and ‘conductive materials (facilitate the movement of electrons)’ to a thin layer known as the ‘collector.’ Here, collector is the part that lets electrons in and out of the active materials to facilitate electrochemical reactions when batteries are charged or discharged. When active and conductive materials are blended and attached to the collector uniformly, it stabilizes the battery capacity. To put it simply, a binder is an additive material that helps blend and apply the active and conductive materials evenly, plus maintain the mechanical properties like interfacial bonding and internal binding of the electrodes.

A binder is a non-conductive insulator, which varies by types depending on its application, such as in cathode or anode. The most common types are Line Contact PVdF (Poly-Vinyli-Dene Fluoride), Point Contact SBR (Styrene Butadiene Rubber), and Point Contact CMC (Carboxymethyl Cellulose). PVdF is a non-aqueous binder, whereas SBR and CMC are aqueous binders. Non-aqueous binders are not soluble in water and must be collected after disposal, generating environmental costs. However, aqueous binders use water as their solvent, reducing both environmental impacts and costs. What’s more, Point Contact binders SBR and CMC have better fixation than Line Contact binder PVdF. In most cases, non-aqueous PVdF is applied to the cathode, while aqueous SBR and CMC are applied to the anode. This is because cathode consists of materials whose volumes do not expand much, such as nickel, cobalt, and manganese, but anode is composed of materials with a larger variation of volumes.

Recently, an increasing number of cases use silicone as an anode material in place of graphite, which can expand the battery capacity by about ten times. Yet, silicone can swell up severely when the battery is charged or discharged, eventually shortening the battery lifespan. To solve this problem and complement the weaknesses of existing batteries, LG Chem has applied Carbon Nanotube (CNT) to their conductive materials, and also used a stronger binder.

When a binder has a poor bond, the electrodes expand during charging and discharging, creating a distance between the active materials. As a result, the number of electrons decreases, whereas they take more time to pass through.

To tackle this issue, LG Chem has optimized the composition and structure of the binder particles, and minimized the clumping between binders through a specially-designed functional monomer. Thanks to this change, there are more contact points with the active materials, improving the adhesion efficiency and bonding between the conductive and active materials. In addition, by preventing the binder from moving to the top of the electrode during its drying process, the binder could be evenly distributed within the electrode, enhancing its bonding with the active materials and collector. LG Chem’s anode binder boasts high electrochemical stability and excellent cycle when the battery is operated, whereas the battery’s internal resistance stays low. Furthermore, LG Chem is Korea’s largest producer of Carbon Nanotube (CNT) for the conductive materials that are applied to binders and silicone anode materials.

Anode binder’s application centered on batteries

LG Chem’s anode binders are applied to various batteries. It is found in the lithium-ion battery of an electric vehicle, or the ESS (Energy Storage System). ESS batteries are made both for homes and electrical grids. ESS battery for homes is connected to the solar panels to save energy at daytime and use that energy to provide electricity at nighttime. As for the ESS battery for grids, it is installed at wind or thermal power plants and substations, etc.

Today, we introduced the anode binder that enhances the capacity of a lithium-ion battery. With rising attention to electric vehicles and their power source, the lithium-ion battery, companies are investing much on R&D of technologies that heightens the capacity and efficiency of a battery. Keep your support for LG Chem, as the company continues to reinforce their strength in battery materials and produce a maximized-capacity of lithium-ion batteries.